The atypical hydrodynamics of the Mayotte Lagoon (Indian Ocean): Effects on water age and potential impact on plankton productivity

NASA Astrophysics Data System (ADS)

Chevalier, C.; Devenon, J. L.; Pagano, M.; Rougier, G.; Blanchot, J.; Arfi, R.

2017-09-01

In mesotidal lagoons of the Indian Ocean, the coral reef barrier may be temporarily submerged at high tide and partially exposed at low tide, and this may cause unusual lagoon dynamics. A field measurement campaign was conducted in the north-east Mayotte Lagoon in order to understand these processes. An experimental approach was used, combining measurements taken by 1) a side-mounted Acoustic Doppler Current Profiler (ADCP) on a moving boat along transects through the reef passages (17 transects) and 2) by more conventional high-resolution moored ADCP measurements. A specific tidal analysis methodology was used to determine the spatial variability of the velocity. The tidal hydrodynamics within the lagoon were determined using a numerical model and then analyzed. The tide acted as a quasi-progressive forced wave in the lagoon: at low tide, water entered through the south passage, over the reef and left the lagoon through the north passage. This flow was reversed at high tide. The tide-driven quasi-progressive wave created a specific lagoon dynamics. Contrary to most other channel lagoons, the flow over the reef was mainly outward. This increases the inflow through the passages, which renews the water in the lagoon as shown by the indicators of age and origin of the water inside the lagoon. This study also showed the importance of these indicators for better understanding the variations and levels of plankton biomass (with chlorophyll concentration as proxy) which is quite high in this lagoon.

Marshall Islands Fringing Reef and Atoll Lagoon Observations of the Tohoku Tsunami

NASA Astrophysics Data System (ADS)

Ford, Murray; Becker, Janet M.; Merrifield, Mark A.; Song, Y. Tony

2014-12-01

The magnitude 9.0 Tohoku earthquake on 11 March 2011 generated a tsunami which caused significant impacts throughout the Pacific Ocean. A description of the tsunami within the lagoons and on the surrounding fringing reefs of two mid-ocean atoll islands is presented using bottom pressure observations from the Majuro and Kwajalein atolls in the Marshall Islands, supplemented by tide gauge data in the lagoons and by numerical model simulations in the deep ocean. Although the initial wave arrival was not captured by the pressure sensors, subsequent oscillations on the reef face resemble the deep ocean tsunami signal simulated by two numerical models, suggesting that the tsunami amplitudes over the atoll outer reefs are similar to that in deep water. In contrast, tsunami oscillations in the lagoon are more energetic and long lasting than observed on the reefs or modelled in the deep ocean. The tsunami energy in the Majuro lagoon exhibits persistent peaks in the 30 and 60 min period bands that suggest the excitation of closed and open basin normal modes, while energy in the Kwajalein lagoon spans a broader range of frequencies with weaker, multiple peaks than observed at Majuro, which may be associated with the tsunami behavior within the more irregular geometry of the Kwajalein lagoon. The propagation of the tsunami across the reef flats is shown to be tidally dependent, with amplitudes increasing/decreasing shoreward at high/low tide. The impact of the tsunami on the Marshall Islands was reduced due to the coincidence of peak wave amplitudes with low tide; however, the observed wave amplitudes, particularly in the atoll lagoon, would have led to inundation at different tidal phases.

Nitrogen enrichment and speciation in a coral reef lagoon driven by groundwater inputs of bird guano

NASA Astrophysics Data System (ADS)

McMahon, Ashly; Santos, Isaac R.

2017-09-01

While the influence of river inputs on coral reef biogeochemistry has been investigated, there is limited information on nutrient fluxes related to submarine groundwater discharge (SGD). Here, we investigate whether significant saline groundwater-derived nutrient inputs from bird guano drive coral reef photosynthesis and calcification off Heron Island (Great Barrier Reef, Australia). We used multiple experimental approaches including groundwater sampling, beach face transects, and detailed time series observations to assess the dynamics and speciation of groundwater nutrients as they travel across the island and discharge into the coral reef lagoon. Nitrogen speciation shifted from nitrate-dominated groundwater (>90% of total dissolved nitrogen) to a coral reef lagoon dominated by dissolved organic nitrogen (DON; ˜86%). There was a minimum input of nitrate of 2.1 mmol m-2 d-1 into the lagoon from tidally driven submarine groundwater discharge estimated from a radon mass balance model. An independent approach based on the enrichment of dissolved nutrients during isolation at low tide implied nitrate fluxes of 5.4 mmol m-2 d-1. A correlation was observed between nitrate and daytime net ecosystem production and calcification. We suggest that groundwater nutrients derived from bird guano may offer a significant addition to oligotrophic coral reef lagoons and fuel ecosystem productivity and the coastal carbon cycle near Heron Island. The large input of groundwater nutrients in Heron Island may serve as a natural ecological analogue to other coral reefs subject to large nutrient inputs from anthropogenic sources.

Groundwater and porewater as a major source of alkalinity to a fringing coral reef lagoon (Muri Lagoon, Cook Islands)

NASA Astrophysics Data System (ADS)

Cyronak, T.; Santos, I. R.; Erler, D. V.; Eyre, B. D.

2012-11-01

To better predict how ocean acidification will affect coral reefs, it is important to understand how biogeochemical cycles on reefs alter carbonate chemistry over various temporal and spatial scales. This study quantifies the contribution of fresh groundwater discharge (as traced by radon) and shallow porewater exchange (as quantified from advective chamber incubations) to total alkalinity (TA) dynamics on a fringing coral reef lagoon along the southern Pacific island of Rarotonga over a tidal and diel cycle. Benthic alkalinity fluxes were affected by the advective circulation of water through permeable sediments, with net daily flux rates of carbonate alkalinity ranging from -1.55 to 7.76 mmol m-2 d-1, depending on the advection rate. Submarine groundwater discharge (SGD) was a source of TA to the lagoon, with the highest flux rates measured at low tide, and an average daily TA flux of 1080 mmol m-2 d-1. Both sources of TA were important on a reef wide basis, although SGD acted solely as a delivery mechanism of TA to the lagoon, while porewater advection was either a sink or source of TA dependant on the time of day. On a daily basis, groundwater can contribute approximately 70% to 80% of the TA taken up by corals within the lagoon. This study describes overlooked sources of TA to coral reef ecosystems that can potentially alter water-column carbonate chemistry. We suggest that porewater and groundwater fluxes of TA should be taken into account in ocean acidification models in order to properly address changing carbonate chemistry within coral reef ecosystems.

Hydrodynamic response of a fringing coral reef to a rise in mean sea level

NASA Astrophysics Data System (ADS)

Taebi, Soheila; Pattiaratchi, Charitha

2014-07-01

Ningaloo Reef, located along the northwest coast of Australia, is one of the longest fringing coral reefs in the world extending ~300 km. Similar to other fringing reefs, it consists of a barrier reef ~1-6 km offshore with occasional gaps, backed by a shallow lagoon. Wave breaking on the reef generates radiation stress gradients that produces wave setup across the reef and lagoon and mean currents across the reef. A section of Ningaloo Reef at Sandy Bay was chosen as the focus of an intense 6-week field experiment and numerical simulation using the wave model SWAN coupled to the three-dimensional circulation model ROMS. The physics of nearshore processes such as wave breaking, wave setup and mean flow across the reef was investigated in detail by examining the various momentum balances established in the system. The magnitude of the terms and the distance of their peaks from reef edge in the momentum balance were sensitive to the changes in mean sea level, e.g. the wave forces decreased as the mean water depth increased (and hence, wave breaking dissipation was reduced). This led to an increase in the wave power at the shoreline, a slight shift of the surf zone to the lee side of the reef and changes in the intensity of the circulation. The predicted hydrodynamic fields were input into a Lagrangian particle tracking model to estimate the transport time scale of the reef-lagoon system. Flushing time of the lagoon with the open ocean was computed using two definitions in renewal of semi-enclosed water basins and revealed the sensitivity of such a transport time scale to methods. An increase in the lagoon exchange rate at smaller mean sea-level rise and the decrease at higher mean sea-level rise was predicted through flushing time computed using both methods.

Impact of warming events on reef-scale temperature variability as captured in two Little Cayman coral Sr/Ca records

NASA Astrophysics Data System (ADS)

von Reumont, J.; Hetzinger, S.; Garbe-Schönberg, D.; Manfrino, C.; Dullo, W.-Chr.

2016-03-01

The rising temperature of the world's oceans is affecting coral reef ecosystems by increasing the frequency and severity of bleaching and mortality events. The susceptibility of corals to temperature stress varies on local and regional scales. Insights into potential controlling parameters are hampered by a lack of long term in situ data in most coral reef environments and sea surface temperature (SST) products often do not resolve reef-scale variations. Here we use 42 years (1970-2012) of coral Sr/Ca data to reconstruct seasonal- to decadal-scale SST variations in two adjacent but distinct reef environments at Little Cayman, Cayman Islands. Our results indicate that two massive Diploria strigosa corals growing in the lagoon and in the fore reef responded differently to past warming events. Coral Sr/Ca data from the shallow lagoon successfully record high summer temperatures confirmed by in situ observations (>33°C). Surprisingly, coral Sr/Ca from the deeper fore reef is strongly affected by thermal stress events, although seasonal temperature extremes and mean SSTs at this site are reduced compared to the lagoon. The shallow lagoon coral showed decadal variations in Sr/Ca, supposedly related to the modulation of lagoonal temperature through varying tidal water exchange, influenced by the 18.6 year lunar nodal cycle. Our results show that reef-scale SST variability can be much larger than suggested by satellite SST measurements. Thus, using coral SST proxy records from different reef zones combined with in situ observations will improve conservation programs that are developed to monitor and predict potential thermal stress on coral reefs.

Mechanisms of sediment transport to shoreline salients onshore of fringing coral reefs

NASA Astrophysics Data System (ADS)

Hansen, J.; Cuttler, M.; Traykovski, P.; Lowe, R.; Buckley, M. L.; Storlazzi, C. D.; Rosenberger, K. J.

2016-12-01

Shoreline salients, often extending several hundred metres seaward relative to the adjacent shoreline, are a common morphological feature found in the lee of many fringing coral reefs globally. However, the physical mechanisms that govern the formation and equilibrium dynamics of these salients remains poorly understood. A recent field experiment in NW Australia at Ningaloo Reef examined the mechanism of sediment delivery to a salient that extends 700 m seaward onshore of a 4 km long fringing reef that sits 2 km offshore. The experimental array consisted of wave, water level, and velocity measurements at >20 sites from 20 m depth offshore of the reef, the reef crest, and numerous sites throughout the 3 m depth lagoon shoreward of the reef. Two sites within the lagoon, one each side of the salient, also measured the migration of 0.5 m wavelength, 0.1 m high sand ripples using horizontal and vertically mounted echo sounders. Consistent with existing theory, mean (wave-averaged) flows in the lagoon shoreward of the reef and along the shoreline were divergent up to 0.2 m/s, corresponding to the circulation pattern resulting from wave breaking induced setup on the reef and associated mass flux into the lagoon, and seaward return flow through two lateral channels. These divergent alongshore mean flows are inconsistent the accreted shoreline morphology. However, the two sites that measured ripple properties and migration showed consistent migration in the local (salient following) onshore direction up to 2 m/day (mean 0.14 m/day across the two sites) resulting in onshore sediment fluxes as large as 200 kg/m/day (mean 10.1 kg/m/day) assuming ripple migration equates to net bedload transport. Despite the considerable infragravity energy within the lagoon ( 50% of the energy spectrum) the 0.5 m wavelength ripples were suborbital based on the orbital diameter of the 0.2-0.5 m high short waves which enter the lagoon via refraction through the lateral channels and incomplete dissipation over the reef. These preliminary results indicate that onshore ripple migration of biogenic sediment generated by the coral reef from short waves within the lagoon is the primary source of sediment to the salient. Additional analyses will focus on the hydrodynamic mechanisms responsible for the variable rate of migration.

Groundwater and porewater as major sources of alkalinity to a fringing coral reef lagoon (Muri Lagoon, Cook Islands)

NASA Astrophysics Data System (ADS)

Cyronak, T.; Santos, I. R.; Erler, D. V.; Eyre, B. D.

2013-04-01

To better predict how ocean acidification will affect coral reefs, it is important to understand how biogeochemical cycles on reefs alter carbonate chemistry over various temporal and spatial scales. This study quantifies the contribution of shallow porewater exchange (as quantified from advective chamber incubations) and fresh groundwater discharge (as traced by 222Rn) to total alkalinity (TA) dynamics on a fringing coral reef lagoon along the southern Pacific island of Rarotonga over a tidal and diel cycle. Benthic alkalinity fluxes were affected by the advective circulation of water through permeable sediments, with net daily flux rates of carbonate alkalinity ranging from -1.55 to 7.76 mmol m-2 d-1, depending on the advection rate. Submarine groundwater discharge (SGD) was a source of TA to the lagoon, with the highest flux rates measured at low tide, and an average daily TA flux of 1080 mmol m-2 d-1 at the sampling site. Both sources of TA were important on a reef-wide basis, although SGD acted solely as a delivery mechanism of TA to the lagoon, while porewater advection was either a sink or source of TA dependent on the time of day. This study describes overlooked sources of TA to coral reef ecosystems that can potentially alter water column carbonate chemistry. We suggest that porewater and groundwater fluxes of TA should be taken into account in ocean acidification models in order to properly address changing carbonate chemistry within coral reef ecosystems.

Nitrous oxide and methane dynamics in a coral reef lagoon driven by pore water exchange: Insights from automated high-frequency observations

NASA Astrophysics Data System (ADS)

O'Reilly, Chiara; Santos, Isaac R.; Cyronak, Tyler; McMahon, Ashly; Maher, Damien T.

2015-04-01

Automated cavity ring down spectroscopy was used to make continuous measurements of dissolved methane, nitrous oxide, and carbon dioxide in a coral reef lagoon for 2 weeks (Heron Island, Great Barrier Reef). Radon (222Rn) was used to trace the influence of tidally driven pore water exchange on greenhouse gas dynamics. Clear tidal variation was observed for CH4, which correlated to 222Rn in lagoon waters. N2O correlated to 222Rn during the day only, which appears to be a response to coupled nitrification-denitrification in oxic sediments, fueled by nitrate derived from bird guano. The lagoon was a net source of CH4 and N2O to the atmosphere and a sink for atmospheric CO2. The estimated pore water-derived CH4 and N2O fluxes were 3.2-fold and 24.0-fold greater than the fluxes to the atmosphere. Overall, pore water and/or groundwater exchange were the only important sources of CH4 and major controls of N2O in the coral reef lagoon.

Coral mucus functions as an energy carrier and particle trap in the reef ecosystem.

PubMed

Wild, Christian; Huettel, Markus; Klueter, Anke; Kremb, Stephan G; Rasheed, Mohammed Y M; Jørgensen, Bo B

2004-03-04

Zooxanthellae, endosymbiotic algae of reef-building corals, substantially contribute to the high gross primary production of coral reefs, but corals exude up to half of the carbon assimilated by their zooxanthellae as mucus. Here we show that released coral mucus efficiently traps organic matter from the water column and rapidly carries energy and nutrients to the reef lagoon sediment, which acts as a biocatalytic mineralizing filter. In the Great Barrier Reef, the dominant genus of hard corals, Acropora, exudes up to 4.8 litres of mucus per square metre of reef area per day. Between 56% and 80% of this mucus dissolves in the reef water, which is filtered through the lagoon sands. Here, coral mucus is degraded at a turnover rate of at least 7% per hour. Detached undissolved mucus traps suspended particles, increasing its initial organic carbon and nitrogen content by three orders of magnitude within 2 h. Tidal currents concentrate these mucus aggregates into the lagoon, where they rapidly settle. Coral mucus provides light energy harvested by the zooxanthellae and trapped particles to the heterotrophic reef community, thereby establishing a recycling loop that supports benthic life, while reducing loss of energy and nutrients from the reef ecosystem.

Self-generated morphology in lagoon reefs

PubMed Central

Hamblin, Michael G.

2015-01-01

The three-dimensional form of a coral reef develops through interactions and feedbacks between its constituent organisms and their environment. Reef morphology therefore contains a potential wealth of ecological information, accessible if the relationships between morphology and ecology can be decoded. Traditionally, reef morphology has been attributed to external controls such as substrate topography or hydrodynamic influences. Little is known about inherent reef morphology in the absence of external control. Here we use reef growth simulations, based on observations in the cellular reefs of Western Australia’s Houtman Abrolhos Islands, to show that reef morphology is fundamentally determined by the mechanical behaviour of the reef-building organisms themselves—specifically their tendency to either remain in place or to collapse. Reef-building organisms that tend to remain in place, such as massive and encrusting corals or coralline algae, produce nodular reefs, whereas those that tend to collapse, such as branching Acropora, produce cellular reefs. The purest reef growth forms arise in sheltered lagoons dominated by a single type of reef builder, as in the branching Acropora-dominated lagoons of the Abrolhos. In these situations reef morphology can be considered a phenotype of the predominant reef building organism. The capacity to infer coral type from reef morphology can potentially be used to identify and map specific coral habitat in remotely sensed images. More generally, identifying ecological mechanisms underlying other examples of self-generated reef morphology can potentially improve our understanding of present-day reef ecology, because any ecological process capable of shaping a reef will almost invariably be an important process in real time on the living reef. PMID:26175962

Drivers of pCO2 dynamics in two contrasting coral reef lagoons: The influence of submarine groundwater discharge (Invited)

NASA Astrophysics Data System (ADS)

Cyronak, T.; Santos, I. R.; Erler, D.; Maher, D. T.; Eyre, B.

2013-12-01

The carbon chemistry of coral reef lagoons can be highly variable over short time scales. While much of the diel variability in seawater carbon chemistry is explained by biological processes, external sources such as river and groundwater seepage may deliver large amounts of organic and inorganic carbon to coral reefs and represent a poorly understood feedback to ocean acidification. Here, we assess the impact of submarine groundwater discharge (SGD) on pCO2 variability in two coral reef lagoons with distinct SGD driving mechanisms. Diel variability of pCO2 in the two ecosystems was explained by a combination of biological drivers and SGD inputs. In Rarotonga, a South Pacific volcanic island, SGD was driven primarily by a steep terrestrial hydraulic gradient, and the lagoon was influenced by the high pCO2 (5,501 μatm) of the fresh groundwater. In Heron Island, a Great Barrier Reef coral cay, SGD was dominated by seawater recirculation through sediments (i.e. tidal pumping) and pCO2 was mainly impacted through the stimulation of biological processes. The Rarotonga water column had a relatively higher average pCO2 (549 μatm) than Heron Island (471 μatm). However, pCO2 exhibited a greater diel range in Heron Island (778 μatm) than in Rarotonga (507 μatm). The Rarotonga lagoon received 31.2 mmol CO2 m-2 d-1 from SGD, while the Heron Island lagoon received 12.3 mmol CO2 m-2 d-1. Over the course of this study both systems were sources of CO2 to the atmosphere (3.00 to 9.67 mmol CO2 m-2 d-1), with SGD-derived CO2 contributing a large portion to the air-sea CO2 flux. The relationship between both water column pH and aragonite saturation state (ΩAr) and radon (222Rn) concentrations indicate that SGD may enhance the local acidification of some coral reef lagoons. Studies measuring the carbon chemistry of coral reefs (e.g. community metabolism, calcification rates) may need to consider SGD-derived CO2.

Geomorphology and sediment transport on a submerged back-reef sand apron: One Tree Reef, Great Barrier Reef

NASA Astrophysics Data System (ADS)

Harris, Daniel L.; Vila-Concejo, Ana; Webster, Jody M.

2014-10-01

Back-reef sand aprons are conspicuous and dynamic sedimentary features in coral reef systems. The development of these features influences the evolution and defines the maturity of coral reefs. However, the hydrodynamic processes that drive changes on sand aprons are poorly understood with only a few studies directly assessing sediment entrainment and transport. Current and wave conditions on a back-reef sand apron were measured during this study and a digital elevation model was developed through topographic and bathymetric surveying of the sand apron, reef flats and lagoon. The current and wave processes that may entrain and transport sediment were assessed using second order small amplitude (Stokes) wave theory and Shields equations. The morphodynamic interactions between current flow and geomorphology were also examined. The results showed that sediment transport occurs under modal hydrodynamic conditions with waves the main force entraining sediment rather than average currents. A morphodynamic relationship between current flow and geomorphology was also observed with current flow primarily towards the lagoon in shallow areas of the sand apron and deeper channel-like areas directing current off the sand apron towards the lagoon or the reef crest. These results show that the short-term mutual interaction of hydrodynamics and geomorphology in coral reefs can result in morphodynamic equilibrium.

Influence of submarine springs and wastewater on nutrient dynamics of Caribbean seagrass meadows

NASA Astrophysics Data System (ADS)

Carruthers, T. J. B.; van Tussenbroek, B. I.; Dennison, W. C.

2005-08-01

The east coast of the Yucatan Peninsula, Mexico, consists of highly permeable limestone, such that surface flow and rivers are absent in this region. Extensive underground cave systems connect sink holes (cenotes) to submarine springs (ojos de aqua), which vent into the seagrass meadows of the adjacent oligotrophic coastal lagoons. This study investigated the potential for these submarine springs to influence nutrient processes within seagrass meadows, by assessing nutrient status of Thalassia testudinum meadows in two contrasting coastal lagoons along the north eastern Yucatan peninsula. Tissue nutrient concentrations as well as δ 15N values of T. testudinum were surveyed in the Puerto Morelos Reef Lagoon and the Nichupte Lagoon System, Cancun Hotel Zone, during an extended dry period and again following heavy rainfall. After a period of heavy rainfall, T. testudinum near submarine springs in Puerto Morelos Reef Lagoon had exceptionally high leaf tissue phosphorus concentrations of 0.38±0.06%. These submarine springs may have been a direct source of phosphorus and/or a source of iron to this very iron limited carbonate system. Thalassia testudinum nutrient concentrations suggest that nitrogen loading to the Nichupte Lagoon System is regionally high and has increased over the past decade (mean leaf N: 2.04% N in 1991 to 2.71% N in 2002). Nitrogen content in leaf tissue of T. testudinum was significantly higher within the poorly flushed Nichupte Lagoon System (2.93±0.12% N) than in the well-flushed Puerto Morelos Reef Lagoon (1.80±0.07% N). Stable isotope ratios of nitrogen suggest that this high and increasing nitrogen loading within the Nichupte Lagoon System is a result of wastewater nitrogen (δ 15N 9.06±0.07 in northern Nichupte Lagoon System vs. 1.69±0.07 in Puerto Morelos Reef Lagoon).

Multi-site evaluation of IKONOS data for classification of tropical coral reef environments

USGS Publications Warehouse

Andrefouet, S.; Kramer, Philip; Torres-Pulliza, D.; Joyce, K.E.; Hochberg, E.J.; Garza-Perez, R.; Mumby, P.J.; Riegl, Bernhard; Yamano, H.; White, W.H.; Zubia, M.; Brock, J.C.; Phinn, S.R.; Naseer, A.; Hatcher, B.G.; Muller-Karger, F. E.

2003-01-01

Ten IKONOS images of different coral reef sites distributed around the world were processed to assess the potential of 4-m resolution multispectral data for coral reef habitat mapping. Complexity of reef environments, established by field observation, ranged from 3 to 15 classes of benthic habitats containing various combinations of sediments, carbonate pavement, seagrass, algae, and corals in different geomorphologic zones (forereef, lagoon, patch reef, reef flats). Processing included corrections for sea surface roughness and bathymetry, unsupervised or supervised classification, and accuracy assessment based on ground-truth data. IKONOS classification results were compared with classified Landsat 7 imagery for simple to moderate complexity of reef habitats (5-11 classes). For both sensors, overall accuracies of the classifications show a general linear trend of decreasing accuracy with increasing habitat complexity. The IKONOS sensor performed better, with a 15-20% improvement in accuracy compared to Landsat. For IKONOS, overall accuracy was 77% for 4-5 classes, 71% for 7-8 classes, 65% in 9-11 classes, and 53% for more than 13 classes. The Landsat classification accuracy was systematically lower, with an average of 56% for 5-10 classes. Within this general trend, inter-site comparisons and specificities demonstrate the benefits of different approaches. Pre-segmentation of the different geomorphologic zones and depth correction provided different advantages in different environments. Our results help guide scientists and managers in applying IKONOS-class data for coral reef mapping applications. ?? 2003 Elsevier Inc. All rights reserved.

Are Sea Surface Temperature satellite measurements reliable proxies of lagoon temperature in the South Pacific?

NASA Astrophysics Data System (ADS)

Van Wynsberge, Simon; Menkes, Christophe; Le Gendre, Romain; Passfield, Teuru; Andréfouët, Serge

2017-12-01

In remote coral reef environments, lagoon and reef in situ measurements of temperature are scarce. Sea Surface Temperature (SST) measured by satellite has been frequently used as a proxy of the lagoon temperature experienced by coral reef organisms (TL) especially during coral bleaching events. However, the link between SST and TL is poorly characterized. First, we compared the correlation between various SST series and TL from 2012 to 2016 in three atolls and one island in the Central South Pacific Ocean. Simple linear correlation between SST and TL ranged between 0.44 and 0.97 depending on lagoons, localities of sensors, and type of SST data. High-resolution-satellite-measurements of SST inside the lagoons did not outperform oceanic SST series, suggesting that SST products are not adapted for small lagoons. Second, we modelled the difference between oceanic SST and TL as a function of the drivers of lagoon water renewal and mixing, namely waves, tide, wind, and season. The multivariate models reduced significantly the bias between oceanic SST and TL. In atoll lagoons, and probably in other hydrodynamically semi-open systems, a correction taking into account these factors is necessary when SST are used to characterize organisms' thermal stress thresholds.

Bikini scientific resurvey. Volume II. Report of the technical director. Technical report

DOE Office of Scientific and Technical Information (OSTI.GOV)

Not Available

1947-12-01

Contents: Island and Reef Geology; Submarine Geology; Drilling Operations; Radiobiology Studies; Reef and Lagoon Fishes; Pelagic Fishes; Taxonomy and Teratology of Fishes; Invertebrate Embryology; Vertebrate Embryology; Reef and Lagoon Algae; Chemical Effects of Organisms Upon Sea Water; The Insect Population; Marine Invertebrates; Land Animals; Plankton Studies; Counter-Room Activities; Radiochemical Analyses; Soils Chemistry; Low-Level Radiation Studies; Army Engineering Studies; Aerological Data; Bacteriological Investigations; Radiological Safety; Radiological Health; Technical Director's Summary.

The structure and productivity of the Thalassia testudinum community in Bon Accord Lagoon, Tobago.

PubMed

Juman, Rahanna A

2005-05-01

The Thalassia testudinum dominated seagrass community in the Buccoo Reef/ Bon Accord Lagoon Marine Park, measures 0.5 km(2) and is part of a contiguous coral reef, seagrass bed and mangrove swamp system in southwest Tobago. 7 testudinum coverage, productivity and percent turnover rates were measured from February 1998 to February 1999 at four sample locations, while total T. testudinum biomass was measured at two locations in the lagoon from 1992-2002. Productivity and turnover rates varied spatially and seasonally. They were higher in the back-reef area than in the mangrove-fringed lagoon, and were lowest at locations near to a sewage outfall. 7 testudinum coverage ranged from 6.6% in the lagoon to 68.5% in the back-reef area while productivity ranged from 3.9 to 4.9 g dry wt m(-2) d(-1) . Productivity and percentage turnover rates were higher in the dry season (January-June) than in the wet season (July-December). Productivity ranged from 3.0 in the wet season to 5.0 g dry wt m2 d-' in the dry season while percentage turnover rates ranged from 4.2% to 5.6%. Total Thalassia biomass and productivity in Bon Accord Lagoon were compared to six similar sites in the Caribbean that also participate in the Caribbean Coastal Marine Productivity Program (CARICOMP). This seagrass community is being negatively impacted by nutrient-enriched conditions.

Acropora interbranch skeleton Sr/Ca ratios: Evaluation of a potential new high-resolution paleothermometer

NASA Astrophysics Data System (ADS)

Sadler, James; Nguyen, Ai D.; Leonard, Nicole D.; Webb, Gregory E.; Nothdurft, Luke D.

2016-04-01

The majority of coral geochemistry-based paleoclimate reconstructions in the Indo-Pacific are conducted on selectively cored colonies of massive Porites. This restriction to a single genus may make it difficult to amass the required paleoclimate data for studies that require deep reef coring techniques. Acropora, however, is a highly abundant coral genus in both modern and fossil reef systems and displays potential as a novel climate archive. Here we present a calibration study for Sr/Ca ratios recovered from interbranch skeleton in corymbose Acropora colonies from Heron Reef, southern Great Barrier Reef. Significant intercolony differences in absolute Sr/Ca ratios were normalized by producing anomaly plots of both coral geochemistry and instrumental water temperature records. Weighted linear regression of these anomalies from the lagoon and fore-reef slope provide a sensitivity of -0.05 mmol/mol °C-1, with a correlation coefficient (r2 = 0.65) comparable to those of genera currently used in paleoclimate reconstructions. Reconstructions of lagoon and reef slope mean seasonality in water temperature accurately identify the greater seasonal amplitude observed in the lagoon of Heron Reef. A longer calibration period is, however, required for reliable reconstructions of annual mean water temperatures.

Sponge distribution across Davies Reef, Great Barrier Reef, relative to location, depth, and water movement

NASA Astrophysics Data System (ADS)

Wilkinson, Clive R.; Evans, Elizabeth

1989-06-01

Sponge populations were surveyed at different depths in three zones of Davies Reef, a large platform reef of the central Great Barrier Reef. Depth is the major discriminatory factor as few sponges are found within the first 10 m depth and maximal populations occur between 15 m and 30 m on fore-reef, lagoon and back-reef slopes. Reef location is another major factor, with the lagoon containing a significantly different sponge population to either the fore-reef or the back-reef slopes. Physical factors are considered to be the major influences behind these patterns. Physical turbulence is strongest within the first 10 m and apparently limits sponge growth within these shallow zones. Insufficient photosynthetic radiation limits the growth of the sponge population below 30 m depth as many of the species are phototrophic with a dependence on cyanobacterial symbionts for nutrition. Sponge populations on the outer (fore- and back-) reef slopes are comparable with each other but different from those on lagoon slopes where currents are reduced and fine sediment loads are higher. The largest populations occur on the back-reef slope where currents are stronger and there are possibly higher concentrations of organic nutrients originating from the more productive shallow parts of the reef. While there are correlations between sponge populations and environmental parameters, data are insufficient to enable more definitive conclusions to be drawn. Most sponge species are distributed widely over the reef, however, some are restricted to a few habitats and, hence, may be used to characterize those habitats.

Diazotrophic bacterioplankton in a coral reef lagoon: phylogeny, diel nitrogenase expression and response to phosphate enrichment.

PubMed

Hewson, Ian; Moisander, Pia H; Morrison, Amanda E; Zehr, Jonathan P

2007-05-01

We investigated diazotrophic bacterioplankton assemblage composition in the Heron Reef lagoon (Great Barrier Reef, Australia) using culture-independent techniques targeting the nifH fragment of the nitrogenase gene. Seawater was collected at 3 h intervals over a period of 72 h (i.e. over diel as well as tidal cycles). An incubation experiment was also conducted to assess the impact of phosphate (PO(4)3*) availability on nifH expression patterns. DNA-based nifH libraries contained primarily sequences that were most similar to nifH from sediment, microbial mat and surface-associated microorganisms, with a few sequences that clustered with typical open ocean phylotypes. In contrast to genomic DNA sequences, libraries prepared from gene transcripts (mRNA amplified by reverse transcription-polymerase chain reaction) were entirely cyanobacterial and contained phylotypes similar to those observed in open ocean plankton. The abundance of Trichodesmium and two uncultured cyanobacterial phylotypes from previous studies (group A and group B) were studied by quantitative-polymerase chain reaction in the lagoon samples. These were detected as transcripts, but were not detected in genomic DNA. The gene transcript abundance of these phylotypes demonstrated variability over several diel cycles. The PO(4)3* enrichment experiment had a clearer pattern of gene expression over diel cycles than the lagoon sampling, however PO(4)3* additions did not result in enhanced transcript abundance relative to control incubations. The results suggest that a number of diazotrophs in bacterioplankton of the reef lagoon may originate from sediment, coral or beachrock surfaces, sloughing into plankton with the flooding tide. The presence of typical open ocean phylotype transcripts in lagoon bacterioplankton may indicate that they are an important component of the N cycle of the coral reef.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Mazzullo, S.J.; Anderson-Underwood, K.E.; Burke, C.D.

Coral patch reefs are major components of Holocene platform carbonate facies systems in tropical and subtropical areas. The biotic composition, growth and relationship to sea level history, and diagenetic attributes of a representative Holocene patch reef ([open quotes]Elmer Reef[close quotes]) in the Mexico Rocks complex in northern Belize are described and compared to those of Holocene patch reefs in southern Belize. Elmer Reef has accumulated in shallow (2.5 m) water over the last 420 yr, under static sea level conditions. Rate of vertical construction is 0.3-0.5 m/100 yr, comparable to that of patch reefs in southern Belize. A pronounced coralmore » zonation exists across Elmer Reef, with Monastrea annularis dominating on its crest and Acropora cervicornis occurring on its windward and leeward flanks. The dominance of Montastrea on Elmer Reef is unlike that of patch reefs in southern Belize, in which this coral assumes only a subordinate role in reef growth relative to that of Acropora palmata. Elmer Reef locally is extensively biodegraded and marine, fibrous aragonite and some bladed high-magnesium calcite cements occur throughout the reef section, partially occluding corallites and interparticle pores in associated sands. Patch reefs in southern Belize have developed as catch-up and keep-up reefs in a transgressive setting. In contrast, the dominant mode of growth of Elmer Reef, and perhaps other patch reefs in Mexico Rocks, appears to be one of lateral rather than vertical accretion. This style of growth occurs in a static sea level setting where there is only limited accommodation space because of the shallowness of the water, and such reefs are referred to as [open quotes]expansion reefs[close quotes]. 39 refs., 8 figs., 2 tabs.« less

Regional hard coral distribution within geomorphic and reef flat ecological zones determined by satellite imagery of the Xisha Islands, South China Sea

NASA Astrophysics Data System (ADS)

Zuo, Xiuling; Su, Fenzhen; Zhao, Huanting; Zhang, Junjue; Wang, Qi; Wu, Di

2017-05-01

Coral reefs in the Xisha Islands (also known as the Paracel Islands in English), South China Sea, have experienced dramatic declines in coral cover. However, the current regional scale hard coral distribution of geomorphic and ecological zones, essential for reefs management in the context of global warming and ocean acidification, is not well documented. We analyzed data from field surveys, Landsat-8 and GF-1 images to map the distribution of hard coral within geomorphic zones and reef flat ecological zones. In situ surveys conducted in June 2014 on nine reefs provided a complete picture of reef status with regard to live coral diversity, evenness of coral cover and reef health (live versus dead cover) for the Xisha Islands. Mean coral cover was 12.5% in 2014 and damaged reefs seemed to show signs of recovery. Coral cover in sheltered habitats such as lagoon patch reefs and biotic dense zones of reef flats was higher, but there were large regional differences and low diversity. In contrast, the more exposed reef slopes had high coral diversity, along with high and more equal distributions of coral cover. Mean hard coral cover of other zones was <10%. The total Xisha reef system was estimated to cover 1 060 km2, and the emergent reefs covered 787 m2. Hard corals of emergent reefs were considered to cover 97 km2. The biotic dense zone of the reef flat was a very common zone on all simple atolls, especially the broader northern reef flats. The total cover of live and dead coral can reach above 70% in this zone, showing an equilibrium between live and dead coral as opposed to coral and algae. This information regarding the spatial distribution of hard coral can support and inform the management of Xisha reef ecosystems.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saller, A.H.; Schlanger, S.O.

Two wells drilled along the margin of Enewetak Atoll penetrated approximately 1000 m of upper Eocene, Oligocene, and lower Miocene carbonates. Strontium isotope stratigraphy indicates relatively continuous deposition of carbonate from 40 Ma to 20 Ma. Depositional environments show a gradual basinward progradation of facies with slope carbonates passing upward into fore-reef, reef, back-reef, and lagoonal carbonates. Slope strata contain wackestones and packstones with submarine-cemented lithoclasts, coral, coralline algae fragments, benthic rotaline forams, planktonic forams, and echinoderm fragments. Fore-reef strata are dominantly packstones and boundstones containing large pieces of coral, abundant benthic forams, coralline algae fragments, stromatoporoids( ), and minormore » planktonic forams. Reef and near-reef sediments include coralgal boundstones and grainstones with abundant benthic forams. Halimeda and miliolid forams are common in lagoonward parts of the back reef. Sponge borings, geopetal structures, and fractures are common in reef and fore-reef strata. Lagoonal strata are wackestones and packstones with common mollusks, coral, coralline algae, and benthic forams (rotaline and miliolid). Diagenesis has extensively altered strata near the atoll margin. Aragonite dissolution and calcite cements (radiaxial and cloudy prismatic) are abundant in fore-reef, reef, and some back-reef strata. Petrographic and geochemical data indicate aragonite dissolution and calcite cementation in seawater at burial depths of 100 to 300 m. Dolomite occurs in slope and deeply buried reefal carbonates. Most dolomitization occurred at burial depths of more than 1000 m in cool marine waters circulating through the atoll. lagoonal strata are not significantly altered by marine diagenesis and still contain abundant primary aragonite and magnesium calcite.« less

Biogeochemical typology and temporal variability of lagoon waters in a coral reef ecosystem subject to terrigeneous and anthropogenic inputs (New Caledonia).

PubMed

Fichez, R; Chifflet, S; Douillet, P; Gérard, P; Gutierrez, F; Jouon, A; Ouillon, S; Grenz, C

2010-01-01

Considering the growing concern about the impact of anthropogenic inputs on coral reefs and coral reef lagoons, surprisingly little attention has been given to the relationship between those inputs and the trophic status of lagoon waters. The present paper describes the distribution of biogeochemical parameters in the coral reef lagoon of New Caledonia where environmental conditions allegedly range from pristine oligotrophic to anthropogenically influenced. The study objectives were to: (i) identify terrigeneous and anthropogenic inputs and propose a typology of lagoon waters, (ii) determine temporal variability of water biogeochemical parameters at time-scales ranging from hours to seasons. Combined ACP-cluster analyses revealed that over the 2000 km(2) lagoon area around the city of Nouméa, "natural" terrigeneous versus oceanic influences affecting all stations only accounted for less than 20% of the spatial variability whereas 60% of that spatial variability could be attributed to significant eutrophication of a limited number of inshore stations. ACP analysis allowed to unambiguously discriminating between the natural trophic enrichment along the offshore-inshore gradient and anthropogenically induced eutrophication. High temporal variability in dissolved inorganic nutrients concentrations strongly hindered their use as indicators of environmental status. Due to longer turn over time, particulate organic material and more specifically chlorophyll a appeared as more reliable nonconservative tracer of trophic status. Results further provided evidence that ENSO occurrences might temporarily lower the trophic status of the New Caledonia lagoon. It is concluded that, due to such high frequency temporal variability, the use of biogeochemical parameters in environmental surveys require adapted sampling strategies, data management and environmental alert methods. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Evaluating the human impact on groundwater quality discharging into a coastal reef lagoon

NASA Astrophysics Data System (ADS)

Rebolledo-Vieyra, M.; Hernandez-Terrones, L.; Soto, M.; Lecossec, A.; Monroy-Rios, E.

2008-12-01

The Eastern coast of the Yucatan Peninsula has the fastest growth rate in Mexico and groundwater is the only source of drinking water in the region. The consequences of the lack of proper infrastructure to collect and treat wastewater and the impact of human activities on the quality of groundwater are addressed. The groundwater in the coastal aquifer of Quintana Roo (SE Mexico) discharges directly into the ocean. In addition, the coral reef of the Eastern Yucatan Peninsula is part of the Mesoamerican Coral Reef System, one of the largest in the world. The interaction of the reef-lagoon hydraulics with the coastal aquifer of Puerto Morelos (NE Yucatan Peninsula), and a major input of NH4, SO4, SiO2, as a consequence of the use of septic tanks and the lack of modern wastewater treatment plants are presented. No seasonal parameters differences were observed, suggesting that groundwater composition reaching the reef lagoon is not changing seasonally. A conceptual model of the coastal aquifer was developed, in order to explain how the human activities are impacting directly on the groundwater quality that, potentially, will have a direct impact on the coral reef. The protection and conservation of coral reefs must be directly related with a policy of sound management of coastal aquifers and wastewater treatment.

Development of Miocene-Pliocene reef trend, St. Croix, U. S. Virgin Islands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gill, I.; Eby, D.E.; Hubbard, D.K.

1988-01-01

The Miocene-Pliocene reef trend on St. Croix, U.S. Virgin Islands, rims the present southern western coasts of the island and includes accompanying lagoonal and forereef facies. The reef trend was established on a foram-algal bank facies that represents basinal shallowing from the deep-water pelagic and hemipelagic facies of the Miocene Kingshill Limestone. Information on facies distribution and thickness is derived from rock exposures and 22 test wells drilled to a maximum depth of 91 m. The greatest thickness of the reef facies exists in a subsidiary graben on the south coast of St. Croix. The thickness of the reef sectionmore » in this locality is due to preservation of the section in a downdropped block. Reef faunas include extant corals, as well as several extinct genera. Extant corals (e.g. Montastrea annularis, Diploria sp., and Porites porites) and extinct corals (e.g., Stylophora affinis, Antillea bilobata, and Thysanus sp.) are the main reef frame-builders. Coralline algea and large benthic foraminifera are significant contributors to the sediments both prior to and during scleractinian reef growth. Dolomitization and calcite cementation occur prominantly in an area corresponding to a Holocene lagoon. The spatial distribution of the dolomite suggests that the lagoon is a Tertiary feature directly related to the dolomitization process. Stable isotopic values suggest dolomitization of fluids of elevated salinity.« less

Density of Diadema antillarum (Echinodermata: Echinoidea) on live coral patch reefs and dead Acropora cervicornis rubble patches near Loggerhead Key, Dry Tortugas National Park, Florida, USA

EPA Science Inventory

Density of adult Diadema antillarum was assessed on live coral patch reefs and dead Acropora cervicornis rubble patches next to Loggerhead Key, Dry Tortugas National Park, Florida, USA in June 2009. Mean density on live coral patch reefs (0.49 individuals m-2) was not statistical...

Spatial and size-frequency distribution of Acropora (Cnidaria: Scleractinia) species in Chinchorro Bank, Mexican Caribbean: implications for management

NASA Astrophysics Data System (ADS)

Vega-Zepeda, A.; Hernández-Arana, H.; Carricart-Ganivet, J. P.

2007-09-01

The Mexican Government decreed Chinchorro Bank reef as a Biosphere Reserve in 1996. The aim of this study was to evaluate the spatial and size-frequency distribution of Acropora spp. in order to provide further knowledge and tools to enhance management. A field survey was conducted, within six regions, to locate and measure Acropora patches in the reef lagoon. Density, colony size and living tissue cover of Acropora colonies were evaluated using the line-intercept transect technique, combining direct observations and video transects. The results showed that Acropora spp. was preferentially distributed in the southern regions; where cover and density were high. Based on these results and considering that Acropora spp. produces landscape heterogeneity, which in turn generates shelter for other species, including some of considerable economic importance, then at least the South East region should be considered as a key area for Acropora species conservation, and should be included in the Chinchorro Bank management plan.

Effects of terrestrial runoff on the coral communities in Santiago Bay, Colima, Mexican Pacific Coast.

PubMed

Liñán-Cabello, Marco Agustín; Olivos-Ortiz, Aramis; Quijano-Scheggia, Sonia; Muñiz Anguiano, Daniela; Reséndiz-Flores, María Luisa; Ortega-Ortíz, Christian D

2016-09-01

Coral reef ecosystems are under stress of different origins, from factors including sedimentation, fragmentation, overfishing, and tourism, depending on their geographical location, depth, and proximity to recreation areas. In this study of Juluapan Lagoon, we examined the relationship between various water-quality attributes and the status indicators of the coral community at La Boquita reef. During 2011 (12 months of sampling), six monitoring stations in the Juluapan lagoon were established in order to observe the gradient of the distribution of the physicochemical parameters: three stations on the upper part, or BI, (S4 to S6) and three more in the lower part, or BII, (S1 to S3). A control station (CS) was located in the coral reef close to the lagoon channel, and where dissolved inorganic nutrients and cellular carbon content were determined. Additionally, we considered the monitoring of three of the eight largest coral structures/headlands of this community: the first was the station closest to the channel communicating with Juluapan lagoon (C1), the second was in the intermediate region with respect to that lagoon (C2), and the third was farthest from the channel (C3). Three line intercept transects (LIT) 30 m in length and perpendicular to the coast provenance were established in each station, and the parameters indicative of the status of corals were evaluated in an area of 60 m2 on each transect (180 m2 by the station). Turbidity, evidence of fishing, signs of settling, algal coverage, abundance of fish, rate of sediment, and coral health records (as for CoralWach chart) were determined in situ and from digital photographs and videos. Considering various community status indicators used in the reef area, we could recognize a state of general deterioration, which was reflected in the loss of 17 % of coral coverage. The main anthropogenic disturbances in adjacent areas to La Boquita reef included wastewater discharges into the lagoon, tourist developments in the coastal zone, deforestation and erosion resulting from inappropriate development, and the runoff of nutrients from agricultural lands nearby the lagoon. All these significantly contributed to the nutrient-enriched waters of the lagoon, especially in summer, with negative effects on the coral community. Continued exposure to these factors, coupled with the lack of control over other anthropogenic components, has promoted the maintenance of a chronic stress state in the studied coral community. Our findings highlight the need for the development of appropriate coastal management and conservation policies for the coral reefs of the Mexican Pacific Coast.

Spatial variability of sediment transport processes over intra‐ and subtidal timescales within a fringing coral reef system

USGS Publications Warehouse

Pomeroy, Andrew; Lowe, Ryan J.; Ghisalberti, Marco; Winter, Gundula; Storlazzi, Curt D.; Cuttler, Michael V. W.

2018-01-01

Sediment produced on fringing coral reefs that is transported along the bed or in suspension affects ecological reef communities as well as the morphological development of the reef, lagoon, and adjacent shoreline. This study quantified the physical process contribution and relative importance of incident waves, infragravity waves, and mean currents to the spatial and temporal variability of sediment in suspension. Estimates of bed shear stresses demonstrate that incident waves are the key driver of the SSC variability spatially (reef flat, lagoon, and channels) but cannot not fully describe the SSC variability alone. The comparatively small but statistically significant contribution to the bed shear stress by infragravity waves and currents, along with the spatial availability of sediment of a suitable size and volume, is also important. Although intra‐tidal variability in SSC occurs in the different reef zones, the majority of the variability occurs over longer slowly varying (subtidal) time scales, which is related to the arrival of large incident waves at a reef location. The predominant flow pathway, which can transport suspended sediment, consists of cross‐reef flow across the reef flat that diverges in the lagoon and returns offshore through channels. This pathway is primarily due to subtidal variations in wave‐driven flows, but can also be driven alongshore by wind stresses when the incident waves are small. Higher frequency (intra‐tidal) current variability also occur due to both tidal flows, as well as variations in the water depth that influence wave transmission across the reef and wave‐driven currents.

Coping with potential bi-parental inbreeding: limited pollen and seed dispersal and large genets in the dioecious marine angiosperm Thalassia testudinum.

PubMed

Van Tussenbroek, Brigitta Ine; Valdivia-Carrillo, Tania; Rodríguez-Virgen, Irene Teresa; Sanabria-Alcaraz, Sylvia Nashieli Marisela; Jiménez-Durán, Karina; Van Dijk, Kor Jent; Marquez-Guzmán, Guadalupe Judith

2016-08-01

The high prevalence of dioecy in marine angiosperms or seagrasses (>50% of all species) is thought to enforce cross-fertilization. However, seagrasses are clonal plants, and they may still be subject to sibling-mating or bi-parental inbreeding if the genetic neighborhood is smaller than the size of the genets. We tested this by determining the genetic neighborhoods of the dioecious seagrass Thalassia testudinum at two sites (Back-Reef and Mid-Lagoon) in Puerto Morelos Reef Lagoon, Mexico, by measuring dispersal of pollen and seeds in situ, and by fine-scale spatial autocorrelation analysis with eight polymorphic microsatellite DNA markers. Prevalence of inbreeding was verified by estimating pairwise kinship coefficients; and by analysing the genotypes of seedlings grown from seeds in mesocosms. Average dispersal of pollen was 0.3-1.6 m (max. 4.8 m) and of seeds was 0.3-0.4 m (max. 1.8 m), resulting in a neighborhood area of 7.4 m 2 (range 3.4-11.4 m 2 ) at Back-Reef and 1.9 (range 1.87-1.92 m 2 ) at Mid-Lagoon. Neighborhood area (Na) derived from spatial autocorrelation was 0.1-20.5 m 2 at Back-Reef and 0.1-16.9 m 2 at Mid-Lagoon. Maximal extensions of the genets, in 19 × 30 m plots, were 19.2 m (median 7.5 m) and 10.8 m (median 4.8 m) at Back-Reef and Mid-Lagoon. There was no indication of deficit or excess of heterozygotes nor were coefficients of inbreeding ( F IS ) significant. The seedlings did not show statistically significant deficit of heterozygotes (except for 1 locus at Back-Reef). Contrary to our expectations, we did not find evidence of bi-parental inbreeding in this dioecious seagrass with large genets but small genetic neighborhoods. Proposed mechanisms to avoid bi-parental inbreeding are possible selection against homozygotes during fecundation or ovule development. Additionally, the genets grew highly dispersed (aggregation index Ac was 0.09 and 0.10 for Back-Reef and Mid-Lagoon, respectively); such highly dispersed guerrilla-like clonal growth form likely increases the probability of crossing between different potentially unrelated genets.

Living in the Past: Phylogeography and Population Histories of Indo-Pacific Wrasses (Genus Halichoeres) in Shallow Lagoons versus Outer Reef Slopes

PubMed Central

Ludt, William B.; Bernal, Moisés A.; Bowen, Brian W.; Rocha, Luiz A.

2012-01-01

Sea level fluctuations during glacial cycles affect the distribution of shallow marine biota, exposing the continental shelf on a global scale, and displacing coral reef habitat to steep slopes on oceanic islands. In these circumstances we expect that species inhabiting lagoons should show shallow genetic architecture relative to species inhabiting more stable outer reefs. Here we test this expectation on an ocean-basin scale with four wrasses (genus Halichoeres): H. claudia (N = 194, with ocean-wide distribution) and H. ornatissimus (N = 346, a Hawaiian endemic) inhabit seaward reef slopes, whereas H. trimaculatus (N = 239) and H. margaritaceus (N = 118) inhabit lagoons and shallow habitats throughout the Pacific. Two mitochondrial markers (cytochrome oxidase I and control region) were sequenced to resolve population structure and history of each species. Haplotype and nucleotide diversity were similar among all four species. The outer reef species showed significantly less population structure, consistent with longer pelagic larval durations. Mismatch distributions and significant negative Fu’s F values indicate Pleistocene population expansion for all species, and (contrary to expectations) shallower histories in the outer slope species. We conclude that lagoonal wrasses may persist through glacial habitat disruptions, but are restricted to refugia during lower sea level stands. In contrast, outer reef slope species have homogeneous and well-connected populations through their entire ranges regardless of sea level fluctuations. These findings contradict the hypothesis that shallow species are less genetically diverse as a consequence of glacial cycles. PMID:22701597

Reef Development on Artificial Patch Reefs in Shallow Water of Panjang Island, Central Java

NASA Astrophysics Data System (ADS)

Munasik; Sugiyanto; Sugianto, Denny N.; Sabdono, Agus

2018-02-01

Reef restoration methods are generally developed by propagation of coral fragments, coral recruits and provide substrate for coral attachment using artificial reefs (ARs). ARs have been widely applied as a tool for reef restoration in degraded natural reefs. Successful of coral restoration is determined by reef development such as increasing coral biomass, natural of coral recruits and fauna associated. Artificial Patch Reefs (APRs) is designed by combined of artificial reefs and coral transplantation and constructed by modular circular structures in shape, were deployed from small boats by scuba divers, and are suitable near natural reefs for shallow water with low visibility of Panjang Island, Central Java. Branching corals of Acropora aspera, Montipora digitata and Porites cylindrica fragments were transplanted on to each module of two units of artificial patch reefs in different periods. Coral fragments of Acropora evolved high survival and high growth, Porites fragments have moderate survival and low growth, while fragment of Montipora show in low survival and moderate growth. Within 19 to 22 months of APRs deployment, scleractinian corals were recruited on the surface of artificial patch reef substrates. The most recruits abundant was Montastrea, followed by Poritids, Pocilloporids, and Acroporids. We conclude that artificial patch reefs with developed by coral fragments and natural coral recruitment is one of an alternative rehabilitation method in shallow reef with low visibility.

Abnormally high phytoplankton biomass near the lagoon mouth in the Huangyan Atoll, South China Sea.

PubMed

Ke, Zhixin; Liu, Huajian; Wang, Junxing; Liu, Jiaxing; Tan, Yehui

2016-11-15

Nutrient concentration and phytoplankton biomass were investigated in Huangyan Atoll in May 2015. The concentrations of nutrients were very low, and dissolved inorganic nitrogen was composed mainly of ammonia. Nitrogen likely was the primary limiting factor for phytoplankton growth. The spatial variation of phytoplankton biomass was significant among the lagoon, reef flats, and outer reef slopes. Extremely high chlorophyll a concentration and micro-phytoplankton abundance were found in the region near the lagoon mouth. This high phytoplankton biomass might be due to nutrient input from fishing vessels and phytoplankton aggregation driven by the southwestern wind. Our results indicate that phytoplankton biomass could be a reliable indicator of habitat differences in this coral reef ecosystem, and micro-phytoplankton seems to be more sensitive to nutrient input than pico-phytoplankton. Copyright © 2016. Published by Elsevier Ltd.

Lagoon islets as indicators of recent environmental changes in the South Pacific - The New Caledonian example

NASA Astrophysics Data System (ADS)

Garcin, Manuel; Vendé-Leclerc, Myriam; Maurizot, Pierre; Le Cozannet, Gonéri; Robineau, Bernard; Nicolae-Lerma, Alexandre

2016-07-01

The question of the impacts of climate change and sea level rise on small islands is currently much discussed. The many thousands of Pacific islands in their different contexts (geodynamic, climatic, etc.) and the insufficient data available explain why it is difficult to clearly discern the specific role of climate change in the recent evolution of these islands. To address this question, we investigated the recent changes affecting 21 islets in New Caledonia's lagoon. These islets are either located on small patch-reefs inside the New Caledonia Island lagoon or lie directly on the barrier reef. Based on the studies we conducted (field surveys, reconstruction of changes in the islets over the last decades, shoreline changes) we were able to define a typology of the islets that includes 6 stages and a life expectancy index. Using the life expectancy index, we found that of the 21 islets studied, 19% are in a highly critical situation, meaning they are very likely to be endangered in the short term (within the next few years), 9.5% are in a critical situation, i.e., likely to disappear in the near future and very likely to disappear in the medium term (next few decades), 19% are evolving rapidly, which could lead to their disappearance in the medium term but not in the short term, 9.5% are not endangered in the short and medium term and 43% are not endangered at all (stable or accreting, large area, relatively higher altitude). In this context, the rise in sea level induced by climate change is an adverse factor which is likely to lower the resilience of the islets to erosion processes. Other factors like the degradation of the reef ecosystem due to variations in ocean salinity, temperature and acidity, lower sediment stocks on the beaches and foreshores, human visitors, coastal development and so on are other adverse factors that could modify the capacity for resilience of these islets. Due to their variety and sensitivity, New Caledonia's islets could thus serve as integrative indicators of environmental and climatic change for New Caledonia.

Unusually high (210)Po activities in the surface water of the Zhubi Coral Reef Lagoon in the South China Sea.

PubMed

Yang, Weifeng; Huang, Yipu; Chen, Min; Qiu, Yusheng; Li, Hongbin; Zhang, Lei

2011-10-01

Recent researches revealed the exciting application of (210)Po in tracing carbon and nitrogen cycling in the coral reef system. In order to quantify the recycling of particulate organic nitrogen (PON), both (210)Po and (210)Pb were examined at both high and low tides in the Zhubi Coral Reef lagoon, the South China Sea. Unusually, much higher (210)Po activities and (210)Po/(210)Pb ratios, in comparison with those found in the open seawater and the lagoon subsurface water, showed additional input of (210)Po besides production from in situ(210)Pb in the lagoon surface water. Statistical analysis identified that the reef flat seawater was the additional (210)Po source. Based on a mass balance model, the input rates of (210)Po varied from 0.04 Bq m(-3)year(-1) to 8.41 Bq m(-3)year(-1). On average, the additional (210)Po contributed more than 60% of the total (210)Po. The particulate (210)Po significantly correlated with the concentrations of PON, indicating that diffusion of (210)Po from sediment could be used to quantify the recycling of nitrogen. The average input rate of nitrogen was 16 mmol m(-3)year(-1), which can support up to 11% of the primary production rate. These results suggested that the unusual behavior of (210)Po could provide new insight into the nitrogen recycling in the coral reef system. Copyright © 2011 Elsevier B.V. All rights reserved.

Wave-driven Hydrodynamics for Different Reef Geometries and Roughness Scenarios

NASA Astrophysics Data System (ADS)

Franklin, G. L.; Marino-Tapia, I.; Torres-Freyermuth, A.

2013-05-01

In fringing reef systems where a shallow lagoon is present behind the reef crest, wave breaking appears to dominate circulation, controlling numerous key processes such as the transport and dispersion of larvae, nutrients and sediments. Despite their importance, there is a need for more detailed knowledge on the hydrodynamic processes that take place within the surf zone of these systems and the effects different combinations of geometries and roughness have on them. The present study focuses on the use of two-dimensional (2DV) numerical model simulations and data obtained during a field campaign in Puerto Morelos, Quintana Roo, Mexico to better understand the detailed surf zone processes that occur over a fringing reef. The model used is Cornell Breaking Wave and Structures (COBRAS), which solves Reynolds-Averaged Navier-Stokes (RANS) equations. Reef geometries implemented in the model include a reef flat and two different reef crests. The effect of roughness on wave setup, radiation stress, mean flows, and cross-shore spectral evolution for the model results was studied using different roughness coefficients (Nikuradse) and a bathymetric profile obtained in the field using the bottom track option of an Acoustic Doppler Current Profiler. Field data were also analysed for the configuration and roughness of Puerto Morelos. Model results reveal that for all profiles wave setup increased significantly (~22%) with increasing bed roughness, in agreement with previous findings for sandy beaches.For all wave heights and periods studied, increasing roughness also affected spectral wave evolution across the reef, with a significant reduction in energy, particularly at infragravity frequencies. The presence of a reef crest in the profile resulted in differences in behaviour at infragravity frequencies. For example, preliminary results suggest that there is a shift towards higher frequencies as waves progress into the lagoon when a crest is present, something that does not appear to occur over the reef flat. Time-averaged velocities exhibited a dominant onshore flow due to waves at the surface, as is generally reported for coral reefs. Model results also suggest the presence of offshore velocities, which were slightly greater over the reef flat compared to the reef crest. Maximum offshore velocities appear to be more localised in the case of the reef flat whereas they extended over a larger area in the case of the reef crest. In all cases, increased roughness resulted in reduced velocities. These results are important since they concern processes that affect the circulation within the lagoon, which has implications in terms of the lagoon's residence time and hence heat dispersion and exposure to pollutants.

Turbulence characteristics inferred from time-lagged satellite imagery of surface algae in a shallow tidal sea

NASA Astrophysics Data System (ADS)

Marmorino, George O.; Smith, Geoffrey B.; Miller, W. D.

2017-09-01

A pair of time-lagged satellite images of surface algae in the Great Barrier Reef lagoon is used to investigate characteristics of the horizontal velocity field at a spatial resolution as small as 4 m. A distinctive feature is the occurrence of surface patches that are relatively clear of algae and which grow in size. These patches are interpreted as resulting from the horizontally diverging motion associated with boils. The surface divergence in such boils can be as large as 0.01 s-1, as deduced directly from the imagery. Overall, root-mean-squared values of divergence, vorticity, and strain rate are 45, 58, and 170, respectively, when normalized by the Coriolis parameter. By observing the algae and its fluid environment simultaneously, the analysis thus provides a glimpse of how underlying hydrodynamic processes help shape the distribution of surface algae - under the calm winds that favor the formation of dense surface aggregations.

Growth, Survival and Reproduction of the Giant Clam Tridacna maxima (Röding 1798, Bivalvia) in Two Contrasting Lagoons in French Polynesia

PubMed Central

Van Wynsberge, Simon; Andréfouët, Serge; Gaertner-Mazouni, Nabila; Wabnitz, Colette C. C.; Menoud, Mathilde; Le Moullac, Gilles; Levy, Peva; Gilbert, Antoine; Remoissenet, Georges

2017-01-01

Shell growth, reproduction, and natural mortality of the giant clam Tridacna maxima were characterized over a two-year-period in the lagoon of the high island of Tubuai (Austral Archipelago) and in the semi-closed lagoon of Tatakoto (Tuamotu Archipelago) in French Polynesia. We also recorded temperature, water level, tidal slope, tidal range, and mean wave height in both lagoons. Lower lagoon aperture and exposure to oceanic swells at Tatakoto than at Tubuai was responsible for lower lagoon water renewal, as well as higher variability in temperature and water level at Tatakoto across the studied period. These different environmental conditions had an impact on giant clams. Firstly, spawning events in the lagoon of Tatakoto, detected by gonad maturity indices in June and July 2014, were timed with high oceanic water inflow and a decrease in lagoon water temperature. Secondly, temperature explained differences in shell growth rates between seasons and lagoons, generating different growth curves for the two sites. Thirdly, local mortality rates were also found to likely be related to water renewal patterns. In conclusion, our study suggests that reef aperture and lagoon water renewal rates play an integral role in giant clam life history, with significant differences in rates of shell growth, mortality and fertility found between open versus semi-closed atoll lagoons in coral reef ecosystems. PMID:28118406

Can reef islands keep up with sea level? Exploring the interplay between sea-level rise, sediment supply, and overwash processes

NASA Astrophysics Data System (ADS)

Lorenzo-Trueba, J.

2016-02-01

Coral reef islands are accumulations of carbonate sediment deposited subaerially atop coral reef platforms. We hypothesize that the long-term evolution of reef islands is primarily controlled by the interplay between sea-level rise, sediment supply, and sediment overwash. Reef islands are supplied with sediment from offshore, in the form of reworked coral skeletons that originate at the reef edge and are carried onto the reef platform by waves, as well as in situ production on the reef flat itself. However, the primary mechanism that allows reef islands to keep pace with sea level is storm overwash, which enables the vertical transport of sediment from the periphery to the top of the island. Given the current lack of understanding on how production and overwash processes interact, we have constructed a morphodynamic model to elucidate and quantify how reef islands may respond to sea-level rise and changes in sediment production. Model results demonstrate that even if reef islands can remain subaerial over the coming century, this will require significant deposition of sediment atop the island and, in many cases, the island is expected to roll considerably over itself; both of these morphologic changes will negatively affect homes and infrastructure atop these islands. The model also suggests that as reef islands approach the lagoon edge of the reef platform, shoreline erosion and island drowning can be enhanced as sediment overwashes into the lagoon. Interestingly, this situation can only be avoided if either a high offshore sediment supply bulwarks the island in place or the system undergoes similar rates of overwash sedimentation from both the ocean and the lagoon sides. The model also allows us to explore the potential for increased overwash with increased storminess, increases in sediment supply due to bleaching or disturbance, or reduction of sediment supply as a result of reduced calcification rates due to ocean acidification.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Saller, A.H.; Schlanger, S.O.

Two wells drilled along the margin of Enewetak Atoll penetrated approximately 1,000 m of upper eocene, Oligocene, and lower Miocene carbonates. STrontium isotope stratigraphy indicates relatively continuous deposition of carbonate from 40 Ma to 20 Ma. Depositional environments show a gradual basinward progradation of facies with slope carbonates passing upward into fore-reef, reef, back-reef, and lagoonal carbonates. Slope strata contain wackestones and packstones with submarine-cemented lithoclasts, coral, coralline algae fragments, benthic rotaline forams, planktonic forams, and echinoderm fragments. Fore-reef strata are dominantly packstones and boundstones containing large pieces of coral, abundant benthic forams, coralline algae fragments, stromatoporoids(.), and minor planktonicmore » forams. Reef and near-reef sediments include coralgal boundstones and grainstones with abundant benthic forams. Halimeda and miliolid forams are common in lagoonward parts of the back reef. Sponge borings, geopetal structures, and fractures are common in reef and fore-reef strata. Lagoonal strata are wackestones and packstones with common mollusks, coral, coralline algae, and benthic forams (rotaline and miliolid). Diagenesis has extensively altered strata near the atoll margin. Aragonite dissolution and calcite cements (radiaxial and cloudy prismatic are abundant in fore-reef, reef, and some back-reef strata). Petrographic and geochemical data indicate arogonite dissolution and calcite cementation in seawater at burial depths of 100 to 300 m. Dolomite occurs in slope and deeply buried reefal carbonates.« less

Coral reef sedimentation on Rodrigues and the Western Indian Ocean and its impact on the carbon cycle.

PubMed

Rees, Siwan A; Opdyke, Bradley N; Wilson, Paul A; Fifield, L Keith

2005-01-15

Coral reefs in the southwest Indian Ocean cover an area of ca. 18,530 km2 compared with a global reef area of nearly 300,000 km2. These regions are important as fishing grounds, tourist attractions and as a significant component of the global carbon cycle. The mass of calcium carbonate stored within Holocene neritic sediments is a number that we are only now beginning to quantify with any confidence, in stark contrast to the mass and sedimentation rates associated with pelagic calcium carbonate, which have been relatively well defined for decades. We report new data that demonstrate that the reefs at Rodrigues, like those at Reunion and Mauritius, only reached a mature state (reached sea level) by 2-3 ka: thousands of years later than most of the reefs in the Australasian region. Yet field observations show that the large lagoon at Rodrigues is already completely full of carbonate detritus (typical lagoon depth less than 1 m at low spring tide). The presence of aeolian dunes at Rodrigues indicates periodic exposure of past lagoons throughout the Pleistocene. The absence of elevated Pleistocene reef deposits on the island indicates that the island has not been uplifted. Most Holocene reefs are between 15 and 20 m in thickness and those in the southwest Indian Ocean appear to be consistent with this observation. We support the view that the CO2 flux associated with coral-reef growth acts as a climate change amplifier during deglaciation, adding CO2 to a warming world. southwest Indian Ocean reefs could have added 7-10% to this global flux during the Holocene.

Marine debris accumulation in the Northwestern Hawaiian Islands: an examination of rates and processes.

PubMed

Dameron, Oliver J; Parke, Michael; Albins, Mark A; Brainard, Russell

2007-04-01

Large amounts of derelict fishing gear accumulate and cause damage to shallow coral reefs of the Northwestern Hawaiian Islands (NWHI). To facilitate maintenance of reefs cleaned during 1996-2005 removal efforts, we identify likely high-density debris areas by assessing reef characteristics (depth, benthic habitat type, and energy regime) that influence sub-regional debris accumulation. Previously cleaned backreef and lagoonal reefs at two NWHI locations were resurveyed for accumulated debris using two survey methods. Accumulated debris densities and weights were found to be greater in lagoonal reef areas. Sample weight-based debris densities are extrapolated to similar habitats throughout the NWHI using a spatial 'net habitat' dataset created by generalizing IKONOS satellite derivatives for depth and habitat classification. Prediction accuracy for this dataset is tested using historical debris point data. Annual NWHI debris accumulation is estimated to be 52.0 metric tonnes. For planning purposes, individual NWHI atolls/reefs are allotted a proportion of this total.

Dongsha Atoll: A potential thermal refuge for reef-building corals in the South China Sea.

PubMed

Tkachenko, Konstantin S; Soong, Keryea

2017-06-01

Dongsha Atoll (also known as the Pratas Islands), the northernmost atoll in the South China Sea, experiences two contrasting physical phenomena: repetitive anomalies of the sea surface temperature exceeding the coral bleaching threshold and regular effects of the world's strongest internal waves resulting in the rhythmic upwelling of cold deep waters at the outer reef slopes of the atoll. This unique combination may result in significant differences in coral species composition and structure between the lagoon and forereef. Surveys conducted in August-September 2016 at 12 study sites in the 2-15 m depth range at Dongsha Atoll revealed a clear spatial separation between 'thermally-susceptible' stony coral genera, including Acropora, Pocillopora and Montipora, which mainly inhabited the forereef, and 'thermally-resistant' genera, including massive Porites, foliaceous Echinopora, Pavona and Turbinaria, which mainly resided in the lagoon. The mean coral cover and species richness on the forereef were respectively 1.8 and 1.4 times higher than those in the lagoon (61.3% and 98 species on the forereef vs. 34.2% and 69 species in the lagoon). Coral mortality rates, expressed as the ratio of dead to live stony corals, showed the same pattern (0.4 in the lagoon vs. 0.009 on the forereef). Furthermore, in a laboratory experiment, 'thermally-susceptible' taxa from the lagoon, (e.g. Pocillopora verrucosa and P. damicornis), exhibited higher resistance to bleaching than did their counterparts from the forereef. The present findings indicate that Dongsha Atoll is a potential thermal refuge for reef-building corals in the northern South China Sea and reveal the development of resilience and resistance to bleaching in coral communities of the lagoon. Copyright © 2017 Elsevier Ltd. All rights reserved.

Airborne lidar sensing of massive stony coral colonies on patch reefs in the northern Florida reef tract

USGS Publications Warehouse

Brock, J.C.; Wright, C.W.; Kuffner, I.B.; Hernandez, R.; Thompson, P.

2006-01-01

In this study we examined the ability of the NASA Experimental Advanced Airborne Research Lidar (EAARL) to discriminate cluster zones of massive stony coral colonies on northern Florida reef tract (NFRT) patch reefs based on their topographic complexity (rugosity). Spatially dense EAARL laser submarine topographic soundings acquired in August 2002 were used to create a 1-m resolution digital rugosity map for adjacent NFRT study areas characterized by patch reefs (Region A) and diverse substratums (Region B). In both regions, sites with lidar-sensed rugosities above 1.2 were imaged by an along-track underwater videography system that incorporated the acquisition of instantaneous GPS positions. Subsequent manual interpretation of videotape segments was performed to identify substratum types that caused elevated lidar-sensed rugosity. Our study determined that massive coral colony formation, modified by subsequent physical and biological processes that breakdown patch reef framework, was the primary source of topographic complexity sensed by the EAARL in the NFRT. Sites recognized by lidar scanning to be topographically complex preferentially occurred around the margins of patch reefs, constituted a minor fraction of the reef system, and usually reflected the presence of massive coral colonies in cluster zones, or their derivatives created by mortality, bioerosion, and physical breakdown.

Correlation of Coral Bleaching Events and Remotely-Sensed Sea Surface Temperatures

DTIC Science & Technology

1994-05-19

water column. Diving on the reefs, they found significant tracts of bleached corals, zoanthids , gorgonians, and sea anemones (Bunckley-Williams and... zoanthids between May and July 1988 on shallow lagoonal reefs and rim margin reefs was the first indication of any sort of bleaching event at Bermuda

French Frigate Shoals reef health survey

USGS Publications Warehouse

Work, Thierry M.; Coles, Steve L.; Rameyer, Robert

2002-01-01

French Frigate Shoals consists of a large (31 nm) fringing reef partially enclosing a lagoon. A basalt pinnacle (La Perouse Pinnacle) arises approximately halfway between the two ends of the arcs of the fringing reefs. Tern Island is situated at the northern end of the lagoon and is surrounded by a dredged ship channel. The lagoon becomes progressively shallower from west to east and harbors a variety of marine life including corals, fish, marine mammals, and sea turtles (Amerson 1971). In 2000, an interagency survey of the northwestern Hawaiian Islands was done to document the fauna and flora in FFS (Maragos and Gulko, 2002). During that survey, 38 stations were examined, and 41 species of stony corals were documented, the most of any of the NW Hawaiian islands (Maragos and Gulko 2002). In some of these stations, corals with abnormalities were observed. The present study aimed to expand on the 2000 survey to evaluate the lesions in areas where they were documented.

Lagoons and Reefs of New Caledonia

NASA Image and Video Library

2011-04-20

NASA image acquired May 10, 2001 In July 2008, the United Nations Educational, Scientific, and Cultural Organization (UNESCO) added 27 new areas to its list of World Heritage sites. One of those areas included the lagoons of New Caledonia. Some 1,200 kilometers (750 miles) east of Australia, this French-governed archipelago contains the world’s third-largest coral reef structure. The coral reefs enclose the waters near the islands in shallow lagoons of impressive biodiversity. On May 10, 2001, the Enhanced Thematic Mapper Plus on NASA’s Landsat 7 satellite captured this image of Île Balabio, off the northern tip of Grande Terra, New Caledonia’s main island. In this natural-color image, the islands appear in shades of green and brown—mixtures of vegetation and bare ground. The surrounding waters range in color from pale aquamarine to deep blue, and the color differences result from varying depths. Over coral reef ridges and sand bars, the water is shallowest and palest in color. Darker shades of blue characterize deeper waters. Reef-enclosed, shallow waters surround Île Balabio, and a larger, semi-enclosed lagoon appears immediately east of that island. Immediately north of Grande Terra, unenclosed, deeper waters predominate. The coral reefs around New Caledonia support an unusual diversity of species, including large numbers of predators and big fish, turtles, and the world’s third-largest dugong population. NASA image created by Jesse Allen, using Landsat data provided by the United States Geological Survey. Caption by Michon Scott. Instrument: Landsat 7 - ETM+ Credit: NASA/GSFC/Landsat NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Join us on Facebook

Identifying nutrient sources to three lagoons at Ofu and Olosega, American Samoa using δ15N of benthic macroalgae

USGS Publications Warehouse

Garrison, Virginia H.; Kroeger, Kevin D.; Fenner, Douglas; Craig, Peter

2007-01-01

Degradation of nearshore habitats is a serious problem in some areas of American Samoa, such as in Pago Pago Harbor on Tutuila Island, and is a smaller but chronic problem in other areas. Sedimentation, pollution, nutrient enrichment from surface runoff or groundwater, and trampling are the major factors causing the changes (Peshut and Brooks, 2005). On the outer islands of Ofu and Olosega (Manu’a Islands; Fig. 1), there is an interesting contrast between relatively pristine lagoon habitats not far from comparatively degraded lagoon habitats. To’aga lagoon on the southeast side of Ofu Island (Fig. 1) has clear waters, a high diversity of corals and fishes, no human habitations, and an undeveloped watershed with no streams. To’aga lagoon is within the boundaries of the National Park of American Samoa and is the site of long-term research on coral reef resilience and global climate change. Only 3 km to the east of To’aga is a degraded lagoon that fronts Olosega Village. The Olosega lagoon is similar in size but has significantly less live coral than To’aga, and blooms of filamentous algae have been reported to cover the Olosega lagoon/reef flat bottom (unpublished data, PC; Fig. 2). The islands are influenced by the same regional-scale and biogeochemical regimes, and both islands are remnants of a volcanic caldera (Craig, 2005). Thus, local factors operating on the scale of a kilometer or less are thought to be driving the differences observed between lagoons. Land disturbance is limited to a road linking the villages, the clearing of vegetation for buildings, and two village dump sites located on the narrow strip of land between the steep slopes of the islands and the shoreline; there is no industry or associated pollution on either island. Cesspools are used for sewage disposal. Nutrient enrichment (from cesspools) of groundwater and the lagoon, as well as trampling during gleaning of reef organisms, are possible factors affecting the spatial relief and benthic composition of the lagoons. A pristine lagoon site (To’aga) and two that may be influenced by adjacent human populations (Ofu and Olosega Villages) were selected for study.

Diuron tolerance and potential degradation by pelagic microbiomes in the Great Barrier Reef lagoon

PubMed Central

Pantos, Olga; Morgan, Thomas C.; Rich, Virginia; Tonin, Hemerson; Bourne, David G.; Mercurio, Philip; Negri, Andrew P.; Tyson, Gene W.

2016-01-01

Diuron is a herbicide commonly used in agricultural areas where excess application causes it to leach into rivers, reach sensitive marine environments like the Great Barrier Reef (GBR) lagoon and pose risks to marine life. To investigate the impact of diuron on whole prokaryotic communities that underpin the marine food web and are integral to coral reef health, GBR lagoon water was incubated with diuron at environmentally-relevant concentration (8 µg/L), and sequenced at specific time points over the following year. 16S rRNA gene amplicon profiling revealed no significant short- or long-term effect of diuron on microbiome structure. The relative abundance of prokaryotic phototrophs was not significantly altered by diuron, which suggests that they were largely tolerant at this concentration. Assembly of a metagenome derived from waters sampled at a similar location in the GBR lagoon did not reveal the presence of mutations in the cyanobacterial photosystem that could explain diuron tolerance. However, resident phages displayed several variants of this gene and could potentially play a role in tolerance acquisition. Slow biodegradation of diuron was reported in the incubation flasks, but no correlation with the relative abundance of heterotrophs was evident. Analysis of metagenomic reads supports the hypothesis that previously uncharacterized hydrolases carried by low-abundance species may mediate herbicide degradation in the GBR lagoon. Overall, this study offers evidence that pelagic phototrophs of the GBR lagoon may be more tolerant of diuron than other tropical organisms, and that heterotrophs in the microbial seed bank may have the potential to degrade diuron and alleviate local anthropogenic stresses to inshore GBR ecosystems. PMID:26989611

Predictable spatial escapes from herbivory: how do these affect the evolution of herbivore resistance in tropical marine communities?

PubMed

Hay, Mark E

1984-11-01

Between-habitat differences in macrophyte consumption by herbivorous fishes were examined on three Caribbean and two Indian Ocean coral reefs. Transplanted sections of seagrasses were used as a bioassay to compare removal rates in reef-slope, reef-flat, sand-plain, and lagoon habitats. Herbivore susceptibility of fifty-two species of seaweeds from these habitats was also measured in the field. Seagrass consumption on shallow reef slopes was always significantly greater than on shallow reef flats, deep sand plains, or sandy lagoons. Reef-slope seaweeds were consistently resistant to herbivory while reef-flat seaweeds were consistently very susceptible to herbivory. This pattern supports the hypothesis that defenses against herbivores are costly in terms of fitness and are selected against in habitats with predictably low rates of herbivory.Sand-plain and lagoon seaweeds showed a mixed response when placed in habitats with high herbivore pressure; most fleshy red seaweeds were eaten rapidly, most fleshy green seaweeds were eaten at intermediate rates, and most calcified green seaweeds were avoided or eaten at very low rates. Differences in susceptibility between red and green seaweeds from sand-plain or lagoon habitats may result from differential competitive pressures experienced by these seaweed groups or from the differential probability of being encountered by herbivores. The susceptibility of a species to removal by herbivorous fishes was relatively consistent between reefs. Preferences of the sea urchin Diadema antillarum were also similar to those of the fish guilds.Unique secondary metabolites were characteristic of almost all of the most herbivore resistant seaweeds. However, some of the herbivore susceptible species also contain chemicals that have been proposed as defensive compounds. Genera such as Sargassum, Turbinaria, Thalassia, Halodule, and Thalassodendron, which produce polyphenolics or phenolic acids, were consumed at high to intermediate rates, suggesting that these compounds are not effective deterrents for some herbivorous fishes. Additionally, potential for the production of the compounds caulerpin, caulerpicin and caulerpenyne in various species of Caulerpa did not assure low susceptibility to herbivory.Heavily calcified seaweeds were very resistant to herbivory, but all of these species also produce toxic secondary metabolites which makes it difficult to distinguish between the effects of morphological and chemical defenses. Predictions of susceptibility to herbivory based on algal toughness and external morphology were of limited value in explaining differing resistances to herbivory.

Catastrophic impact of typhoon waves on coral communities in the Ryukyu Islands under global warming

NASA Astrophysics Data System (ADS)

Hongo, Chuki; Kawamata, Hideki; Goto, Kazuhisa

2012-06-01

Typhoon-generated storm waves generally cause mechanical damage to coral communities on present-day reefs, and the magnitude and extent of damage is predicted to increase in the near future as a result of global warming. Therefore, a comprehensive understanding of potential future scenarios of reef ecosystems is of prime interest. This study assesses the current status of coral communities on Ibaruma reef, Ryukyu Islands, on the basis of field observations, engineering and fluid dynamic models, and calculations of wave motion, and predicts the potential effects of a super-extreme typhoon (incident wave height,H = 20 m; wave period, T = 20 s) on the reef. On the present-day reef, massive corals occur in shallow lagoons and tabular corals occur from the reef crest to the reef slope. The observed distribution of corals, which is frequently attacked by moderate (H = 10 m, T = 10 s) and extreme (H = 10 m, T = 15 s) typhoons, is consistent with the predictions of engineering models. Moreover, this study indicates that if a super-extreme typhoon attacks the reef in the near future, massive corals will survive in the shallow lagoons but tabular corals on the reef crest and reef slope will be severely impacted. The findings imply that super-extreme typhoons will cause a loss of species diversity, as the tabular corals are important reef builders and are critical to the maintenance of reef ecosystems. Consequently, reef restoration is a key approach to maintaining reef ecosystems in the wake of super-extreme typhoons.

Effects of macroalgae on the recruitment, growth, and body condition of an invasive reef forming polychaete in a south-western Atlantic coastal lagoon

NASA Astrophysics Data System (ADS)

Bazterrica, María Cielo; Bruschetti, Carlos Martín; Alvarez, María Fernanda; Iribarne, Oscar; Botto, Florencia

2014-04-01

Species interactions could mediate species invasive processes. In Mar Chiquita coastal lagoon (37° 40‧S, 57° 23´W, Argentine), the invasive reef building polychaete Ficopomatus enigmaticus (Fauvel 1923) enhances the biomass of the red alga Polysiphonia subtilissima Montagne 1840 on reef surfaces, and excludes green macroalgae (mainly Cladophora sp. Kützing, 1843) from sediment between reefs. In turn, macroalgae could have several community structuring effects (e.g., as food or by competing for space). Therefore, macroalgae may affect F. enigmaticus. To evaluate this hypothesis we studied (1) the interaction between macroalgae and F. enigmaticus during the colonization of new substrates and (2) the effects of macroalgae on the recruitment, growth, and body condition of F. enigmaticus. Field sampling and experiments suggested a lack of competition on new substrates. However, there was a positive effect of macroalgae on F. enigmaticus during the warm season, since its recruitment, tube length, and body condition were higher in areas with macroalgae on reef surfaces. Considering that previous studies showed that reefs positively affect macroalgae, our results suggest that there is a positive feedback on F. enigmaticus created by macroalgae on established reefs and during the reefs' growing season. This interaction may contribute to the maintenance and growth of established reefs.

The influence of micro-topography and external bioerosion on coral-reef-building organisms: recruitment, community composition and carbonate production over time

NASA Astrophysics Data System (ADS)

Mallela, Jennie

2018-03-01

The continued health and function of tropical coral reefs is highly dependent on the ability of reef-building organisms to build large, complex, three-dimensional structures that continue to accrete and evolve over time. The recent deterioration of reef health globally, including loss of coral cover, has resulted in significant declines in architectural complexity at a large, reef-scape scale. Interestingly, the fine-scale role of micro-structure in initiating and facilitating future reef development and calcium carbonate production has largely been overlooked. In this study, experimental substrates with and without micro-ridges were deployed in the lagoon at One Tree Island for 34 months. This study assessed how the presence or absence of micro-ridges promoted recruitment by key reef-building sclerobionts (corals and encrusters) and their subsequent development at micro (mm) and macro (cm) scales. Experimental plates were examined after 11 and 34 months to assess whether long-term successional and calcification processes on different micro-topographies led to convergent or divergent communities over time. Sclerobionts were most prevalent in micro-grooves when they were available. Interestingly, in shallow lagoon reef sites characterised by shoals of small parrotfish and low urchin abundance, flat substrates were also successfully recruited to. Mean rates of carbonate production were 374 ± 154 (SD) g CaCO3 m-2 yr-1 within the lagoon. Substrates with micro-ridges were characterised by significantly greater rates of carbonate production than smooth substrates. The orientation of the substrate and period of immersion also significantly impacted rates of carbonate production, with CaCO3 on cryptic tiles increasing by 28% between 11 and 34 months. In contrast, rates on exposed tiles declined by 35% over the same time. In conclusion, even at sites characterised by small-sized parrotfish and low urchin density, micro-topography is an important settlement niche clearly favouring sclerobiont early life-history processes and subsequent carbonate production.

[Biomass and density of 2 seagrass species in southern Quintana Roo, Mexico].

PubMed

Gutiérrez-Aguirre, M A; de la Fuente-Betancourt, M G; Cervantes-Martínez, A

2000-01-01

The biomass and productivity of a seagrass community are useful for determining the ecological status of the coast. Leaf biomass and shoot density in beds of Thalassia testudinum Banks & Sol. ex K. D. Koenig, were compared for two environments in the Mexican Caribbean coast (N = 6 quadrants/site) in November 1998. Shoot and leaf biomass values were lower in the mangrove-associated meadow than in the reef lagoon meadow. This could be related to the higher percentage of epiphytes on the leaves. In addition, T. testudinum had more biomass than Syringodium filiforme Kütz in the reef lagoon.

Assessment of human activities impact on groundwater quality discharging into a reef lagoon

NASA Astrophysics Data System (ADS)

Rebolledo-Vieyra, M.; Hernandez, L.; Paytan, A.; Merino-Ibarra, M.; Lecossec, A.; Soto, M.

2010-03-01

The Eastern coast of the Yucatan Peninsula has the fastest growth rate in Mexico and groundwater is the only source of drinking water in the region. The consequences of the lack of proper infrastructure to collect and treat wastewater and the impact of human activities on the quality of groundwater are addressed. The groundwater in the coastal aquifer of Quintana Roo (SE Mexico) discharges directly into the ocean (Submarine Groundwater Discharges). In addition, the coral reef of the Eastern Yucatan Peninsula is part of the Mesoamerican Coral Reef System, one of the largest in the world. The interaction of the reef-lagoon hydraulics with the coastal aquifer of Puerto Morelos (NE Yucatan Peninsula), and a major input of NH4, SO4, SiO2, as a consequence of the use of septic tanks and the lack of modern wastewater treatment plants are presented. A conceptual model of the coastal aquifer was developed, in order to explain how the human activities are impacting directly on the groundwater quality that, potentially, will have a direct impact on the coral reef. The protection and conservation of coral reefs must be directly related with a policy of sound management of coastal aquifers and wastewater treatment.

What doesn't kill you makes you wary? Effect of repeated culling on the behaviour of an invasive predator.

PubMed

Côté, Isabelle M; Darling, Emily S; Malpica-Cruz, Luis; Smith, Nicola S; Green, Stephanie J; Curtis-Quick, Jocelyn; Layman, Craig

2014-01-01

As a result of being hunted, animals often alter their behaviour in ways that make future encounters with predators less likely. When hunting is carried out for conservation, for example to control invasive species, these behavioural changes can inadvertently impede the success of future efforts. We examined the effects of repeated culling by spearing on the behaviour of invasive predatory lionfish (Pterois volitans/miles) on Bahamian coral reef patches. We compared the extent of concealment and activity levels of lionfish at dawn and midday on 16 coral reef patches off Eleuthera, The Bahamas. Eight of the patches had been subjected to regular daytime removals of lionfish by spearing for two years. We also estimated the distance at which lionfish became alert to slowly approaching divers on culled and unculled reef patches. Lionfish on culled reefs were less active and hid deeper within the reef during the day than lionfish on patches where no culling had occurred. There were no differences at dawn when removals do not take place. Lionfish on culled reefs also adopted an alert posture at a greater distance from divers than lionfish on unculled reefs. More crepuscular activity likely leads to greater encounter rates by lionfish with more native fish species because the abundance of reef fish outside of shelters typically peaks at dawn and dusk. Hiding deeper within the reef could also make remaining lionfish less likely to be encountered and more difficult to catch by spearfishers during culling efforts. Shifts in the behaviour of hunted invasive animals might be common and they have implications both for the impact of invasive species and for the design and success of invasive control programs.

What Doesn't Kill You Makes You Wary? Effect of Repeated Culling on the Behaviour of an Invasive Predator

PubMed Central

Côté, Isabelle M.; Darling, Emily S.; Malpica-Cruz, Luis; Smith, Nicola S.; Green, Stephanie J.; Curtis-Quick, Jocelyn; Layman, Craig

2014-01-01

As a result of being hunted, animals often alter their behaviour in ways that make future encounters with predators less likely. When hunting is carried out for conservation, for example to control invasive species, these behavioural changes can inadvertently impede the success of future efforts. We examined the effects of repeated culling by spearing on the behaviour of invasive predatory lionfish (Pterois volitans/miles) on Bahamian coral reef patches. We compared the extent of concealment and activity levels of lionfish at dawn and midday on 16 coral reef patches off Eleuthera, The Bahamas. Eight of the patches had been subjected to regular daytime removals of lionfish by spearing for two years. We also estimated the distance at which lionfish became alert to slowly approaching divers on culled and unculled reef patches. Lionfish on culled reefs were less active and hid deeper within the reef during the day than lionfish on patches where no culling had occurred. There were no differences at dawn when removals do not take place. Lionfish on culled reefs also adopted an alert posture at a greater distance from divers than lionfish on unculled reefs. More crepuscular activity likely leads to greater encounter rates by lionfish with more native fish species because the abundance of reef fish outside of shelters typically peaks at dawn and dusk. Hiding deeper within the reef could also make remaining lionfish less likely to be encountered and more difficult to catch by spearfishers during culling efforts. Shifts in the behaviour of hunted invasive animals might be common and they have implications both for the impact of invasive species and for the design and success of invasive control programs. PMID:24705447

Does reef architectural complexity influence resource availability for a large reef-dwelling invertebrate?

NASA Astrophysics Data System (ADS)

Lozano-Álvarez, Enrique; Luviano-Aparicio, Nelia; Negrete-Soto, Fernando; Barradas-Ortiz, Cecilia; Aguíñiga-García, Sergio; Morillo-Velarde, Piedad S.; Álvarez-Filip, Lorenzo; Briones-Fourzán, Patricia

2017-10-01

In coral reefs, loss of architectural complexity and its associated habitat degradation is expected to affect reef specialists in particular due to changes in resource availability. We explored whether these features could potentially affect populations of a large invertebrate, the spotted spiny lobster Panulirus guttatus, which is an obligate Caribbean coral reef-dweller with a limited home range. We selected two separate large coral reef patches in Puerto Morelos (Mexico) that differed significantly in structural complexity and level of degradation, as assessed via the rugosity index, habitat assessment score, and percent cover of various benthic components. On each reef, we estimated density of P. guttatus and sampled lobsters to analyze their stomach contents, three different condition indices, and stable isotopes (δ15N and δ13C) in muscle. Lobster density did not vary with reef, suggesting that available crevices in the less complex patch still provided adequate refuge to these lobsters. Lobsters consumed many food types, dominated by mollusks and crustaceans, but proportionally more crustaceans (herbivore crabs) in the less complex patch, which had more calcareous macroalgae and algal turf. Lobsters from both reefs had a similar condition (all three indices) and mean δ15N, suggesting a similar quality of diet between reefs related to their opportunistic feeding, but differed in mean δ13C values, reflecting the different carbon sources between reefs and providing indirect evidence of individuals of P. guttatus foraging exclusively over their home reef. Overall, we found no apparent effects of architectural complexity, at least to the degree observed in our less complex patch, on density, condition, or trophic level of P. guttatus.

Characterization of available light for seagrass and patch reef productivity in Sugarloaf Key, Lower Florida Keys

USGS Publications Warehouse

Toro-Farmer, Gerardo; Muller-Karger, Frank E.; Vega-Rodriguez, Maria; Melo, Nelson; Yates, Kimberly K.; Johns, Elizabeth; Cerdeira-Estrada, Sergio; Herwitz, Stan R.

2016-01-01

Light availability is an important factor driving primary productivity in benthic ecosystems, but in situ and remote sensing measurements of light quality are limited for coral reefs and seagrass beds. We evaluated the productivity responses of a patch reef and a seagrass site in the Lower Florida Keys to ambient light availability and spectral quality. In situ optical properties were characterized utilizing moored and water column bio-optical and hydrographic measurements. Net ecosystem productivity (NEP) was also estimated for these study sites using benthic productivity chambers. Our results show higher spectral light attenuation and absorption, and lower irradiance during low tide in the patch reef, tracking the influx of materials from shallower coastal areas. In contrast, the intrusion of clearer surface Atlantic Ocean water caused lower values of spectral attenuation and absorption, and higher irradiance in the patch reef during high tide. Storms during the studied period, with winds >10 m·s−1, caused higher spectral attenuation values. A spatial gradient of NEP was observed, from high productivity in the shallow seagrass area, to lower productivity in deeper patch reefs. The highest daytime NEP was observed in the seagrass, with values of almost 0.4 g·O2·m−2·h−1. Productivity at the patch reef area was lower in May than during October 2012 (mean = 0.137 and 0.177 g·O2·m−2·h−1, respectively). Higher photosynthetic active radiation (PAR) levels measured above water and lower light attenuation in the red region of the visible spectrum (~666 to ~699 nm) had a positive correlation with NEP. Our results indicate that changes in light availability and quality by suspended or resuspended particles limit benthic productivity in the Florida Keys.

Patch reef modeling: a comparison of Devonian and recent examples

DOE Office of Scientific and Technical Information (OSTI.GOV)

Precht, W.F.

In reef research, models have been developed to define variations in the lithic and biotic development of facies. Walker and Alberstadt, and Hoffman and Narkiewicz developed models for growth of ancient reef communities. Although these models form a solid foundation by which patch reefs can be classed and zoned, they are neither complete nor accurate for all reef types. A comparison was made of Lower Devonian patch reefs from the Appalachian basin of New York, New Jersey, and Pennsylvania, and Holocene examples from the Bahamas and Florida Keys to identify the structure, orientation, community variability, and succession of the reefmore » biofacies. The complexion and genesis of the carbonate lithofacies were also studied. Results show similarities; these include the size, areal distribution, 3-D geometry, wave-resistance potential, lateral sequences of facies, sedimentary textures and structures, vertical zonation explained by growth from low-energy to high-energy regimes, biotic diversity, growth habit and form, and postmortem alteration. Thus, when used in conjunction with the traditional models, the recent can serve as the basis for a general model which include most patch reef types. However, these models should not be used as explicit analogs for all Phanerozoic reefs. Knowing and understanding the limitations of these comparative studies are essential to a fuller comprehension of the potential for variations which exist within and between the traditional models.« less

The importance of spatial fishing behavior for coral reef resilience

NASA Astrophysics Data System (ADS)

Rassweiler, A.; Lauer, M.; Holbrook, S. J.

2016-02-01

Coral reefs are dynamic systems in which disturbances periodically reduce coral cover but are normally followed by recovery of the coral community. However, human activity may have reduced this resilience to disturbance in many coral reef systems, as an increasing number of reefs have undergone persistent transitions from coral-dominated to macroalgal-dominated community states. Fishing on herbivores may be one cause of reduced reef resilience, as lower herbivory can make it easier for macroalgae to become established after a disturbance. Despite the acknowledged importance of fishing, relatively little attention has been paid to the potential for feedbacks between ecosystem state and fisher behavior. Here we couple methods from environmental anthropology and ecology to explore these feedbacks between small-scale fisheries and coral reefs in Moorea, French Polynesia. We document how aspects of ecological state such as the abundance of macroalgae affect people's preference for fishing in particular lagoon habitats. We then incorporate biases towards fishing in certain ecological states into a spatially explicit bio-economic model of ecological dynamics and fishing in Moorea's lagoons. We find that feedbacks between spatial fishing behavior and ecological state can have critical effects on coral reefs. Presence of these spatial behaviors consistently leads to more coherence across the reef-scape. However, whether this coherence manifests as increased resilience or increased fragility depends on the spatial scales of fisher movement and the magnitudes of disturbance. These results emphasize the potential importance of spatially-explicit fishing behavior for reef resilience, but also the complexity of the feedbacks involved.

Atoll-phosphate genesis: Role of lagoonal biomass and possible role of endo-upwelling processes in phosphate concentration

DOE Office of Scientific and Technical Information (OSTI.GOV)

Trichet, J.; Rougerie, F.

1990-06-01

Sedimentological and hydrogeological data in Niau, a closed atoll in French Polynesia where P-concentration has been measured, suggest the role played by lagoonal organic matter in P-accumulation and the possible role of endo-upwelling processes in P-input in the system. A 15 m deep core through the lagoonal deposits shows the succession of organic-rich strata in which the P-content can reach up to 1.3% P{sub 2}O{sub 5}. Such a pattern suggests that, whatever the source of P within the lagoon (lagoonal water, bird guano, or endo-upwelled solutions, see below), this element is likely to be incorporated in quantitatively important lagoonal biomassmore » whose decay releases phosphorus back to the sediment. An example of such biomass and organic matter is given by the large amounts of cyano-bacterial organic matter that are present in the lagoon of Niau. A source for island phosphate has recently been proposed to be relatively deep seawater, which would be endo-upwelled from depths of hundreds of meters ({approximately}500 m, where P content is approximately 1.5 mmol.m{sup {minus}3} PO{sub 4}-P) through the permeable reef-body up to its surface (i.e., to its lagoonal waters, where P content reaches 5 mmol.m{sup {minus}3} in Niau atoll). The energy necessary for the transport of such solutions would be geothermal (at the bottom of the water column, i.e., close to the volcanic substrate of the reef body) and solar at its top through evaporation.« less

Biological community structure on patch reefs in Biscayne National Park, FL, USA

USGS Publications Warehouse

Kuffner, Ilsa B.; Grober-Dunsmore, Rikki; Brock, John C.; Hickey, T. Don

2010-01-01

Coral reef ecosystem management benefits from continual quantitative assessment of the resources being managed, plus assessment of factors that affect distribution patterns of organisms in the ecosystem. In this study, we investigate the relationships among physical, benthic, and fish variables in an effort to help explain the distribution patterns of organisms on patch reefs within Biscayne National Park, FL, USA. We visited a total of 196 randomly selected sampling stations on 12 shallow (<10 m) patch reefs and measured physical variables (e.g., substratum rugosity, substratum type) and benthic and fish community variables. We also incorporated data on substratum rugosity collected remotely via airborne laser surveying (Experimental Advanced Airborne Research Lidar—EAARL). Across all stations, only weak relationships were found between physical, benthic cover, and fish assemblage variables. Much of the variance was attributable to a “reef effect,” meaning that community structure and organism abundances were more variable at stations among reefs than within reefs. However, when the reef effect was accounted for and removed statistically, patterns were detected. Within reefs, juvenile scarids were most abundant at stations with high coverage of the fleshy macroalgae Dictyota spp., and the calcified alga Halimeda tuna was most abundant at stations with low EAARL rugosity. Explanations for the overwhelming importance of “reef” in explaining variance in our dataset could include the stochastic arrangement of organisms on patch reefs related to variable larval recruitment in space and time and/or strong historical effects due to patchy disturbances (e.g., hurricanes, fishing), as well as legacy effects of prior residents (“priority” effects).

Biological Communities and Geomorphology of Patch Reefs in Biscayne National Park, Florida, U.S.A.

USGS Publications Warehouse

Kuffner, Ilsa B.; Brock, John C.; Grober-Dunsmore, Rikki; Hickey, T. Don; Bonito, Victor; Bracone, Jeremy E.; Wright, C. Wayne

2008-01-01

Coral reef ecosystem management benefits from continual, quantitative assessment of the resources being managed, plus assessment of factors that affect distribution patterns of organisms in the ecosystem. In this study, we investigated the relationships among physical, benthic, and fish variables in effort to help explain the distribution patterns of ecologically and economically important species on twelve patch reefs within Biscayne National Park (BNP), Florida, U.S.A. We visited 196 randomly-located sampling stations across twelve shallow (< 10m) patch reefs, using SCUBA to conduct our surveys. We measured physical variables (e.g., substratum type), estimated the percent cover of benthic community members (e.g., coral, algae), and counted and estimated mean size for each fish species observed. We also used high-density bathymetric data collected remotely via airborne laser surveying (Experimental Advanced Airborne Research Lidar (EAARL)) to calculate rugosity (bumpiness) of the reef habitat. Here we present our findings visually by graphing our quantitative community and physical structure data simultaneously in a GIS map format. You will see that biological organisms arrange themselves on each patch reef in a non-random manner. For example, many species of fish prefer to locate themselves in areas of the reef where the rugosity index is high. Rugose parts of the reef provide them with good hiding places from predators. These maps (and the data used to create them) are permanent records of the status of reef resources found on these twelve patch reefs in BNP as of September, 2003. The survey data found in the shapefile located on this CD product includes benthic percent cover data for algae, coral, encrusting invertebrates, and substratum type, in addition to gorgonian abundance and volume, total fish abundance and species richness, and specific counts for Acanthurids (surgeonfish), Scarids (parrotfish), Lutjanids (snappers), Haemulids (grunts), Serranids (groupers), and Pomacentrids (damselfish).

Predicting the Location and Spatial Extent of Submerged Coral Reef Habitat in the Great Barrier Reef World Heritage Area, Australia

PubMed Central

Bridge, Tom; Beaman, Robin; Done, Terry; Webster, Jody

2012-01-01

Aim Coral reef communities occurring in deeper waters have received little research effort compared to their shallow-water counterparts, and even such basic information as their location and extent are currently unknown throughout most of the world. Using the Great Barrier Reef as a case study, habitat suitability modelling is used to predict the distribution of deep-water coral reef communities on the Great Barrier Reef, Australia. We test the effectiveness of a range of geophysical and environmental variables for predicting the location of deep-water coral reef communities on the Great Barrier Reef. Location Great Barrier Reef, Australia. Methods Maximum entropy modelling is used to identify the spatial extent of two broad communities of habitat-forming megabenthos phototrophs and heterotrophs. Models were generated using combinations of geophysical substrate properties derived from multibeam bathymetry and environmental data derived from Bio-ORACLE, combined with georeferenced occurrence records of mesophotic coral communities from autonomous underwater vehicle, remotely operated vehicle and SCUBA surveys. Model results are used to estimate the total amount of mesophotic coral reef habitat on the GBR. Results Our models predict extensive but previously undocumented coral communities occurring both along the continental shelf-edge of the Great Barrier Reef and also on submerged reefs inside the lagoon. Habitat suitability for phototrophs is highest on submerged reefs along the outer-shelf and the deeper flanks of emergent reefs inside the GBR lagoon, while suitability for heterotrophs is highest in the deep waters along the shelf-edge. Models using only geophysical variables consistently outperformed models incorporating environmental data for both phototrophs and heterotrophs. Main Conclusion Extensive submerged coral reef communities that are currently undocumented are likely to occur throughout the Great Barrier Reef. High-quality bathymetry data can be used to identify these reefs, which may play an important role in resilience of the GBR ecosystem to climate change. PMID:23118952

Deposition of organic material in a coral reef lagoon, One Tree Island, Great Barrier Reef

NASA Astrophysics Data System (ADS)

Koop, K.; Larkum, A. W. D.

1987-07-01

Deposition of organic material was measured at four sites on One Tree Island coral reef using fixed sediment traps. Although no reliable data were obtained for the reef crest area because of problems of resuspension, mean deposition in the backreef area amounted to some 4 g organic C m -2 day -1 whereas in the lagoon it was about 1·5 g C m -2 day -1. This amounted to mean nitrogen deposition rates of 160 and 95 mg N m -2 day -1, respectively. As primary production by turf algae, the principal producers at One Tree Island, has been estimated at about 2·3 g C m -2 day -1 for the whole reef system and the weighted mean carbon deposition is estimated at 2·2 g C m -2 day -1, it is clear that the carbon produced by plants is largely retained in the system. Nitrogen deposition, on the other hand, amounted to only about 60% of that produced by turf algae and it must be assumed that much of this leached into the water during sedimentation. Losses of nitrogen may be minimized by incorporation of dissolved nitrogen by pelagic microheterotrophs which may in turn be consumed by filter feeders before they leave the reef.

Miocene reef carbonates of Mariana Islands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siegrist, H.G. Jr.

1988-01-01

Miocene carbonates in the southern Mariana Islands are impressive for their lithologic diversity, thicknesses (over 250 m), and geographic extend (>20% combined outcrop coverage over four major high islands: Guam, Rota, Tinian and Saipan). Sections are dominated either by lagoonal algal-foraminiferal wackestones and mudstones with locally abundant high-energy shelly-skeletal facies, or by rubbly to muddy, fore-reef-to-bank deposits of packstones and grainstones with highly diverse and variable biogenic clasts. Fresh to deeply weathered volcaniclastic material may comprise at least 80% of some high-energy fore-reef facies, whereas lagoonal and bank deposits usually contain less than 0.5% terrigenous material. Surprisingly, the Miocene inmore » the Marianas lacks almost completely any reef-core facies. Several poorly developed coral-rich mounds on Saipan and localized laminated red algal buildups on Guam appear to constitute the extant reef-wall facies in the Miocene. The lack of buildups may be a matter of differential survival; it may result from headland erosion and benching associated with emergency of narrow reef tracts as has been postulated by others for south Guam. Radiometric age dating of these reef carbonates has proven unsuccessful because pervasive diagenesis has transformed the entire Miocene section into low-magnesium calcite with minor and occasional dolomite. Freshwater phreatic diagenesis accounts for the principal porosity variation and trace element distribution.« less

Island-enhanced cooling mechanism in typhoon events revealed by field observations and numerical simulations for a coral reef area, Sekisei Lagoon, Japan

NASA Astrophysics Data System (ADS)

Bernardo, Lawrence Patrick C.; Nadaoka, Kazuo; Nakamura, Takashi; Watanabe, Atsushi

2017-11-01

While widely known for their destructive power, typhoon events can also bring benefit to coral reef ecosystems through typhoon-induced cooling which can mitigate against thermally stressful conditions causing coral bleaching. Sensor deployments in Sekisei Lagoon, Japan's largest coral reef area, during the summer months of 2013, 2014, and 2015 were able to capture local hydrodynamic features of numerous typhoon passages. In particular, typhoons 2015-13 and 2015-15 featured steep drops in near-bottom temperature of 5 °C or more in the north and south sides of Sekisei Lagoon, respectively, indicating local cooling patterns which appeared to depend on the track and intensity of the passing typhoon. This was further investigated using Regional Ocean Modeling System (ROMS) numerical simulations conducted for the summer of 2015. The modeling results showed a cooling trend to the north of the Yaeyama Islands during the passage of typhoon 2015-13, and a cooling trend that moved clockwise from north to south of the islands during the passage of typhoon 2015-15. These local cooling events may have been initiated by the Yaeyama Islands acting as an obstacle to a strong typhoon-generated flow which was modulated and led to prominent cooling of waters on the leeward sides. These lower temperature waters from offshore may then be transported to the shallower inner parts of the lagoon area, which may partly be due to density-driven currents generated by the offshore-inner area temperature difference.

Ecological characteristics of coral patch reefs at Midway Atoll, Northwestern Hawaiian Islands

USGS Publications Warehouse

Schroeder, R.E.; Parrish, J.D.

2006-01-01

Ecological aspects of coral patch reefs were studied from 1981 to 1985 in Welles Harbor, Midway Atoll. Water temperatures varied from 17??C in February to 28??C in August. Sizes of reefs studied were described by mean area (59 m2), mean volume (52 m3), vertical relief (<1 m), and inter-reef isolation (100 m). Considerable temporal change in reef size occurred due to large winter swells shifting bottom sand. Six common species accounted for 70% of all individual fish visually censused over 4 years. Overall fish assemblage composition ranged from 11 to 46 fish/10 m2, from 3 to 14 species. Numerical abundance and species richness for all fish (pooled) strongly correlated with physical reef substrate characteristics of area, volume, and vertical relief during summer. Species diversity (H') was not correlated with the substrate variables, suggesting similarity in the structure of fish communities among different sizes of patch reefs. Daily surveillance for presence of large transient taxa suggested that visits by sharks, large jacks, monk seals, sea turtles, and dolphins were infrequent. Density estimates were made for all conspicuous invertebrate megafauna during initial and final assessments. Six common taxa provided 90% of these counts; nearly half were sea urchins. Percent cover also was recorded for coral and algal species on the patch reefs. Cover by live coral was low (about 7%) and dominated by a few species. Mean algal cover ranged from 32 to 77%. Such information on ecological characteristics of reefs may aid in understanding complex ecological processes and provides an earlier reference for current ecosystem studies.

A review of bottom-up vs. top-down control of sponges on Caribbean fore-reefs: what's old, what's new, and future directions.

PubMed

Pawlik, Joseph R; Loh, Tse-Lynn; McMurray, Steven E

2018-01-01

Interest in the ecology of sponges on coral reefs has grown in recent years with mounting evidence that sponges are becoming dominant members of reef communities, particularly in the Caribbean. New estimates of water column processing by sponge pumping activities combined with discoveries related to carbon and nutrient cycling have led to novel hypotheses about the role of sponges in reef ecosystem function. Among these developments, a debate has emerged about the relative effects of bottom-up (food availability) and top-down (predation) control on the community of sponges on Caribbean fore-reefs. In this review, we evaluate the impact of the latest findings on the debate, as well as provide new insights based on older citations. Recent studies that employed different research methods have demonstrated that dissolved organic carbon (DOC) and detritus are the principal sources of food for a growing list of sponge species, challenging the idea that the relative availability of living picoplankton is the sole proxy for sponge growth or abundance. New reports have confirmed earlier findings that reef macroalgae release labile DOC available for sponge nutrition. Evidence for top-down control of sponge community structure by fish predation is further supported by gut content studies and historical population estimates of hawksbill turtles, which likely had a much greater impact on relative sponge abundances on Caribbean reefs of the past. Implicit to investigations designed to address the bottom-up vs. top-down debate are appropriate studies of Caribbean fore-reef environments, where benthic communities are relatively homogeneous and terrestrial influences and abiotic effects are minimized. One recent study designed to test both aspects of the debate did so using experiments conducted entirely in shallow lagoonal habitats dominated by mangroves and seagrass beds. The top-down results from this study are reinterpreted as supporting past research demonstrating predator preferences for sponge species that are abundant in these lagoonal habitats, but grazed away in fore-reef habitats. We conclude that sponge communities on Caribbean fore-reefs of the past and present are largely structured by predation, and offer new directions for research, such as determining the environmental conditions under which sponges may be food-limited (e.g., deep sea, lagoonal habitats) and monitoring changes in sponge community structure as populations of hawksbill turtles rebound.

A review of bottom-up vs. top-down control of sponges on Caribbean fore-reefs: what’s old, what’s new, and future directions

PubMed Central

2018-01-01

Interest in the ecology of sponges on coral reefs has grown in recent years with mounting evidence that sponges are becoming dominant members of reef communities, particularly in the Caribbean. New estimates of water column processing by sponge pumping activities combined with discoveries related to carbon and nutrient cycling have led to novel hypotheses about the role of sponges in reef ecosystem function. Among these developments, a debate has emerged about the relative effects of bottom-up (food availability) and top-down (predation) control on the community of sponges on Caribbean fore-reefs. In this review, we evaluate the impact of the latest findings on the debate, as well as provide new insights based on older citations. Recent studies that employed different research methods have demonstrated that dissolved organic carbon (DOC) and detritus are the principal sources of food for a growing list of sponge species, challenging the idea that the relative availability of living picoplankton is the sole proxy for sponge growth or abundance. New reports have confirmed earlier findings that reef macroalgae release labile DOC available for sponge nutrition. Evidence for top-down control of sponge community structure by fish predation is further supported by gut content studies and historical population estimates of hawksbill turtles, which likely had a much greater impact on relative sponge abundances on Caribbean reefs of the past. Implicit to investigations designed to address the bottom-up vs. top-down debate are appropriate studies of Caribbean fore-reef environments, where benthic communities are relatively homogeneous and terrestrial influences and abiotic effects are minimized. One recent study designed to test both aspects of the debate did so using experiments conducted entirely in shallow lagoonal habitats dominated by mangroves and seagrass beds. The top-down results from this study are reinterpreted as supporting past research demonstrating predator preferences for sponge species that are abundant in these lagoonal habitats, but grazed away in fore-reef habitats. We conclude that sponge communities on Caribbean fore-reefs of the past and present are largely structured by predation, and offer new directions for research, such as determining the environmental conditions under which sponges may be food-limited (e.g., deep sea, lagoonal habitats) and monitoring changes in sponge community structure as populations of hawksbill turtles rebound. PMID:29404224

An overview of Miocene reefs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jordan, C.F. Jr.; Colgan, M.W.; Frost, S.H.

1990-05-01

Miocene reefs lived approximately within the latitudes of 27{degree}S to 48{degree}N compared with 25{degree}S and 32{degree}N for Holocene reefs. This expansion of reef-growing environments was the result of warm Miocene climates, aided by a eustatic sea level rise and tectonic styles that provided numerous foundations for reef development. The majority of Miocene reefs are found in three main areas: (1) Southeast Asia and the western Pacific, (2) the Mediterranean-Middle East, and (3) Middle America and the Caribbean. These regions, with their distinctive suites of coral and foramineral species, formed three biological provinces; respectively, they are the Indo-Pacific, Tethyan, and Westernmore » Atlantic provinces. Miocene reefs in Southeast Asia occur in several foreland basins as patch reef complexes on paleohighs and as barrier reefs in back-arc basins. Those reefs in the Mediterranean occur as fringing reefs, middle-shelf patch reefs, or as barrier reefs on the edges of tectonic blocks associated with Alpine thrust belts. Most reefs in the Caribbean grew on isolated open-ocean highs of volcanic origin. Miocene reefs display a diversity of framework types: (1) coral-encrusting, red algal boundstones with diverse coral faunas, (2) branching coral-encrusting, red algal boundstones with a limited Poritid fauna, (3) encrusting red algal boundstones. Barrier reef systems are especially rich in encrusting red algae and robust corals; grainstones are common as interbedded sediment. Patch reef complexes, however, display muddy carbonate textures, may have less diverse coral faunas, and commonly have larger foraminifera. The global distribution of Miocene reefs is important because (1) it provides insight into a paleoclimatic view of the earth during a major greenhouse stage and (2) Miocene buildups, such as the Arun (EUR of 14 tcf) and Bima fields (EUR of about 100 MMBO), are exploration targets.« less

Miocene reef carbonates of Mariana Islands

DOE Office of Scientific and Technical Information (OSTI.GOV)

Siegrist, H.G. Jr.

1988-02-01

Miocene carbonates in the southern Mariana Islands are impressive for their lithologic diversity, thicknesses (over 250 m), and geographic extent (> 20% combined outcrop coverage over four major high islands: Guam, Rota, Tinian and Saipan). Sections are dominated either by lagoonal algal-foraminiferal wackestones and mudstones with locally abundant high-energy shelly-skeletal facies, or by rubbly to muddy, fore-reef-to-bank deposits of packstones and grainstones with highly diverse and variable biogenic clasts. Fresh to deeply weathered volcaniclastic material may comprise at least 80% of some high-energy fore-reef facies, whereas lagoonal and bank deposits usually contain less than 0.5% terrigenous material. Surprisingly, the Miocenemore » in the Marianas lacks almost completely any reef-core facies. Several poorly developed coral-rich mounds on Saipan and localized laminated red algal buildups on Guam appear to constitute the extant reef-wall facies in the Miocene. The lack of buildups may be a matter of differential survival; it may result from headland erosion and benching associated with emergence of narrow reef tracts as has been postulated by others for south Guam. Alternatively, the authors are proposing that Miocene bathymetry and the volume of terrigenous influx militated against significant reef core formation. Radiometric age dating of these reef carbonates has proven unsuccessful because pervasive diagenesis has transformed the entire Miocene section into low-magnesium calcite with minor and occasional dolomite. Freshwater phreatic diagenesis accounts for the principal porosity variation and trace element distribution.« less

Atoll-scale patterns in coral reef community structure: Human signatures on Ulithi Atoll, Micronesia.

PubMed

Crane, Nicole L; Nelson, Peter; Abelson, Avigdor; Precoda, Kristin; Rulmal, John; Bernardi, Giacomo; Paddack, Michelle

2017-01-01

The dynamic relationship between reefs and the people who utilize them at a subsistence level is poorly understood. This paper characterizes atoll-scale patterns in shallow coral reef habitat and fish community structure, and correlates these with environmental characteristics and anthropogenic factors, critical to conservation efforts for the reefs and the people who depend on them. Hierarchical clustering analyses by site for benthic composition and fish community resulted in the same 3 major clusters: cluster 1-oceanic (close proximity to deep water) and uninhabited (low human impact); cluster 2-oceanic and inhabited (high human impact); and cluster 3-lagoonal (facing the inside of the lagoon) and inhabited (highest human impact). Distance from village, reef exposure to deep water and human population size had the greatest effect in predicting the fish and benthic community structure. Our study demonstrates a strong association between benthic and fish community structure and human use across the Ulithi Atoll (Yap State, Federated States of Micronesia) and confirms a pattern observed by local people that an 'opportunistic' scleractinian coral (Montipora sp.) is associated with more highly impacted reefs. Our findings suggest that small human populations (subsistence fishing) can nevertheless have considerable ecological impacts on reefs due, in part, to changes in fishing practices rather than overfishing per se, as well as larger global trends. Findings from this work can assist in building local capacity to manage reef resources across an atoll-wide scale, and illustrates the importance of anthropogenic impact even in small communities.

Characterization and sources of colored dissolved organic matter in a coral reef ecosystem subject to ultramafic erosion pressure (New Caledonia, Southwest Pacific).

PubMed

Martias, Chloé; Tedetti, Marc; Lantoine, François; Jamet, Léocadie; Dupouy, Cécile

2018-03-01

The eastern lagoon of New Caledonia (NC, Southwest Pacific), listed as a UNESCO World Heritage site, hosts the world's second longest double-barrier coral reef. This lagoon receives river inputs, oceanic water arrivals, and erosion pressure from ultramafic rocks, enriched in nickel (Ni) and cobalt (Co). The aim of this study was to characterize colored dissolved organic matter (CDOM), as well as to determine its main sources and its possible relationships (through the use of Pearson correlation coefficients, r) with biogeochemical parameters, plankton communities and trace metals in the NC eastern lagoon. Water samples were collected in March 2016 along a series of river/lagoon/open-ocean transects. The absorption coefficient at 350nm (a 350 ) revealed the influence of river inputs on the CDOM distribution. The high values of spectral slope (S 275-295 , >0.03m -1 ) and the low values of specific ultraviolet absorbance (SUVA 254 , <4Lmg-C -1 m -1 ) highlighted the photodegradation of CDOM in surface waters. The application of parallel factor analysis (PARAFAC) on excitation-emission matrices (EEMs) allowed the identification of four CDOM components: (1) one humic- and one tyrosine-like fluorophores. They had terrestrial origin, exported through rivers and undergoing photo- and bio-degradation in the lagoon. These two fluorophores were linked to manganese (Mn) in southern rivers (r=0.46-0.50, n=21, p<0.05). (2) A tryptophan-like fluorophore, which exhibited higher levels offshore. It would be potentially released from the coral reef. (3) A second tyrosine-like ("tyrosine 2-like") fluorophore. Linked to Prochlorococcus cyanobacteria (r=0.39, n=47, p<0.05), this fluorophore would have an oceanic origin and enter in the lagoon through its southern and northern extremities. It also displayed relationships with Ni and Co content (r=0.53-0.54, n=21, p<0.05). This work underlines the diversity of CDOM sources in the NC eastern lagoon. Copyright © 2017 Elsevier B.V. All rights reserved.

PAHs in the Great Barrier Reef Lagoon reach potentially toxic levels from coal port activities

NASA Astrophysics Data System (ADS)

Burns, Kathryn A.

2014-05-01

In view of the controversy over expanding the coastal coal ports bordering the Great Barrier Reef (GBR) Lagoon and the World Heritage Area, I re-evaluated the data published in Burns and Brinkman (2011). I used the US EPA procedures for the determination of Equilibrium Partitioning Sediment Benchmarks (ESBs) for the protection of benthic organisms (Hansen et al., 2003), and the new proposed ANZECC/ARMCANZ (2013) sediment quality guidelines (Simpson et al., 2013) and determined that the coastal sediments offshore from the Hay Point coal terminal and suspended sediments caught in sediment traps inshore and at the offshore coral reefs contained levels of PAHs that approach the estimates for toxicity to benthic and water column organisms. This result is discussed in relation to risks posed to the GBR ecosystem by the port practices and the imminent expansion of the Abbott Point, Hay Point and other coal terminals.

Ecology of the ciguatera causing dinoflagellates from the Northern Great Barrier Reef: changes in community distribution and coastal eutrophication.

PubMed

Skinner, Mark P; Lewis, Richard J; Morton, Steve

2013-12-15

Ciguatera fish poisoning (CFP) is known to be caused by the ciguatoxins from the dinoflagellate genus Gambierdiscus, however, there is the potential for other toxins such as okadaic acid and dinophysistoxins from the genus Prorocentrum, and palytoxin from the genus Ostreopsis, to contaminate seafood. These genera may also be indicators of ecosystem health and potentially impact on coral reef ecosystems and the role they may play in the succession of coral to macroalgae dominated reefs has not been researched. Sixteen GBR field sites spanning inshore, mid-lagoon and outer lagoon (offshore) regions were studied. Samples were collected from September 2006 to December 2007 and abundance of benthic dinoflagellates on different host macroalgae and concentration of nutrients present in the water column were determined. The maximum abundance of Prorocentrum, Ostreopsis and Gambierdiscus found was 112, 793 and 50 cells per gram wet weight of host macroalgae, respectively. The average level of Dissolved Inorganic Nitrogen (DIN) in the water column across all sites (0.03 mg/L) was found to be more than double the threshold critical value (0.013 mg/L) for healthy coral reefs. Compared to a previous study 1984, there is evidence of a major shift in the distribution and abundance of these dinoflagellates. Inshore reefs have either of Prorocentrum (as at Green Island) or Ostreopsis (as at Magnetic Island) dominating the macroalgal surface niche which was once dominated by Gambierdiscus, whilst at offshore regions Gambierdiscus is still dominant. This succession may be linked to the ongoing eutrophication of the GBR lagoon and have consequences for the sources of toxins for ongoing cases of ciguatera. Published by Elsevier Ltd.

Influence of ambient water intrusion on coral reef acidification in the Chuuk lagoon, located in the coral-rich western Pacific Ocean

NASA Astrophysics Data System (ADS)

Ko, Young Ho; Lee, Kitack; Noh, Jae Hoon; Lee, Charity M.; Kleypas, Joan A.; Jeong, Hae Jin; Kim, Kwang Young

2016-04-01

Weekly carbonate chemistry condition data recorded between 2008 and 2014 in the Chuuk lagoon (7.3°N and 151.5°E) of the Federated States of Micronesia, located in the western Pacific Ocean, were analyzed. The results showed that, during periods of weak intrusion of ambient seawater from the surrounding open ocean, two internal biological processes (calcification and respiration) reinforced each other and together lowered the pH of the reef water for extended periods, ranging from a few to several months. The analysis indicated that reduced intrusion of ambient water is associated with periods of low wind speeds. Such conditions increase the residence time of reef water, thus promoting acidification by respiration and calcification. This phenomenon likely affects many other areas of the coral-rich western Pacific Ocean, which contains 50% of global coral reefs and in which the degree of ambient water intrusion into the atolls has been shown to be closely associated with the El Niño-Southern Oscillation-induced wind speed change.

Preliminary numerical simulation for shallow strata stability of coral reef in South China Sea

NASA Astrophysics Data System (ADS)

Tang, Qinqin; Zhan, Wenhuan; Zhang, Jinchang

2017-04-01

Coral reefs are the geologic material and special rock and soil, which live in shallow water of the tropic ocean and are formed through biological and geological action. Since infrastructure construction is being increasingly developed on coral reefs during recent years, it is necessary to evaluate the shallow strata stability of coral reefs in the South China Sea. The paper is to study the borehole profiles for shallow strata of coral reefs in the South China Sea, especially in the hydrodynamic marine environment?, and to establish a geological model for numerical simulation with Geo-Studio software. Five drilling holes show a six-layer shallow structure of South China Sea, including filling layer, mid-coarse sand, coral sand gravel, fine sand, limestone debris and reef limestone. The shallow coral reef profile next to lagoon is similar to "layers cake", in which the right side close to the sea is analogous to "block cake". The simulation results show that coral reef stability depends on wave loads and earthquake strength, as well as the physical properties of coral reefs themselves. The safety factor of the outer reef is greater than 10.0 in the static condition, indicating that outer reefs are less affected by the wave and earthquake. However, the safety factor next to lagoon is ranging from 0.1 to 4.9. The main reason for the variations that the strata of coral reefs close to the sea are thick. For example, the thickness of reef limestone is more than 10 m and equivalent to the block. When the thickness of inside strata is less than 10 m, they show weak engineering geological characteristics. These findings can provide useful information for coral reef constructions in future. This work was funded by National Basic Research Program of China (contract: 2013CB956104) and National Natural Science Foundation of China (contract: 41376063).

Decline in sea snake abundance on a protected coral reef system in the New Caledonian Lagoon

NASA Astrophysics Data System (ADS)

Goiran, C.; Shine, R.

2013-03-01

Monitoring results from a small reef (Ile aux Canards) near Noumea in the New Caledonian Lagoon reveal that numbers of turtle-headed sea snakes ( Emydocephalus annulatus) have been in consistent decline over a 9-year period, with average daily counts of snakes decreasing from >6 to <2 over this period. Causal factors for the decline are unclear, because the site is a protected area used only for tourism. Our results suggest that wildlife management authorities should carefully monitor sea snake populations to check whether the declines now documented for New Caledonia and in nearby Australian waters also occur around the islands of the Indo-Pacific.

Holocene Core Logs and Site Statistics for Modern Patch-Reef Cores: Biscayne National Park, Florida

USGS Publications Warehouse

Reich, Christopher D.; Hickey, T. Don; DeLong, Kristine L.; Poore, Richard Z.; Brock, John C.

2009-01-01

The bedrock in Biscayne National Park (BNP), a 1,730-square kilometer (km2) region off southeast Florida, consists of Pleistocene (1.8 million years ago (Ma) to 10,000 years ago (ka)) and Holocene (10 ka to present) carbonate rocks (Enos and Perkins, 1977; Halley and others, 1997; Multer and others, 2002). Most of the surficial limestone in BNP, including the islands of the Florida Keys, was formed at ~125 ka during the highstand of marine oxygen-isotope substage 5e, when sea level was approximately 6 meters (m) higher than today (Chappell and Shackleton, 1986; Multer and others, 2002; Lidz and others, 2003; Siddall and others, 2003; Balsillie and Donoghue, 2004). During the substage-5e regression, the entire Florida Platform became exposed. Subaerial exposure lasted for approximately 115,000 years (kyr), which resulted in erosion and enhancement of karst-like features (Lidz and others, 2006). As the Holocene transgression began to flood the Florida shelf ~7 to 6 ka, the bedrock depression under Biscayne Bay began to flood, and Holocene coral and reef debris laid the foundation for the present reef system (Enos and Perkins, 1977; Lighty and others, 1982; Toscano and Macintyre, 2003; Lidz and others, 2006). More than 3,000 patch reefs exist within the BNP boundary. Most contain hermatypic corals of various species such as those belonging to Montastrea, Diploria, Siderastrea, Porites, Acropora, and Agaricia. Patch reefs within BNP have two morphologies: pinnacle and flat top. Experimental Advanced Airborne Research Lidar (EAARL) data collected along the offshore BNP coral reef tract show that these two morphologies are clearly defined both in the high-resolution bathymetry maps produced by the Lidar data and by statistical analyses of the Lidar dataset (Brock and others, 2008). Brock and others (2008) also show that the pinnacle patch reefs are deeper than the more shallow, broad, and flat patch reefs. The control for these two patch-reef morphologies is unclear; however, their shapes may be due to a slightly lowered sea level or a stillstand in the middle-Holocene around 4 ka that caused erosion of the shallower reefs and allowed the deeper reefs to remain unaffected. Lidz and others (2006) have suggested a stillstand around 4 ka that carved a 2.5-kilometer (km)-wide nearshore rock ledge into the seaward side of every island in the Florida Keys. The objectives of this study were to sample living corals to understand the more recent (<200 years) changes in climate and environmental conditions of the area and to investigate the Holocene (in this case, <8,000 years in the Florida Keys) depositional history at progressively deeper patch-reef sites. This report provides statistics for the cores and core sites and a basic lithologic description of these Holocene cores.

LIDAR optical rugosity of coral reefs in Biscayne National Park, Florida

USGS Publications Warehouse

Brock, J.C.; Wright, C.W.; Clayton, T.D.; Nayegandhi, A.

2004-01-01

The NASA Experimental Advanced Airborne Research Lidar (EAARL), a temporal waveform-resolving, airborne, green wavelength LIDAR (light detection and ranging), is designed to measure the submeter-scale topography of shallow reef substrates. Topographic variability is a prime component of habitat complexity, an ecological factor that both expresses and controls the abundance and distribution of many reef organisms. Following the acquisition of EAARL coverage over both mid-platform patch reefs and shelf-margin bank reefs within Biscayne National Park in August 2002, EAARL-based optical indices of topographic variability were evaluated at 15 patch reef and bank reef sites. Several sites were selected to match reefs previously evaluated in situ along underwater video and belt transects. The analysis used large populations of submarine topographic transects derived from the examination of closely spaced laser spot reflections along LIDAR raster scans. At all 15 sites, each LIDAR transect was evaluated separately to determine optical rugosity (Rotran), and the average elevation difference between adjacent points (Av(??E ap)). Further, the whole-site mean and maximum values of Ro tran and Av(??Eap) for the entire population of transects at each analysis site, along with their standard deviations, were calculated. This study revealed that the greater habitat complexity of inshore patch reefs versus outer bank reefs results in relative differences in topographic complexity that can be discerned in the laser returns. Accordingly, LIDAR sensing of optical rugosity is proposed as a complementary new technique for the rapid assessment of shallow coral reefs. ?? Springer-Verlag 2004.

Carbon and nitrogen cycling in the Zhubi coral reef lagoon of the South China Sea as revealed by 210Po and 210Pb.

PubMed

Yang, W F; Huang, Y P; Chen, M; Qiu, Y S; Li, H B; Zhang, L

2011-05-01

The radionuclides (210)Po and (210)Pb were examined to trace the cycling of particulate organic carbon (POC) and particulate organic nitrogen (PON) in the Zhubi coral reef lagoon. The net export flux of POC to the open sea is 14 mg Cm(-2) d(-1). However, the net exchange of PON has not yet been observed. On average, the vertical export fluxes in the lagoon of POC and PON, as derived from (210)Po/(210)Pb disequilibria, are 43 mg Cm(-2) d(-1) and 13.8 mg Nm(-2) d(-1), respectively. The deficit of (210)Po relative to (210)Pb in particulate matter provides evidence for the degradation of particulate organic matter. According to the mass balance budgets, 310 mg Cm(-2) d(-1) and 121 mg Nm(-2) d(-1) were recycled into dissolved fractions. Based on a first-order kinetics model, the degradation rate constants of POC and PON are 0.28 and 0.30 m(-1), respectively. Thus, (210)Po and (210)Pb can quantify the cycling of carbon and nitrogen in this coral lagoon. Copyright © 2011 Elsevier Ltd. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cuffey, R.J.; Pachut, J.F.

The Holocene reef-building coral Favia pallida was sampled at 4.5 m depth increments (to 40 m) from two reefs on Enewetak Atoll to examine intraspecific environmental effects. An exposed outer reef was massive and wall-like, whereas a sheltered lagoonal reef grew as a slender pinnacle. Corallite diameter and growth rate, two attributes retrievable in fossil corals, were measured with data partitioned into shallow (<20 m), intermediate (20 to 29 m), and deep-water (>29 m) subsets. Highly significant differences between depth zone populations were found for both corallite diameters and growth rates in analyses of individual and combined reef data sets.more » Canonical variates analyses (CVA) separated populations from depth zones along single, highly significant, functions. Centroids and 95% confidence intervals, calculated from CVA scores of colonies in each population, are widely separated for the lagoon reef and combined data sets. Conversely, populations from shallow and intermediate depths on the outer reef display overlapping confidence bars indicative of more gradational morphologic changes. When CV's were used to classify specimens to groups, misassignments of intermediate depth specimens to shallow or deep-water populations underscored the gradational nature of the environment. Completely intergrading populations of Favia pallida collected from different depths can be morphologically separated into statistically distinct groupings. A stratigraphic succession of such morphotypes might be interpreted as abruptly appearing separate species if sampling were not as uniform, systematic, and detailed as was possible on modern reefs. Analyses of evolutionary patterns must carefully assess potential effects of clinal variation if past evolutionary patterns are to be interpreted correctly.« less

Atoll-scale patterns in coral reef community structure: Human signatures on Ulithi Atoll, Micronesia

PubMed Central

Nelson, Peter; Abelson, Avigdor; Precoda, Kristin; Rulmal, John; Bernardi, Giacomo; Paddack, Michelle

2017-01-01

The dynamic relationship between reefs and the people who utilize them at a subsistence level is poorly understood. This paper characterizes atoll-scale patterns in shallow coral reef habitat and fish community structure, and correlates these with environmental characteristics and anthropogenic factors, critical to conservation efforts for the reefs and the people who depend on them. Hierarchical clustering analyses by site for benthic composition and fish community resulted in the same 3 major clusters: cluster 1–oceanic (close proximity to deep water) and uninhabited (low human impact); cluster 2–oceanic and inhabited (high human impact); and cluster 3–lagoonal (facing the inside of the lagoon) and inhabited (highest human impact). Distance from village, reef exposure to deep water and human population size had the greatest effect in predicting the fish and benthic community structure. Our study demonstrates a strong association between benthic and fish community structure and human use across the Ulithi Atoll (Yap State, Federated States of Micronesia) and confirms a pattern observed by local people that an ‘opportunistic’ scleractinian coral (Montipora sp.) is associated with more highly impacted reefs. Our findings suggest that small human populations (subsistence fishing) can nevertheless have considerable ecological impacts on reefs due, in part, to changes in fishing practices rather than overfishing per se, as well as larger global trends. Findings from this work can assist in building local capacity to manage reef resources across an atoll-wide scale, and illustrates the importance of anthropogenic impact even in small communities. PMID:28489903

Earth Observations taken by the Expedition 20 crew

NASA Image and Video Library

2009-07-01

ISS020-E-016279 (1 July 2009) --- Millennium Island is featured in this image photographed by an Expedition 20 crew member on the International Space Station. Millennium Island ? known as Caroline Island prior to 2000 ? is located at the southern end of the Line Islands in the South Pacific Ocean. This uninhabited island is part of the Republic of Kiribati, an island nation comprised of 32 atolls (including Millennium Island) and one raised coral island. Millennium Island is formed from a number of smaller islets built on coral reefs. The coral reefs grew around a now-submerged volcanic peak, leaving a ring of coral around an inner lagoon. The islands above the waterline are composed primarily of limestone rock and sand derived from the reefs. At a maximum height of approximately 6 m above sea level, Millennium Island has been identified as being at great risk from sea level rise by the United Nations. The islets of Millennium Island are readily visible in this photograph as irregular green vegetated areas surrounding the inner lagoon. The shallow lagoon waters are a lighter blue than the deeper surrounding ocean water; tan linear ?fingers? within the lagoon are the tops of corals. The two largest islets are Nake Islet and South Islet, located at the north and south ends of Millennium Island respectively. The ecosystem of Millennium Island is considered to be relatively pristine despite periods of human habitation, guano mining, and agricultural activities, and the island has been recommended as both a World Heritage site and Biosphere Reserve.

Baseline Assessment of Net Calcium Carbonate Accretion Rates on U.S. Pacific Reefs.

PubMed

Vargas-Ángel, Bernardo; Richards, Cristi L; Vroom, Peter S; Price, Nichole N; Schils, Tom; Young, Charles W; Smith, Jennifer; Johnson, Maggie D; Brainard, Russell E

2015-01-01

This paper presents a comprehensive quantitative baseline assessment of in situ net calcium carbonate accretion rates (g CaCO3 cm(-2) yr(-1)) of early successional recruitment communities on Calcification Accretion Unit (CAU) plates deployed on coral reefs at 78 discrete sites, across 11 islands in the central and south Pacific Oceans. Accretion rates varied substantially within and between islands, reef zones, levels of wave exposure, and island geomorphology. For forereef sites, mean accretion rates were the highest at Rose Atoll, Jarvis, and Swains Islands, and the lowest at Johnston Atoll and Tutuila. A comparison between reef zones showed higher accretion rates on forereefs compared to lagoon sites; mean accretion rates were also higher on windward than leeward sites but only for a subset of islands. High levels of spatial variability in net carbonate accretion rates reported herein draw attention to the heterogeneity of the community assemblages. Percent cover of key early successional taxa on CAU plates did not reflect that of the mature communities present on surrounding benthos, possibly due to the short deployment period (2 years) of the experimental units. Yet, net CaCO3 accretion rates were positively correlated with crustose coralline algae (CCA) percent cover on the surrounding benthos and on the CAU plates, which on average represented >70% of the accreted material. For foreeefs and lagoon sites combined CaCO3 accretion rates were statistically correlated with total alkalinity and Chlorophyll-a; a GAM analysis indicated that SiOH and Halimeda were the best predictor variables of accretion rates on lagoon sites, and total alkalinity and Chlorophyll-a for forereef sites, demonstrating the utility of CAUs as a tool to monitor changes in reef accretion rates as they relate to ocean acidification. This study underscores the pivotal role CCA play as a key benthic component and supporting actively calcifying reefs; high Mg-calcite exoskeletons makes CCA extremely susceptible changes in ocean water pH, emphasizing the far-reaching threat that ocean acidification poses to the ecological function and persistence of coral reefs worldwide.

Baseline Assessment of Net Calcium Carbonate Accretion Rates on U.S. Pacific Reefs

PubMed Central

Vargas-Ángel, Bernardo; Richards, Cristi L.; Vroom, Peter S.; Price, Nichole N.; Schils, Tom; Young, Charles W.; Smith, Jennifer; Johnson, Maggie D.; Brainard, Russell E.

2015-01-01

This paper presents a comprehensive quantitative baseline assessment of in situ net calcium carbonate accretion rates (g CaCO3 cm-2 yr-1) of early successional recruitment communities on Calcification Accretion Unit (CAU) plates deployed on coral reefs at 78 discrete sites, across 11 islands in the central and south Pacific Oceans. Accretion rates varied substantially within and between islands, reef zones, levels of wave exposure, and island geomorphology. For forereef sites, mean accretion rates were the highest at Rose Atoll, Jarvis, and Swains Islands, and the lowest at Johnston Atoll and Tutuila. A comparison between reef zones showed higher accretion rates on forereefs compared to lagoon sites; mean accretion rates were also higher on windward than leeward sites but only for a subset of islands. High levels of spatial variability in net carbonate accretion rates reported herein draw attention to the heterogeneity of the community assemblages. Percent cover of key early successional taxa on CAU plates did not reflect that of the mature communities present on surrounding benthos, possibly due to the short deployment period (2 years) of the experimental units. Yet, net CaCO3 accretion rates were positively correlated with crustose coralline algae (CCA) percent cover on the surrounding benthos and on the CAU plates, which on average represented >70% of the accreted material. For foreeefs and lagoon sites combined CaCO3 accretion rates were statistically correlated with total alkalinity and Chlorophyll-a; a GAM analysis indicated that SiOH and Halimeda were the best predictor variables of accretion rates on lagoon sites, and total alkalinity and Chlorophyll-a for forereef sites, demonstrating the utility of CAUs as a tool to monitor changes in reef accretion rates as they relate to ocean acidification. This study underscores the pivotal role CCA play as a key benthic component and supporting actively calcifying reefs; high Mg-calcite exoskeletons makes CCA extremely susceptible changes in ocean water pH, emphasizing the far-reaching threat that ocean acidification poses to the ecological function and persistence of coral reefs worldwide. PMID:26641885

Postglacial Fringing-Reef to Barrier-Reef conversion on Tahiti links Darwin's reef types

NASA Astrophysics Data System (ADS)

Blanchon, Paul; Granados-Corea, Marian; Abbey, Elizabeth; Braga, Juan C.; Braithwaite, Colin; Kennedy, David M.; Spencer, Tom; Webster, Jody M.; Woodroffe, Colin D.

2014-05-01

In 1842 Charles Darwin claimed that vertical growth on a subsiding foundation caused fringing reefs to transform into barrier reefs then atolls. Yet historically no transition between reef types has been discovered and they are widely considered to develop independently from antecedent foundations during glacio-eustatic sea-level rise. Here we reconstruct reef development from cores recovered by IODP Expedition 310 to Tahiti, and show that a fringing reef retreated upslope during postglacial sea-level rise and transformed into a barrier reef when it encountered a Pleistocene reef-flat platform. The reef became stranded on the platform edge, creating a lagoon that isolated it from coastal sediment and facilitated a switch to a faster-growing coral assemblage dominated by acroporids. The switch increased the reef's accretion rate, allowing it to keep pace with rising sea level, and transform into a barrier reef. This retreat mechanism not only links Darwin's reef types, but explains the re-occupation of reefs during Pleistocene glacio-eustacy.

Spatial and temporal variation in reef-scale carbonate storage of large benthic foraminifera: a case study on One Tree Reef

NASA Astrophysics Data System (ADS)

Doo, Steve S.; Hamylton, Sarah; Finfer, Joshua; Byrne, Maria

2017-03-01

Large benthic foraminifera (LBFs) are a vital component of coral reef carbonate production, often overlooked due to their small size. These super-abundant calcifiers are crucial to reef calcification by generation of lagoon and beach sands. Reef-scale carbonate production by LBFs is not well understood, and seasonal fluctuations in this important process are largely unquantified. The biomass of five LBF species in their algal flat habitat was quantified in the austral winter (July 2013), spring (October 2013), and summer (February 2014) at One Tree Reef. WorldView-2 satellite images were used to characterize and create LBF habitat maps based on ground-referenced photographs of algal cover. Habitat maps and LBF biomass measurements were combined to estimate carbonate storage across the entire reef flat. Total carbonate storage of LBFs on the reef flat ranged from 270 tonnes (winter) to 380 tonnes (summer). Satellite images indicate that the habitat area used by LBFs ranged from 0.6 (winter) to 0.71 km2 (spring) of a total possible area of 0.96 km2. LBF biomass was highest in the winter when algal habitat area was lowest, but total carbonate storage was the highest in the summer, when algal habitat area was intermediate. Our data suggest that biomass measurements alone do not capture total abundance of LBF populations (carbonate storage), as the area of available habitat is variable. These results suggest LBF carbonate production studies that measure biomass in discrete locations and single time points fail to capture accurate reef-scale production by not incorporating estimates of the associated algal habitat. Reef-scale measurements in this study can be incorporated into carbonate production models to determine the role of LBFs in sedimentary landforms (lagoons, beaches, etc.). Based on previous models of entire reef metabolism, our estimates indicate that LBFs contribute approximately 3.9-5.4% of reef carbonate budgets, a previously underappreciated carbon sink.

Physical and Biological Controls on the Carbonate Chemistry of Coral Reef Waters: Effects of Metabolism, Wave Forcing, Sea Level, and Geomorphology

PubMed Central

Falter, James L.; Lowe, Ryan J.; Zhang, Zhenlin; McCulloch, Malcolm

2013-01-01

We present a three-dimensional hydrodynamic-biogeochemical model of a wave-driven coral-reef lagoon system using the circulation model ROMS (Regional Ocean Modeling System) coupled with the wave transformation model SWAN (Simulating WAves Nearshore). Simulations were used to explore the sensitivity of water column carbonate chemistry across the reef system to variations in benthic reef metabolism, wave forcing, sea level, and system geomorphology. Our results show that changes in reef-water carbonate chemistry depend primarily on the ratio of benthic metabolism to the square root of the onshore wave energy flux as well as on the length and depth of the reef flat; however, they are only weakly dependent on channel geometry and the total frictional resistance of the reef system. Diurnal variations in pCO2, pH, and aragonite saturation state (Ωar) are primarily dependent on changes in net production and are relatively insensitive to changes in net calcification; however, net changes in pCO2, pH, and Ωar are more strongly influenced by net calcification when averaged over 24 hours. We also demonstrate that a relatively simple one-dimensional analytical model can provide a good description of the functional dependence of reef-water carbonate chemistry on benthic metabolism, wave forcing, sea level, reef flat morphology, and total system frictional resistance. Importantly, our results indicate that any long-term (weeks to months) net offsets in reef-water pCO2 relative to offshore values should be modest for reef systems with narrow and/or deep lagoons. Thus, the long-term evolution of water column pCO2 in many reef environments remains intimately connected to the regional-scale oceanography of offshore waters and hence directly influenced by rapid anthropogenically driven increases in pCO2. PMID:23326411

Physical and biological controls on the carbonate chemistry of coral reef waters: effects of metabolism, wave forcing, sea level, and geomorphology.

PubMed

Falter, James L; Lowe, Ryan J; Zhang, Zhenlin; McCulloch, Malcolm

2013-01-01

We present a three-dimensional hydrodynamic-biogeochemical model of a wave-driven coral-reef lagoon system using the circulation model ROMS (Regional Ocean Modeling System) coupled with the wave transformation model SWAN (Simulating WAves Nearshore). Simulations were used to explore the sensitivity of water column carbonate chemistry across the reef system to variations in benthic reef metabolism, wave forcing, sea level, and system geomorphology. Our results show that changes in reef-water carbonate chemistry depend primarily on the ratio of benthic metabolism to the square root of the onshore wave energy flux as well as on the length and depth of the reef flat; however, they are only weakly dependent on channel geometry and the total frictional resistance of the reef system. Diurnal variations in pCO(2), pH, and aragonite saturation state (Ω(ar)) are primarily dependent on changes in net production and are relatively insensitive to changes in net calcification; however, net changes in pCO(2), pH, and Ω(ar) are more strongly influenced by net calcification when averaged over 24 hours. We also demonstrate that a relatively simple one-dimensional analytical model can provide a good description of the functional dependence of reef-water carbonate chemistry on benthic metabolism, wave forcing, sea level, reef flat morphology, and total system frictional resistance. Importantly, our results indicate that any long-term (weeks to months) net offsets in reef-water pCO(2) relative to offshore values should be modest for reef systems with narrow and/or deep lagoons. Thus, the long-term evolution of water column pCO(2) in many reef environments remains intimately connected to the regional-scale oceanography of offshore waters and hence directly influenced by rapid anthropogenically driven increases in pCO(2).

Late Miocene Coral faunas of Iran (Zagros, Aghar, Firuz abad, Fars) palaeoecology and palaeobiogeography

NASA Astrophysics Data System (ADS)

Dehbozorgi, M.; Yazdi, M.; Torabi, H.

2009-04-01

Late Miocene Corals assemblage from Zagros Iran are investigated with respect to their palaeoecology and palaeobiogeography implications. This Corals are compared with fauna from Mediterranean Tethys and the Indopacific. Small foraminifers are used for biogeography and to support paleoecology interpretation. The studied section situated in the Zagros Mishan F.m is last depositions sea. A distinct horizon characterized by Porites- Antiguastrea assemblage associated Milliolid and Rotalia is interpreted a shallow bioclastic shoal. Patch reef with a porites and faviidae assemblage are a common feature of Oligocene and Miocene coral occurrence and indicate water depth of less than 20m. The diversity of corals in this area are low and all corals are hematypic. Miocene Corals from Mishan F.m Comprise 7 genera and occur in the single horizon or patch reef. This Corals and patch reefs are compared with corals and patch reefs in Qom F.m Central Iran. This corals report from this section: Antiguastrea sp., Monastrea sp., Favites sp., Porites sp., Dichocoenia sp., Asterohelia sp., Leptoria sp. Keywords: Miocene- Iran- Mishan-Zagros- Formation- Tethys seaway- Corals- Palaeoecology- palaeobiogeography.

Great Barrier Reef, Queensland, Australia

NASA Technical Reports Server (NTRS)

1990-01-01

This detailed view of the Great Barrier Reef, Queensland, Australia (19.5S, 149.5E) shows several small patch reefs within the overall reef system. The Great Barrier Reef, largest in the world, comprises thousands of individual reefs of great variety and are closely monitored by marine ecologists. These reefs are about 6000 years old and sit on top of much older reefs. The most rapid coral growth occurs on the landward side of the reefs.

Testing new approaches to carbonate system simulation at the reef scale: the ReefSam model first results, application to a question in reef morphology and future challenges.

NASA Astrophysics Data System (ADS)

Barrett, Samuel; Webster, Jody

2016-04-01

Numerical simulation of the stratigraphy and sedimentology of carbonate systems (carbonate forward stratigraphic modelling - CFSM) provides significant insight into the understanding of both the physical nature of these systems and the processes which control their development. It also provides the opportunity to quantitatively test conceptual models concerning stratigraphy, sedimentology or geomorphology, and allows us to extend our knowledge either spatially (e.g. between bore holes) or temporally (forwards or backwards in time). The later is especially important in determining the likely future development of carbonate systems, particularly regarding the effects of climate change. This application, by its nature, requires successful simulation of carbonate systems on short time scales and at high spatial resolutions. Previous modelling attempts have typically focused on the scales of kilometers and kilo-years or greater (the scale of entire carbonate platforms), rather than at the scale of centuries or decades, and tens to hundreds of meters (the scale of individual reefs). Previous work has identified limitations in common approaches to simulating important reef processes. We present a new CFSM, Reef Sedimentary Accretion Model (ReefSAM), which is designed to test new approaches to simulating reef-scale processes, with the aim of being able to better simulate the past and future development of coral reefs. Four major features have been tested: 1. A simulation of wave based hydrodynamic energy with multiple simultaneous directions and intensities including wave refraction, interaction, and lateral sheltering. 2. Sediment transport simulated as sediment being moved from cell to cell in an iterative fashion until complete deposition. 3. A coral growth model including consideration of local wave energy and composition of the basement substrate (as well as depth). 4. A highly quantitative model testing approach where dozens of output parameters describing the reef morphology and development are compared with observational data. Despite being a test-bed and work in progress, ReefSAM was able to simulate the Holocene development of One Tree Reef in the Southern Great Barrier Reef (Australia) and was able to improve upon previous modelling attempts in terms of both quantitative measures and qualitative outputs, such as the presence of previously un-simulated reef features. Given the success of the model in simulating the Holocene development of OTR, we used it to quantitatively explore the effect of basement substrate depth and morphology on reef maturity/lagoonal filling (as discussed by Purdy and Gischer 2005). Initial results show a number of non-linear relationships between basement substrate depth, lagoonal filling and volume of sand produced on the reef rims and deposited in the lagoon. Lastly, further testing of the model has revealed new challenges which are likely to manifest in any attempt at reef-scale simulation. Subtly different sets of energy direction and magnitude input parameters (different in each time step but with identical probability distributions across the entire model run) resulted in a wide range of quantitative model outputs. Time step length is a likely contributing factor and the results of further testing to address this challenge will be presented.

Flow-sediment-oyster interaction around degraded, restored, and reference oyster reefs in Florida's Indian River Lagoon

NASA Astrophysics Data System (ADS)

Kitsikoudis, V.; Kibler, K. M.; Spiering, D. W.

2017-12-01

This study analyzes flow patterns and sediment distributions around three oyster reefs in a bar-built estuarine lagoon. We studied a degraded reef, a recently restored reef, and a reference condition reef with a healthy live oyster community. The restored reef had been regraded and restored with oyster shell mats to aid in recruitment of oyster spat, with the goal of reestablishing a healthy oyster community. Despite the fact that flow-biota-sediment interaction constitutes a blossoming research field, actual field data are sparse and current knowledge emanates from flume studies and numerical modeling. Moreover, the hydraulic effect of restored oyster reefs has not been thoroughly investigated and it is not clear if the flow field and sediment erosion/deposition are similar or diverge from natural reefs. Instantaneous three-dimensional flow velocities were collected on reefs using a Nortek Vectrino Profiler and an acoustic Doppler current profiler (Nortek Aquadopp). The former measured a 2 - 3 cm velocity profile above the oyster bed, while the latter quantified incoming velocities across the flow profile approximately 10 m from the edge of the reef. Flow measurements were conducted during rising tides and are coupled with simultaneous wind speed and direction data. In addition, 20 cm deep sediment cores were retrieved on and off the investigated reefs. Sediment grain size distributions were determined after individual cores were processed for loss on ignition. Incoming flow velocities were as high as 10 cm/s, relatively higher than those recorded close to reefs. Mean and turbulent flow velocities close to the reefs, varied among the investigated sites, despite the similar wind flow conditions offshore. For instance, the measurements at the degraded reef showed decreased wave attenuation and augmented flow velocities compared to the other sites. Boat wakes exhibited a very distinct signal in the flow velocity time-series and significantly increased the approaching flow velocity at the reefs. The oyster roughness height at the restored reef (68 mm) was higher than the roughness at the reference reef (45 mm); however, the variance was higher at the latter. Sediments from degraded reef and the recently restored reef were coarser and contained less organic matter compared to the reference condition reef.

Distribution and sediment production of large benthic foraminifers on reef flats of the Majuro Atoll, Marshall Islands

NASA Astrophysics Data System (ADS)

Fujita, K.; Osawa, Y.; Kayanne, H.; Ide, Y.; Yamano, H.

2009-03-01

The distributions and population densities of large benthic foraminifers (LBFs) were investigated on reef flats of the Majuro Atoll, Marshall Islands. Annual sediment production by foraminifers was estimated based on population density data. Predominant LBFs were Calcarina and Amphistegina, and the population densities of these foraminifers varied with location and substratum type on reef flats. Both foraminifers primarily attached to macrophytes, particularly turf-forming algae, and were most abundant on an ocean reef flat (ORF) and in an inter-island channel near windward, sparsely populated islands. Calcarina density was higher on windward compared to leeward sides of ORFs, whereas Amphistegina density was similar on both sides of ORFs. These foraminifers were more common on the ocean side relative to the lagoon side of reef flats around a windward reef island, and both were rare or absent in nearshore zones around reef islands and on an ORF near windward, densely populated islands. Foraminiferal production rates varied with the degree to which habitats were subject to water motion and human influences. Highly productive sites (>103 g CaCO3 m-2 year-1) included an ORF and an inter-island channel near windward, sparsely populated islands, and a seaward area of a reef flat with no reef islands. Low-productivity sites (<10 g CaCO3 m-2 year-1) included generally nearshore zones of lagoonal reef flats, leeward ORFs, and a windward ORF near densely populated islands. These results suggest that the distribution and production of LBFs were largely influenced by a combination of natural environmental factors, including water motion, water depth, elevation relative to the lowest tidal level at spring tide, and the distribution of suitable substratum. The presence of reef islands may limit the distribution and production of foraminifers by altering water circulation in nearshore environments. Furthermore, increased anthropogenic factors (population and activities) may adversely affect foraminiferal distribution and production.

A New Perspective: Assessing the Spatial Distribution of Coral Bleaching with Unmanned Low Altitude Remote Sensing Systems

NASA Astrophysics Data System (ADS)

Levy, J.; Franklin, E. C.; Hunter, C. L.

2016-12-01

Coral reefs are biodiversity hotspots that are vital to the function of global economic and biological processes. Coral bleaching is a significant contributor to the global decline of reefs and can impact an expansive reef area over short timescales. In order to understand the dynamics of coral bleaching and how these stress events impact reef ecosystems, it is important to conduct rapid bleaching surveys at functionally important spatial scales. Due to the inherent heterogeneity, size, and in some cases, remoteness of coral reefs, it is difficult to routinely monitor coral bleaching dynamics before, during, and after bleaching. Additionally, current in situ survey methods only collect snippets of discrete reef data over small reef areas, which are unable to accurately represent the reef as a whole. We present a new technique using small unmanned aerial systems (sUAS) as cost effective, efficient monitoring tools that target small to intermediate-scale reef dynamics to understand the spatial distribution of bleached coral colonies during the 2015 bleaching event on patch reefs in Kaneohe Bay, Oahu. Overlapping low altitude aerial images were collected at four reefs during the bleaching period and processed using Structure-from-Motion techniques to produce georeferenced and spatially accurate orthomosaics of complete reef areas. Mosaics were analyzed using manual and heuristic neural network classification schemes to identify comprehensive populations of bleached and live coral on each patch reef. We found that bleached colonies had random and clumped distributions on patch reefs in Kaneohe Bay depending on local environmental conditions. Our work demonstrates that sUAS provide a low cost, efficient platform that can rapidly and repeatedly collect high-resolution imagery (1 cm/pixel) and map large areas of shallow reef ecosystems (5 hectares). This study proves the feasibility of utilizing sUAS as a tool to collect spatially rich reef data that will provide reef scientists a new perspective on meso-scale coral reef dynamics. We envision that similar low altitude aerial surveys will be incorporated as a standard component of shallow-water reef studies, especially on reefs too dangerous or remote for in situ surveys.

Assessing the spatial distribution of coral bleaching using small unmanned aerial systems

NASA Astrophysics Data System (ADS)

Levy, Joshua; Hunter, Cynthia; Lukacazyk, Trent; Franklin, Erik C.

2018-06-01

Small unmanned aerial systems (sUAS) are an affordable, effective complement to existing coral reef monitoring and assessment tools. sUAS provide repeatable low-altitude, high-resolution photogrammetry to address fundamental questions of spatial ecology and community dynamics for shallow coral reef ecosystems. Here, we qualitatively describe the use of sUAS to survey the spatial characteristics of coral cover and the distribution of coral bleaching across patch reefs in Kānéohe Bay, Hawaii, and address limitations and anticipated technology advancements within the field of UAS. Overlapping sub-decimeter low-altitude aerial reef imagery collected during the 2015 coral bleaching event was used to construct high-resolution reef image mosaics of coral bleaching responses on four Kānéohe Bay patch reefs, totaling 60,000 m2. Using sUAS imagery, we determined that paled, bleached and healthy corals on all four reefs were spatially clustered. Comparative analyses of data from sUAS imagery and in situ diver surveys found as much as 14% difference in coral cover values between survey methods, depending on the size of the reef and area surveyed. When comparing the abundance of unhealthy coral (paled and bleached) between sUAS and in situ diver surveys, we found differences in cover from 1 to 49%, depending on the depth of in situ surveys, the percent of reef area covered with sUAS surveys and patchiness of the bleaching response. This study demonstrates the effective use of sUAS surveys for assessing the spatial dynamics of coral bleaching at colony-scale resolutions across entire patch reefs and evaluates the complementarity of data from both sUAS and in situ diver surveys to more accurately characterize the spatial ecology of coral communities on reef flats and slopes.

Major Sources of Organic Matter in a Complex Coral Reef Lagoon: Identification from Isotopic Signatures (δ13C and δ15N)

PubMed Central

Briand, Marine J.; Bonnet, Xavier; Goiran, Claire; Guillou, Gaël; Letourneur, Yves

2015-01-01

A wide investigation was conducted into the main organic matter (OM) sources supporting coral reef trophic networks in the lagoon of New Caledonia. Sampling included different reef locations (fringing, intermediate and barrier reef), different associated ecosystems (mangroves and seagrass beds) and rivers. In total, 30 taxa of macrophytes, plus pools of particulate and sedimentary OM (POM and SOM) were sampled. Isotopic signatures (C and N) of each OM sources was characterized and the composition of OM pools assessed. In addition, spatial and seasonal variations of reef OM sources were examined. Mangroves isotopic signatures were the most C-depleted (-30.17 ± 0.41 ‰) and seagrass signatures were the most C-enriched (-4.36 ± 0.72 ‰). Trichodesmium spp. had the most N-depleted signatures (-0.14 ± 0.03 ‰) whereas mangroves had the most N-enriched signatures (6.47 ± 0.41 ‰). The composition of POM and SOM varied along a coast-to-barrier reef gradient. River POM and marine POM contributed equally to coastal POM, whereas marine POM represented 90% of the POM on barrier reefs, compared to 10% river POM. The relative importance of river POM, marine POM and mangroves to the SOM pool decreased from fringing to barrier reefs. Conversely, the relative importance of seagrass, Trichodesmium spp. and macroalgae increased along this gradient. Overall, spatial fluctuations in POM and SOM were much greater than in primary producers. Seasonal fluctuations were low for all OM sources. Our results demonstrated that a large variety of OM sources sustain coral reefs, varying in their origin, composition and role and suggest that δ13C was a more useful fingerprint than δ15N in this endeavour. This study also suggested substantial OM exchanges and trophic connections between coral reefs and surrounding ecosystems. Finally, the importance of accounting for environmental characteristics at small temporal and spatial scales before drawing general patterns is highlighted. PMID:26134985

Monitoring the coral disease, plague type II, on coral reefs in St. John, U.S. Virgin Islands

USGS Publications Warehouse

Miller, J.; Rogers, C.; Waara, R.

2003-01-01

In July 1997, conspicuous white patches of necrotic tissue and bare skeleton began to appear on scleractinian corals in several bays around St. John, US Virgin Islands. Analysis of diseased coral tissue from five different species confirmed the presence of a Sphingomonas-like bacterium, the pathogen for plague type II. To date, 14 species of hard corals have been affected by plague type II around St. John. This disease was monitored at Haulover and Tektite Reefs at depths of 7-12 meters. The study site at Tektite Reef has >50% cover by scleractinian corals with 90% of hard corals being composed of Montastraea annular is. Monthly surveys at Tektite Reef from December 1997 to May 2001 documented new incidence of disease (bare white patches of skeleton) every month with associated loss of living coral and 90.5% of all disease patches occurred on M. annularis. The frequency of disease within transects ranged from 3 to 58%, and the area of disease patches ranged from 0.25 to 9000 cm2. The average percent cover by the disease within 1 m2 ranged from 0.01% (?? 0.04 SD) to 1.74% (?? 9.08 SD). Photo-monitoring of 28 diseased corals of 9 species begun in September 1997 at Haulover Reef revealed no recovery of diseased portions with all necrotic tissue being overgrown rapidly by turf algae, usually within less than one month. Most coral colonies suffered partial mortality. Very limited recruitment (e.g., of Agaricia spp., Favia spp. and sponges) has been noted on the diseased areas. This coral disease has the potential to cause more loss of live coral on St. John reefs than any other stress to date because it targets the dominant reef building species, M. annularis.

Earth Observations

NASA Image and Video Library

2010-08-13

ISS024-E-011914 (13 Aug. 2010) --- Mataiva Atoll, Tuamotu Archipelago in the South Pacific Ocean is featured in this image photographed by an Expedition 24 crew member on the International Space Station. The Tuamotu Archipelago is part of French Polynesia, and forms the largest chain of atolls in the world. This photograph features Mataiva Atoll, the westernmost atoll of the Tuamotu chain. An atoll is a ring-shaped island that encloses a central lagoon. This distinctive morphology is usually associated with oceanic islands formed by volcanoes; coral reefs become established around the partially submerged volcanic cone. Over geologic time the central volcano becomes extinct, followed by erosion and subsidence beneath the sea surface, leaving the coral reefs as a ring around (or cap on) the submerged island remnant. Coral reefs exposed above the sea surface in turn experience erosion, sedimentation and soil formation, leading to the establishment of vegetation and complex ecosystems – including in many cases human habitation. Mataiva Atoll is notable in that its central lagoon includes a network of ridges (white, center) and small basins formed from eroded coral reefs. Mataiva means “nine eyes” in Tuamotuan, an allusion to nine narrow channels on the south-central portion of the island. The atoll is sparsely populated, with only a single village – Pahua – located on either side of the only pass providing constant connection between the shallow (light blue) water of the lagoon and the deeper (dark blue) adjacent Pacific Ocean. Much of the 10 kilometer-long atoll is covered with forest (greenish brown); vanilla and copra (dried coconut) are major exports from the atoll, but tourism is becoming a greater economic factor.

Earth Observations taken by the Expedition 18 Crew

NASA Image and Video Library

2009-01-27

ISS018-E-024351 (27 Jan. 2009) --- Tetiaroa Island in French Polynesia is featured in this image photographed by an Expedition 18 crewmember on the International Space Station. This island, part of the Society Islands archipelago in the southern Pacific Ocean, is also known as ?Marlon Brando?s Island?. The late film star purchased the island ? more correctly, an atoll comprised of thirteen small islets (or motus) from the French Polynesian government for a total of 70,000 over 1966-1967. While the motus were his property, the government retained the rights to the coral reefs and lagoons to preserve control of marine resources. Following Brando?s death in 2004, ownership of the approximately 8 kilometers?wide atoll passed into other private hands, and there are now plans to build a luxury resort amongst the islets. This view illustrates the typical circular appearance of a fully-developed atoll. The ring of islands ? covered in green vegetation and white to tan sandy beaches ? develops on coral reefs, which originally form around a volcanic island. As the volcanic island gradually disappears due to subsidence and erosion, the coral reefs continue to grow upwards. Over time, the central volcanic island is completely submerged, leaving a ring of coral reefs and islands that surround a lagoon. The shallow lagoon waters appear blue-green in this image, and contrast with darker ? and deeper ? Pacific Ocean waters surrounding the atoll. One of the motus in the southern portion of the atoll, Tahuna Rahi, is a protected bird sanctuary, and is the nesting site of red- and brown-footed boobies, frigatebirds, and terns (among other species). Access to the atoll is via boat, as the airstrip was closed in 2004 due to safety and security concerns.

Wave forcing and morphological changes of New Caledonia lagoon islets: Insights on their possible relations

NASA Astrophysics Data System (ADS)

Aucan, Jérôme; Vendé-Leclerc, Myriam; Dumas, Pascal; Bricquir, Marianne

2017-10-01

In the present study, we examine how waves may contribute to the morphological changes of islets in the New Caledonia lagoon. We collected in situ wave data to investigate their characteristics. Three types of waves are identified and quantified: (1) high-frequency waves generated within the lagoon, (2) low-frequency waves originating from swells in the Tasman Sea, and (3) infragravity waves. We found out that high-frequency waves are the dominant forcing on the islets during typical wind events throughout the year, while infragravity waves, likely generated by the breaking of low-frequency waves, dominate during seasonal swell events. During swell events, low-frequency waves can also directly propagate to the islets through channels across the barrier reef, or be tidally modulated across the barrier reef before reaching the islets. Topographic surveys and beach profiles on one islet indicate areas with seasonal morphological changes and other areas with longer, interannual or decadal, erosion patterns. Although more data are needed to validate this hypothesis, we suspect that a relation exists between wave forcing and morphological changes of the islets.

Great Barrier Reef, Australia

NASA Image and Video Library

1996-01-20

STS072-727-085 (11-20 Jan. 1996) --- The northern third of the Great Barrier Reef stretches 650 kilometers (km) along the coast of Queensland from south of Cairns to past Princess Charlotte Bay at the base of the Cape York Peninsula. The predominant westerly waves of the ocean create shallower (lighter-colored) convex-eastward rims to coral atolls along the outer edge of the barrier reef. In contrast, islands within the lagoon show the effect of predominant southerly, more-or-less offshore winds. Arcuate clouds suggest that winds were offshore at the time the photograph was taken.

Impact of sea-level rise and coral mortality on the wave dynamics and wave forces on barrier reefs.

PubMed

Baldock, T E; Golshani, A; Callaghan, D P; Saunders, M I; Mumby, P J

2014-06-15

A one-dimensional wave model was used to investigate the reef top wave dynamics across a large suite of idealized reef-lagoon profiles, representing barrier coral reef systems under different sea-level rise (SLR) scenarios. The modeling shows that the impacts of SLR vary spatially and are strongly influenced by the bathymetry of the reef and coral type. A complex response occurs for the wave orbital velocity and forces on corals, such that the changes in the wave dynamics vary reef by reef. Different wave loading regimes on massive and branching corals also leads to contrasting impacts from SLR. For many reef bathymetries, wave orbital velocities increase with SLR and cyclonic wave forces are reduced for certain coral species. These changes may be beneficial to coral health and colony resilience and imply that predicting SLR impacts on coral reefs requires careful consideration of the reef bathymetry and the mix of coral species. Copyright © 2014 Elsevier Ltd. All rights reserved.

Eddy covariance measurement of the spatial heterogeneity of surface energy exchanges over Heron Reef, Great Barrier Reef, Australia

NASA Astrophysics Data System (ADS)

MacKellar, M.; McGowan, H. A.; Phinn, S. R.

2011-12-01

Coral reefs cover 2.8 to 6.0 x 105 km2 of the Earth's surface and are warm, shallow regions that are believed to contribute enhanced sensible and latent heat to the atmosphere, relative to the surrounding ocean. To predict the impact of climate variability on coral reefs and their weather and climate including cloud, winds, rainfall patterns and cyclone genesis, accurate parameterisation of air-sea energy exchanges over coral reefs is essential. This is also important for the parameterisation and validation of regional to global scale forecast models to improve prediction of tropical and sub-tropical marine and coastal weather. Eddy covariance measurements of air-sea fluxes over coral reefs are rare due to the complexities of installing instrumentation over shallow, tidal water. Consequently, measurements of radiation and turbulent flux data for coral reefs have been captured remotely (satellite data) or via single measurement sites downwind of coral reefs (e.g. terrestrial or shipboard instrumentation). The resolution of such measurements and those that have been made at single locations on reefs may not capture the spatial heterogeneity of surface-atmosphere energy exchanges due to the different geomorphic and biological zones on coral reefs. Accordingly, the heterogeneity of coral reefs with regard to substrate, benthic communities and hydrodynamic processes are not considered in the characterization of the surface radiation energy flux transfers across the water-atmosphere interface. In this paper we present a unique dataset of concurrent in situ eddy covariance measurements made on instrumented pontoons of the surface energy balance over different geomorphic zones of a coral reef (shallow reef flat, shallow and deep lagoons). Significant differences in radiation transfers and air-sea turbulent flux exchanges over the reef were highlighted, with higher Bowen ratios over the shallow reef flat. Increasing wind speed was shown to increase flux divergence between sites to the extent that under unstable, south-easterly Trade Winds the net flux of heat was positive and negative over different geomorphic zones. The surface drag coefficient ranged from 1 to 2.5 x 10-3, with no significant difference between sites. Results highlight the spatial variation of air-sea energetics across a lagoonal platform reef in response to local meteorology, hydrodynamics and benthic/substrate cover.

Using Fish Population Metrics to Compare the Effects of Artificial Reef Density.

PubMed

Froehlich, Catheline Y M; Kline, Richard J

2015-01-01

Artificial reefs continue to be added as habitat throughout the world, yet questions remain about how reef design affects fish diversity and abundance. In the present study, the effects of reef density were assessed for fish communities and sizes of economically valuable Lutjanus campechanus 13 km off Port Mansfield, Texas, at a reef composed of more than 4000 concrete culverts. The study spanned from May to June in 2013 and 2014, and sites sampled included natural reefs, bare areas, and varying culvert patch density categories, ranging from 1-190 culverts. Abundances of adults and species evenness of juvenile populations differed between the years. Fish communities did not significantly differ among density categories; however, highest species richness and total abundances were observed at intermediate culvert densities and at natural reefs. Whereas the abundance of L. campechanus did not differ among density categories, mean total lengths of L. campechanus were greatest at the lower density. Our findings suggest that reefs should be deployed with intermediate patch density of 71-120 culverts in a 30-m radius to yield the highest fish abundances.

Using Fish Population Metrics to Compare the Effects of Artificial Reef Density

PubMed Central

2015-01-01

Artificial reefs continue to be added as habitat throughout the world, yet questions remain about how reef design affects fish diversity and abundance. In the present study, the effects of reef density were assessed for fish communities and sizes of economically valuable Lutjanus campechanus 13 km off Port Mansfield, Texas, at a reef composed of more than 4000 concrete culverts. The study spanned from May to June in 2013 and 2014, and sites sampled included natural reefs, bare areas, and varying culvert patch density categories, ranging from 1–190 culverts. Abundances of adults and species evenness of juvenile populations differed between the years. Fish communities did not significantly differ among density categories; however, highest species richness and total abundances were observed at intermediate culvert densities and at natural reefs. Whereas the abundance of L. campechanus did not differ among density categories, mean total lengths of L. campechanus were greatest at the lower density. Our findings suggest that reefs should be deployed with intermediate patch density of 71–120 culverts in a 30-m radius to yield the highest fish abundances. PMID:26422472

Estimating the footprint of pollution on coral reefs with models of species turnover.

PubMed

Brown, Christopher J; Hamilton, Richard J

2018-01-15

Ecological communities typically change along gradients of human impact, although it is difficult to estimate the footprint of impacts for diffuse threats such as pollution. We developed a joint model (i.e., one that includes multiple species and their interactions with each other and environmental covariates) of benthic habitats on lagoonal coral reefs and used it to infer change in benthic composition along a gradient of distance from logging operations. The model estimated both changes in abundances of benthic groups and their compositional turnover, a type of beta diversity. We used the model to predict the footprint of turbidity impacts from past and recent logging. Benthic communities far from logging were dominated by branching corals, whereas communities close to logging had higher cover of dead coral, massive corals, and soft sediment. Recent impacts were predicted to be small relative to the extensive impacts of past logging because recent logging has occurred far from lagoonal reefs. Our model can be used more generally to estimate the footprint of human impacts on ecosystems and evaluate the benefits of conservation actions for ecosystems. © 2018 Society for Conservation Biology.

Hypoxia in paradise: widespread hypoxia tolerance in coral reef fishes.

PubMed Central

Nilsson, Göran E; Ostlund-Nilsson, Sara

2004-01-01

Using respirometry, we examined the hypoxia tolerance of 31 teleost fish species (seven families) inhabiting coral reefs at a 2-5 m depth in the lagoon at Lizard Island (Great Barrier Reef, Australia). All fishes studied maintained their rate of oxygen consumption down to relatively severe hypoxia (20-30% air saturation). Indeed, most fishes appeared unaffected by hypoxia until the oxygen level fell below 10% of air saturation. This, hitherto unrecognized, hypoxia tolerance among coral reef fishes could reflect adaptations to nocturnal hypoxia in tide pools. It may also be needed to enable fishes to reside deep within branching coral at night to avoid predation. Widespread hypoxia tolerance in a habitat with such an extreme biodiversity as coral reefs indicate that there is a wealth of hypoxia related adaptations to be discovered in reef fishes. PMID:15101411

Hypoxia in paradise: widespread hypoxia tolerance in coral reef fishes.

PubMed

Nilsson, Göran E; Ostlund-Nilsson, Sara

2004-02-07

Using respirometry, we examined the hypoxia tolerance of 31 teleost fish species (seven families) inhabiting coral reefs at a 2-5 m depth in the lagoon at Lizard Island (Great Barrier Reef, Australia). All fishes studied maintained their rate of oxygen consumption down to relatively severe hypoxia (20-30% air saturation). Indeed, most fishes appeared unaffected by hypoxia until the oxygen level fell below 10% of air saturation. This, hitherto unrecognized, hypoxia tolerance among coral reef fishes could reflect adaptations to nocturnal hypoxia in tide pools. It may also be needed to enable fishes to reside deep within branching coral at night to avoid predation. Widespread hypoxia tolerance in a habitat with such an extreme biodiversity as coral reefs indicate that there is a wealth of hypoxia related adaptations to be discovered in reef fishes.

Variation in larval properties of the Atlantic brooding coral Porites astreoides between different reef sites in Bermuda

NASA Astrophysics Data System (ADS)

de Putron, Samantha J.; Lawson, Julia M.; White, Kascia Q. L.; Costa, Matthew T.; Geronimus, Miriam V. B.; MacCarthy, Anne

2017-06-01

Recent research has documented phenotypic differences among larvae released from corals with a brooding reproductive mode, both among species and within broods from a single species. We studied larvae released from the common Atlantic coral Porites astreoides in Bermuda to further evaluate phenotypic variability. Inter-site differences were investigated in larvae from conspecifics at a rim and patch reef site. Larvae were collected daily for one lunar cycle from several colonies per site each year over 5 yr. Larval volume varied with reef site of origin, with colonies from the rim reef site producing larger larvae than colonies from the patch reef site. This inter-site variation in larval size could not be explained by corallite size and may be a response to different environmental conditions at the sites. Larvae from both reef sites also varied in size depending on lunar day of release over 4 yr of study. Regardless of site of origin, smaller larvae were released earlier in the lunar cycle. Over 1 yr of study, lipid and zooxanthellae content and settlement success after 48 h covaried with larval size. However, there may be a trade-off between larger larvae and reduced fecundity. Overall, larvae released from colonies from the rim reef site were larger and had greater settlement success than those from colonies from the patch reef site. This study documents larval phenotypic variability and a distinct inter-site difference in larval ecology among conspecifics within the same geographic area, which may have implications for recruitment success, population dynamics, and resilience.

Hysteresis between coral reef calcification and the seawater aragonite saturation state

NASA Astrophysics Data System (ADS)

McMahon, Ashly; Santos, Isaac R.; Cyronak, Tyler; Eyre, Bradley D.

2013-09-01

predictions of how ocean acidification (OA) will affect coral reefs assume a linear functional relationship between the ambient seawater aragonite saturation state (Ωa) and net ecosystem calcification (NEC). We quantified NEC in a healthy coral reef lagoon in the Great Barrier Reef during different times of the day. Our observations revealed a diel hysteresis pattern in the NEC versus Ωa relationship, with peak NEC rates occurring before the Ωa peak and relatively steady nighttime NEC in spite of variable Ωa. Net ecosystem production had stronger correlations with NEC than light, temperature, nutrients, pH, and Ωa. The observed hysteresis may represent an overlooked challenge for predicting the effects of OA on coral reefs. If widespread, the hysteresis could prevent the use of a linear extrapolation to determine critical Ωa threshold levels required to shift coral reefs from a net calcifying to a net dissolving state.

Christmas Island, Line Island Group, Pacific Ocean

NASA Technical Reports Server (NTRS)

1990-01-01

Christmas Island (2.0N,158.0W), mid central Pacific Ocean, is considered to be the largest atoll in the world, about 25 km in diameter, and is part of the Line Island Group, a northwest-southeast trending chain of volcanic islands on some of the oldest ocean crust in the Pacific. The lagoon is nearly filled with reef growth leaving only a narrow entrance from the sea and large cocoanut groves are found along the fringes of the lagoon.

A multiscale analysis of coral reef topographic complexity using lidar-derived bathymetry

USGS Publications Warehouse

Zawada, D.G.; Brock, J.C.

2009-01-01

Coral reefs represent one of the most irregular substrates in the marine environment. This roughness or topographic complexity is an important structural characteristic of reef habitats that affects a number of ecological and environmental attributes, including species diversity and water circulation. Little is known about the range of topographic complexity exhibited within a reef or between different reef systems. The objective of this study was to quantify topographic complexity for a 5-km x 5-km reefscape along the northern Florida Keys reef tract, over spatial scales ranging from meters to hundreds of meters. The underlying dataset was a 1-m spatial resolution, digital elevation model constructed from lidar measurements. Topographic complexity was quantified using a fractal algorithm, which provided a multi-scale characterization of reef roughness. The computed fractal dimensions (D) are a measure of substrate irregularity and are bounded between values of 2 and 3. Spatial patterns in D were positively correlated with known reef zonation in the area. Landward regions of the study site contain relatively smooth (D ??? 2.35) flat-topped patch reefs, which give way to rougher (D ??? 2.5), deep, knoll-shaped patch reefs. The seaward boundary contains a mixture of substrate features, including discontinuous shelf-edge reefs, and exhibits a corresponding range of roughness values (2.28 ??? D ??? 2.61). ?? 2009 Coastal Education and Research Foundation.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Lighty, R.G.; Russell, K.L.

Transect mapping and petrologic studies reveal a new depositional model and limited diagenesis of a well-exposed Pleistocene reef outcrop at Ambergris Cay, northern Belize. This emergent shelf-edge reef forms a rocky wave-washed headland at the northern terminus of the present-day 250 km long flourishing Belize Barrier Reef. Previously, the Belize reef outcrop was thought to extend southward in the subsurface beneath the modern barrier reef as a Pleistocene equivalent. The authors study indicate that this outcrop is a large, coral patch reef and not part of a barrier reef trend. Sixteen transects 12.5 m apart described in continuous cm incrementsmore » from fore reef to back reef identified: extensive deposits of broken Acropora cervicornis; small thickets of A. palmata with small, oriented branches; and muddy skeletal sediments with few corals or reef rubble. Thin section and SEM studies show three phases of early submarine cementation: syntaxial and rosette aragonite; Mg-calcite rim cement and peloids; and colloidal Mg-calcite geopetal fill. Subaerial exposure in semi-arid northern Belize caused only minor skeletal dissolution, some precipitation of vadose whisker calcite, and no meteoric phreatic diagenesis. Facies geometry, coral assemblages, lack of rubble deposits, coralline algal encrustations and Millepora framework, and recognition of common but discrete submarine cements, all indicate that this Pleistocene reef was an isolated, coral-fringed sediment buildup similar to may large patch reefs existing today in moderate-energy shelf environments behind the modern barrier reef in central and southern Belize.« less

Drivers of pCO2 variability in two contrasting coral reef lagoons: The influence of submarine groundwater discharge

NASA Astrophysics Data System (ADS)

Cyronak, Tyler; Santos, Isaac R.; Erler, Dirk V.; Maher, Damien T.; Eyre, Bradley D.

2014-04-01

The impact of groundwater on pCO2 variability was assessed in two coral reef lagoons with distinct drivers of submarine groundwater discharge (SGD). Diel variability of pCO2 in the two ecosystems was explained by a combination of biological drivers and SGD inputs. In Rarotonga, a South Pacific volcanic island, 222Rn-derived SGD was driven primarily by a steep terrestrial hydraulic gradient, and the water column was influenced by the high pCO2 (5501 µatm) of the fresh groundwater. In Heron Island, a Great Barrier Reef coral cay, SGD was dominated by seawater recirculation through the sediments (i.e., tidal pumping), and pCO2 was mainly impacted through the stimulation of biological processes. The Rarotonga water column had a higher average pCO2 (549 µatm) than Heron Island (471 µatm). However, pCO2 exhibited a greater diel range in Heron Island (778 µatm) than in Rarotonga (507 µatm). The Rarotonga water column received 29.0 ± 8.2 mmol free-CO2 m-2 d-1 from SGD, while the Heron Island water column received 12.1 ± 4.2 mmol free-CO2 m-2 d-1. Over the course of this study, both systems were sources of CO2 to the atmosphere with SGD-derived free-CO2 most likely contributing a large portion to the air-sea CO2 flux. Studies measuring the carbon chemistry of coral reefs (e.g., metabolism and calcification rates) may need to consider the effects of groundwater inputs on water column carbonate chemistry. Local drivers of coral reef carbonate chemistry such as SGD may offer more approachable management solutions to mitigating the effects of ocean acidification on coral reefs.

Small-Boat Noise Impacts Natural Settlement Behavior of Coral Reef Fish Larvae.

PubMed

Simpson, Stephen D; Radford, Andrew N; Holles, Sophie; Ferarri, Maud C O; Chivers, Douglas P; McCormick, Mark I; Meekan, Mark G

2016-01-01

After a pelagic larval phase, settlement-stage coral reef fish must locate a suitable reef habitat for juvenile life. Reef noise, produced by resident fish and invertebrates, provides an important cue for orientation and habitat selection during this process, which must often occur in environments impacted by anthropogenic noise. We adapted an established field-based protocol to test whether recorded boat noise influenced the settlement behavior of reef fish. Fewer fish settled to patch reefs broadcasting boat + reef noise compared with reef noise alone. This study suggests that boat noise, now a common feature of many reefs, can compromise critical settlement behavior of reef fishes.

Quantifying coastal connectivity of coral spawn and larvae around Ryukyu Islands in the East China Sea

NASA Astrophysics Data System (ADS)

Odani, S.; Uchiyama, Y.; Kashima, M.; Kamidaira, Y.; Mitarai, S.

2016-12-01

Ryukyu Islands in the East China Sea are in a subtropical climate, hosting desirable environment for abundant coral ecosystem. Okinawa Main Island is the most densely populated island among them with tremendous tourist attractions including enchanting coral reefs and beaches. Kamidaira et al. (2016) suggested that the Kuroshio warm water maintains warmer water temperature favorable to corals around the island due mainly to intermittent eddy heat transport. It is presumed that the Kuroshio and associated eddy mixing also promote the transport and dispersal of coral spawn and larvae across the islands, whereas the area has suffered from coral breeching in the recent decades. Therefore, for optimal preservation and protection of the coral habitats around Ryukyu Island, we conduct a double nested high-resolution synoptic ocean modeling using ROMS with grid spacing down to 1 km coupled with an offline Lagrangian particle tracking model to investigate dispersal of coral spawn and larvae released from about 20 major islands and lagoons. Based on the model outcome, we quantify connectivity using Lagrangian probability density functions (PDFs) of the Lagrangian particles (e.g., Mitarai et al., 2009) among Ryukyu Islands. We then focus on the larval dispersal released from Sekisei Lagoon in Yaeyama Islands close to Taiwan, where we have carried out a series of in-situ surface drifter measurement. To compare the observation with the model, 160 source and sink patches with a diameter of 3 km are defined around Sekisei Lagoon and Okinawa Main Island for quantification of the detailed connectivity between them. The advection time is assumed for no more than 3 weeks to represent the lifespan of coral spawn and larvae. A PDF analysis suggests that the particles mostly remain near the released areas with predominant clockwise circulation around the lagoon, while approximately less than 5 % of particles are trapped and transported northeastward in long distance by the Kuroshio. The trajectories show that some of these particles are transported to approach Okinawa Main Island while some are trapped by eddies between the Kuroshio and the island, suggesting that eddies act to promote both particle beaching on the islands as well as trapping in the offshore.

Understanding Biophysical Interactions In The Great Barrier Reef Catchments: Better Landscape Management For Water Quality Outcomes

NASA Astrophysics Data System (ADS)

Bui, E. N.; Wilkinson, S. N.; Bartley, R.

2014-12-01

Sediment input to the Great Barrier Reef (GBR) lagoon has had deleterious impacts on seagrass and coral ecosystems. The response of the Australian government has been to develop policies to: (i) reverse the impact of threats from sediments and nutrients, and improve water quality and aquatic health of the GBR lagoon; and (ii) to facilitate the uptake of sustainable farming and land management practices that deliver improved ecosystem services, by at least 30 per cent of farmers. The Reef2050 Long term sustainability plan aims to identify priority locations for on-ground investment of remediation options that will result in a reduction of constituent loads to the GBR. Recent sediment tracing studies indicate that subsoil from erosion features such as gullies and channel banks are the dominant contributors of sediment in the GBR catchments. Better control of gully and streambank erosion and restoration of riparian habitats are therefore necessary. Here we review the evidence for bank erosion in the GBR catchments and how scientific evidence on feedback relationships between climate- geochemistry-vegetation-landforms can be used to develop better guidelines for streambank and gully re-vegetation.

50 CFR 622.2 - Definitions and acronyms.

Code of Federal Regulations, 2014 CFR

2014-10-01

... where coral growth abounds, including patch reefs, outer bank reefs, deep water banks, and hard bottoms... muscle tissue, of a spiny lobster along the top middorsal line (middle of the back) to the rearmost...

Temperature Regimes Impact Coral Assemblages along Environmental Gradients on Lagoonal Reefs in Belize

PubMed Central

Townsend, Joseph E.; Courtney, Travis A.; Aichelman, Hannah E.; Davies, Sarah W.; Lima, Fernando P.; Castillo, Karl D.

2016-01-01

Coral reefs are increasingly threatened by global and local anthropogenic stressors such as rising seawater temperature, nutrient enrichment, sedimentation, and overfishing. Although many studies have investigated the impacts of local and global stressors on coral reefs, we still do not fully understand how these stressors influence coral community structure, particularly across environmental gradients on a reef system. Here, we investigate coral community composition across three different temperature and productivity regimes along a nearshore-offshore gradient on lagoonal reefs of the Belize Mesoamerican Barrier Reef System (MBRS). A novel metric was developed using ultra-high-resolution satellite-derived estimates of sea surface temperatures (SST) to classify reefs as exposed to low (lowTP), moderate (modTP), or high (highTP) temperature parameters over 10 years (2003 to 2012). Coral species richness, abundance, diversity, density, and percent cover were lower at highTP sites relative to lowTP and modTP sites, but these coral community traits did not differ significantly between lowTP and modTP sites. Analysis of coral life history strategies revealed that highTP sites were dominated by hardy stress-tolerant and fast-growing weedy coral species, while lowTP and modTP sites consisted of competitive, generalist, weedy, and stress-tolerant coral species. Satellite-derived estimates of Chlorophyll-a (chl-a) were obtained for 13-years (2003–2015) as a proxy for primary production. Chl-a concentrations were highest at highTP sites, medial at modTP sites, and lowest at lowTP sites. Notably, thermal parameters correlated better with coral community traits between site types than productivity, suggesting that temperature (specifically number of days above the thermal bleaching threshold) played a greater role in defining coral community structure than productivity on the MBRS. Dominance of weedy and stress-tolerant genera at highTP sites suggests that corals utilizing these two life history strategies may be better suited to cope with warmer oceans and thus may warrant protective status under climate change. PMID:27606598

Temperature Regimes Impact Coral Assemblages along Environmental Gradients on Lagoonal Reefs in Belize.

PubMed

Baumann, Justin H; Townsend, Joseph E; Courtney, Travis A; Aichelman, Hannah E; Davies, Sarah W; Lima, Fernando P; Castillo, Karl D

2016-01-01

Coral reefs are increasingly threatened by global and local anthropogenic stressors such as rising seawater temperature, nutrient enrichment, sedimentation, and overfishing. Although many studies have investigated the impacts of local and global stressors on coral reefs, we still do not fully understand how these stressors influence coral community structure, particularly across environmental gradients on a reef system. Here, we investigate coral community composition across three different temperature and productivity regimes along a nearshore-offshore gradient on lagoonal reefs of the Belize Mesoamerican Barrier Reef System (MBRS). A novel metric was developed using ultra-high-resolution satellite-derived estimates of sea surface temperatures (SST) to classify reefs as exposed to low (lowTP), moderate (modTP), or high (highTP) temperature parameters over 10 years (2003 to 2012). Coral species richness, abundance, diversity, density, and percent cover were lower at highTP sites relative to lowTP and modTP sites, but these coral community traits did not differ significantly between lowTP and modTP sites. Analysis of coral life history strategies revealed that highTP sites were dominated by hardy stress-tolerant and fast-growing weedy coral species, while lowTP and modTP sites consisted of competitive, generalist, weedy, and stress-tolerant coral species. Satellite-derived estimates of Chlorophyll-a (chl-a) were obtained for 13-years (2003-2015) as a proxy for primary production. Chl-a concentrations were highest at highTP sites, medial at modTP sites, and lowest at lowTP sites. Notably, thermal parameters correlated better with coral community traits between site types than productivity, suggesting that temperature (specifically number of days above the thermal bleaching threshold) played a greater role in defining coral community structure than productivity on the MBRS. Dominance of weedy and stress-tolerant genera at highTP sites suggests that corals utilizing these two life history strategies may be better suited to cope with warmer oceans and thus may warrant protective status under climate change.

Mortality of shallow reef corals in the western Arabian Gulf following aerial exposure in winter

NASA Astrophysics Data System (ADS)

Fadlallah, Y. H.; Allen, K. W.; Estudillo, R. A.

1995-05-01

Aerial exposure of patch reef corals occurred in Tarut Bay, western Arabian Gulf, (Saudi Arabia) between December 1991 and May 1992, and coincided with extreme low spring tides (below the predicted lowest astronomical tide-LAT). Colonies of Acropora and Stylophora occurring at the highest levels on the tops of patch reef platforms were most affected by the low tides. Corals fully exposed to air suffered total mortality, whereas those not fully exposed suffered tissue damage to their upper parts. Exposure occurred during winter months when air and water temperatures are at their lowest in the gulf. Coupling of extremely low spring tides with wind-induced negative surges (below LAT) are not regular events but are not infrequent. Cold temperatures and exposure may act in concert to produce disproportionate mortalities of reef flat corals in the shallow coastal areas of eastern Saudi Arabia. It is highly unlikely that the Gulf War oil spill played any role in the observed damage to reef corals in the Gulf in 1992.

Species-area relationships in coral communities: evaluating mechanisms for a commonly observed pattern

NASA Astrophysics Data System (ADS)

Huntington, B. E.; Lirman, D.

2012-12-01

Landscape-scale attributes of patch size, spatial isolation, and topographic complexity are known to influence diversity and abundance in terrestrial and marine systems, but remain collectively untested for reef-building corals. To investigate the relationship between the coral assemblage and seascape variation in reef habitats, we took advantage of the distinct boundaries, spatial configurations, and topographic complexities among artificial reef patches to overcome the difficulties of manipulating natural reefs. Reef size (m2) was found to be the foremost predictor of coral richness in accordance with species-area relationship predictions. Larger reefs were also found to support significantly higher colony densities, enabling us to reject the null hypothesis of random placement (a sampling artifact) in favor of target area predictions that suggest greater rates of immigration on larger reefs. Unlike the pattern previously documented for reef fishes, topographic complexity was not a significant predictor of any coral assemblage response variable, despite the range of complexity values sampled. Lastly, coral colony density was best explained by both increasing reef size and decreasing reef spatial isolation, a pattern found exclusively among brooding species with shorter larval dispersal distances. We conclude that seascape attributes of reef size and spatial configuration within the seascape can influence the species richness and abundance of the coral community at relatively small spatial scales (<1 km). Specifically, we demonstrate how patterns in the coral communities that have naturally established on these manipulated reefs agree with the target area and island biogeography mechanisms to drive species-area relationships in reef-building corals. Based on the patterns documented in artificial reefs, habitat degradation that results in smaller, more isolated natural reefs may compromise coral diversity.

New maps, new information: Coral reefs of the Florida keys

USGS Publications Warehouse

Lidz, B.H.; Reich, C.D.; Peterson, R.L.; Shinn, E.A.

2006-01-01

A highly detailed digitized map depicts 22 benthic habitats in 3140.5 km2 of the Florida Keys National Marine Sanctuary. Dominant are a seagrass/lime-mud zone (map area 27.5%) throughout Hawk Channel and seagrass/carbonate-sand (18.7%) and bare carbonate-sand (17.3%) zones on the outer shelf and in The Quicksands. A lime-mud/seagrass-covered muddy carbonate-sand zone (9.6%) abuts the keys. Hardbottom communities (13.2%) consist of bare Pleistocene coralline and oolitic limestone, coral rubble, and senile coral reefs. Smaller terrestrial (4.0%) and marine habitats, including those of live coral (patch reefs, 0.7%), account for the rest (13.7%) of the area. Derived from aerial photomosaics, the seabed dataset fits precisely when transposed onto a newly developed National Geophysical Data Center hydrographic-bathymetry map. Combined, the maps point to new information on unstudied seabed morphologies, among them an erosional nearshore rock ledge bordering the seaward side of the Florida Keys and thousands of patch-reef clusters aligned in mid-Hawk Channel. Preliminary indications are that the ledge may represent the seaward extent of the 125-ka Key Largo and Miami Limestone that form the keys, and the patch reefs colonized landward edges of two noncoralline, non-dune-ridge topographic troughs. The troughs, their substrate, and inner-shelf location along the seaward side of the Hawk Channel bedrock depression are the first of that type of nuclei to be recognized in the Florida reef record. Together, the map datasets establish the efficacy and accuracy of using aerial photographs to define in extraordinary detail the seabed features and habitats in a shallow-reef setting.

The 2004 Indian Ocean Tsunami in Maldives: waves and disaster affected by shape of coral reefs and islands

NASA Astrophysics Data System (ADS)

Kan, H.; Ali, M.; Riyaz, M.

2005-12-01

In Maldives, 39 islands are significantly damaged among 200 inhabited islands and nearly a third of the Maldivian people are severely affected by the Indian Ocean Tsunami in 26 December 2004. We surveyed tsunami impact in 43 islands by measuring island topography and run-up height, interview to local people and mapping of the flooded and destructed areas. The differences in tsunami height and disaster corresponding to the atoll shape and island topography are observed. In the northern atolls, atoll rims consist of many ring-shaped reefs, i.e. miniature atolls called `faro', and interrupted many channels between them. The interrupted atoll rim may play an important role to reducing tsunami run-up height. Severe damage was not observed in the eastern coast of the islands. Beach ridge also contribute to the protection against tsunami. However, in some islands, houses beside the lagoon are damaged by backwashing floodwater from the lagoon. Water marks show the run-up height of -1.8m above MSL. The lagoon water-level seems to set-up by tsunami which permeates into the lagoon through the interrupted atoll rim. The disaster was severe at the southern atolls of Meemu, Thaa and Laamu. The higher run-up heights of up to 3.2m above MSL and enormous building damages were observed at the islands on the eastern atoll rims. The continuous atoll rim of these atolls may reinforce tsunami impact at the eastern islands. In addition, tsunami surge washed the islands totally because of low island topography without beach ridge. Significant floodwater from lagoon was not observed in these atolls. It seems the lagoon water-level was not set-up largely. The continuous atoll rim reduces the tsunami influence to the lagoon and the western side of the atolls. The continuity of atoll rim is probably the major factor to cause the difference in water movement, i.e. tsunami run-up and lagoon set-up, which affects the disaster in the islands. Beach ridge contribute to reduce the tsunami impact to the settlement and agricultural land. Our results may elucidate secure atoll and island type to mitigate the risk of future tsunamis on atoll nations/districts in the Pacific and the Indian Ocean.

Anthropogenic mortality on coral reefs in Caribbean Panama predates coral disease and bleaching.

PubMed

Cramer, Katie L; Jackson, Jeremy B C; Angioletti, Christopher V; Leonard-Pingel, Jill; Guilderson, Thomas P

2012-06-01

Caribbean reef corals have declined precipitously since the 1980s due to regional episodes of bleaching, disease and algal overgrowth, but the extent of earlier degradation due to localised historical disturbances such as land clearing and overfishing remains unresolved. We analysed coral and molluscan fossil assemblages from reefs near Bocas del Toro, Panama to construct a timeline of ecological change from the 19th century-present. We report large changes before 1960 in coastal lagoons coincident with extensive deforestation, and after 1960 on offshore reefs. Striking changes include the demise of previously dominant staghorn coral Acropora cervicornis and oyster Dendrostrea frons that lives attached to gorgonians and staghorn corals. Reductions in bivalve size and simplification of gastropod trophic structure further implicate increasing environmental stress on reefs. Our paleoecological data strongly support the hypothesis, from extensive qualitative data, that Caribbean reef degradation predates coral bleaching and disease outbreaks linked to anthropogenic climate change. © 2012 Blackwell Publishing Ltd/CNRS.

Global variations of large megathrust earthquake rupture characteristics

PubMed Central

Kanamori, Hiroo

2018-01-01

Despite the surge of great earthquakes along subduction zones over the last decade and advances in observations and analysis techniques, it remains unclear whether earthquake complexity is primarily controlled by persistent fault properties or by dynamics of the failure process. We introduce the radiated energy enhancement factor (REEF), given by the ratio of an event’s directly measured radiated energy to the calculated minimum radiated energy for a source with the same seismic moment and duration, to quantify the rupture complexity. The REEF measurements for 119 large [moment magnitude (Mw) 7.0 to 9.2] megathrust earthquakes distributed globally show marked systematic regional patterns, suggesting that the rupture complexity is strongly influenced by persistent geological factors. We characterize this as the existence of smooth and rough rupture patches with varying interpatch separation, along with failure dynamics producing triggering interactions that augment the regional influences on large events. We present an improved asperity scenario incorporating both effects and categorize global subduction zones and great earthquakes based on their REEF values and slip patterns. Giant earthquakes rupturing over several hundred kilometers can occur in regions with low-REEF patches and small interpatch spacing, such as for the 1960 Chile, 1964 Alaska, and 2011 Tohoku earthquakes, or in regions with high-REEF patches and large interpatch spacing as in the case for the 2004 Sumatra and 1906 Ecuador-Colombia earthquakes. Thus, combining seismic magnitude Mw and REEF, we provide a quantitative framework to better represent the span of rupture characteristics of great earthquakes and to understand global seismicity. PMID:29750186

The Shark Assemblage at French Frigate Shoals Atoll, Hawai‘i: Species Composition, Abundance and Habitat Use

PubMed Central

Dale, Jonathan J.; Stankus, Austin M.; Burns, Michael S.; Meyer, Carl G.

2011-01-01

Empirical data on the abundance and habitat preferences of coral reef top predators are needed to evaluate their ecological impacts and guide management decisions. We used longline surveys to quantify the shark assemblage at French Frigate Shoals (FFS) atoll from May to August 2009. Fishing effort consisted of 189 longline sets totaling 6,862 hook hours of soak time. A total of 221 sharks from 7 species were captured, among which Galapagos (Carcharhinus galapagensis, 36.2%), gray reef (Carcharhinus amblyrhynchos, 25.8%) and tiger (Galeocerdo cuvier, 20.4%) sharks were numerically dominant. A lack of blacktip reef sharks (Carcharhinus melanopterus) distinguished the FFS shark assemblage from those at many other atolls in the Indo-Pacific. Compared to prior underwater visual survey estimates, longline methods more accurately represented species abundance and composition for the majority of shark species. Sharks were significantly less abundant in the shallow lagoon than adjacent habitats. Recaptures of Galapagos sharks provided the first empirical estimate of population size for any Galapagos shark population. The overall recapture rate was 5.4%. Multiple closed population models were evaluated, with Chao Mh ranking best in model performance and yielding a population estimate of 668 sharks with 95% confidence intervals ranging from 289–1720. Low shark abundance in the shallow lagoon habitats suggests removal of a small number of sharks from the immediate vicinity of lagoonal islets may reduce short-term predation on endangered monk seal (Monachus schauinslandi) pups, but considerable fishing effort would be required to catch even a small number of sharks. Additional data on long-term movements and habitat use of sharks at FFS are required to better assess the likely ecological impacts of shark culling. PMID:21347321

The shark assemblage at French Frigate Shoals atoll, Hawai'i: species composition, abundance and habitat use.

PubMed

Dale, Jonathan J; Stankus, Austin M; Burns, Michael S; Meyer, Carl G

2011-02-10

Empirical data on the abundance and habitat preferences of coral reef top predators are needed to evaluate their ecological impacts and guide management decisions. We used longline surveys to quantify the shark assemblage at French Frigate Shoals (FFS) atoll from May to August 2009. Fishing effort consisted of 189 longline sets totaling 6,862 hook hours of soak time. A total of 221 sharks from 7 species were captured, among which Galapagos (Carcharhinus galapagensis, 36.2%), gray reef (Carcharhinus amblyrhynchos, 25.8%) and tiger (Galeocerdo cuvier, 20.4%) sharks were numerically dominant. A lack of blacktip reef sharks (Carcharhinus melanopterus) distinguished the FFS shark assemblage from those at many other atolls in the Indo-Pacific. Compared to prior underwater visual survey estimates, longline methods more accurately represented species abundance and composition for the majority of shark species. Sharks were significantly less abundant in the shallow lagoon than adjacent habitats. Recaptures of Galapagos sharks provided the first empirical estimate of population size for any Galapagos shark population. The overall recapture rate was 5.4%. Multiple closed population models were evaluated, with Chao M(h) ranking best in model performance and yielding a population estimate of 668 sharks with 95% confidence intervals ranging from 289-1720. Low shark abundance in the shallow lagoon habitats suggests removal of a small number of sharks from the immediate vicinity of lagoonal islets may reduce short-term predation on endangered monk seal (Monachus schauinslandi) pups, but considerable fishing effort would be required to catch even a small number of sharks. Additional data on long-term movements and habitat use of sharks at FFS are required to better assess the likely ecological impacts of shark culling.

Facies dimensions within carbonate reservoirs - guidelines from satellite images of modern analogs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Harris, P.M.; Kowalik, W.S.

1995-08-01

Modern analogs illustrate the distribution of carbonate facies within an overall depositional setting and can be an integral part of a subsurface geologic model in indicating the dimensions, trend, and interrelationships of facies that might be related to reservoir and non-reservoir distribution. Satellite images from several modern carbonate areas depict the geologic characteristics that can be expected in ancient shallow-water settings. Isolated carbonate platforms- the Bahamas, Caicos Platform in the British West Indies, Chinchorro Bank offshore of Yucatan, and portions of the Belize area; Ramp-style shelf-to-basin transitions - Abu Dhabi and northern Yucatan; Rimmed shelf margins - South Florida, portionsmore » of Belize, and the Great Barrier Reef of Australia; Broad, deep shelf lagoons - the Great Barrier Reef and Belize; Reef variability - South Florida, the Bahamas, Caicos, Northern Yucatan, and Abu Dhabi; Shallow lagoon/tidal flat settings - South Florida, the Bahamas, Caicos, Northern Yucatan, Shark Bay in Western Australia, Abu Dhabi; Mixed carbonate and siliciclastic depostion - South Florida, Belize, the Great Barrier Reef, Shark Bay and Abu Dhabi. The geologic framework as illustrated by these areas is important at the development scale where lateral variation of porosity and permeability, i.e. reservoir quality, is commonly tied to facies changes and facies dimensions are required as input to reservoir models. The geologic framework is essential at the exploration scale for reservoir facies prediction and stratigraphic play concepts which are related directly to depositional facies patterns.« less

Scenario-based numerical modelling and the palaeo-historic record of tsunamis in Wallis and Futuna, Southwest Pacific

NASA Astrophysics Data System (ADS)

Lamarche, G.; Popinet, S.; Pelletier, B.; Mountjoy, J.; Goff, J.; Delaux, S.; Bind, J.

2015-08-01

We investigated the tsunami hazard in the remote French territory of Wallis and Futuna, Southwest Pacific, using the Gerris flow solver to produce numerical models of tsunami generation, propagation and inundation. Wallis consists of the inhabited volcanic island of Uvéa that is surrounded by a lagoon delimited by a barrier reef. Futuna and the island of Alofi form the Horn Archipelago located ca. 240 km east of Wallis. They are surrounded by a narrow fringing reef. Futuna and Alofi emerge from the North Fiji Transform Fault that marks the seismically active Pacific-Australia plate boundary. We generated 15 tsunami scenarios. For each, we calculated maximum wave elevation (MWE), inundation distance and expected time of arrival (ETA). The tsunami sources were local, regional and distant earthquake faults located along the Pacific Rim. In Wallis, the outer reef may experience 6.8 m-high MWE. Uvéa is protected by the barrier reef and the lagoon, but inundation depths of 2-3 m occur in several coastal areas. In Futuna, flow depths exceeding 2 m are modelled in several populated areas, and have been confirmed by a post-September 2009 South Pacific tsunami survey. The channel between the islands of Futuna and Alofi amplified the 2009 tsunami, which resulted in inundation distance of almost 100 m and MWE of 4.4 m. This first ever tsunami hazard modelling study of Wallis and Futuna compares well with palaeotsunamis recognised on both islands and observation of the impact of the 2009 South Pacific tsunami. The study provides evidence for the mitigating effect of barrier and fringing reefs from tsunamis.

Scenario-based numerical modelling and the palaeo-historic record of tsunamis in Wallis and Futuna, Southwest Pacific

NASA Astrophysics Data System (ADS)

Lamarche, G.; Popinet, S.; Pelletier, B.; Mountjoy, J.; Goff, J.; Delaux, S.; Bind, J.

2015-04-01

We investigated the tsunami hazard in the remote French territory of Wallis and Futuna, Southwest Pacific, using the Gerris flow solver to produce numerical models of tsunami generation, propagation and inundation. Wallis consists of the inhabited volcanic island of Uvéa that is surrounded by a lagoon delimited by a barrier reef. Futuna and the island of Alofi forms the Horn Archipelago located ca. 240 km east of Wallis. They are surrounded by a narrow fringing reef. Futuna and Alofi emerge from the North Fiji Transform Fault that marks the seismically active Pacific-Australia plate boundary. We generated fifteen tsunami scenarios. For each, we calculated maximum wave elevation (MWE), inundation distance, and Expected Time of Arrival (ETA). The tsunami sources were local, regional and distant earthquake faults located along the Pacific Rim. In Wallis, the outer reef may experience 6.8 m-high MWE. Uvéa is protected by the barrier reef and the lagoon, but inundation depths of 2-3 m occur in several coastal areas. In Futuna, flow depths exceeding 2 m are modelled in several populated areas, and have been confirmed by a post-September 2009 South Pacific tsunami survey. The channel between the islands of Futuna and Alofi amplified the 2009 tsunami, which resulted in inundation distance of almost 100 m and MWE of 4.4 m. This first-ever tsunami hazard modelling study of Wallis and Futuna compares well with palaeotsunamis recognised on both islands and observation of the impact of the 2009 South Pacific tsunami. The study provides evidence for the mitigating effect of barrier and fringing reefs from tsunamis.

Evidence of chronic anthropogenic nutrient within coastal lagoon reefs adjacent to urban and tourism centers, Kenya: A stable isotope approach.

PubMed

Mwaura, Jelvas; Umezawa, Yu; Nakamura, Takashi; Kamau, Joseph

2017-06-30

The source of anthropogenic nutrient and its spatial extent in three fringing reefs with differing human population gradients in Kenya were investigated using stable isotope approaches. Nutrient concentrations and nitrate-δ 15 N in seepage water indicated that population density and tourism contributed greatly to the extent of nutrient loading to adjacent reefs. Although water-column nutrient analyses did not show any significant difference among the reefs, higher δ 15 N and N contents in macrophytes showed terrestrial nutrients affected primary producers in onshore areas in Nyali and Bamburi reefs, but were mitigated by offshore water intrusion especially at Nyali. On the offshore reef flat, where the same species of macroalgae were not available, complementary use of δ 15 N in sedimentary organic matter suggested inputs of nutrients originated from the urban city of Mombasa. If population increases in the future, nutrient conditions in the shallower reef, Vipingo, may be dramatically degraded due to lower water exchange ratio. Copyright © 2017 Elsevier Ltd. All rights reserved.

The Economic Value of Coastal Ecosystems in California

EPA Science Inventory

The status of marine ecosystems affects the well being of human societies. These ecosystems include but are not limited to estuaries, lagoons, reefs, and systems further offshore such as deep ocean vents. The coastal regions that connect terrestrial and marine ecosystems are of p...

Skeletal records of community-level bleaching in Porites corals from Palau

NASA Astrophysics Data System (ADS)

Barkley, Hannah C.; Cohen, Anne L.

2016-12-01

Tropical Pacific sea surface temperature is projected to rise an additional 2-3 °C by the end of this century, driving an increase in the frequency and intensity of coral bleaching. With significant global coral reef cover already lost due to bleaching-induced mortality, efforts are underway to identify thermally tolerant coral communities that might survive projected warming. Massive, long-lived corals accrete skeletal bands of anomalously high density in response to episodes of thermal stress. These "stress bands" are potentially valuable proxies for thermal tolerance, but to date their application to questions of community bleaching history has been limited. Ecological surveys recorded bleaching of coral communities across the Palau archipelago during the 1998 and 2010 warm events. Between 2011 and 2015, we extracted skeletal cores from living Porites colonies at 10 sites spanning barrier reef and lagoon environments and quantified the proportion of stress bands present in each population during bleaching years. Across Palau, the prevalence of stress bands tracked the severity of thermal stress, with more stress bands occurring in 1998 (degree heating weeks = 13.57 °C-week) than during the less severe 2010 event (degree heating weeks = 4.86 °C-week). Stress band prevalence also varied by reef type, as more corals on the exposed barrier reef formed stress bands than did corals from sheltered lagoon environments. Comparison of Porites stress band prevalence with bleaching survey data revealed a strong correlation between percent community bleaching and the proportion of colonies with stress bands in each year. Conversely, annual calcification rates did not decline consistently during bleaching years nor did annually resolved calcification histories always track interannual variability in temperature. Our data suggest that stress bands in massive corals contain valuable information about spatial and temporal trends in coral reef bleaching and can aid in conservation efforts to identify temperature-tolerant coral reef communities.

Is proximity to land-based sources of coral stressors an appropriate measure of risk to coral reefs? An example from the Florida Reef Tract.

PubMed

Lirman, Diego; Fong, Peggy

2007-06-01

Localized declines in coral condition are commonly linked to land-based sources of stressors that influence gradients of water quality, and the distance to sources of stressors is commonly used as a proxy for predicting the vulnerability and future status of reef resources. In this study, we evaluated explicitly whether proximity to shore and connections to coastal bays, two measures of potential land-based sources of disturbance, influence coral community and population structure, and the abundance, distribution, and condition of corals within patch reefs of the Florida Reef Tract. In the Florida Keys, long-term monitoring has documented significant differences in water quality along a cross-shelf gradient. Inshore habitats exhibit higher levels of nutrients (DIN and TP), TOC, turbidity, and light attenuation, and these levels decrease with increasing distance from shore and connections to tidal bays. In clear contrast to these patterns of water quality, corals on inshore patch reefs exhibited significantly higher coral cover, higher growth rates, and lower partial mortality rates than those documented in similar offshore habitats. Coral recruitment rates did not differ between inshore and offshore habitats. Corals on patch reefs closest to shore had well-spread population structures numerically dominated by intermediate to large colonies, while offshore populations showed narrower size-distributions that become increasingly positively skewed. Differences in size-structure of coral populations were attributed to faster growth and lower rates of partial mortality at inshore habitats. While the underlying causes for the favorable condition of inshore coral communities are not yet known, we hypothesize that the ability of corals to shift their trophic mode under adverse environmental conditions may be partly responsible for the observed patterns, as shown in other reef systems. This study, based on data collected from a uniform reef habitat type and coral species with diverse life-history and stress-response patterns from a heavily exploited reef system, showed that proximity to potential sources of stressors may not always prove an adequate proxy for assigning potential risks to reef health, and that hypothesized patterns of coral cover, population size-structure, growth, and mortality are not always directly related to water quality gradients.

Observation of coral reefs on Ishigaki Island, Japan, using Landsat TM images and aerial photographs

DOE Office of Scientific and Technical Information (OSTI.GOV)

Matsunaga, Tsuneo; Kayanne, Hajime

1997-06-01

Ishigaki Island is located at the southwestern end of Japanese Islands and famous for its fringing coral reefs. More than twenty LANDSAT TM images in twelve years and aerial photographs taken on 1977 and 1994 were used to survey two shallow reefs on this island, Shiraho and Kabira. Intensive field surveys were also conducted in 1995. All satellite images of Shiraho were geometrically corrected and overlaid to construct a multi-date satellite data set. The effects of solar elevation and tide on satellite imagery were studied with this data set. The comparison of aerial and satellite images indicated that significant changesmore » occurred between 1977 and 1984 in Kabira: rapid formation in the western part and decrease in the eastern part of dark patches. The field surveys revealed that newly formed dark patches in the west contain young corals. These results suggest that remote sensing is useful for not only mapping but also monitoring of shallow coral reefs.« less

Astronaut Photography of Coral Reefs

NASA Technical Reports Server (NTRS)

Robinson, Julie A.; Noordeloos, Marco

2001-01-01

Astronaut photographs of tropical coastal areas may contain information on submerged features, including coral reefs, up to depths of about 15 m in clear waters. Previous research efforts have shown that astronaut photographs can aid in estimating coral reef locations and extent on national, regional and global scales, and allow characterization of major geomorphological rim and lagoon features (Andrefouet et al. 2000, in preparation). They can be combined with traditional satellite data to help distinguish between clouds and lagoon features such as pinnacles (Andrefouet and Robinson, in review). Furthermore, astronaut photographs may provide reef scientists and managers with information on the location and extent of river plumes and sediment run off, or facilitate identification of land cover types, including mangroves (Webb et al., in press). Photographs included in the section were selected based on several criteria. The primary consideration of the editors was that the photographs represent a worldwide distribution of coral reefs, have extremely low visual interference by cloud cover, and display a spatial scale reasonable for examining reef-related features. Once photographs were selected, they were digitized from 2nd generation copies. The color and contrast were hand corrected to an approximation of natural color (required to account for spectral differences between photographs due to the color sensitivities of films used, and differences in sun angle and exposure of the photographs). None of the photographs shown here have been georeferenced to correct them to a map projection and scale. Any distortions in features due to slightly oblique look angles when the photographs were taken through spacecraft windows remain. When feasible, near vertical photographs have been rotated so that north is toward the top. An approximate scale bar and north arrow have added using distinctive features on each photograph with reference to a 1:1,000,000 scale navigation chart. Astronaut photographs provide a unique source of moderate resolution reef remote sensing data because of their global coverage and (immediate) availability in the public domain. The database of photographs can be searched an browsed online and high-resolution digital copies of photographs in this atlas can be accessed via the Website of Earth Science and Image Analysis at NASA's Johnson Space Center:

Reproductive ecology and early life history traits of the brooding coral, Porites astreoides, from shallow to mesophotic zones

NASA Astrophysics Data System (ADS)

Goodbody-Gringley, Gretchen; Wong, Kevin H.; Becker, Danielle M.; Glennon, Keegan; de Putron, Samantha J.

2018-06-01

Early life history traits of brooding corals are often affected by the environmental conditions experienced by parental colonies. Such parental effects can impact offspring survival, which influences the overall success of a population as well as resilience to environmental challenges. This study examines the reproductive ecology and early life history traits of the brooding coral Porites astreoides across a depth gradient in Bermuda. Fecundity, larval size, larval Symbiodinium density, and settlement success, as well as post-metamorphic juvenile survival, growth, and Symbiodinium density were compared across three reef sites representing an inshore patch reef (2-5 m), an offshore rim reef (8-10 m), and an upper-mesophotic reef (30-33 m). Although fecundity did not differ across sites, larvae produced by colonies on the patch reef site were smaller, had lower Symbiodinium densities, and had lower rates of settlement and juvenile survival compared to larvae from colonies on the rim and upper-mesophotic reef sites. Larvae produced by colonies from the rim and upper-mesophotic sites did not differ in size or Symbiodinium densities; however, rates of settlement, growth, and survival were higher for larvae from the upper-mesophotic site compared to those from the rim reef site. These results indicate that offspring quality and success vary among sites with differing environmental conditions and may imply higher recruitment potential and resilience for upper-mesophotic corals.

Characterizing the diversity of coral reef habitats and fish communities found in a UNESCO World Heritage Site: the strategy developed for Lagoons of New Caledonia.

PubMed

Andréfouët, S; Wantiez, L

2010-01-01

Since 1972, the UNESCO "World Heritage Convention" offers an international canvas for conservation and management that targets areas of high cultural and environmental significance. To support the designation of areas within the 36.000 km(2) of New Caledonia coral reefs and lagoons as a World Heritage Site, the natural value and diversity of the proposed zones needed to be demonstrated. To exhaustively identify each configuration of shallow habitats, high resolution remote sensing images were used to select the sampling sites. This optimal scheme resulted in the selection of nearly 1300 sampling sites, and was then simplified to render its application realistic. In the final sampling plan, only the most common or the most remarkable coral zones were selected. Following this selection, in situ habitat and fish surveys were conducted in 2006-2008 in five large areas spanning a 600 km-long latitudinal gradient. Habitats were described using line-intercept transects in parallel with underwater visual census of indicator and commercial coral reef fish species. We report here on the results achieved in terms of: (i) the actual diversity of coral habitats captured by the remote sensing based sampling strategy, (ii) the different reef fish communities captured from the different sites, and (iii) how well they represent New Caledonia diversity. We discuss the possible generalization of this scheme to other sites, in the context of World Heritage Site selection and for other large-scale conservation planning activities. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

Marine microbial communities of the Great Barrier Reef lagoon are influenced by riverine floodwaters and seasonal weather events.

PubMed

Angly, Florent E; Heath, Candice; Morgan, Thomas C; Tonin, Hemerson; Rich, Virginia; Schaffelke, Britta; Bourne, David G; Tyson, Gene W

2016-01-01

The role of microorganisms in maintaining coral reef health is increasingly recognized. Riverine floodwater containing herbicides and excess nutrients from fertilizers compromises water quality in the inshore Great Barrier Reef (GBR), with unknown consequences for planktonic marine microbial communities and thus coral reefs. In this baseline study, inshore GBR microbial communities were monitored along a 124 km long transect between 2011 and 2013 using 16S rRNA gene amplicon sequencing. Members of the bacterial orders Rickettsiales (e.g., Pelagibacteraceae) and Synechococcales (e.g., Prochlorococcus), and of the archaeal class Marine Group II were prevalent in all samples, exhibiting a clear seasonal dynamics. Microbial communities near the Tully river mouth included a mixture of taxa from offshore marine sites and from the river system. The environmental parameters collected could be summarized into four groups, represented by salinity, rainfall, temperature and water quality, that drove the composition of microbial communities. During the wet season, lower salinity and a lower water quality index resulting from higher river discharge corresponded to increases in riverine taxa at sites near the river mouth. Particularly large, transient changes in microbial community structure were seen during the extreme wet season 2010-11, and may be partially attributed to the effects of wind and waves, which resuspend sediments and homogenize the water column in shallow near-shore regions. This work shows that anthropogenic floodwaters and other environmental parameters work in conjunction to drive the spatial distribution of microorganisms in the GBR lagoon, as well as their seasonal and daily dynamics.

Marine microbial communities of the Great Barrier Reef lagoon are influenced by riverine floodwaters and seasonal weather events

PubMed Central

Heath, Candice; Morgan, Thomas C.; Tonin, Hemerson; Rich, Virginia; Schaffelke, Britta; Bourne, David G.; Tyson, Gene W.

2016-01-01

The role of microorganisms in maintaining coral reef health is increasingly recognized. Riverine floodwater containing herbicides and excess nutrients from fertilizers compromises water quality in the inshore Great Barrier Reef (GBR), with unknown consequences for planktonic marine microbial communities and thus coral reefs. In this baseline study, inshore GBR microbial communities were monitored along a 124 km long transect between 2011 and 2013 using 16S rRNA gene amplicon sequencing. Members of the bacterial orders Rickettsiales (e.g., Pelagibacteraceae) and Synechococcales (e.g., Prochlorococcus), and of the archaeal class Marine Group II were prevalent in all samples, exhibiting a clear seasonal dynamics. Microbial communities near the Tully river mouth included a mixture of taxa from offshore marine sites and from the river system. The environmental parameters collected could be summarized into four groups, represented by salinity, rainfall, temperature and water quality, that drove the composition of microbial communities. During the wet season, lower salinity and a lower water quality index resulting from higher river discharge corresponded to increases in riverine taxa at sites near the river mouth. Particularly large, transient changes in microbial community structure were seen during the extreme wet season 2010–11, and may be partially attributed to the effects of wind and waves, which resuspend sediments and homogenize the water column in shallow near-shore regions. This work shows that anthropogenic floodwaters and other environmental parameters work in conjunction to drive the spatial distribution of microorganisms in the GBR lagoon, as well as their seasonal and daily dynamics. PMID:26839738

Inter-habitat variation in density and size composition of reef fishes from the Cuban Northwestern shelf.

PubMed

Aguilar, Consuelo; González-Sansón, Gaspar; Cabrera, Yureidy; Ruiz, Alexei; Curry, R Allen

2014-06-01

Movement and exchange of individuals among habitats is critical for the dynamics and success of reef fish populations. Size segregation among habitats could be taken as evidence for habitat connectivity, and this would be a first step to formulate hypotheses about ontogenetic inter-habitat migrations. The primary goal of our research was to find evidence of inter-habitat differences in size distributions and density of reef fish species that can be classified a priori as habitat-shifters in an extensive (-600km2) Caribbean shelf area in NW Cuba. We sampled the fish assemblage of selected species using visual census (stationary and transect methods) in 20 stations (sites) located in mangrove roots, patch reefs, inner zone of the crest and fore reef (12-16m depth). In each site, we performed ten censuses for every habitat type in June and September 2009. A total of 11 507 individuals of 34 species were counted in a total of 400 censuses. We found significant differences in densities and size compositions among reef and mangrove habitats, supporting the species-specific use of coastal habitats. Adults were found in all habitats. Reef habitats, mainly patch reefs, seem to be most important for juvenile fish of most species. Mangroves were especially important for two species of snappers (Lutjanus apodus and L. griseus), providing habitat for juveniles. These species also displayed well defined gradients in length composition across the shelf.

The application of PIT tags to measure transport of detrital coral fragments on a fringing reef: Majuro Atoll, Marshall Islands

NASA Astrophysics Data System (ADS)

Ford, Murray R.

2014-06-01

Passive integrated transponder (PIT) tags are a radio-frequency identification device widely used as a machine-readable identification tool in fisheries research. PIT tags have also been employed, to a lesser extent, to track the movement of gravel-sized clasts within fluvial and coastal systems. In this study, PIT tags were inserted into detrital coral fragments and used to establish source-sink transport pathways on a fringing reef on Majuro Atoll in the Marshall Islands. Results suggest the transport of gravel-sized material on the inter-tidal reef flat is exclusively across-reef towards the lagoon. Considerable variation in the distance travelled by fragments was observed. Fragments were largely intact and visually recognisable after almost 5 months on the reef flat. However, the branches of some recovered fragments had broken off and corallite abrasion was observed in recovered fragments. This study indicates that PIT tags are an inexpensive and powerful new addition to the suite of sediment transport and taphonomic tools for researchers working within coral reef systems.

Coral reef grazer-benthos dynamics complicated by invasive algae in a small marine reserve

PubMed Central

Stamoulis, Kostantinos A.; Friedlander, Alan M.; Meyer, Carl G.; Fernandez-Silva, Iria; Toonen, Robert J.

2017-01-01

Blooms of alien invasive marine algae have become common, greatly altering the health and stability of nearshore marine ecosystems. Concurrently, herbivorous fishes have been severely overfished in many locations worldwide, contributing to increases in macroalgal cover. We used a multi-pronged, interdisciplinary approach to test if higher biomass of herbivorous fishes inside a no-take marine reserve makes this area more resistant to invasive algal overgrowth. Over a two year time period, we (1) compared fish biomass and algal cover between two fished and one unfished patch reef in Hawai’i, (2) used acoustic telemetry to determine fidelity of herbivorous fishes to the unfished reef, and (3) used metabarcoding and next-generation sequencing to determine diet composition of herbivorous fishes. Herbivore fish biomass was significantly higher in the marine reserve compared to adjacent fished reefs, whereas invasive algal cover differed by species. Herbivorous fish movements were largely confined to the unfished patch reef where they were captured. Diet analysis indicated that the consumption of invasive algae varied among fish species, with a high prevalence of comparatively rare native algal species. Together these findings demonstrate that the contribution of herbivores to coral reef resilience, via resistance to invasive algae invasion, is complex and species-specific. PMID:28276458

Burdigalian turbid water patch reef environment revealed by larger benthic foraminifera

NASA Astrophysics Data System (ADS)

Novak, V.; Renema, W.; Throughflow-project

2012-04-01

Ancient isolated patch reefs outcropping from siliciclastic sediments are a trademark for the Miocene carbonate deposits occurring in East Kalimantan, Indonesia. They develop in transitional shelf sediments deposited between deltaic and deep marine deposits (Allen and Chambers, 1998). The Batu Putih Limestone (Wilson, 2005) and similar outcrops in adjacent areas have been characterized as shallow water carbonates influenced by high siliciclastic input, showing low relief patch reefs in turbid waters. Larger benthic foraminifera (LBF) are excellent markers for biochronology and paleoenvironmental reconstruction. This study aims to reveal age and paleoenvironment of a shallow water carbonate patch reef developed in mixed depositional system by using LBF and microfacies analysis. The studied section is located near Bontang, East Kalimantan, and is approximately 80 m long and 12 m high. It is placed within Miocene sediments in the central part of the Kutai Basin. Patch reef and capping sediments were logged through eight transects along section and divided into nine different lithological units from which samples were collected. Thin sections and isolated specimens of larger benthic foraminifera were analyzed and recognized to species level (where possible) providing age and environmental information. Microfacies analysis of thin sections included carbonate classification (textural scheme of Dunham, 1962) and assemblage composition of LBF, algae and corals relative abundance. Three environmentally indicative groups of LBF were separated based on test morphology, habitat or living relatives (Hallock and Glenn, 1986). Analysed foraminifera assemblage suggests Burdigalian age (Tf1). With use of microfacies analysis nine successive lithological units were grouped into five facies types. Paleoenvironmental reconstruction of LBF fossil assemblage indicate two cycles of possible deepening recorded in the section. Based on high muddy matrix ratio in analyzed thin-sections we still cannot conclude whether they were deeper water assemblage, or that they occurred in shallower water and influenced by turbid conditions as the result of terrigenous input. According to preliminary analysis and siliciclastic content in the sediments the later one should be more likely. Further work will include additional fossil groups analysis (corals, algae and bryozoans), detailed petrographical analysis and Strontium isotope stratigraphy. Allen, G.P., and Chambers, J.L.C. (1998): Sedimentation in the Modern and Miocene Mahakam Delta. Indonesian Petroleum Association, Jakarta, Indonesia, 236 p. Dunham, R.J. (1962): Classification of carbonate rocks according to their depositional texture. In: Ham, W.E., ed., Classification of Carbonate Rocks: American Association of Petroleum Geologists Memoir, v. 1, p. 108-121. Hallock, P. and Glenn, C.E. (1986): Larger Foraminifera: A tool for paleoenvironmental analysis of Cenozoic carbonate depositional facies. Palaios 1, 55-64. Wilson, M.E.J. (2005): Development of equatorial delta-front patch reefs during the Neogene, Borneo. - Journal of Sedimentary Research, 75(1): 114-133.

Environmental controls on spatial patterns in the long-term persistence of giant kelp in central California

USGS Publications Warehouse

Young, Mary Alida; Cavanaugh, Kyle C.; Bell, Tom W.; Raimondi, Peter T.; Edwards, Christopher A.; Drake, Patrick T.; Erikson, Li H.; Storlazzi, Curt

2016-01-01

As marine management is moving towards the practice of protecting static areas, it is 44 important to make sure protected areas capture and protect persistent populations. Rocky reefs in 45 many temperate areas worldwide serve as habitat for canopy forming macroalgae and these 46 structure forming species of kelps (order Laminariales) often serve as important habitat for a great 47 diversity of species. Macrocystis pyrifera is the most common canopy forming kelp species found 48 along the coast of California but the distribution and abundance of M. pyrifera varies in space and 49 time. The purpose of this study is to determine what environmental parameters are correlated with 50 the spatial and temporal persistence of M. pyrifera along the central coast of California and how 51 well those environmental parameters can be used to predict areas where M. pyrifera is more likely 52 to persist. Nine environmental variables considered in this study included depth of the seafloor, 53 structure of the rocky reef, proportion of rocky reef, size of kelp patch, biomass of kelp within a 54 patch, distance from the edge of a kelp patch, sea surface temperature, wave orbital velocities, and 55 population connectivity of individual kelp patches. Using a generalized linear mixed effects model 56 (GLMM), the persistence of M. pyrifera was significantly associated with seven of the nine 57 variables considered: depth, complexity of the rocky reef, proportion of rock, patch biomass, 58 distance from the edge of a patch, population connectivity, and wave-orbital velocities. These 59 seven environmental variables were then used to predict the persistence of kelp across the central 60 coast and these predictions were compared to a reserved dataset of M. pyrifera persistence, which 61 was not used in the creation of the GLMM. The environmental variables were shown to accurately 62 predict the persistence of M. pyrifera within the central coast of California (r = 0.71, P<0.001). 63 Because persistence of giant kelp is important to the community structure of kelp forests, 64 understanding those factors that support persistent populations of M. pyrifera will enable more 65 effective management of these ecosystems.

KSC-03pd1387

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - A team aboard the Liberty Star secures lines to underwater research equipment being used on an expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. The equipment includes an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

Cape Baleia, Caravelas, Brazil

NASA Image and Video Library

1993-01-19

STS054-86-001 (13-19 Jan. 1993) --- This 70mm view shows a spectacular multiple spit on the coast of Brazil, about halfway between Rio de Janeiro and the mouth of the Amazon River. Over a few thousand years, according to NASA scientists, shifting regimes of wave and current patterns piled up sand onto a series of beach ridges and tidal lagoons. The present swirls of sediment along the coast evidently were derived from beach erosion, because streams flowing into the Atlantic contain dark, clear water. Offshore, reefs and sandbanks parallel the coast. The largest is the Recife da Pedra Grande (Big Rocks Reef).

Mid-Pacific Marine Laboratory. Annual report for the period, 1 October 1977--30 September 1978

DOE Office of Scientific and Technical Information (OSTI.GOV)

Reese, E.S.; Johnson, V.R. Jr.

1979-03-01

Studies on behavior included reproduction and sociobiology of reef fishes and aggression, hearing, and ultrasonic telemetry in sharks. Ecological studies included population, growth, and mortality studies on birds, corals, crustacea, echinoderms, fishes, molluscs, and rats. Geochemistry studies included biogeochemistry of reef organisms and hydrogeochemistry of groundwater. Geology studies included bioerosion of sea urchins, biology of endolithic processes, and survey of soils. Oceanography studies were conducted on lagoon circulation. Physiological studies were conducted on symbiosis in corals and utilization of organic material by Foraminifera. Studies on systematics of algae, echinoderms, and fishes were conducted. (HLW)

Survivorship and feeding preferences among size classes of outplanted sea urchins, Tripneustes gratilla, and possible use as biocontrol for invasive alien algae

PubMed Central

Ringang, Rory R.; Cantero, Sean Michael A.; Toonen, Robert J.

2015-01-01

We investigate the survivorship, growth and diet preferences of hatchery-raised juvenile urchins, Tripneustes gratilla, to evaluate the efficacy of their use as biocontrol agents in the efforts to reduce alien invasive algae. In flow-through tanks, we measured urchin growth rates, feeding rates and feeding preferences among diets of the most common invasive algae found in Kāneʻohe Bay, Hawaiʻi: Acanthophora spicifera, Gracilaria salicornia, Eucheuma denticulatum and Kappaphycus clade B. Post-transport survivorship of outplanted urchins was measured in paired open and closed cages in three different reef environments (lagoon, reef flat and reef slope) for a month. Survivorship in closed cages was highest on the reef flat (∼75%), and intermediate in the lagoon and reef slope (∼50%). In contrast, open cages showed similar survivorship on the reef flat and in the lagoon, but only 20% of juvenile urchins survived in open cages placed on the reef slope. Urchins grew significantly faster on diets of G. salicornia (1.58 mm/week ± 0.14 SE) and Kappaphycus clade B (1.69 ± 0.14 mm/wk) than on E. denticulatum (0.97 ± 0.14 mm/wk), with intermediate growth when fed on A. spicifera (1.23 ± 0.11 mm/wk). Interestingly, urchins display size-specific feeding preferences. In non-choice feeding trials, small urchins (17.5–22.5 mm test diameter) consumed G. salicornia fastest (6.08 g/day ± 0.19 SE), with A. spicifera (4.25 ± 0.02 g/day) and Kappaphycus clade B (3.83 ± 0.02 g/day) intermediate, and E. denticulatum was clearly the least consumed (2.32 ± 0.37 g/day). Medium-sized (29.8–43.8 mm) urchins likewise preferentially consumed G. salicornia (12.60 ± 0.08 g/day), with less clear differences among the other species in which E. denticulatum was still consumed least (9.35 ± 0.90 g/day). In contrast, large urchins (45.0–65.0 mm) showed no significant preferences among the different algae species at all (12.43–15.24 g/day). Overall consumption rates in non-choice trials were roughly equal to those in the choice trials, but differences among feeding rates on each species were not predictive of feeding preferences when urchins were presented all four species simultaneously. In the choice feeding trials, both small and medium urchins clearly preferred A. spicifera over all other algae (roughly twice as much consumed as any other species). Again, however, differences were less pronounced among adult urchins, with adults showing a significant preference for A. spicifera and Kappaphycus clade B compared to the other two algal species. These findings indicate that outplanted urchins are surviving on the reef flats and eating a variety of alien invasive algae as intended. Although juvenile urchins show stronger feeding preferences, these animals grow quickly, and adult urchins are more generalist herbivores that consume all four alien invasive algae. PMID:26401450

Biogeochemistry of Mariana Islands coastal sediments: terrestrial influence on /gd13, Ash, CaCO3, Al, Fe, Si and P

NASA Astrophysics Data System (ADS)

Matson, Ernest A.

1989-01-01

Stable C isotope ratios (δ13C-PDB), percentages of organic matter, and HCl insoluble ash and soluble carbonates, extractable Fe, Al, Si and P were used to determine the distribution and accumulation of terrestrial material in reef-flat moats and lagoons of two high islands (Guam and Saipan) in the western tropical Pacific. Carbonate sediments of a reef-flat moat infiltrated by seepage of aquifer waters (but without surface runoff) were depleted in both P (by 38%) and 13C (by 41%) and enriched in Si (by 100%) relative to offshore lagoon sediments. Iron and ash accumulated in depositional regimes regardless of the occurrence of runoff but was depleted from coarse-grained carbonates in turbulent regimes. Aluminum (>ca. 10 to 20 μmol g-1), Fe (>ca. 1 to 3 μmol g-1) and ash (>0.5%) indicated terrigenous influence which was corroborated by depletions in both 13C and P. Low-salinity geochemical segregation, natural biochemical accumulation, as well as long-shore currents and eddies help sequester these materials nearshore.

Wave Dissipation on Low- to Super-Energy Coral Reefs

NASA Astrophysics Data System (ADS)

Harris, D. L.

2016-02-01

Coral reefs are valuable, complex and bio-diverse ecosystems and are also known to be one of the most effective barriers to swell events in coastal environments. Previous research has found coral reefs to be remarkably efficient in removing most of the wave energy during the initial breaking and transformation on the reef flats. The rate of dissipation is so rapid that coral reefs have been referred to as rougher than any known coastal barrier. The dissipation of wave energy across reef flats is crucial in maintaining the relatively low-energy conditions in the back reef and lagoonal environments providing vital protection to adjacent beach or coastal regions from cyclone and storm events. A shift in the regulation of wave energy by reef flats could have catastrophic consequences ecologically, socially, and economically. This study examined the dissipation of wave energy during two swell events in Tahiti and Moorea, French Polyesia. Field sites were chosen in varying degrees of exposure and geomorphology from low-energy protected sites (Tiahura, Moorea) to super-energy sites (Teahupo'o, Tahiti). Waves were measured during two moderate to large swell events in cross reef transects using short-term high-resolution pressure transducers. Wave conditions were found to be similar in all back reef locations despite the very different wave exposure at each reef site. However, wave conditions on the reef flats were different and mirrored the variation in wave exposure with depth over the reef flat the primary regulator of reef flat wave height. These results indicate that coral reef flats evolve morphodynamically with the wave climate, which creates coral reef geomorphologies capable of dissipating wave energy that results in similar back reef wave conditions regardless of the offshore wave climate.

Predation and landscape characteristics independently affect reef fish community organization.

PubMed

Stier, Adrian C; Hanson, Katharine M; Holbrook, Sally J; Schmitt, Russell J; Brooks, Andrew J

2014-05-01

Trophic island biogeography theory predicts that the effects of predators on prey diversity are context dependent in heterogeneous landscapes. Specifically, models predict that the positive effect of habitat area on prey diversity should decline in the presence of predators, and that predators should modify the partitioning of alpha and beta diversity across patchy landscapes. However, experimental tests of the predicted context dependency in top-down control remain limited. Using a factorial field experiment we quantify the effects of a focal predatory fish species (grouper) and habitat characteristics (patch size, fragmentation) on the partitioning of diversity and assembly of coral reef fish communities. We found independent effects of groupers and patch characteristics on prey communities. Groupers reduced prey abundance by 50% and gamma diversity by 45%, with a disproportionate removal of rare species relative to common species (64% and 36% reduction, respectively; an oddity effect). Further, there was a 77% reduction in beta diversity. Null model analysis demonstrated that groupers increased the importance of stochastic community assembly relative to patches without groupers. With regard to patch size, larger patches contained more fishes, but a doubling of patch size led to a modest (36%) increase in prey abundance. Patch size had no effect on prey diversity; however, fragmented patches had 50% higher species richness and modified species composition relative to unfragmented patches. Our findings suggest two different pathways (i.e., habitat or predator shifts) by which natural and/or anthropogenic processes can drive variation in fish biodiversity and community assembly.

Coral reefs as buffers during the 2009 South Pacific tsunami, Upolu Island, Samoa

NASA Astrophysics Data System (ADS)

McAdoo, Brian G.; Ah-Leong, Joyce Samuelu; Bell, Lui; Ifopo, Pulea; Ward, Juney; Lovell, Edward; Skelton, Posa

2011-07-01

The coral reef bordering the coastline of Samoa affected by the 29 September 2009 tsunami provides a variety of ecosystem services — from nurseries for fisheries and inshore source of food for local communities, to aesthetics for tourists, and the width of the lagoon may have been a factor in reducing the onshore wave height. To understand the complex interactions between the onshore human population and the offshore coral, we formed an interdisciplinary survey team to document the effects the tsunami had on the nearshore coral reef, and how these changes might affect local inhabitants. The scale of reef damage varied from severe, where piles of freshly-killed coral fragments and mortality were present, to areas that exhibited little impact, despite being overrun by the tsunami. We found that many coral colonies were impacted by tsunami-entrained coral debris, which had been ripped up and deposited on the fore reef by repeated cyclones and storm waves. In other places, large surface area tabular coral sustained damage as the tsunami velocity increased as it was funneled through channels. Areas that lacked debris entrained by the waves as well as areas in the lee of islands came through relatively unscathed, with the exception of the delicate corals that lived on a sandy substrate. In the lagoon on the south coast with its steep topography, coral colonies were damaged by tsunami-generated debris from onshore entrained in the backwash. Despite the potential for severe tsunami-related damage, there were no noticeable decreases in live coral cover between successive surveys at two locations, although algal cover was higher with the increased nutrients mobilized by the tsunami. While there was an immediate decrease in fish takes in the month following the tsunami, when supporting services were likely impacted, both volume and income have rapidly increased to pre-tsunami levels. Long-term monitoring should be implemented to determine if nursery services were affected.

Selective predation for low body condition at the larval-juvenile transition of a coral reef fish.

PubMed

Hoey, Andrew S; McCormick, Mark I

2004-03-01

Mortality is known to be high during the transition from larval to juvenile life stages in organisms that have complex life histories. We are only just beginning to understand the processes that influence which individuals survive this period of high mortality, and which traits may be beneficial. Here we document a field experiment that examines the selectivity of predation immediately following settlement to the juvenile population in a common tropical fish, Pomacentrus amboinensis (Pomacentridae). Newly metamorphosed fish were tagged and randomly placed onto replicated patches of natural habitat cleared of resident fishes. After exposure to transient predators for 3 days, fish were recollected and the attributes of survivors from patch reefs that sustained high mortality were compared to individuals from patch reefs that experienced low mortality. Seven characteristics of individuals, which were indicative of previous and present body condition, were compared between groups. Predation was found to be selective for fish that grew slowly in the latter third of their larval phase, were low in total lipids, and had a high standardized weight (Fulton's K). Traits developed in the larval phase can strongly influence the survival of individuals over this critical transition period for organisms with complex life cycles.

Guidebook to the Gaudalupian symposium

USGS Publications Warehouse

Rohr, D.M.; Wardlaw, B.R.; Rudine, S.F.; Haneef, Mohammad; Hall, A.J.; Grant, R.E.

2000-01-01

Compared to the Guadalupe Mountains of Texas and New Mexico the depositional environments of the Permian strata of the Glass Mountains (and adjacent Del Norte Mountains) are less well known. In general, the Guadalupian facies in the the Glass and Del Norte mountains changes from predominantly carbonate facies in the northeast to thicker clastic facies in the southwest. Philip B. Kind (1931) originally considered this trend to reflect an uplifted clastic source to the southwest, with carbonate facies developing away from the source area. Ross (1986) interpreted the eastern portion of the Road Canyon and Word formations to consist the shelf, shelf-edge bioherm, and reef facies, and the southwest area to consist of deeper water siliceous shale, clastic limestone, and basinal sandstone facies. Probably the best known controversy in the Glass Mountains involves the depositional environment of the Skinner Ranch Formation (Leonardian according to Ross, 1986; Wolfcampian according to Cooper and Grant, 1972) at its type section on Leonard Mountain. Cooper and Grant (1964) identified in situ patch reefs at the base of the section, which were subsequently interpreted as displaced limestone blocks deposited in a slope environment (Rogers, 1972; Cys and Mazzullo, 1978; Ross, 1986). Later Flores, McMillan, and Watters (1977) interpreted the same units as subtidal and intertidal deposits. The Skinner Ranch Formation illustrates the complexities involved in interpreting the paleogeography of the Glass Mountains. If the Sinner Ranch contains displaced blocks, some eroded from older units, it explains the occurrence of Wolfcampian fossils in the Skinner Ranch (Ross, 1986).The slop facies interpretation also is used to place the shelf edge at that time between Skinner Ranch outcrops at Leonard Mountain and the lagoonal, backreef deposits of the Hess Formation to the east, although most of the actual shelf edge is not preserved (Ross, 1987:30). Similar conflicting interpretations exist in younger rocks in the western facies of the Leonardian Guadalupian to the southwest in the Del Norte Mountains. Ross (1986, 1987) considered the western facies of the Road Canyon and Word formations to be basinal shales and turbidites. Wardlaw et al. (1990) and Rohr et al. (1987) have interpreted this area to be shallow intertidal to lagoonal environments adjacent to an uplifted area to the south. The type section of the Road Canyon Formation is also a subject of disagreement and will be discusses in more detail later.

Selective feeding by coral reef fishes on coral lesions associated with brown band and black band disease

NASA Astrophysics Data System (ADS)

Chong-Seng, K. M.; Cole, A. J.; Pratchett, M. S.; Willis, B. L.

2011-06-01

Recent studies have suggested that corallivorous fishes may be vectors for coral disease, but the extent to which fishes actually feed on and thereby potentially transmit coral pathogens is largely unknown. For this study, in situ video observations were used to assess the level to which fishes fed on diseased coral tissues at Lizard Island, northern Great Barrier Reef. Surveys conducted at multiple locations around Lizard Island revealed that coral disease prevalence, especially of brown band disease (BrB), was higher in lagoon and backreef locations than in exposed reef crests. Accordingly, video cameras were deployed in lagoon and backreef habitats to record feeding by fishes during 1-h periods on diseased sections of each of 44 different coral colonies. Twenty-five species from five fish families (Blennidae, Chaetodontidae, Gobiidae, Labridae and Pomacentridae) were observed to feed on infected coral tissues of staghorn species of Acropora that were naturally infected with black band disease (BBD) or brown band disease (BrB). Collectively, these fishes took an average of 18.6 (±5.6 SE) and 14.3 (±6.1 SE) bites per hour from BBD and BrB lesions, respectively. More than 40% (408/948 bites) and nearly 25% (314/1319 bites) of bites were observed on lesions associated with BBD and BrB, respectively, despite these bands each representing only about 1% of the substratum available. Moreover, many corallivorous fishes ( Labrichthys unilineatus, Chaetodon aureofasciatus, C. baronessa, C. lunulatus, C. trifascialis, Cheiloprion labiatus) selectively targeted disease lesions over adjacent healthy coral tissues. These findings highlight the important role that reef fishes may play in the dynamics of coral diseases, either as vectors for the spread of coral disease or in reducing coral disease progression through intensive and selective consumption of diseased coral tissues.

Temporal shifts in reef lagoon sediment composition, Discovery Bay, Jamaica

NASA Astrophysics Data System (ADS)

Perry, Christopher T.; Taylor, Kevin G.; Machent, Philip G.

2006-03-01

Discovery Bay, north Jamaica, forms a large (1.5 km wide), deep (up to 56 m) embayment that acts as a sink for reef-derived and lagoonal carbonate sediments. Since the mid-1960s, the bay has also provided a sink for inputs of bauxite sediment that are spilled during loading at a boat terminal constructed within Discovery Bay. Bauxite has accumulated across much of the southern section of the bay with surficial sediments presently composed of up to 35 weight% non-carbonate. Cores recovered from sites on the western side of the bay provide a stratigraphic record of this history of bauxite contamination across water depths from 5 to 25 m. The bauxite-influenced upper sediment horizons are clearly visible in each core from the distinctive red-brown colouration of the sediment. These sediments are composed of approximately 10% non-carbonate (bauxite) and have Fe contents of around 2-3000 μg/g (up to 7000 μg/g). The thickness of this upper bauxite-contaminated sequence increases down transect (approximately 18 cm in the shallowest core, to around 47 cm in the deepest core), and in each core overlies a sequence of 'clean' lagoon carbonates. These typically are poorly sorted carbonate sands with variable amounts of coral rubble. Down-core data on CaCO 3 and Fe content provide a chemical record of decreasing sediment contamination with depth, with the lower 'clean' carbonates composed of only around 2% non-carbonate and <700 μg/g Fe. Down-core sediment-constituent data also indicate significant changes in sediment production at the shallowest sites. At depths of 5 and 10 m, sediment assemblages have shifted from diverse assemblages of coral, mollusc, Amphiroa and Halimeda in the clean lagoon sands, to assemblages dominated by Halimeda and Amphiroa within the surficial sediments. At the deeper sites, no major down-core shifts in sediment constituents occur. These sites thus record a rather complex history of changes in sediment composition and chemistry. Clear shifts in chemistry and stratigraphy occur in all the cores and reflect progressive bauxite contamination in the near-surface horizons. These inputs, however, do not appear to have directly affected carbonate production, since the major constituent changes appear to be a response to more regional declines in coral community and reef status.

Chemistry of modern sediments in a hypersaline lagoon, north of Jeddah, Red Sea

NASA Astrophysics Data System (ADS)

El-Sayed, Mahmoud Kh.

1987-10-01

Previous studies of modern peritidal sedimentary environments of the Red Sea, such as hypersaline lagoons and sea-marginal flats, have concentrated on its northern part, particularly in the Gulf of Aqaba. However, little is known about lagoon sediments in other localities along the Red Sea coastal stretches. This paper deals with the chemical characteristics of the sediments of a hypersaline (Ras Hatiba) lagoon, north of Jeddah, Saudi Arabia. The chemistry of hypersaline lagoon sediments is considerably changed following the modifications to the water chemistry by evaporation and precipitation. Ras Hatiba lagoon is a hypersaline elongated water body connected to the Red Sea by a narrow and shallow opening. The total area of the lagoon is c. 30 km 2. Coarse bioclastic sands are dominant in the lagoon and mostly surround lithified calcareous grounds. However, fine silt and clay sediments are present in separate patches. The sediments are rich in carbonates (average 78·5%) and organic carbon (average 7·3%), although they are negatively correlated. Calcium (average 25·1%) and magnesium (average 10·8‰) show a similar distribution pattern in the lagoon sediments. Strontium (average 5·2‰) is positively correlated with calcium. Sodium and potassium are relatively highly concentrated in the sediments (average 118 ppm and 173 ppm, respectively). Magnesium and strontium are of prime importance in the process of mineralization and diagenesis. The sabkha formation surrounding the lagoon is of low carbonate and organic carbon content, compared with the lagoon sediments, whilst it is characterized by high magnesium, sodium and potassium concentrations. Ras Hatiba lagoon sediments and sabkha resemble those of the northern Red Sea in the Gulfs of Aqaba and Suez and the Arabian Gulf in their major sedimentological and chemical characteristics.

Ecosystem Services of Coastal Habitats and Fisheries: Multi-Scale Ecological and Economic Modeling

EPA Science Inventory

Critical habitats for fish and wildlife often are small patches in landscapes, e.g., aquatic vegetation beds, reefs, isolated ponds and wetlands, remnant old growth forests, etc, yet the same animal populations that depend on these patches for reproduction or survival can be exte...

Keeping up with sea-level rise: Carbonate production rates in Palau and Yap, western Pacific Ocean.

PubMed

van Woesik, Robert; Cacciapaglia, Christopher William

2018-01-01

Coral reefs protect islands from tropical storm waves and provide goods and services for millions of islanders worldwide. Yet it is unknown how coral reefs in general, and carbonate production in particular, will respond to sea-level rise and thermal stress associated with climate change. This study compared the reef-building capacity of different shallow-water habitats at twenty-four sites on each of two islands, Palau and Yap, in the western Pacific Ocean. We were particularly interested in estimating the inverse problem of calculating the value of live coral cover at which net carbonate production becomes negative, and whether that value varied across habitats. Net carbonate production varied among habitats, averaging 10.2 kg CaCO3 m-2 y-1 for outer reefs, 12.7 kg CaCO3 m-2 y-1 for patch reefs, and 7.2 kg CaCO3 m-2 y-1 for inner reefs. The value of live coral cover at which net carbonate production became negative varied across habitats, with highest values on inner reefs. These results suggest that some inner reefs tend to produce less carbonate, and therefore need higher coral cover to produce enough carbonate to keep up with sea-level rise than outer and patch reefs. These results also suggest that inner reefs are more vulnerable to sea-level rise than other habitats, which stresses the need for effective land-use practices as the climate continues to change. Averaging across all reef habitats, the rate of carbonate production was 9.7 kg CaCO3 m-2 y-1, or approximately 7.9 mm y-1 of potential vertical accretion. Such rates of vertical accretion are higher than projected averages of sea-level rise for the representative concentration pathway (RCP) climate-change scenarios 2.6, 4.5, and 6, but lower than for the RCP scenario 8.5.

Mesophotic bioerosion: Variability and structural impact on U.S. Virgin Island deep reefs

NASA Astrophysics Data System (ADS)

Weinstein, David K.; Smith, Tyler B.; Klaus, James S.

2014-10-01

Mesophotic reef corals, found 30-150 m below sea level, build complex structures that provide habitats for diverse ecosystems. Whereas bioerosion is known to impact the development and persistence of shallow reef structures, little is known regarding the extent of mesophotic bioerosion or how it might affect deeper reef geomorphology and carbonate accretion. Originally pristine experimental coral substrates and collected coral rubble were both used to investigate the variation and significance of mesophotic coral reef bioerosion south of St. Thomas, U.S. Virgin Islands. Bioerosion rates were calculated from experimental coral substrates exposed as framework for 1 and 2 years at four structurally distinct mesophotic coral reef habitats (between 30 and 45 m) as well as at a mid-shelf patch reef (21 m) and a shallow fringing patch reef (9 m). The long-term effects of macroboring were assessed by examining coral rubble collected at all sites. Overall, differences in bioerosional processes were found between shallow and mesophotic reefs. Increases in bioerosion on experimental substrates (amount of weight lost) were related to both decreasing seawater depth and increasing biomass of bioeroding parrotfish. Significant differences in coral skeleton bioerosion rates were also found between the transitional mesophotic reef zone (30-35 m) and the upper mesophotic reef zone (35-50 m) after 2 years of exposure, ranging from - 19.6 to 3.7 g/year. Total coral rubble macroboring was greater at most deep sites compared to shallower sites. Bioerosional grazing was found to dominate initial substrate modification in reefs 30.7 m and shallower, but sponges are believed to act as the main time-averaged long-term substrate bioeroders in reefs between 35 and 50 m. Although initial substrate bioerosion rates of a uniform substrate were relatively homogeneous in the 35-50 m depth zone, comparison of site composition suggests that mesophotic bioerosion will vary depending on the amount, location, and type of available substrate, and the duration both coral rubble and in situ coral framework are exposed on the seafloor. These variations may exaggerate pronounced structural differences in mesophotic reef habitats that experience few other methods of erosion.

Seascape and life-history traits do not predict self-recruitment in a coral reef fish.

PubMed

Herrera, Marcela; Nanninga, Gerrit B; Planes, Serge; Jones, Geoffrey P; Thorrold, Simon R; Saenz-Agudelo, Pablo; Almany, Glenn R; Berumen, Michael L

2016-08-01

The persistence and resilience of many coral reef species are dependent on rates of connectivity among sub-populations. However, despite increasing research efforts, the spatial scale of larval dispersal remains unpredictable for most marine metapopulations. Here, we assess patterns of larval dispersal in the angelfish Centropyge bicolor in Kimbe Bay, Papua New Guinea, using parentage and sibling reconstruction analyses based on 23 microsatellite DNA loci. We found that, contrary to previous findings in this system, self-recruitment (SR) was virtually absent at both the reef (0.4-0.5% at 0.15 km(2)) and the lagoon scale (0.6-0.8% at approx. 700 km(2)). While approximately 25% of the collected juveniles were identified as potential siblings, the majority of sibling pairs were sampled from separate reefs. Integrating our findings with earlier research from the same system suggests that geographical setting and life-history traits alone are not suitable predictors of SR and that high levels of localized recruitment are not universal in coral reef fishes. © 2016 The Authors.

Reply to: Terry, J. and Goff, J. comment on “Late Cenozoic sea level and the rise of modern rimmed atolls” by Toomey et al. (2016), Palaeogeography, Palaeoclimatology, Palaeoecology 4 51: 73–83.

USGS Publications Warehouse

Toomey, Michael; Ashton, Andrew; Raymo, Maureen E.; Perron, J. Taylor

2017-01-01

We appreciate Terry and Goff's thoughtful comment in response to our proposed atoll development model. Flank collapse of reef-built slopes likely does affect plan-form atoll morphology in some locations and potentially poses a tsunami hazard to low-lying Pacific islands (Terry and Goff, 2013). However, given the often rapid rates of lagoon infill (> 1 mm/yr; Montaggioni, 2005), such failure events would likely need to be frequent and widespread in order to leave a morphologic imprint on modern western Pacific atoll lagoon depths. Few atoll flank collapse features have been dated but many of the arcuate bight-like structures (ABLS) identified could be inherited from scars incised into the initial volcanic edifice (e.g. Terry and Goff, 2013 and refs. therein) — submarine mass wasting has been extensively documented on young hotspot islands (e.g. Hawaiian Islands: Moore et al., 1989; Reunion: Oehler et al., 2008). Atolls in the Marshall Islands, where our main study site Enewetak Atoll is located, are likely ~ 50–100 million years old (Larson et al., 1995) and dating of adjacent deep-water turbidite aprons in the Nauru Basin (DSDP Site 462; Schlanger and Silva, 1986) suggests that large atoll flank collapse events have been relatively infrequent there since the mid-Miocene (< 11 Ma). In our simple, 1D atoll development model (Toomey et al., 2016a), we included the minimum set of processes (vertical accretion, dissolution, and lagoonal infilling) required to accurately simulate Enewetak's ‘recent’ depositional history (8.5–0 Ma) and explain basic differences in lagoon depth among western Pacific atolls.We agree future development of a model incorporating the wider range of processes impacting connectivity between reef-bound lagoons and the ocean (e.g. Ouillon et al., 2004; Toomey et al., 2016b), including stochastic mass wasting events, will be essential for exploring the plan-form and 3D shapes of atolls. To our knowledge, no quantitative model of long-term atoll development has explicitly linked lagoon restriction/sedimentation to episodic flank collapse events (e.g. Montaggioni et al., 2015; Paterson et al., 2006; Quinn, 1991; Warrlich et al., 2002). Testing Terry and Goff's proposed conceptual model for how rim failure processes affect atoll morphology in a numerical context will require deep drilling along arcuate bight-like structures, as well as adjacent, unaffected, rim and lagoon areas, in order quantify how often failures occur and how quickly the rim/lagoon is rebuilt afterwards. The model we present here provides a general framework capable of integrating atoll flank collapse processes once they are sufficiently constrained by such observational datasets.

Topographic control and accumulation rate of some Holocene coral reefs: south Florida and Dry Tortugas

USGS Publications Warehouse

Shinn, E.A.; Hudson, J.H.; Halley, R.B.; Lidz, B.H.; Taylor, D.L.

1977-01-01

Core drilling and examination of underwater excavation on 6 reef sites in south Florida and Dry Tortugas revealed that underlying topography is the major factor controlling reef morphology. Carbon-14 dating on coral recovered from cores enables calculation of accumulation rates. Accumulation rates were found to range from 0.38 m/1000 years in thin Holocene reefs to as much as 4.85 m/1000 years in thicker buildups. Cementation and alteration of corals were found to be more pronounced in areas of low buildup rates than in areas of rapid accumulation rates. Acropora palmata, generally considered the major reef builder in Florida, was found to be absent in most reefs drilled. At Dry Tortugas, the more than 13-meter thick Holocene reef did not contain A. palmata. The principal reef builders in this outer reef are the same as those which built the Pleistocene Key Largo formation, long considered to be fossilized patch reef complex.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hurst, J.M.; Lapointe, P.A.; Nyein, U.K.

Three Oligocene-Miocene carbonate depositional morphologies commonly occur: shoals, reefs, and isolated platforms. Lenticular shoals (0-25 m thick, 1 km long) are stacked and intercalated with siliciclastic mudstones. Facies include trough/festoon cross-bedded benthic foram grainstones passing laterally and vertically into red-algal dominated graded-laminated beds, bioturbated silty calcareous mudstone, and siliciclastic sandy foram wackestone and packstone. The morphology and facies are hydrodynamically controlled. Pinnacle reefs (1-2 km[sup 2]) dominated by red-algae, branching corals, and large mollusks occur on structure or aligned within shelf mudstones. The latter location reflects low sedimentation rates and hydrodynamic control. Isolated platforms (up to 150 km[sup 2]) aremore » environmental mosaics of marginal path reefs and shoals, interior lagoons, and islands plus marginal slopes. Facies are similar to shoals and reefs except there are more muddy fabrics and less high-energy facies. They develop on tilted fault blocks or eroded submerged arcs in the offshore Gulf of Martaban, distal to the ancestral Irrawaddy delta.« less

Human impacts on large benthic foraminifers near a densely populated area of Majuro Atoll, Marshall Islands.

PubMed

Osawa, Yoko; Fujita, Kazuhiko; Umezawa, Yu; Kayanne, Hajime; Ide, Yoichi; Nagaoka, Tatsutoshi; Miyajima, Toshihiro; Yamano, Hiroya

2010-08-01

Human impacts on sand-producing, large benthic foraminifers were investigated on ocean reef flats at the northeast Majuro Atoll, Marshall Islands, along a human population gradient. The densities of dominant foraminifers Calcarina and Amphistegina declined with distance from densely populated islands. Macrophyte composition on ocean reef flats differed between locations near sparsely or densely populated islands. Nutrient concentrations in reef-flat seawater and groundwater were high near or on densely populated islands. delta(15)N values in macroalgal tissues indicated that macroalgae in nearshore lagoons assimilate wastewater-derived nitrogen, whereas those on nearshore ocean reef flats assimilate nitrogen from other sources. These results suggest that increases in the human population result in high nutrient loading in groundwater and possibly into nearshore waters. High nutrient inputs into ambient seawater may have both direct and indirect negative effects on sand-producing foraminifers through habitat changes and/or the collapse of algal symbiosis. Copyright 2010 Elsevier Ltd. All rights reserved.

KSC-03pd1389

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - A view inside the pilot house of the Liberty Star. The ship is taking part in an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks. The banks are a marine protected area, 20 miles offshore of the east coast of Florida. The equipment includes an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1381

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - Underwater equipment sits on the deck of the Liberty Star, which will be the site of an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. A team of scientists will deploy an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1390

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - The Liberty Star makes its way along the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. The ship is taking part in an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks. Equipment being used for the research includes an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1382

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - Underwater equipment is checked on the deck of the Liberty Star, which will be the site of an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. A team of scientists will deploy an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1386

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - Underwater research equipment slowly sinks into the water. An undersea expedition is underway to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. The equipment includes an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries and will take place onboard the Liberty Star. The ship departed from Port Canaveral April 29 and will return May 9.

Habitat surrounding patch reefs influences the diet and nutrition of the western rock lobster

EPA Science Inventory

In this study the influence of habitat on the diet and nutrition of a common reef-associated generalist consumer, the western rock lobster Panulirus cygnus, was tested. Stable isotopes (13C/12C and 15N/14N) and gut contents were used to assess the diet of lobsters collected from ...

Composition and abundance of zooplankton groups from a coral reef lagoon in Puerto Morelos, Quintana Roo, Mexico, during an annual cycle.

PubMed

Alvarez-Cadena, José N; Ordóñez-López, Uriel; Almaral-Mendivil, Alma Rosa; Uicab-Sabido, Amira

2009-09-01

Zooplankton sampling was carried out monthly from January to December 1990 at station A near the coastline, and station B near the reef barrier, in a tropical coral reef lagoon in the Mexican Caribbean Sea. Samplings were made at midnight, near surface, with a conical net (mouth 0.40 m, mesh 330 microm) for 10 min. Salinity varied from 35.1 to 36.3 psu and temperature from 26.3 to 30.2 degrees C. The Bray-Curtis test applied to these results has defined two seasons: the dry season from November to May, and the wet season from June to October. A total of 37 zooplankton groups were found. Copepods were the most abundant contributing 49.0% of the total capture with Acartia espinata, Calanopia americana and Farranula gracilis as the most numerous. In the total zooplankton, however, cirripeds captured in only 15 samples of 24 were second in abundance (20.9%). Decapods, present all year-round and more abundant during the wet season, were third and contributed 19.2%. The rest of the groups were scarce and only amphipods (2.4%) and larvaceans (2.0%) were relatively abundant. The abundance of captured organisms correlated with the abiotic factors measured, thus, in the dry season, abundance was lower (mean 7.3 orgs/m3), while in the wet season the mean catch was 36.8 orgs/m3.

Earth Observation

NASA Image and Video Library

2014-08-30

ISS040E112662 (08/30/2014) ---- Cancún, Mexico. A long lens was used by astronauts aboard the International Space Station to take this image, and it highlights many natural and built features. The street pattern of Mexico’s tourist mecca, Cancún, contrasts with the waterways of the marinas that open into the bay and the lagoons. Brilliant blue water over coral reefs contrast with the dark waters of inland lagoons. The reefs are the second largest reef system on Earth, and draw tourists from all over the world. The wide, well developed beach on the gulf coast (image upper right) is the result of vigorous wave energy; the white sand makes the beach easily visible from space. But wave energy is reduced along Cancún’s protected shoreline (image center) and the beaches are thin or non-existant. Fair-weather cumulus clouds are scattered across the image top left. To shoot crisp mages with long lenses, astronaut photographers must learn to brace themselves against the ISS bulkhead to prevent any slight shaking that would blur or “smear” the picture. Counterintuitively, they then need to move the camera carefully retaining the target at the same point in the viewfinder (the landscape moves across the viewfinder quickly with long lenses). This is called tracking the target and requires good coordination by the photographer—again, to prevent blurring. Shorter lenses do not require this skill because the image appears to pass more slowly across the viewfinder.

Benthic communities at two remote Pacific coral reefs: effects of reef habitat, depth, and wave energy gradients on spatial patterns.

PubMed

Williams, Gareth J; Smith, Jennifer E; Conklin, Eric J; Gove, Jamison M; Sala, Enric; Sandin, Stuart A

2013-01-01

Kingman Reef and Palmyra Atoll in the central Pacific are among the most remote coral reefs on the planet. Here we describe spatial patterns in their benthic communities across reef habitats and depths, and consider these in the context of oceanographic gradients. Benthic communities at both locations were dominated by calcifying organisms (54-86% cover), namely hard corals (20-74%) and crustose coralline algae (CCA) (10-36%). While turf algae were relatively common at both locations (8-22%), larger fleshy macroalgae were virtually absent at Kingman (<1%) and rare at Palmyra (0.7-9.3%). Hard coral cover was higher, but with low diversity, in more sheltered habitats such as Palmyra's backreef and Kingman's patch reefs. Almost exclusive dominance by slow-growing Porites on Kingman's patch reefs provides indirect evidence of competitive exclusion, probably late in a successional sequence. In contrast, the more exposed forereef habitats at both Kingman and Palmyra had higher coral diversity and were characterized by fast-growing corals (e.g., Acropora and Pocillopora), indicative of more dynamic environments. In general at both locations, soft coral cover increased with depth, likely reflecting increasingly efficient heterotrophic abilities. CCA and fleshy macroalgae cover decreased with depth, likely due to reduced light. Cover of other calcified macroalgae, predominantly Halimeda, increased with depth. This likely reflects the ability of many calcifying macroalgae to efficiently harvest light at deeper depths, in combination with an increased nutrient supply from upwelling promoting growth. At Palmyra, patterns of hard coral cover with depth were inconsistent, but cover peaked at mid-depths at Kingman. On Kingman's forereef, benthic community composition was strongly related to wave energy, with hard coral cover decreasing and becoming more spatially clustered with increased wave energy, likely as a result of physical damage leading to patches of coral in localized shelter. In contrast, the cover of turf algae at Kingman was positively related to wave energy, reflecting their ability to rapidly colonize newly available space. No significant patterns with wave energy were observed on Palmyra's forereef, suggesting that a more detailed model is required to study biophysical coupling there. Kingman, Palmyra, and other remote oceanic reefs provide interesting case studies to explore biophysical influences on benthic ecology and dynamics.

Benthic communities at two remote Pacific coral reefs: effects of reef habitat, depth, and wave energy gradients on spatial patterns

PubMed Central

Conklin, Eric J.; Gove, Jamison M.; Sala, Enric; Sandin, Stuart A.

2013-01-01

Kingman Reef and Palmyra Atoll in the central Pacific are among the most remote coral reefs on the planet. Here we describe spatial patterns in their benthic communities across reef habitats and depths, and consider these in the context of oceanographic gradients. Benthic communities at both locations were dominated by calcifying organisms (54–86% cover), namely hard corals (20–74%) and crustose coralline algae (CCA) (10–36%). While turf algae were relatively common at both locations (8–22%), larger fleshy macroalgae were virtually absent at Kingman (<1%) and rare at Palmyra (0.7–9.3%). Hard coral cover was higher, but with low diversity, in more sheltered habitats such as Palmyra’s backreef and Kingman’s patch reefs. Almost exclusive dominance by slow-growing Porites on Kingman’s patch reefs provides indirect evidence of competitive exclusion, probably late in a successional sequence. In contrast, the more exposed forereef habitats at both Kingman and Palmyra had higher coral diversity and were characterized by fast-growing corals (e.g., Acropora and Pocillopora), indicative of more dynamic environments. In general at both locations, soft coral cover increased with depth, likely reflecting increasingly efficient heterotrophic abilities. CCA and fleshy macroalgae cover decreased with depth, likely due to reduced light. Cover of other calcified macroalgae, predominantly Halimeda, increased with depth. This likely reflects the ability of many calcifying macroalgae to efficiently harvest light at deeper depths, in combination with an increased nutrient supply from upwelling promoting growth. At Palmyra, patterns of hard coral cover with depth were inconsistent, but cover peaked at mid-depths at Kingman. On Kingman’s forereef, benthic community composition was strongly related to wave energy, with hard coral cover decreasing and becoming more spatially clustered with increased wave energy, likely as a result of physical damage leading to patches of coral in localized shelter. In contrast, the cover of turf algae at Kingman was positively related to wave energy, reflecting their ability to rapidly colonize newly available space. No significant patterns with wave energy were observed on Palmyra’s forereef, suggesting that a more detailed model is required to study biophysical coupling there. Kingman, Palmyra, and other remote oceanic reefs provide interesting case studies to explore biophysical influences on benthic ecology and dynamics. PMID:23734341

Paleotopography and substrate lithology as controls on initiation of Waulsortian Reef Growth: examples from Sacramento Mountains, New Mexico

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ahr, W.M.; Blount, W.M.; George, P.G.

1986-05-01

Frameless mud mounds, usually called Waulsortian reefs, are common in Osagean and Kinderhookian rocks of North America and western Europe. Spectacular Waulsortian reefs crop out in the Sacramento Mountains of New Mexico along 10 mi of continuous exposure, where detailed petrographic studies and field measurements of the strata between the top of the Devonian and the base of the reefs reveal: (1) down-to-the-southwest paleoslope on an uneven, gently dipping ramp; (2) widespread deposition of skeletal packstones and siliciclastics to the northeast; (3) patchy, local thicks of skeletal packstones surrounded by shaly wackestones to the southwest; (4) relict highs on themore » Devonian surface beneath the skeletal packstone pods; (5) clusters of sheetlike reefs weakly associated with paleotopography in the northern outcrops; and (6) large, dome-like individual reefs strongly associated with depositional topography and skeletal packstone/grainstone substrates in the southern outcrops. The pre-reef strata do not exhibit abrupt changes in thickness or lithology to indicate a break in regional slope, and the reefs are not aligned with patterns in thickness of facies that would distinguish shelf-edge environments from lagoonal environments. Like their European counterparts, the Osagean reefs in the Sacramento Mountains grew on a ramp where the nonreef facies were grainy updip and muddy downdip, and reef anatomy varied from sheetlike updip to dome-like downdip. The association between paleotopography, substrate lithology, and the initiation of Waulsortian reef growth provides new information about regional depositional patterns in the Early Mississippian.« less

The role of the reef-dune system in coastal protection in Puerto Morelos (Mexico)

NASA Astrophysics Data System (ADS)

Franklin, Gemma L.; Torres-Freyermuth, Alec; Medellin, Gabriela; Allende-Arandia, María Eugenia; Appendini, Christian M.

2018-04-01

Reefs and sand dunes are critical morphological features providing natural coastal protection. Reefs dissipate around 90 % of the incident wave energy through wave breaking, whereas sand dunes provide the final natural barrier against coastal flooding. The storm impact on coastal areas with these features depends on the relative elevation of the extreme water levels with respect to the sand dune morphology. However, despite the importance of barrier reefs and dunes in coastal protection, poor management practices have degraded these ecosystems, increasing their vulnerability to coastal flooding. The present study aims to theoretically investigate the role of the reef-dune system in coastal protection under current climatic conditions at Puerto Morelos, located in the Mexican Caribbean Sea, using a widely validated nonlinear non-hydrostatic numerical model (SWASH). Wave hindcast information, tidal level, and a measured beach profile of the reef-dune system in Puerto Morelos are employed to estimate extreme runup and the storm impact scale for current and theoretical scenarios. The numerical results show the importance of including the storm surge when predicting extreme water levels and also show that ecosystem degradation has important implications for coastal protection against storms with return periods of less than 10 years. The latter highlights the importance of conservation of the system as a mitigation measure to decrease coastal vulnerability and infrastructure losses in coastal areas in the short to medium term. Furthermore, the results are used to evaluate the applicability of runup parameterisations for beaches to reef environments. Numerical analysis of runup dynamics suggests that runup parameterisations for reef environments can be improved by including the fore reef slope. Therefore, future research to develop runup parameterisations incorporating reef geometry features (e.g. reef crest elevation, reef lagoon width, fore reef slope) is warranted.

Central-place foraging and ecological effects of an invasive predator across multiple habitats.

PubMed

Benkwitt, Cassandra E

2016-10-01

Cross-habitat foraging movements of predators can have widespread implications for predator and prey populations, community structure, nutrient transfer, and ecosystem function. Although central-place foraging models and other aspects of optimal foraging theory focus on individual predator behavior, they also provide useful frameworks for understanding the effects of predators on prey populations across multiple habitats. However, few studies have examined both the foraging behavior and ecological effects of nonnative predators across multiple habitats, and none has tested whether nonnative predators deplete prey in a manner predicted by these foraging models. I conducted behavioral observations of invasive lionfish (Pterois volitans) to determine whether they exhibit foraging movements similar to other central-place consumers. Then, I used a manipulative field experiment to test whether their effects on prey populations are consistent with three qualitative predictions from optimal foraging models. Specifically, I predicted that the effects of invasive lionfish on native prey will (1) occur at central sites first and then in surrounding habitats, (2) decrease with increasing distance away from their shelter site, and (3) extend to greater distances when prey patches are spaced closer together. Approximately 40% of lionfish exhibited short-term crepuscular foraging movements into surrounding habitats from the coral patch reefs where they shelter during daylight hours. Over the course of 7 weeks, lionfish depleted native fish populations on the coral patch reefs where they reside, and subsequently on small structures in the surrounding habitat. However, their effects did not decrease with increasing distance from the central shelter site and the influence of patch spacing was opposite the prediction. Instead, lionfish always had the greatest effects in areas with the highest prey densities. The differences between the predicted and observed effects of lionfish foraging are likely due to different constraints faced by invasive predators compared to native predators, namely that lionfish do not face increased predation risk with increased movement away from shelter sites. By foraging at greater distances from patch reefs than native predators, lionfish eliminated a spatial refuge from predation used by juveniles of many commercially and ecologically important reef fishes. © 2016 by the Ecological Society of America.

Resilience of predators to fishing pressure on coral patch reefs

USGS Publications Warehouse

Schroeder, R.E.; Parrish, J.D.

2005-01-01

Numbers and biomass of piscivorous fish and their predation on other fish may often be high in undisturbed coral reef communities. The effects of such predation have sometimes been studied by removal of piscivores (either experimentally or by fishermen). Such perturbations have usually involved removal of large, highly vulnerable, mobile piscivores that are often actively sought in fisheries. The effects of fishing on smaller, demersal, semi-resident piscivores have been little studied. We studied such effects on the fish communities of patch reefs at Midway atoll by experimentally removing major resident, demersal, piscivorous fishes. First, four control reefs and four experimental reefs were selected, their dimensions and habitats mapped, and their visible fish communities censused repeatedly over 1 year. Census of all control and experimental reefs was continued for the following 39 months, during which known piscivores were collected repeatedly by hand spearing. Records were kept of catch and effort to calculate CPUE as an index of predator density. Spearfishing on the experimental reefs removed 2504 piscivorous fish from 12 families and 43 taxa (mostly species). The species richness of the catch did not show an overall change over the duration of the experiment. Spearman rank correlation analysis showed some unexpected positive correlations for density in numbers and biomass of major fished piscivorous groups (especially lizardfish) over the experiment. Only two relatively minor fished piscivorous taxa declined in abundance over the experiment, while the overall abundance of piscivores increased. Visual censuses of fish on the experimental reefs also failed to show reduction of total piscivores over the full experimental period. No significant trend in the abundance of lizardfish censused over the full period was apparent on any of the control reefs. The high resilience of piscivores on these experimental reefs to relatively intense fishing pressure could result from their protracted recruitment seasons, high immigration rates, cryptic habits, or naturally high abundances. A major factor was the high immigration rates of lizardfish, replacing lizardfish and other less mobile piscivores removed from the reefs by spearing. On the fished reefs, the removed lizardfish population replaced itself >20 times during the experiment; other piscivorous taxa replaced themselves only 5 times.

Stable nitrogen isotopes in the turtle grass Thalassia testudinum from the Mexican Caribbean: Implications of anthropogenic development

NASA Astrophysics Data System (ADS)

Sánchez, Alberto; Ortiz-Hernández, Ma. Concepción; Talavera-Sáenz, Ana; Aguíñiga-García, Sergio

2013-12-01

Nutrient inputs associated with population growth threaten the integrity of coastal ecosystems. To assess the rapid increase in tourism, we compared the δ15N from Thalassia testudinum collected at sites with different levels of tourism development to detect the N inputs of wastewater discharge (WD) along the coast of Quintana Roo. The contributions of nitrogen enriched in 15N are directly related to the increase of WD inputs in areas of tourism development (Nichupte Lagoon in Cancun) and decreased toward Bahia Akumal and Tulum. The δ15N from T. testudinum was significantly lower at Mahahual and Puerto Morelos. In areas of the lowest development and with tourist activity restricted, such as the Yum Balam Reserve and Sian Ka'an Biosphere Reserve, the δ15N values were relatively enriched compared to Mahahual and Puerto Morelos. Therefore, Puerto Morelos and Mahahual may be used for baseline isotopic monitoring where tourist activities are growing and can lead to environmental pressure on the reef lagoon ecosystem. The anthropogenic N input has the potential to impact, both environmentally and economically, the seagrass meadows and the coral reefs along the coast of Quintana Roo and the Caribbean.

Interactive effects of live coral and structural complexity on the recruitment of reef fishes

NASA Astrophysics Data System (ADS)

Coker, D. J.; Graham, N. A. J.; Pratchett, M. S.

2012-12-01

Corals reefs are subjected to multiple disturbances that modify levels of coral cover and structural complexity of the reef matrix, and in turn influence the structure of associated fish communities. With disturbances predicted to increase, insight into how changes in substrate condition will influence the recruitment of many fishes is essential for understanding the recovery of reef fish populations following biological and physical disturbances. While studies have revealed that both live coral cover and structural complexity are important for many fishes, there is a lack of understanding regarding how a combination of these changes will impact the recruitment of fishes. This study used experimentally constructed patch reefs consisting of six different habitat treatments; three levels of live coral cover (high, medium, low) crossed with two levels of structural complexity (high, low), to test the independent and combined effects of live coral cover and structural complexity on the recruitment and recovery of fish communities. The abundance and species diversity of fishes varied significantly among the six habitat treatments, but differences were not clearly associated with either coral cover or structural complexity and varied through time. More striking, however, was a significant difference in the composition of fish assemblages among treatments, due mostly to disproportionate abundance of coral-dwelling fishes on high coral cover, high complexity reefs. Overall, it appears that coral cover had a more important influence than structural complexity, at least for the contrasting levels of structural complexity achieved on experimental patch reefs. Furthermore, we found that live coral cover is important for the recruitment of some non-coral-dependent fishes. This study confirms that live coral cover is critical for the maintenance of high biodiversity on tropical coral reefs, and that sustained and ongoing declines in coral cover will adversely affect recruitment for many different species of reef fishes.

Satellite remote sensing reveals a positive impact of living oyster reefs on microalgal biofilm development

NASA Astrophysics Data System (ADS)

Echappé, Caroline; Gernez, Pierre; Méléder, Vona; Jesus, Bruno; Cognie, Bruno; Decottignies, Priscilla; Sabbe, Koen; Barillé, Laurent

2018-02-01

Satellite remote sensing (RS) is routinely used for the large-scale monitoring of microphytobenthos (MPB) biomass in intertidal mudflats and has greatly improved our knowledge of MPB spatio-temporal variability and its potential drivers. Processes operating on smaller scales however, such as the impact of benthic macrofauna on MPB development, to date remain underinvestigated. In this study, we analysed the influence of wild Crassostrea gigas oyster reefs on MPB biofilm development using multispectral RS. A 30-year time series (1985-2015) combining high-resolution (30 m) Landsat and SPOT data was built in order to explore the relationship between C. gigas reefs and MPB spatial distribution and seasonal dynamics, using the normalized difference vegetation index (NDVI). Emphasis was placed on the analysis of a before-after control-impact (BACI) experiment designed to assess the effect of oyster killing on the surrounding MPB biofilms. Our RS data reveal that the presence of oyster reefs positively affects MPB biofilm development. Analysis of the historical time series first showed the presence of persistent, highly concentrated MPB patches around oyster reefs. This observation was supported by the BACI experiment which showed that killing the oysters (while leaving the physical reef structure, i.e. oyster shells, intact) negatively affected both MPB biofilm biomass and spatial stability around the reef. As such, our results are consistent with the hypothesis of nutrient input as an explanation for the MPB growth-promoting effect of oysters, whereby organic and inorganic matter released through oyster excretion and biodeposition stimulates MPB biomass accumulation. MPB also showed marked seasonal variations in biomass and patch shape, size and degree of aggregation around the oyster reefs. Seasonal variations in biomass, with higher NDVI during spring and autumn, were consistent with those observed on broader scales in other European mudflats. Our study provides the first multi-sensor RS satellite evidence of the promoting and structuring effect of oyster reefs on MPB biofilms.

A dataset on the species composition of amphipods (Crustacea) in a Mexican marine national park: Alacranes Reef, Yucatan

PubMed Central

Simões, Nuno; Pech, Daniel

2018-01-01

Abstract Background Alacranes Reef was declared as a National Marine Park in 1994. Since then, many efforts have been made to inventory its biodiversity. However, groups such as amphipods have been underestimated or not considered when benthic invertebrates were inventoried. Here we present a dataset that contributes to the knowledge of benthic amphipods (Crustacea, Peracarida) from the inner lagoon habitats from the Alacranes Reef National Park, the largest coral reef ecosystem in the Gulf of Mexico. The dataset contains information on records collected from 2009 to 2011. Data are available through Global Biodiversity Information Facility (GBIF). New information A total of 110 amphipod species distributed in 93 nominal species and 17 generic species, belonging to 71 genera, 33 families and three suborders are presented here. This information represents the first online dataset of amphipods from the Alacranes Reef National Park. The biological material is currently deposited in the crustacean collection from the regional unit of the National Autonomous University of Mexico located at Sisal, Yucatan, Mexico (UAS-Sisal). The biological material includes 588 data records with a total abundance of 6,551 organisms. The species inventory represents, until now, the richest fauna of benthic amphipods registered from any discrete coral reef ecosystem in Mexico. PMID:29416428

A dataset on the species composition of amphipods (Crustacea) in a Mexican marine national park: Alacranes Reef, Yucatan.

PubMed

Paz-Ríos, Carlos E; Simões, Nuno; Pech, Daniel

2018-01-01

Alacranes Reef was declared as a National Marine Park in 1994. Since then, many efforts have been made to inventory its biodiversity. However, groups such as amphipods have been underestimated or not considered when benthic invertebrates were inventoried. Here we present a dataset that contributes to the knowledge of benthic amphipods (Crustacea, Peracarida) from the inner lagoon habitats from the Alacranes Reef National Park, the largest coral reef ecosystem in the Gulf of Mexico. The dataset contains information on records collected from 2009 to 2011. Data are available through Global Biodiversity Information Facility (GBIF). A total of 110 amphipod species distributed in 93 nominal species and 17 generic species, belonging to 71 genera, 33 families and three suborders are presented here. This information represents the first online dataset of amphipods from the Alacranes Reef National Park. The biological material is currently deposited in the crustacean collection from the regional unit of the National Autonomous University of Mexico located at Sisal, Yucatan, Mexico (UAS-Sisal). The biological material includes 588 data records with a total abundance of 6,551 organisms. The species inventory represents, until now, the richest fauna of benthic amphipods registered from any discrete coral reef ecosystem in Mexico.

Population structure, spatial distribution and life-history traits of blacktip reef sharks Carcharhinus melanopterus.

PubMed

Mourier, J; Mills, S C; Planes, S

2013-03-01

During a survey of the population of blacktip reef shark Carcharhinus melanopterus in Moorea (French Polynesia) between 2007 and 2011, population structural characteristics were estimated from 268 individuals. Total length (LT ) ranged from 48 to 139 cm and 48 to 157 cm for males and females, respectively, demonstrating that the average LT of females was larger than that of males. The C. melanopterus population at Moorea showed an apparent spatial sexual segregation with females preferentially frequenting lagoons and males the fore-reefs. Mean growth rate was c. 6 cm year(-1) . Males reached sexual maturity at 111 cm LT . This study reports on the population characteristics of this widespread carcharhinid shark species and makes comparisons with other locations, confirming high geographic variability in the population structure of the species. © 2013 The Authors. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

Phytotoxicity induced in isolated zooxanthellae by herbicides extracted from Great Barrier Reef flood waters.

PubMed

Shaw, C M; Brodie, J; Mueller, J F

2012-01-01

To date there has been limited evidence anthropogenically sourced pollution from catchments reaching corals of the Great Barrier Reef (GBR). In this study, freshly isolated zooxanthellae were exposed to polar chemicals (chiefly herbicides) extracted from water samples collected in a flood plume in the GBR lagoon. Photosynthetic potential of the isolated zooxanthellae declined after exposure to concentrated extracts (10 times) from all but one of the sampling sites. Photosynthetic potential demonstrated a significant positive relationship with the concentration of diuron in the concentrated extracts and a significant inverse relationship with salinity measured at the sampling site. This study demonstrates that runoff from land based application of herbicides may reduce photosynthetic efficiency in corals of inshore reefs in the GBR. The ecological impacts of the chemicals in combination with other potential stressors on corals remain unclear. Copyright © 2012 Elsevier Ltd. All rights reserved.

Status and conservation of coral reefs in Costa Rica.

PubMed

Cortés, Jorge; Jiménez, Carlos E; Fonseca, Ana C; Alvarado, Juan José

2010-05-01

Costa Rica has coral communities and reefs on the Caribbean coast and on the Pacific along the coast and off-shore islands. The Southern section of the Caribbean coast has fringing and patch reefs, carbonate banks, and an incipient algal ridge. The Pacific coast has coral communities, reefs and isolated coral colonies. Coral reefs have been seriously impacted in the last 30 years, mainly by sediments (Caribbean coast and some Pacific reefs) and by El Niño warming events (both coasts). Monitoring is being carried out at three sites on each coast. Both coasts suffered significant reductions in live coral cover in the 1980's, but coral cover is now increasing in most sites. The government of Costa Rica is aware of the importance of coral reefs and marine environments in general, and in recent years decrees have been implemented (or are in the process of approval) to protect them, but limited resources endanger their proper management and conservation, including proper outreach to reef users and the general public.

KSC-03pd1385

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - A team onboard the Liberty Star, the NASA Space Shuttle support ship operated by United Space Alliance, get ready to lower underwater research equipment into the water. An undersea expedition is underway to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. The equipment includes an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1384

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - Underwater research equipment is prepared for immersion from the Liberty Star, the NASA Space Shuttle support ship operated by United Space Alliance. It is being used on an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. The equipment includes an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1377

NASA Image and Video Library

2003-04-29

KENNEDY SPACE CENTER, FLA. - Pictured is equipment that will be used on an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. Scientists on the team will be deploying an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS). Dr. Grant Gilmore was co-principle investigator of the PAMS, originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries and will take place onboard the Liberty Star. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1383

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - John Reed, co-principal investigator, Harbor Branch Oceanographic Institution, points to the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. A team of scientists will deploy an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), on an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks. The PAMS was originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries and will take place onboard the Liberty Star. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1388

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - A view from inside the pilot house of the Liberty Star overlooks the stern where a team secures lines to underwater research equipment being used on an expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks. The banks are a marine protected area, 20 miles offshore of the east coast of Florida. The equipment includes an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS), originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

Snorkelling and trampling in shallow-water fringing reefs: Risk assessment and proposed management strategy

PubMed Central

Hannak, Judith S.; Kompatscher, Sarah; Stachowitsch, Michael; Herler, Jürgen

2011-01-01

Shallow reefs (reef flats <1.5 m) in the northern Red Sea are impacted by growing tourism that includes swimmers, snorkellers and reef walkers but have largely been neglected in past studies. We selected a fringing reef along the lagoon of Dahab (Sinai, Egypt) as a model for a management strategy. Point-intercept line transects were used to determine substrate composition, coral community and condition, and the coral damage index (CDI) was applied. Approximately 84% of the coral colonies showed signs of damage such as breakage, partial mortality or algal overgrowth, especially affecting the most frequent coral genus Acropora. Questionnaires were used to determine the visitors’ socio-economic background and personal attitudes regarding snorkelling, SCUBA-diving and interest in visiting a prospective snorkelling trail. Experiencing nature (97%) was by far the strongest motivation, and interest in further education about reef ecology and skill training was high. Less experienced snorkellers and divers – the target group for further education and skill training – were those most prepared to financially support such a trail. We therefore recommend a guided underwater snorkelling trail and restricting recreational use to a less sensitive ‘ecotourism zone’ while protecting the shallow reef flat. Artificial structures can complete the trail and offer the opportunity to snorkel over deeper areas at unfavourable tide or wind conditions. This approach provides a strategy for the management and conservation of shallow-water reefs, which are facing increasing human impact here and elsewhere. PMID:21708420

Snorkelling and trampling in shallow-water fringing reefs: risk assessment and proposed management strategy.

PubMed

Hannak, Judith S; Kompatscher, Sarah; Stachowitsch, Michael; Herler, Jürgen

2011-10-01

Shallow reefs (reef flats <1.5 m) in the northern Red Sea are impacted by growing tourism that includes swimmers, snorkellers and reef walkers but have largely been neglected in past studies. We selected a fringing reef along the lagoon of Dahab (Sinai, Egypt) as a model for a management strategy. Point-intercept line transects were used to determine substrate composition, coral community and condition, and the coral damage index (CDI) was applied. Approximately 84% of the coral colonies showed signs of damage such as breakage, partial mortality or algal overgrowth, especially affecting the most frequent coral genus Acropora. Questionnaires were used to determine the visitors' socio-economic background and personal attitudes regarding snorkelling, SCUBA-diving and interest in visiting a prospective snorkelling trail. Experiencing nature (97%) was by far the strongest motivation, and interest in further education about reef ecology and skill training was high. Less experienced snorkellers and divers--the target group for further education and skill training--were those most prepared to financially support such a trail. We therefore recommend a guided underwater snorkelling trail and restricting recreational use to a less sensitive 'ecotourism zone' while protecting the shallow reef flat. Artificial structures can complete the trail and offer the opportunity to snorkel over deeper areas at unfavourable tide or wind conditions. This approach provides a strategy for the management and conservation of shallow-water reefs, which are facing increasing human impact here and elsewhere. Copyright © 2011 Elsevier Ltd. All rights reserved.

Metamorphosing reef fishes avoid predator scent when choosing a home.

PubMed

Vail, Alexander L; McCormick, Mark I

2011-12-23

Most organisms possess anti-predator adaptations to reduce their risk of being consumed, but little is known of the adaptations prey employ during vulnerable life-history transitions when predation pressures can be extreme. We demonstrate the use of a transition-specific anti-predator adaptation by coral reef fishes as they metamorphose from pelagic larvae to benthic juveniles, when over half are consumed within 48 h. Our field experiment shows that naturally settling damselfish use olfactory, and most likely innate, predator recognition to avoid settling to habitat patches manipulated to emit predator odour. Settlement to patches emitting predator odour was on average 24-43% less than to control patches. Evidence strongly suggests that this avoidance of sedentary and patchily distributed predators by nocturnal settlers will gain them a survival advantage, but also lead to non-lethal predator effects: the costs of exhibiting anti-predator adaptations. Transition-specific anti-predator adaptations, such as demonstrated here, may be widespread among organisms with complex life cycles and play an important role in prey population dynamics.

Is Echinometra viridis facilitating a phase shift on an Acropora cervicornis patch reef in Belize?

NASA Astrophysics Data System (ADS)

Stefanic, C. M.; Greer, L.; Norvell, D.; Benson, W.; Curran, H.

2012-12-01

Coral reef health is in rapid decline across the Caribbean due to a number of anthropogenic and natural disturbances. A phase shift from coral- to macroalgae-dominant reefs is pervasive and has been well documented. Acropora cervicornis (Staghorn Coral) has been particularly affected by this shift due to mass mortality of this species since the 1980s. In recent years few Caribbean A. cervicornis refugia have been documented. This study characterizes the relationship between coral and grazing urchins on a rare patch reef system dominated by A. cervicornis off the coast of Belize. To assess relative abundance of live A. cervicornis and the urchin Echinometra viridis, photographs and urchin abundance data were collected from 132 meter square quadrats along five transects across the reef. Photographs were digitized and manually segmented using Adobe Illustrator, and percent live coral cover and branch tip densities were calculated using Matlab. Mean percent live coral cover across all transects was 24.4 % with a high of 65% live coral per meter square. Average urchin density was 18.5 per quadrat, with an average density per transect ranging from 22.1 to 0.5 per quadrat. Up to over 400 live A. cervicornis branch tips per quadrat were observed. Data show a positive correlation between E. viridis abundance and live A. cervicornis, suggesting that these urchins are facilitating recovery or persistence of this endangered coral species. These results suggest the relationship between E. viridis and A. cervicornis could be a key element in a future reversal of the coral to macroalgae phase shift on some Caribbean coral reefs.

Exposure of inshore corals to suspended sediments due to wave-resuspension and river plumes in the central Great Barrier Reef: A reappraisal

NASA Astrophysics Data System (ADS)

Orpin, Alan R.; Ridd, Peter V.

2012-09-01

Suspended sediment in the coastal zone is an important limiting factor for the growth and health of inshore coral reefs. The Great Barrier Reef (GBR) lagoon receives sediment from a number of tropical rivers and the physical and biological effects of riverine discharge and turbidity within the lagoon are of considerable scientific and public interest. Published data from two inshore regions of the GBR are reviewed herein to evaluate the relative influence of river plumes and wave resuspension on suspended sediment concentration (SSC) around coral communities over a range of timescales. Data from Cleveland Bay and from other sites near the mouth of the Tully River show that wave resuspension is the most dominant mechanism controlling SSC at inshore reefs. At many nearshore areas today fine-grained bed sediment is abundant, consistent with millennial-scale geological evidence of sediment dispersal prior to European settlement and catchment impacts. Flocculation, particle settling and dilution occurs within the river plume, and riverine sediment concentrations at reefs directly attributable to individual flood inputs is significantly reduced, suggesting that the plume component is a relatively small contribution to the total suspended sediment mass balance over inter-annual timescales. Resuspension events can generate higher ambient SSC than that measured in flood waters (e.g. Tully River). In addition, while visually spectacular, satellite and aerial images offer limited quantitative information of total sediment load carried by hypopycnal plumes, as many of these plumes may contain algal blooms but relatively low concentrations of suspended sediment (ca. <5 mg/l). Nonetheless, the cumulative effect of sediment-laden plumes may be a vector for other adsorbed contaminants of potential ecological concern, but coral smothering by hypopycnal plumes alone appears an unlikely impact particularly at inner- and middle-shelf reefs exposed to high wave energy and resuspension. Terrigenous sediment dispersal and turbidity within the GBR is governed by physical processes common to many continental shelves globally. Despite the examples examined in detail herein, the role of frequency, magnitude and duration in determining the impact or exposure of corals to elevated SSCs is poorly constrained by limited quantitative measurements during events, and our ability to place these into a broader temporal context. More high-quality observational data, at meaningful length-scales, can only enhance our ability to disentangle potential behavioural shifts in environmental responses.

Origin of Silurian reefs in the Alexander Terrane of southeastern Alaska

DOE Office of Scientific and Technical Information (OSTI.GOV)

Soja, C.M.

1991-04-01

Lower to Upper Silurian (upper Llandovery-Ludlow) limestones belonging to the Heceta Formation record several episodes of reef growth in the Alexander terrane of southeastern Alaska. As the oldest carbonates of wide-spread distribution in the region, the Heceta limestones represent the earliest development of a shallow-marine platform within the Alexander arc and the oldest foundation for reef evolution. These deposits provide important insights into the dynamic processes, styles, and bathymetry associated with reef growth in tectonically active oceanic islands. Massive stromatoporoids, corals, and red algae are preserved in fragmental rudstones and represent a fringing reef that formed at the seaward edgemore » of the incipient marine shelf. Accessory constituents in this reef include crinoids and the cyanobacterium Girvanella. Small biostromes were constructed by ramose corals and stromatoporoids on oncolitic substrates in backreef or lagoonal environments. These buildups were associated with low-diversity assemblages of brachiopods and with gastropods, amphiporids, calcareous algae and cyanobacteria. Microbial boundstones reflect the widespread encrustation of cyanobacteria and calcified microproblematica on shelly debris as stromatolitic mats that resulted in the development of a stromatactoid-bearing mud mound and a barrier reef complex. Epiphytaceans, other microbes, and aphrosalpingid sponges were the primary frame-builders of the barrier reefs. These buildups attained significant relief at the shelf margin and shed detritus as slumped blocks and debris flows into deep-water sites along the slope. The similarity of these stromatolitic-aphrosalpingid reefs to those from Siluro-Devonian strata of autochthonous southwestern Alaska suggests paleobiogeographic ties of the Alexander terrane to cratonal North America during the Silurian.« less

Climate-driven coral reorganisation influences aggressive behaviour in juvenile coral-reef fishes

NASA Astrophysics Data System (ADS)

Kok, Judith E.; Graham, Nicholas A. J.; Hoogenboom, Mia O.

2016-06-01

Globally, habitat degradation is altering the abundance and diversity of species in a variety of ecosystems. This study aimed to determine how habitat degradation, in terms of changing coral composition under climate change, affected abundance, species richness and aggressive behaviour of juveniles of three damselfishes ( Pomacentrus moluccensis, P. amboinensis and Dischistodus perspicillatus, in order of decreasing reliance on coral). Patch reefs were constructed to simulate two types of reefs: present-day reefs that are vulnerable to climate-induced coral bleaching, and reefs with more bleaching-robust coral taxa, thereby simulating the likely future of coral reefs under a warming climate. Fish communities were allowed to establish naturally on the reefs during the summer recruitment period. Climate-robust reefs had lower total species richness of coral-reef fishes than climate-vulnerable reefs, but total fish abundance was not significantly different between reef types (pooled across all species and life-history stages). The nature of aggressive interactions, measured as the number of aggressive chases, varied according to coral composition; on climate-robust reefs, juveniles used the substratum less often to avoid aggression from competitors, and interspecific aggression became relatively more frequent than intraspecific aggression for juveniles of the coral-obligate P. moluccensis. This study highlights the importance of coral composition as a determinant of behaviour and diversity of coral-reef fishes.

Resilience in carbonate production despite three coral bleaching events in 5 years on an inshore patch reef in the Florida Keys.

PubMed

Manzello, Derek P; Enochs, Ian C; Kolodziej, Graham; Carlton, Renée; Valentino, Lauren

2018-01-01

The persistence of coral reef frameworks requires that calcium carbonate (CaCO 3 ) production by corals and other calcifiers outpaces CaCO 3 loss via physical, chemical, and biological erosion. Coral bleaching causes declines in CaCO 3 production, but this varies with bleaching severity and the species impacted. We conducted census-based CaCO 3 budget surveys using the established ReefBudget approach at Cheeca Rocks, an inshore patch reef in the Florida Keys, annually from 2012 to 2016. This site experienced warm-water bleaching in 2011, 2014, and 2015. In 2017, we obtained cores of the dominant calcifying coral at this site, Orbicella faveolata , to understand how calcification rates were impacted by bleaching and how they affected the reef-wide CaCO 3 budget. Bleaching depressed O. faveolata growth and the decline of this one species led to an overestimation of mean (± std. error) reef-wide CaCO 3 production by + 0.68 (± 0.167) to + 1.11 (± 0.236) kg m -2  year -1 when using the static ReefBudget coral growth inputs. During non-bleaching years, the ReefBudget inputs slightly underestimated gross production by - 0.10 (± 0.022) to - 0.43 (± 0.100) kg m -2  year -1 . Carbonate production declined after the first year of back-to-back bleaching in 2014, but then increased after 2015 to values greater than the initial surveys in 2012. Cheeca Rocks is an outlier in the Caribbean and Florida Keys in terms of coral cover, carbonate production, and abundance of O. faveolata , which is threatened under the Endangered Species Act. Given the resilience of this site to repeated bleaching events, it may deserve special management attention.

Porites white patch syndrome: associated viruses and disease physiology

NASA Astrophysics Data System (ADS)

Lawrence, S. A.; Davy, J. E.; Wilson, W. H.; Hoegh-Guldberg, O.; Davy, S. K.

2015-03-01

In recent decades, coral reefs worldwide have undergone significant changes in response to various environmental and anthropogenic impacts. Among the numerous causes of reef degradation, coral disease is one factor that is to a large extent still poorly understood. Here, we characterize the physiology of white patch syndrome (WPS), a disease affecting poritid corals on the Great Barrier Reef. WPS manifests as small, generally discrete patches of tissue discolouration. Physiological analysis revealed that chlorophyll a content was significantly lower in lesions than in healthy tissues, while host protein content remained constant, suggesting that host tissue is not affected by WPS. This was confirmed by transmission electron microscope (TEM) examination, which showed intact host tissue within lesions. TEM also revealed that Symbiodinium cells are lost from the host gastrodermis with no apparent harm caused to the surrounding host tissue. Also present in the electron micrographs were numerous virus-like particles (VLPs), in both coral and Symbiodinium cells. Small (<50 nm diameter) icosahedral VLPs were significantly more abundant in coral tissue taken from diseased colonies, and there was an apparent, but not statistically significant, increase in abundance of filamentous VLPs in Symbiodinium cells from diseased colonies. There was no apparent increase in prokaryotic or eukaryotic microbial abundance in diseased colonies. Taken together, these results suggest that viruses infecting the coral and/or its resident Symbiodinium cells may be the causative agents of WPS.

Reflective Light Modulation by Cephalopods and Fishes in Shallow Nearshore Habitats

DTIC Science & Technology

2011-09-30

cephalopods ( octopus , cuttlefish and squid) because they have the most diverse and changeable camouflage patterns known in biology. Several fishes...breakdown is as follows: (1) Puerto Rico, December 2010, to film Octopus vulgaris using camouflage in various habitats, including seagrass, soft corals...patch reefs, and fully developed coral reefs with soft and hard corals; (2) Monterey, California, Hopkins Marine Station, to film Octopus rubescens, a

Bacterial communities associated with Porites white patch syndrome (PWPS) on three western Indian Ocean (WIO) coral reefs.

PubMed

Séré, Mathieu G; Tortosa, Pablo; Chabanet, Pascale; Turquet, Jean; Quod, Jean-Pascal; Schleyer, Michael H

2013-01-01

The scleractinian coral Porites lutea, an important reef-building coral on western Indian Ocean reefs (WIO), is affected by a newly-reported white syndrome (WS) the Porites white patch syndrome (PWPS). Histopathology and culture-independent molecular techniques were used to characterise the microbial communities associated with this emerging disease. Microscopy showed extensive tissue fragmentation generally associated with ovoid basophilic bodies resembling bacterial aggregates. Results of 16S rRNA sequence analysis revealed a high variability between bacterial communities associated with PWPS-infected and healthy tissues in P. lutea, a pattern previously reported in other coral diseases such as black band disease (BBD), white band disease (WBD) and white plague diseases (WPD). Furthermore, substantial variations in bacterial communities were observed at the different sampling locations, suggesting that there is no strong bacterial association in Porites lutea on WIO reefs. Several sequences affiliated with potential pathogens belonging to the Vibrionaceae and Rhodobacteraceae were identified, mainly in PWPS-infected coral tissues. Among them, only two ribotypes affiliated to Shimia marina (NR043300.1) and Vibrio hepatarius (NR025575.1) were consistently found in diseased tissues from the three geographically distant sampling localities. The role of these bacterial species in PWPS needs to be tested experimentally.

Near-surface enrichment of zooplankton over a shallow back reef: implications for coral reef food webs

NASA Astrophysics Data System (ADS)

Alldredge, A. L.; King, J. M.

2009-12-01

Zooplankton were 3-8 times more abundant during the day near the surface than elsewhere in the water column over a 1-2.4 m deep back reef in Moorea, French Polynesia. Zooplankton were also significantly more abundant near the surface at night although gradients were most pronounced under moonlight. Zooplankton in a unidirectional current became concentrated near the surface within 2 m of departing a well-mixed trough immediately behind the reef crest, indicating that upward swimming behavior, rather than near-bottom depletion by reef planktivores, was the proximal cause of these gradients. Zooplankton were highly enriched near the surface before and after a full lunar eclipse but distributed evenly throughout the water column during the eclipse itself supporting light as a proximal cue for the upward swimming behavior of many taxa. This is the first investigation of the vertical distribution of zooplankton over a shallow back reef typical of island barrier reef systems common around the world. Previous studies on deeper fringing reefs found zooplankton depletion near the bottom but no enrichment aloft. In Moorea, where seawater is continuously recirculated out the lagoon and back across the reef crest onto the back reef, selection for upward swimming behavior may be especially strong, because the surface serves both as a refuge from predation and an optimum location for retention within the reef system. Planktivorous fish and corals that can forage or grow even marginally higher in the water column might have a substantial competitive advantage over those nearer the bottom on shallow reefs. Zooplankton abundance varied more over a few tens of centimeters vertical distance than it did between seasons or even between day and night indicating that great care must be taken to accurately assess the availability of zooplankton as food on shallow reefs.

The effect of species and colony size on the bleaching response of reef-building corals in the Florida Keys during the 2005 mass bleaching event

NASA Astrophysics Data System (ADS)

Brandt, M. E.

2009-12-01

Understanding the variation in coral bleaching response is necessary for making accurate predictions of population changes and the future state of reefs in a climate of increasing thermal stress events. Individual coral colonies, belonging to inshore patch reef communities of the Florida Keys, were followed through the 2005 mass bleaching event. Overall, coral bleaching patterns followed an index of accumulated thermal stress more closely than in situ temperature measurements. Eight coral species ( Colpophyllia natans, Diploria strigosa, Montastraea cavernosa, M. faveolata, Porites astreoides, P. porites, Siderastrea siderea, and Stephanocoenia intersepta), representing >90% of the coral colonies studied, experienced intense levels of bleaching, but responses varied. Bleaching differed significantly among species: Colpophyllia natans and Diploria strigosa were most susceptible to thermal stress, while Stephanocoenia intersepta was the most tolerant. For colonies of C. natans, M. faveolata, and S. siderea, larger colonies experienced more extensive bleaching than smaller colonies. The inshore patch reef communities of the Florida Keys have historically been dominated by large colonies of Montastraea sp. and Colpophyllia natans. These results provide evidence that colony-level differences can affect bleaching susceptibility in this habitat and suggest that the impact of future thermal stress events may be biased toward larger colonies of dominant reef-building species. Predicted increases in the frequency of mass bleaching and subsequent mortality may therefore result in significant structural shifts of these ecologically important communities.

Reef Sound as an Orientation Cue for Shoreward Migration by Pueruli of the Rock Lobster, Jasus edwardsii

PubMed Central

Green, Bridget S.; Gardner, Caleb; Hesse, Jan; Stanley, Jenni A.

2016-01-01

The post-larval or puerulus stage of spiny, or rock, lobsters (Palinuridae) swim many kilometres from open oceans into coastal waters where they subsequently settle. The orientation cues used by the puerulus for this migration are unclear, but are presumed to be critical to finding a place to settle. Understanding this process may help explain the biological processes of dispersal and settlement, and be useful for developing realistic dispersal models. In this study, we examined the use of reef sound as an orientation cue by the puerulus stage of the southern rock lobster, Jasus edwardsii. Experiments were conducted using in situ binary choice chambers together with replayed recording of underwater reef sound. The experiment was conducted in a sandy lagoon under varying wind conditions. A significant proportion of puerulus (69%) swam towards the reef sound in calm wind conditions. However, in windy conditions (>25 m s-1) the orientation behaviour appeared to be less consistent with the inclusion of these results, reducing the overall proportion of pueruli that swam towards the reef sound (59.3%). These results resolve previous speculation that underwater reef sound is used as an orientation cue in the shoreward migration of the puerulus of spiny lobsters, and suggest that sea surface winds may moderate the ability of migrating pueruli to use this cue to locate coastal reef habitat to settle. Underwater sound may increase the chance of successful settlement and survival of this valuable species. PMID:27310676

Reef Sound as an Orientation Cue for Shoreward Migration by Pueruli of the Rock Lobster, Jasus edwardsii.

PubMed

Hinojosa, Ivan A; Green, Bridget S; Gardner, Caleb; Hesse, Jan; Stanley, Jenni A; Jeffs, Andrew G

2016-01-01

The post-larval or puerulus stage of spiny, or rock, lobsters (Palinuridae) swim many kilometres from open oceans into coastal waters where they subsequently settle. The orientation cues used by the puerulus for this migration are unclear, but are presumed to be critical to finding a place to settle. Understanding this process may help explain the biological processes of dispersal and settlement, and be useful for developing realistic dispersal models. In this study, we examined the use of reef sound as an orientation cue by the puerulus stage of the southern rock lobster, Jasus edwardsii. Experiments were conducted using in situ binary choice chambers together with replayed recording of underwater reef sound. The experiment was conducted in a sandy lagoon under varying wind conditions. A significant proportion of puerulus (69%) swam towards the reef sound in calm wind conditions. However, in windy conditions (>25 m s-1) the orientation behaviour appeared to be less consistent with the inclusion of these results, reducing the overall proportion of pueruli that swam towards the reef sound (59.3%). These results resolve previous speculation that underwater reef sound is used as an orientation cue in the shoreward migration of the puerulus of spiny lobsters, and suggest that sea surface winds may moderate the ability of migrating pueruli to use this cue to locate coastal reef habitat to settle. Underwater sound may increase the chance of successful settlement and survival of this valuable species.

KSC-03pd1380

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - John Reed, co-principal investigator, Harbor Branch Oceanographic Institution, checks out equipment on the Liberty Star, which will be the site of an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. He and other scientists will be deploying an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS). Dr. Grant Gilmore was co-principle investigator of the PAMS, originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1376

NASA Image and Video Library

2003-04-29

KENNEDY SPACE CENTER, FLA. - Dr. Grant Gilmore sits alongside some of the equipment that will be used on an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. Scientists on the team will be deploying an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS). Gilmore is co-principle investigator of the PAMS, originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries and will take place onboard the Liberty Star. The ship departed from Port Canaveral April 29 and will return May 9.

KSC-03pd1378

NASA Image and Video Library

2003-04-29

KENNEDY SPACE CENTER, FLA. - Pictured is a piece of equipment that will be used on an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. Scientists on the team will be deploying an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS). Dr. Grant Gilmore was co-principle investigator of the PAMS, originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries and will take place onboard the Liberty Star. The ship departed from Port Canaveral April 29 and will return May 9.

Last interglacial sea levels and regional tectonics from fossil coral reefs at the Gulf of Aqaba

NASA Astrophysics Data System (ADS)

Bar, N.; Agnon, A.; Yehudai, M.; Lazar, B.; Shaked, Y.; Stein, M.

2017-12-01

Elevated fossil reef terraces along the northeast coast of the Gulf of Aqaba (GOA) illuminate the history of tectonic uplift and sea-level changes during the last interglacial period. The terraces comprise fringing reefs, some with clear reef structure that includes a reef flat and a shallow back lagoon accurately marking sea-levels. U-Th ages of precipitation of aragonitic corals and recrystallization of aragonite to calcite corals from three terraces are used to constrain the local sea-level pattern. Terrace R3 was probably formed during an earlier stage of MIS5e at 130-132 ka and recrystallized to calcite at 124±8 ka. Terrace R2, comprising a wide and developed reef flat, formed during a stable sea level of MIS5e at 129-121 ka and recrystallized to calcite at 104±6 ka. Terrace R1 formed during a short still-stand at 117 ka. All terraces formed when sea level was a few meters above the modern GOA level. The recrystallization age of Terrace R2 implies that at around 104±6 ka (MIS5c) sea level was close to its MIS5e elevation. The tectonic setting is superimposed by local faulting that caused small vertical displacements within the terraces. The elevation and ages of the reef flats indicate a slow average uplift, 0.12±0.05 m/kyr, similar to rates inferred for other reef terraces along GOA and the Red Sea. This implies an overall long-term slow tectonic uplift of the Arabian lithosphere during the late Quaternary.

Hierarchical drivers of reef-fish metacommunity structure.

PubMed

MacNeil, M Aaron; Graham, Nicholas A J; Polunin, Nicholas V C; Kulbicki, Michel; Galzin, René; Harmelin-Vivien, Mireille; Rushton, Steven P

2009-01-01

Coral reefs are highly complex ecological systems, where multiple processes interact across scales in space and time to create assemblages of exceptionally high biodiversity. Despite the increasing frequency of hierarchically structured sampling programs used in coral-reef science, little progress has been made in quantifying the relative importance of processes operating across multiple scales. The vast majority of reef studies are conducted, or at least analyzed, at a single spatial scale, ignoring the implicitly hierarchical structure of the overall system in favor of small-scale experiments or large-scale observations. Here we demonstrate how alpha (mean local number of species), beta diversity (degree of species dissimilarity among local sites), and gamma diversity (overall species richness) vary with spatial scale, and using a hierarchical, information-theoretic approach, we evaluate the relative importance of site-, reef-, and atoll-level processes driving the fish metacommunity structure among 10 atolls in French Polynesia. Process-based models, representing well-established hypotheses about drivers of reef-fish community structure, were assembled into a candidate set of 12 hierarchical linear models. Variation in fish abundance, biomass, and species richness were unevenly distributed among transect, reef, and atoll levels, establishing the relative contribution of variation at these spatial scales to the structure of the metacommunity. Reef-fish biomass, species richness, and the abundance of most functional-groups corresponded primarily with transect-level habitat diversity and atoll-lagoon size, whereas detritivore and grazer abundances were largely correlated with potential covariates of larval dispersal. Our findings show that (1) within-transect and among-atoll factors primarily drive the relationship between alpha and gamma diversity in this reef-fish metacommunity; (2) habitat is the primary correlate with reef-fish metacommunity structure at multiple spatial scales; and (3) inter-atoll connectedness was poorly correlated with the nonrandom clustering of reef-fish species. These results demonstrate the importance of modeling hierarchical data and processes in understanding reef-fish metacommunity structure.

Mesopredator trophodynamics on thermally stressed coral reefs

NASA Astrophysics Data System (ADS)

Hempson, Tessa N.; Graham, Nicholas A. J.; MacNeil, M. Aaron; Hoey, Andrew S.; Almany, Glenn R.

2018-03-01

Ecosystems are becoming vastly modified through disturbance. In coral reef ecosystems, the differential susceptibility of coral taxa to climate-driven bleaching is predicted to shift coral assemblages towards reefs with an increased relative abundance of taxa with high thermal tolerance. Many thermally tolerant coral species are characterised by low structural complexity, with reduced habitat niche space for the small-bodied coral reef fishes on which piscivorous mesopredators feed. This study used a patch reef array to investigate the potential impacts of climate-driven shifts in coral assemblages on the trophodynamics of reef mesopredators and their prey communities. The `tolerant' reef treatment consisted only of coral taxa of low susceptibility to bleaching, while `vulnerable' reefs included species of moderate to high thermal vulnerability. `Vulnerable' reefs had higher structural complexity, and the fish assemblages that established on these reefs over 18 months had higher species diversity, abundance and biomass than those on `tolerant' reefs. Fish assemblages on `tolerant' reefs were also more strongly influenced by the introduction of a mesopredator ( Cephalopholis boenak). Mesopredators on `tolerant' reefs had lower lipid content in their muscle tissue by the end of the 6-week experiment. Such sublethal energetic costs can compromise growth, fecundity, and survivorship, resulting in unexpected population declines in long-lived mesopredators. This study provides valuable insight into the altered trophodynamics of future coral reef ecosystems, highlighting the potentially increased vulnerability of reef fish assemblages to predation as reef structure declines, and the cost of changing prey availability on mesopredator condition.

Correspondence between the distribution of hydrodynamic time parameters and the distribution of biological and chemical variables in a semi-enclosed coral reef lagoon

NASA Astrophysics Data System (ADS)

Torréton, Jean-Pascal; Rochelle-Newall, Emma; Jouon, Aymeric; Faure, Vincent; Jacquet, Séverine; Douillet, Pascal

2007-09-01

Hydrodynamic modeling can be used to spatially characterize water renewal rates in coastal ecosystems. Using a hydrodynamic model implemented over the semi-enclosed Southwest coral lagoon of New Caledonia, a recent study computed the flushing lag as the minimum time required for a particle coming from outside the lagoon (open ocean) to reach a specific station [Jouon, A., Douillet, P., Ouillon, S., Fraunié, P., 2006. Calculations of hydrodynamic time parameters in a semi-opened coastal zone using a 3D hydrodynamic model. Continental Shelf Research 26, 1395-1415]. Local e -flushing time was calculated as the time requested to reach a local grid mesh concentration of 1/e from the precedent step. Here we present an attempt to connect physical forcing to biogeochemical functioning of this coastal ecosystem. An array of stations, located in the lagoonal channel as well as in several bays under anthropogenic influence, was sampled during three cruises. We then tested the statistical relationships between the distribution of flushing indices and those of biological and chemical variables. Among the variables tested, silicate, chlorophyll a and bacterial biomass production present the highest correlations with flushing indices. Correlations are higher with local e-flushing times than with flushing lags or the sum of these two indices. In the bays, these variables often deviate from the relationships determined in the main lagoon channel. In the three bays receiving significant riverine inputs, silicate is well above the regression line, whereas data from the bay receiving almost insignificant freshwater inputs generally fit the lagoon channel regressions. Moreover, in the three bays receiving important urban and industrial effluents, chlorophyll a and bacterial production of biomass generally display values exceeding the lagoon channel regression trends whereas in the bay under moderate anthropogenic influence values follow the regressions obtained in the lagoon channel. The South West lagoon of New Caledonia can hence be viewed as a coastal mesotrophic ecosystem that is flushed by oligotrophic oceanic waters which subsequently replace the lagoonal waters with water considerably impoverished in resources for microbial growth. This flushing was high enough during the periods of study to influence the distribution of phytoplankton biomass, bacterial production of biomass and silicate concentrations in the lagoon channel as well as in some of the bay areas.

Earth Observations taken by the Expedition 13 crew

NASA Image and Video Library

2006-09-04

ISS013-E-76441 (4 Sept. 2006) --- Aquaculture in the Nile delta, Egypt is featured in this image photographed by an Expedition 13 crewmember on the International Space Station. In the last three decades, a series of lagoons and lakes with greater and lesser connection to the sea have been greatly modified for the production of fish along the northeast coast of the Nile delta. Partial sunglint in this image reveals numerous details in one such fishery. Waves generated by northwesterly winds (lower left to upper right) have generated the frond-like sand spit along the coast (top). Faint sea swells are visible at upper left. Dark patches in the center are shadows cast by small clouds (also visible as dull white masses against the silver-grey sunglint). Dark curved lines on the inshore (western) side of the spit show prior positions of the spit. Most of Musallas Lagoon occupies the lower half of the image. By contrast with spit, the shores of the lagoon are everywhere occupied by a network of man-made structures--mainly short dikes enclosing hundreds of aquaculture ponds. The total area under fish production is estimated to be 8,000 hectares in the lagoon, which provides more than half of the aquaculture production for Egypt, largely in the form of two species of mullet. An outlet to the Mediterranean Sea (top right), allows sea-water recharge to the lagoon. Wind helps to circulate the water in this shallow lagoon--bright wind streaks on the lagoon (lower left) show this circulation driven by the north-northwest wind on this day.

Microfacies and depositional environments of the Late Ordovician Lianglitage Formation at the Tazhong Uplift in the Tarim Basin of Northwest China

NASA Astrophysics Data System (ADS)

Gao, Da; Lin, Changsong; Yang, Haijun; Zuo, Fanfan; Cai, Zhenzhong; Zhang, Lijuan; Liu, Jingyan; Li, Hong

2014-04-01

The Late Ordovician Lianglitage Formation comprises 13 microfacies (Mf1-Mf13) that were deposited on a carbonate platform at the Tazhong Uplift of the Tarim Basin in Northwest China. Each type of microfacies indicates a specific depositional environment with a certain level of wave energy. Four primary groups of microfacies associations (MA1-MA4) were determined. These associations represent different depositional facies, including reef-shoal facies in the platform margin (MA1), carbonate sand shoal facies (MA2) and oncoid shoal (MA3) on open platforms, and lagoon and tidal flat facies (MA4) in the platform interior. Each microfacies association was generated in a fourth-order sedimentary sequence developing within third-order sequences (SQ1, SQ2, and SQ3, from bottom to top), showing a shallowing-upward trend. High-frequency sequences and facies correlation between wells suggests that the reef-shoal facies more successively developed in the southeastern part of the platform margin, and high-energy microfacies were more strictly confined by the top boundary of fourth-order sequences in the northwestern part of the platform. The highstand systems tract (HST) of the SQ2 is characterized by reef-shoals that developed along the platform margin and tidal flats and lagoons that developed in the platform interior, while the SQ3 is characterized by the oncoid shoal facies that generally developed on the uplift due to a regionally extensive transgression that occurred during the latter part of the Late Ordovician. The results of this study can be used for investigating the development and distribution of potential reservoirs; the reservoirs in southeastern part of the platform margin may be of premium quality because the high-energy microfacies were best preserved there.

Oolite facies as a transitional unit in deepening-upward carbonate sequences in Atoll, Seamount, and Guyot settings in Pacific basin

DOE Office of Scientific and Technical Information (OSTI.GOV)

Schlanger, S.O.

Prior to 1968, ooids had not been described from shallow-water carbonate complexes deposited in atoll, seamount, or guyot settings in the Pacific basin. This apparent lack of an oolite facies in the Pacific was puzzling, considering the abundance of ooids in modern Bahamian settings and in the Phanerozoic record in general. Since 1968, Deep Sea Drilling Project operations, marine seismic stratigraphic studies, dredging on drowned atolls, and field studies of an emergent atoll have revealed the presence of a Cretaceous oolite limestone atop Ita Maitai Guyot, Paleocene ooids on Koko Seamount, late Paleocene to middle Eocene ooids on Ojin Seamount,more » Eocene ooids on Harrie Guyot, and Holocene oolite limestone on Malden Island. At Ita Maitai Guyot the oolite limestone overlies normal lagoon sediments and is overlain by deep-water pelagic carbonate. At Malden Island, which is an emergent atoll, 3550-year-old oolite limestone overlies a 125,000-year-old reef complex. At Harrie Guyot and at Koko and Ojin Seamounts, ooids are associated with drowned atoll reef and lagoon complexes. The paleolatitude of deposition of the oolite facies lay between 5/sup 0/S and 18/sup 0/N. In these settings the formation of the oolite facies was apparently related to a rapid rise in sea level that caused flooding of an antecedent reef complex which failed to keep up with the rise in sea level. In Pacific basin environments the oolite facies is a minor and temporally ephemeral one which accounts for its scarcity in the stratigraphic record from this region.« less

Response of herbivore functional groups to sequential perturbations in Moorea, French Polynesia

NASA Astrophysics Data System (ADS)

Han, Xueying; Adam, Thomas C.; Schmitt, Russell J.; Brooks, Andrew J.; Holbrook, Sally J.

2016-09-01

The reefs surrounding the island of Moorea, French Polynesia, experienced two large pulse perturbations between 2008 and 2010, an outbreak of the crown-of-thorns seastar ( Acanthaster planci) followed by a cyclone, that resulted in the reduction in live coral cover on the fore reef from ~40 to <5 %. Live coral cover in back reef and fringing reef habitats initially remained relatively stable, but began a gradual decline around 2010. We assessed the changes in the functional composition of the herbivorous fish community following the pulse perturbations and during the time of gradual coral decline on the back reef and fringing reef. Forty-nine species of herbivorous fishes quantified in yearly surveys between 2006 and 2014 were assigned to six functional groups: browser, detritivore, excavator, farmer, grazer/detritivore, and scraper. Non-metric multidimensional scaling analyses revealed that despite unique functional assemblages initially existing among the fringing reef, back reef, and fore reef habitats, the herbivorous fish communities in all three habitats responded in a qualitatively similar fashion to coral decline by moving toward functional communities characterized by an increased representation of excavators and scrapers. Island-wide scraper biomass increased by ~sevenfold in the post-disturbance time period, while excavator biomass increased by nearly threefold. The biomass of detritivores and grazers/detritivores also increased over the same time period, but to a much lesser degree, while the biomass of browsers and farmers remained essentially unchanged. Macroalgae remained a relatively minor space holder (<10 % cover) in lagoon habitats and on the fore reef through 2014, enabling recruitment of juvenile coral and initiating coral recovery on the fore reef. Results suggest that a functional community with a substantial biomass of herbivores and the capacity for the biomass of scrapers and excavators to increase rapidly in response to landscape-scale declines in coral cover may enhance resilience by preventing the widespread establishment of macroalgae.

Changes in coral-reef structure through the Miocene in the Mediterranean province: Adaptive versus environmental influence

NASA Astrophysics Data System (ADS)

Pomar, Luis; Hallock, Pamela

2007-10-01

Well-documented Mediterranean examples of Miocene carbonate platforms, with complete exposures from shallow-water to basinal facies, provide evidence for temporal changes in reef-building capacity of zooxanthellate corals. In pre-late Tortonian platforms, small coralgal patches and mounds occur from platform top to the toe of slope, but they did not build to sea level. In contrast, barrier reefs with unequivocal reef-crest structures that reached sea level are documented in late Tortonian-early Messinian platforms. We suggest that a change in both calcification rates and bathymetric zonation was the result of coevolution of corals and Symbiodinium zooxanthellae, coeval to global cooling and, at least at a regional scale, a geochemical change that supported widespread aragonite precipitation through the late Miocene.

Yellow band disease compromises the reproductive output of the Caribbean reef-building coral Montastraea faveolata (Anthozoa, Scleractinia).

PubMed

Weil, Ernesto; Cróquer, Aldo; Urreiztieta, Isabel

2009-11-16

Sexual reproduction is critical to coral population dynamics and the long-term regeneration of coral reefs. Bleaching, disease, and/or anthropogenic-induced tissue/colony loss reduce reproductive output. This is the first attempt to explore the effect of a biotic disease on the reproduction of scleractinian corals. The study aimed to assess the effect of yellow band disease (YBD) on the reproduction of the important Caribbean reef-builder Montastraea faveolata. Tissue samples were collected from diseased, transition, and healthy-looking areas in each of 5 infected colonies and from 5 healthy controls in southwest Puerto Rico. The effect of disease-induced mortality was assessed by collecting samples from the edge and center of surviving small and large, healthy-looking tissue patches from large, previously infected tagged colonies. Fecundity was significantly lower in disease lesions compared to transition and healthy-looking tissues and the controls (99% fewer eggs). Fecundity in transition areas was significantly lower (50%) than in healthy-looking tissues in diseased colonies, which had 23% lower fecundity than control tissues. Although this fecundity drop was not statistically significant, it could indicate a systemic effect of YBD across the colony. Large and small patches had 64 and 84% fewer eggs than controls, respectively, and edge polyps had 97% fewer eggs than those in central control areas. Field observations of the spawning behavior of each tissue area corroborated the histological results. Our results indicate that YBD significantly compromises the reproductive output of M. faveolata, potentially reducing the fitness and consequently, the recovery of this important reef-building species on Caribbean coral reefs.

Model of a coral reef ecosystem

NASA Astrophysics Data System (ADS)

Atkinson, Marlin J.; Grigg, Richard W.

1984-08-01

The ECOPATH model for French Frigate Shoals estimates the benthic plant production (net primary production in kg wet weight) required to support the atoll food chain. In this section we estimate the benthic net primary production and net community production of the atoll based on metabolism studies of reef flat, knolls, and lagoon communities at French Frigate Shoals Hawaii. Community metabolism was measured during winter and summer. The reef communities at French Frigate Shoals exhibited patterns and rates of organic carbon production and calcification similar to other reefs in the world. The estimate of net primary production is 6.1·106 kg wet weight km-2 year-1±50%, a value remarkably close to the estimate by the ECOPATH model of 4.3·106 kg wet weight km-2 year-1. Our estimate of net community production or the amount of carbon not consumed by the benthos was high; approximately 15% of the net primary production. Model results indicate that about 5% of net primary production is passed up the food chain to mobile predators. This suggests about 10% of net primary production (˜6% of gross primary production) may be permanently lost to the system via sediment burial or export offshore.

Holocene key coral species in the Northwest Pacific: indicators of reef formation and reef ecosystem responses to global climate change and anthropogenic stresses in the near future

NASA Astrophysics Data System (ADS)

Hongo, Chuki

2012-03-01

The geological record of key coral species that contribute to reef formation and maintenance of reef ecosystems is important for understanding the ecosystem response to global-scale climate change and anthropogenic stresses in the near future. Future responses can be predicted from accumulated data on Holocene reef species identified in drillcore and from data on raised reef terraces. The present study analyzes a dataset based on 27 drillcores, raised reef terraces, and 134 radiocarbon and U-Th ages from reefs of the Northwest Pacific, with the aim of examining the role of key coral species in reef growth and maintenance for reef ecosystem during Holocene sea-level change. The results indicate a latitudinal change in key coral species: arborescent Acropora (Acropora intermedia and Acropora muricata) was the dominant reef builder at reef crests in the tropics, whereas Porites (Porites australiensis, Porites lutea, and Porites lobata) was the dominant contributor to reef growth in the subtropics between 10,000 and 7000 cal. years BP (when the rate of sea-level rise was 10 m/ka). Acropora digitifera, Acropora hyacinthus, Acropora robusta/A. abrotanoides, Isopora palifera, Favia stelligera, and Goniastrea retiformis from the corymbose and tabular Acropora facies were the main key coral species at reef crests between 7000 and 5000 cal. years BP (when the rate of sea-level rise was 5 m/ka) and during the following period of stable sea-level. Massive Porites (P. australiensis, P. lutea, and P. lobata) contributed to reef growth in shallow lagoons during the period of stable sea level. Key coral species from the corymbose and tabular Acropora facies have the potential to build reefs and maintain ecosystems in the near future under a global sea-level rise of 2-6 m/ka, as do key coral species from the arborescent Acropora facies and massive Porites facies, which show vigorous growth and are tolerant to relatively deep-water, low-energy environments. However, these species are likely to experience severe mortality in upcoming decades due to natural and anthropogenic stresses. Consequently, this damage will lead to a collapse in reef formation and the maintenance of reef ecosystems in the near future. This study emphasizes the need for research into the conservation of key coral species.

Relative Importance of Coral Cover, Habitat Complexity and Diversity in Determining the Structure of Reef Fish Communities

PubMed Central

Komyakova, Valeriya; Munday, Philip L.; Jones, Geoffrey P.

2013-01-01

The structure of coral reef habitat has a pronounced influence on the diversity, composition and abundance of reef-associated fishes. However, the particular features of the habitat that are most critical are not always known. Coral habitats can vary in many characteristics, notably live coral cover, topographic complexity and coral diversity, but the relative effects of these habitat characteristics are often not distinguished. Here, we investigate the strength of the relationships between these habitat features and local fish diversity, abundance and community structure in the lagoon of Lizard Island, Great Barrier Reef. In a spatial comparison using sixty-six 2m2 quadrats, fish species richness, total abundance and community structure were examined in relation to a wide range of habitat variables, including topographic complexity, habitat diversity, coral diversity, coral species richness, hard coral cover, branching coral cover and the cover of corymbose corals. Fish species richness and total abundance were strongly associated with coral species richness and cover, but only weakly associated with topographic complexity. Regression tree analysis showed that coral species richness accounted for most of the variation in fish species richness (63.6%), while hard coral cover explained more variation in total fish abundance (17.4%), than any other variable. In contrast, topographic complexity accounted for little spatial variation in reef fish assemblages. In degrading coral reef environments, the potential effects of loss of coral cover and topographic complexity are often emphasized, but these findings suggest that reduced coral biodiversity may ultimately have an equal, or greater, impact on reef-associated fish communities. PMID:24349455

Relative importance of coral cover, habitat complexity and diversity in determining the structure of reef fish communities.

PubMed

Komyakova, Valeriya; Munday, Philip L; Jones, Geoffrey P

2013-01-01

The structure of coral reef habitat has a pronounced influence on the diversity, composition and abundance of reef-associated fishes. However, the particular features of the habitat that are most critical are not always known. Coral habitats can vary in many characteristics, notably live coral cover, topographic complexity and coral diversity, but the relative effects of these habitat characteristics are often not distinguished. Here, we investigate the strength of the relationships between these habitat features and local fish diversity, abundance and community structure in the lagoon of Lizard Island, Great Barrier Reef. In a spatial comparison using sixty-six 2m(2) quadrats, fish species richness, total abundance and community structure were examined in relation to a wide range of habitat variables, including topographic complexity, habitat diversity, coral diversity, coral species richness, hard coral cover, branching coral cover and the cover of corymbose corals. Fish species richness and total abundance were strongly associated with coral species richness and cover, but only weakly associated with topographic complexity. Regression tree analysis showed that coral species richness accounted for most of the variation in fish species richness (63.6%), while hard coral cover explained more variation in total fish abundance (17.4%), than any other variable. In contrast, topographic complexity accounted for little spatial variation in reef fish assemblages. In degrading coral reef environments, the potential effects of loss of coral cover and topographic complexity are often emphasized, but these findings suggest that reduced coral biodiversity may ultimately have an equal, or greater, impact on reef-associated fish communities.

Age and microfacies of oceanic Upper Triassic radiolarite components from the Middle Jurassic ophiolitic mélange in the Zlatibor Mountains (Inner Dinarides, Serbia) and their provenance

NASA Astrophysics Data System (ADS)

Gawlick, Hans-Jürgen; Djerić, Nevenka; Missoni, Sigrid; Bragin, Nikita Yu.; Lein, Richard; Sudar, Milan; Jovanović, Divna

2017-08-01

Oceanic radiolarite components from the Middle Jurassic ophiolitic mélange between Trnava and Rožanstvo in the Zlatibor Mountains (Dinaridic Ophiolite Belt) west of the Drina-Ivanjica unit yield Late Triassic radiolarian ages. The microfacies characteristics of the radiolarites show pure ribbon radiolarites without crinoids or thin-shelled bivalves. Beside their age and the preservation of the radiolarians this points to a deposition of the radiolarites on top of the oceanic crust of the Neo-Tethys, which started to open in the Late Anisian. South of the study area the ophiolitic mélange (Gostilje-Ljubiš-Visoka-Radoševo mélange) contains a mixture of blocks of 1) oceanic crust, 2) Middle and Upper Triassic ribbon radiolarites, and 3) open marine limestones from the continental slope. On the basis of this composition we can conclude that the Upper Triassic radiolarite clasts derive either from 1) the younger parts of the sedimentary succession above the oceanic crust near the continental slope or, more convincingly 2) the sedimentary cover of ophiolites in a higher nappe position, because Upper Triassic ribbon radiolarites are only expected in more distal oceanic areas. The ophiolitic mélange in the study area overlies different carbonate blocks of an underlying carbonate-clastic mélange (Sirogojno mélange). We date and describe three localities with different Upper Triassic radiolarite clasts in a mélange, which occurs A) on top of Upper Triassic fore-reef to reefal limestones (Dachstein reef), B) between an Upper Triassic reefal limestone block and a Lower Carnian reef limestone (Wetterstein reef), and C) in fissures of an Upper Triassic lagoonal to back-reef limestone (Dachstein lagoon). The sedimentary features point to a sedimentary and not to a tectonic emplacement of the ophiolitic mélange (= sedimentary mélange) filling the rough topography of the topmost carbonate-clastic mélange below. The block spectrum of the underlying and slightly older carbonate-clastic mélange points to a deposition of the sedimentary ophiolitic mélange east of or on top of the Drina-Ivanjica unit.

[Structure of reef fish communities in Catalinas Islands and Ocotal beach, North Pacific of Costa Rica].

PubMed

Espinoza, Mario; Salas, Eva

2005-01-01

The reefs are heterogeneous systems that maintain a high diversity of organisms. Fish community structure varies within and among reefs, so it would be expected that reef structure and heterogeneity should affect fish communities inhabiting reefs. Four reef patches at Catalinas Islands (Sur, La Pared, Roca Sucia and Sombrero) and one in Ocotal beach (10 degrees 28'45" N; 85 degrees 52'35" W) were studied with visual censuses (July-December 2003). The structure and composition of fishes between Catalinas islands and Ocotal beach were different, and habitat structure and composition explain most of the variance founded. The presence of the fleshy algae Caulerpa sertularioides in Ocotal, and the corals Tubastrea coccinea and Pocillopora spp. at Catalinas Island explained the variability among sites and how it affected fish community structure and composition. The butterfly fish Johnrandallia nigrirostris, damselfish Microspathodon dorsalis, and surgeon fish Prionurus punctatus were directly correlated with the ahermatipic coral Tubastrea coccinea in Roca Sucia reef, while the angel fish Holacanthus passer was associated to reefs with a major percentage of rocky substrate. Other species such as the damselfish Abudefduf troschelli and Halichoeres dispilus were more abundant at Ocotal, where the algae C sertularioides dominated. The number and abundance of reef fishes was directly correlated with the rugosity index at the reefs of Roca Sucia and Ocotal, but not at reefs of La Pared and Sombrero.

Subterranean Groundwater Nutrient Input to Coastal Oceans and Coral Reef Sustainability

NASA Astrophysics Data System (ADS)

Paytan, A.; Street, J. H.

2003-12-01

Coral reefs are often referred to as the tropical rain forests of the oceans because of their high productivity and biodiversity. Recent observations in coral reefs worldwide have shown clear degradation in water quality and coral reef health and diversity. The implications of this are severe, including tremendous economic losses mostly though fishing and tourism. Nutrient loading has been implicated as one possible cause for the ecosystem decline. A previously unappreciated potential source of nutrient loading is submarine ground water discharge (SGW). Ground water in many cases has high nutrient content from sewage pollution and fertilizer application for agriculture and landscaping. To better understand the effect of this potential source of nutrient input and degrading water quality, we are exploring the contribution of SGW to the nutrient levels in coral reefs. A key to this approach is determining the amount and source of SGW that flows into the coast as well as its nutrient concentrations. The SGW flux and associated input of chemical dissolved load (nutrient, DOC, trace elements and other contaminants) is quantified using naturally occurring Ra isotopes. Radium isotopes have been shown to be excellent tracers for SGW inputs into estuaries and coastal areas (Moore, 1996; Hussain et al., 1999; Kerst et al., 2000). Measurements of Ra activity within the coral reef, the lagoons and the open waters adjacent to the reef provide valuable information regarding the input of Ra as well as nutrients and possibly pollutant from groundwater discharge. Through this analysis the effect of SGD on the delicate carbon and nutrient balance of the fragile coral reef ecosystem could be evaluated. In addition to quantifying the contribution of freshwater to the nutrient mass balance in the reef, information regarding the length of time a water parcel has remained in the near-shore region over the reef can be estimated using the Ra isotope quartet.

Sediment characteristics and water quality in the two hyper-saline lagoons along the Red Sea coast of Saudi Arabia

NASA Astrophysics Data System (ADS)

Rasul, Najeeb; Al-Farawati, Radwan; Al-Harbi, Omer; Naser Qutub, Abdul

2013-04-01

The two hyper-saline Shoaiba lagoons, Khawr ash Shaibah al Masdudah (northern lagoon) and Khawr ash Shaibah al Maftuhah (southern lagoon) have a unique environmental set-up because no rivers or wadis flow into the lagoons and therefore detrital material to the lagoons is lacking and most of the sediments are indigenous carbonates. The biogenic material is mostly derived from coral debris, coralline algae and molluscs abundant in gravel and sand size fractions. The evaporite deposits from the adjoining sabkhas are transported to the lagoon during tidal cycles. Carbonate is abundant in the form of aragonite and High Mg-calcite indicating carbonate to be recent and formed under shallow water conditions. In general, the sediments are the result of the mechanical breakdown of molluscs and coral reefs by either human activity or by coral boring marine organisms and physical processes such as tidal and wind generated currents. Strong currents dominate only the deeper part at the entrance of the lagoons that causes the winnowing of the finer sediments, and its transportation during flooding and ebbing. Shallow depths averaging 3 m, wind and tidal stirring are the main forces preventing the lagoons from developing stratification resulting in a well-mixed body of water. The shallow depth of the lagoons keep the turbidity levels higher, whereas salinity as high as 52 ‰ and water temperature as high as 38 °C helps in the formation of halite at the periphery. The cyclical inundation of sabkhas by a thin sheet of water during tidal cycles is important in understanding the ecological consequence. Mangrove stands in the lagoons act as a source of nutrients to the flora and fauna inhabiting the lagoons. The configurations of the mouth of the lagoons influence the tidal currents, including the sediment and water movement. The tidal current is enhanced as it enters the lagoons, in response to the funneling effect caused by the narrow channel. The current diffuses as the entrance widens. In the case of Khawr ash Shaibah al Masdudah the mouth is wide and it faces the open sea directly, whereas the mouth of Khawr ash Shaibah al Maftuhah, although narrower, the tidal current is only strong until the channel to the lagoon bends almost 90° where the tidal current dissipates, resulting in the restricted water and sediment movement in the lagoon. The coarser sediments are stained gray-black because of a reducing environment and formation of authigenic pyrite. Stagnant condition prevails inside the lagoons because of insufficient exchange of water with the open sea and lack of rainfall causes hyper-saline conditions. Higher salinity values were evident in the shallow waters, whereas oxygen saturation ranged between 77 % (southern lagoon) and 107 % (northern lagoon) which could be attributed to the complex nature of the southern lagoon. Reactive phosphate and nitrite concentrations in the surface waters were low and in many locations under the detection limit reflecting the oligotrophic behaviour of the Red Sea and limited supply of nutrients from adjacent areas. There is an abundant presence of trace metals especially in fine sediments that has the tendency to adsorb the metals more efficiently. There is an inverse correlation between heavy metals and carbonate content in the sediments, and much stronger particularly with Cr, V and Co. The Landsat ETM identifies two depth zones in the lagoons and shows the effects of the influence of flooding and ebbing on the sediment distribution and the extent of the water cover seasonally.

Relevance of cryptic fishes in biodiversity assessments: A case study at Buck Island Reef National Monument, St. Croix

USGS Publications Warehouse

Smith-Vaniz, W.F.; Jelks, H.L.; Rocha, L.A.

2006-01-01

Because cryptic fishes are difficult to accurately survey, they are undersampled components of coral reef habitats, and their ecological roles have been generally ignored. Fifty-eight enclosed stations were sampled in shoreline, nearshore reef, lagoon, backreef, forereef, and bank/shelf habitats with an ichthyocide (rotenone) at Buck Island Reef National Monument, St. Croix, U.S. Virgin Islands. Our samples included 55 families and 228 species, 60 previously unreported from St. Croix. Fish assemblages varied across habitat zones with the shoreline assemblage the most distinct. Only 8% of the species were present in all habitats. Multi-dimensional scaling plots of habitat characteristics and Bray-Curtis similarities of fish assemblages revealed similar patterns. Dominant and rare taxa are enumerated for each habitat sampled. Rotenone and visual census data are compared. While visual surveys accumulated more species per unit of effort, rotenone samples accumulated more species by area. Only 36% of the 228 species sampled with rotenone were visually detected, while 70% of the 115 species visually detected were also collected with rotenone. The use of rotenone is controversial but important for obtaining reasonably complete inventories of reef fishes. Misconceptions about rotenone and the advantages and limitations of alternative biodiversity assessment methods are discussed. ?? 2006 Rosenstiel School of Marine and Atmospheric Science of the University of Miami.

Species co-occurrence affects the trophic interactions of two juvenile reef shark species in tropical lagoon nurseries in Moorea (French Polynesia).

PubMed

Matich, Philip; Kiszka, Jeremy J; Mourier, Johann; Planes, Serge; Heithaus, Michael R

2017-06-01

Food web structure is shaped by interactions within and across trophic levels. As such, understanding how the presence and absence of predators, prey, and competitors affect species foraging patterns is important for predicting the consequences of changes in species abundances, distributions, and behaviors. Here, we used plasma δ 13 C and δ 15 N values from juvenile blacktip reef sharks (Carcharhinus melanopterus) and juvenile sicklefin lemon sharks (Negaprion acutidens) to investigate how species co-occurrence affects their trophic interactions in littoral waters of Moorea, French Polynesia. Co-occurrence led to isotopic niche partitioning among sharks within nurseries, with significant increases in δ 15 N values among sicklefin lemon sharks, and significant decreases in δ 15 N among blacktip reef sharks. Niche segregation likely promotes coexistence of these two predators during early years of growth and development, but data do not suggest coexistence affects life history traits, such as body size, body condition, and ontogenetic niche shifts. Plasticity in trophic niches among juvenile blacktip reef sharks and sicklefin lemon sharks also suggests these predators are able to account for changes in community structure, resource availability, and intra-guild competition, and may fill similar functional roles in the absence of the other species, which is important as environmental change and human impacts persist in coral reef ecosystems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Habitat degradation is threatening reef replenishment by making fish fearless.

PubMed

Lönnstedt, Oona M; McCormick, Mark I; Chivers, Douglas P; Ferrari, Maud C O

2014-09-01

Habitat degradation is one of the 'Big Five' drivers of biodiversity loss. However, the mechanisms responsible for this progressive loss of biodiversity are poorly understood. In marine ecosystems, corals play the role of ecosystem engineers, providing essential habitat for hundreds of thousands of species and hence their health is crucial to the stability of the whole ecosystem. Climate change is causing coral bleaching and degradation, and while this has been known for a while, little do we know about the cascading consequences of these events on the complex interrelationships between predators and their prey. The goal of our study was to investigate, under completely natural conditions, the effect of coral degradation on predator-prey interactions. Settlement stage ambon damselfish (Pomacentrus amboinensis), a common tropical fish, were released on patches of healthy or dead corals, and their behaviours in situ were measured, along with their response to injured conspecific cues, a common risk indicator. This study also explored the effect of habitat degradation on natural levels of mortality at a critical life-history transition. We found that juveniles in dead corals displayed risk-prone behaviours, sitting further away and higher up on the reef patch, and failed to respond to predation cues, compared to those on live coral patches. In addition, in situ survival experiments over 48 h indicated that juveniles on dead coral habitats had a 75% increase in predation-related mortality, compared to fish released on live, healthy coral habitats. Our results provide the first of many potential mechanisms through which habitat degradation can impact the relationship between prey and predators in the coral reef ecosystem. As the proportion of dead coral increases, the recruitment and replenishment of coral reef fishes will be threatened, and so will the level of diversity in these biodiversity hot spots. © 2014 The Authors. Journal of Animal Ecology © 2014 British Ecological Society.

Soft coral abundance on the central Great Barrier Reef: effects of Acanthaster planci, space availability, and aspects of the physical environment

NASA Astrophysics Data System (ADS)

Fabricius, K. E.

1997-07-01

The distribution and abundance of soft coral genera on reefs of the central Great Barrier Reef was investigated in relation to reef position, recent history of disturbance, wave exposure, substratum slope and depth. Eighty-five 25 m long transects were surveyed at 10 m depth on windward sides of 14 mid- and outer-shelf reefs. A further 75 transects in different zones on one mid-shelf reef (Davies Reef) between 5 and 30 m depth were investigated. The crown-of-thorns starfish Acanthaster planci had caused large-scale mortality of scleractinians on eight of these reefs five to ten years prior to the study, and as a result, scleractinian cover was only 35-55% of that on the six unimpacted reefs. On the impacted reefs, stony corals with massive and encrusting growths form had smaller average colony diameters but similar or slightly lower numerical abundance. In contrast, mean colony size, cover and abundance of branching stony corals showed no difference between impacted and unimpacted reefs. Twenty-four genera of soft corals (in eight families) were recorded, and none showed different abundance or cover in areas of former A. planci impact, compared to unaffected sites. Similarly, no difference was detected among locations in the numbers or area cover of sponges, tunicates, zoanthids, Halimeda or other macro-algae. Mean soft coral cover was 2 to 5% at 10 m on sheltered mid-shelf reefs, and 12 to 17% on more current-exposed reefs. Highest cover and abundances generally occurred on platforms of outer-shelf reefs exposed to relatively strong currents but low wave energy. On Davies Reef, cover and colony numbers of the families Nephtheidae and Xeniidae were low within the zone of wave impact, in flow-protected bays and lagoons, on shaded steep slopes, and at depths above 10 and below 25 m. In contrast, distributions of genera of the family Alcyoniidae were not related to these physical parameters. The physical conditions of a large proportion of habitats appear "sub-optimal" for the fastest growing taxa, possibly preventing an invasion of the cleared space. Thus, in the absence of additional stress these shallow-water fore-reef zones appear sufficiently resilient to return to their pre-outbreak state of scleractinian dominance.

Resolving high-frequency internal waves generated at an isolated coral atoll using an unstructured grid ocean model

NASA Astrophysics Data System (ADS)

Rayson, Matthew D.; Ivey, Gregory N.; Jones, Nicole L.; Fringer, Oliver B.

2018-02-01

We apply the unstructured grid hydrodynamic model SUNTANS to investigate the internal wave dynamics around Scott Reef, Western Australia, an isolated coral reef atoll located on the edge of the continental shelf in water depths of 500,m and more. The atoll is subject to strong semi-diurnal tidal forcing and consists of two relatively shallow lagoons separated by a 500 m deep, 2 km wide and 15 km long channel. We focus on the dynamics in this channel as the internal tide-driven flow and resulting mixing is thought to be a key mechanism controlling heat and nutrient fluxes into the reef lagoons. We use an unstructured grid to discretise the domain and capture both the complex topography and the range of internal wave length scales in the channel flow. The model internal wave field shows super-tidal frequency lee waves generated by the combination of the steep channel topography and strong tidal flow. We evaluate the model performance using observations of velocity and temperature from two through water-column moorings in the channel separating the two reefs. Three different global ocean state estimate datasets (global HYCOM, CSIRO Bluelink, CSIRO climatology atlas) were used to provide the model initial and boundary conditions, and the model outputs from each were evaluated against the field observations. The scenario incorporating the CSIRO Bluelink data performed best in terms of through-water column Murphy skill scores of water temperature and eastward velocity variability in the channel. The model captures the observed vertical structure of the tidal (M2) and super-tidal (M4) frequency temperature and velocity oscillations. The model also predicts the direction and magnitude of the M2 internal tide energy flux. An energy analysis reveals a net convergence of the M2 energy flux and a divergence of the M4 energy flux in the channel, indicating the channel is a region of either energy transfer to higher frequencies or energy loss to dissipation. This conclusion is supported by the mooring observations that reveal high frequency lee waves breaking on the turning phase of the tide.

Multi-scale interactions between local hydrography, seabed topography, and community assembly on cold-water coral reefs

NASA Astrophysics Data System (ADS)

Henry, L.-A.; Moreno Navas, J.; Roberts, J. M.

2013-04-01

We investigated how interactions between hydrography, topography and species ecology influence the assembly of species and functional traits across multiple spatial scales of a cold-water coral reef seascape. In a novel approach for these ecosystems, we used a spatially resolved complex three-dimensional flow model of hydrography to help explain assembly patterns. Forward-selection of distance-based Moran's eigenvector mapping (dbMEM) variables identified two submodels of spatial scales at which communities change: broad-scale (across reef) and fine-scale (within reef). Variance partitioning identified bathymetric and hydrographic gradients important in creating broad-scale assembly of species and traits. In contrast, fine-scale assembly was related more to processes that created spatially autocorrelated patches of fauna, such as philopatric recruitment in sessile fauna, and social interactions and food supply in scavenging detritivores and mobile predators. Our study shows how habitat modification of reef connectivity and hydrography by bottom fishing and renewable energy installations could alter the structure and function of an entire cold-water coral reef seascape.

A Multi-Sensor Approach to Enhance the Prediction of Mangrove Biophysical Characteristics in Chilika Lagoon and Bhitarkanika Wildlife Sanctuary, Odisha, India

NASA Astrophysics Data System (ADS)

Kumar, A.; Bledsoe, R.; Mishra, D. R.; Cameron, C.; Dahal, S.; Remillard, C.; Stone, A.; Stupp, P.

2017-12-01

Mangroves, one of the most productive ecosystems on Earth, play a major role in coastal ecosystem processes from mitigating erosion to acting as a barrier against tidal and storm surges associated with tropical cyclones. India has about 5 % of the world's mangrove vegetation, and over half of which is found along the east coast of the country. Chilika Lagoon and Bhitarkanika Wildlife Sanctuary are Ramsar sites of international wetland importance, situated in the state of Odisha along the east coast of India. Chilika Lagoon holds three small, but distinct mangrove patches, while Bhitarkanika Wildlife Sanctuary has several large, dense patches of mangroves. There is growing concern for the effective management and conservation of these mangrove forests. This study demonstrated the use of a suite of satellite data (Terra, Landsat, and Sentinel-1) for meeting the following objectives: 1. Derive a long-term spatio-temporal phenological maps of the biophysical parameters (chlorophyll, leaf area index, gross primary productivity, and evapotranspiration); 2. Analyze long-term spatio-temporal variability of physical and meteorological parameters; 3. Document decadal changes in mangroves area estimates starting from 1995 to 2017 using Landsat and radar data. The time series developed in this study revealed a phenological pattern for mangrove biophysical characteristics. Historical analysis of land cover maps indicated decrease in dense mangrove area and increase in open mangrove area and fragmentation. The results of this study will be used as an efficient biophysical mapping and monitoring protocol for mangrove forests in restoration decision-making.

Hg concentrations and related risk assessment in coral reef crustaceans, molluscs and fish from New Caledonia.

PubMed

Chouvelon, Tiphaine; Warnau, Michel; Churlaud, Carine; Bustamante, Paco

2009-01-01

There is a dramatic lack of data on Hg levels in marine organisms from tropical areas, and in particular from New Caledonia. For the first time, this study reports the total Hg concentrations in the tissues of several marine taxa from the New Caledonian lagoon. Seafood from both wild and farmed populations was considered. Hg concentrations varied over three orders of magnitudes according to factors including species, age (size/weight), trophic level, lifestyle and geographical origin. Taking into account the edible tissues, estimations of the amount of flesh that should be consumed by a 60-kg person to reach the Hg Provisional Tolerable Weekly Intake (PTWI) reveal acceptable risk for Human health in general. However, a risk was clearly identified in one site of the lagoon (i.e. Grande Rade) where high Hg concentrations were measured. These concentrations were higher than values reported in the current literature.

Monitoring Biogeochemical Processes in Coral Reef Environments with Remote Sensing: A Cross-Disciplinary Approach.

NASA Astrophysics Data System (ADS)

Perez, D.; Phinn, S. R.; Roelfsema, C. M.; Shaw, E. C.; Johnston, L.; Iguel, J.; Camacho, R.

2017-12-01

Primary production and calcification are important to measure and monitor over time, because of their fundamental roles in the carbon cycling and accretion of habitat structure for reef ecosystems. However, monitoring biogeochemical processes in coastal environments has been difficult due to complications in resolving differences in water optical properties from biological productivity and other sources (sediment, dissolved organics, etc.). This complicates application of algorithms developed for satellite image data from open ocean conditions, and requires alternative approaches. This project applied a cross-disciplinary approach, using established methods for monitoring productivity in terrestrial environments to coral reef systems. Availability of regularly acquired high spatial (< 5m pixels), multispectral satellite imagery has improved mapping and monitoring capabilities for shallow, marine environments such as seagrass and coral reefs. There is potential to further develop optical models for remote sensing applications to estimate and monitor reef system processes, such as primary productivity and calcification. This project collected field measurements of spectral absorptance and primary productivity and calcification rates for two reef systems: Heron Reef, southern Great Barrier Reef and Saipan Lagoon, Commonwealth of the Northern Mariana Islands. Field data were used to parameterize a light-use efficiency (LUE) model, estimating productivity from absorbed photosynthetically active radiation. The LUE model has been successfully applied in terrestrial environments for the past 40 years, and could potentially be used in shallow, marine environments. The model was used in combination with a map of benthic community composition produced from objective based image analysis of WorldView 2 imagery. Light-use efficiency was measured for functional groups: coral, algae, seagrass, and sediment. However, LUE was overestimated for sediment, which led to overestimation of productivity for the mapped area. This was due to differences in spatial and temporal resolution of field data used in the model. The limitations and application of the LUE model to coral reef environments will be presented.

KSC-03pd1375

NASA Image and Video Library

2003-04-29

KENNEDY SPACE CENTER, FLA. - Onboard the Liberty Star, the NASA Space Shuttle support ship operated by United Space Alliance, .Dr. Grant Gilmore holds some of the equipment to be used on an undersea expedition. Gilmore is co-principle investigator of the Passive Acoustic Monitoring System (PAMS), part of the equipment. NASA/KSC is participating in the expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. Scientists on the team will be deploying an underwater robot, a seafloor sampler, and the PAMS, originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

Linking morphology to ecosystem structure using satellite for monitoring Wetlands

NASA Astrophysics Data System (ADS)

Filipponi, F.; Valentini, E.; Taramelli, A.; Giulio, S.; Persichillo, M.; D'Alpaos, A.

2013-12-01

Modern views on the behavior of complex systems, like the low lying coastal areas, allow the interpretation of phenomenological coastal landscape as a steady state that corresponds to a dynamic equilibrium, and to a self-organized exogenic order of the edge of the chaos. Space-borne data, coupled with field spectral measurements and observations, are quantitative tools for the research on feedbacks between the biological influences and physical forming processes steering landscape changes, allowing the identification of critical thresholds beyond which the ecosystem reach a new steady state. This research deals with a multi-temporal change analysis of halophytic vegetation and morphology of two analogous accumulation sites along the northern Adriatic adjoining coast: the 'Bacan island' (Venice Lagoon) and the Spit of Goro Lagoon (Po Delta). These two sites represent delicate ecosystems and are susceptible to different drivers being located close to the lagoon's inlet. The two tests sites support a great biodiversity and supply important resources, so the conservation of their habitats is necessary to maintain the ecosystem services provision. Evidence from previous studies highlights the role of climate, mostly winds and hydrology acting on sediment transport, but only few accounts for the role of vegetation in landform shaping and sediment stabilizing. In this study spatial trends of both vegetation cover/typology and sediment/soil distribution are implemented to obtain detailed classification from EO. By means of sub-pixel processing techniques (Spectral Mixing Analysis), classifications are analyzed in terms of spatial (Power law) and temporal (Empirical Orthogonal Functions) patterns, in order to find the fingerprint of spatial patterns of vegetation, sediments and very shallow waters and their variation over time. The application of a double step analysis from coarse to finer spatial resolution lead first to a biophysical cover map in term of vegetation typologies and cover percent, sediment typology and length of the different branches highlighting the mosaic of spatial pattern of vegetation, sediments and morphology. Then our results support the fact that the most frequent patch sizes, corresponding to the smallest vegetation patches as consistent with a power law relationship, are associated with the highest length values and specific sediments values; as the patch sizes become larger, and thus less frequent, the length next to patches decreases and reaches much lower values in relations to sediments classes. This indicates that at first, the formation of small vegetation patches increases flow resistance and facilitates the formation of new morphology; at the same time, when a threshold size is reached (due to patch growth or merging between adjacent patches), vegetation controls length of the different branches. In the framework of spatial self-organization, this method gives rise to a new approach to the study of landscape-forming processes, taking into account the prominent role of living organisms in shaping Earth's surface, in order to develop new instruments and tools that allow modular variation of spatial and temporal scales of observation (i.e. from local to regional; from seasonal to inter annual) that is mandatory for a valuable implementation of current management and conservation strategies (Integrated Coastal Zone Management).

GMT007_09_33_Terry Virts_India Maldives night zoom chennai colum

NASA Image and Video Library

2015-01-06

ISS042eE01551 (01/06/2015) --- NASA astronaut Terry Virts tweeted this night image out with the twinkling city lights of the coast of India and the Maldives. The Maldives is a tropical nation in the Indian Ocean composed of 26 coral atolls, which stretch for hundreds of islands. It’s known for its beaches, blue lagoons and extensive reefs. Terry tweeted this comment along with the image: " Moonlit clouds over southeast #India coastline, with Chennai, Bangalore, and Hyderabad."

[Changes in fish communities of coral reefs at Sabana-Camagüey Archipelago, Cuba].

PubMed

Claro, Rodolfo; Cantelar, Karel; Amargós, Fabián Pina; García-Arteaga, Juan P

2007-06-01

A comparison of fish community structure in the Sabana-Camagüey Archipelago (1988-1989 and 2000) using visual census surveys (eight belt transects 2x50 m in each site) suggests a notable decrease on species richness, and a two thirds reduction in fish density and biomass on coral reefs. This decrease in fish populations may be related to the alarming decrease of scleractinian coral cover, and an enormous proliferation of algae, which currently covers 70-80% of the hard substrate, impeding the recovery of corals and other benthic organisms. High coral mortalities occurred between the study periods, which correlate with the high temperatures caused by the ENSO events of 1995, 1997 and 1998. These events caused massive bleaching of corals and subsequent algae overgrowth. Evidence of nutrient enrichment from the inner lagoons and overfishing are also present. Collectively, these effects have provoked a marked degradation of reef habitats. These changes appear to have affected the availability of refuges and food for fishes, and may be constraining individual growth potential and population size.

Coastal nurseries and their importance for conservation of sea kraits.

PubMed

Bonnet, Xavier; Brischoux, François; Bonnet, Christophe; Plichon, Patrice; Fauvel, Thomas

2014-01-01

Destruction and pollution of coral reefs threaten these marine biodiversity hot stops which shelter more than two thirds of sea snake species. Notably, in many coral reef ecosystems of the Western Pacific Ocean, large populations of sea kraits (amphibious sea snakes) have drastically declined during the past three decades. Protecting remaining healthy populations is thus essential. In New Caledonia, coral reefs shelter numerous sea krait colonies spread throughout an immense lagoon (24,000 km2). Sea kraits feed on coral fish but lay their eggs on land. However, ecological information on reproduction and juveniles is extremely fragmentary, precluding protection of key habitats for reproduction. Our 10 years mark recapture study on Yellow sea kraits (L. saintgironsi >8,700 individuals marked) revealed that most neonates aggregate in highly localized coastal sites, where they feed and grow during several months before dispersal. Hundreds of females emigrate seasonally from remote populations (>50 km away) to lay their eggs in these coastal nurseries, and then return home. Protecting these nurseries is a priority to maintain recruitment rate, and to retain sea krait populations in the future.

Coastal Nurseries and Their Importance for Conservation of Sea Kraits

PubMed Central

Bonnet, Xavier; Brischoux, François; Bonnet, Christophe; Plichon, Patrice; Fauvel, Thomas

2014-01-01

Destruction and pollution of coral reefs threaten these marine biodiversity hot stops which shelter more than two thirds of sea snake species. Notably, in many coral reef ecosystems of the Western Pacific Ocean, large populations of sea kraits (amphibious sea snakes) have drastically declined during the past three decades. Protecting remaining healthy populations is thus essential. In New Caledonia, coral reefs shelter numerous sea krait colonies spread throughout an immense lagoon (24,000 km2). Sea kraits feed on coral fish but lay their eggs on land. However, ecological information on reproduction and juveniles is extremely fragmentary, precluding protection of key habitats for reproduction. Our 10 years mark recapture study on Yellow sea kraits (L. saintgironsi >8,700 individuals marked) revealed that most neonates aggregate in highly localized coastal sites, where they feed and grow during several months before dispersal. Hundreds of females emigrate seasonally from remote populations (>50 km away) to lay their eggs in these coastal nurseries, and then return home. Protecting these nurseries is a priority to maintain recruitment rate, and to retain sea krait populations in the future. PMID:24670985

Characterization and management of the commercial sector of the Pohnpei coral reef fishery, Micronesia

NASA Astrophysics Data System (ADS)

Rhodes, K. L.; Tupper, M. H.; Wichilmel, C. B.

2008-06-01

Commercial coral reef fisheries in Pohnpei (Micronesia) extract approximately 1,521 kg of reef fish daily (˜500 MT year-1) from 152 km2 of surrounding reef. More than 153 species were represented during surveys, with 25 species very common or common within combined-gear catch. Acanthurids contributed the greatest to catch volume, with bluespine unicornfish, Naso unicornis, and orangespine unicornfish, Naso lituratus, among the most frequently observed herbivores. Nighttime spearfishing was the dominant fishing method and inner lagoon areas were primarily targeted. A seasonal sales ban (March April), intended to reduce pressure on reproductively active serranids, significantly increased the capture volume of other families. Catch was significantly greater during periods of low lunar illumination, suggesting higher fishing success or greater effort, or both. The marketed catch was dominated by juveniles and small adults, based on fishes of known size at sexual maturity. Artificially depressed market prices appear to be catalyzing (potential or realized) overfishing by increasing the volume of fish needed to offset rising fuel prices. These results support the need for comprehensive fisheries management that produces sustainable fishing and marketing practices and promotes shared management and enforced responsibilities between communities and the state. To be effective, management should prohibit nighttime spearfishing.

Phylogenetic and Chemical Diversity of Three Chemotypes of Bloom-Forming Lyngbya Species (Cyanobacteria: Oscillatoriales) from Reefs of Southeastern Florida▿

PubMed Central

Sharp, Koty; Arthur, Karen E.; Gu, Liangcai; Ross, Cliff; Harrison, Genelle; Gunasekera, Sarath P.; Meickle, Theresa; Matthew, Susan; Luesch, Hendrik; Thacker, Robert W.; Sherman, David H.; Paul, Valerie J.

2009-01-01

The cyanobacterial genus Lyngbya includes free-living, benthic, filamentous cyanobacteria that form periodic nuisance blooms in lagoons, reefs, and estuaries. Lyngbya spp. are prolific producers of biologically active compounds that deter grazers and help blooms persist in the marine environment. Here, our investigations reveal the presence of three distinct Lyngbya species on nearshore reefs in Broward County, FL, sampled in 2006 and 2007. With a combination of morphological measurements, molecular biology techniques, and natural products chemistry, we associated these three Lyngbya species with three distinct Lyngbya chemotypes. One species, identified as Lyngbya cf. confervoides via morphological measurements and 16S rRNA gene sequencing, produces a diverse array of bioactive peptides and depsipeptides. Our results indicate that the other two Lyngbya species produce either microcolins A and B or curacin D and dragonamides C and D. Results from screening for the biosynthetic capacity for curacin production among the three Lyngbya chemotypes in this study correlated that capacity with the presence of curacin D. Our work on these bloom-forming Lyngbya species emphasizes the significant phylogenetic and chemical diversity of the marine cyanobacteria on southern Florida reefs and identifies some of the genetic components of those differences. PMID:19270119

Drowned reefs and antecedent karst topography, Au'au channel, S.E. Hawaiian Islands

USGS Publications Warehouse

Grigg, R.W.; Grossman, E.E.; Earle, S.A.; Gittings, S.R.; Lott, D.; McDonough, J.

2002-01-01

During the last glacial maximum (LGM), about 21,000 years ago, the Hawaiian Islands of Maui, Lanai, and Molokai were interconnected by limestone bridges, creating a super-island known as Maui-Nui. Approximately 120 m of sea-level rise during the Holocene Transgression flooded, and then drowned, these bridges separating the islands by inter-island channels. A new multibeam high-resolution bathymetric survey of the channels between the islands, coupled with observations and video-transects utilizing DeepWorker-2000 submersibles, has revealed the existence of numerous drowned reef features including concentric solution basins, solution ridges (rims), sand and sediment plains, and conical-shaped reef pinnacles. The concentric basins contain flat lagoon-like bottoms that are rimmed by steep-sided limestone walls. Undercut notches rim the basins at several depths, marking either sea-level still stands or paleo-lake levels. All of the solution basins shallower than 120 m were subaerial at the LGM, and at one stage or another may have been shallow shoreline lakes. Today, about 70 drowned reef pinnacles are scattered across the Maui-Lanai underwater bridge and all are situated in wave-sheltered positions. Most drowned during the interval between 14,000 and 10,000 years ago when sea-level rise averaged 15 mm/year. Virtually all of the surficial topography in the Au'au Channel today is a product of karst processes accentuated by marginal reef growth during the Holocene. Both the submerged basins and the drowned reefs represent an archive of sea-level and climate history in Hawaii during the late Quaternary.

Processes Driving Natural Acidification of Western Pacific Coral Reef Waters

NASA Astrophysics Data System (ADS)

Shamberger, K. E.; Cohen, A. L.; Golbuu, Y.; McCorkle, D. C.; Lentz, S. J.; Barkley, H. C.

2013-12-01

Rising levels of atmospheric carbon dioxide (CO2) are acidifying the oceans, reducing seawater pH, aragonite saturation state (Ωar) and the availability of carbonate ions (CO32-) that calcifying organisms use to build coral reefs. Today's most extensive reef ecosystems are located where open ocean CO32- concentration ([CO32-]) and Ωar exceed 200 μmol kg-1 and 3.3, respectively. However, high rates of biogeochemical cycling and long residence times of water can result in carbonate chemistry conditions within coral reef systems that differ greatly from those of nearby open ocean waters. In the Palauan archipelago, water moving across the reef platform is altered by both biological and hydrographic processes that combine to produce seawater pH, Ωar, [CO32-] significantly lower than that of open ocean source water. Just inshore of the barrier reefs, average Ωar values are 0.2 to 0.3 and pH values are 0.02 to 0.03 lower than they are offshore, declining further as water moves across the back reef, lagoon and into the meandering bays and inlets that characterize the Rock Islands. In the Rock Island bays, coral communities inhabit seawater with average Ωar values of 2.7 or less, and as low as 1.9. Levels of Ωar as low as these are not predicted to occur in the western tropical Pacific open ocean until near the end of the century. Calcification by coral reef organisms is the principal biological process responsible for lowering Ωar and pH, accounting for 68 - 99 % of the difference in Ωar between offshore source water and reef water at our sites. However, in the Rock Island bays where Ωar is lowest, CO2 production by net respiration contributes between 17 - 30 % of the difference in Ωar between offshore source water and reef water. Furthermore, the residence time of seawater in the Rock Island bays is much longer than at the well flushed exposed sites, enabling calcification and respiration to drive Ωar to very low levels despite lower net ecosystem calcification rates in the Rock Island bays than on the barrier reef.

Applications of electrical resistivity imaging for characterizing groundwater-surface water interactions from local to regional scales

NASA Astrophysics Data System (ADS)

Cardenas, M. B.; Befus, K. M.; Zamora, P. B.; Ong, J.; Zlotnik, V. A.; Cook, P. L.; Tait, D. R.; Erler, D.; Santos, I. R.; Siringan, F. P.

2012-12-01

Surface water (SW) and groundwater (GW) interact across multiple spatial and temporal scales and their interaction is important for ecological and biogeochemical functions. The mixing of GW and SW has been challenging to simultaneously map with sufficient detail and coverage. Fortunately, ambient differences in salinity of waters occupying geologic formations and sediment are an ideal target for electrical resistivity imaging (ERI). We present examples of the application of ERI for mapping GW discharge and for understanding GW-SW interactions at: (1) a large regulated river, (2) neighboring lakes with differing salinity, (3) fringing coral reefs and lagoons, (4) beaches, and (5) estuaries. In all these cases, the ER tomograms were critical for improving conceptual understanding of GW-SW interactions. At the Lower Colorado River in Austin, Texas (USA), time-lapse ERI was conducted across a 12-hour dam-release cycle when the river stage varied by 0.7 m. Using temporal variability in electrical resistivity (ER) signatures, we identified a shallow well-flushed hyporheic zone, a transition zone where SW and GW mix, and a stable deep zone hosting only GW. In alkaline lakes in the Nebraska Sand Hills (Nebraska, USA), ER surveys using boat-towed cables allowed for mapping the 3D electrical structure underneath the lake. The tomograms were used to distinguish flow-through lakes, which have decreasing subsurface ER from GW inflow to outflow area, from pure GW discharge lakes, which have uniformly stratified increasing-with-depth ER profiles. Moreover, GW plumes in both discharge and recharge zones were clearly outlined underneath the lake. More than 30 km of ER profiles collected via boat-towed surveys over a fringing coral reef in the Philippines identified areas of high ER within the reef that coincide with resistive zones in the seawater. Analysis of 222Rn of bottom waters and vertical conductivity-temperature-depth measurements show the persistence of fresh GW input into the ocean where low salinity and high 222Rn areas coincided with high ER areas. In Muri Lagoon in Rarotonga Island of the Cook Islands, boat-towed ER surveys similarly showed areas underneath the lagoon that have groundwater that is fresher than seawater. Likewise, there was 222Rn high concentrations throughout the lagoon. Closer to shore, ER surveys using fixed electrodes showed complex 3D mixing processes between seawater and terrestrial-sourced fresh groundwater in beach sediment. Lastly, both boat-towed and fixed surveys across the salt wedge of Werribee Estuary west of Melbourne, Australia, outlined the estuarine salt wedge and its relationship with and effect on fresh and nutrient-laden groundwater discharging to the estuary. The examples discussed illustrate that ERI is a powerful and convenient tool for mapping GW discharge and GW-SW interactions across different scales and diverse environments.

Past and present levels of some radionuclides in fish from Bikini and Enewetak Atolls.

PubMed

Noshkin, V E; Robison, W L; Wong, K M; Brunk, J L; Eagle, R J; Jones, H E

1997-07-01

Bikini and Enewetak were the sites in the Northern Marshall Islands that were used by the United States as testing grounds for nuclear devices between 1946 and 1958. The testing produced close-in fallout debris that was contaminated with different radionuclides and which entered the aquatic environment. The contaminated lagoon sediments became a reservoir and source term of manmade radionuclides for the resident marine organisms. This report contains a summary of all the available data on the concentrations of 137Cs, 60Co and 207Bi in flesh samples of reef and pelagic fish collected from Bikini and Enewetak Atolls between 1964 and 1995. The selection of these three radionuclides for discussion is based on the fact that these are the only radionuclides that have been routinely detected by gamma spectrometry in flesh samples from all fish for the last 20 y. Flesh from fish is an important source of food in the Marshallese diet. These radionuclides along with the transuranic radionuclides and 90Sr contribute most of the small radiological dose from ingesting marine foods. Some basic relationships among concentrations in different tissues and organs are discussed. The reef fish can be used as indicator species because their body burden is derived from feeding, over a lifetime, within a relatively small contaminated area of the lagoon. Therefore, the emphasis of this report is to use this extensive and unique concentration data base to describe the effective half lives and cycling for the radionuclides in the marine environments during the 31-y period between 1964 and 1995. The results from an analysis of the radionuclide concentrations in the flesh samples indicate the removal rates for the 3 radionuclides are significantly different. 137Cs is removed from the lagoons with an effective half life of 9-12 y. Little 60Co is mobilized to the water column so that it is depleted in both environments, primarily through radioactive decay. The properties of 207Bi are different at Enewetak and Bikini. At Enewetak the radionuclide is lost from the environment with an effective half live of 5.1 y. At Bikini only radioactive decay can account for the rate at which the radionuclide is lost from the lagoon. The difference in the binding properties of the sedimentary materials for 207Bi among the two Atolls is not understood.

Side-Scan Sonar Imagery of The Recent Seabed and Sediment Properties on The Inner Shelf Off The Lagoons of Küçükçekmece and Büyükçekmece

NASA Astrophysics Data System (ADS)

Alp, H.; Vardar, D.; Alpar, B.

2017-12-01

The sea-bottom sediment distribution, benthic habitats and erosional pathways between Küçükçekmece and Büyükçekmece lagoons at the northern margin of the Marmara Sea were mapped via 340-680 kHz dual frequency side scan sonar, one of the most effective tools for underwater exploration. In fact these lagoons were two former estuaries, later separated from the sea by coarse grained sediments mainly made up of natural sand bars and man-made barriers constructed for roads about a century ago. In the summer 2016, a total of 250-km long side scan data were acquired, with a 300 m of swath width. The coastal strip between the present coastline and the -10 m depth, the seafloor sediments are made up of coarse-grained sandy deposits and determined as continuous bright reflections on the sonograms. Silty and muddy sand units are distributed between the water depths of -10 to -20 m, and they give continuous less bright reflections on sonograms if compared to those of shallow sandy deposits. Deeper muddy units (sandy silt) appeared on the sonograms as uniform dark reflections and soft scatterings. The areal distribution of seafloor sediments and their acoustical characteristics indicated that the net sediment transport in the study area is mainly controlled under the E-W directional longshore currents and dominant southerly waves. Some strong sonar reflections observed at shallow depths (0-15 m) in the Küçükçekmece lagoon and characteristically comprised of remarkable round-shape structures, represent reefs which need sunlight and stable hydrographic conditions to be formed. Various sand ripples are defined in the lagoon, as well.

Last interglacial (MIS5e) sea-levels and uplift along the north-east Gulf of Aqaba

NASA Astrophysics Data System (ADS)

BAR (KOHN), N.; Stein, M.; Agnon, A.; Yehudai, M.; Lazar, B.; Shaked, Y.

2014-12-01

An uplifted flight of coral reef terraces, extending along the north-east margin of the Gulf of Aqaba (GOA), provides evidence for uplift rates and sea level high stands. GOA fills a narrow and deep tectonic depression lying along the southern sector of the Dead Sea Transform where it meets the Red Sea. This special configuration of the GOA and its latitude turn it into a dependable paleo-sea level monitor, sensitive only to global eustatic changes and local tectonic movements. A sequence of five uplifted coral reef terraces were mapped and characterized on basis of morphology and reef-facies, and their elevation above the present sea level was determined. The fossil reefs studied comprise fringing reefs, some with clear reef-structure that includes a reef flat and a shallow back lagoon. Most outcrops in the study area represent a transgressive sequence in which, during its highest stand, formed fringing reef terraces. We use U-Th ages of fossil corals samples found in growth position at various terraces. Corals from three uplifted reef terraces, R1, R2, and R3 were dated to the last interglacial period particularly to marine isotope stage (MIS) 5e. These ages were achieved from mainly calcitic corals (recrystallized in a freshwater phreatic environment). A few ages were derived from aragonite corals. The three terraces represent three sub-stages within MIS5e: R3 formed during a short standstill at ~130 ka BP; R2 formed during a long and steady standstill between ~128 to ~121 ka BP; and R1 represents a short standstill at ~117 ka BP. Assuming that terrace reef flats represent past sea level high stands, we calculated the coast average uplift rate and constrained the original terraces elevations. The reconstructed eustatic sea level variation during MIS 5e at GOA resembles observations from reef terraces in other locations. Combined, all indicate a significant sea-level rise from the MIS 6 low stand at ~134-130 ka and followed by a long and stable sea level high stand between ~128 to ~121 ka, representing a major reef building period. The long and stable sea level was followed by additional sea-level rise at ~118-116 ka that transgressed over the "stable reefs".

Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages

PubMed Central

Waheed, Zarinah; van Mil, Harald G. J.; Syed Hussein, Muhammad Ali; Jumin, Robecca; Golam Ahad, Bobita; Hoeksema, Bert W.

2015-01-01

The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP) by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractinian species richness, and benthic reef assemblages following the Reef Check substrate categories, with emphasis on hard coral cover. Variation in scleractinian diversity was based on the species composition of coral families Fungiidae (n = 39), Agariciidae (n = 30) and Euphylliidae (n = 15). The number of coral species was highest at reefs with a larger depth gradient i.e. at the periphery of the study area and in the deep South Banggi Channel. Average live hard coral cover across the sites was 49%. Only 7% of the examined reefs had > 75% hard coral cover, while the majority of the reef sites were rated fair (51%) and good (38%). Sites with low coral cover and high rubble fragments are evidence of blast fishing, although the observed damage appeared old. Depth was a dominant factor in influencing the coral species composition and benthic reef communities in the TMP. Besides filling in the information gaps regarding species richness and benthic cover for reef areas that were previously without any data, the results of this study together with information that is already available on the coral reefs of TMP will be used to make informed decisions on zoning plans for conservation priorities in the proposed park. PMID:26719987

Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages.

PubMed

Waheed, Zarinah; van Mil, Harald G J; Syed Hussein, Muhammad Ali; Jumin, Robecca; Golam Ahad, Bobita; Hoeksema, Bert W

2015-01-01

The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP) by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractinian species richness, and benthic reef assemblages following the Reef Check substrate categories, with emphasis on hard coral cover. Variation in scleractinian diversity was based on the species composition of coral families Fungiidae (n = 39), Agariciidae (n = 30) and Euphylliidae (n = 15). The number of coral species was highest at reefs with a larger depth gradient i.e. at the periphery of the study area and in the deep South Banggi Channel. Average live hard coral cover across the sites was 49%. Only 7% of the examined reefs had > 75% hard coral cover, while the majority of the reef sites were rated fair (51%) and good (38%). Sites with low coral cover and high rubble fragments are evidence of blast fishing, although the observed damage appeared old. Depth was a dominant factor in influencing the coral species composition and benthic reef communities in the TMP. Besides filling in the information gaps regarding species richness and benthic cover for reef areas that were previously without any data, the results of this study together with information that is already available on the coral reefs of TMP will be used to make informed decisions on zoning plans for conservation priorities in the proposed park.

An assessment of chemical contaminants in sediments from the St. Thomas East End Reserves, St. Thomas, USVI.

PubMed

Pait, Anthony S; Hartwell, S Ian; Mason, Andrew L; Warner, Robert A; Jeffrey, Christopher F G; Hoffman, Anne M; Apeti, Dennis A; Pittman, Simon J

2014-08-01

The St. Thomas East End Reserves or STEER is located on the southeastern end of the island of St. Thomas, USVI. The STEER contains extensive mangroves and seagrass beds, along with coral reefs, lagoons, and cays. Within the watershed, however, are a large active landfill, numerous marinas, resorts, various commercial activities, an EPA Superfund Site, and residential areas, all of which have the potential to contribute pollutants to the STEER. As part of a project to develop an integrated assessment for the STEER, 185 chemical contaminants were analyzed in sediments from 24 sites. Higher levels of chemical contaminants were found in Mangrove Lagoon and Benner Bay in the western portion of the study area. The concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT), zinc, copper, lead, and mercury were above a NOAA Effects Range-Low (ERL) sediment quality guideline at one or more sites, indicating impacts may be present in more sensitive species or life stages. Copper at one site in Benner Bay was above a NOAA Effects Range-Median (ERM) guideline indicating effects on benthic organisms were likely. The antifoulant boat hull ingredient tributyltin (TBT) was found at the third highest concentration in the history of NOAA's National Status and Trends (NS&T) Program, which monitors the nation's coastal and estuarine waters for chemical contaminants and bioeffects. The results from this project will provide resource managers with key information needed to make effective decisions affecting coral reef ecosystem health and gauge the efficacy of restoration activities.

Long-Term Effects of the Cleaner Fish Labroides dimidiatus on Coral Reef Fish Communities

PubMed Central

Waldie, Peter A.; Blomberg, Simon P.; Cheney, Karen L.; Goldizen, Anne W.; Grutter, Alexandra S.

2011-01-01

Cleaning behaviour is deemed a mutualism, however the benefit of cleaning interactions to client individuals is unknown. Furthermore, mechanisms that may shift fish community structure in the presence of cleaning organisms are unclear. Here we show that on patch reefs (61–285 m2) which had all cleaner wrasse Labroides dimidiatus (Labridae) experimentally removed (1–5 adults reef−1) and which were then maintained cleaner-fish free over 8.5 years, individuals of two site-attached (resident) client damselfishes (Pomacentridae) were smaller compared to those on control reefs. Furthermore, resident fishes were 37% less abundant and 23% less species rich per reef, compared to control reefs. Such changes in site-attached fish may reflect lower fish growth rates and/or survivorship. Additionally, juveniles of visitors (fish likely to move between reefs) were 65% less abundant on removal reefs suggesting cleaners may also affect recruitment. This may, in part, explain the 23% lower abundance and 33% lower species richness of visitor fishes, and 66% lower abundance of visitor herbivores (Acanthuridae) on removal reefs that we also observed. This is the first study to demonstrate a benefit of cleaning behaviour to client individuals, in the form of increased size, and to elucidate potential mechanisms leading to community-wide effects on the fish population. Many of the fish groups affected may also indirectly affect other reef organisms, thus further impacting the reef community. The large-scale effect of the presence of the relatively small and uncommon fish, Labroides dimidiadus, on other fishes is unparalleled on coral reefs. PMID:21731670

Habitat Specialization in Tropical Continental Shelf Demersal Fish Assemblages

PubMed Central

Fitzpatrick, Ben M.; Harvey, Euan S.; Heyward, Andrew J.; Twiggs, Emily J.; Colquhoun, Jamie

2012-01-01

The implications of shallow water impacts such as fishing and climate change on fish assemblages are generally considered in isolation from the distribution and abundance of these fish assemblages in adjacent deeper waters. We investigate the abundance and length of demersal fish assemblages across a section of tropical continental shelf at Ningaloo Reef, Western Australia, to identify fish and fish habitat relationships across steep gradients in depth and in different benthic habitat types. The assemblage composition of demersal fish were assessed from baited remote underwater stereo-video samples (n = 304) collected from 16 depth and habitat combinations. Samples were collected across a depth range poorly represented in the literature from the fringing reef lagoon (1–10 m depth), down the fore reef slope to the reef base (10–30 m depth) then across the adjacent continental shelf (30–110 m depth). Multivariate analyses showed that there were distinctive fish assemblages and different sized fish were associated with each habitat/depth category. Species richness, MaxN and diversity declined with depth, while average length and trophic level increased. The assemblage structure, diversity, size and trophic structure of demersal fishes changes from shallow inshore habitats to deeper water habitats. More habitat specialists (unique species per habitat/depth category) were associated with the reef slope and reef base than other habitats, but offshore sponge-dominated habitats and inshore coral-dominated reef also supported unique species. This suggests that marine protected areas in shallow coral-dominated reef habitats may not adequately protect those species whose depth distribution extends beyond shallow habitats, or other significant elements of demersal fish biodiversity. The ontogenetic habitat partitioning which is characteristic of many species, suggests that to maintain entire species life histories it is necessary to protect corridors of connected habitats through which fish can migrate. PMID:22761852

The Micronesia Challenge: Assessing the Relative Contribution of Stressors on Coral Reefs to Facilitate Science-to-Management Feedback

PubMed Central

Houk, Peter; Camacho, Rodney; Johnson, Steven; McLean, Matthew; Maxin, Selino; Anson, Jorg; Joseph, Eugene; Nedlic, Osamu; Luckymis, Marston; Adams, Katrina; Hess, Don; Kabua, Emma; Yalon, Anthony; Buthung, Eva; Graham, Curtis; Leberer, Trina; Taylor, Brett; van Woesik, Robert

2015-01-01

Fishing and pollution are chronic stressors that can prolong recovery of coral reefs and contribute to ecosystem decline. While this premise is generally accepted, management interventions are complicated because the contributions from individual stressors are difficult to distinguish. The present study examined the extent to which fishing pressure and pollution predicted progress towards the Micronesia Challenge, an international conservation strategy initiated by the political leaders of 6 nations to conserve at least 30% of marine resources by 2020. The analyses were rooted in a defined measure of coral-reef-ecosystem condition, comprised of biological metrics that described functional processes on coral reefs. We report that only 42% of the major reef habitats exceeded the ecosystem-condition threshold established by the Micronesia Challenge. Fishing pressure acting alone on outer reefs, or in combination with pollution in some lagoons, best predicted both the decline and variance in ecosystem condition. High variances among ecosystem-condition scores reflected the large gaps between the best and worst reefs, and suggested that the current scores were unlikely to remain stable through time because of low redundancy. Accounting for the presence of marine protected area (MPA) networks in statistical models did little to improve the models’ predictive capabilities, suggesting limited efficacy of MPAs when grouped together across the region. Yet, localized benefits of MPAs existed and are expected to increase over time. Sensitivity analyses suggested that (i) grazing by large herbivores, (ii) high functional diversity of herbivores, and (iii) high predator biomass were most sensitive to fishing pressure, and were required for high ecosystem-condition scores. Linking comprehensive fisheries management policies with these sensitive metrics, and targeting the management of pollution, will strengthen the Micronesia Challenge and preserve ecosystem services that coral reefs provide to societies in the face of climate change. PMID:26087252

The Micronesia Challenge: Assessing the Relative Contribution of Stressors on Coral Reefs to Facilitate Science-to-Management Feedback.

PubMed

Houk, Peter; Camacho, Rodney; Johnson, Steven; McLean, Matthew; Maxin, Selino; Anson, Jorg; Joseph, Eugene; Nedlic, Osamu; Luckymis, Marston; Adams, Katrina; Hess, Don; Kabua, Emma; Yalon, Anthony; Buthung, Eva; Graham, Curtis; Leberer, Trina; Taylor, Brett; van Woesik, Robert

2015-01-01

Fishing and pollution are chronic stressors that can prolong recovery of coral reefs and contribute to ecosystem decline. While this premise is generally accepted, management interventions are complicated because the contributions from individual stressors are difficult to distinguish. The present study examined the extent to which fishing pressure and pollution predicted progress towards the Micronesia Challenge, an international conservation strategy initiated by the political leaders of 6 nations to conserve at least 30% of marine resources by 2020. The analyses were rooted in a defined measure of coral-reef-ecosystem condition, comprised of biological metrics that described functional processes on coral reefs. We report that only 42% of the major reef habitats exceeded the ecosystem-condition threshold established by the Micronesia Challenge. Fishing pressure acting alone on outer reefs, or in combination with pollution in some lagoons, best predicted both the decline and variance in ecosystem condition. High variances among ecosystem-condition scores reflected the large gaps between the best and worst reefs, and suggested that the current scores were unlikely to remain stable through time because of low redundancy. Accounting for the presence of marine protected area (MPA) networks in statistical models did little to improve the models' predictive capabilities, suggesting limited efficacy of MPAs when grouped together across the region. Yet, localized benefits of MPAs existed and are expected to increase over time. Sensitivity analyses suggested that (i) grazing by large herbivores, (ii) high functional diversity of herbivores, and (iii) high predator biomass were most sensitive to fishing pressure, and were required for high ecosystem-condition scores. Linking comprehensive fisheries management policies with these sensitive metrics, and targeting the management of pollution, will strengthen the Micronesia Challenge and preserve ecosystem services that coral reefs provide to societies in the face of climate change.

Quantitative Analyse der Korallenbesiedlung eines Vorriffareals bei Aqaba (Rotes Meer)

NASA Astrophysics Data System (ADS)

Mergner, H.; Schuhmacher, H.

1981-09-01

Previous descriptions of the ecology and zonation of Aqaba reefs (Mergner & Schuhmacher, 1974) are supplemented by this quantitative study of a test quadrat (5×5 m in size), randomly chosen in some 10 m depth in the middle fore reef of a coastal fringing reef. Of the total surface of 25 m2 Cnidaria represent 42.31%, sponges 0.17%, calcareous algae 0.20%, dead coral rock and pebble 30.27% and sand and coral debris 26.15%. The cnidarian cover is roughly equally contributed by 50.86% Scleractinia and 48.61% Alcyonaria, mainly Xeniidae (35.81%). For each species the percentage of the total cover (measured as vertical projection), colony number, average and maximal colony size are given. A total number of 104 cnidarian species was recorded, among which the 78 scleractinian species represent 34 of the 55 coral genera known from the Red Sea. The well balanced regime of moderate light and current conditions which are tolerated both by shallow and deep water species may account for the high species number. Disturbances such as occasional sedimentation, grazing of sea urchins (Diadema setosum) and overgrowth of stony corals by xeniids result in continuous fluctuations of the coral community, in small colony size and in high colony number. Abiotic factors and biotic interactions maintain a diversity (H=3.67) which ranks among the greatest ever found in reef communities. The data obtained from the fore reef square are compared with those of a similar test square in the lagoon of the same reef and with results from transect zonations on the opposite coast of the Gulf of Aqaba. These comparisons indicate that the fore reef harbours the richest coral fauna in the reef. The inventory of coral species at the northern end of the Gulf of Aqaba, one of the northernmost outposts of the coral reef belt, is only little reduced when compared with that of the central Red Sea; this great species diversity is in contrast to the worldwide decrease of species number towards the periphery of the reef belt.

Ecotoxicological effects of a semi-submerged municipal dump (Castle harbour, Bermuda) on the Calico scallop Argopecten gibbus.

PubMed

Quinn, Brian; Gagné, Francois; Weber, Jean-Philippe; Blaise, Christian

2005-01-01

A biomarker study was undertaken using the Calico scallop Argopecten gibbus to assess the ecotoxicological effects of a semi-submerged municipal dump on the adjacent patch reef lagoon ecosystem (Castle harbour, Bermuda). Caged scallops were deployed in situ for 2 months at various distances from the dump (50 m, 900 m and 2.7 km) and at a reference site (14 km). A suite of biomarkers comprising metallothionein (MT), lipid peroxidation (LPO), vitellin-like proteins (Vn), glutathione S-transferase (GST), DNA strand breaks and condition factor (CF) were investigated in various tissues of the scallop (gill, digestive gland and gonad). Levels of heavy metals were also measured in the whole scallop soft tissue. While there was some variation in response between tissues, in general the results indicated that the dump was negatively impacting scallops deployed in the adjacent marine environment: elevated levels of MT, DNA strand breaks, Vn and GST and reduced condition factor were found for scallops deployed nearest to the dump and at the site 1.5 km from this point source of contamination (Tuckers town) in Castle harbour, with respect to the reference site, North Rock (although this exhibited some degree of metal contamination). The gills from scallops deployed at the dump site were the most responsive tissue, with the highest expression of MT, LPO and DNA damage. This study indicates the potential of the Calico scallop as a convenient bioindicator species in the marine tropical benthos.

KSC-03pd1379

NASA Image and Video Library

2003-05-02

KENNEDY SPACE CENTER, FLA. - Andrew Shepard, expedition leader, National Undersea Research Center, University of North Carolina at Wilmington, N. Car., poses on deck of the Liberty Star with some of the equipment to be used in the Oculina Banks project. The ship will be the site of an undersea expedition to characterize the condition of the deep-sea coral reefs and reef fish populations in the Oculina Banks, a marine protected area, 20 miles offshore of the east coast of Florida. He and other scientists will be deploying an underwater robot, a seafloor sampler, and the Passive Acoustic Monitoring System (PAMS). Dr. Grant Gilmore was co-principle investigator of the PAMS, originally developed by NASA to monitor the impact of rocket launches on wildlife refuge lagoons at KSC. The research is sponsored by NOAA Fisheries. The ship departed from Port Canaveral April 29 and will return May 9.

Fine-scale environmental specialization of reef-building corals might be limiting reef recovery in the Florida Keys.

PubMed

Kenkel, Carly D; Almanza, Albert T; Matz, Mikhail V

2015-12-01

Despite decades of monitoring global reef decline, we are still largely unable to explain patterns of reef deterioration at local scales, which precludes the development of effective management strategies. Offshore reefs of the Florida Keys, USA, experience milder temperatures and lower nutrient loads in comparison to inshore reefs yet remain considerably more degraded than nearshore patch reefs. A year-long reciprocal transplant experiment of the mustard hill coral (Porites astreoides) involving four source and eight transplant locations reveals that corals adapt and/or acclimatize to their local habitat on a < 10-km scale. Surprisingly, transplantation to putatively similar environmental types (e.g., offshore corals moved to a novel offshore site, or along-shore transplantation) resulted in greater reductions in fitness proxies, such as coral growth, than cross-channel transplantation between inshore and offshore reefs. The only abiotic factor showing significantly greater differences between along-shore sites was daily temperature range extremes (rather than the absolute high or low temperatures reached), providing a possible explanation for this pattern. Offshore-origin corals exhibited significant growth reductions at sites with greater daily temperature ranges, which explained up to 39% of the variation in their mass gain. In contrast, daily temperature range explained at most 9% of growth variation in inshore-origin corals, suggesting that inshore corals are more tolerant of high-frequency temperature fluctuations. Finally, corals incur trade-offs when specializing to their native reef. Across reef locations the coefficient of selection against coral transplants was 0.07 ± 0.02 (mean ± SE). This selection against immigrants could hinder the ability of corals to recolonize devastated reefs, whether through assisted migration efforts or natural recruitment events, providing a unifying explanation for observed patterns of coral decline in this reef system.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rosen, M.R.; Collins, L.B.; Wyrwoll, K.H.

The Houtman Abrolhos reefs are located 80 km off the west coast of Australia between latitudes 28 and 29{degree} south. The islands are situated on three Pleistocene carbonate reef platforms which rise above the surrounding shelf. The modern coral reefs are close to the geographic limit for coral growth in the southern hemisphere and survive due to the presence of the Leeuwin current (a poleward-flowing warm stream). Two major shallow-water benthic communities coexist in the Abrolhos: a macroalgal-dominated community on the windward platform margins and a coral-dominated community on the leeward margins. These communities overlap-particularly in the platform lagoons, wheremore » competition between macroalgae and corals is intense. This interaction has been suggested as a major factor controlling the growth of cord reefs at high latitudes. The Holocene carbonate sediments lack nonskeletal components and are dominated by coral and coralline algal fragments with subordinate molluskan and echinoderm debris. The accumulations can be grouped into the following major facies: (1) coral framestone and coralline algal/serpulid boundstone, (2) submarine sand sheets, (3) subaerial coral storm ridges, (4-) peritidal to subtidal shingle and rubble veneers composed of dominantly coral debris, and (5) eolian dunes and beach sand. The Holocene sediment is a thin (< 2 m) veneer on the Pleistocene reef platform, which is emergent as small islands. The Pleistocene platform is composed of reef facies that can be directly related to the Holocene sediments. The platform is composed of framestone and boundstone facies (corals and coralline algal/serpulid facies), rudstones (submarine coral rubble facies), planar-bedded skeletal grainstones dipping 12-13{degree} (submarine sand sheet and peritidal shingle facies), and large 15-m-high eolianite dunes (eolian dune facies).« less

Spatial patterns of self-recruitment of a coral reef fish in relation to island-scale retention mechanisms.

PubMed

Beldade, Ricardo; Holbrook, Sally J; Schmitt, Russell J; Planes, Serge; Bernardi, Giacomo

2016-10-01

Oceanographic features influence the transport and delivery of marine larvae, and physical retention mechanisms, such as eddies, can enhance self-recruitment (i.e. the return of larvae to their natal population). Knowledge of exact locations of hatching (origin) and settlement (arrival) of larvae of reef animals provides a means to compare observed patterns of self-recruitment 'connectivity' with those expected from water circulation patterns. Using parentage inference based on multiple sampling years in Moorea, French Polynesia, we describe spatial and temporal variation in self-recruitment of the anemonefish Amphiprion chrysopterus, evaluate the consistency of net dispersal distances of self-recruits against the null expectation of passive particle dispersal and test the hypothesis that larvae originating in certain reef habitats (lagoons and passes) would be retained and thus more likely to self-recruit than those originating on the outer (fore) reef. Estimates of known self-recruitment were consistent across the sampling years (~25-27% of sampled recruits). For most (88%) of these self-recruits, the net distance between hatching and settlement locations was within the maximum dispersal distance expected for a neutrally buoyant passive particle based on the longest duration of the larval dispersive phase and the average direction and speed of current flow around Moorea. Furthermore, a parent of a given body size on the outer (fore) reef of Moorea was less likely to produce self-recruits than those in passes. Our findings show that even a simple dispersal model based on net average flow and direction of alongshore currents can provide insight into landscape-scale retention patterns of reef fishes. © 2016 John Wiley & Sons Ltd.

An exceptionally preserved Eocene shark and the rise of modern predator-prey interactions in the coral reef food web.

PubMed

Fanti, Federico; Minelli, Daniela; Conte, Gabriele Larocca; Miyashita, Tetsuto

2016-01-01

Following extreme climatic warming events, Eocene Lagerstätten document aquatic and terrestrial vertebrate faunas surprisingly similar to modern counterparts. This transition in marine systems is best documented in the earliest teleost-dominated coral reef assemblage of Pesciara di Bolca, northern Italy, from near the end of the Eocene Climatic Optimum. Its rich fauna shows similarities with that of the modern Great Barrier Reef in niche exploitation by and morphological disparity among teleost primary consumers. However, such paleoecological understanding has not transcended trophic levels above primary consumers, particularly in carcharhiniform sharks. We report an exceptionally preserved fossil school shark (Galeorhinus cuvieri) from Pesciara di Bolca. In addition to the spectacular preservation of soft tissues, including brain, muscles, and claspers, this male juvenile shark has stomach contents clearly identifiable as a sphyraenid acanthomorph (barracuda). This association provides evidence that a predator-prey relationship between Galeorhinus and Sphyraena in the modern coral reefs has roots in the Eocene. A growth curve of the living species of Galeorhinus fitted to G. cuvieri suggests that all specimens of G. cuvieri from the lagoonal deposits of Bolca represent sexually and somatically immature juveniles. The modern trophic association between higher-degree consumers (Galeorhinus and Sphyraena) has a counterpart in the Eocene Bolca, just as Bolca and the Great Barrier Reef show parallels among teleost primary consumers. Given the age of Bolca, trophic networks among consumers observed in modern coral reefs arose by the exit from the Climatic Optimum. The biased representation of juveniles suggests that the Bolca Lagerstätte served as a nursery habitat for G. cuvieri. Ultraviolet photography may be useful in probing for exceptional soft tissue preservation before common acid preparation methods.

Variability in the CO2-carbonic Acid System Parameters Across Coral Reef Settings in Hawaii: Perspectives from Multi-year Records from NOAA/PMEL MAPCO2 Buoys

NASA Astrophysics Data System (ADS)

De Carlo, E. H.; Drupp, P. S.; Thompson, R. W.; Mackenzie, F. T.; Muscielewicz, S.; Jones, S. M.; Feely, R. A.; Sabine, C. L.

2012-12-01

A series of MAP-CO2 buoys deployed in the coastal waters of Hawaii have produced multiyear high temporal resolution CO2 records in four different coral reef environments of the island of Oahu, Hawaii. This study is part of an integrated effort to understand the factors that influence the dynamics of CO2-carbonic acid system parameters in waters bathing Pacific high island coral reef ecosystems and subject to differing natural and anthropogenic stresses. The MAP-CO2 buoys are located in backreef, lagoonal, and fringing reef sites, and measure CO2 and O2 in seawater and in the atmosphere. Other sensors on the buoys record physical and biogeochemical parameters (CTD, chl-a, turbidity, pH, nitrate). The buoy records, when combined with data from synoptic spatial sampling, have allowed us to examine the interplay between biological cycles of productivity/respiration and calcification/dissolution and biogeochemical and physical forcing on hourly to inter-annual time scales, including those of land runoff. Our data demonstrate that coral reefs are subject to a wide range of pCO2, both on short and long time scales, and significant differences in the CO2-carbonic acid system dynamics across these various settings. We report that coral communities currently thrive in areas where the concentrations of CO2 can range from extremes as low as 200 ppm to as high as 1000 ppm and can fluctuate by ~500 ppm on any given day. The data provide evidence that net ecosystem calcification currently occurs in the presence of levels of CO2 predicted to occur well into the next century, although these coral reef ecosystems are only exposed to the extremes for short periods of time each day.

Biology and ecology of the vulnerable holothuroid, Stichopus herrmanni, on a high-latitude coral reef on the Great Barrier Reef

NASA Astrophysics Data System (ADS)

Wolfe, Kennedy; Byrne, Maria

2017-12-01

Tropical aspidochirotid holothuroids are among the largest coral reef invertebrates, but gaps remain in our understanding of their ecological roles in lagoon sediment habitats, a vast component of coral-reef ecosystems. Stichopus herrmanni, listed as vulnerable (IUCN), is currently a major fishery species on the Great Barrier Reef (GBR) and throughout the Indo-Pacific. It is critical to characterise how this species interacts with its environment to understand how its removal may impact ecosystem functionality. We investigated seasonal variation in movement, bioturbation, feeding and gonad development of S. herrmanni over 3 yr at One Tree Reef, which has been a no-take area for decades. We determined the direct influence of the deposit-feeding activity of S. herrmanni on sediment turnover and granulometry, and on the abundance of infauna and benthic productivity in a comprehensive in situ analysis of tropical holothuroid feeding ecology. This species is highly mobile with identifiable individuals exhibiting site fidelity over 3 yr. With the potential to turn over an estimated 64-250 kg individual-1 yr-1, S. herrmanni is a major bioturbator. Stichopus herrmanni is a generalist feeder and influences trophic interactions by altering the abundance of infauna and microalgae. Stichopus herrmanni exhibited decreased feeding activity and gonad development in winter, the first documentation of a seasonal disparity in the bioturbation activity of a tropical holothuroid. Sediment digestion and dissolution by S. herrmanni has the potential to influence seawater chemistry, a particularly important feature in a changing ocean. Our results provide essential baseline data on the functional roles of this ecologically important species to inform development of ecosystem-based bêche-de-mer fisheries management on the GBR.

Symbiont community stability through severe coral bleaching in a thermally extreme lagoon.

PubMed

Smith, E G; Vaughan, G O; Ketchum, R N; McParland, D; Burt, J A

2017-05-25

Coral reefs are threatened by climate change as coral-algal symbioses are currently living close to their upper thermal limits. The resilience of the algal partner plays a key role in determining the thermal tolerance of the coral holobiont and therefore, understanding the acclimatory limits of present day coral-algal symbioses is fundamental to forecasting corals' responses to climate change. This study characterised the symbiont community in a highly variable and thermally extreme (Max = 37.5 °C, Min = 16.8 °C) lagoon located in the southern Persian/Arabian Gulf using next generation sequencing of ITS2 amplicons. Despite experiencing extreme temperatures, severe bleaching and many factors that would be expected to promote the presence of, or transition to clade D dominance, the symbiont communities of the lagoon remain dominated by the C3 variant, Symbiodinium thermophilum. The stability of this symbiosis across multiple genera with different means of symbiont transmission highlights the importance of Symbiodinium thermophilum for corals living at the acclimatory limits of modern day corals. Corals in this extreme environment did not undergo adaptive bleaching, suggesting they are living at the edge of their acclimatory potential and that this valuable source of thermally tolerant genotypes may be lost in the near future under climate change.

Understanding the Role of Typhoons, Fire, and Climate on the Vegetation Dynamics of Tropical Dry Forests: Looking to the Past to Develop Future Management Solutions

DTIC Science & Technology

2010-04-01

centennial -to millennial scale typhoon reconstructions from the western North Pacific are far more limited. Historical government documents of typhoon... Centennial scale swings from humid to drought conditions have been documented in some tropical locations (Hodell et al., 2001). By looking to the past... depressions with a maximum depth of roughly 12 meters. The lagoon hollows are bounded by sand flats and coral reefs (Fig. 2). Core VC9 was located in the

Nutrient inputs from the watershed and coastal eutrophication in the Florida Keys

DOE Office of Scientific and Technical Information (OSTI.GOV)

LaPointe, B.E.; Clark, M.W.

1992-12-01

Widespread use of septic tanks in the Florida Keys increase the nutrient concentrations of limestone ground waters that discharge into shallow nearshore waters, resulting in coastal eutrophication. This study characterizes watershed nutrient inputs, transformations, and effects along a land-sea gradient stratified into four ecosystems that occur with increasing distance from land: manmade canal systems, seagrass meadows, patch reefs, and offshore bank reefs. Soluble reactive phosphorus (SRP), the primary limiting nutrient, was significantly elevated in canal systems, while dissolved inorganic nitrogen (DIN; NH[sub 4][sup =] and NO[sub 3][sup [minus

Cambrian Series 3 carbonate platform of Korea dominated by microbial-sponge reefs

NASA Astrophysics Data System (ADS)

Hong, Jongsun; Lee, Jeong-Hyun; Choh, Suk-Joo; Lee, Dong-Jin

2016-07-01

Metazoans have been considered as negligible components of Cambrian Series 3 and Furongian microbial-dominated reefs, in contrast to their presence in earlier Terreneuvian-Cambrian Series 2 microbial-archaeocyath reefs. However, recent discoveries of sponges in Cambrian Series 3-Furongian reefs of Australia, China, Iran, USA, and Korea have raised question regarding their contribution in terms of carbonate platform development, which have never been assessed. This study examines Cambrian Series 3 deposits of the Daegi Formation, Korea to elucidate this question. The 100-m-thick middle part of the Daegi Formation is dominated by boundstone facies, which occupies 45% of the study interval, as well as bioclastic wackestone to packstone, bioclastic grainstone, and ooid packstone to grainstone facies. The Daegi reefs are primarily thrombolitic in composition, with 90% (n = 26/29) of the reefs containing an average of 9% sponges in aerial percentage calculated from thin sections. Lithistid sponges composed of peloidal fabrics, some desma spicules, and spicule networks commonly occupy the interstitial space in microbial clusters, are encrusted by mesoclots and Epiphyton, and are surrounded by micrite. Subordinate non-lithistid demosponges occur within clusters of microbial elements. The middle Daegi Formation can be largely subdivided into shoal environment dominated by grainstone to packstone facies and shallow subtidal platform interior environment located behind shoal with wackestone to packstone facies. The microbial-sponge reefs mainly developed around platform interior as patch reefs. The current study indicates that metazoans in the form of lithistid and non-lithistid demosponges are nearly ubiquitously incorporated in Daegi reefs and contributed greatly to the formation of microbial-sponge reefs as well as carbonate platform during the time. Study of these microbial-sponge reefs and their distribution within the carbonate platform may help us to understand how carbonate sedimentary environments responded to the extinction of archaeocyaths.

Mg/Ca and Sr/Ca as novel geochemical proxies for understanding sediment transport processes within coral reefs

NASA Astrophysics Data System (ADS)

Gacutan, J.; Vila-Concejo, A.; Nothdurft, L. D.; Fellowes, T. E.; Cathey, H. E.; Opdyke, B. N.; Harris, D. L.; Hamylton, S.; Carvalho, R. C.; Byrne, M.; Webster, J. M.

2017-10-01

Sediment transport is a key driver of reef zonation and biodiversity, where an understanding of sediment dynamics gives insights into past reef processes and allows the prediction of geomorphic responses to changing environmental conditions. However, modal conditions within the back-reef seldom promote sediment transport, hence direct observation is inherently difficult. Large benthic foraminifera (LBF) have previously been employed as 'tracers' to infer sediment transport pathways on coral reefs, as their habitat is largely restricted to the algal flat and post-mortem, their calcium carbonate test is susceptible to sediment transport forces into the back-reef. Foraminiferal test abundance and post-depositional test alteration have been used as proxies for sediment transport, although the resolution of these measures becomes limited by low test abundance and the lack of variation within test alteration. Here we propose the novel use of elemental ratios as a proxy for sediment transport. Two species, Baculogypsina sphaerulata and Calcarina capricornia, were analysed using a taphonomic index within One Tree and Lady Musgrave reefs, Great Barrier Reef (Australia). Inductively coupled plasma-atomic emission spectrometry (ICP-AES) was used to determine Mg/Ca and Sr/Ca and these ratios were compared with taphonomic data. Decreases in test Mg/Ca accompany increases in Sr/Ca in specimens from algal-flat to lagoonal samples in both species, mirroring trends indicated by taphonomic values, therefore indicating a relationship with test alteration. To delineate mechanisms driving changes in elemental ratios, back-scattered electron (BSE) images, elemental mapping and in situ quantitative spot analyses by electron microprobe microanalysis (EPMA) using wavelength dispersive X-ray spectrometers (WDS) were performed on un-altered algal flat and heavily abraded tests for both species. EPMA analyses reveal heterogeneity in Mg/Ca between spines and the test wall, implying the loss of appendages results in a decrease in Mg/Ca. BSE imaging and WDS elemental mapping provided evidence for cementation, facilitated by microbial-boring as the primary cause of increasing Sr/Ca. These novel proxies hold advantages over taphonomic measures and further provide a rapid method to infer sediment transport pathways within back-reef environments.

Spatial Patterns in the Distribution, Diversity and Abundance of Benthic Foraminifera around Moorea (Society Archipelago, French Polynesia)

PubMed Central

2015-01-01

Coral reefs are now subject to global threats and influences from numerous anthropogenic sources. Foraminifera, a group of unicellular shelled organisms, are excellent indicators of water quality and reef health. Thus we studied a set of samples taken in 1992 to provide a foraminiferal baseline for future studies of environmental change. Our study provides the first island-wide analysis of shallow benthic foraminifera from around Moorea (Society Archipelago). We analyzed the composition, species richness, patterns of distribution and abundance of unstained foraminiferal assemblages from bays, fringing reefs, nearshore and back- and fore-reef environments. A total of 380 taxa of foraminifera were recorded, a number that almost doubles previous species counts. Spatial patterns of foraminiferal assemblages are characterized by numerical abundances of individual taxa, cluster groups and gradients of species richness, as documented by cluster, Fisher α, ternary plot and Principal Component Analyses (PCA). The inner bay inlets are dominated by stress-tolerant, mostly thin-shelled taxa of Bolivina, Bolivinella, Nonionoides, Elongobula, and Ammonia preferring low-oxygen and/or nutrient-rich habitats influenced by coastal factors such as fresh-water runoff and overhanging mangroves. The larger symbiont-bearing foraminifera (Borelis, Amphistegina, Heterostegina, Peneroplis) generally live in the oligotrophic, well-lit back- and fore-reef environments. Amphisteginids and peneroplids were among the few taxa found in the bay environments, probably due to their preferences for phytal substrates and tolerance to moderate levels of eutrophication. The fringing reef environments along the outer bay are characterized by Borelis schlumbergeri, Heterostegina depressa, Textularia spp. and various miliolids which represent a hotspot of diversity within the complex reef-lagoon system of Moorea. The high foraminiferal Fisher α and species richness diversity in outer bay fringing reefs is consistent with the disturbance-mosaic (microhabitat heterogeneity) hypothesis. Calculations of the FORAM Index (FI), a single metric index to assess reef vitality, indicate that all fore- and most back-reef environments support active carbonate accretion and provide habitat suitability for carbonate producers dependent on algal symbiosis. Lowest suitability values were recorded within the innermost bays, an area where natural and increasing anthropogenic influences continue to impact the reefs. The presence of habitat specific assemblages and numerical abundance values of individual taxa show that benthic foraminifera are excellent recorders of environmental perturbations and good indicators useful in modern and ancient ecological and environmental studies. PMID:26710320

Spatial Patterns in the Distribution, Diversity and Abundance of Benthic Foraminifera around Moorea (Society Archipelago, French Polynesia).

PubMed

Fajemila, Olugbenga T; Langer, Martin R; Lipps, Jere H

2015-01-01

Coral reefs are now subject to global threats and influences from numerous anthropogenic sources. Foraminifera, a group of unicellular shelled organisms, are excellent indicators of water quality and reef health. Thus we studied a set of samples taken in 1992 to provide a foraminiferal baseline for future studies of environmental change. Our study provides the first island-wide analysis of shallow benthic foraminifera from around Moorea (Society Archipelago). We analyzed the composition, species richness, patterns of distribution and abundance of unstained foraminiferal assemblages from bays, fringing reefs, nearshore and back- and fore-reef environments. A total of 380 taxa of foraminifera were recorded, a number that almost doubles previous species counts. Spatial patterns of foraminiferal assemblages are characterized by numerical abundances of individual taxa, cluster groups and gradients of species richness, as documented by cluster, Fisher α, ternary plot and Principal Component Analyses (PCA). The inner bay inlets are dominated by stress-tolerant, mostly thin-shelled taxa of Bolivina, Bolivinella, Nonionoides, Elongobula, and Ammonia preferring low-oxygen and/or nutrient-rich habitats influenced by coastal factors such as fresh-water runoff and overhanging mangroves. The larger symbiont-bearing foraminifera (Borelis, Amphistegina, Heterostegina, Peneroplis) generally live in the oligotrophic, well-lit back- and fore-reef environments. Amphisteginids and peneroplids were among the few taxa found in the bay environments, probably due to their preferences for phytal substrates and tolerance to moderate levels of eutrophication. The fringing reef environments along the outer bay are characterized by Borelis schlumbergeri, Heterostegina depressa, Textularia spp. and various miliolids which represent a hotspot of diversity within the complex reef-lagoon system of Moorea. The high foraminiferal Fisher α and species richness diversity in outer bay fringing reefs is consistent with the disturbance-mosaic (microhabitat heterogeneity) hypothesis. Calculations of the FORAM Index (FI), a single metric index to assess reef vitality, indicate that all fore- and most back-reef environments support active carbonate accretion and provide habitat suitability for carbonate producers dependent on algal symbiosis. Lowest suitability values were recorded within the innermost bays, an area where natural and increasing anthropogenic influences continue to impact the reefs. The presence of habitat specific assemblages and numerical abundance values of individual taxa show that benthic foraminifera are excellent recorders of environmental perturbations and good indicators useful in modern and ancient ecological and environmental studies.

Developing erosion models for integrated coastal zone management: a case study of The New Caledonia west coast.

PubMed

Dumas, Pascal; Printemps, Julia; Mangeas, Morgan; Luneau, Gaelle

2010-01-01

The tropical climate and human pressures (mining industry, forest fires) cause significant sediment inputs into the New Caledonia lagoon and are a major cause of degradation of the fringing reefs. The erosion process is spatially characterized on the west coast of New Caledonia to assess potential sediment inputs in the marine area. This paper describes the methodologies that are used to map soil sensitivity to erosion using remote sensing and a geographic information system tool. A cognitive approach, multi-criteria evaluation model and Universal Soil Loss Equation are implemented. This article compares the relevance of each model in order to spatialize and quantify potential erosion at catchment basin scale. These types of studies provide valuable results for focusing on areas subject to erosion and serve as a decision-making tool for the minimization of lagoon vulnerability to the natural and human dynamics on the level of the catchment basins. Copyright (c) 2010 Elsevier Ltd. All rights reserved.

A comparison between boat-based and diver-based methods for quantifying coral bleaching

USGS Publications Warehouse

Zawada, David G.; Ruzicka, Rob; Colella, Michael A.

2015-01-01

Recent increases in both the frequency and severity of coral bleaching events have spurred numerous surveys to quantify the immediate impacts and monitor the subsequent community response. Most of these efforts utilize conventional diver-based methods, which are inherently time-consuming, expensive, and limited in spatial scope unless they deploy large teams of scientifically-trained divers. In this study, we evaluated the effectiveness of the Along-Track Reef Imaging System (ATRIS), an automated image-acquisition technology, for assessing a moderate bleaching event that occurred in the summer of 2011 in the Florida Keys. More than 100,000 images were collected over 2.7 km of transects spanning four patch reefs in a 3-h period. In contrast, divers completed 18, 10-m long transects at nine patch reefs over a 5-day period. Corals were assigned to one of four categories: not bleached, pale, partially bleached, and bleached. The prevalence of bleaching estimated by ATRIS was comparable to the results obtained by divers, but only for corals > 41 cm in size. The coral size-threshold computed for ATRIS in this study was constrained by prevailing environmental conditions (turbidity and sea state) and, consequently, needs to be determined on a study-by-study basis. Both ATRIS and diver-based methods have innate strengths and weaknesses that must be weighed with respect to project goals.

Relative and combined effects of habitat and fishing on reef fish communities across a limited fishing gradient at Ningaloo.

PubMed

Wilson, Shaun K; Babcock, Russ C; Fisher, Rebecca; Holmes, Thomas H; Moore, James A Y; Thomson, Damian P

2012-10-01

Habitat degradation and fishing are major drivers of temporal and spatial changes in fish communities. The independent effects of these drivers are well documented, but the relative importance and interaction between fishing and habitat shifts is poorly understood, particularly in complex systems such as coral reefs. To assess the combined and relative effects of fishing and habitat we examined the composition of fish communities on patch reefs across a gradient of high to low structural complexity in fished and unfished areas of the Ningaloo Marine Park, Western Australia. Biomass and species richness of fish were positively correlated with structural complexity of reefs and negatively related to macroalgal cover. Total abundance of fish was also positively related to structural complexity, however this relationship was stronger on fished reefs than those where fishing is prohibited. The interaction between habitat condition and fishing pressure is primarily due to the high abundance of small bodied planktivorous fish on fished reefs. However, the influence of management zones on the abundance and biomass of predators and target species is small, implying spatial differences in fishing pressure are low and unlikely to be driving this interaction. Our results emphasise the importance of habitat in structuring reef fish communities on coral reefs especially when gradients in fishing pressure are low. The influence of fishing effort on this relationship may however become more important as fishing pressure increases. Copyright © 2012 Elsevier Ltd. All rights reserved.

Habitat degradation negatively affects auditory settlement behavior of coral reef fishes

PubMed Central

Harding, Harry R.; Wong, Kathryn E.; Merchant, Nathan D.; Meekan, Mark G.; Radford, Andrew N.; Simpson, Stephen D.

2018-01-01

Coral reefs are increasingly degraded by climate-induced bleaching and storm damage. Reef recovery relies on recruitment of young fishes for the replenishment of functionally important taxa. Acoustic cues guide the orientation, habitat selection, and settlement of many fishes, but these processes may be impaired if degradation alters reef soundscapes. Here, we report spatiotemporally matched evidence of soundscapes altered by degradation from recordings taken before and after recent severe damage on Australia’s Great Barrier Reef. Postdegradation soundscapes were an average of 15 dB re 1 µPa quieter and had significantly reduced acoustic complexity, richness, and rates of invertebrate snaps compared with their predegradation equivalents. We then used these matched recordings in complementary light-trap and patch-reef experiments to assess responses of wild fish larvae under natural conditions. We show that postdegradation soundscapes were 8% less attractive to presettlement larvae and resulted in 40% less settlement of juvenile fishes than predegradation soundscapes; postdegradation soundscapes were no more attractive than open-ocean sound. However, our experimental design does not allow an estimate of how much attraction and settlement to isolated postdegradation soundscapes might change compared with isolated predegradation soundscapes. Reductions in attraction and settlement were qualitatively similar across and within all trophic guilds and taxonomic groups analyzed. These patterns may lead to declines in fish populations, exacerbating degradation. Acoustic changes might therefore trigger a feedback loop that could impair reef resilience. To understand fully the recovery potential of coral reefs, we must learn to listen. PMID:29712839

Geochronology and subsurface stratigraphy of Pukapuka and Rakahanga atolls, Cook Islands: Late Quaternary reef growth and sea level history

USGS Publications Warehouse

Gray, S.C.; Hein, J.R.; Hausmann, R.; Radtke, U.

1992-01-01

Eustatic sea-level cycles superposed on thermal subsidence of an atoll produce layers of high sea-level reefs separated by erosional unconformities. Coral samples from these reefs from cores drilled to 50 m beneath the lagoons of Pukapuka and Rakahanga atolls, northern Cook Islands give electron spin resonance (ESR) and U-series ages ranging from the Holocene to 600,000 yr B.P. Subgroups of these ages and the stratigraphic position of their bounding unconformities define at least 5 periods of reef growth and high sea-level (0-9000 yr B.P., 125,000-180,000 yr B.P., 180,000-230,000 yr B.P., 300,000-460,000 yr B.P., 460,000-650,000 yr B.P.). Only two ages fall within error of the last interglacial high sea-level stand (???125,000-135,000 yr B.P.). This paucity of ages may result from extensive erosion of the last intergracial reef. In addition, post-depositional isotope exchange may have altered the time ages of three coral samples to apparent ages that fall within glacial stage 6. For the record to be preserved, vertical accretion during rising sea-level must compensate for surface lowering from erosion during sea-level lowstands and subsidence of the atoll; erosion rates (6-63 cm/1000 yr) can therefore be calculated from reef accretion rates (100-400 cm/1000 yr), subsidence rates (2-6 cm/1000 yr), and the duration of island submergence (8-15% of the last 600,000 yr). The stratigraphy of coral ages indicates island subsidence rates of 4.5 ?? 2.8 cm/1000 yr for both islands. A model of reef growth and erosion based on the stratigraphy of the Cook Islands atolls suggests average subsidence and erosion rates of between 3-6 and 15-20 cm/1000 yr, respectively. ?? 1992.

Post-Disturbance Stability of Fish Assemblages Measured at Coarse Taxonomic Resolution Masks Change at Finer Scales.

PubMed

Ceccarelli, Daniela M; Emslie, Michael J; Richards, Zoe T

2016-01-01

Quantifying changes to coral reef fish assemblages in the wake of cyclonic disturbances is challenging due to spatial variability of damage inherent in such events. Often, fish abundance appears stable at one spatial scale (e.g. reef-wide), but exhibits substantial change at finer scales (e.g. site-specific decline or increase). Taxonomic resolution also plays a role; overall stability at coarse taxonomic levels (e.g. family) may mask species-level turnover. Here we document changes to reef fish communities after severe Tropical Cyclone Ita crossed Lizard Island, Great Barrier Reef. Coral and reef fish surveys were conducted concurrently before and after the cyclone at four levels of exposure to the prevailing weather. Coral cover declined across all exposures except sheltered sites, with the largest decline at exposed sites. There was no significant overall reduction in the total density, biomass and species richness of reef fishes between 2011 and 2015, but individual fish taxa (families and species) changed in complex and unpredictable ways. For example, more families increased in density and biomass than decreased following Cyclone Ita, particularly at exposed sites whilst more fish families declined at lagoon sites even though coral cover did not decline. All sites lost biomass of several damselfish species, and at most sites there was an increase in macroinvertivores and grazers. Overall, these results suggest that the degree of change measured at coarse taxonomic levels masked high species-level turnover, although other potential explanations include that there was no impact of the storm, fish assemblages were impacted but underwent rapid recovery or that there is a time lag before the full impacts become apparent. This study confirms that in high-complexity, high diversity ecosystems such as coral reefs, species level analyses are essential to adequately capture the consequences of disturbance events.

Effects of Coral Reef Benthic Primary Producers on Dissolved Organic Carbon and Microbial Activity

PubMed Central

Haas, Andreas F.; Nelson, Craig E.; Wegley Kelly, Linda; Carlson, Craig A.; Rohwer, Forest; Leichter, James J.; Wyatt, Alex; Smith, Jennifer E.

2011-01-01

Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC) release were assessed for several common benthic reef organisms from the backreef habitat. We assessed microbial community response to dissolved exudates of each benthic producer by measuring bacterioplankton growth, respiration, and DOC drawdown in two-day dark dilution culture incubations. Experiments were conducted for six benthic producers: three species of macroalgae (each representing a different algal phylum: Turbinaria ornata – Ochrophyta; Amansia rhodantha – Rhodophyta; Halimeda opuntia – Chlorophyta), a mixed assemblage of turf algae, a species of crustose coralline algae (Hydrolithon reinboldii) and a dominant hermatypic coral (Porites lobata). Our results show that all five types of algae, but not the coral, exuded significant amounts of labile DOC into their surrounding environment. In general, primary producers with the highest rates of photosynthesis released the most DOC and yielded the greatest bacterioplankton growth; turf algae produced nearly twice as much DOC per unit surface area than the other benthic producers (14.0±2.8 µmol h−1 dm−2), stimulating rapid bacterioplankton growth (0.044±0.002 log10 cells h−1) and concomitant oxygen drawdown (0.16±0.05 µmol L−1 h−1 dm−2). Our results demonstrate that benthic reef algae can release a significant fraction of their photosynthetically-fixed carbon as DOC, these release rates vary by species, and this DOC is available to and consumed by reef associated microbes. These data provide compelling evidence that benthic primary producers differentially influence reef microbial dynamics and biogeochemical parameters (i.e., DOC and oxygen availability, bacterial abundance and metabolism) in coral reef communities. PMID:22125645

Net Ecosystem Calcification by a Coral Reef Community under Natural Acidification

NASA Astrophysics Data System (ADS)

Shamberger, K.; Lentz, S. J.; Cohen, A. L.

2016-02-01

Net Ecosystem Calcification (NEC) is a measure of the balance between calcium carbonate production (calcification) and loss (dissolution) within a coral reef system. Establishing baseline NEC estimates for a broad range of coral reef systems today provides much needed information to constrain spatial and temporal variability within and amongst different systems, investigate the sensitivity of ecosystem scale calcification to environmental forcing, and improve projections of coral reef futures under ocean acidification throughout this century. Previous NEC studies have been limited to coral reefs with unidirectional (Lagrangian and flow respirometry studies) or negligible (slack water Eulerian studies) water flow across the reef for at least part of the day, usually on the order of hours. Here, we present NEC rates in a naturally low pH, semi-enclosed coral reef lagoon with high coral cover and diversity and tidally driven flow within the Palau Rock Islands. NEC was determined from data collected over the full diel cycle for four consecutive days, during two successive years and different seasons, using total alkalinity (TA), salinity, and volume budgets. Two different methods used to calculate NEC are in good agreement and show that the coral community is net calcifying despite high rates of bioerosion and pH (mean pH = 7.88 ± 0.02) and aragonite saturation state (Ωar = 2.66 ± 0.11) levels close to those projected for the end of this century. Critically, NEC rates in year 1 (17.0 - 23.7 mmol m-2 d-1) were half those of year 2 (42.0 - 48.1 mmol m-2 d-1), though the carbonate chemistry of the source water did not change between years. This suggests that single occupations and short term measurements do not adequately capture the full range of NEC variability within a system and that factors other than ocean acidification play an important role in modulating NEC rates.

Post-Disturbance Stability of Fish Assemblages Measured at Coarse Taxonomic Resolution Masks Change at Finer Scales

PubMed Central

Ceccarelli, Daniela M.

2016-01-01

Quantifying changes to coral reef fish assemblages in the wake of cyclonic disturbances is challenging due to spatial variability of damage inherent in such events. Often, fish abundance appears stable at one spatial scale (e.g. reef-wide), but exhibits substantial change at finer scales (e.g. site-specific decline or increase). Taxonomic resolution also plays a role; overall stability at coarse taxonomic levels (e.g. family) may mask species-level turnover. Here we document changes to reef fish communities after severe Tropical Cyclone Ita crossed Lizard Island, Great Barrier Reef. Coral and reef fish surveys were conducted concurrently before and after the cyclone at four levels of exposure to the prevailing weather. Coral cover declined across all exposures except sheltered sites, with the largest decline at exposed sites. There was no significant overall reduction in the total density, biomass and species richness of reef fishes between 2011 and 2015, but individual fish taxa (families and species) changed in complex and unpredictable ways. For example, more families increased in density and biomass than decreased following Cyclone Ita, particularly at exposed sites whilst more fish families declined at lagoon sites even though coral cover did not decline. All sites lost biomass of several damselfish species, and at most sites there was an increase in macroinvertivores and grazers. Overall, these results suggest that the degree of change measured at coarse taxonomic levels masked high species-level turnover, although other potential explanations include that there was no impact of the storm, fish assemblages were impacted but underwent rapid recovery or that there is a time lag before the full impacts become apparent. This study confirms that in high-complexity, high diversity ecosystems such as coral reefs, species level analyses are essential to adequately capture the consequences of disturbance events. PMID:27285160

Spatial Patterns in Herbivory on a Coral Reef Are Influenced by Structural Complexity but Not by Algal Traits

PubMed Central

Vergés, Adriana; Vanderklift, Mathew A.; Doropoulos, Christopher; Hyndes, Glenn A.

2011-01-01

Background Patterns of herbivory can alter the spatial structure of ecosystems, with important consequences for ecosystem functions and biodiversity. While the factors that drive spatial patterns in herbivory in terrestrial systems are well established, comparatively less is known about what influences the distribution of herbivory in coral reefs. Methodology and Principal Findings We quantified spatial patterns of macroalgal consumption in a cross-section of Ningaloo Reef (Western Australia). We used a combination of descriptive and experimental approaches to assess the influence of multiple macroalgal traits and structural complexity in establishing the observed spatial patterns in macroalgal herbivory, and to identify potential feedback mechanisms between herbivory and macroalgal nutritional quality. Spatial patterns in macroalgal consumption were best explained by differences in structural complexity among habitats. The biomass of herbivorous fish, and rates of herbivory were always greater in the structurally-complex coral-dominated outer reef and reef flat habitats, which were also characterised by high biomass of herbivorous fish, low cover and biomass of macroalgae and the presence of unpalatable algae species. Macroalgal consumption decreased to undetectable levels within 75 m of structurally-complex reef habitat, and algae were most abundant in the structurally-simple lagoon habitats, which were also characterised by the presence of the most palatable algae species. In contrast to terrestrial ecosystems, herbivory patterns were not influenced by the distribution, productivity or nutritional quality of resources (macroalgae), and we found no evidence of a positive feedback between macroalgal consumption and the nitrogen content of algae. Significance This study highlights the importance of seascape-scale patterns in structural complexity in determining spatial patterns of macroalgal consumption by fish. Given the importance of herbivory in maintaining the ability of coral reefs to reorganise and retain ecosystem functions following disturbance, structural complexity emerges as a critical feature that is essential for the healthy functioning of these ecosystems. PMID:21347254

Carbonate sedimentology of Seribu Islands patch reef complex: a literature review

NASA Astrophysics Data System (ADS)

Utami, D. A.; Hakim, A. R.

2018-02-01

Many oil and gas reservoirs in the world are reserved in fossil carbonate sediment. Knowledge of modern carbonate sedimentology is important for a better understanding of ancient carbonate sedimentation. Equatorial coral reefs comprise almost half of the world coral reef production, and yet their dynamics, distributions, and cycles are still not well understood. Contrary to their subtropical counterpart, South East Asian carbonate system is known to be strongly influenced by the combination of oceanographic and climatic conditions. Hence carbonate sediments in the tropics have a distinct depositional system, and ought to be treated differently since common distribution models were developed from the (sub-tropical) Atlantic and Pacific regions. This paper systematically summarizes carbonate sediment studies in Seribu Islands and its dominant oceanographic configuration to provide insights and a sense of research direction in the future.

Persistence and Change in Community Composition of Reef Corals through Present, Past, and Future Climates

PubMed Central

Edmunds, Peter J.; Adjeroud, Mehdi; Baskett, Marissa L.; Baums, Iliana B.; Budd, Ann F.; Carpenter, Robert C.; Fabina, Nicholas S.; Fan, Tung-Yung; Franklin, Erik C.; Gross, Kevin; Han, Xueying; Jacobson, Lianne; Klaus, James S.; McClanahan, Tim R.; O'Leary, Jennifer K.; van Oppen, Madeleine J. H.; Pochon, Xavier; Putnam, Hollie M.; Smith, Tyler B.; Stat, Michael; Sweatman, Hugh; van Woesik, Robert; Gates, Ruth D.

2014-01-01

The reduction in coral cover on many contemporary tropical reefs suggests a different set of coral community assemblages will dominate future reefs. To evaluate the capacity of reef corals to persist over various time scales, we examined coral community dynamics in contemporary, fossil, and simulated future coral reef ecosystems. Based on studies between 1987 and 2012 at two locations in the Caribbean, and between 1981 and 2013 at five locations in the Indo-Pacific, we show that many coral genera declined in abundance, some showed no change in abundance, and a few coral genera increased in abundance. Whether the abundance of a genus declined, increased, or was conserved, was independent of coral family. An analysis of fossil-reef communities in the Caribbean revealed changes in numerical dominance and relative abundances of coral genera, and demonstrated that neither dominance nor taxon was associated with persistence. As coral family was a poor predictor of performance on contemporary reefs, a trait-based, dynamic, multi-patch model was developed to explore the phenotypic basis of ecological performance in a warmer future. Sensitivity analyses revealed that upon exposure to thermal stress, thermal tolerance, growth rate, and longevity were the most important predictors of coral persistence. Together, our results underscore the high variation in the rates and direction of change in coral abundances on contemporary and fossil reefs. Given this variation, it remains possible that coral reefs will be populated by a subset of the present coral fauna in a future that is warmer than the recent past. PMID:25272143

Porosity evolution of upper Miocene reefs, Almeria Province, southern Spain

USGS Publications Warehouse

Armstrong, A.K.; Snavely, P.D.; Addicott, W.O.

1980-01-01

Sea cliffs 40 km east of Almeria, southeastern Spain, expose upper Miocene reefs and patch reefs of the Plomo formation. These reefs are formed of scleractinian corals, calcareous algae, and mollusks. The reef cores are as much as 65 m thick and several hundred meters wide. Fore-reef talus beds extend 1,300 m across and are 40 m thick. The reefs and reef breccias are composed of calcific dolomite. They lie on volcanic rocks that have a K-Ar date of 11.5 m.y. and in turn are overlain by the upper Miocene Vicar Formation. In the reef cores and fore-reef breccia beds, porosity is both primary and postdepositional. Primary porosity is of three types: (a) boring clam holes in the scleractinian coral heads, cemented reef rocks, and breccias; (b) intraparticle porosity within the corals, Halimeda plates, and vermetid worm tubes; and (c) interparticle porosity between bioclastic fragments and in the reef breccia. Postdepositional moldic porosity was formed by the solution of aragonitic material such as molluscan and coral fragments. The Plomo reef carbonate rocks have high porosity and permeability, and retain a great amount of depositional porosity. Pores range in size from a few micrometers to 30 cm. The extensive intercrystalline porosity and high permeability resulted from dolomitization of micritic matrix. Dolomite rhombs are between 10 and 30 μ across. More moldic porosity was formed by the dissolution of the calclte bioclasts. Some porosity reduction has occurred by incomplete and partial sparry calcite infilling of interparticular, moldic, and intercrystalline voids. The high porosity and permeability of these reefs make them important targets for petroleum exploration in the western Mediterranean off southern Spain. In these offshore areas in the subsurface the volcanic ridge and the Plomo reef complex are locally onlapped or overlapped by 350 m or more of Miocene(?) and Pliocene fine-grained sedimentary rocks. The possibility exists that the buried Plomo reef deposits may form traps for oil and gas in the offshore areas southwest of the type locality. Stratigraphic traps also may occur where the Neogene sequence above the Plomo reef complex onlaps the volcanic ridge.

δ15N in the turtle grass from the Mexican Caribbean

NASA Astrophysics Data System (ADS)

Talavera-Saenz, A.; Sanchez, A.; Ortiz-Hernandez, M.

2013-05-01

Nutrient inputs associated with population growth threaten the integrity of coastal ecosystems. To assess the rapid increase in tourism, we compared the δ15N from Thalassia testudinum collected at sites with different levels of tourism development and population to detect the N inputs of wastewater discharge (WD) along the coast of Quintana Roo. The contributions of nitrogen enriched in 15N are directly related to the increase of WD inputs in areas of high tourism development (Nichupte Lagoon in Cancun, >3 million tourists per year from 2007 to 2011 and 0.7 million of resident population) and decreased towards Bahia Akumal and Tulum (>3 million tourists per year from 2007 to 2011 and 0.15 million of resident population). The δ15N from T. testudinum was significantly lower at Mahahual and Puerto Morelos (about 0.4 million tourists per year in 2007 to 2011 and 0.25 million of resident population) than other the sites. In areas of the lowest development and with tourist activity restricted and small population, such as the Yum Balam Reserve and Sian Ka'an Biosphere Reserve, the δ15N values were in much higher enrichment that Mahahual and Puerto Morelos. Therefore is suggested that Mahahual and Puerto Morelos may be used for baseline isotopic monitoring, over environmental pressure on the reef lagoon ecosystem, where tourist activities and population are growing very slow rate. The anthropogenic N input has the potential to impact, both environmentally and economically, the seagrass meadows and the coral reefs along the coast of Quintana Roo and the Caribbean.

Role of Sediments and Nutrients in the Condition of a Coral Reef Under Tourist Pressure: Akumal México.

NASA Astrophysics Data System (ADS)

Naranjo-Garcia, M. J.; Vadés Lozano, D. S.; Real-De-Leon, E.; Lopez-Aguiar, K.; Garza-Perez, J. R.

2014-12-01

Akumal, Mexico, was the first tourist resort in the Mexican Caribbean mainland, its highly developed coastal zone lies directly above the phreatic, and it is directly connected to the sub-littoral waters. Akumal is also known as a well-developed fringing coral reef, now in a critical condition. The main objective of this study was to explore the relationship between two of the main indicators of human pressure (nutrients and sedimentation, linked to coastal development and water run-offs) and the condition of the reef benthos, during a year. The sampling design used four transects perpendicular to shore, associated to different tourist and water run-off exposure, for a total of 12 stations distributed in three different reef zones (transition zone, shallow and deep spurs and grooves). Monthly samples were collected: water samples close to the reef lagoon drain channels and at bottom depth at each station, and sediment traps were recovered and replaced also at each station. Reef Benthos videotransects were recorded bi-monthly at each station to assess its condition. Macroalgae and filamentous algae dominate benthic cover (up to 50%), hard-coral cover ranges from 5-9%. Five coral-diseases were recorded, affecting 10.16% of the coral colonies: Caribbean Ciliate Infection, White Band, Purple Spots, White Spots and Yellow Band. The sedimentation rate -sr- ranged from 0.13 to 83.7 mg/cm2/day during the year; 86% of the samples had a sr ≤ 10 mg/cm2/day (reefs not stressed); 13% of the samples had a sr ranging from 10 to 50 mg/cm2/day (stressed reefs); and 1% of the samples were over the critical threshold (>50 mg/cm2/day). Dissolved Inorganic Nitrogen concentrations during the year were above those recorded previously in Caribbean reefs. The most abundant fraction was ammonium, surpassing both Mexican norms: For protection of aquatic life in coastal zones (0.01 mg/L), and the critical threshold for aquatic life (0.4 mg/L). These concentration limits are considered as drivers of eutrophication, one of the main established causes of reef degradation globally. High concentrations of ammonium and other nutrients have been linked to increases in algae cover and coral diseases incidence, and to decreases in rates of coral calcification, fertility, production and viability of coral larvae, and the associated diversity loss.

Tikehau Atoll, French Polynesia

NASA Image and Video Library

2017-12-08

The islands and coral atolls of French Polynesia, located in the southern Pacific Ocean, epitomize the idea of tropical paradise: white sandy beaches, turquoise lagoons, and palm trees. Even from the distance of space, the view of these atolls is beautiful. This image from the Advanced Land Imager on NASA’s Earth Observing-1 (EO-1) satellite shows the southern part of Tikehau Atoll, one of the 78 coral atolls that make up the Tuamotu Archipelago. Patches of coral make star-like spots across the turquoise expanse of the lagoon. A line of tree-covered islets encircles the lagoon. At the southernmost tip of the atoll, a large islet accommodates a small village and an air strip. NASA image created by Jesse Allen, using EO-1 ALI data provided courtesy of the NASA EO-1 Team. Caption by Rebecca Lindsey. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

Artificial soft sediment resuspension and high density opportunistic macroalgal mat fragmentation as method for increasing sediment zoobenthic assemblage diversity in a eutrophic lagoon.

PubMed

Martelloni, Tatiana; Tomassetti, Paolo; Gennaro, Paola; Vani, Danilo; Persia, Emma; Persiano, Marco; Falchi, Riccardo; Porrello, Salvatore; Lenzi, Mauro

2016-09-15

Superficial soft sediment resuspension and partial fragmentation of high density opportunistic macroalgal mats were investigated by boat to determine the impact on zoobenthic assemblages in a eutrophic Mediterranean lagoon. Sediment resuspension was used to oxidise superficial organic sediments as a method to counteract the effects of eutrophication. Likewise, artificial decay of macroalgal mat was calculated to reduce a permanent source of sediment organic matter. An area of 9ha was disturbed (zone D) and two other areas of the same size were left undisturbed (zones U). We measured chemical-physical variables, estimated algal biomass and sedimentary organic matter, and conducted qualitative and quantitative determinations of the zoobenthic species detected in sediment and among algal mats. The results showed a constant major reduction in labile organic matter (LOM) and algal biomass in D, whereas values in U remained stable or increased. In the three zones, however, bare patches of lagoon bed increased in size, either by direct effect of the boats in D or by anaerobic decay of the algal mass in U. Zoobenthic assemblages in algal mats reduced the number of species in D, probably due to the sharp reduction in biomass, but remained stable in U, whereas in all three areas abundance increased. Sediment zoobenthic assemblages increased the number of species in D, as expected, due to drastic reduction in LOM, whereas values in U remained stable and again abundance increased in all three zones. In conclusion, we confirmed that reduction of sediment organic load enabled an increase in the number of species, while the algal mats proved to be an important substrate in the lagoon environment for zoobenthic assemblages, especially when mat alternated with bare intermat areas of lagoon bed. Sediment resuspension is confirmed as a management criterion for counteracting the effects of eutrophication and improving the biodiversity of zoobenthic assemblages in eutrophic lagoon environments. Copyright © 2016 Elsevier Ltd. All rights reserved.

Presence of Panulirus argus virus 1 (PaV1) in juvenile spiny lobsters Panulirus argus from the Caribbean coast of Mexico.

PubMed

Huchin-Mian, Juan Pablo; Rodríguez-Canul, Rossanna; Arias-Bañuelos, Efrain; Simá-Alvarez, Raúl; Pérez-Vega, Juan A; Briones-Fourzán, Patricia; Lozano-Alvarez, Enrique

2008-04-01

Macroscopic evidence, histological sections, transmission electron microscopy (TEM) evaluation, and PCR analyses of 25 apparently diseased juvenile spiny lobsters Panulirus argus from the reef lagoon of Puerto Morelos, Mexico, showed the presence of Panulirus argus Virus 1 (PaV1). Cowdry Type A intranuclear viral inclusions were observed in histological analyses, icosahedral viral particles were observed by TEM, and PCR using specific primers for PaV1 amplified a fragment of 499 bp. This is the first report of PaV1 infecting P. argus outside the Florida Keys, USA.

The northernmost coral frontier of the Maldives: The coral reefs of Ihavandippolu Atoll under long-term environmental change.

PubMed

Tkachenko, Konstantin S

2012-12-01

Ihavandippolu, the northernmost atoll of the Maldives, experienced severe coral bleaching and mortality in 1998 followed by several bleaching episodes in the last decade. Coral cover in the 11 study sites surveyed in July-December of 2011 in the 3-5 m depth range varied from 1.7 to 51%. Reefs of the islands located in the center of Ihavandippolu lagoon have exhibited a very low coral recovery since 1998 and remain mostly degraded 12 years after the impact. At the same time, some reefs, especially in the inner part of the eastern ring of the atoll, demonstrate a high coral cover (>40%) with a dominance of branching Acropora that is known to be one of the coral genera that is most susceptible to thermal stress. The last severe bleaching event in 2010 resulted in high coral mortality in some sites of the atoll. Differences in coral mortality rates and proportion between "susceptible" and "resistant" taxa in study sites are apparently related to long-term adaptation and local hydrological features that can mitigate thermal impacts. Abundant herbivorous fish observed in the atoll prevent coral overgrowth by macroalgae even on degraded reefs. Despite the frequent influence of temperature anomalies and having less geomorphologic refuges for coral survivals than other larger Maldivian atolls, a major part of observed coral communities in Ihavandippolu Atoll exhibits high resilience and potential for further acclimatization to a changing environment. Copyright © 2012 Elsevier Ltd. All rights reserved.

Wind-induced circulation in a large tropical lagoon: Chetumal Bay

NASA Astrophysics Data System (ADS)

Palacios, E.; Carrillo, L.

2013-05-01

Chetumal Bay is a large tropical lagoon located at the Mesoamerican Reef System. Windinduced circulation in this basin was investigated by using direct measurements of current, sea level, and 2d barotropic numerical model. Acoustic Doppler Profiler (ADP) transects covering the north of Chetumal Bay during two campaigns September 2006 and March 2007 were used. The 2d barotropic numerical model was ROMs based and wind forced. Wind information was obtained from a meteorological station located at ECOSUR Chetumal. Sea level data was collected from a pressure sensor deployed in the lagoon. A seasonal pattern of circulation was observed. From observations, during September 2006, a northward flow was shown in most part of the bay and a southward flow in the eastern coast was observed with velocities ranged from 6 cm s-1 to 36 cm s-1. In March 2007, the current pattern was more complex; divergences and converges were identified. The dominant circulation was northward in eastern portion, and southward in the central and western zone. The average current speed was 6 cm s-1 with maximum values of 26 -34 cm s-1. During September 2006 predominant wind was easternsoutheastern and during March 2007, northerly wind events were recorded. Sea level amplitude responded quickly to changes in the magnitude and direction of the wind. Results of sea level and circulation from the 2d barotropic numerical model agreed with observations at first approximation.

Holocene evolution of Dahab coastline - Gulf of Aqaba, Sinai Peninsula, Egypt

NASA Astrophysics Data System (ADS)

Torab, Magdy

2018-03-01

Dahab is a little Bedouin-village in Sinai Peninsula on the east coast of the Gulf of Aqaba and it lies approximately 90 km north of Sharm-el-Sheikh City. Dahab means "gold" in the Arabic language; over the past 20 years it has become one of the most visited tourist sites in Egypt. The basement complex is composed mostly of biotite aplite-granite, mica-aplite granite, granodiorite, quartz diorite, alaskite, and diorite. This composition correlates to similar igneous rocks in the most southern areas of Sinai and the Red Sea. Wadi Dahab is composed of igneous and metamorphic rocks and the coastline is formed of fragments of its rocks mixed with fragments of coral reef. The morphology of Dahab's coastline is characterized by a hooked marine spit composed of fluvial sediments carried by marine currents from the mouth of Wadi Dahab. This spit encloses a shallow lagoon, but the active deposition on the lagoon bottom will turn it into saline marsh. This paper investigates the evolution of the Dahab spit and lagoon during the Holocene and over the last 100 years, as well as the potential impacts of future management of the coastal area. The coastline mapping during the study was dependent on GIS techniques and data were collected by using total station, aerial photographs and satellite image interpretation as well as soil sample dating.

Habitat degradation negatively affects auditory settlement behavior of coral reef fishes.

PubMed

Gordon, Timothy A C; Harding, Harry R; Wong, Kathryn E; Merchant, Nathan D; Meekan, Mark G; McCormick, Mark I; Radford, Andrew N; Simpson, Stephen D

2018-05-15

Coral reefs are increasingly degraded by climate-induced bleaching and storm damage. Reef recovery relies on recruitment of young fishes for the replenishment of functionally important taxa. Acoustic cues guide the orientation, habitat selection, and settlement of many fishes, but these processes may be impaired if degradation alters reef soundscapes. Here, we report spatiotemporally matched evidence of soundscapes altered by degradation from recordings taken before and after recent severe damage on Australia's Great Barrier Reef. Postdegradation soundscapes were an average of 15 dB re 1 µPa quieter and had significantly reduced acoustic complexity, richness, and rates of invertebrate snaps compared with their predegradation equivalents. We then used these matched recordings in complementary light-trap and patch-reef experiments to assess responses of wild fish larvae under natural conditions. We show that postdegradation soundscapes were 8% less attractive to presettlement larvae and resulted in 40% less settlement of juvenile fishes than predegradation soundscapes; postdegradation soundscapes were no more attractive than open-ocean sound. However, our experimental design does not allow an estimate of how much attraction and settlement to isolated postdegradation soundscapes might change compared with isolated predegradation soundscapes. Reductions in attraction and settlement were qualitatively similar across and within all trophic guilds and taxonomic groups analyzed. These patterns may lead to declines in fish populations, exacerbating degradation. Acoustic changes might therefore trigger a feedback loop that could impair reef resilience. To understand fully the recovery potential of coral reefs, we must learn to listen. Copyright © 2018 the Author(s). Published by PNAS.

Resilience of branching and massive corals to wave loading under sea level rise--a coupled computational fluid dynamics-structural analysis.

PubMed

Baldock, Tom E; Karampour, Hassan; Sleep, Rachael; Vyltla, Anisha; Albermani, Faris; Golshani, Aliasghar; Callaghan, David P; Roff, George; Mumby, Peter J

2014-09-15

Measurements of coral structural strength are coupled with a fluid dynamics-structural analysis to investigate the resilience of coral to wave loading under sea level rise and a typical Great Barrier Reef lagoon wave climate. The measured structural properties were used to determine the wave conditions and flow velocities that lead to structural failure. Hydrodynamic modelling was subsequently used to investigate the type of the bathymetry where coral is most vulnerable to breakage under cyclonic wave conditions, and how sea level rise (SLR) changes this vulnerability. Massive corals are determined not to be vulnerable to wave induced structural damage, whereas branching corals are susceptible at wave induced orbital velocities exceeding 0.5m/s. Model results from a large suite of idealised bathymetry suggest that SLR of 1m or a loss of skeleton strength of order 25% significantly increases the area of reef flat where branching corals are exposed to damaging wave induced flows. Copyright © 2014 Elsevier Ltd. All rights reserved.

Proximate environmental drivers of coral communities at Palmyra Atoll: establishing baselines prior to removing a WWII military causeway.

PubMed

Williams, Gareth J; Knapp, Ingrid S; Maragos, James E; Davy, Simon K

2011-08-01

A management proposal aims to partly remove a WWII military causeway at Palmyra Atoll to improve lagoon water circulation and alleviate sedimentation stress on the southeast backreef, an area of high coral cover and diversity. This action could result in a shift in sedimentation across reef sites. To provide management advice, we quantified the proximate environmental factors driving scleractinian coral cover and community patterns at Palmyra. The proportion of fine sedimentation was the optimal predictor of coral cover and changes in community structure, explaining 23.7% and 24.7% of the variation between sites, respectively. Scleractinian coral cover was negatively correlated with increases in fine sedimentation. Removing the causeway could negatively affect the Montipora corals that dominate the western reef terrace, as this genus was negatively correlated with levels of fine sedimentation. The tolerance limits of corals, and sediment re-distribution patterns, should be determined prior to complete removal of the causeway. Copyright © 2011 Elsevier Ltd. All rights reserved.

Hydrocarbons in the sediments of the Bermuda region lagoonal to abyssal depths

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sletter, T.D.; Butler, J.N.; Barbash, J.E.

1980-01-01

Gas chromatographic analyses of the pentane fraction derived from surface sediments collected from 20 stations (50 cores) around Bermuda from the subtidal zone to 40 m depth and one deep-water sediment sample from 1400 m depth showed that outside the protective boiler reef, the total aliphatic (pentane-extractable) hydrocarbon content was less than inside the reef (3-10 jg/g dry weight outside vs. 10-65 jg/g inside). Samples from the 1400 m depth showed < 1.0 jg/g aliphatic hydrocarbon content. The chromatograms from the shipping channels showed fresh petroleum source concentrations of 8-31 jg/g; harbors yielded chromatograms typical of chronic petroleum contamination, withmore » 30-110 jg/g concentrations. Several biogenic compounds (including C15 and C17 n-alkanes and most probably derived from marine algae) were observed, in addition to the petroleum-derived hydrocarbons. The criteria adopted for distinguishing biogenic and petroleum hydrocarbons are given.« less

Modeled atoll shoreline and run-up changes in response to sea-level rise and varying large wave conditions at Wake and Midway Atolls, Northwestern Hawaiian Islands

NASA Astrophysics Data System (ADS)

Shope, J. B.; Storlazzi, C. D.; Hoeke, R. K.

2016-12-01

Atoll islands are dynamic features that respond to seasonal alterations in wave conditions and sea level. With sea level and wave climates projected to change over the next century, it is unclear how shoreline wave runup and erosion patterns along these low elevation islands will respond, making it difficult for communities to prepare for the future. To investigate this, extreme boreal winter and summer wave conditions under a variety of future sea-level rise (SLR) scenarios were modeled at two atolls, Wake and Midway, using Delft3D. Nearshore wave conditions were used to find the potential longshore sediment flux, and wave-driven shoreline erosion was calculated as the divergence of the longshore drift; runup and the locations where runup exceed the berm elevation were also found. Of the aforementioned parameters, SLR is projected to be the dominant force driving future island morphological change and flooding. Increased sea level reduces depth-limited breaking by the atoll reef, allowing larger waves to reach the shoreline, increasing runup height and driving greater inland flooding along most coastlines. Previously protected shorelines, such as lagoon shorelines or shorelines with comparably wide reef flats, are projected see the greatest relative increases in runup. Increases in inland flooding extent were greatest along seaward shorelines due to increases in runup. Changes in incident wave directions had a smaller effect on runup, and the projected changes to incident wave heights had a negligible effect. SLR also drove the greatest changes to island shoreline morphology. Windward islands are projected to become thinner as seaward and lagoonal shorelines erode, accreting toward more leeward shorelines and shorelines with comparably wider reef flats. Similarly, leeward islands are anticipated to become thinner and longer, accreting towards their longitudinal ends. The shorelines of these islands will likely change dramatically over the next century as SLR and altered wave climates drive new erosional regimes. It is vital to the sustainability of island communities that the relative magnitudes of these effects are addressed when planning for projected future climates.

A Comprehensive Study on Coastline Process and Sedimentary Dynamics, Sardinera Beach, Mona Island, P.R.

NASA Astrophysics Data System (ADS)

Rodriguez-Delga, A. M.; Ramirez, W. R.

2008-12-01

Sardinera beach in Mona Island, Puerto Rico, has a great recreational and ecological value and is an important research place to gather information on shoreline processes in an area far from the main land and with only scarce man made influences. Beach rock exposures present along the shoreline in Sardinera Beach have increased considerably during the last decade. A new management plan is being developed for Mona Island and the Department of Natural Resources (DNRA) of Puerto Rico wants to better understand the beach sand dynamics on this and other Mona Island beaches. This research includes field and laboratory work that characterize coastal sedimentary processes and helps to better understand the shoreline changes as well as seasonal variations in sand movement and composition. This work also establish the logistics and methodology basis for further studies that will expand to other Mona Island beaches. Benchmarks, GPS coordinates, and landmarks were used to establish ten permanent beach profiles along Sardinera Beach. Beach profiles were (and will be) measured monthly. Sardinera Beach sands are composed mostly of carbonate (CaCO3) components, products of the combination of biological, chemical and diagenetic processes, high grade of micritization, and of lithic limestone fragments. Sand composition differences between Sardinera Beach, the Mona Shelf and adjacent beach, reef crest and reef lagoon systems suggest Sardinera sands are not replenished by the modern marine components produced in these environments. The input of "fresh bioclasts" in this beach seems to be limited by natural (beach rock) and mane made (dock) barriers along the shore and by alteration in the current patterns produced by the man made aperture of the reef. Sardinera's micritized and recrystalized sand deposits seem to have been re-transported between the reefal lagoon and the beach. Sand volume analysis indicates a total sand loss of 1,322 m3 between the months of September to April. Aerial images from the years 1977, 1992 and 2003 show 14 to 27 meters of recession along the coast line.

The geomorphology and hydrogeology of the karstic Islands Maratua, East Kalimantan, Indonesia: the potential and constraints for tourist destination development

NASA Astrophysics Data System (ADS)

Haryono, E.; Sasongko, M. H. D.; Barianto, D. H.; Setiawan, J. B.; Hakim, A. A.; Zaenuri, A.

2018-04-01

Maratua Island is one of the islands of Berau District, East Kalimantan which has great potential of natural beauty for tourism development. The area currently is one of famous tourist destination in East Kalimantan which is a carbonate reef built-up or so-called karst island. This paper is an endeavor 1) to unveil geomorphological and hydrogeological characteristics of the island, and 2) to recommend Island development as a tourist destination. Maratua Island is a V shape atoll with the open lagoon. Six geomorphological units were found on the island, i.e., fringing reef, beach, marine terrace, karst ridge, structural valley, and lagoon. Caves are also found in the karst ridge and the coast as an inundated passage. Three structural depressions in the karst ridge are other unique geomorphological feature in the area of which a marine lake environment with jellyfish is inhabited. The island is typified by two different aquifer units, i.e., porous media and fractured media aquifer. Porous aquifer lies on the beach of Boibukut area. Fractured-aquifer characterizes the other geomorphological units in the area. Freshwater accordingly is found in the beach area with a limited amount. Unfortunately, the groundwater in the marine terrace and karst ridge are saline. Maratua Island has enormous potential for tourism destination development. The major tourist activities in the area based on the geomorphological unit are snorkeling and diving (in fringing reef and lagoo n), hiking, cave exploration and marine lake exploration and cave diving (in karst ridge and structural valley); recreation and picnic (beach). The major limitation in the area is a shortage of freshwater resource and land. Limited water supply should be extracted from the beach area of Bohe Bukut village. Groundwater extraction from the beach area of Bohe Bukut must be for drinking water only. Supply of drinking water should be substituted from collected rainwater or desalination from sea water and water in the cave. Restrictions in the number of visitors and lodging development should also be considered.

Describing the environmental fate of diuron in a tropical river catchment.

PubMed

Camenzuli, Louise; Scheringer, Martin; Gaus, Caroline; Ng, Carla A; Hungerbühler, Konrad

2012-12-01

The use of the herbicide diuron on sugarcane fields along the river catchments of the Great Barrier Reef (GBR) in Australia is an issue of concern due to high levels of diuron reported in the GBR lagoon, and has recently led to a restriction on the use of diuron during the 2011/12 wet season. An important question in this context is how much diuron is mobilised from the agricultural area by strong rainfall and floods in the wet season and transferred to the GBR lagoon. We have set up a multimedia chemical fate model for a tropical catchment to describe the fate of diuron within the Tully River catchment, Queensland, Australia. The model includes highly variable rainfall based on meteorological data from the Tully River catchment and a flood water compartment on top of the agricultural soil that is present during times for which floods were reported. The model is driven by diuron application data estimated for the Tully River catchment and is solved for time-dependent diuron concentrations in agricultural soil and seawater. Model results show that on average 25% of the diuron applied every year is transferred to the GBR lagoon with rainwater and flood water runoff. Diuron concentrations estimated for the seawater range from 0.1 ng/L to 12 ng/L and are in good agreement with concentrations measured in the GBR lagoon. The uncertainty of the diuron concentrations estimated for seawater is approximately a factor of two and mainly derives from uncertainty in the diuron degradation half-life in soil, properties of the soil compartment such as organic matter content, and the speed of the seawater current removing diuron dissolved in seawater from the seawater compartment of the model. Copyright © 2012 Elsevier B.V. All rights reserved.

A Herbivore Knows Its Patch: Luderick, Girella tricuspidata, Exhibit Strong Site Fidelity on Shallow Subtidal Reefs in a Temperate Marine Park

PubMed Central

Ferguson, Adrian M.; Harvey, Euan S.; Taylor, Matthew D.; Knott, Nathan A.

2013-01-01

Understanding movement patterns, habitat use and behaviour of fish is critical to determining how targeted species may respond to protection provided by “no-take” sanctuary zones within marine parks. We assessed the fine and broad scale movement patterns of an exploited herbivore, luderick (Girella tricuspidata), using acoustic telemetry to evaluate how this species may respond to protection within Jervis Bay (New South Wales, Australia). We surgically implanted fourteen fish with acoustic transmitters and actively and passively tracked individuals to determine fine and broad scale movement patterns respectively. Eight fish were actively tracked for 24 h d¯1 for 6 d (May 2011), and then intermittently over the following 30 d. Six fish were passively tracked from December 2011 to March 2012, using a fixed array of receivers deployed across rocky reefs around the perimeter of the bay. Luderick exhibited strong site fidelity on shallow subtidal reefs, tending to remain on or return consistently to the reef where they were caught and released. All eight fish actively tracked used core areas solely on their release reef, with the exception of one fish that used multiple core areas, and four of the six fish passively tracked spent between 75 to 96% of days on release reefs over the entire tracking period. Luderick did move frequently to adjacent reefs, and occasionally to more distant reefs, however consistently returned to their release reef. Luderick also exhibited predictable patterns in movement between spatially distinct daytime and night-time core use areas. Night-time core use areas were generally located in sheltered areas behind the edge of reefs. Overall, our data indicate luderick exhibit strong site fidelity on shallow subtidal reefs in Jervis Bay and suggests that this important herbivore may be likely to show a positive response to protection within the marine park. PMID:23741515

A herbivore knows its patch: luderick, Girella tricuspidata, exhibit strong site fidelity on shallow subtidal reefs in a temperate marine park.

PubMed

Ferguson, Adrian M; Harvey, Euan S; Taylor, Matthew D; Knott, Nathan A

2013-01-01

Understanding movement patterns, habitat use and behaviour of fish is critical to determining how targeted species may respond to protection provided by "no-take" sanctuary zones within marine parks. We assessed the fine and broad scale movement patterns of an exploited herbivore, luderick (Girella tricuspidata), using acoustic telemetry to evaluate how this species may respond to protection within Jervis Bay (New South Wales, Australia). We surgically implanted fourteen fish with acoustic transmitters and actively and passively tracked individuals to determine fine and broad scale movement patterns respectively. Eight fish were actively tracked for 24 h d¯(1) for 6 d (May 2011), and then intermittently over the following 30 d. Six fish were passively tracked from December 2011 to March 2012, using a fixed array of receivers deployed across rocky reefs around the perimeter of the bay. Luderick exhibited strong site fidelity on shallow subtidal reefs, tending to remain on or return consistently to the reef where they were caught and released. All eight fish actively tracked used core areas solely on their release reef, with the exception of one fish that used multiple core areas, and four of the six fish passively tracked spent between 75 to 96% of days on release reefs over the entire tracking period. Luderick did move frequently to adjacent reefs, and occasionally to more distant reefs, however consistently returned to their release reef. Luderick also exhibited predictable patterns in movement between spatially distinct daytime and night-time core use areas. Night-time core use areas were generally located in sheltered areas behind the edge of reefs. Overall, our data indicate luderick exhibit strong site fidelity on shallow subtidal reefs in Jervis Bay and suggests that this important herbivore may be likely to show a positive response to protection within the marine park.

Dietary partitioning by five sympatric species of stingray (Dasyatidae) on coral reefs.

PubMed

O'Shea, O R; Thums, M; van Keulen, M; Kempster, R M; Meekan, M G

2013-06-01

Dietary characteristics and the degree of dietary partitioning by five species of sympatric stingray were assessed using stomach content and sediment analyses within a coral reef lagoon at Ningaloo Reef, Western Australia (the cowtail Pastinachus atrus, blue-spotted fantail Taeniura lymma, blue-spotted mask Neotrygon kuhlii, porcupine Urogymnus asperrimus rays and the reticulate whipray Himantura uarnak). A total of 2804 items were recovered from the stomachs of 170 rays and 3215 individual taxa from the environment, which were used in selectivity analyses. Twenty-four prey taxa were identified from stomach contents and pooled into 10 taxonomic categories for analysis, of which annelids, prawns, brachyurans and bivalves were the most abundant, together accounting for 96% of the diet. Himantura uarnak had the greatest interspecific dissimilarity in diet, consuming a larger proportion of crustaceans, notably penaeids (41% of total diet) than the other four species of rays, all of which had diets dominated by annelids (71-82% of total diet). Crustacean specialization by H. uarnak may exist to maximize resources and reduce competition among sympatric species. The remaining species may partition resources on the basis of space, rather than diet. © 2013 The Authors. Journal of Fish Biology © 2013 The Fisheries Society of the British Isles.

Scale-invariance of sediment patterns - the fingerprint of fundamental drivers (Jean Baptiste Lamarck Medal Lecture)

NASA Astrophysics Data System (ADS)

Schlager, Wolfgang

2015-04-01

In contrast to the realms of magmatism and metamorphism, most depositional processes can be observed directly at the earth's surface. Observation of sediment patterns advanced significantly with the advent of remote sensing and 3D reflection seismics. Remote sensing is particularly relevant for the present topic because it documents mainly Holocene sediments - the best objects to link depositional processes to products. Classic examples of scale-invariant geometry are channel-fan systems, i.e. river-delta and canyon-fan complexes. The underlying control in both instances is the energy-dispersion of a channeled stream of water that discharges in a body of still water. The resulting fan-shaped sediment accumulations are scale-invariant over 7 orders of magnitude in linear size. The Mesozoic-Cenozoic record shows comparable trends and patterns. Further examples of depositional scale-invariance include foresets of non-cohesive sediments and braided-channel deposits. Reefs and carbonate platforms offer an example of scale-invariance related to biotic growth. Shallow-water carbonate platforms rimmed by reefs or reef-rimmed atolls with deep lagoons are characteristic morphologies of tropical carbonate deposits. The structure has been compared to a bucket where stiff reef rims hold a pile of loose sediment. Remote sensing data from the Maldive, Chagos and Laccadive archipelagos of the Indian Ocean show that bucket structures are the dominant depositional pattern from meter-size reefs to archipelagos of hundreds of kilometers in diameter, i.e. over more than 4 orders of magnitude in linear size. Over 2.5 orders of magnitude, the bucket structures qualify as statistical fractals. Ecologic and hydrodynamic studies on modern reefs suggest that the bucket structure is a form of biotic self-organization: The edge position in a reef is favored over the center position because bottom shear is higher and the diffusive boundary layer between reef and water thinner. Thus, the reef edge has easier access to nutrients. Moreover, the edge is less likely to be buried by sediment. The bucket structure is an ecologic response to these conditions. Buckets have been documented from all periods of the Phanerozoic and analogous structures from the late Proterozoic show that the microbial carbonate factory also built buckets. We conclude that a voyage through scales in the sediment realm reveals islands of scale-invariance wherever a single principle dominates the sedimentation process.

Effect of Inorganic and Organic Carbon Enrichments (DIC and DOC) on the Photosynthesis and Calcification Rates of Two Calcifying Green Algae from a Caribbean Reef Lagoon.

PubMed

Meyer, Friedrich W; Schubert, Nadine; Diele, Karen; Teichberg, Mirta; Wild, Christian; Enríquez, Susana

2016-01-01

Coral reefs worldwide are affected by increasing dissolved inorganic carbon (DIC) and organic carbon (DOC) concentrations due to ocean acidification (OA) and coastal eutrophication. These two stressors can occur simultaneously, particularly in near-shore reef environments with increasing anthropogenic pressure. However, experimental studies on how elevated DIC and DOC interact are scarce and fundamental to understanding potential synergistic effects and foreseeing future changes in coral reef function. Using an open mesocosm experiment, the present study investigated the impact of elevated DIC (pHNBS: 8.2 and 7.8; pCO2: 377 and 1076 μatm) and DOC (added as 833 μmol L-1 of glucose) on calcification and photosynthesis rates of two common calcifying green algae, Halimeda incrassata and Udotea flabellum, in a shallow reef environment. Our results revealed that under elevated DIC, algal photosynthesis decreased similarly for both species, but calcification was more affected in H. incrassata, which also showed carbonate dissolution rates. Elevated DOC reduced photosynthesis and calcification rates in H. incrassata, while in U. flabellum photosynthesis was unaffected and thalus calcification was severely impaired. The combined treatment showed an antagonistic effect of elevated DIC and DOC on the photosynthesis and calcification rates of H. incrassata, and an additive effect in U. flabellum. We conclude that the dominant sand dweller H. incrassata is more negatively affected by both DIC and DOC enrichments, but that their impact could be mitigated when they occur simultaneously. In contrast, U. flabellum can be less affected in coastal eutrophic waters by elevated DIC, but its contribution to reef carbonate sediment production could be further reduced. Accordingly, while the capacity of environmental eutrophication to exacerbate the impact of OA on algal-derived carbonate sand production seems to be species-specific, significant reductions can be expected under future OA scenarios, with important consequences for beach erosion and coastal sediment dynamics.

Effect of Inorganic and Organic Carbon Enrichments (DIC and DOC) on the Photosynthesis and Calcification Rates of Two Calcifying Green Algae from a Caribbean Reef Lagoon

PubMed Central

Diele, Karen; Teichberg, Mirta; Wild, Christian

2016-01-01

Coral reefs worldwide are affected by increasing dissolved inorganic carbon (DIC) and organic carbon (DOC) concentrations due to ocean acidification (OA) and coastal eutrophication. These two stressors can occur simultaneously, particularly in near-shore reef environments with increasing anthropogenic pressure. However, experimental studies on how elevated DIC and DOC interact are scarce and fundamental to understanding potential synergistic effects and foreseeing future changes in coral reef function. Using an open mesocosm experiment, the present study investigated the impact of elevated DIC (pHNBS: 8.2 and 7.8; pCO2: 377 and 1076 μatm) and DOC (added as 833 μmol L-1 of glucose) on calcification and photosynthesis rates of two common calcifying green algae, Halimeda incrassata and Udotea flabellum, in a shallow reef environment. Our results revealed that under elevated DIC, algal photosynthesis decreased similarly for both species, but calcification was more affected in H. incrassata, which also showed carbonate dissolution rates. Elevated DOC reduced photosynthesis and calcification rates in H. incrassata, while in U. flabellum photosynthesis was unaffected and thalus calcification was severely impaired. The combined treatment showed an antagonistic effect of elevated DIC and DOC on the photosynthesis and calcification rates of H. incrassata, and an additive effect in U. flabellum. We conclude that the dominant sand dweller H. incrassata is more negatively affected by both DIC and DOC enrichments, but that their impact could be mitigated when they occur simultaneously. In contrast, U. flabellum can be less affected in coastal eutrophic waters by elevated DIC, but its contribution to reef carbonate sediment production could be further reduced. Accordingly, while the capacity of environmental eutrophication to exacerbate the impact of OA on algal-derived carbonate sand production seems to be species-specific, significant reductions can be expected under future OA scenarios, with important consequences for beach erosion and coastal sediment dynamics. PMID:27487195

Coral ages and island subsidence, Hilo drill hole

USGS Publications Warehouse

Moore, J.G.; Ingram, B.L.; Ludwig, K. R.; Clague, D.A.

1996-01-01

A 25.8-m-thick sedimentary section containing coral fragments occurs directly below a surface lava flow (the ???1340 year old Panaewa lava flow) at the Hilo drill hole. Ten coral samples from this section dated by accelerator mass spectrometry (AMS) radiocarbon and five by thermal infrared multispectral scanner (TIMS) 230Th/U methods show good agreement. The calcareous unit is 9790 years old at the bottom and 1690 years old at the top and was deposited in a shallow lagoon behind an actively growing reef. This sedimentary unit is underlain by a 34-m-thick lava flow which in turn overlies a thin volcaniclastic silt with coral fragments that yield a single 14C date of 10,340 years. The age-depth relations of the dated samples can be compared with proposed eustatic sea level curves after allowance for island subsidence is taken. Island subsidence averages 2.2 mm/yr for the last 47 years based on measurements from a tide gage near the drill hole or 2.5-2.6 mm/yr for the last 500,000 years based on the ages and depths of a series of drowned coral reefs offshore from west Hawaii. The age-depth measurements of coral fragments are more consistent with eustatic sea levels as determined by coral dating at Barbados and Albrolhos Islands than those based on oxygen isotopic data from deep sea cores. The Panaewa lava flow entered a lagoon underlain by coral debris and covered the drill site with 30.9 m of lava of which 11 m was above sea level. This surface has now subsided to 4.2 m above sea level, but it demonstrates how a modern lava flow entering Hilo Bay would not only change the coastline but could extensively modify the offshore shelf.

Mapping Mesophotic Reefs Along the Brazilian Continental Margin

NASA Astrophysics Data System (ADS)

Bastos, A.; Moura, R.; Amado Filho, G.; Ferreira, L.; Boni, G.; Vedoato, F.; D'Agostini, D.; Lavagnino, A. C.; Leite, M. D.; Quaresma, V.

2017-12-01

Submerged or drowned reefs constitute an important geological record of sea level variations, forming the substrate for the colonization of modern benthic mesophotic communities. Although mapping mesophotic reefs has increased in the last years, their spatial distribution is poorly known and the worldwide occurrence of this reef habitat maybe underestimated. The importance in recognizing the distribution of mesophotic reefs is that they can act as a refuge for corals during unsuitable environmental conditions and a repository for shallow water corals. Here we present the result of several acoustic surveys that mapped and discovered new mesophotic reefs along the Eastern and Equatorial Brazilian Continental Margin. Seabed mapping was carried out using multibeam and side scan sonars. Ground truthing was obtained using drop camera or scuba diving. Mesophotic reefs were mapped in water depths varying from 30 to 100m and under distinct oceanographic conditions, especially in terms of river load input and shelf width. Reefs showed distinct morphologies, from low relief banks and paleovalleys to shelf edge ridges. Extensive occurrence of low relief banks were mapped along the most important coralline complex province in the South Atlantic, the Abrolhos Shelf. These 30 to 40m deep banks, have no more than 3 meters in height and may represent fringing reefs formed during sea level stabilization. Paleovalleys mapped along the eastern margin showed the occurrence of coralgal ledges along the channel margins. Paleovalleys are usually deeper than 45m and are associated with outer shelf rhodolith beds. Shelf edge ridges (80 to 120m deep) were mapped along both margins and are related to red algal encrusting irregular surfaces that have more than 3m in height, forming a rigid substrate for coral growth. Along the Equatorial Margin, off the Amazon mouth, shelf edge patch reefs and rhodolith beds forming encrusting surfaces and shelf edge ridges were mapped in water depths greater than 100m. Thus, the occurrence of mesophotic reefs along the Brazilian Margin is influenced by transgressive morphological features, which could be used as a surrogate for mesophotic reef distribution. The extensive occurrence of rhodolith beds on the outer shelf characterizes most of these reefs.

Earth Observations taken by the Expedition 10 crew

NASA Image and Video Library

2005-03-19

ISS010-E-20261 (19 March 2005) --- Jeddah, Saudi Arabia is featured in this image photographed by an Expedition 10 crewmember on the International Space Station. The city of Jeddah is the second largest city in Saudi Arabia (after Riyadh), and is the country’s most important Red Sea port. A large warehouse and dock complex is visible in the lower left portion of this image. Apart from being a major port for exchange of goods with Africa and Europe, Jeddah is of great importance for Islamic pilgrims going east to Mecca (a religious journey known as the hajj). In addition to urban attractions, coral reefs along the coast (north-south trending islands to image left) are frequented by divers visiting the city. The image captures the multicolored rooftops of homes and other buildings in the city, the oldest of which were built using coral from the nearby Red Sea and clay from the al-Manqabah lagoon in the center of the Al Balad district (center of image; lagoon is approximately 0.25 km across).

Water resources of the Truk Islands

USGS Publications Warehouse

Van der Brug, Otto

1983-01-01

The Truk Islands, part of the Caroline Islands in the western Pacific, consist of 19 volcanic islands and about 65 coral islets. The volcanic islands and some of the coral islets are scattered in an 820-square-mile lagoon enclosed by a 125-mile long barrier reef. Moen, although not the largest, is by far the most developed island and is the adminstrative, commercial, educational, and transporation center of the islands. Monthly rainfall records for most years are available since 1903. Rainfall-runoff comparisons show that about half the annual rainfall runs off as surface water into Truk Lagoon. Flow characteristics of the major streams, based on more than 11 years of record, are provided and the application of data for possible use in the design of reservoirs and rain catchments is included. Historical and present development of all water sources is given. The chemical analyses of surface and ground water on Moen, with the exception of water from well 9, show the good quality of the water sources. This report summarizes all hydrologic data collected and provides interpretations that can be used for development and management of the water resources. (USGS)

Book review of Littler DM. Littler MM (2000) Caribbean Reef Plants An Identification Guide to the Reef Plants of the Caribbean, Bahamas, Florida and Gulf of Mexico

NASA Astrophysics Data System (ADS)

Zuschin, M.; Hohenegger, J.; Steininger, F.

2001-09-01

Information on spatial variability and distribution patterns of organisms in coral reef environments is necessary to evaluate the increasing anthropogenic disturbance of marine environments (Richmond 1993; Wilkinson 1993; Dayton 1994). Therefore different types of subtidal, reef-associated hard substrata (reef flats, reef slopes, coral carpets, coral patches, rock grounds), each with different coral associations, were investigated to determine the distribution pattern of molluscs and their life habits (feeding strategies and substrate relations). The molluscs were strongly dominated by taxa with distinct relations to corals, and five assemblages were differentiated. The Dendropoma maxima assemblage on reef flats is a discrete entity, strongly dominated by this encrusting and suspension-feeding gastropod. All other assemblages are arranged along a substrate gradient of changing coral associations and potential molluscan habitats. The Coralliophila neritoidea- Barbatia foliata assemblage depends on the presence of Porites and shows a dominance of gastropods feeding on corals and of bivalves associated with living corals. The Chamoidea- Cerithium spp. assemblage on rock grounds is strongly dominated by encrusting bivalves. The Drupella cornus-Pteriidae assemblage occurs on Millepora- Acropora reef slopes and is strongly dominated by bivalves associated with living corals. The Barbatia setigera- Ctenoides annulata assemblage includes a broad variety of taxa, molluscan life habits and bottom types, but occurs mainly on faviid carpets and is transitional among the other three assemblages. A predicted degradation of coral coverage to rock bottoms due to increasing eutrophication and physical damage in the study area (Riegl and Piller 2000) will result in a loss of coral-associated molluscs in favor of bivalve crevice dwellers in dead coral heads and of encrusters on dead hard substrata.

Climate-driven variations in thermal forcing across a nearshore reef system during a marine heat wave and its potential impact on coral calcification

NASA Astrophysics Data System (ADS)

Falter, J.; Zhang, Z.; Lowe, R.; Foster, T.; McCulloch, M. T.

2016-02-01

We examined the oceanic and atmospheric forces driving seasonal and spatial variability in water temperature across backreef and lagoonal habitats at Coral Bay at Ningaloo Reef, Western Australia before, during, and after a historically unprecedented marine heat wave and resulting mass bleaching event in 2010-2011. Local deviations in the mean daily temperature of nearshore reef waters from offshore values were a linear function of the combined effect of net atmospheric heating and offshore wave height and period . While intra-annual variation in local heat exchange was driven mainly by seasonal changes in short-wave radiation; intra-annual variation in local cooling was driven mostly by changes in relative humidity (r2 = 0.60) and wind speed (r2 = 0.31) which exhibited no apparent seasonality. We demonstrate good agreement between nearshore reef temperatures modeled from offshore sea surface temperatures (SST), offshore wave forcing, and local atmospheric heat fluxes with observed temperatures using a simple linear model (r2 = 0.31 to 0.69, root-mean-square error = 0.4°C to 0.9°C). Using these modeled nearshore reef temperature records, we show that during the heat wave local thermal stresses across the reef reached as high as 18-34 °C-weeks and were being both intensified and accelerated by regional climate forcing when compared with offshore waters (12.6 °C-weeks max). Measurements of coral calcification made in Coral Bay following the bleaching event appear to lack any distinct seasonality; possibly due to the long-term effects of acute thermal stress. However, similarly minimal seasonality in calcification rates had also been observed in an Acropora-dominated community at Ningaloo years before the heat wave as well as more recently in coral from regions in WA that had avoided mass bleaching. These observations, in conjunction with observations that most of the bleached communities within Coral Bay had recovered their color within 3-6 months of the bleaching event, suggest that how reef building coral respond to a severe thermal stress event can be somewhat nuanced depending on the local and regional setting.

Modeling Hydrodynamics on the Wave Group Scale in Topographically Complex Reef Environments

NASA Astrophysics Data System (ADS)

Reyns, J.; Becker, J. M.; Merrifield, M. A.; Roelvink, J. A.

2016-02-01

The knowledge of the characteristics of waves and the associated wave-driven currents is important for sediment transport and morphodynamics, nutrient dynamics and larval dispersion within coral reef ecosystems. Reef-lined coasts differ from sandy beaches in that they have a steep offshore slope, that the non-sandy bottom topography is very rough, and that the distance between the point of maximum short wave dissipation and the actual coastline is usually large. At this short wave breakpoint, long waves are released, and these infragravity (IG) scale motions account for the bulk of the water level variance on the reef flat, the lagoon and eventually, the sandy beaches fronting the coast through run-up. These IG energy dominated water level motions are reinforced during extreme events such as cyclones or swells through larger incident band wave heights and low frequency wave resonance on the reef. Recently, a number of hydro(-morpho)dynamic models that have the capability to model these IG waves have successfully been applied to morphologically differing reef environments. One of these models is the XBeach model, which is curvilinear in nature. This poses serious problems when trying to model an entire atoll for example, as it is extremely difficult to build curvilinear grids that are optimal for the simulation of hydrodynamic processes, while maintaining the topology in the grid. One solution to remediate this problem of grid connectivity is the use of unstructured grids. We present an implementation of the wave action balance on the wave group scale with feedback to the flow momentum balance, which is the foundation of XBeach, within the framework of the unstructured Delft3D Flexible Mesh model. The model can be run in stationary as well as in instationary mode, and it can be forced by regular waves, time series or wave spectra. We show how the code is capable of modeling the wave generated flow at a number of topographically complex reef sites and for a number of different forcing conditions, by comparison with field data.

Ocean Acidification Refugia of the Florida Reef Tract

NASA Astrophysics Data System (ADS)

Manzello, D.; Enochs, I.; Melo, N.; Gledhill, D. K.; Johns, E. M.

2012-12-01

Ocean acidification (OA) is expected to reduce the calcification rates of marine organisms, yet we have little understanding of how OA will manifest within dynamic, real-world systems. Natural CO2, alkalinity, and salinity gradients can significantly alter local carbonate chemistry, and thereby create a range of susceptibility for different ecosystems to OA. As such, there is a need to characterize this natural variability of seawater carbonate chemistry, especially within coastal ecosystems. Since 2009, carbonate chemistry data have been collected on the Florida Reef Tract (FRT). During periods of heightened productivity, there is a net uptake of total CO2 (TCO2) which increases aragonite saturation state (Ωarag) values on inshore patch reefs of the upper FRT. These waters can exhibit greater Ωarag than what has been modeled for the tropical surface ocean during preindustrial times, with mean (± std. error) Ωarag-values in spring = 4.69 (± 0.101). Conversely, Ωarag-values on offshore reefs generally represent oceanic carbonate chemistries consistent with present day tropical surface ocean conditions. This gradient is opposite from what has been reported for other reef environments. We hypothesize this pattern is caused by the photosynthetic uptake of TCO2 mainly by seagrasses and, to a lesser extent, macroalgae in the inshore waters of the FRT. These inshore reef habitats are therefore potential acidification refugia that are defined not only in a spatial sense, but also in time; coinciding with seasonal productivity dynamics. Coral reefs located within or immediately downstream of seagrass beds may find refuge from OA.

Ocean Acidification Refugia of the Florida Reef Tract

PubMed Central

Manzello, Derek P.; Enochs, Ian C.; Melo, Nelson; Gledhill, Dwight K.; Johns, Elizabeth M.

2012-01-01

Ocean acidification (OA) is expected to reduce the calcification rates of marine organisms, yet we have little understanding of how OA will manifest within dynamic, real-world systems. Natural CO2, alkalinity, and salinity gradients can significantly alter local carbonate chemistry, and thereby create a range of susceptibility for different ecosystems to OA. As such, there is a need to characterize this natural variability of seawater carbonate chemistry, especially within coastal ecosystems. Since 2009, carbonate chemistry data have been collected on the Florida Reef Tract (FRT). During periods of heightened productivity, there is a net uptake of total CO2 (TCO2) which increases aragonite saturation state (Ωarag) values on inshore patch reefs of the upper FRT. These waters can exhibit greater Ωarag than what has been modeled for the tropical surface ocean during preindustrial times, with mean (± std. error) Ωarag-values in spring = 4.69 (±0.101). Conversely, Ωarag-values on offshore reefs generally represent oceanic carbonate chemistries consistent with present day tropical surface ocean conditions. This gradient is opposite from what has been reported for other reef environments. We hypothesize this pattern is caused by the photosynthetic uptake of TCO2 mainly by seagrasses and, to a lesser extent, macroalgae in the inshore waters of the FRT. These inshore reef habitats are therefore potential acidification refugia that are defined not only in a spatial sense, but also in time; coinciding with seasonal productivity dynamics. Coral reefs located within or immediately downstream of seagrass beds may find refuge from OA. PMID:22848575

Ocean acidification refugia of the Florida Reef Tract.

PubMed

Manzello, Derek P; Enochs, Ian C; Melo, Nelson; Gledhill, Dwight K; Johns, Elizabeth M

2012-01-01

Ocean acidification (OA) is expected to reduce the calcification rates of marine organisms, yet we have little understanding of how OA will manifest within dynamic, real-world systems. Natural CO(2), alkalinity, and salinity gradients can significantly alter local carbonate chemistry, and thereby create a range of susceptibility for different ecosystems to OA. As such, there is a need to characterize this natural variability of seawater carbonate chemistry, especially within coastal ecosystems. Since 2009, carbonate chemistry data have been collected on the Florida Reef Tract (FRT). During periods of heightened productivity, there is a net uptake of total CO(2) (TCO(2)) which increases aragonite saturation state (Ω(arag)) values on inshore patch reefs of the upper FRT. These waters can exhibit greater Ω(arag) than what has been modeled for the tropical surface ocean during preindustrial times, with mean (± std. error) Ω(arag)-values in spring = 4.69 (±0.101). Conversely, Ω(arag)-values on offshore reefs generally represent oceanic carbonate chemistries consistent with present day tropical surface ocean conditions. This gradient is opposite from what has been reported for other reef environments. We hypothesize this pattern is caused by the photosynthetic uptake of TCO(2) mainly by seagrasses and, to a lesser extent, macroalgae in the inshore waters of the FRT. These inshore reef habitats are therefore potential acidification refugia that are defined not only in a spatial sense, but also in time; coinciding with seasonal productivity dynamics. Coral reefs located within or immediately downstream of seagrass beds may find refuge from OA.

The Açu Reef morphology, distribution, and inter reef sedimentation on the outer shelf of the NE Brazil equatorial margin

NASA Astrophysics Data System (ADS)

do Nascimento Silva, Luzia Liniane; Gomes, Moab Praxedes; Vital, Helenice

2018-05-01

Submerged reefs, referred to as the Açu Reefs, have been newly observed on both sides of the Açu Incised Valley on the northeastern equatorial Brazilian outer shelf. This study aims to understand the roles of shelf physiography, its antecedent morphologies, and its inter reef sedimentation on the different development stages of the biogenic reef during last deglacial sea-level rise. The data sets consist of side-scan sonar imagery, one sparker seismic profile, 76 sediment samples, and underwater photography. Seven backscatter patterns (P1 to P7) were identified and associated with eleven sedimentary carbonate and siliciclastic facies. The inherited relief, the mouth of the paleo incised valley, and the interreef sediment distribution play major controls on the deglacial reef evolution. The reefs occur in a depth-limited 25-55 m water depth range and in a 6 km wide narrow zone of the outer shelf. The reefs crop out in a surface area over 100 km2 and occur as a series of NW-SE preferentially orientated ridges composed of three parallel ridge sets at 45, 35, and 25 m of water depth. The reefs form a series of individual, roughly linear ridges, tens of km in length, acting as barriers in addition to scattered reef mounds or knolls, averaging 4 m in height and grouped in small patches and aggregates. The reefs, currently limited at the transition between the photic and mesophotic zones, are thinly covered by red algae and scattered coral heads and sponges. Taking into account the established sea-level curves from the equatorial Brazilian northeastern shelf / Rochas Atoll and Barbados, the shelf physiography, and the shallow bedrock, the optimal conditions for reef development had to occur during a time interval (11-9 kyr BP) characterized by a slowdown of the outer shelf flooding, immediately following Meltwater Pulse-1B. This 2 kyr short interval provided unique conditions for remarkable reef backstepping into distinct parallel ridge sets. Furthermore, the Açu Reefs have trapped relict siliciclastic sediments within the three sets of reefs, west of the Açu Incised Valley and adjacent coasts. Lines evidence of easterly nearshore currents carried sediments from the old Açu Incised Valley and adjacent coasts. These incipiently drowned reefs influence the water circulation patterns of the modern shelf system, its carbonate sedimentation, and sediment transport. This study provides a new example of reef occurrence which might be more commonly observed on similar equatorial continental shelves.

Quantity, structure, and habitat selection of natural spawning reefs by walleyes in a north temperate lake: A multiscale analysis

USGS Publications Warehouse

Raabe, Joshua K.; Bozek, Michael A.

2012-01-01

Spawning habitat, the cornerstone of self-sustaining, naturally reproducing walleyeSander vitreus populations, has received limited quantitative research. Our goal was to quantitatively describe the structure and quantity of natural walleye spawning habitat and evaluate potential selection of habitat in Big Crooked Lake, Wisconsin. In 2004 and 2005, we located and delineated walleye egg deposition polygons through visual snorkel and scuba surveys. We also delineated recently deposited, adhesive egg patches daily along one spawning reef in 2005. To determine habitat selection, we quantified and compared spawning and lakewide available habitat at different scales. In both years, walleyes used similar spawning habitat, including three geomorphic types: linear shorelines, a point bar, and an island. Walleyes used only 14% of the entire lake shoreline and 39% of the shoreline comprised of gravel (6.4–76.0 mm), cobble (76.1–149.9 mm), or coarser substrates for spawning in 2005, indicating selection of specific spawning habitat. Lakewide, walleyes spawned close to shore (outer egg deposition polygon boundary mean distance = 2.7 m), in shallow water (outer egg deposition polygon boundary mean depth = 0.3 m), and over gravel substrate (percent coverage mean = 64.3) having low embeddedness (mean = 1.30). Our best nearshore (0–13-m) resource selection function predicted an increase in the relative probability of egg deposition with the increasing abundance of gravel, cobble, and rubble (150.0–303.9-mm) substrates and a decrease with increasing distance from shore and water depth (89.9% overall correct classification). Adhesive egg patches confirmed that walleyes actively chose nearshore, shallow-water, and coarse-substrate spawning habitat. The quantitative habitat information and predictive models will assist biologists in developing walleye spawning reef protection strategies and potentially aid in designing and evaluating artificial spawning reefs.

Petrography, diagenesis, and reservoir properties of Miocene Reefs, Visayan Islands, Philippines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Carozzi, A.V.

1988-01-01

The Miocene reefs of the volcanic island arcs making up the Visayan Islands, Philippines, consist of an association of corals, red algae, bryozoans, and encrusting foraminifers forming barriers along the edge of narrow shelves. Bioclasts and intraclasts derived from these wave-resistant barriers were shed as frontal aprons of calcirudites and calcarenites that sometimes support pinnacle coralling buildups. These aprons were intersected by tidal-channel calcarenites grading seaward into carbonate turbidite submarine fans that interfingered with deep-water pelagic argillaceous micrites and shales. Lagoons with low energy micritic and pelletoidal muds. although intersected by numerous well-sorted tidal channel calcarenites, displayed an ecologically zonedmore » succession of small buildups that, in a landward direction, were: (1) finger-coral constructed; (2) larger, benthic foraminifer bioaccumulated; (3) small arenaceous foraminifer, gastropod, and red algae bioaccumulated. The shoreface environment consisted of mixed carbonates and andesitic grkaywackes grading landward into mangrove tidal flats and estuaries. Reservoirs were mainly developed in constructed barriers and in immediately adjacent frontal aprons and rear bioclastic carbonates. Many of these high-energy carbonates show interstitial micritic matrix. Porosity (reaching 30%) and permeability (reaching 146 md) result from a locally variable combination of the effects of subaerial exposure introducing secondary porosity by vadose to upper phreatic undersaturated dissolution,followed by extensive burial dissolution. Seals are provided between superposed barriers by andesitic volcaniclastics and basaltic flows. Uplifted Pleistocene reefs of Barbados, West Indies, which are nearly identical to Holocene West Indian reefs are excellent analogs of the Miocene examples except for the lack of active volcanism.« less

Power analysis as a tool to identify statistically informative indicators for monitoring coral reef disturbances.

PubMed

Van Wynsberge, Simon; Gilbert, Antoine; Guillemot, Nicolas; Heintz, Tom; Tremblay-Boyer, Laura

2017-07-01

Extensive biological field surveys are costly and time consuming. To optimize sampling and ensure regular monitoring on the long term, identifying informative indicators of anthropogenic disturbances is a priority. In this study, we used 1800 candidate indicators by combining metrics measured from coral, fish, and macro-invertebrate assemblages surveyed from 2006 to 2012 in the vicinity of an ongoing mining project in the Voh-Koné-Pouembout lagoon, New Caledonia. We performed a power analysis to identify a subset of indicators which would best discriminate temporal changes due to a simulated chronic anthropogenic impact. Only 4% of tested indicators were likely to detect a 10% annual decrease of values with sufficient power (>0.80). Corals generally exerted higher statistical power than macro-invertebrates and fishes because of lower natural variability and higher occurrence. For the same reasons, higher taxonomic ranks provided higher power than lower taxonomic ranks. Nevertheless, a number of families of common sedentary or sessile macro-invertebrates and fishes also performed well in detecting changes: Echinometridae, Isognomidae, Muricidae, Tridacninae, Arcidae, and Turbinidae for macro-invertebrates and Pomacentridae, Labridae, and Chaetodontidae for fishes. Interestingly, these families did not provide high power in all geomorphological strata, suggesting that the ability of indicators in detecting anthropogenic impacts was closely linked to reef geomorphology. This study provides a first operational step toward identifying statistically relevant indicators of anthropogenic disturbances in New Caledonia's coral reefs, which can be useful in similar tropical reef ecosystems where little information is available regarding the responses of ecological indicators to anthropogenic disturbances.

Seagrass habitat complexity and macroinvertebrate abundance in Lakshadweep coral reef lagoons, Arabian Sea

NASA Astrophysics Data System (ADS)

Ansari, Z. A.; Rivonker, C. U.; Ramani, P.; Parulekar, A. H.

1991-09-01

Macrofauna of seagrass community in the five Lakshadweep atolls were studied and compared. The associated epifaunal and infaunal taxa comprising nine major taxonomic groups, showed significant differences in the total number of individuals (1041 8411 m-2) among sites and habitats. The density of macrofauna was directly related to mean macrophytic biomass (405 895 g wet wt. m-2). The fauna was dominated by epifaunal polychaetes, amphipods and isopods in the vegetated areas. When compared with the density of nearby unvegetated areasleft( {bar x = 815{text{m }}^{ - 2} } right), seagrass meadows harbour a denser and richer macroinvertebrate assemblageleft( {bar x = 4023{text{m }}^{ - 2} } right).

Holocene evolution of Dahab coastline - Gulf of Aqaba, Sinai Peninsula, Egypt

NASA Astrophysics Data System (ADS)

Magdy, Torab

2016-04-01

Dahab was a little Bedouin-village in Sinai Peninsula at the mid-western coast of Gulf of Aqaba approx. 90 km north of Sharm-el-Sheikh City and it means "gold" in Arabic language. But in the past 20 years ago it becomes one of the most tourist sites in Egypt. The basement complex is composed mostly of biotiteaplite-granite, mica-aplitegranite, granodiorite, quartzdiorite, alaskite, and diorite. Based on correlation with similar igneous in the most southern part of Sinai and the Red Sea area. Wadi Dahab composed of igneous and metamorphic rocks and the coastline is formed of the fragments of its rocks, mixed with fragments of coral reef and fluvial deposits of Wadi Dahab. The morphology of Dahab coastline is characterized by hooked marine spit, which composed of fluvial sediments carried by marine current from wadi Dahab mouth, this spit encloses shallow lagoon, but the active deposition on the lagoon bottom will evaluate it into saline marsh. This paper dealing with the evolution of Dahab spit and lagoon during the Holocene in addition to the recent time for last 100 years, and it impacts of the future management of the coast area. The coastline mapping during the period of study depends upon GIS technique for data were collected during field measuring by using total station, aerial photo and satellite image interpretation as well as soil sample dating. Suggested geomorphological evolution of Dahab area during the Holocene depending upon geomorphic investigation of the sedimentological process into 6 stages.

Diurnal warming in shallow coastal seas: Observations from the Caribbean and Great Barrier Reef regions

NASA Astrophysics Data System (ADS)

Zhu, X.; Minnett, P. J.; Berkelmans, R.; Hendee, J.; Manfrino, C.

2014-07-01

A good understanding of diurnal warming in the upper ocean is important for the validation of satellite-derived sea surface temperature (SST) against in-situ buoy data and for merging satellite SSTs taken at different times of the same day. For shallow coastal regions, better understanding of diurnal heating could also help improve monitoring and prediction of ecosystem health, such as coral reef bleaching. Compared to its open ocean counterpart which has been studied extensively and modeled with good success, coastal diurnal warming has complicating localized characteristics, including coastline geometry, bathymetry, water types, tidal and wave mixing. Our goal is to characterize coastal diurnal warming using two extensive in-situ temperature and weather datasets from the Caribbean and Great Barrier Reef (GBR), Australia. Results showed clear daily warming patterns in most stations from both datasets. For the three Caribbean stations where solar radiation is the main cause of daily warming, the mean diurnal warming amplitudes were about 0.4 K at depths of 4-7 m and 0.6-0.7 K at shallower depths of 1-2 m; the largest warming value was 2.1 K. For coral top temperatures of the GBR, 20% of days had warming amplitudes >1 K, with the largest >4 K. The bottom warming at shallower sites has higher daily maximum temperatures and lower daily minimum temperatures than deeper sites nearby. The averaged daily warming amplitudes were shown to be closely related to daily average wind speed and maximum insolation, as found in the open ocean. Diurnal heating also depends on local features including water depth, location on different sections of the reef (reef flat vs. reef slope), the relative distance from the barrier reef chain (coast vs. lagoon stations vs. inner barrier reef sites vs. outer rim sites); and the proximity to the tidal inlets. In addition, the influence of tides on daily temperature changes and its relative importance compared to solar radiation was quantified by calculating the ratio of power spectrum densities at the principal lunar semidiurnal M2 tide versus 24-hour cycle frequency representing mainly solar radiation forcing, i.e., (PSDM2/PSD24). Despite the fact that GBR stations are generally located at regions with large tidal changes, the tidal effects were modest: 80% of stations showed value of (PSDM2/PSD24) of less than 10%.

The use of remote sensing and linear wave theory to model local wave energy around Alphonse Atoll, Seychelles

NASA Astrophysics Data System (ADS)

Hamylton, S.

2011-12-01

This paper demonstrates a practical step-wise method for modelling wave energy at the landscape scale using GIS and remote sensing techniques at Alphonse Atoll, Seychelles. Inputs are a map of the benthic surface (seabed) cover, a detailed bathymetric model derived from remotely sensed Compact Airborne Spectrographic Imager (CASI) data and information on regional wave heights. Incident energy at the reef crest around the atoll perimeter is calculated as a function of its deepwater value with wave parameters (significant wave height and period) hindcast in the offshore zone using the WaveWatch III application developed by the National Oceanographic and Atmospheric Administration. Energy modifications are calculated at constant intervals as waves transform over the forereef platform along a series of reef profile transects running into the atoll centre. Factors for shoaling, refraction and frictional attenuation are calculated at each interval for given changes in bathymetry and benthic coverage type and a nominal reduction in absolute energy is incorporated at the reef crest to account for wave breaking. Overall energy estimates are derived for a period of 5 years and related to spatial patterning of reef flat surface cover (sand and seagrass patches).

First description of a Lophelia pertusa reef complex in Atlantic Canada

NASA Astrophysics Data System (ADS)

Buhl-Mortensen, Pål; Gordon, Don C.; Buhl-Mortensen, Lene; Kulka, Dave W.

2017-08-01

For the first time, we describe a cold-water coral reef complex in Atlantic Canada, discovered at the shelf break, in the mouth of the Laurentian Channel. The study is based on underwater video and sidescan sonar. The reef complex covered an area of approximately 490×1300 m, at 280-400 m depth. It consisted of several small mounds (< 3 m high) where the scleractinian Lophelia pertusa occurred as live colonies, dead blocks and skeletal rubble. On the mounds, a total of 67 live colonies occurred within 14 patches at 300-320 m depth. Most of these (67%) were small (< 20 cm high). Dead coral (rubble and blocks), dominated (88% of all coral observations). Extensive signs of damage by bottom-fishing gear were observed: broken and tilted coral colonies, over-turned boulders and lost fishing gear. Fisheries observer data indicated that the reef complex was subjected to heavy otter trawling annually between 1980 and 2000. In June 2004, a 15 km2 conservation area excluding all bottom-fishing was established. Current bottom fisheries outside the closure include otter trawling for redfish and anchored longlines for halibut. Vessel monitoring system data indicate that the closure is generally respected by the fishing industry.

Environmental contamination associated with a marine landfill ('seafill') beside a coral reef.

PubMed

Jones, Ross

2010-11-01

In Bermuda, bulk waste such as scrap metal, cars, etc., and blocks of cement-stabilized incinerator ash (produced from burning garbage) are disposed of in a foreshore reclamation site, i.e., a seafill. Chemical analyses show that seawater leaching out of the dump regularly exceeds water quality guidelines for Zn and Cu, and that the surrounding sediments are enriched in multiple contaminant classes (metals, polycyclic aromatic hydrocarbons, petroleum hydrocarbons, dioxins and furans, polychlorinated biphenyls and an organochlorine pesticide), i.e., there is a halo of contamination. When compared against biological effects-based sediment quality guidelines (SQGs), numerous sediment samples exceeded the low-range values (where biological effects become possible), and for Hg and Zn exceeded the mid-range value (where they become probable). A few metres away from the edge of the 25 acre dump lies a small coral patch reef, proposed here as most contaminated coral reef in the world. Copyright © 2010 Elsevier Ltd. All rights reserved.

Characterizing Manatee habitat use and seagrass grazing in Florida and Puerto Rico: Implications for conservation and management

USGS Publications Warehouse

Lefebvre, L.W.; Reid, J.P.; Kenworthy, W.J.; Powell, J.A.

2000-01-01

The Indian River Lagoon on the Atlantic coast of Florida, USA, and the east coast of Puerto Rico provide contrasting environments in which the endangered West Indian Manatee Trichechus manatus experiences different thermal regimes and seagrass communities. We compare Manatee feeding behaviour in these two regions, examine the ecological effects of Manatee grazing on a seagrass community in the Indian River Lagoon, describe the utility of aerial surveys, radio tracking, and seagrass mapping to study Manatee feeding patterns, and develop hypotheses on sirenian feeding strategies in temperate and tropical seagrass communities. In both the Indian River Lagoon and Puerto Rico, Manatees were typically observed grazing in water depths = 2.0 m and more frequently on the most abundant seagrasses present in the community: Halodule wrightii in the Indian River Lagoon and Thalassia testudinum in eastern Puerto Rico. Where both H. wrightii and Syringodium filiforme were consumed in the Indian River Lagoon, Manatees tended to remove more S. filiforme than H. wrightii rhizome + root biomass. Even though 80 to 95% of the short-shoot biomass and 50 to 67% of the rhizome + root biomass were removed, grazed patches of H. wrightii and S. filiforme recovered significantly between February and August. H. wrightii may be both more resistant and resilient than S. filiforme to the impacts of Manatee grazing. Despite the significantly greater abundance of T. testudinum in Puerto Rico, Manatees exhibited selective feeding by returning to specific sites with abundant H. wrightii. They also appeared to feed selectively on T. testudinum shoots associated with clumps of the calcareous alga Halimeda opuntia. We hypothesize that Florida Manatees are less specialized seagrass grazers than Manatees in tropical regions like Puerto Rico. Continued research on Manatee grazing ecology in temperate to tropical seagrass communities will enable better protection and management of these vital and unique marine resources.

A 1500-year holocene caribbean climate archive from the Blue Hole, lighthouse reef, belize

USGS Publications Warehouse

Gischler, E.; Shinn, E.A.; Oschmann, W.; Fiebig, J.; Buster, N.A.

2008-01-01

Sediment cores (up to 6 m in length) from the bottom of the Blue Hole, a 125 m deep Pleistocene sinkhole located in the lagoon of Lighthouse Reef Atoll, Belize, consist of undisturbed, annually layered biogenic carbonate muds and silts with intercalated coarser grained storm beds. The sedimentation rate of the layered sections is 2.5 mm/y on average, and the long cores span the past 1500 years. Oxygen isotopes of laminated sediment provide a late Holocene climate proxy: A high-resolution ??18O time series traces the final Migration Period Pessimum, the Medieval Warm Period, the Little Ice Age, and the subsequent temperature rise. Carbon isotopes (??13C) decrease up core and show the impacts of the decline of the Mayan culture and the Suess effect. Time series analyses of ??18O and ??13C content reveal 88-, 60-, 52-, and 32-year cyclicities, and suggest solar forcing. Storm event beds are most common during AD 650-850, around AD 1000, during AD 1200-1300, and AD 1450-1550. Major storm beds are rare during the past 500 years BP.

Investigating Bermuda's pollution history through stable isotope analyses of modern and museum-held gorgonian corals.

PubMed

Baker, David M; Murdoch, Thaddeus J T; Conti-Jerpe, Inga; Fogel, Marilyn

2017-01-15

For centuries, Bermuda has been challenged with wastewater management for the protection of human and environmental health. By quantifying the δ 15 N of the common sea fan Gorgonia ventalina sampled from 30 sites throughout Bermuda we show that sewage-derived nitrogen is detectable on nearshore coral reefs and declines across the lagoon to the outer rim. We also sampled gorgonians from two museum collections representing a 50y time-series (1958-2008). These samples revealed an increase in δ 15 N of >4.0‰ until the mid-1970s, after which δ 15 N values slowly declined by ~2.0‰. A δ 15 N chronology from a gorgonian skeleton exhibited a similar decline over the last 30-40years of approximately 0.6‰. We conclude that policies have been effective in reducing sewage impacts to Bermudian reefs. However, significant sources of sewage pollution persist and are likely have a strong impact on harbor and nearshore coral communities and human health. Copyright © 2016 Elsevier Ltd. All rights reserved.

Depth as an Organizing Force in Pocillopora damicornis: Intra-Reef Genetic Architecture

PubMed Central

Gorospe, Kelvin D.; Karl, Stephen A.

2015-01-01

Relative to terrestrial plants, and despite similarities in life history characteristics, the potential for corals to exhibit intra-reef local adaptation in the form of genetic differentiation along an environmental gradient has received little attention. The potential for natural selection to act on such small scales is likely increased by the ability of coral larval dispersal and settlement to be influenced by environmental cues. Here, we combine genetic, spatial, and environmental data for a single patch reef in Kāne‘ohe Bay, O‘ahu, Hawai‘i, USA in a landscape genetics framework to uncover environmental drivers of intra-reef genetic structuring. The genetic dataset consists of near-exhaustive sampling (n = 2352) of the coral, Pocillopora damicornis at our study site and six microsatellite genotypes. In addition, three environmental parameters – depth and two depth-independent temperature indices – were collected on a 4 m grid across 85 locations throughout the reef. We use ordinary kriging to spatially interpolate our environmental data and estimate the three environmental parameters for each colony. Partial Mantel tests indicate a significant correlation between genetic relatedness and depth while controlling for space. These results are also supported by multi-model inference. Furthermore, spatial Principle Component Analysis indicates a statistically significant genetic cline along a depth gradient. Binning the genetic dataset based on size-class revealed that the correlation between genetic relatedness and depth was significant for new recruits and increased for larger size classes, suggesting a possible role of larval habitat selection as well as selective mortality in structuring intra-reef genetic diversity. That both pre- and post-recruitment processes may be involved points to the adaptive role of larval habitat selection in increasing adult survival. The conservation importance of uncovering intra-reef patterns of genetic diversity is discussed. PMID:25806798

Molluscan assemblages on coral reefs and associated hard substrata in the northern Red Sea

NASA Astrophysics Data System (ADS)

Zuschin, M.; Hohenegger, J.; Steininger, F.

2001-09-01

Information on spatial variability and distribution patterns of organisms in coral reef environments is necessary to evaluate the increasing anthropogenic disturbance of marine environments (Richmond 1993; Wilkinson 1993; Dayton 1994). Therefore different types of subtidal, reef-associated hard substrata (reef flats, reef slopes, coral carpets, coral patches, rock grounds), each with different coral associations, were investigated to determine the distribution pattern of molluscs and their life habits (feeding strategies and substrate relations). The molluscs were strongly dominated by taxa with distinct relations to corals, and five assemblages were differentiated. The Dendropoma maxima assemblage on reef flats is a discrete entity, strongly dominated by this encrusting and suspension-feeding gastropod. All other assemblages are arranged along a substrate gradient of changing coral associations and potential molluscan habitats. The Coralliophila neritoidea- Barbatia foliata assemblage depends on the presence of Porites and shows a dominance of gastropods feeding on corals and of bivalves associated with living corals. The Chamoidea- Cerithium spp. assemblage on rock grounds is strongly dominated by encrusting bivalves. The Drupella cornus-Pteriidae assemblage occurs on Millepora- Acropora reef slopes and is strongly dominated by bivalves associated with living corals. The Barbatia setigera- Ctenoides annulata assemblage includes a broad variety of taxa, molluscan life habits and bottom types, but occurs mainly on faviid carpets and is transitional among the other three assemblages. A predicted degradation of coral coverage to rock bottoms due to increasing eutrophication and physical damage in the study area (Riegl and Piller 2000) will result in a loss of coral-associated molluscs in favor of bivalve crevice dwellers in dead coral heads and of encrusters on dead hard substrata.

Future reef decalcification under a business-as-usual CO2 emission scenario

PubMed Central

Dove, Sophie G.; Kline, David I.; Pantos, Olga; Angly, Florent E.; Tyson, Gene W.; Hoegh-Guldberg, Ove

2013-01-01

Increasing atmospheric partial pressure of CO2 (pCO2) is a major threat to coral reefs, but some argue that the threat is mitigated by factors such as the variability in the response of coral calcification to acidification, differences in bleaching susceptibility, and the potential for rapid adaptation to anthropogenic warming. However the evidence for these mitigating factors tends to involve experimental studies on corals, as opposed to coral reefs, and rarely includes the influence of multiple variables (e.g., temperature and acidification) within regimes that include diurnal and seasonal variability. Here, we demonstrate that the inclusion of all these factors results in the decalcification of patch-reefs under business-as-usual scenarios and reduced, although positive, calcification under reduced-emission scenarios. Primary productivity was found to remain constant across all scenarios, despite significant bleaching and coral mortality under both future scenarios. Daylight calcification decreased and nocturnal decalcification increased sharply from the preindustrial and control conditions to the future scenarios of low (reduced emissions) and high (business-as-usual) increases in pCO2. These changes coincided with deeply negative carbonate budgets, a shift toward smaller carbonate sediments, and an increase in the abundance of sediment microbes under the business-as-usual emission scenario. Experimental coral reefs demonstrated highest net calcification rates and lowest rates of coral mortality under preindustrial conditions, suggesting that reef processes may not have been able to keep pace with the relatively minor environmental changes that have occurred during the last century. Taken together, our results have serious implications for the future of coral reefs under business-as-usual environmental changes projected for the coming decades and century. PMID:24003127

Archaeal and Bacterial Communities Associated with the Surface Mucus of Caribbean Corals Differ in Their Degree of Host Specificity and Community Turnover Over Reefs.

PubMed

Frade, Pedro R; Roll, Katharina; Bergauer, Kristin; Herndl, Gerhard J

2016-01-01

Comparative studies on the distribution of archaeal versus bacterial communities associated with the surface mucus layer of corals have rarely taken place. It has therefore remained enigmatic whether mucus-associated archaeal and bacterial communities exhibit a similar specificity towards coral hosts and whether they vary in the same fashion over spatial gradients and between reef locations. We used microbial community profiling (terminal-restriction fragment length polymorphism, T-RFLP) and clone library sequencing of the 16S rRNA gene to compare the diversity and community structure of dominant archaeal and bacterial communities associating with the mucus of three common reef-building coral species (Porites astreoides, Siderastrea siderea and Orbicella annularis) over different spatial scales on a Caribbean fringing reef. Sampling locations included three reef sites, three reef patches within each site and two depths. Reference sediment samples and ambient water were also taken for each of the 18 sampling locations resulting in a total of 239 samples. While only 41% of the bacterial operational taxonomic units (OTUs) characterized by T-RFLP were shared between mucus and the ambient water or sediment, for archaeal OTUs this percentage was 2-fold higher (78%). About half of the mucus-associated OTUs (44% and 58% of bacterial and archaeal OTUs, respectively) were shared between the three coral species. Our multivariate statistical analysis (ANOSIM, PERMANOVA and CCA) showed that while the bacterial community composition was determined by habitat (mucus, sediment or seawater), host coral species, location and spatial distance, the archaeal community composition was solely determined by the habitat. This study highlights that mucus-associated archaeal and bacterial communities differ in their degree of community turnover over reefs and in their host-specificity.

Future reef decalcification under a business-as-usual CO2 emission scenario.

PubMed

Dove, Sophie G; Kline, David I; Pantos, Olga; Angly, Florent E; Tyson, Gene W; Hoegh-Guldberg, Ove

2013-09-17

Increasing atmospheric partial pressure of CO2 (pCO2) is a major threat to coral reefs, but some argue that the threat is mitigated by factors such as the variability in the response of coral calcification to acidification, differences in bleaching susceptibility, and the potential for rapid adaptation to anthropogenic warming. However the evidence for these mitigating factors tends to involve experimental studies on corals, as opposed to coral reefs, and rarely includes the influence of multiple variables (e.g., temperature and acidification) within regimes that include diurnal and seasonal variability. Here, we demonstrate that the inclusion of all these factors results in the decalcification of patch-reefs under business-as-usual scenarios and reduced, although positive, calcification under reduced-emission scenarios. Primary productivity was found to remain constant across all scenarios, despite significant bleaching and coral mortality under both future scenarios. Daylight calcification decreased and nocturnal decalcification increased sharply from the preindustrial and control conditions to the future scenarios of low (reduced emissions) and high (business-as-usual) increases in pCO2. These changes coincided with deeply negative carbonate budgets, a shift toward smaller carbonate sediments, and an increase in the abundance of sediment microbes under the business-as-usual emission scenario. Experimental coral reefs demonstrated highest net calcification rates and lowest rates of coral mortality under preindustrial conditions, suggesting that reef processes may not have been able to keep pace with the relatively minor environmental changes that have occurred during the last century. Taken together, our results have serious implications for the future of coral reefs under business-as-usual environmental changes projected for the coming decades and century.

Considering Species Tolerance to Climate Change in Conservation Management at Little Cayman's Coral Reefs

NASA Astrophysics Data System (ADS)

Camp, E.; Manfrino, C.; Smith, D.; Suggett, D.

2013-05-01

There is growing evidence demonstrating that climate change, notably increased frequency and intensity of thermal anomalies combined with ocean acidification, will negatively impact the future growth and viability of many reef systems, including those in the Caribbean. One key question that remains unanswered is whether or not there are management options aimed at protecting coral species from these threats. Little Cayman (Cayman Islands) provides a rare opportunity to investigate global climate stressors without the confounding impact of local anthropogenic stressors. Our research has focused on two climate change issues: Firstly, we have identified species-specific coral bleaching susceptibility (and the influence of regulation upon this susceptibility) to thermal anomalies. Species level of vulnerability to thermal anomalies can decrease when grown under variable temperature. Environmental variability may be key in influencing the susceptibility of corals to stress. The second part of our research has therefore addressed the variability in inorganic carbon chemistry that naturally occurs where certain reef building corals exist. We have identified how the inorganic carbon chemistry varies naturally among habitats and thus how corals within these habitats are potentially adapted to future acidification. Spatial, diurnal, lunar and seasonal variability have been identified as important factors with pCO2 values of up to 700-800 μatm and pH values as low as 7.801 for lagoon habitats, showing that some species are already being exposed to typical pCO2 and pH levels expected for the oceans in ~50 years' time. Using an eco-physiological approach, we are exploring how some reef-building corals are able to acclimate to more variable chemistry compared to others and whether this natural capacity installs increased tolerance to future acidification. These eco-physiological studies provide important information that can be utilized in a management framework. The aim of this framework will be to provide options to buffer or decrease the future impacts of global climate change on tropical coral reef systems.

Water flow and fin shape polymorphism in coral reef fishes.

PubMed

Binning, Sandra A; Roche, Dominique G

2015-03-01

Water flow gradients have been linked to phenotypic differences and swimming performance across a variety of fish assemblages. However, the extent to which water motion shapes patterns of phenotypic divergence within species remains unknown. We tested the generality of the functional relationship between swimming morphology and water flow by exploring the extent of fin and body shape polymorphism in 12 widespread species from three families (Acanthuridae, Labridae, Pomacentridae) of pectoral-fin swimming (labriform) fishes living across localized wave exposure gradients. The pectoral fin shape of Labridae and Acanthuridae species was strongly related to wave exposure: individuals with more tapered, higher aspect ratio (AR) fins were found on windward reef crests, whereas individuals with rounder, lower AR fins were found on leeward, sheltered reefs. Three of seven Pomacentridae species showed similar trends, and pectoral fin shape was also strongly related to wave exposure in pomacentrids when fin aspect ratios of three species were compared across flow habitats at very small spatial scales (<100 m) along a reef profile (reef slope, crest, and back lagoon). Unlike fin shape, there were no intraspecific differences in fish body fineless ratio across habitats or depths. Contrary to our predictions, there was no pattern relating species' abundances to polymorphism across habitats (i.e., abundance was not higher at sites where morphology is better adapted to the environment). This suggests that there are behavioral and/or physiological mechanisms enabling some species to persist across flow habitats in the absence of morphological differences. We suggest that functional relationships between swimming morphology and water flow not only structure species assemblages, but are yet another important variable contributing to phenotypic differences within species. The close links between fin shape polymorphism and local water flow conditions appear to be important for understanding species' distributions as well as patterns of diversification across environmental gradients.

Herbivory versus corallivory: are parrotfish good or bad for Caribbean coral reefs?

NASA Astrophysics Data System (ADS)

Mumby, Peter J.

2009-09-01

With coral cover in decline on many Caribbean reefs, any process of coral mortality is of potential concern. While sparisomid parrotfishes are major grazers of Caribbean reefs and help control algal blooms, the fact that they also undertake corallivory has prompted some to question the rationale for their conservation. Here the weight of evidence for beneficial effects of parrotfishes, in terms of reducing algal cover and facilitating demographic processes in corals, and the deleterious effects of parrotfishes in terms of causing coral mortality and chronic stress, are reviewed. While elevated parrotfish density will likely increase the predation rate upon juvenile corals, the net effect appears to be positive in enhancing coral recruitment through removal of macroalgal competitors. Parrotfish corallivory can cause modest partial colony mortality in the most intensively grazed species of Montastraea but the generation and healing of bite scars appear to be in near equilibrium, even when coral cover is low. Whole colony mortality in adult corals can lead to complete exclusion of some delicate, lagoonal species of Porites from forereef environments but is only reported for one reef species ( Porites astreoides), for one habitat (backreef), and with uncertain incidence (though likely <<10%). No deleterious effects of predation on coral growth or fecundity have been reported, though recovery of zooxanthellae after bleaching events may be retarded. The balance of evidence to date finds strong support for the herbivory role of parrotfishes in facilitating coral recruitment, growth, and fecundity. In contrast, no net deleterious effects of corallivory have been reported for reef corals. Corallivory is unlikely to constrain overall coral cover but contraints upon dwindling populations of the Montastraea annularis species complex are feasible and the role of parrotfishes as a vector of coral disease requires evaluation. However, any assertion that conservation practices should guard against protecting corallivorous parrotfishes appears to be unwarranted at this stage.

Earth Observations taken by the Expedition 18 Crew

NASA Image and Video Library

2009-01-06

ISS018-E-018129 (6 Jan. 2009) --- Atafu Atoll in the Southern Pacific Ocean is featured in this image photographed by an Expedition 18 crewmember on the International Space Station. At roughly eight kilometers wide, Atafu Atoll is the smallest of three atolls (with Nukunonu and Fakaofo atolls to the southeast, not shown) comprising the Tokelau Islands group located in the southern Pacific Ocean. Swains Island to the south (not shown) is also considered part of the Tokelau group. The political entity of Tokelau is currently a territory of New Zealand. In recent years, public referendums on independence within the islands have been held, but have not received sufficient support to move forward. The primary settlement on Atafu is a village located at the northwestern corner of the atoll ? indicated by an area of light gray dots in this photograph. The typical ring shape of the atoll is the result of coral reefs building up around a former volcanic island. Over geologic time, the central volcano has subsided beneath the water surface, leaving the fringing reefs and a central lagoon that contains submerged coral reefs. Erosion and soil development on the surfaces of the exposed fringing reefs has lead to formation of tan to light brown beach deposits (southern and western sides of the atoll) and green vegetation cover (northern and eastern sides of the atoll). The Tokelau Islands, including Atafu Atoll, suffered significant inundation and erosion during Tropical Cyclone Percy in 2005. The approximate elevation of Atafu Atoll is only two meters above the tidal high water level. Vulnerability to tropical cyclones and potential sea level rise makes the long-term habitability of the atoll uncertain.

Blacktip reef sharks, Carcharhinus melanopterus, have high genetic structure and varying demographic histories in their Indo-Pacific range.

PubMed

Vignaud, Thomas M; Mourier, Johann; Maynard, Jeffrey A; Leblois, Raphael; Spaet, Julia; Clua, Eric; Neglia, Valentina; Planes, Serge

2014-11-01

For free-swimming marine species like sharks, only population genetics and demographic history analyses can be used to assess population health/status as baseline population numbers are usually unknown. We investigated the population genetics of blacktip reef sharks, Carcharhinus melanopterus; one of the most abundant reef-associated sharks and the apex predator of many shallow water reefs of the Indian and Pacific Oceans. Our sampling includes 4 widely separated locations in the Indo-Pacific and 11 islands in French Polynesia with different levels of coastal development. Four-teen microsatellite loci were analysed for samples from all locations and two mitochondrial DNA fragments, the control region and cytochrome b, were examined for 10 locations. For microsatellites, genetic diversity is higher for the locations in the large open systems of the Red Sea and Australia than for the fragmented habitat of the smaller islands of French Polynesia. Strong significant structure was found for distant locations with FST values as high as ~0.3, and a smaller but still significant structure is found within French Polynesia. Both mitochondrial genes show only a few mutations across the sequences with a dominant shared haplotype in French Polynesia and New Caledonia suggesting a common lineage different to that of East Australia. Demographic history analyses indicate population expansions in the Red Sea and Australia that may coincide with sea level changes after climatic events. Expansions and flat signals are indicated for French Polynesia as well as a significant recent bottleneck for Moorea, the most human-impacted lagoon of the locations in French Polynesia. © 2014 John Wiley & Sons Ltd.

Incorporating seascape connectivity in conservation prioritisation.

PubMed

Weeks, Rebecca

2017-01-01

In conservation prioritisation, it is often implicit that representation targets for individual habitat types act as surrogates for the species that inhabit them. Yet for many commercially and ecologically important coral reef fish species, connectivity among different habitats in a seascape may be more important than any single habitat alone. Approaches to conservation prioritisation that consider seascape connectivity are thus warranted. I demonstrate an approach that can be implemented within a relatively data-poor context, using widely available conservation planning software. Based on clearly stated assumptions regarding species' habitat usage and movement ability, this approach can be adapted to different focal species and contexts, or refined as further data become available. I first derive a seascape connectivity metric based on area-weighted proximity between juvenile and adult habitat patches, and then apply this during spatial prioritisation using the decision-support software Marxan. Using a case study from Micronesia, I present two applications: first, to inform prioritisation for a network of marine protected areas to achieve regional objectives for habitat representation; and second, to identify nursery habitat patches that are most likely to supply juveniles to adult populations on reefs within existing protected areas. Incorporating seascape connectivity in conservation prioritisation highlights areas where small marine protected areas placed on coral reefs might benefit from proximity to other habitats in the seascape, and thus be more effective. Within the context of community tenure over resources, identification of critical nursery habitats to improve the effectiveness of existing marine protected areas indicates where collaboration across community boundaries might be required. Outputs from these analyses are likely to be most useful in regions where management is highly decentralised, imposing spatial constraints on the size of individual protected areas.

Incorporating seascape connectivity in conservation prioritisation

PubMed Central

2017-01-01

In conservation prioritisation, it is often implicit that representation targets for individual habitat types act as surrogates for the species that inhabit them. Yet for many commercially and ecologically important coral reef fish species, connectivity among different habitats in a seascape may be more important than any single habitat alone. Approaches to conservation prioritisation that consider seascape connectivity are thus warranted. I demonstrate an approach that can be implemented within a relatively data-poor context, using widely available conservation planning software. Based on clearly stated assumptions regarding species’ habitat usage and movement ability, this approach can be adapted to different focal species and contexts, or refined as further data become available. I first derive a seascape connectivity metric based on area-weighted proximity between juvenile and adult habitat patches, and then apply this during spatial prioritisation using the decision-support software Marxan. Using a case study from Micronesia, I present two applications: first, to inform prioritisation for a network of marine protected areas to achieve regional objectives for habitat representation; and second, to identify nursery habitat patches that are most likely to supply juveniles to adult populations on reefs within existing protected areas. Incorporating seascape connectivity in conservation prioritisation highlights areas where small marine protected areas placed on coral reefs might benefit from proximity to other habitats in the seascape, and thus be more effective. Within the context of community tenure over resources, identification of critical nursery habitats to improve the effectiveness of existing marine protected areas indicates where collaboration across community boundaries might be required. Outputs from these analyses are likely to be most useful in regions where management is highly decentralised, imposing spatial constraints on the size of individual protected areas. PMID:28753647

Vulnerability of inter-tropical littoral areas. Preface

NASA Astrophysics Data System (ADS)

Charvis, Philippe; Gubert, Flore; Ménard, Frédéric

2017-10-01

The coastal area is defined as the interface between land and sea. It is a transition zone where land is affected by its proximity to the sea, and the coastal sea is affected by its proximity to the land. Its components are diverse and include river deltas, coastal plains, wetlands, beaches and dunes, reefs, mangrove forests, lagoons, and other coastal features. Coastal areas contribute to a small proportion of the total land area in the Earth system, but they provide a wide variety of ecosystem services (e.g., food through fish production, sand mining, flooding and erosion protection, recreational benefits, etc.) and are home to a large and growing proportion of the world's population.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Tribble, G.W.; Sansone, F.J.; Li, Yuan-Hui

Hydraulic exchange between overlying sea water and the internal structure of a patch reef in Kaneohe Bay, Oahu, Hawaii, was studied with an array of wells, 1, 2, and 4 m deep. Two natural chemical tracers, radon, and salinity, were used to calculate the exchange rate between surface sea water and reef interstitial waters. Dissolved radon concentrations are substantially higher in interstitial waters than is surface water. The degree of radon enrichment is quantitatively related to the time elapsed since interstitial water had equilibrated with the atmosphere. Residence time estimates are 1-40 days, with deeper wells having slower exchange. Themore » average residence time for 1-m-deep wells was 2.1 days. A rainstorm-induced dilution of the salinity of Kaneohe Bay provides the second tracer. Samples of surface and reef interstitial waters following this salinity perturbation are used to calculate an average residence time of 2.6 days at a depth of 1 m and 42 days at a depth of 2 m. Three types of physical forces thought to cause exchange between surface and interstitial water are considered by measurement of the forcing functions and reef permeability. Hydraulic conductivities are about 50 m/d, with lower values near the seaward side of the reef. Most exchange seems to be caused by high-frequency, wave-driven oscillatory pumping and by unidirectional hydraulic head gradients (of uncertain origin) that are stable for at least 3-4 days. Wave-driven mixing is probably more important shallower in the reef, whereas head-driven flow may dominate deeper in the reef. Tidal pumping does not seem to contribute to exchange. All methods indicate that exchange in the upper part of Checker Reef is primarily through vertical exchange. The best estimate for the residence time of water at a depth of 1 m is 2 days. Water at depths of 204 m probably has a residence time of weeks to months. 49 refs., 8 figs., 6 tabs.« less

Subsurface Permian reef complexes of southern Tunisia: Shelf carbonate setting and paleogeographic implications

NASA Astrophysics Data System (ADS)

Zaafouri, Adel; Haddad, Sofiene; Mannaî-Tayech, Beya

2017-05-01

2-D seismic reflection sections, borehole data as well as published and unpublished data have been investigated to reconstruct the paleogeography of southern Tunisia during Middle to Late Permian times. Paleogeographical reconstruction based on the integration of petroleum well data and 2-D seismic facies interpretation shows three main depositional areas with very contrasting sedimentary pile. These are 1) a subsiding basin; 2) an outer shelf carbonate, and 3) an inner shelf carbonate. Based on typical electric responses of reef buildups to seismic wave, we shall urge that during Middle Permian times, the outer carbonate shelf was subject of reef barrier development. Lithology evidences from core samples show that reef framework correspond mainly to fossiliferous limestone and dolomite. The WNW-ESE recognized reef barrier led between latitudes 33° 10‧ 00″N and 33° 20‧ 00″N. The Tebaga of Medenine outcrop constitutes the northern-edge of this barrier. Westward it may be extended to Bir Soltane area whereas its extension eastward is still to be determined. Biogenic buildups took place preferentially over faulted Carboniferous and lower Paleozoic paleohighs resulting likely from the Hercynian orogeny. The subsiding basin is located north of Tebaga of Medenine outcrop where Upper Permian sedimentary sequence is made entirely of 4000 m deep marine green silty shale facies. These are ascribed to unorganized and chaotic reflectors. Inner carbonate shelf facies succession corresponds to a typical interbedding of shallow marine carbonate deposits, shale, dolomite, and anhydrite inducing parallel-layered of strong amplitude and good continuity reflectors. Also within the inner carbonate shelf patch reef or reef pinnacles have been identified based on their seismic signature particularly their low vertical development as compared to reef complexes. Southward, towards Sidi Toui area, the Upper Permian depositional sequence thins out and bears witness of land influences as entailed by the increase of silicoclastic sedimentary supply and the lack of marine fossil.

Oligocene and Early Miocene coral faunas from Iran: palaeoecology and palaeobiogeography

NASA Astrophysics Data System (ADS)

Schuster, F.; Wielandt, U.

Oligocene and Early Miocene coral assemblages from three sections of central Iran are investigated with respect to their palaeoecological and palaeobiogeographic implications. These corals are compared with faunas from the Mediterranean Tethys and the Indopacific. Associated larger foraminifers are used for biostratigraphy and to support the palaeoecological interpretation. The studied sections are situated in the foreland basins of the Iranian Plate which is structured into a fore-arc and a back-arc basin separated by a volcanic arc. The coral assemblages from Abadeh indicate a shallowing-upward trend. Infrequently distributed solitary corals at the base of the section indicate a turbid environment. Above, a distinct horizon characterised by a Leptoseris-Stylophora assemblage associated with lepidocyclinids and planktonic foraminifers is interpreted as maximum flooding surface. Small patch reefs with a Porites-Faviidae assemblage are a common feature of Late Oligocene to Early Miocene coral occurrences and indicate water depths of less than 20m. The diversity of the coral faunas shows marked differences. Oligocene corals from the Esfahan-Sirjan fore-arc basin comprise more than 45 species of 32 genera and occur in a wide range of environments. Early Miocene corals from the Qom back-arc basin are less frequent, show a lower diversity (13 genera with 15 species) and occur in single horizons or small patch reefs.

A century of ocean warming on Florida Keys coral reefs: historic in situ observations

USGS Publications Warehouse

Kuffner, Ilsa B.; Lidz, Barbara H.; Hudson, J. Harold; Anderson, Jeffery S.

2015-01-01

There is strong evidence that global climate change over the last several decades has caused shifts in species distributions, species extinctions, and alterations in the functioning of ecosystems. However, because of high variability on short (i.e., diurnal, seasonal, and annual) timescales as well as the recency of a comprehensive instrumental record, it is difficult to detect or provide evidence for long-term, site-specific trends in ocean temperature. Here we analyze five in situ datasets from Florida Keys coral reef habitats, including historic measurements taken by lighthouse keepers, to provide three independent lines of evidence supporting approximately 0.8 °C of warming in sea surface temperature (SST) over the last century. Results indicate that the warming observed in the records between 1878 and 2012 can be fully accounted for by the warming observed in recent decades (from 1975 to 2007), documented using in situ thermographs on a mid-shore patch reef. The magnitude of warming revealed here is similar to that found in other SST datasets from the region and to that observed in global mean surface temperature. The geologic context and significance of recent ocean warming to coral growth and population dynamics are discussed, as is the future prognosis for the Florida reef tract.

Growth history and intrinsic factors influence risk assessment at a critical life transition for a fish

NASA Astrophysics Data System (ADS)

Lönnstedt, O. M.; McCormick, M. I.

2011-09-01

Making the appropriate decision in the face of predation risk dictates the fate of prey, and predation risk is highest at life history boundaries such as settlement. At the end of the larval phase, most coral reef fishes enter patches of reef containing novel predators. Since vision is often obscured in the complex surroundings, chemical information released from damaged conspecific is used to forewarn prey of an active predator. However, larvae enter the reef environment with their own feeding and growth histories, which will influence their motivation to feed and take risks. The present study explored the link between recent growth, feeding history, current performance and behavioural risk taking in newly settling stages of a coral reef damselfish ( Pomacentrus amboinensis). Older and larger juveniles in good body condition had a stronger response to chemical alarm cues of injured conspecifics; these fish spent a longer time in shelter and displayed a more dramatic decrease in foraging behaviour than fish in lower body condition. Feeding experiments supported these findings and emphasized the importance of body condition in affecting risk assessment. Evidently, larval growth history and body condition influences the likelihood of taking risks under the threat of predation immediately after settlement, thereby affecting the probability of survival in P. amboinensis.

Understanding the murky history of the Coral Triangle: Miocene corals and reef habitats in East Kalimantan (Indonesia)

NASA Astrophysics Data System (ADS)

Santodomingo, Nadiezhda; Renema, Willem; Johnson, Kenneth G.

2016-09-01

Studies on ancient coral communities living in marginal conditions, including low light, high turbidity, extreme temperatures, or high nutrients, are important to understand the current structure of reefs and how they could potentially respond to global changes. The main goal of this study was to document the rich and well-preserved fossil coral fauna preserved in Miocene exposures of the Kutai Basin in East Kalimantan, Indonesia. Our collections include almost forty thousand specimens collected from 47 outcrops. Seventy-nine genera and 234 species have been identified. Three different coral assemblages were found corresponding to small patch reefs that developed under the influence of high siliciclastic inputs from the Mahakam Delta. Coral assemblages vary in richness, structure, and composition. Platy coral assemblages were common until the Serravallian (Middle Miocene), while branching coral assemblages became dominant in the Tortonian (Late Miocene). By the late Tortonian massive coral assemblages dominated, similar to modern-style coral framework. Our results suggest that challenging habitats, such as the Miocene turbid habitats of East Kalimantan, might have played an important role during the early diversification of the Coral Triangle by hosting a pool of resilient species more likely to survive the environmental changes that have affected this region since the Cenozoic. Further research that integrates fossil and recent turbid habitats may provide a glimpse into the dynamics and future of coral reefs as "typical" clear-water reefs continue to decline in most regions.

Aragonite saturation states and nutrient fluxes in coral reef sediments in Biscayne National Park, FL, USA

USGS Publications Warehouse

Lisle, John T.; Reich, Christopher D.; Halley, Robert B.

2014-01-01

Some coral reefs, such as patch reefs along the Florida Keys reef tract, are not showing significant reductions in calcification rates in response to ocean acidification. It has been hypothesized that this recalcitrance is due to local buffering effects from biogeochemical processes driven by seagrasses. We investigated the influence that pore water nutrients, dissolved inorganic carbon (DIC) and total alkalinity (TA) have on aragonite saturation states (Ωaragonite) in the sediments and waters overlying the sediment surfaces of sand halos and seagrass beds that encircle Alinas and Anniversary reefs in Biscayne National Park. Throughout the sampling period, sediment pore waters from both bottom types had lower oxidation/reduction potentials (ORP), with lower pH relative to the sediment surface waters. The majority (86.5%) of flux rates (n = 96) for ΣNOx–, PO43–, NH4+, SiO2, DIC and TA were positive, sometimes contributing significant concentrations of the respective constituents to the sediment surface waters. The Ωaragonite values in the pore waters (range: 0.18 to 4.78) were always lower than those in the overlying waters (2.40 to 4.46), and 52% (n = 48) of the values were aragonite in 75% (n = 16) of the samples, but increased it in the remainder. The elevated fluxes of nutrients, DIC and TA into the sediment–water interface layer negatively alters the suitability of this zone for the settlement and development of calcifying larvae, while enhancing the establishment of algal communities.

Identification and prevalence of coral diseases on three Western Indian Ocean coral reefs.

PubMed

Séré, Mathieu G; Chabanet, Pascale; Turquet, Jean; Quod, Jean-Pascal; Schleyer, Michael H

2015-06-03

Coral diseases have caused a substantial decline in the biodiversity and abundance of reef-building corals. To date, more than 30 distinct diseases of scleractinian corals have been reported, which cause progressive tissue loss and/or affect coral growth, reproductive capacity, recruitment, species diversity and the abundance of reef-associated organisms. While coral disease research has increased over the last 4 decades, very little is known about coral diseases in the Western Indian Ocean. Surveys conducted at multiple sites in Reunion, South Africa and Mayotte between August 2010 and June 2012 revealed the presence of 6 main coral diseases: black band disease (BBD), white syndrome (WS), pink line syndrome (PLS), growth anomalies (GA), skeleton eroding band (SEB) and Porites white patch syndrome (PWPS). Overall, disease prevalence was higher in Reunion (7.5 ± 2.2%; mean ± SE) compared to South Africa (3.9 ± 0.8%) and Mayotte (2.7 ± 0.3%). Across locations, Acropora and Porites were the genera most susceptible to disease. Spatial variability was detected in both Reunion and South Africa, with BBD and WS more prevalent on shallow than deep reefs. There was also evidence of seasonality in 2 diseases: the prevalence of BBD and WS was higher in summer than winter. This was the first study to investigate the ecology of coral diseases, providing both qualitative and quantitative data, on Western Indian Ocean reefs, and surveys should be expanded to confirm these patterns.

Impacts of category 5 tropical cyclone Fantala (April 2016) on Farquhar Atoll, Seychelles Islands, Indian Ocean

NASA Astrophysics Data System (ADS)

Duvat, Virginie K. E.; Volto, Natacha; Salmon, Camille

2017-12-01

This paper provides new insights on the impacts of a category 5 tropical cyclone on Indian Ocean atoll reef islands. Using multi-date aerial imagery and field observations, the contribution of tropical cyclone Fantala to shoreline and island change, and to sediment production and transport, was assessed on Farquhar Atoll, Seychelles Islands. Results show that the two largest islands (> 3 km2) only suffered limited land loss (- 1.19 to - 8.35%) while small islets lost 13.17 to 28.45% of their initial land area. Islands and islets exhibited contrasting responses depending on their location, topography and vegetation type. Depending on islands, the retreat of the vegetation line occurred either along all shorelines, or along ocean shoreline only. The structure (wooded vs. grassy) and origin (native vs. introduced) of the vegetation played a major role in island response. Five days after the cyclone, beach width and beach area were multiplied by 1.5 to 10, depending on the setting, and were interpreted as resulting from both sediment reworking and the supply of large amounts of fresh sediments by the reef outer slopes to the island system. Fourth months after the cyclone, extended sheets of loose sediments were still present on the reef flat and in inter-islet channels and shallow lagoon waters, indicating continuing sediment transfer to islands. As a reminder (see Section 3.1.4), beach width uncertainty equals to 6 m for all beach sections.

Habitat complexity and fish size affect the detection of Indo-Pacific lionfish on invaded coral reefs

NASA Astrophysics Data System (ADS)

Green, S. J.; Tamburello, N.; Miller, S. E.; Akins, J. L.; Côté, I. M.

2013-06-01

A standard approach to improving the accuracy of reef fish population estimates derived from underwater visual censuses (UVCs) is the application of species-specific correction factors, which assumes that a species' detectability is constant under all conditions. To test this assumption, we quantified detection rates for invasive Indo-Pacific lionfish ( Pterois volitans and P. miles), which are now a primary threat to coral reef conservation throughout the Caribbean. Estimates of lionfish population density and distribution, which are essential for managing the invasion, are currently obtained through standard UVCs. Using two conventional UVC methods, the belt transect and stationary visual census (SVC), we assessed how lionfish detection rates vary with lionfish body size and habitat complexity (measured as rugosity) on invaded continuous and patch reefs off Cape Eleuthera, the Bahamas. Belt transect and SVC surveys performed equally poorly, with both methods failing to detect the presence of lionfish in >50 % of surveys where thorough, lionfish-focussed searches yielded one or more individuals. Conventional methods underestimated lionfish biomass by ~200 %. Crucially, detection rate varied significantly with both lionfish size and reef rugosity, indicating that the application of a single correction factor across habitats and stages of invasion is unlikely to accurately characterize local populations. Applying variable correction factors that account for site-specific lionfish size and rugosity to conventional survey data increased estimates of lionfish biomass, but these remained significantly lower than actual biomass. To increase the accuracy and reliability of estimates of lionfish density and distribution, monitoring programs should use detailed area searches rather than standard visual survey methods. Our study highlights the importance of accounting for sources of spatial and temporal variation in detection to increase the accuracy of survey data from coral reef systems.

Coral distribution patterns in Miocene Reefs of Anguilla, Leeward Islands, West Indies

DOE Office of Scientific and Technical Information (OSTI.GOV)

Foster, A.B.; Johnson, K.G.

1988-01-01

Anguilla, a 27 by 5 km island at 18/sup 0/13'N, 63/sup 0/05'W, parallels the northwest edge of the Anguilla bank (St. Martin plateau) in the outer lesser Angilles volcanic arc, which was active from the Eocene to Oligocene. Except for scattered exposures of tuff or basalt, the island is composed predominantly of reefal limestones and marls of the 70-m thick, middle Miocene Anguilla Formation, deposited on a shallow inner shelf platform extending from volcanoes near St. Martin. The reef framework consists of branched and platy corals interspersed with calcareous sand lenses. Although the limestones have been uplifted and subjected tomore » minor faulting, little evidence supports extensive transport across a slope. Coral distribution patterns have been quantified across the reefal units by point-counting species occurrences at 0.16-m intervals within 1-m/sup 2/ quadrants placed haphazardly across vertical exposures. Eight coral species (of possibly 18 total) were recorded. Cluster analysis delineated four facies: (1) a low-diversity facies dominated by branched Porites, (2) an intermediate diversity facies dominated by branched Porites, (3) a high-diversity facies dominated by massive Montastraea, Siderastrea, and Porites, and (4) an intermediate diversity facies dominated by platy Porites. These facies consists of lenses, no more than 100 m long and 2 m high, arranged in no apparent regular sequence. Thus, they do not represent zones across a depth gradient. Comparisons with living Caribbean reefs suggests that the Anguilla Miocene reefs were similar to small, modern, backreef fringing and patch reefs near the San Blas Islands of Panama, reefs whose variable composition and patchy distribution depend largely on sedimentation and current patterns.« less

Reduced Diversity and High Sponge Abundance on a Sedimented Indo-Pacific Reef System: Implications for Future Changes in Environmental Quality

PubMed Central

Powell, Abigail; Smith, David J.; Hepburn, Leanne J.; Jones, Timothy; Berman, Jade; Jompa, Jamaluddin; Bell, James J.

2014-01-01

Although coral reef health across the globe is declining as a result of anthropogenic impacts, relatively little is known of how environmental variability influences reef organisms other than corals and fish. Sponges are an important component of coral reef fauna that perform many important functional roles and changes in their abundance and diversity as a result of environmental change has the potential to affect overall reef ecosystem functioning. In this study, we examined patterns of sponge biodiversity and abundance across a range of environments to assess the potential key drivers of differences in benthic community structure. We found that sponge assemblages were significantly different across the study sites, but were dominated by one species Lamellodysidea herbacea (42% of all sponges patches recorded) and that the differential rate of sediment deposition was the most important variable driving differences in abundance patterns. Lamellodysidea herbacea abundance was positively associated with sedimentation rates, while total sponge abundance excluding Lamellodysidea herbacea was negatively associated with rates of sedimentation. Overall variation in sponge assemblage composition was correlated with a number of variables although each variable explained only a small amount of the overall variation. Although sponge abundance remained similar across environments, diversity was negatively affected by sedimentation, with the most sedimented sites being dominated by a single sponge species. Our study shows how some sponge species are able to tolerate high levels of sediment and that any transition of coral reefs to more sedimented states may result in a shift to a low diversity sponge dominated system, which is likely to have subsequent effects on ecosystem functioning. PMID:24475041

Kenya.

PubMed

Obura, D O

2001-12-01

The Kenya coast is bathed by the northward-flowing warm waters of the East Africa Coastal Current, located between latitudes 1 and 5 degrees S. With a narrow continental shelf, the coastal marine environments are dominated by coral reefs, seagrass beds and mangroves, with large expanses of sandy substrates where river inputs from Kenya's two largest rivers, the Tana and Athi rivers, prevent the growth of coral reefs. The northern part of the coast is seasonally influenced by upwelling waters of the Somali Current, resulting in lower water temperatures for part of the year. The coast is made up of raised Pleistocene reefs on coastal plains and hills of sedimentary origin, which support native habitats dominated by scrub bush and remnant pockets of the forests that used to cover East Africa and the Congo basin. The marine environment is characterized by warm tropical conditions varying at the surface between 25 degrees C and 31 degrees C during the year, stable salinity regimes, and moderately high nutrient levels from terrestrial runoff and groundwater. The semi-diurnal tidal regime varies from 1.5 to 4 m amplitude from neap to spring tides, creating extensive intertidal platform and rocky-shore communities exposed twice-daily during low tides. Fringing reef crests dominate the whole southern coast and parts of the northern coast towards Somalia, forming a natural barrier to the wave energy from the ocean. Coral reefs form the dominant ecosystem along the majority of the Kenya coast, creating habitats for seagrasses and mangroves in the lagoons and creeks protected by the reef crests. Kenya's marine environment faces a number of threats from the growing coastal human population estimated at just under three million in 2000. Extraction of fish and other resources from the narrow continental shelf, coral reef and mangrove ecosystems increases each year with inadequate monitoring and management structures to protect the resource bases. Coastal development in urban and tourist centers proceeds with little regard for environmental and social impacts. With a faltering economy, industrial development in Mombasa proceeds with few checks on pollution and other impacts. In 1998 Kenya's coral reefs suffered 50-80% mortality from the El Niño-related coral bleaching event that affected the entire Indian Ocean. The institutional, human resource and legal infrastructure for managing the coastal environment has in the past been low, however these are rapidly improving with the revitalization of national institutions and the passing in 1999 of an Environment Act. Marine Protected Areas are the key tool currently used in management of marine ecosystems, and focus principally on coral reefs and biodiversity protection. New initiatives are underway to improve application of fisheries regulations, and to use Integrated Coastal Area Management (ICAM) as a framework for protecting marine and coastal environments.

Sediment studies at Bikini Atoll part 3. Inventories of some long-lived gamma-emitting radionuclides associated with lagoon surface sediments

DOE Office of Scientific and Technical Information (OSTI.GOV)

Noshkin, V.E.

1997-12-01

Surface sediment samples were collected during 1979 from 87 locations in the lagoon at Bikini Atoll. The collections were made to better define the concentrations and distribution of long-lived radionuclides associated with the bottom material and to show what modifications occurred to the composition of the surface sediment from the nuclear testing program conducted by the United States at the Atoll between 1946 and 1958. This is the last of three reports on Bikini sediment studies. In this report, we discuss the concentrations and inventories of the residual long-lived gamma-emitting radionuclides in sediments from the lagoon. The gamma-emitting radionuclides detectedmore » most frequently in sediments collected in 1979, in addition to Americium-241 ({sup 241}Am) (discussed in the second report of this series), included Cesium-137 ({sup 137}Cs), Bismuth-207 ({sup 207}Bi), Europium-155 ({sup 155}Eu), and Cobalt-60 ({sup 60}Co). Other man-made, gamma-emitting radionuclides such as Europium-152,154 ({sup 152,154}Eu), Antimony-125 ({sup 125}Sb), and Rhodium-101,102m ({sup 101,102m}Rh) were occasionally measured above detection limits in sediments near test site locations. The mean inventories for {sup 137}Cs, {sup 207}Ei, {sup 155}Eu, and {sup 60}Co in the surface 4 cm of the lagoon sediment to be 1.7, 0.56, 7.76, and 0.74 TBq, respectively. By June 1997, radioactive decay would reduce these values to 1.1, 0.38, 0.62, and 0.07 TBq, respectively. Some additional loss results from a combination of different processes that continuously mobilize and return some amount of the radionuclides to the water column. The water and dissolved constituents are removed from the lagoon through channels and exchange with the surface waters of the north equatorial Pacific Ocean. Highest levels of these radionuclides are found in surface deposits lagoonward of the Bravo Crater. Lowest concentrations and inventories are associated with sediment lagoonward of the eastern reef. The quantities in the 0-4 cm surface layer are estimated to be less than 35% of the total inventory to depth in the sediment column.« less

The natural history of Caroline Atoll, Southern Line Islands. Part I. History, physiography, botany, and isle descriptions

USGS Publications Warehouse

Kepler, A.K.; Kepler, C.B.

1994-01-01

conclusion: Lushly wooded Caroline Atoll, with the majority of its 39 islets (399 ha of land) either in near-pristine condition or having recovered remarkably from past disturbance, is one of the least spoiled atolls in the Pacific. Uninhabited, it harbors plant ecosystems and breeding seabirds (Pt. II) of national and international importance. Its marine and terrestrial ecosystems are prime outdoor ecological laboratories for research on geological processes including ground water, sea level changes, the dynamics of motu formation, fish poisoning, and numerous facets of ecology including plant succession and Pisonia growth rates. Caroline boasts prime coral reefs thickly studded with Tridacna clams, substantial numbers of coconut crabs, breeding sites for green turtles, wintering grounds for shorebirds including the rare Bristle-thighed Curlew, ancient Tuamotuan marae, and a crystalline, unpolluted lagoon. The variety, abundance, and quality of its flora and fauna qualify it for status as an officially recognized international preserve (Pt. II, Sect. G). Efforts toward its conservation have thus far been unsuccessful: in 1992 it was leased to a private French businessman who is currently fishing the reefs for commercial profit, as well as disturbing seabird, turtle and coconut crab populations.

The natural history of Caroline Atoll, Southern Line Islands. Part II. Seabirds, other terrestrial animals, and conservation

USGS Publications Warehouse

Kepler, C.B.; Kepler, A.K.; Ellis, D.H.

1994-01-01

conclusion: Lushly wooded Caroline Atoll, with the majority of its 39 islets (399 ha of land) either in near-pristine condition or having recovered remarkably from past disturbance, is one of the least spoiled atolls in the Pacific. Uninhabited, it harbors plant ecosystems and breeding seabirds (Pt. II) of national and international importance. Its marine and terrestrial ecosystems are prime outdoor ecological laboratories for research on geological processes including ground water, sea level changes, the dynamics of motu formation, fish poisoning, and numerous facets of ecology including plant succession and Pisonia growth rates. Caroline boasts prime coral reefs thickly studded with Tridacna clams, substantial numbers of coconut crabs, breeding sites for green turtles, wintering grounds for shorebirds including the rare Bristle-thighed Curlew, ancient Tuamotuan marae, and a crystalline, unpolluted lagoon. The variety, abundance, and quality of its flora and fauna qualify it for status as an officially recognized international preserve (Pt. II, Sect. G). Efforts toward its conservation have thus far been unsuccessful: in 1992 it was leased to a private French businessman who is currently fishing the reefs for commercial profit, as well as disturbing seabird, turtle and coconut crab populations.

Control of paleoshorelines by trench forebulge uplift, Loyalty Islands

NASA Astrophysics Data System (ADS)

Dickinson, William R.

2013-07-01

Unlike most tropical Pacific islands, which lie along island arcs or hotspot chains, the Loyalty Islands between New Caledonia and Vanuatu owe their existence and morphology to the uplift of pre-existing atolls on the flexural forebulge of the New Hebrides Trench. The configuration and topography of each island is a function of distance from the crest of the uplifted forebulge. Both Maré and Lifou are fully emergent paleoatolls upon which ancient barrier reefs form highstanding annular ridges that enclose interior plateaus representing paleolagoon floors, whereas the partially emergent Ouvea paleoatoll rim flanks a drowned remnant lagoon. Emergent paleoshoreline features exposed by island uplift include paleoreef flats constructed as ancient fringing reefs built to past low tide levels and emergent tidal notches incised at past high tide levels. Present paleoshoreline elevations record uplift rates of the islands since last-interglacial and mid-Holocene highstands in global and regional sea levels, respectively, and paleoreef stratigraphy reflects net Quaternary island emergence. The empirical uplift rates vary in harmony with theoretical uplift rates inferred from the different positions of the islands in transit across the trench forebulge at the trench subduction rate. The Loyalty Islands provide a case study of island environments controlled primarily by neotectonics.

Using unmanned aerial vehicle (UAV) surveys and image analysis in the study of large surface-associated marine species: a case study on reef sharks Carcharhinus melanopterus shoaling behaviour.

PubMed

Rieucau, G; Kiszka, J J; Castillo, J C; Mourier, J; Boswell, K M; Heithaus, M R

2018-06-01

A novel image analysis-based technique applied to unmanned aerial vehicle (UAV) survey data is described to detect and locate individual free-ranging sharks within aggregations. The method allows rapid collection of data and quantification of fine-scale swimming and collective patterns of sharks. We demonstrate the usefulness of this technique in a small-scale case study exploring the shoaling tendencies of blacktip reef sharks Carcharhinus melanopterus in a large lagoon within Moorea, French Polynesia. Using our approach, we found that C. melanopterus displayed increased alignment with shoal companions when distributed over a sandflat where they are regularly fed for ecotourism purposes as compared with when they shoaled in a deeper adjacent channel. Our case study highlights the potential of a relatively low-cost method that combines UAV survey data and image analysis to detect differences in shoaling patterns of free-ranging sharks in shallow habitats. This approach offers an alternative to current techniques commonly used in controlled settings that require time-consuming post-processing effort. This article is protected by copyright. All rights reserved. This article is protected by copyright. All rights reserved.

Management under uncertainty: guide-lines for incorporating connectivity into the protection of coral reefs

NASA Astrophysics Data System (ADS)

McCook, L. J.; Almany, G. R.; Berumen, M. L.; Day, J. C.; Green, A. L.; Jones, G. P.; Leis, J. M.; Planes, S.; Russ, G. R.; Sale, P. F.; Thorrold, S. R.

2009-06-01

The global decline in coral reefs demands urgent management strategies to protect resilience. Protecting ecological connectivity, within and among reefs, and between reefs and other ecosystems is critical to resilience. However, connectivity science is not yet able to clearly identify the specific measures for effective protection of connectivity. This article aims to provide a set of principles or practical guidelines that can be applied currently to protect connectivity. These ‘rules of thumb’ are based on current knowledge and expert opinion, and on the philosophy that, given the urgency, it is better to act with incomplete knowledge than to wait for detailed understanding that may come too late. The principles, many of which are not unique to connectivity, include: (1) allow margins of error in extent and nature of protection, as insurance against unforeseen or incompletely understood threats or critical processes; (2) spread risks among areas; (3) aim for networks of protected areas which are: (a) comprehensive and spread—protect all biotypes, habitats and processes, etc., to capture as many possible connections, known and unknown; (b) adequate—maximise extent of protection for each habitat type, and for the entire region; (c) representative—maximise likelihood of protecting the full range of processes and spatial requirements; (d) replicated—multiple examples of biotypes or processes enhances risk spreading; (4) protect entire biological units where possible (e.g. whole reefs), including buffers around core areas. Otherwise, choose bigger rather than smaller areas; (5) provide for connectivity at a wide range of dispersal distances (within and between patches), emphasising distances <20-30 km; and (6) use a portfolio of approaches, including but not limited to MPAs. Three case studies illustrating the application of these principles to coral reef management in the Bohol Sea (Philippines), the Great Barrier Reef (Australia) and Kimbe Bay (Papua New Guinea) are described.

Geology and biology of the "Sticky Grounds", shelf-margin carbonate mounds, and mesophotic ecosystem in the eastern Gulf of Mexico

NASA Astrophysics Data System (ADS)

Locker, Stanley D.; Reed, John K.; Farrington, Stephanie; Harter, Stacey; Hine, Albert C.; Dunn, Shane

2016-08-01

Shelf-margin carbonate mounds in water depths of 116-135 m in the eastern Gulf of Mexico along the central west Florida shelf were investigated using swath bathymetry, side-scan sonar, sub-bottom imaging, rock dredging, and submersible dives. These enigmatic structures, known to fisherman as the "Sticky Grounds", trend along slope, are 5-15 m in relief with base diameters of 5-30 m, and suggest widespread potential for mesophotic reef habitat along the west Florida outer continental shelf. Possible origins are sea-level lowstand coral patch reefs, oyster reefs, or perhaps more recent post-lowstand biohermal development. Rock dredging recovered bioeroded carbonate-rock facies comprised of bored and cemented bioclastics. Rock sample components included calcified worm tubes, pelagic sediment, and oysters normally restricted to brackish nearshore areas. Several reef sites were surveyed at the Sticky Grounds during a cruise in August 2010 with the R/V Seward Johnson using the Johnson-Sea-Link II submersible to ground truth the swath-sonar maps and to quantify and characterize the benthic habitats, benthic macrofauna, fish populations, and coral/sponge cover. This study characterizes for the first time this mesophotic reef ecosystem and associated fish populations, and analyzes the interrelationships of the fish assemblages, benthic habitats and invertebrate biota. These highly eroded rock mounds provide extensive hard-bottom habitat for reef invertebrate species as well as essential fish habitat for reef fish and commercially/recreationally important fish species. The extent and significance of associated living resources with these bottom types is particularly important in light of the 2010 Deepwater Horizon oil spill in the northeastern Gulf and the proximity of the Loop Current. Mapping the distribution of these mesophotic-depth ecosystems is important for quantifying essential fish habitat and describing benthic resources. These activities can improve ecosystem management and planning of future oil and gas activities in this outer continental shelf region.

Geology and biology of the "Sticky Grounds," shelf-margin carbonate mounds, and mesophotic ecosystem in the eastern Gulf of Mexico

USGS Publications Warehouse

Locker, Stanley D.; Reed, John K.; Farrington, Stephanie; Harter, Stacey; Hine, Albert C.; Dunn, Shane

2016-01-01

Shelf-margin carbonate mounds in water depths of 116–135 m in the eastern Gulf of Mexico along the central west Florida shelf were investigated using swath bathymetry, side-scan sonar, sub-bottom imaging, rock dredging, and submersible dives. These enigmatic structures, known to fisherman as the “Sticky Grounds”, trend along slope, are 5–15 m in relief with base diameters of 5–30 m, and suggest widespread potential for mesophotic reef habitat along the west Florida outer continental shelf. Possible origins are sea-level lowstand coral patch reefs, oyster reefs, or perhaps more recent post-lowstand biohermal development. Rock dredging recovered bioeroded carbonate-rock facies comprised of bored and cemented bioclastics. Rock sample components included calcified worm tubes, pelagic sediment, and oysters normally restricted to brackish nearshore areas. Several reef sites were surveyed at the Sticky Grounds during a cruise in August 2010 with the R/V Seward Johnson using the Johnson-Sea-Link II submersible to ground truth the swath-sonar maps and to quantify and characterize the benthic habitats, benthic macrofauna, fish populations, and coral/sponge cover. This study characterizes for the first time this mesophotic reef ecosystem and associated fish populations, and analyzes the interrelationships of the fish assemblages, benthic habitats and invertebrate biota. These highly eroded rock mounds provide extensive hard-bottom habitat for reef invertebrate species as well as essential fish habitat for reef fish and commercially/recreationally important fish species. The extent and significance of associated living resources with these bottom types is particularly important in light of the 2010 Deepwater Horizon oil spill in the northeastern Gulf and the proximity of the Loop Current. Mapping the distribution of these mesophotic-depth ecosystems is important for quantifying essential fish habitat and describing benthic resources. These activities can improve ecosystem management and planning of future oil and gas activities in this outer continental shelf region.

A study of lagoonal and estuarine processes and artificial habitats in the area of the John F. Kennedy Space Center

NASA Technical Reports Server (NTRS)

Poonai, P.

1974-01-01

In order to study the influence of an artificial habitat of discarded automobile tires upon the biomass in and around it, three sites were selected in the Banana River, one of which will serve as a control and the other two as locations for small tire reefs. Measurements and correlation studies of the biomasses and the species indicate that the biodynamics of the sites are appreciably the same in the three cases, that there are probably adequate populations at the lower trophic levels, that there are perhaps reduced numbers of upper level carnivores, and that it is likely that small artificial havens can contribute to an increase in populations of certain species of gamefish.

Influence of CDOM and particle composition on ocean color of the Eastern New Caledonia Lagoon during the CALIOPE cruises

NASA Astrophysics Data System (ADS)

Dupouy, Cécile; Röttgers, Rüdiger; Tedetti, Marc; Martias, Chloe; Murakami, Hiroshi; Doxaran, David; Lantoine, Francois; Rodier, Martine; Favareto, Luciane; Kampel, Milton; Goutx, Madeleine; Frouin, Robert J.

2014-11-01

Ocean color of tropical lagoons is dependent on bathymetry and bottom type, as well as input of coastal living and mineral particles and chromophoric dissolved organic matter (CDOM). The New Caledonia lagoon lies in the Southwestern Tropical Pacific around 21° 30'S and 166° 30'E, with a great marine biodiversity in UNESCO Heritage coral reefs, benthic sea grass, and benthic communities. They are largely connected to the open ocean in the southern and eastern parts, but only by narrow passes in the southwest part. The trophic state is linked to spatial variations in flushing times. High run offs due to rain carrying abundant chromophoric dissolved organic matter (CDOM) and particle loads may greatly impact the functioning of ecosystems while rivers and sewage effluents may induce localized impacts. Two oceanographic cruises (CALIOPE 1 in 2011 and CALIOPE 2 in 2014) were carried out off the Eastern Coast of New Caledonia during a calm dry period and during high winds, respectively. Multi- and hyper-spectral marine reflectance was measured with a SIMBADA instrument and a TRIOS radiometer system, together with inherent optical properties (total and CDOM absorption coefficients with a PSICAM, in situ absorption and scattering with an AC9, backscattering with a Hydroscat-6). Fluorescence of CDOM (EEM/PARAFAC) was measured on collected 0.2 μm filtered samples. In 2014, Satlantic and FieldSpec hyper-spectral radiometers were available for in-water profiling of upwelling radiance and downwelling irradiance and above-water reflectance measurements, respectively. Inherent and apparent optical data from the two cruises are compared and used to estimate ocean color algorithms performance and evaluate a Linear Matrix Inversion method, providing tools for remote sensing on this highly under-sampled coastal region of New Caledonia.

Optical Algorithms at Satellite Wavelengths for Total Suspended Matter in Tropical Coastal Waters.

PubMed

Ouillon, Sylvain; Douillet, Pascal; Petrenko, Anne; Neveux, Jacques; Dupouy, Cécile; Froidefond, Jean-Marie; Andréfouët, Serge; Muñoz-Caravaca, Alain

2008-07-10

Is it possible to derive accurately Total Suspended Matter concentration or its proxy, turbidity, from remote sensing data in tropical coastal lagoon waters? To investigate this question, hyperspectral remote sensing reflectance, turbidity and chlorophyll pigment concentration were measured in three coral reef lagoons. The three sites enabled us to get data over very diverse environments: oligotrophic and sediment-poor waters in the southwest lagoon of New Caledonia, eutrophic waters in the Cienfuegos Bay (Cuba), and sediment-rich waters in the Laucala Bay (Fiji). In this paper, optical algorithms for turbidity are presented per site based on 113 stations in New Caledonia, 24 stations in Cuba and 56 stations in Fiji. Empirical algorithms are tested at satellite wavebands useful to coastal applications. Global algorithms are also derived for the merged data set (193 stations). The performances of global and local regression algorithms are compared. The best one-band algorithms on all the measurements are obtained at 681 nm using either a polynomial or a power model. The best two-band algorithms are obtained with R412/R620, R443/R670 and R510/R681. Two three-band algorithms based on Rrs620.Rrs681/Rrs412 and Rrs620.Rrs681/Rrs510 also give fair regression statistics. Finally, we propose a global algorithm based on one or three bands: turbidity is first calculated from Rrs681 and then, if < 1 FTU, it is recalculated using an algorithm based on Rrs620.Rrs681/Rrs412. On our data set, this algorithm is suitable for the 0.2-25 FTU turbidity range and for the three sites sampled (mean bias: 3.6 %, rms: 35%, mean quadratic error: 1.4 FTU). This shows that defining global empirical turbidity algorithms in tropical coastal waters is at reach.

The Life of a Sponge in a Sandy Lagoon.

PubMed

Ilan, M; Abelson, A

1995-12-01

Infaunal soft-bottom invertebrates benefit from the presence of sediment, but sedimentation is potentially harmful for hard-bottom dwellers. Most sponges live on hard bottom, but on coral reefs in the Red Sea, the species Biemna ehrenbergi (Keller, 1889) is found exclusively in soft-bottom lagoons, usually in the shallowest part. This location is a sink environment, which increases the deposition of particulate organic matter. Most of the sponge body is covered by sediment, but the chimney-like siphons protrude from the sediment surface. The sponge is attached to the buried beach-rock, which reduces the risk of dislodgment during storms. Dye injected above and into the sediment revealed, for the first time, a sponge pumping interstitial water (rich with particles and nutrients) into its aquiferous system. Visual examination of plastic replicas of the aquiferous system and electron microscopical analysis of sponge tissue revealed that the transcellular ostia are mostly located on the buried surface of the sponge. The oscula, however, are located on top of the siphons; their elevated position and their ability to close combine to prevent the filtering system outflow from clogging. The transcellular ostia presumably remain open due to cellular mobility. The sponge maintains a large population of bacteriocytes, which contains bacteria of several different species. Some of these bacteria disintegrate, and may be consumed by the sponge.

Dissolved organic carbon in coral-reef lagoons, by high temperature catalytic oxidation and UV spectrometry

NASA Astrophysics Data System (ADS)

Pagès, Jean; Torréton, Jean-Pascal; Sempéré, Richard

1997-06-01

Two surveys were carried out on ten atolls in the Tuamotu archipelago (French Polynesia, Pacific Ocean). In vitro UV (250-400 nm) spectra of water samples gave absorption at 254 nm, A 254, and spectrum slope, S ⋆ (computed from In A λ versus λ).These two descriptors are negatively correlated, and data points are arrayed along a hyperbola spanned between an oceanic pole (high S ⋆, low A 254) and a confined pole (low 5 ⋆, high A 254). Dissolved organic carbon (DOC) concentrations, [C], as assessed by HTCO, exhibit a narrow range (0.7-1.0 mg C.L -1 for most lagoons) contrasting with the wide diversity of optical characteristics. [C] and A 254 are positively correlated, with a significant intercept (0.5 mg C.L -1) representing non-chromophoric DOC. Carbon-specific absorption, ɛ 254 increases (from 0.4 to 1.3 m 2.g -1) with increasing [C], mainly according to the literature) owing to increased average molecular weight (MW) of the chromophoric DOC fraction, which also lowers S ⋆. Our optical data thus illustrate a gradient of confinement (or residence time) that corresponds to a continuum in DOC nature, especially in MW and hence in bioavailability. Optical methods are confirmed as quick and effective means of assessing DOM distribution.

TIMS U-series dating and stable isotopes of the last interglacial event in Papua New Guinea

DOE Office of Scientific and Technical Information (OSTI.GOV)

Stein, M.; Wasserburg, G.J.; Chen, J.H.

1993-06-01

The extensive flight of uplifted reef terraces which occurs along the Vitiaz strait on the northern flank of the Huon Peninsula in PNG (Papua New Guinea) contains a particularly good record of sea level changes in the last 250 ky. The Huon terraces were the target of an international expedition which took place in July--August 1988. In particular, the authors searched for suitable samples for U-series dating in a reef complex designated as VII, which is correlated with the last interglacial episode and high sea level stand. This complex is composed of a barrier reef (VIIb), a lagoon, and amore » fringing reef (VIIa). Twelve corals from these terraces and two corals from the older reef complex VIII were selected for analysis. The petrography, oxygen and carbon isotope compositions, and magnesium and strontium concentrations were determined along with the concentrations and isotopic compositions of uranium and thorium. The simplest model for sea level height for terrace VII is a continuous rise between 134 and 118 ky. Alternatively, there may have been two periods of rapid sea level rise. In contrast, in the Bahamas, there is evidence that sea level remained rather constant over the time interval 132 to 120 ky. The absence of ages between 132 and 120 ky in PNG could be the result of changes in the local tectonic uplift rates during that time, or erosion that disrupted the continuous record. In any event, the authors find no basis for accepting a single brief time for the age of the last interglacial and applying this age as a precise chronometer for worldwide correlation, or as a test of climatic models. The older ages reported here precede the Milankovitch solar insolation peak at 128 ky, and the younger ages are [approximately]10 ky after this peak. If the present high-precision data are correct, then it will be necessary to reassess the validity of the Milankovitch theory of climatic changes. 76 refs., 6 figs., 6 tabs.« less

Individual consistency in the behaviors of newly-settled reef fish

PubMed Central

Meekan, Mark G.; McCormick, Mark I.

2015-01-01

Flexibility in behavior is advantageous for organisms that transition between stages of a complex life history. However, various constraints can set limits on plasticity, giving rise to the existence of personalities that have associated costs and benefits. Here, we document a field and laboratory experiment that examines the consistency of measures of boldness, activity, and aggressive behavior in the young of a tropical reef fish, Pomacentrus amboinensis (Pomacentridae) immediately following their transition between pelagic larval and benthic juvenile habitats. Newly-settled fish were observed in aquaria and in the field on replicated patches of natural habitat cleared of resident fishes. Seven behavioral traits representing aspects of boldness, activity and aggression were monitored directly and via video camera over short (minutes), medium (hours), and long (3 days) time scales. With the exception of aggression, these behaviors were found to be moderately or highly consistent over all time scales in both laboratory and field settings, implying that these fish show stable personalities within various settings. Our study is the first to examine the temporal constancy of behaviors in both field and laboratory settings in over various time scales at a critically important phase during the life cycle of a reef fish. PMID:26020013

Individual consistency in the behaviors of newly-settled reef fish.

PubMed

White, James R; Meekan, Mark G; McCormick, Mark I

2015-01-01

Flexibility in behavior is advantageous for organisms that transition between stages of a complex life history. However, various constraints can set limits on plasticity, giving rise to the existence of personalities that have associated costs and benefits. Here, we document a field and laboratory experiment that examines the consistency of measures of boldness, activity, and aggressive behavior in the young of a tropical reef fish, Pomacentrus amboinensis (Pomacentridae) immediately following their transition between pelagic larval and benthic juvenile habitats. Newly-settled fish were observed in aquaria and in the field on replicated patches of natural habitat cleared of resident fishes. Seven behavioral traits representing aspects of boldness, activity and aggression were monitored directly and via video camera over short (minutes), medium (hours), and long (3 days) time scales. With the exception of aggression, these behaviors were found to be moderately or highly consistent over all time scales in both laboratory and field settings, implying that these fish show stable personalities within various settings. Our study is the first to examine the temporal constancy of behaviors in both field and laboratory settings in over various time scales at a critically important phase during the life cycle of a reef fish.

Species profiles: Life histories and environmental requirements of coastal fishes and invertebrates (south Florida): Long-spined Black Sea urchin. [Diadema antillarum

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ogden, J.C.; Carpenter, R.C.

1987-08-01

The long-spined black sea urchin, Diadema antillarum, is one of the most common marine invertebrates in the South Florida and Caribbean regions. Diadema is gregarious and is found in large groups on hard bottom in shallow waters. Spawning is year-round, concentrated in late winter to early summer, and the larvae spend an unknown period in the plankton. Following settlement, growth is rapid, to a maximum size of about 10 cm in 3 to 4 years. Diadema is a grazer, feeding on small algal filaments and on seagrass, and tends to be active at night. Grazing activities can produce grazed halosmore » around patch reefs in the vicinity of seagrass beds. Many experiments have indicated the importance of this grazing in the coexistence of species on the reef and in maintaining high biological productivity. In 1983-84, Diadema suffered an unprecedented mass mortality and its populations were reduced by up to 98% throughout its range. The elimination of Diadema has affected algal biomass, reef productivity, and fish populations. Diadema populations are slowly beginning to increase, but complete recovery may take years.« less

Key Largo Limestone revisited: Pleistocene shelf-edge facies, Florida Keys, USA

USGS Publications Warehouse

Gray, Multer H.; Gischler, E.; Lundberg, J.; Simmons, K.R.; Shinn, E.A.

2002-01-01

New dates and analysis of 12 deep and 57 shallow cores allow a more detailed interpretation of the Pleistocene shelf edge of the Florida Platform as found in various facies of the Key Largo Limestone beneath the Florida Keys. In this study a three-phase evolution of the Quaternary units (Q1-Q5) of the Key Largo is presented with new subdivision of the Q5. (1) In the first phase, the Q1 and Q2 (perhaps deposited during oxygen-isotope stage 11) deep-water quartz-rich environment evolved into a shallow carbonate phase. (2) Subsequently, a Q3 (presumably corresponding to oxygen-isotope stage 9) flourishing reef and productive high-platform sediment phase developed. (3) Finally, a Q4 and Q5 (corresponding to oxygen-isotope stages 7 and 5) stabilization phase occured with reefs and leeward productive lagoons, followed by lower sea levels presenting a sequence of younger (isotope substages 5c, 5a) shelf-margin wedges, sediment veneers and outlier reefs. The Key Largo Limestone provides an accessible model of a carbonate shelf edge with fluctuating water depth, bordering a deep seaward basin for a period of at least 300 ka. During this time, at least four onlaps/offlaps, often separated by periods of karst development with associated diagenetic alterations, took place. The story presented by this limestone not only allows a better understanding of the history of south Florida but also aids in the interpretation of similar persistent shelf-edge sites bordering deep basins in other areas.

The Miocene Nullarbor Limestone, southern Australia; deposition on a vast subtropical epeiric platform

NASA Astrophysics Data System (ADS)

O'Connell, Laura G.; James, Noel P.; Bone, Yvonne

2012-05-01

The early to middle Miocene Nullarbor Limestone forms the vast, karsted Nullarbor Plain in southern Australia, and may be the most extensive Miocene carbonate deposit described to date. These carbonates were deposited at southern paleolatitudes of ~ 40°S and are interpreted to be subtropical to warm-temperate in character because of the presence of certain genera of tropical coralline algae (rhodoliths and articulated types), large benthic foraminifera, tropical molluscs, zooxanthellate corals, and micrite envelopes. Facies are dominated by skeletal grainstones and floatstones that accumulated in three interpreted paleoenvironments: (1) seagrass banks (upper photic zone), (2) rhodolith pavements (lower photic zone), and (3) open seafloors (lower photic to subphotic zone). A decrease of tropical components from west to east across the platform implies that warm oceanic currents (possibly related to a proto-Leeuwin Current), as well as a period of warm climate (Miocene Climatic Optimum), resulted in subtropical deposition at southern latitudes. The Southern Ocean extended inboard ~ 450 km from the shelf edge during Nullarbor Limestone deposition, but interpreted paleodepths did not extend much below the base of the photic zone. A small slope angle (~ 0.02°) over a wide shelf (~ 300,000 km2) implies deposition on an epeiric platform or epeiric ramp. A Miocene barrier reef was likely coeval with Nullarbor Limestone deposition. Therefore, the inboard portion of the Nullarbor Limestone can be considered part of an extensive back-reef lagoon system on a rimmed epeiric platform, perhaps attaining a size similar to the modern Great Barrier Reef system.

Applications of fractals in ecology.

PubMed

Sugihara, G; M May, R

1990-03-01

Fractal models describe the geometry of a wide variety of natural objects such as coastlines, island chains, coral reefs, satellite ocean-color images and patches of vegetation. Cast in the form of modified diffusion models, they can mimic natural and artificial landscapes having different types of complexity of shape. This article provides a brief introduction to fractals and reports on how they can be used by ecologists to answer a variety of basic questions, about scale, measurement and hierarchy in, ecological systems. Copyright © 1990. Published by Elsevier Ltd.

Submesoscale tidal eddies in the wake of coral islands and reefs: satellite data and numerical modelling

NASA Astrophysics Data System (ADS)

Delandmeter, Philippe; Lambrechts, Jonathan; Marmorino, George O.; Legat, Vincent; Wolanski, Eric; Remacle, Jean-François; Chen, Wei; Deleersnijder, Eric

2017-07-01

Interaction of tidal flow with a complex topography and bathymetry including headlands, islands, coral reefs and shoals create a rich submesoscale field of tidal jets, vortices, unsteady wakes, lee eddies and free shear layers, all of which impact marine ecology. A unique and detailed view of the submesoscale variability in a part of the Great Barrier Reef lagoon, Australia, that includes a number of small islands was obtained by using a "stereo" pair of 2-m-resolution visible-band images that were acquired just 54 s apart by the WorldView-3 satellite. Near-surface current and vorticity were extracted at a 50-m-resolution from those data using a cross-correlation technique and an optical-flow method, each yielding a similar result. The satellite-derived data are used to test the ability of the second-generation Louvain-la-Neuve ice-ocean model (SLIM), an unstructured-mesh, finite element model for geophysical and environmental flows, to reproduce the details of the currents in the region. The model succeeds in simulating the large-scale (> 1 km) current patterns, such as the main current and the width and magnitude of the jets developing in the gaps between the islands. Moreover, the order of magnitude of the vorticity and the occurrence of some vortices downstream of the islands are correctly reproduced. The smaller scales (< 500 m) are resolved by the model, although various discrepancies with the data are observed. The smallest scales (< 50 m) are unresolved by both the model- and image-derived velocity fields. This study shows that high-resolution models are able to a significant degree to simulate accurately the currents close to a rugged coast. Very-high-resolution satellite oceanography stereo images offer a new way to obtain snapshots of currents near a complex topography that has reefs, islands and shoals, and is a potential resource that could be more widely used to assess the predictive ability of coastal circulation models.

Sediment transport and mixing depth on a coral reef sand apron

NASA Astrophysics Data System (ADS)

Vila-Concejo, Ana; Harris, Daniel L.; Power, Hannah E.; Shannon, Amelia M.; Webster, Jody M.

2014-10-01

This paper investigates the mechanics of sediment transport on a subtidal sand apron located on a coral reef environment. In this environment 100% of the sediment is carbonate bioclasts generated in situ. The sand apron is located on the back reef and only affected by waves during high tides. It is commonly accepted in the literature that sand aprons are features that prograde lagoonwards and that most of the progradation occurs during high-energy events. Measurements of water depths, waves, currents and near bed suspended sediment concentrations (all at 10 Hz) on the sand apron were undertaken over a nine day intensive field campaign over both spring and neap tides; waves and tides were also measured in the lagoon. The topography and bathymetry of the sand apron were measured and mixing depth was obtained on three transects using depth of disturbance rods. We found that sediment transport on sand aprons is not solely restricted to high-energy events but occurs on a daily basis during spring tides. The main factor controlling the sediment transport was the water depth above the bed, with depths of 2-2.3 m allowing waves to promote the most sediment transport. This corresponds to a depth over the reef crest of 1.6-1.9 m. The second most important control was waves; transport was observed when Hs on the apron was 0.1 m or greater. In contrast, current magnitude was not a controlling mechanism for sediment entrainment but did affect sediment transport. The morphology of the sand apron was shown to affect the direction of currents with the currents also expected to influence the morphology of the sand apron. The currents measured during this field campaign were aligned with a shallow channel in the sand apron. Mixing depths were small (< 2.5 cm) yet they were larger than the values predicted by empirical formulae for gentle siliciclastic ocean beaches.

Community- and government-managed marine protected areas increase fish size, biomass and potential value

PubMed Central

Chirico, Angelica A. D.; McClanahan, Timothy R.; Eklöf, Johan S.

2017-01-01

Government-managed marine protected areas (MPAs) can restore small fish stocks, but have been heavily criticized for excluding resource users and creating conflicts. A promising but less studied alternative are community-managed MPAs, where resource users are more involved in MPA design, implementation and enforcement. Here we evaluated effects of government- and community-managed MPAs on the density, size and biomass of seagrass- and coral reef-associated fish, using field surveys in Kenyan coastal lagoons. We also assessed protection effects on the potential monetary value of fish; a variable that increases non-linearly with fish body mass and is particularly important from a fishery perspective. We found that two recently established community MPAs (< 1 km2 in size, ≤ 5 years of protection) harbored larger fish and greater total fish biomass than two fished (open access) areas, in both seagrass beds and coral reefs. As expected, protection effects were considerably stronger in the older and larger government MPAs. Importantly, across management and habitat types, the protection effect on the potential monetary value of the fish was much stronger than the effects on fish biomass and size (6.7 vs. 2.6 and 1.3 times higher value in community MPAs than in fished areas, respectively). This strong effect on potential value was partly explained by presence of larger (and therefore more valuable) individual fish, and partly by higher densities of high-value taxa (e.g. rabbitfish). In summary, we show that i) small and recently established community-managed MPAs can, just like larger and older government-managed MPAs, play an important role for local conservation of high-value fish, and that ii) these effects are equally strong in coral reefs as in seagrass beds; an important habitat too rarely included in formal management. Consequently, community-managed MPAs could benefit both coral reef and seagrass ecosystems and provide spillover of valuable fish to nearby fisheries. PMID:28806740

Community- and government-managed marine protected areas increase fish size, biomass and potential value.

PubMed

Chirico, Angelica A D; McClanahan, Timothy R; Eklöf, Johan S

2017-01-01

Government-managed marine protected areas (MPAs) can restore small fish stocks, but have been heavily criticized for excluding resource users and creating conflicts. A promising but less studied alternative are community-managed MPAs, where resource users are more involved in MPA design, implementation and enforcement. Here we evaluated effects of government- and community-managed MPAs on the density, size and biomass of seagrass- and coral reef-associated fish, using field surveys in Kenyan coastal lagoons. We also assessed protection effects on the potential monetary value of fish; a variable that increases non-linearly with fish body mass and is particularly important from a fishery perspective. We found that two recently established community MPAs (< 1 km2 in size, ≤ 5 years of protection) harbored larger fish and greater total fish biomass than two fished (open access) areas, in both seagrass beds and coral reefs. As expected, protection effects were considerably stronger in the older and larger government MPAs. Importantly, across management and habitat types, the protection effect on the potential monetary value of the fish was much stronger than the effects on fish biomass and size (6.7 vs. 2.6 and 1.3 times higher value in community MPAs than in fished areas, respectively). This strong effect on potential value was partly explained by presence of larger (and therefore more valuable) individual fish, and partly by higher densities of high-value taxa (e.g. rabbitfish). In summary, we show that i) small and recently established community-managed MPAs can, just like larger and older government-managed MPAs, play an important role for local conservation of high-value fish, and that ii) these effects are equally strong in coral reefs as in seagrass beds; an important habitat too rarely included in formal management. Consequently, community-managed MPAs could benefit both coral reef and seagrass ecosystems and provide spillover of valuable fish to nearby fisheries.

Contribution of a combined TDEM (Time-Domain electromagnetism) and geoelectrical survey to the investigation of the coastal aquifer of Puerto Morelos, Quintana Roo, Mexico

NASA Astrophysics Data System (ADS)

Rebolledo-Vieyra, M.; Ravelo-Cervantes, J. I.; Lecossec, A.

2007-12-01

This study reports initial results of combined Time Domain Electromagnetic (TDEM) and vertical electrical sounding (VES), geophysical characterization of the Quintana Roo coastal aquifer, with the aim of establishing effective protocols for subsequent surveys in the area, through the association of TDEM and VES. The high resistivity of the carbonate terrain, combined with the very low resistivity range of fresh-water and sea-water, are ideal to use both tools in combination. The results show that both methods used in a combination may provide a useful tool for hydrogeologial studies. In this survey we were able to identifiy a fracture 100 m x 40 m, that was correlated to fresh-water discharges in to the Puerto Morelos Reef lagoon.

Aura-biomes are present in the water layer above coral reef benthic macro-organisms.

PubMed

Walsh, Kevin; Haggerty, J Matthew; Doane, Michael P; Hansen, John J; Morris, Megan M; Moreira, Ana Paula B; de Oliveira, Louisi; Leomil, Luciana; Garcia, Gizele D; Thompson, Fabiano; Dinsdale, Elizabeth A

2017-01-01

As coral reef habitats decline worldwide, some reefs are transitioning from coral- to algal-dominated benthos with the exact cause for this shift remaining elusive. Increases in the abundance of microbes in the water column has been correlated with an increase in coral disease and reduction in coral cover. Here we investigated how multiple reef organisms influence microbial communities in the surrounding water column. Our study consisted of a field assessment of microbial communities above replicate patches dominated by a single macro-organism. Metagenomes were constructed from 20 L of water above distinct macro-organisms, including (1) the coral Mussismilia braziliensis , (2) fleshy macroalgae ( Stypopodium , Dictota and Canistrocarpus ), (3) turf algae, and (4) the zoanthid Palythoa caribaeorum and were compared to the water microbes collected 3 m above the reef. Microbial genera and functional potential were annotated using MG-RAST and showed that the dominant benthic macro-organisms influence the taxa and functions of microbes in the water column surrounding them, developing a specific "aura-biome". The coral aura-biome reflected the open water column, and was associated with Synechococcus and functions suggesting oligotrophic growth, while the fleshy macroalgae aura-biome was associated with Ruegeria , Pseudomonas, and microbial functions suggesting low oxygen conditions. The turf algae aura-biome was associated with Vibrio, Flavobacterium, and functions suggesting pathogenic activity, while zoanthids were associated with Alteromonas and functions suggesting a stressful environment. Because each benthic organism has a distinct aura-biome, a change in benthic cover will change the microbial community of the water, which may lead to either the stimulation or suppression of the recruitment of benthic organisms.

Aura-biomes are present in the water layer above coral reef benthic macro-organisms

PubMed Central

Haggerty, J. Matthew; Doane, Michael P.; Hansen, John J.; Morris, Megan M.; Moreira, Ana Paula B.; de Oliveira, Louisi; Leomil, Luciana; Garcia, Gizele D.; Thompson, Fabiano; Dinsdale, Elizabeth A.

2017-01-01

As coral reef habitats decline worldwide, some reefs are transitioning from coral- to algal-dominated benthos with the exact cause for this shift remaining elusive. Increases in the abundance of microbes in the water column has been correlated with an increase in coral disease and reduction in coral cover. Here we investigated how multiple reef organisms influence microbial communities in the surrounding water column. Our study consisted of a field assessment of microbial communities above replicate patches dominated by a single macro-organism. Metagenomes were constructed from 20 L of water above distinct macro-organisms, including (1) the coral Mussismilia braziliensis, (2) fleshy macroalgae (Stypopodium, Dictota and Canistrocarpus), (3) turf algae, and (4) the zoanthid Palythoa caribaeorum and were compared to the water microbes collected 3 m above the reef. Microbial genera and functional potential were annotated using MG-RAST and showed that the dominant benthic macro-organisms influence the taxa and functions of microbes in the water column surrounding them, developing a specific “aura-biome”. The coral aura-biome reflected the open water column, and was associated with Synechococcus and functions suggesting oligotrophic growth, while the fleshy macroalgae aura-biome was associated with Ruegeria, Pseudomonas, and microbial functions suggesting low oxygen conditions. The turf algae aura-biome was associated with Vibrio, Flavobacterium, and functions suggesting pathogenic activity, while zoanthids were associated with Alteromonas and functions suggesting a stressful environment. Because each benthic organism has a distinct aura-biome, a change in benthic cover will change the microbial community of the water, which may lead to either the stimulation or suppression of the recruitment of benthic organisms. PMID:28828261

Seagrass epiphytic assemblages are strong indicators of agricultural discharge but weak indicators of host features

NASA Astrophysics Data System (ADS)

Prado, Patricia

2018-05-01

Wastewater pulses from rice agriculture are persistently discharged into the northern shore of the Alfacs Bay (Ebro Delta, NW Mediterranean) from April to November. The bay also receives water from coastal lagoons which are subjected to freshwater inputs from the Ebro River mixed to an unknown extent with agricultural wastewater during the same period. This paper compares epiphyte assemblages growing on leaves of Cymodocea nodosa in sites exposed to agricultural drainage channels, lagoon connection channels, and control sites in the Ebro Delta Natural Park (southern shore of the bay). Leaf epiphytic assemblages of Zostera noltii patches in the northern shore of the bay were also compared with those of adjacent beds of C. nodosa. Drainage channel sites had consistently distinctive assemblages (higher species richness, biomass load, and taxa composition) than control sites. Assemblages from lagoon channel sites were more variable, with three sites showing particularly high covers of epiphytic algae and two sites more similar to controls. Epiphyte patterns clearly matched in situ measures of nutrient availability, and were consistent with decreased shoot densities in discharge sites. In contrast, differences in epiphyte assemblages between seagrass species were minor, and mostly a result of higher epiphytic loads on C. nodosa than on Z. noltii, which features thinner leaves. Further research is needed to investigate the consequences of these plant and epiphyte alterations in important ecosystem processes such as decomposition and export rates, as well as overall effects of nutrients and salinity in secondary producers such as associated macroinvertebrate assemblages supporting locally important marine fisheries.

Litterfall production of mangroves in the Huizache-Caimanero lagoon system, México

USGS Publications Warehouse

Flores-Cárdenas, Francisco; Hurtado-Oliva, Miguel Ángel; Doyle, Thomas W.; Nieves-Sotol, Mario; Díaz-Castro, Sara; Manzano-Sarabia, Marlenne

2017-01-01

The ecological legacy of the Huizache-Caimanero lagoon system has long been known as a trophically rich and productive ecosystem that supported artisanal fisheries of local and regional importance; however, a decline in fisheries' yields has been observed in recent decades. Mangroves are a fundamental component of this ecosystem, though data records and field studies are lacking in describing their structure and seasonal characteristics. Mangrove litterfall production was monitored during 2012–13 and described for the dominant species, Avicennia germinans (L.) Stearn and Laguncularia racemosa (L.) C.F. Gaertn. Forest surveys and monthly litter collections were obtained along a latitudinal gradient within the larger lagoon system to characterize the forest structure, leaf biomass, and related biological indicators (chlorophyll a concentration and Normalized Difference Vegetation Index [NDVI] estimated on leaf tissues). Results showed that structural characteristics (diameter at breast height, basal area, height, and crown diameter) were greater in Huizache, corresponding to patches with a dominance of A. germinans, while higher stem density was recorded for L. racemosa in Caimanero, comparatively similar to other mangrove habitat in NW Mexico. Litterfall was highest from May to October for both species. Litterfall production was also higher overall in 2012 in comparison to 2013, possibly corresponding with meteorological differences, most notably wind conditions. Annual litterfall production was similar by species across northern and southern Sinaloa. A contrast of the NDVI by site and species showed a wide interval, including low values for A. germinans, suggesting stress conditions for this species.

Linking removal targets to the ecological effects of invaders: a predictive model and field test.

PubMed

Green, Stephanie J; Dulvy, Nicholas K; Brooks, Annabelle M L; Akins, John L; Cooper, Andrew B; Miller, Skylar; Côté, Isabelle M

Species invasions have a range of negative effects on recipient ecosystems, and many occur at a scale and magnitude that preclude complete eradication. When complete extirpation is unlikely with available management resources, an effective strategy may be to suppress invasive populations below levels predicted to cause undesirable ecological change. We illustrated this approach by developing and testing targets for the control of invasive Indo-Pacific lionfish (Pterois volitans and P. miles) on Western Atlantic coral reefs. We first developed a size-structured simulation model of predation by lionfish on native fish communities, which we used to predict threshold densities of lionfish beyond which native fish biomass should decline. We then tested our predictions by experimentally manipulating lionfish densities above or below reef-specific thresholds, and monitoring the consequences for native fish populations on 24 Bahamian patch reefs over 18 months. We found that reducing lionfish below predicted threshold densities effectively protected native fish community biomass from predation-induced declines. Reductions in density of 25–92%, depending on the reef, were required to suppress lionfish below levels predicted to overconsume prey. On reefs where lionfish were kept below threshold densities, native prey fish biomass increased by 50–70%. Gains in small (<6 cm) size classes of native fishes translated into lagged increases in larger size classes over time. The biomass of larger individuals (>15 cm total length), including ecologically important grazers and economically important fisheries species, had increased by 10–65% by the end of the experiment. Crucially, similar gains in prey fish biomass were realized on reefs subjected to partial and full removal of lionfish, but partial removals took 30% less time to implement. By contrast, the biomass of small native fishes declined by >50% on all reefs with lionfish densities exceeding reef-specific thresholds. Large inter-reef variation in the biomass of prey fishes at the outset of the study, which influences the threshold density of lionfish, means that we could not identify a single rule of thumb for guiding control efforts. However, our model provides a method for setting reef-specific targets for population control using local monitoring data. Our work is the first to demonstrate that for ongoing invasions, suppressing invaders below densities that cause environmental harm can have a similar effect, in terms of protecting the native ecosystem on a local scale, to achieving complete eradication.

In-Situ Effects of Simulated Overfishing and Eutrophication on Benthic Coral Reef Algae Growth, Succession, and Composition in the Central Red Sea.

PubMed

Jessen, Christian; Roder, Cornelia; Villa Lizcano, Javier Felipe; Voolstra, Christian R; Wild, Christian

2013-01-01

Overfishing and land-derived eutrophication are major local threats to coral reefs and may affect benthic communities, moving them from coral dominated reefs to algal dominated ones. The Central Red Sea is a highly under-investigated area, where healthy coral reefs are contending against intense coastal development. This in-situ study investigated both the independent and combined effects of manipulated inorganic nutrient enrichment (simulation of eutrophication) and herbivore exclosure (simulation of overfishing) on benthic algae development. Light-exposed and shaded terracotta tiles were positioned at an offshore patch reef close to Thuwal, Saudi Arabia and sampled over a period of 4 months. Findings revealed that nutrient enrichment alone affected neither algal dry mass nor algae-derived C or N production. In contrast, herbivore exclusion significantly increased algal dry mass up to 300-fold, and in conjunction with nutrient enrichment, this total increased to 500-fold. Though the increase in dry mass led to a 7 and 8-fold increase in organic C and N content, respectively, the algal C/N ratio (18±1) was significantly lowered in the combined treatment relative to controls (26±2). Furthermore, exclusion of herbivores significantly increased the relative abundance of filamentous algae on the light-exposed tiles and reduced crustose coralline algae and non-coralline red crusts on the shaded tiles. The combination of the herbivore exclusion and nutrient enrichment treatments pronounced these effects. The results of our study suggest that herbivore reduction, particularly when coupled with nutrient enrichment, favors non-calcifying, filamentous algae growth with high biomass production, which thoroughly outcompetes the encrusting (calcifying) algae that dominates in undisturbed conditions. These results suggest that the healthy reefs of the Central Red Sea may experience rapid shifts in benthic community composition with ensuing effects for biogeochemical cycles if anthropogenic impacts, particularly overfishing, are not controlled.

In-Situ Effects of Simulated Overfishing and Eutrophication on Benthic Coral Reef Algae Growth, Succession, and Composition in the Central Red Sea

PubMed Central

Jessen, Christian; Roder, Cornelia; Villa Lizcano, Javier Felipe; Voolstra, Christian R.; Wild, Christian

2013-01-01

Overfishing and land-derived eutrophication are major local threats to coral reefs and may affect benthic communities, moving them from coral dominated reefs to algal dominated ones. The Central Red Sea is a highly under-investigated area, where healthy coral reefs are contending against intense coastal development. This in-situ study investigated both the independent and combined effects of manipulated inorganic nutrient enrichment (simulation of eutrophication) and herbivore exclosure (simulation of overfishing) on benthic algae development. Light-exposed and shaded terracotta tiles were positioned at an offshore patch reef close to Thuwal, Saudi Arabia and sampled over a period of 4 months. Findings revealed that nutrient enrichment alone affected neither algal dry mass nor algae-derived C or N production. In contrast, herbivore exclusion significantly increased algal dry mass up to 300-fold, and in conjunction with nutrient enrichment, this total increased to 500-fold. Though the increase in dry mass led to a 7 and 8-fold increase in organic C and N content, respectively, the algal C/N ratio (18±1) was significantly lowered in the combined treatment relative to controls (26±2). Furthermore, exclusion of herbivores significantly increased the relative abundance of filamentous algae on the light-exposed tiles and reduced crustose coralline algae and non-coralline red crusts on the shaded tiles. The combination of the herbivore exclusion and nutrient enrichment treatments pronounced these effects. The results of our study suggest that herbivore reduction, particularly when coupled with nutrient enrichment, favors non-calcifying, filamentous algae growth with high biomass production, which thoroughly outcompetes the encrusting (calcifying) algae that dominates in undisturbed conditions. These results suggest that the healthy reefs of the Central Red Sea may experience rapid shifts in benthic community composition with ensuing effects for biogeochemical cycles if anthropogenic impacts, particularly overfishing, are not controlled. PMID:23840570

Experimental evaluation of diversity-productivity relationships in a coral reef fish assemblage.

PubMed

Messmer, Vanessa; Blowes, Shane A; Jones, Geoffrey P; Munday, Philip L

2014-09-01

The global decline in biodiversity is causing increasing concern about the effects of biodiversity loss on ecosystem services such as productivity. Biodiversity has been hypothesised to be important in maintaining productivity of biological assemblages because niche complementarity and facilitation among the constituent species can result in more efficient use of resources. However, these conclusions are primarily based on studies with plant communities, and the relationship between diversity and productivity at higher trophic levels is largely unknown, especially in the marine environment. Here, we used a manipulative field experiment to test the effects of species richness and species identity on biomass accumulation in coral reef fish assemblages at Lizard Island. Small patch reefs were stocked with a total of 30 juveniles belonging to three planktivorous damselfish (genus Pomacentrus) according to three different levels of fish species richness (one, two and three species) and seven different combinations of fish species. Species richness had no effect on the relative growth in this assemblage after 18 days, but relative growth differed among individual fish species and the different combinations of species. Patterns of increase in biomass were best explained by species-specific differences and variable effects of intra- and interspecific competition on growth. These results suggest that niche complementarity and facilitation are not the most influential drivers of total productivity within this guild of planktivorous fishes. Total productivity may be resilient to declining reef fish biodiversity, but this will depend on which species are lost and on the life-history traits of remaining species.

Land use and land cover (LULC) of the Republic of the Maldives: first national map and LULC change analysis using remote-sensing data.

PubMed

Fallati, Luca; Savini, Alessandra; Sterlacchini, Simone; Galli, Paolo

2017-08-01

The Maldives islands in recent decades have experienced dramatic land-use change. Uninhabited islands were turned into new resort islands; evergreen tropical forests were cut, to be replaced by fields and new built-up areas. All these changes happened without a proper monitoring and urban planning strategy from the Maldivian government due to the lack of national land-use and land-cover (LULC) data. This study aimed to realize the first land-use map of the entire Maldives archipelago and to detect land-use and land-cover change (LULCC) using high-resolution satellite images and socioeconomic data. Due to the peculiar geographic and environmental features of the archipelago, the land-use map was obtained by visual interpretation and manual digitization of land-use patches. The images used, dated 2011, were obtained from Digital Globe's WorldView 1 and WorldView 2 satellites. Nine land-use classes and 18 subclasses were identified and mapped. During a field survey, ground control points were collected to test the geographic and thematic accuracy of the land-use map. The final product's overall accuracy was 85%. Once the accuracy of the map had been checked, LULCC maps were created using images from the early 2000s derived from Google Earth historical imagery. Post-classification comparison of the classified maps showed that growth of built-up and agricultural areas resulted in decreases in forest land and shrubland. The LULCC maps also revealed an increase in land reclamation inside lagoons near inhabited islands, resulting in environmental impacts on fragile reef habitat. The LULC map of the Republic of the Maldives produced in this study can be used by government authorities to make sustainable land-use planning decisions and to provide better management of land use and land cover.

The impact of low pH, low aragonite saturation state on calcifying corals: an in-situ study of ocean acidification from the "ojos" of Puerto Morelos, Mexico

NASA Astrophysics Data System (ADS)

Crook, E. D.; Paytan, A.; Potts, D. C.; Hernandez Terrones, L.; Rebolledo-Vieyra, M.

2010-12-01

Recent increases in atmospheric carbon dioxide have resulted in rising aqueous CO2 concentrations that lower the pH of the oceans (Caldeira and Wickett 2003, 2005, Doney et al., 2009). It is estimated that over the next 100 years, the pH of the surface oceans will decrease by ~0.4 pH units (Orr et al., 2005), which is expected to hinder the calcifying capabilities of numerous marine organisms. Previous field work (Hall-Spencer et al., 2008) indicates that ocean acidification will negatively impact calcifying species; however, to date, very little is known about the long-term impacts of ocean acidification from the in-situ study of coral reef ecosystems. The Yucatán Peninsula of Quintana Roo, Mexico, represents an ecosystem where naturally low pH groundwater (7.14-8.07) has been discharging offshore at highly localized points (called ojos) for millennia. We present preliminary chemical and biological data on a selection of ojos from lagoon sites in Puerto Morelos, Mexico. Our findings indicate a decrease in species richness and size with proximity to the low pH waters. We address the potential long-term implications of low pH, low aragonite saturation state on coral reef ecosystems.

Middle to late Holocene coastal evolution along the south coast of Upolu Island, Samoa

USGS Publications Warehouse

Goodwin, I.D.; Grossman, E.E.

2003-01-01

Stratigraphic surveys and sedimentological analyses of coastal sediments and reef cores along the south coast of Upolu Island, Samoa, reveal that during the middle Holocene this coast was characterised by barrier spits, open lagoons, and estuaries. These estuarine systems matured during the late Holocene, with progressive sedimentation and inlet closure, leading to the dominance of mangrove swamps in the past 1000 years. Contemporaneous with the transition of open estuaries to mangrove swamps was the aggradation and progradation of coastal plains. The coastal progradation since 700-1000 years BP is best explained by increased sediment availability and reduced incident wave energy at the shore resulting from the shallowing and subsequent cessation of reef crest accretion following the mid-Holocene sea-level highstand ca. ???4500 yr BP. A small relative sea-level (RSL) lowering since 700-1000 years may have contributed to the positive sediment budget. This study highlights the need for island-wide coastal surveys to assess the relative roles of RSL, sediment budgets, and hydrodynamics on coastal evolution and stability. Differences in coastal evolution around Upolu Island may also be influenced by differential tectonic movements associated with late Holocene volcanism, coseismicity, and/ or submarine landslides. ?? 2003 Elsevier B.V. All rights reserved.

Kiritimati, Kiribati (Christmas Island)

NASA Technical Reports Server (NTRS)

2002-01-01

Pronounced 'Ki-ris-mas,' Kiritimati Island has a large infilled lagoon that gives it the largest land area (125 square miles, 321 square km) of any atoll in the world. Captain Cook named the atoll Christmas Island when he arrived on Christmas Eve in 1777. Used for nuclear testing in the 1950s and 1960s, the island is now valued for its marine and wildlife resources. It is particularly important as a seabird nesting site-with an estimated 6 million birds using or breeding on the island, including several million Sooty Terns. Rainfall on Kiritimati is linked to El Nino patterns, with long droughts experienced between the wetter El Nino years. This image is based on a mosaic of four digital photographs taken on 16 January 2002 from the Space Station Alpha as part of the Crew Earth Observations Project. The underlying data have 10 meter spatial resolution. Coral reefs are one of the areas selected as a scientific theme for this project (see also the recent Earth Observatory article, Mapping the Decline of Coral Reefs. The mosaic, based on images ISS004-ESC-6249 to 6252, was provided by the Earth Sciences and Image Analysis Laboratory at Johnson Space Center. Additional images taken by astronauts and cosmonauts can be viewed at the NASA-JSC Gateway to Astronaut Photography of Earth.

Dynamics of a deep-water seagrass population on the Great Barrier Reef: annual occurrence and response to a major dredging program.

PubMed

York, Paul H; Carter, Alex B; Chartrand, Kathryn; Sankey, Tonia; Wells, Linda; Rasheed, Michael A

2015-08-17

Global seagrass research efforts have focused on shallow coastal and estuarine seagrass populations where alarming declines have been recorded. Comparatively little is known about the dynamics of deep-water seagrasses despite evidence that they form extensive meadows in some parts of the world. Deep-water seagrasses are subject to similar anthropogenic threats as shallow meadows, particularly along the Great Barrier Reef lagoon where they occur close to major population centres. We examine the dynamics of a deep-water seagrass population in the GBR over an 8 year period during which time a major capital dredging project occurred. Seasonal and inter-annual changes in seagrasses were assessed as well as the impact of dredging. The seagrass population was found to occur annually, generally present between July and December each year. Extensive and persistent turbid plumes from a large dredging program over an 8 month period resulted in a failure of the seagrasses to establish in 2006, however recruitment occurred the following year and the regular annual cycle was re-established. Results show that despite considerable inter annual variability, deep-water seagrasses had a regular annual pattern of occurrence, low resistance to reduced water quality but a capacity for rapid recolonisation on the cessation of impacts.

Dynamics of a deep-water seagrass population on the Great Barrier Reef: annual occurrence and response to a major dredging program

PubMed Central

York, Paul H.; Carter, Alex B.; Chartrand, Kathryn; Sankey, Tonia; Wells, Linda; Rasheed, Michael A.

2015-01-01

Global seagrass research efforts have focused on shallow coastal and estuarine seagrass populations where alarming declines have been recorded. Comparatively little is known about the dynamics of deep-water seagrasses despite evidence that they form extensive meadows in some parts of the world. Deep-water seagrasses are subject to similar anthropogenic threats as shallow meadows, particularly along the Great Barrier Reef lagoon where they occur close to major population centres. We examine the dynamics of a deep-water seagrass population in the GBR over an 8 year period during which time a major capital dredging project occurred. Seasonal and inter-annual changes in seagrasses were assessed as well as the impact of dredging. The seagrass population was found to occur annually, generally present between July and December each year. Extensive and persistent turbid plumes from a large dredging program over an 8 month period resulted in a failure of the seagrasses to establish in 2006, however recruitment occurred the following year and the regular annual cycle was re-established. Results show that despite considerable inter annual variability, deep-water seagrasses had a regular annual pattern of occurrence, low resistance to reduced water quality but a capacity for rapid recolonisation on the cessation of impacts. PMID:26279474

Plankton communities in the five Iles Eparses (Western Indian Ocean) considered to be pristine ecosystems

NASA Astrophysics Data System (ADS)

Bouvy, M.; Got, P.; Domaizon, I.; Pagano, M.; Leboulanger, C.; Bouvier, C.; Carré, C.; Roques, C.; Dupuy, C.

2016-04-01

Coral reef environments are generally recognized as being the most threatened of marine ecosystems. However, it is extremely difficult to distinguish the effects of climate change from other forcing factors, mainly because it is difficult to study ecosystems that are isolated from human pressure. The five Iles Eparses (Scattered Islands) are located in the Western Indian Ocean (WIO) and can be considered to be "pristine" ecosystems not subject to anthropogenic pressure. This study characterized their plankton assemblages for the first time, by determining the abundances of microbial (virus, bacteria, heterotrophic protists and phytoplankton) and metazooplankton communities in various lagoon and ocean sites around each island. The Europa lagoon has extensive, productive mangrove forests, which have the highest nutrient concentrations (nitrogen forms, dissolved organic carbon) and whose microbial communities present a peculiar structure and functioning. By means of bioassay experiments, we observed that bacterial production and growth rates are higher in Europa than those reported for the other islands. Tromelin, which lies outside the Mozambique Channel, had the lowest biological productivity, nutrient concentrations, and bacterial growth rates. Multivariate analysis indicated that distinct microbial assemblages occur in association to varying nutrient concentrations. Molecular fingerprinting showed clear discrimination of the structure of the archaea, bacteria and eukaryotes community between the sites. Our results suggest that the geographical distance can influence the diversity of dominant microbial taxa in the WIO.

An assessment of nutrients and sedimentation in the St. Thomas East End Reserves, US Virgin Islands.

PubMed

Pait, Anthony S; Galdo, Francis R; Ian Hartwell, S; Apeti, Dennis A; Mason, Andrew L

2018-04-09

Nutrients and sedimentation were monitored for approximately 2 years at six sites in the St. Thomas East End Reserves (STEER), St. Thomas, USVI, as part of a NOAA project to develop an integrated environmental assessment. Concentrations of ammonium (NH 4 + ) and dissolved inorganic nitrogen (DIN) were higher in Mangrove Lagoon and Benner Bay in the western portion of STEER than in the other sites further east (i.e., Cowpet Bay, Rotto Cay, St. James, and Little St. James). There was no correlation between rainfall and nutrient concentrations. Using a set of suggested nutrient thresholds that have been developed to indicate the potential for the overgrowth of algae on reefs, approximately 60% of the samples collected in STEER were above the threshold for orthophosphate (HPO 4 = ), while 55% of samples were above the DIN threshold. Benner Bay had the highest sedimentation rate of any site monitored in STEER, including Mangrove Lagoon. There was also an east to west and a north to south gradient in sedimentation, indicative of higher sedimentation rates in the western, more populated areas surrounding STEER, and sites closer to the shore of the main island of St. Thomas. Although none of the sites had a mean or average sedimentation rate above a suggested sedimentation threshold, the mean sedimentation rate in Benner Bay was just below the threshold.

Long-term field study of sea kraits in New Caledonia: fundamental issues and conservation.

PubMed

Bonnet, Xavier

2012-08-01

This short review focuses on the findings associated with a long-term field study on two species of sea kraits in New Caledonia. Since 2002, more than 30 sites in the lagoon have been sampled, and in most places mark-recapture was implemented. We collected detailed data on more than 14,000 marked individuals (>6000 recaptures) and used different techniques (stable isotopes, bio-logging, analyses of diet). The objective was fundamental: to examine how amphibious snakes cope with both terrestrial and aquatic environments. As access to abundant food is likely the main evolutionary driver for the return transition toward the sea in marine tetrapods, foraging ecology was an important part of the research and novel information was obtained on this subject. Rapidly however, field observations revealed the potential interest of sea kraits for conservation issues. Our results show that these snakes are useful bio-indicators of marine biodiversity; they also provide a useful signal to monitor levels of contamination by heavy metals in the lagoon, and more generally as a means of studying the functioning of reef ecosystems. Importantly, anecdotal observations (e.g., a krait drinking during rain) provided unsuspected physiological insights of general importance to fundamental problems and conservation. One of the lessons of this long-term study is that key results emerged in an unexpected way, but all were dependent on intensive field work.

Effects of season, sex and body size on the feeding ecology of turtle-headed sea snakes ( Emydocephalus annulatus) on IndoPacific inshore coral reefs

NASA Astrophysics Data System (ADS)

Goiran, C.; Dubey, S.; Shine, R.

2013-06-01

In terrestrial snakes, many cases of intraspecific shifts in dietary habits as a function of predator sex and body size are driven by gape limitation and hence are most common in species that feed on relatively large prey and exhibit a wide body-size range. Our data on sea snakes reveal an alternative mechanism for intraspecific niche partitioning, based on sex-specific seasonal anorexia induced by reproductive activities. Turtle-headed sea snakes ( Emydocephalus annulatus) on coral reefs in the New Caledonian Lagoon feed entirely on the eggs of demersal-spawning fishes. DNA sequence data (cytochrome b gene) on eggs that we palpated from stomachs of 37 snakes showed that despite this ontogenetic stage specialization, the prey comes from a taxonomically diverse array of species including damselfish (41 % of samples, at least 5 species), blennies (41 %, 4 species) and gobies (19 %, 5 species). The composition of snake diets shifted seasonally (with damselfish dominating in winter but not summer), presumably reflecting seasonality of fish reproduction. That seasonal shift affects male and female snakes differently, because reproduction is incompatible with foraging. Adult female sea snakes ceased feeding when they became heavily distended with developing embryos in late summer, and males ceased feeding while they were mate searching in winter. The sex divergence in foraging habits may be amplified by sexual size dimorphism; females grow larger than males, and larger snakes (of both sexes) feed more on damselfish (which often lay their eggs in exposed sites) than on blennies and gobies (whose eggs are hidden within narrow crevices). Specific features of reproductive biology of coral reef fish (seasonality and nest type) have generated intraspecific niche partitioning in these sea snakes, by mechanisms different from those that apply to terrestrial snakes.

Long-term growth rates and effects of bleaching in Acropora hyacinthus

NASA Astrophysics Data System (ADS)

Gold, Zachary; Palumbi, Stephen R.

2018-03-01

Understanding the response of coral growth to natural variation in the environment, as well as to acute temperature stress under current and future climate change conditions, is critical to predicting the future health of coral reef ecosystems. As such, ecological surveys are beginning to focus on corals that live in high thermal stress environments to understand how future coral populations may adapt to climate change. We investigated the relationship between coral growth, thermal microhabitat, symbionts type, and thermal acclimatization of four species of the Acropora hyacinthus complex in back-reef lagoons in American Samoa. Coral growth was measured from August 2010 to April 2016 using horizontal planar area of coral colonies derived from photographs and in situ maximum width measurements. Despite marked intraspecific variation, we found that planar colony growth rates were significantly different among cryptic species. The highly heat tolerant A. hyacinthus variant "HE" increased in area an average of 2.9% month-1 (0.03 cm average mean radial extension month-1). By contrast, the three less tolerant species averaged 6.1% (0.07 cm average mean radial extension month-1). Planar growth rates were 40% higher on average in corals harboring Clade C versus Clade D symbiont types, although marked inter-colony variation in growth rendered this difference nonsignificant. Planar growth rates for all four species dropped to near zero following a 2015 bleaching event, independent of the visually estimated percent area of bleaching. Within 1 yr, growth rates recovered to previous levels, confirming previous studies that found sublethal effects of thermal stress on coral growth. Long-term studies of individual coral colonies provide an important tool to measure impacts of environmental change and allow integration of coral physiology, genetics, symbionts, and microclimate on reef growth patterns.

Geologic assessment of undiscovered oil and gas resources—Lower Cretaceous Albian to Upper Cretaceous Cenomanian carbonate rocks of the Fredericksburg and Washita Groups, United States Gulf of Mexico Coastal Plain and State Waters

USGS Publications Warehouse

Swanson, Sharon M.; Enomoto, Catherine B.; Dennen, Kristin O.; Valentine, Brett J.; Cahan, Steven M.

2017-02-10

In 2010, the U.S. Geological Survey (USGS) assessed Lower Cretaceous Albian to Upper Cretaceous Cenomanian carbonate rocks of the Fredericksburg and Washita Groups and their equivalent units for technically recoverable, undiscovered hydrocarbon resources underlying onshore lands and State Waters of the Gulf Coast region of the United States. This assessment was based on a geologic model that incorporates the Upper Jurassic-Cretaceous-Tertiary Composite Total Petroleum System (TPS) of the Gulf of Mexico basin; the TPS was defined previously by the USGS assessment team in the assessment of undiscovered hydrocarbon resources in Tertiary strata of the Gulf Coast region in 2007. One conventional assessment unit (AU), which extends from south Texas to the Florida panhandle, was defined: the Fredericksburg-Buda Carbonate Platform-Reef Gas and Oil AU. The assessed stratigraphic interval includes the Edwards Limestone of the Fredericksburg Group and the Georgetown and Buda Limestones of the Washita Group. The following factors were evaluated to define the AU and estimate oil and gas resources: potential source rocks, hydrocarbon migration, reservoir porosity and permeability, traps and seals, structural features, paleoenvironments (back-reef lagoon, reef, and fore-reef environments), and the potential for water washing of hydrocarbons near outcrop areas.In Texas and Louisiana, the downdip boundary of the AU was defined as a line that extends 10 miles downdip of the Lower Cretaceous shelf margin to include potential reef-talus hydrocarbon reservoirs. In Mississippi, Alabama, and the panhandle area of Florida, where the Lower Cretaceous shelf margin extends offshore, the downdip boundary was defined by the offshore boundary of State Waters. Updip boundaries of the AU were drawn based on the updip extent of carbonate rocks within the assessed interval, the presence of basin-margin fault zones, and the presence of producing wells. Other factors evaluated were the middle Cenomanian sea-level fall and erosion that removed large portions of platform and platform-margin carbonate sediments in the Washita Group of central Louisiana. The production history of discovered reservoirs and well data within the AU were examined to estimate the number and size of undiscovered oil and gas reservoirs within the AU. Using the USGS National Oil and Gas Assessment resource assessment methodology, mean volumes of 40 million barrels of oil, 622 billion cubic feet of gas, and 14 million barrels of natural gas liquids are the estimated technically recoverable undiscovered resources for the Fredericksburg-Buda Carbonate Platform-Reef Gas and Oil AU.

Earth observations taken by the Expedition Seven crew

NASA Image and Video Library

2003-09-13

ISS007-E-14867 (13 September 2003) --- This view featuring Noumea, New Caledonia was taken by one of the Expedition 7 crewmembers onboard the International Space Station (ISS). The mountains forming the spine of the island of Grande Terre contain large reserves of nickel and chromium, and New Caledonia mines are one of the world’s greatest producers of nickel. This image shows details of New Caledonia’s main city, Noumea, which is built on a peninsula that juts into the lagoon on the southwest side of the island. The reefs here face localized problems from pollution and overfishing. The tourism industry is very important to the economy of Noumea, with extensive hotel development in the city and along the southeast coast of Grand Terre. The picture shows how urban development extends to the steep slopes of the coastal hills.

A Bayesian rupture model of the 2007 Mw 8.1 Solomon Islands earthquake in Southwest Pacific with coral reef displacement measurements

NASA Astrophysics Data System (ADS)

Chen, Ting; Luo, Haipeng; Furlong, Kevin P.

2017-05-01

On 1st April 2007 a Mw 8.1 megathrust earthquake occurred in the western Solomon Islands of the Southwest Pacific and generated a regional tsunami with run-up heights of up to 12 m. A Bayesian inversion model is constructed to derive fault dip angle and cumulative co-seismic and early post-seismic slip using coral reef displacement measurements, in which both data misfit and moment magnitude are used as constraints. Results show three shallow, high-slip patches concentrated along the trench from west of Ranongga Island to Rendova Island on a fault plane dipping 20°, and a maximum dip slip of 11.6 m beneath Ranongga Island. Considerable subsidence on Simbo Island outboard of the trench on the subducting plate is not well explained with this model, but may be related to the effects of afterslip and/or Simbo Island's location near the triple junction among the Australia, Woodlark and Pacific plates.

Late Pleistocene stratigraphy of a carbonate platform margin, Exumas, Bahamas

NASA Astrophysics Data System (ADS)

Aalto, K. R.; Dill, Robert F.

1996-05-01

Detailed field studies of the southern Exuma Cays on the eastern margin of the Great Bahama Bank show a complex history of late Pleistocene island construction. Pleistocene rocks include island core eolianites, overlain at island margins by fossil patch reefs and reef sands, which in turn are overlain by, and/or grade laterally into, talus breccia cones derived from the erosion of island core eolianite at paleo-seacliffs situated at approximately 5-6 m above present mean high tide. Laminated pedogenic calcrete widely caps Pleistocene rocks. Minor zones of penetrative subsurface calcretization, developed in association with root growth, occur along permeable horizons, including: contacts between talus units or crossbed sets, along tension joints, and (possibly) at the Pleistocene reef-eolianite contact. Among Pleistocene eolianite samples studied in thin-section, the relative proportions of ooids-intraclasts+grapestones-skeletal grains-peloids are approximately 48:39:6:7. Marginal to the Exuma Sound and on the Brigantine Cays, a greater proportion of ooids have peloidal nuclei and cortices with numerous laminae, which may reflect ooid derivation from shelf margin and broad platform interior regions that were characterized by high wave energy during ooid formation. Between these two areas, ooids are more commonly superficial and have cortices with few laminae and nuclei composed of subrounded micrite or pelmicrite intraclasts. Such ooid nuclei are most likely derived from storm erosion of partially cemented seafloor muds. Some skeletal-rich eolianite in this region may reflect local sediment input from platform margin reefs, or may be part of an older(?) stratigraphic unit.

Encounter with mesoscale eddies enhances survival to settlement in larval coral reef fishes

PubMed Central

Shulzitski, Kathryn; Sponaugle, Su; Hauff, Martha; Walter, Kristen D.; Cowen, Robert K.

2016-01-01

Oceanographic features, such as eddies and fronts, enhance and concentrate productivity, generating high-quality patches that dispersive marine larvae may encounter in the plankton. Although broad-scale movement of larvae associated with these features can be captured in biophysical models, direct evidence of processes influencing survival within them, and subsequent effects on population replenishment, are unknown. We sequentially sampled cohorts of coral reef fishes in the plankton and nearshore juvenile habitats in the Straits of Florida and used otolith microstructure analysis to compare growth and size-at-age of larvae collected inside and outside of mesoscale eddies to those that survived to settlement. Larval habitat altered patterns of growth and selective mortality: Thalassoma bifasciatum and Cryptotomus roseus that encountered eddies in the plankton grew faster than larvae outside of eddies and likely experienced higher survival to settlement. During warm periods, T. bifasciatum residing outside of eddies in the oligotrophic Florida Current experienced high mortality and only the slowest growers survived early larval life. Such slow growth is advantageous in nutrient poor habitats when warm temperatures increase metabolic demands but is insufficient for survival beyond the larval stage because only fast-growing larvae successfully settled to reefs. Because larvae arriving to the Straits of Florida from distant sources must spend long periods of time outside of eddies, our results indicate that they have a survival disadvantage. High productivity features such as eddies not only enhance the survival of pelagic larvae, but also potentially increase the contribution of locally spawned larvae to reef populations. PMID:27274058

Optical Algorithms at Satellite Wavelengths for Total Suspended Matter in Tropical Coastal Waters

PubMed Central

Ouillon, Sylvain; Douillet, Pascal; Petrenko, Anne; Neveux, Jacques; Dupouy, Cécile; Froidefond, Jean-Marie; Andréfouët, Serge; Muñoz-Caravaca, Alain

2008-01-01

Is it possible to derive accurately Total Suspended Matter concentration or its proxy, turbidity, from remote sensing data in tropical coastal lagoon waters? To investigate this question, hyperspectral remote sensing reflectance, turbidity and chlorophyll pigment concentration were measured in three coral reef lagoons. The three sites enabled us to get data over very diverse environments: oligotrophic and sediment-poor waters in the southwest lagoon of New Caledonia, eutrophic waters in the Cienfuegos Bay (Cuba), and sediment-rich waters in the Laucala Bay (Fiji). In this paper, optical algorithms for turbidity are presented per site based on 113 stations in New Caledonia, 24 stations in Cuba and 56 stations in Fiji. Empirical algorithms are tested at satellite wavebands useful to coastal applications. Global algorithms are also derived for the merged data set (193 stations). The performances of global and local regression algorithms are compared. The best one-band algorithms on all the measurements are obtained at 681 nm using either a polynomial or a power model. The best two-band algorithms are obtained with R412/R620, R443/R670 and R510/R681. Two three-band algorithms based on Rrs620.Rrs681/Rrs412 and Rrs620.Rrs681/Rrs510 also give fair regression statistics. Finally, we propose a global algorithm based on one or three bands: turbidity is first calculated from Rrs681 and then, if < 1 FTU, it is recalculated using an algorithm based on Rrs620.Rrs681/Rrs412. On our data set, this algorithm is suitable for the 0.2-25 FTU turbidity range and for the three sites sampled (mean bias: 3.6 %, rms: 35%, mean quadratic error: 1.4 FTU). This shows that defining global empirical turbidity algorithms in tropical coastal waters is at reach. PMID:27879929

CO32- concentration and pCO2 thresholds for calcification and dissolution on the Molokai reef flat, Hawaii

USGS Publications Warehouse

Yates, K.K.; Halley, R.B.

2006-01-01

The severity of the impact of elevated atmospheric pCO2 to coral reef ecosystems depends, in part, on how sea-water pCO2 affects the balance between calcification and dissolution of carbonate sediments. Presently, there are insufficient published data that relate concentrations of pCO 2 and CO32- to in situ rates of reef calcification in natural settings to accurately predict the impact of elevated atmospheric pCO2 on calcification and dissolution processes. Rates of net calcification and dissolution, CO32- concentrations, and pCO2 were measured, in situ, on patch reefs, bare sand, and coral rubble on the Molokai reef flat in Hawaii. Rates of calcification ranged from 0.03 to 2.30 mmol CaCO3 m-2 h-1 and dissolution ranged from -0.05 to -3.3 mmol CaCO3 m-2 h-1. Calcification and dissolution varied diurnally with net calcification primarily occurring during the day and net dissolution occurring at night. These data were used to calculate threshold values for pCO2 and CO32- at which rates of calcification and dissolution are equivalent. Results indicate that calcification and dissolution are linearly correlated with both CO32- and pCO2. Threshold pCO2 and CO32- values for individual substrate types showed considerable variation. The average pCO2 threshold value for all substrate types was 654??195 ??atm and ranged from 467 to 1003 ??atm. The average CO32- threshold value was 152??24 ??mol kg-1, ranging from 113 to 184 ??mol kg-1. Ambient seawater measurements of pCO2 and CO32- indicate that CO32- and pCO2 threshold values for all substrate types were both exceeded, simultaneously, 13% of the time at present day atmospheric pCO2 concentrations. It is predicted that atmospheric pCO2 will exceed the average pCO2 threshold value for calcification and dissolution on the Molokai reef flat by the year 2100.

Influence of land runoff on rates and agents of bioerosion of coral substrates.

PubMed

Hutchings, Pat; Peyrot-Clausade, Mireille; Osnorno, Alicia

2005-01-01

Annually large volumes of fresh water laden with sediment are washed down the Daintree River in North Queensland into the Great Barrier Reef lagoon. To investigate the effects of land runoff on bioerosion, samples of recently killed colonies of Porites were laid at 6 sites on a cross shelf transect from Snapper Island at the entrance to the river to Osprey Reef, approximately 328 km from the river mouth out in the Coral Sea. Rates and agents of bioerosion were determined over 4 years and inshore sites exhibited significantly lower rates of total bioerosion than the other sites. Offshore sites experienced high rates of bioerosion primarily due to grazing and internal bioerosion by macroborers such as sponges and bivalves was also important at some of these sites. Inshore sites were covered in heavy layers of silt which inhibited colonization and growth of microborers, primarily algae. This resulted in lower levels of grazing than at offshore sites. However the activity of macroborers (primarily sponges and bivalves) was often high at these sites. The macroboring communities differed between sites and over time and it is hypothesised that these site differences were due to different levels of terrestrial runoff. These results are compared with those from French Polynesia where contaminated terrestrial runoff greatly influenced rates and agents of bioerosion. However other factors such as overfishing may also play an important role in some locations.

The Great Tumaco, Colombia earthquake of 12 December 1979

USGS Publications Warehouse

Herd, D.G.; Youd, T.L.; Meyer, H.; Arango, C.J.L.; Person, W.J.; Mendoza, C.

1981-01-01

Southwestern Colombia and northern Ecuador were shaken by a shallow-focus earthquake on 12 December 1979. The magnitude 8 shock, located near Tumaco, Colombia, was the largest in northwestern South America since 1942 and had been forecast to fill a seismic gap. Thrust faulting occurred on a 280- by 130-kilometer rectangular patch of a subduction zone that dips east beneath the Pacific coast of Colombia. A 200-kilometer stretch of the coast tectonically subsided as much as 1.6 meters; uplift occurred offshore on the continental slope. A tsunami swept inland immediately after the earthquake. Ground shaking (intensity VI to IX) caused many buildings to collapse and generated liquefaction in sand fills and in Holocene beach, lagoonal, and fluvial deposits.

Interaction between inorganic nutrients and organic matter in controlling coral reef communities in Glovers Reef Belize.

PubMed

McClanahan, T R; Steneck, R S; Pietri, D; Cokos, B; Jones, S

2005-05-01

We studied the responses of algae, corals, and small fish to elevated inorganic fertilizer, organic matter, and their combination over a 49-day summer period in cages that simulated the coral reef in the remote Glovers reef atoll, Belize. The addition of organic matter reduced while fertilization had no effect on the numbers of herbivorous damsel and parrotfishes. All measures of algal biomass were influenced by fertilization. The combined inorganic and organic enrichment produced the highest algal biomass, which is most likely due to the combined effect of higher nutrients and lower herbivory. The cover of turf and total algae were influenced by all treatments and their interactions and most strongly and positively influenced by fertilization followed by organic matter and the combination of organic matter and inorganic fertilizer. The inorganic and combined treatments were both dominated by two turf algae, Enteromorpha prolifera and Digenia simplex, while the nonfertilized treatments were dominated by brown frondose algae Lobophora variegata, Padina sanctae, and Dictyota cervicornis. The organic matter treatment had greater cover of P. sanctae and D. cervicornis than the untreated control, which was dominated by Lobophora variegata, also the dominant algae on the nearby patch reefs. Crustose corallines grew slowly ( approximately 2.5 mm/49 days) and were not influenced by the treatments when grown on vertical surfaces but decreased on horizontal coral plates in the combined organic matter and fertilization treatment. No mortality occurred for the two coral species that were added to the cages. Porites furcata darkened in the fertilized cages while there was a mix of paling and darkening for a small amount of the coral tissue of Diploria labyrinthiformes. Inorganic fertilization stimulates small filamentous turf algae and Symbiodinium living in coral but inhibits brown frondose algae. Organic matter inhibits small herbivorous fish, L. variegata, and encrusting coralline algae when growing on horizontal surfaces.

New Prespective Paleogeography of East Java Basin; Implicationrespond to Oil and Gas Eksploration at Kujung Formation Carbonate Reservoar

NASA Astrophysics Data System (ADS)

Aprilana, C.; Premonowati; S, Hanif I.; Choirotunnisa; Shirly, A.; Utama, M. K.; Sinulingga, Y. R.; Syafitra, F.

2018-03-01

Paleogeography is one of critical points that always less considered by explorationist in the world. Almost all of the consideration is focused on trapping mechanism. Paleogeography is guidance in understanding both of physical and chemical of rock characteristic which will correlate with its depositional environment. Integration of various geological and geophysical data such as; tectonic, structural geology, stratigraphy, lithology, and biostratigraphy will lead us to a better understanding of rock characteristics. Six paleogeographic interpretations was made consist of; Early Tertiary (P5-56-55 ma), Middle Eocene (P14-41 ma), Late Oiligocene (P22-25.5 ma), Early Miocene (N7-16.5 ma), Middle Miocene (N9-14.5 ma), and Pleistocene (NN19-1.5 ma). That six paleogeographic interpretations are assumed represent the paleogeographic evolution of East Java Basin time after time. In Middle Eocene time, it would be more than hundred possibilities regarding the location where the formation deposited. This would be controlled by the existence of some local structural paleohighs and horsts which oriented NW-SE followed by their own sedimentary transportation path. With assumption that hydrocarbon generation was occurred in 15 Ma and the depth of maturation window lies on about 2,500 m depth. Therefore, the possibility of source rock maturation is high, due to almost of the clastics sediment of Ngimbang deposited into the series of grabens. The Kujung reef types simplified defines and categorize into; 1) Patch Reef 2) Berrier Reef 3) Pinnacle Reef Over Isolated Reef. Kujung Carbonates were deposited in Early Miocene when regional transgression occurred. The depositional environments were dominated by shallow marine littoral-sublittoral. Generally, the reservoir quality of this Kujung Carbonate shows fair to good quality, in range7-32% porosity, and 1-1400 mD permeability (internal SKK Migas data).

Characteristics of drift pumice from New Caledonia beaches

NASA Astrophysics Data System (ADS)

Nicholson, Kirsten Ngaire; Stewart, Ariel

2016-12-01

Siliceous drift pumice was collected from a total of 40 beaches around the main island of New Caledonia, Southwest Pacific, in order to determine its provenance. New Caledonia is enclosed by a barrier reef lagoon whose 2008 designation as a UNESCO World Heritage Site brought attention to the environmental degradation caused by a century of open cast nickel mining. The frequent, voluminous pumice eruptions in the Southwest Pacific provide ample source material that is somewhat durable, highly transportable in water, and easy to collect and analyze. Geochemical and mineralogical analyses were used to identify the source of the pumice in order to map the transport vector across the open ocean and into the lagoon. Drift pumice was sampled during 2008 and 2010. The mineral assemblage of the pumice was consistently calcic plagioclase, clinopyroxene, orthopyroxene, and opaque minerals. All of the pumice was of fairly uniform geochemistry: low in mafic elements, low in alkalis, with LILE enriched compared to HFSE, and negative Eu, Ti, and Zr anomalies. The pumice is predominately dacitic and tholeiitic. This geochemical signature was consistent with published data from the Tonga arc, which is further supported by the mineralogy. With the exception of two samples (which probably came from either the Kermadec arc or Vanuatu) all of the pumice comes from the Tonga arc. The samples from 2008 are consistent with pumice erupted from Metis Shoal in 2006, and the majority of 2010 samples are consistent with pumice erupted from an unnamed volcano (0403-091) that erupted in 2001.

Microfacies and diagenesis of the reefal limestone, Callovian Tuwaiq Mountain Limestone Formation, central Saudi Arabia

NASA Astrophysics Data System (ADS)

EL-Sorogy, Abdelbaset S.; Almadani, Sattam A.; Al-Dabbagh, Mohammad E.

2016-03-01

In order to document the microfacies and diagenesis of the reefal limestone in the uppermost part of the Callovian Tuwaiq Mountain Limestone Formation at Khashm Al-Qaddiyah area, central Saudi Arabia, scleractinian corals and rock samples were collected and thin sections were prepared. Coral framestone, coral floatstone, pelloidal packstone, bioclastic packstone, bioclastic wacke/packstone, algal wackestone and bioclastic foraminiferal wacke/packstone were the recorded microfacies types. Cementation, recrystallization, silicification and dolomitization are the main diagenetic alterations affected the aragonitic skeletons of scleractinian corals. All coral skeletons were recrystallized, while some ones were dolomitized and silicified. Microfacies types, as well as the fossil content of sclearctinian corals, bivalves, gastropods, brachiopods and foraminifera indicated a deposition in environments ranging from shelf lagoon with open circulation in quiet water below wave base to shallow reef flank and organic build up for the uppermost reefal part of the Tuwaiq Formation in the study area.

The dynamics of coastal models

USGS Publications Warehouse

Hearn, Clifford J.

2008-01-01

Coastal basins are defined as estuaries, lagoons, and embayments. This book deals with the science of coastal basins using simple models, many of which are presented in either analytical form or Microsoft Excel or MATLAB. The book introduces simple hydrodynamics and its applications, from the use of simple box and one-dimensional models to flow over coral reefs. The book also emphasizes models as a scientific tool in our understanding of coasts, and introduces the value of the most modern flexible mesh combined wave-current models. Examples from shallow basins around the world illustrate the wonders of the scientific method and the power of simple dynamics. This book is ideal for use as an advanced textbook for graduate students and as an introduction to the topic for researchers, especially those from other fields of science needing a basic understanding of the basic ideas of the dynamics of coastal basins.

Metacystis borrori n. sp. (Ciliophora: Metacystidae) on the seagrass Thalassia testudinum.

PubMed

Aladro-Lubel, M A Antonieta; Martinez-Murillo, M A Esther

2003-01-01

A new epibiontic ciliate of the genus Metacystis is described on the seagrass Thalassia testudinum of the coral reef lagoons of Veracruz, Mexico. The ciliate was studied in living and stained specimens and under the scanning electron microscope. The cell body (10-35 x 10-18 microm in vivo) is transversely annulated (4-6 rings). The somatic ciliature consists of 22-30 longitudinal kineties, and patterned as 5-7 transverse kineties. The circumoral kinety is composed of kinetosomes closely spaced. The macronucleus diameter measures about 3-7 microm. The lorica (18-61 x 11-26 microm) has the posterior end round to conical or irregular with mucoid filaments. This prostomatid colonizes both natural and artificial substrates placed in an aquarium. Metacystis borrori n. sp. is a species that forms part of the ciliate community on Thalassia testudinum with a temperature range of 21-26 degrees C and a salinity of 32-40 per thousand.

Direct contribution of the seagrass Thalassia testudinum to lime mud production.

PubMed

Enríquez, Susana; Schubert, Nadine

2014-05-22

Seagrass beds contribute to oceanic carbonate lime mud production by providing a habitat for a wide variety of calcifying organisms and acting as efficient sediment traps. Here we provide evidence for the direct implication of Thalassia testudinum in the precipitation of aragonite needles. The crystals are located internally in the cell walls, and as external deposits on the blade, and are similar in size and shape to the aragonite needles reported for modern tropical carbonate factories. Seagrass calcification is a biological, light-enhanced process controlled by the leaf, and estimates of seagrass annual carbonate production in a Caribbean reef lagoon are as significant as values reported for Halimeda incrassata. Thus, we conclude that seagrass calcification is another biological source for the aragonite lime mud deposits found in tropical banks, and that tropical seagrass habitats may play a more important role in the oceanic carbon cycle than previously considered.

Direct contribution of the seagrass Thalassia testudinum to lime mud production

NASA Astrophysics Data System (ADS)

Enríquez, Susana; Schubert, Nadine

2014-05-01

Seagrass beds contribute to oceanic carbonate lime mud production by providing a habitat for a wide variety of calcifying organisms and acting as efficient sediment traps. Here we provide evidence for the direct implication of Thalassia testudinum in the precipitation of aragonite needles. The crystals are located internally in the cell walls, and as external deposits on the blade, and are similar in size and shape to the aragonite needles reported for modern tropical carbonate factories. Seagrass calcification is a biological, light-enhanced process controlled by the leaf, and estimates of seagrass annual carbonate production in a Caribbean reef lagoon are as significant as values reported for Halimeda incrassata. Thus, we conclude that seagrass calcification is another biological source for the aragonite lime mud deposits found in tropical banks, and that tropical seagrass habitats may play a more important role in the oceanic carbon cycle than previously considered.

Direct contribution of the seagrass Thalassia testudinum to lime mud production

PubMed Central

Enríquez, Susana; Schubert, Nadine

2014-01-01

Seagrass beds contribute to oceanic carbonate lime mud production by providing a habitat for a wide variety of calcifying organisms and acting as efficient sediment traps. Here we provide evidence for the direct implication of Thalassia testudinum in the precipitation of aragonite needles. The crystals are located internally in the cell walls, and as external deposits on the blade, and are similar in size and shape to the aragonite needles reported for modern tropical carbonate factories. Seagrass calcification is a biological, light-enhanced process controlled by the leaf, and estimates of seagrass annual carbonate production in a Caribbean reef lagoon are as significant as values reported for Halimeda incrassata. Thus, we conclude that seagrass calcification is another biological source for the aragonite lime mud deposits found in tropical banks, and that tropical seagrass habitats may play a more important role in the oceanic carbon cycle than previously considered. PMID:24848374

The Gulf of Carpentaria heated Torres Strait and the Northern Great Barrier Reef during the 2016 mass coral bleaching event

NASA Astrophysics Data System (ADS)

Wolanski, E.; Andutta, F.; Deleersnijder, E.; Li, Y.; Thomas, C. J.

2017-07-01

The 2015/16 ENSO event increased the temperature of waters surrounding northeast Australia to above 30 °C, with large patches of water reaching 32 °C, for over two months, which led to severe bleaching of corals of the Northern Great Barrier Reef (NGBR). This study provides evidence gained from remote-sensing data, oceanographic data and oceanographic modeling, that three factors caused this excessive heating, namely: 1) the shutdown of the North Queensland Coastal Current, which would otherwise have flushed and cooled the Northern Coral Sea and the NGBR through tidal mixing 2) the advection of warm (>30 °C) water from the Gulf of Carpentaria eastward through Torres Strait and then southward over the NGBR continental shelf, and 3) presumably local solar heating. The eastward flux of this warm water through Torres Strait was driven by a mean sea level difference on either side of the strait that in turn was controlled by the wind, which also generated the southward advection of this warm water onto the NGBR shelf. On the NGBR shelf, the residence time of this warm water was longer inshore than offshore, and this may explain the observed cross-shelf gradient of coral bleaching intensity. The fate of the Great Barrier Reef is thus controlled by the oceanography of surrounding seas.

Characterization of Anopheles darlingi (Diptera: Culicidae) larval habitats in Belize, Central America

NASA Technical Reports Server (NTRS)

Manguin, S.; Roberts, D. R.; Andre, R. G.; Rejmankova, E.; Hakre, S.

1996-01-01

Surveys for larvae of Anopheles darlingi Root were conducted in April, May, and August 1994 in riverine habitats of central Belize (Cayo and Belize districts). An. darlingi was present during both the dry and wet seasons. Larvae were encountered most frequently in patches of floating debris along river margins. The floating mats were often formed by bamboo hanging over the banks and dense submersed bamboo roots. Larvae were found less frequently in lake margins, small lagoons, and ground pools with submersed roots and patches of floating leaves or vegetation. In addition to their association with floating debris, larvae of An. darlingi were associated positively with shade and submersed plants in riverine environments. Samples from river habitats showed the larvae of Anopheles albimanus Wiedemann to be strongly associated with sun-exposed sites containing green or blue-green algae. Unlike An. darlingi, An. albimanus was an ubiquitous mosquito, the immatures of which occurred in a wide variety of riverine and nonriverine aquatic habitats. Based on published reports and our experience, the association of An. darlingi with river systems was verified, and its distribution in Central America and Mexico was mapped.

Coral color and depth drive symbiosis ecology of Montipora capitata in Kāne`ohe Bay, O`ahu, Hawai`i

NASA Astrophysics Data System (ADS)

Innis, T.; Cunning, R.; Ritson-Williams, R.; Wall, C. B.; Gates, R. D.

2018-06-01

Scleractinian corals form symbioses with diverse photosynthetic dinoflagellates (genus Symbiodinium) that confer varying levels of performance and stress tolerance to their hosts. Variation in thermal stress susceptibility (i.e., bleaching) among conspecific corals is linked to variability in symbiont community composition, yet factors driving heterogeneous symbiont associations within a population are poorly understood. To investigate potential drivers, we characterized Symbiodinium communities in Montipora capitata ( N = 707 colonies) across the biophysical regions, reef types, and depth range of Kāne`ohe Bay (Hawai`i, USA), where this dominant reef-builder associates with Symbiodinium spp. in clade C (C31) and/or D ( S. glynnii), and occurs as brown and orange color morphs. The distribution of these traits was primarily influenced by depth: orange, D-dominated colonies were more prevalent in shallow, high light environments (< 2 m), whereas brown, C-dominated colonies were more prevalent with increasing depth and light attenuation. Though either color morph could be dominated by either symbiont, brown colonies were almost exclusively C-dominated, while orange colonies were more likely to be D-dominated above 4.3 m, and C-dominated below, revealing a significant interaction between color morph and symbiosis ecology. The distribution of orange, D-dominated colonies extended deeper on patch reefs, where light penetrates deeper, compared to the more turbid, fringing reefs, further supporting light as the driver of these patterns. This work reveals that symbiont community variability may arise either from holobiont phenotypic plasticity or differential survival across light gradients, with implications for predicting coral bleaching responses and informing management applications such as selective breeding of robust corals.

Influence of prey body characteristics and performance on predator selection.

PubMed

Holmes, Thomas H; McCormick, Mark I

2009-03-01

At the time of settlement to the reef environment, coral reef fishes differ in a number of characteristics that may influence their survival during a predatory encounter. This study investigated the selective nature of predation by both a multi-species predator pool, and a single common predator (Pseudochromis fuscus), on the reef fish, Pomacentrus amboinensis. The study focused on the early post-settlement period of P. amboinensis, when mortality, and hence selection, is known to be highest. Correlations between nine different measures of body condition/performance were examined at the time of settlement, in order to elucidate the relationships between different traits. Single-predator (P. fuscus) choice trials were conducted in 57.4-l aquaria with respect to three different prey characteristics [standard length (SL), body weight and burst swimming speed], whilst multi-species trials were conducted on open patch reefs, manipulating prey body weight only. Relationships between the nine measures of condition/performance were generally poor, with the strongest correlations occurring between the morphological measures and within the performance measures. During aquaria trials, P. fuscus was found to be selective with respect to prey SL only, with larger individuals being selected significantly more often. Multi-species predator communities, however, were selective with respect to prey body weight, with heavier individuals being selected significantly more often than their lighter counterparts. Our results suggest that under controlled conditions, body length may be the most important prey characteristic influencing prey survival during predatory encounters with P. fuscus. In such cases, larger prey size may actually be a distinct disadvantage to survival. However, these relationships appear to be more complex under natural conditions, where the expression of prey characteristics, the selectivity fields of a number of different predators, their relative abundance, and the action of external environmental characteristics, may all influence which individuals survive.

Stormy seas in Sagittarius

NASA Image and Video Library

2017-12-08

Some of the most breathtaking views in the Universe are created by nebulae — hot, glowing clouds of gas. This new NASA/ESA Hubble Space Telescope image shows the centre of the Lagoon Nebula, an object with a deceptively tranquil name. The region is filled with intense winds from hot stars, churning funnels of gas, and energetic star formation, all embedded within an intricate haze of gas and pitch-dark dust. Nebulae are often named based on their key characteristics — particularly beautiful examples include the Ring Nebula (heic1310), the Horsehead Nebula (heic1307) and the Butterfly Nebula (heic0910). This new NASA/ESA Hubble Space Telescope image shows the centre of the Lagoon Nebula, otherwise known as Messier 8, in the constellation of Sagittarius (The Archer). The inspiration for this nebula’s name may not be immediately obvious — this is because the image captures only the very heart of the nebula. The Lagoon Nebula’s name becomes much clearer in a wider field view (opo0417i) when the broad, lagoon-shaped dust lane that crosses the glowing gas of the nebula can be made out. Another clear difference between this new image and others is that this image combines both infrared and optical light rather than being purely optical(heic1015). Infrared light cuts through thick, obscuring patches of dust and gas, revealing the more intricate structures underneath and producing a completely different landscape [1]. However, even in visible light, the tranquil name remains misleading as the region is packed full of violent phenomena. The bright star embedded in dark clouds at the centre of this image is known as Herschel 36. This star is responsible for sculpting the surrounding cloud, stripping away material and influencing its shape. Herschel 36 is the main source of ionising radiation [2] for this part of the Lagoon Nebula. This central part of the Lagoon Nebula contains two main structures of gas and dust connected by wispy twisters, visible in the middle third of this image (opo9638). These features are quite similar to their namesakes on Earth — they are thought to be wrapped up into their funnel-like shapes by temperature differences between the hot surface and cold interior of the clouds. The nebula is also actively forming new stars, and energetic winds from these newborns may contribute to creating the twisters. This image combines images taken using optical and infrared light gathered by Hubble’s Wide Field Planetary Camera 2. Credit: NASA, ESA, J. Trauger (Jet Propulson Laboratory) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

A palynostratigraphic approach to the SW Anatolian molasse basin: Kale-Tavas molasse and Denizli molasse

NASA Astrophysics Data System (ADS)

Akgün, Funda; Sözbilir, Hasan

The study, explains stratigraphy of the Oligo-Miocene molasse around the Denizli province (SW Anatolia), based on the palynology which is also supported by the detailed mapping and correlation of the measured sections from the coal-bearing sequences of the molasse deposits. For this purpose, two huge depressions named as the Kale-Tavas molasse and Denizli molasse basins were examined. The Kale-Tavas molasse deposits has a basal unconformity with the underlying pre-Oligocene basement and begins with the Chattian Karadere and Mortuma formations which are covered unconformably by the Aquitanian Yenidere formation. An angular unconformity between the Chattian and the Burdigalian is only observed in the middle part of the basin, around Kale. In the Tavas section, the Aquitanian and the Burdigalian are absent. The Denizli molasse is characterized by Chattian-Aquitanian sequence consisting of distinctive sedimentary facies, alluvial fan and deltaic-shallow marine deposits with carbonate patch reefs. Palynostratigraphic studies, which have given the Chattian age, have been carried out from the coal lenses of alluvial fan and delta plain deposits. In addition to the palynological determinations, coral and foraminiferal content of the carbonate patch reefs which rest conformably on the coal-bearing sequences have yielded the Chattian-Aquitanian age. Two different palynomorph associations have been determined from the molasse deposits. The first palynomorph association which is established in the samples from the Sağdere and Mortuma formations, corresponds to the Chattian age, whilst the second is of the Aquitanian age. The Late Oligocene-Early Miocene which is claimed as the time of N-S-extensional tectonics in western Turkey, is related to the depositional time of the molasse sequences in the study area. Thus, the molasse is older than the basal deposits of the Gediz and Büyük Menderes grabens.

Marked annual coral bleaching resilience of an inshore patch reef in the Florida Keys: A nugget of hope, aberrance, or last man standing?

NASA Astrophysics Data System (ADS)

Gintert, Brooke E.; Manzello, Derek P.; Enochs, Ian C.; Kolodziej, Graham; Carlton, Renée; Gleason, Arthur C. R.; Gracias, Nuno

2018-06-01

Annual coral bleaching events, which are predicted to occur as early as the next decade in the Florida Keys, are expected to cause catastrophic coral mortality. Despite this, there is little field data on how Caribbean coral communities respond to annual thermal stress events. At Cheeca Rocks, an inshore patch reef near Islamorada, FL, the condition of 4234 coral colonies was followed over 2 yr of subsequent bleaching in 2014 and 2015, the two hottest summers on record for the Florida Keys. In 2014, this site experienced 7.7 degree heating weeks (DHW) and as a result 38.0% of corals bleached and an additional 36.6% were pale or partially bleached. In situ temperatures in summer of 2015 were even warmer, with the site experiencing 9.5 DHW. Despite the increased thermal stress in 2015, only 12.1% of corals were bleached in 2015, which was 3.1 times less than 2014. Partial mortality dropped from 17.6% of surveyed corals to 4.3% between 2014 and 2015, and total colony mortality declined from 3.4 to 1.9% between years. Total colony mortality was low over both years of coral bleaching with 94.7% of colonies surviving from 2014 to 2016. The reduction in bleaching severity and coral mortality associated with a second stronger thermal anomaly provides evidence that the response of Caribbean coral communities to annual bleaching is not strictly temperature dose dependent and that acclimatization responses may be possible even with short recovery periods. Whether the results from Cheeca Rocks represent an aberration or a true resilience potential is the subject of ongoing research.

Submarine groundwater discharge into typical tropical lagoons: A case study in eastern Hainan Island, China

NASA Astrophysics Data System (ADS)

Wang, Xilong; Du, Jinzhou

2016-11-01

Assessing submarine groundwater discharge (SGD) into lagoons and bays can be helpful to understand biogeochemical processes, especially nutrient dynamics. In the present paper, radium (Ra) isotopes were used to quantify SGD in two typical tropical lagoons (Laoye Lagoon (LY Lagoon) and Xiaohai Lagoon (XH Lagoon)) of eastern Hainan Island, China. The Ra mass balance model provided evidence that SGD plays an important role in the hydrology of the LY Lagoon and the XH Lagoon, delivering average SGD fluxes of 1.7 × 106 (94 L m-2 d-1) and 1.8 × 106 (41 L m-2 d-1) m3 d-1, respectively. Tidal pumping was one of the important driving forces for SGD fluxes in the LY and the XH Lagoons. Tidal-driven SGD into the tidal channels of both lagoons can account for approximately 10% of the total SGD flux into the lagoons. In addition, the dissolved inorganic nutrient budgets were reassessed in the LY Lagoon and the XH Lagoon, which showed that SGD was the major source of nutrients entering the LY Lagoon and that the LY Lagoon behaved as a source for dissolved inorganic nitrogen (DIN) and dissolved inorganic phosphorus (DIP) and as a sink for dissolved silicate (DSi). Nutrient loads in the XH Lagoon were mainly derived from riverine inputs and SGD, and the XH Lagoon behaved as a source for DIP, but a sink for DIN and DSi.

KSC00pp1264

NASA Image and Video Library

2000-09-08

KENNEDY SPACE CENTER, Fla. -- Looking like a lighted taper against a cloud-streaked sky, Space Shuttle Atlantis belches a column of smoke as it blasts into space. In the foreground are patches of water and marsh between the Mosquito Lagoon on the north and Banana Creek on the south. In the background is the Atlantic Ocean. The perfect on-time liftoff of Atlantis occurred at 8:45:47 a.m. EDT. On the 11-day mission to the International Space Station, the seven-member crew will perform support tasks on orbit, transfer supplies and prepare the living quarters in the newly arrived Zvezda Service Module. The first long-duration crew, dubbed “Expedition One,” is due to arrive at the Station in late fall. Landing of Atlantis is targeted for 4:45 a.m. EDT on Sept. 19

KSC-00pp1264

NASA Image and Video Library

2000-09-08

KENNEDY SPACE CENTER, Fla. -- Looking like a lighted taper against a cloud-streaked sky, Space Shuttle Atlantis belches a column of smoke as it blasts into space. In the foreground are patches of water and marsh between the Mosquito Lagoon on the north and Banana Creek on the south. In the background is the Atlantic Ocean. The perfect on-time liftoff of Atlantis occurred at 8:45:47 a.m. EDT. On the 11-day mission to the International Space Station, the seven-member crew will perform support tasks on orbit, transfer supplies and prepare the living quarters in the newly arrived Zvezda Service Module. The first long-duration crew, dubbed “Expedition One,” is due to arrive at the Station in late fall. Landing of Atlantis is targeted for 4:45 a.m. EDT on Sept. 19

Hubble reveals heart of Lagoon Nebula

NASA Image and Video Library

2010-09-22

Image release date September 22, 2010 To view a video of this image go here: www.flickr.com/photos/gsfc/5014452203 Caption: A spectacular new NASA/ESA Hubble Space Telescope image reveals the heart of the Lagoon Nebula. Seen as a massive cloud of glowing dust and gas, bombarded by the energetic radiation of new stars, this placid name hides a dramatic reality. The Advanced Camera for Surveys (ACS) on the NASA/ESA Hubble Space Telescope has captured a dramatic view of gas and dust sculpted by intense radiation from hot young stars deep in the heart of the Lagoon Nebula (Messier 8). This spectacular object is named after the wide, lagoon-shaped dust lane that crosses the glowing gas of the nebula. This structure is prominent in wide-field images, but cannot be seen in this close-up. However the strange billowing shapes and sandy texture visible in this image make the Lagoon Nebula’s watery name eerily appropriate from this viewpoint too. Located four to five thousand light-years away, in the constellation of Sagittarius (the Archer), Messier 8 is a huge region of star birth that stretches across one hundred light-years. Clouds of hydrogen gas are slowly collapsing to form new stars, whose bright ultraviolet rays then light up the surrounding gas in a distinctive shade of red. The wispy tendrils and beach-like features of the nebula are not caused by the ebb and flow of tides, but rather by ultraviolet radiation’s ability to erode and disperse the gas and dust into the distinctive shapes that we see. In recent years astronomers probing the secrets of the Lagoon Nebula have found the first unambiguous proof that star formation by accretion of matter from the gas cloud is ongoing in this region. Young stars that are still surrounded by an accretion disc occasionally shoot out long tendrils of matter from their poles. Several examples of these jets, known as Herbig-Haro objects, have been found in this nebula in the last five years, providing strong support for astronomers’ theories about star formation in such hydrogen-rich regions. The Lagoon Nebula is faintly visible to the naked eye on dark nights as a small patch of grey in the heart of the Milky Way. Without a telescope, the nebula looks underwhelming because human eyes are unable to distinguish clearly between colours at low light levels. Charles Messier, the 18th century French astronomer, observed the nebula and included it in his famous astronomical catalogue, from which the nebula’s alternative name comes. But his relatively small refracting telescope would only have hinted at the dramatic structures and colours now visible thanks to Hubble. The Hubble Space Telescope is a project of international cooperation between ESA and NASA. Image credit: NASA, ESA NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram To learn more about the Hubble Space Telescope go here: www.nasa.gov/mission_pages/hubble/main/index.html

Alternating seismic uplift and subsidence in the late Holocene at Madang, Papua New Guinea: Evidence from raised reefs

USGS Publications Warehouse

Tudhope, A.W.; Buddemeier, R.W.; Chilcott, C.P.; Berryman, K.R.; Fautin, D.G.; Jebb, M.; Lipps, J.H.; Pearce, R.G.; Scoffin, T.P.; Shimmield, G.B.

2000-01-01

Well-preserved mid-late Holocene coral reefs are exposed in low coastal cliffs in the vicinity of the Madang lagoon on the north coast of Papua New Guinea. Results from U/Th and 14C dating of corals, surveying, and field mapping indicate several major changes in relative sea level over this period. Specifically, there is evidence for a relative sea level fall of ??? 4.5 m about 3000 calendar years B.P., followed by relative sea level rises of ???1.5 m about 2400 calendar years B.P. and ??? 0.5 m about 1200 calendar years B.P. and a subsequent relative sea level fall of ??? 3 m some time in the past 1000 years. Since regional eustatic sea levels are believed to have been dropping gradually over this time frame, these observed changes in relative sea level are interpreted as reflecting alternating tectonic uplift and subsidence. Furthermore, the detailed structure and age relationships of the coral deposits indicate that both uplift and subsidence occurred rapidly, most probably as coseismic events with vertical displacements of 0.5 to 4.5 m. These events may be related to rupture on NW-SE trending reverse faults which have been mapped in the nearby Adelbert Range and possibly on NE trending cross faults which have been inferred from seismicity. This interpretation implies a much greater degree of tectonic instability and potential seismic hazard in the region than previously recognized, although the inferred coseismic vertical displacements are shown to be consistent with present-day local seismicity. In a broader context, the study illustrates how detailed analysis of vertical changes in coral reef structure and assemblages may be used as a sensitive indicator of changing relative sea level, capable of resolving century timescale events and reversals. Copyright 2000 by the American Geophysical Union.

The fate of Mediterranean lagoons under climate change

NASA Astrophysics Data System (ADS)

Umgiesser, Georg; Ferrarin, Christian; Cucco, Andrea; De Pascalis, Francesca; Ghezzo, Michol; Bellafiore, Debora; Bajo, Marco

2014-05-01

A numerical model (SHYFEM) has been applied to 10 Mediterranean lagoons and a comparison study between the lagoons has been carried out. The lagoons are the lagoons of Venice, Marano-Grado, Varano and Lesina in the Adriatic Sea, the Taranto basin in the Ionian Sea, the Cabras lagoon in Sardinia, and the lagoons of Ganzirri and Faro in Sicily, the Mar Menor in Spain and the Nador lagoon in Morocco. These lagoons give a representative picture of the lagoons situated around the Mediterranean basin. The lagoons range from a leaky type of lagoons to a choked type. The number of inlets ranges from just one in the Nador lagoon to 6 in the case of the Marano-Grado lagoons. Tidal range is from nano-tidal to micro-tidal. The depth ranges from an average depth of 1 m to up to 40 meters. The model is a finite element model, especially suited to shallow water basins with complicated geometric and morphologic variations. The model can compute the basic hydrodynamics, dispersion of tracers, temperature and salinity evolution, sediment transport and ecological parameters. Building on an earlier study that focused on the classification of Mediterranean lagoons based on hydrodynamics, exchange rates and renewal time, this study is concerned with the changes in physical parameters under climate change. Data from IPCC has been used to simulate the changes in renewal time, salinity and temperature of all lagoons, with respect to the control simulation. Whenever possible downscaled data for the Mediterranean basin have been used. Sea level rise scenarios are taken from the last IPCC report. The model has been applied in its 3D version and the chosen setup allows a comparison between results in the different lagoons. Results indicate that the differences of renewal time between all studied lagoons become smaller. This means that leaky lagoons become less leaky and choked lagoons less choked. What concerns temperature and salinity, changes occurring in the sea are amplified inside lagoons. All lagoons show an increase of temperature higher than the one found outside in the sea. Salinity changes are also enhanced. This study shows how numerical modeling can be a useful tool to study the hydrodynamic changes forecasted to happen in transitional water bodies like lagoons.

A coupled wave-hydrodynamic model of an atoll with high friction: Mechanisms for flow, connectivity, and ecological implications

NASA Astrophysics Data System (ADS)

Rogers, Justin S.; Monismith, Stephen G.; Fringer, Oliver B.; Koweek, David A.; Dunbar, Robert B.

2017-02-01

We present a hydrodynamic analysis of an atoll system from modeling simulations using a coupled wave and three-dimensional hydrodynamic model (COAWST) applied to Palmyra Atoll in the Central Pacific. This is the first time the vortex force formalism has been applied in a highly frictional reef environment. The model results agree well with field observations considering the model complexity in terms of bathymetry, bottom roughness, and forcing (waves, wind, metrological, tides, regional boundary conditions), and open boundary conditions. At the atoll scale, strong regional flows create flow separation and a well-defined wake, similar to 2D flow past a cylinder. Circulation within the atoll is typically forced by waves and tides, with strong waves from the north driving flow from north to south across the atoll, and from east to west through the lagoon system. Bottom stress is significant for depths less than about 60 m, and in addition to the model bathymetry, is important for correct representation of flow in the model. Connectivity within the atoll system shows that the general trends follow the mean flow paths. However, some connectivity exists between all regions of the atoll system due to nonlinear processes such as eddies and tidal phasing. Moderate wave stress, short travel time (days since entering the reef system), and low temperature appear to be the most ideal conditions for high coral cover at this site.

A coupled wave-hydrodynamic model of a highly frictional atoll reef system: mechanisms for flow, connectivity, and ecological implications

NASA Astrophysics Data System (ADS)

Rogers, J.; Monismith, S. G.; Fringer, O. B.; Koweek, D.; Dunbar, R. B.

2016-12-01

We present a hydrodynamic analysis of an atoll system from modeling simulations using a coupled wave and three-dimensional hydrodynamic model (COAWST) applied to Palmyra Atoll in the Central Pacific. This is the first time the vortex force formalism has been applied in a highly frictional reef environment. The model results agree well with field observations considering the model complexity in terms of bathymetry, bottom roughness, and forcing (waves, wind, metrological, tides, regional boundary conditions), and open boundary conditions. At the atoll scale, strong regional flows create flow separation and a well-defined wake, similar to 2D flow past a cylinder. Circulation within the atoll is typically forced by waves and tides, with strong waves from the north driving flow from north to south across the atoll, and from east to west through the lagoon system. Bottom stress is significant for depths less than about 60 m, and in addition to the model bathymetry, is important for correct representation of flow in the model. Connectivity within the atoll system shows that the general trends follow the mean flow paths. However, some connectivity exists between all regions of the atoll system due to nonlinear processes such as eddies and tidal phasing. While high mean flow and travel time less than 20 hours appears to differentiate very productive coral regions, low temperature and moderate wave stress appear to be the most ideal conditions for high coral cover on Palmyra.

Multilocus adaptation associated with heat resistance in reef-building corals.

PubMed

Bay, Rachael A; Palumbi, Stephen R

2014-12-15

The evolution of tolerance to future climate change depends on the standing stock of genetic variation for resistance to climate-related impacts, but genes contributing to climate tolerance in wild populations are poorly described in number and effect. Physiology and gene expression patterns have shown that corals living in naturally high-temperature microclimates are more resistant to bleaching because of both acclimation and fixed effects, including adaptation. To search for potential genetic correlates of these fixed effects, we genotyped 15,399 single nucleotide polymorphisms (SNPs) in 23 individual tabletop corals, Acropora hyacinthus, within a natural temperature mosaic in backreef lagoons on Ofu Island, American Samoa. Despite overall lack of population substructure, we identified 114 highly divergent SNPs as candidates for environmental selection, via multiple stringent outlier tests, and correlations with temperature. Corals from the warmest reef location had higher minor allele frequencies across these candidate SNPs, a pattern not seen for noncandidate loci. Furthermore, within backreef pools, colonies in the warmest microclimates had a higher number and frequency of alternative alleles at candidate loci. These data suggest mild selection for alternate alleles at many loci in these corals during high heat episodes and possible maintenance of extensive polymorphism through multilocus balancing selection in a heterogeneous environment. In this case, a natural population harbors a reservoir of alleles preadapted to high temperatures, suggesting potential for future evolutionary response to climate change. Copyright © 2014 Elsevier Ltd. All rights reserved.

Ordinary kriging vs inverse distance weighting: spatial interpolation of the sessile community of Madagascar reef, Gulf of Mexico.

PubMed

Zarco-Perello, Salvador; Simões, Nuno

2017-01-01

Information about the distribution and abundance of the habitat-forming sessile organisms in marine ecosystems is of great importance for conservation and natural resource managers. Spatial interpolation methodologies can be useful to generate this information from in situ sampling points, especially in circumstances where remote sensing methodologies cannot be applied due to small-scale spatial variability of the natural communities and low light penetration in the water column. Interpolation methods are widely used in environmental sciences; however, published studies using these methodologies in coral reef science are scarce. We compared the accuracy of the two most commonly used interpolation methods in all disciplines, inverse distance weighting (IDW) and ordinary kriging (OK), to predict the distribution and abundance of hard corals, octocorals, macroalgae, sponges and zoantharians and identify hotspots of these habitat-forming organisms using data sampled at three different spatial scales (5, 10 and 20 m) in Madagascar reef, Gulf of Mexico. The deeper sandy environments of the leeward and windward regions of Madagascar reef were dominated by macroalgae and seconded by octocorals. However, the shallow rocky environments of the reef crest had the highest richness of habitat-forming groups of organisms; here, we registered high abundances of octocorals and macroalgae, with sponges, Millepora alcicornis and zoantharians dominating in some patches, creating high levels of habitat heterogeneity. IDW and OK generated similar maps of distribution for all the taxa; however, cross-validation tests showed that IDW outperformed OK in the prediction of their abundances. When the sampling distance was at 20 m, both interpolation techniques performed poorly, but as the sampling was done at shorter distances prediction accuracies increased, especially for IDW. OK had higher mean prediction errors and failed to correctly interpolate the highest abundance values measured in situ , except for macroalgae, whereas IDW had lower mean prediction errors and high correlations between predicted and measured values in all cases when sampling was every 5 m. The accurate spatial interpolations created using IDW allowed us to see the spatial variability of each taxa at a biological and spatial resolution that remote sensing would not have been able to produce. Our study sets the basis for further research projects and conservation management in Madagascar reef and encourages similar studies in the region and other parts of the world where remote sensing technologies are not suitable for use.

Ordinary kriging vs inverse distance weighting: spatial interpolation of the sessile community of Madagascar reef, Gulf of Mexico

PubMed Central

Simões, Nuno

2017-01-01

Information about the distribution and abundance of the habitat-forming sessile organisms in marine ecosystems is of great importance for conservation and natural resource managers. Spatial interpolation methodologies can be useful to generate this information from in situ sampling points, especially in circumstances where remote sensing methodologies cannot be applied due to small-scale spatial variability of the natural communities and low light penetration in the water column. Interpolation methods are widely used in environmental sciences; however, published studies using these methodologies in coral reef science are scarce. We compared the accuracy of the two most commonly used interpolation methods in all disciplines, inverse distance weighting (IDW) and ordinary kriging (OK), to predict the distribution and abundance of hard corals, octocorals, macroalgae, sponges and zoantharians and identify hotspots of these habitat-forming organisms using data sampled at three different spatial scales (5, 10 and 20 m) in Madagascar reef, Gulf of Mexico. The deeper sandy environments of the leeward and windward regions of Madagascar reef were dominated by macroalgae and seconded by octocorals. However, the shallow rocky environments of the reef crest had the highest richness of habitat-forming groups of organisms; here, we registered high abundances of octocorals and macroalgae, with sponges, Millepora alcicornis and zoantharians dominating in some patches, creating high levels of habitat heterogeneity. IDW and OK generated similar maps of distribution for all the taxa; however, cross-validation tests showed that IDW outperformed OK in the prediction of their abundances. When the sampling distance was at 20 m, both interpolation techniques performed poorly, but as the sampling was done at shorter distances prediction accuracies increased, especially for IDW. OK had higher mean prediction errors and failed to correctly interpolate the highest abundance values measured in situ, except for macroalgae, whereas IDW had lower mean prediction errors and high correlations between predicted and measured values in all cases when sampling was every 5 m. The accurate spatial interpolations created using IDW allowed us to see the spatial variability of each taxa at a biological and spatial resolution that remote sensing would not have been able to produce. Our study sets the basis for further research projects and conservation management in Madagascar reef and encourages similar studies in the region and other parts of the world where remote sensing technologies are not suitable for use. PMID:29204321

Order of arrival affects competition in two reef fishes.

PubMed

Geange, Shane W; Stier, Adrian C

2009-10-01

Many communities experience repeated periods of colonization due to seasonally regenerating habitats or pulsed arrival of young-of-year. When an individual's persistence in a community depends upon the strength of competitive interactions, changes in the timing of arrival relative to the arrival of a competitor can modify competitive strength and, ultimately, establishment in the community. We investigated whether the strength of intracohort competitive interactions between recent settlers of the reef fishes Thalassoma hardwicke and T. quinquevittatum are dependent on the sequence and temporal separation of their arrival into communities. To achieve this, we manipulated the sequence and timing of arrival of each species onto experimental patch reefs by simulating settlement pulses and monitoring survival and aggressive interactions. Both species survived best in the absence of competitors, but when competitors were present, they did best when they arrived at the same time. Survival declined as each species entered the community progressively later than its competitor and as aggression by its competitor increased. Intraspecific effects of resident T. hardwicke were similar to interspecific effects. This study shows that the strength of competition depends not only on the identity of competitors, but also on the sequence and timing of their interactions, suggesting that when examining interaction strengths, it is important to identify temporal variability in the direction and magnitude of their effects. Furthermore, our findings provide empirical evidence for the importance of competitive lotteries in the maintenance of species diversity in demographically open marine systems.

The ploys of sex: relationships among the mode of reproduction, body size and habitats of coral-reef brittlestars

NASA Astrophysics Data System (ADS)

Hendler, Gordon; Littman, Barbara S.

1986-08-01

Observations were made of 33 species of brittlestars (3980 specimens) from specific substrata collected in four zones on the Belize Barrier Reef, Caribbean Sea. The body size of most species of brittlestars with planktonic larvae differs significantly among different substrata. Generally, individuals from the calcareous alga Halimeda opuntia are smallest, those found in corals ( Porites porites, Madracis mirabilis, and Agaricia tenuifolia) are larger, and those from coral rubble are the largest. This suggests that brittlestars with planktonic larvae move to new microhabitats as they grow. In contrast, most brooding and fissiparous species are relatively small and their size-distributions are similar among all substrata. Halimeda harbours denser concentrations of brittlestars and more small and juvenile individuals than the other substrata. Juveniles of the brooding and fissiparous species are most common in Halimeda on the Back Reef whereas juveniles developing from planktonic larvae are most common in Halimeda patches in deeper water. Fissiparity and brooding may be means for individuals (genomes) of small, apomictic species to reach large size (and correspondingly high fecundities) in patchy microhabitats that select for small body sizes. Small brittlestar species and juveniles are most numerous in the microhabitats called refuge-substrata, such as Halimeda, which may repel predators and reduce environmental stress. Whether young brittlestars are concentrated in refuge-substrata through settlement behavior, migration, or differential survival remains unknown. Experiments revealed that coral polyps kill small brittlestars, perhaps accounting for the rarity of small and juvenile brittlestars in coral substrata.

Comparative oceanography of coastal lagoons

NASA Technical Reports Server (NTRS)

Kjerfve, Bjorn

1986-01-01

The hypothesis that physical lagoon characteristics and variability depend on the channel connecting the lagoon to the adjacent coastal ocean is evaluated. The geographical, hydrological, and oceanographic characteristics of 10 lagoon systems are described and analyzed; these oceanographic features are utilized to classify the lagoon systems. Choked lagoons (Laguna Joyuda, Coorong, Lake St.Lucia, Gippsland Lakes, Lake Songkla/Thale Luang/Thale Noi, and Lagoa dos Patos) are prevalent on coasts with high wave energy and low tidal range; restricted lagoons (Lake Pontchartrain and Laguna de Terminos) are located on low/medium wave energy coasts with a low tidal range; and leaky lagoons (Mississippi Sound and Belize Lagoon/Chetumal Bay) are connected to the ocean by wide tidal passes that transmit oceanic effects into the lagoon with a minimum of resistance. The data support the hypothesis that the nature of the connecting channel controls system functions.

Diurnal carbon system variability and hydrodynamics on coral reefs of Palau and Palmyra Atoll

NASA Astrophysics Data System (ADS)

Teneva, L. T.; Dunbar, R. B.; Fleischfresser, J. D.; Koweek, D.; Koseff, J. R.; Mucciarone, D. A.

2012-12-01

The rates of coral reef response to ocean pH changes and the implications for ecosystem resilience remain largely unknown. Our ability to predict the impacts of ocean acidification hinges on an improved understanding of temporal and spatial measurements of coral reef carbon budgets. Here we report on the first 5-minute resolution multi-day carbon system measurements from Palau and Palmyra Atoll collected in April 2011 and September 2011, respectively. Our experimental approach uses a custom-made automated continuous flow system capable of resolving pH, temperature, and salinity on a 10-second timescale, and Dissolved Inorganic Carbon (DIC) on a 5-minute timescale. At Palmyra Atoll, a lagoonal site of North Barren Island (NBI) was characterized by high amplitude in diel biogeochemical variability: pH 7.93-8.2 (mean: 8.06± 0.06), pCO2 211.4-535.2 (μatm) (mean: 364.8 ± 72.2) nTA 2141.5-2297.5 (μmol/kg) (mean: 2216.7 ± 35.2), nDIC 1626.5 - 2069.9(μmol/kg) (mean: 1908.4 ± 86.3), ΩARAG 3.04-5 (mean: 3.91 ± 0.43), and dissolved oxygen 100.6-285.0 (mL/L) (mean: 178.4 ± 47.3). Variability observed at well-mixed back reef site at Palmyra Atoll, named Penguin Spit, was smaller compared with NBI: pH 8.06-8.18 (mean: 8.12 ± 0.03), pCO2 263.6-380.4 (μatm) (mean: 319.9 ± 29.0), nTA 2232.0-2307.8 (μmol/kg) (mean: 2278.9 ± 15.2), nDIC 1848.2-2052.0 (μmol/kg) (mean: 1972.8 ± 35.4), and ΩARAG 4.03-4.99 (mean: 4.5 ± 0.24), and dissolved oxygen 155.4-214.2 (mL/L) (mean: 181.4 ± 15.5). At Palau we observe the following ranges in a backreef environment: pH 8.07-8.24 (mean: 8.15 ± 0.03), pCO2 330.6-519.9 (μatm) (mean: 420.9 ± 35.2), nTA 2171.1-2357.8 (μmol/kg) (mean: 2234.1 ± 25.2), nDIC 1834.4-2120.6 μmol/kg (mean: 1954.3±35.8), ΩARAG 2.84-3.98 (mean: 3.36 ±0.2). Local hydrodynamics can attenuate or enhance coral reef metabolism signals within the water column to different extent at different reef sites. Such field studies contribute to a broader database of reefal carbon budgets and highlight the need for future ocean acidification impact projections to account for inter- and intra-island spatial heterogeneity in pH conditions and commensurate net community calcification and net community production rates.

Regional stratigraphy and subsurface geology of Cenozoic deposits, Gulf Coastal Plain, south-central United States

USGS Publications Warehouse

Hosman, R.L.

1991-01-01

Although Cenozoic deposits are not uniformly differentiated, interstate correlations of major Paleocene and Eocene units are generally established throughout the area. Younger deposits are not as well differentiated. Some stratigraphic designations made at surface exposures cannot be extended into the sub-surface, and the scarcity of distinct geologic horizons has hampered differentiation on a regional scale. The complexities of facies development in Oligocene and younger coastal deposits preclude the development of extensive recognizable horizons needed for stratigraphic applications. Coastal deposits are a heterogeneous assemblage of deltaic, lagoonal, lacustrine, palustrine, eolian, and fluvial clastic facies and local calcareous reef facies. Even major time boundaries, as between geologic series, are not fully resolved. Surficial Quaternary deposits overlie the truncated subcrops of Tertiary strata and generally are distinguishable, although some contacts between Pleistocene and underlying Pliocene deposits have been a ?lstoncal source of controversy. Glacially related terraces are characteristic of the Pleistocene Epoch, and alluvium of aggrading streams typifies the Holocene. 

Mercury Concentrations in Coastal Sediment from Younger Lagoon, Central California

NASA Astrophysics Data System (ADS)

Hohn, R. A.; Ganguli, P. M.; Swarzenski, P. W.; Richardson, C. M.; Merckling, J.; Johnson, C.; Flegal, A. R.

2013-12-01

Younger Lagoon Reserve, located in northern Monterey Bay, is one of the few relatively undisturbed wetlands that remain along the Central Coast of California. This lagoon system provides protected habitat for more than 100 bird species and for populations of fish, mammals, and invertebrates. Total mercury (HgT) concentrations in water within Younger Lagoon appear to vary with rainfall conditions and range from about 5-15 pM. These concentrations are similar to HgT in water from six nearby lagoon systems. However, Younger Lagoon contains elevated concentrations of dissolved organic carbon (~1 mM) and monomethylmercury (MMHg, ~1 pM) relative to our comparison lagoon sites (DOC < 0.5 mM and MMHg < 0.5 pM). We attribute Younger Lagoon's high DOC and MMHg to its restricted connection to the ocean and minor riverine contribution. Coastal lagoons in this region typically form at the mouth of streams. They behave as small estuaries during the wet season when surface water discharge keeps the mouth of the stream open to the ocean, and then transition into lagoons in the dry season when a sand berm develops and effectively cuts off surface water exchange. At Younger Lagoon, the sand berm remains intact throughout the year, breaching only during particularly high tides or intense rain events. Therefore, the lagoon's connection to nearshore seawater is primarily via surface water - groundwater interaction through the sand berm. Because Younger Lagoon is largely isolated from a surface water connection with the ocean, runoff from upgradient urban and agricultural land has an enhanced impact on water (and presumably sediment) quality. As a result, the lagoon is eutrophic and experiences annual algal blooms. Groundwater surveys suggest surface water, groundwater, and coastal seawater are hydraulically connected at Younger Lagoon, and mixing among these water masses appears to influence water geochemistry. To date, no chemical analyses have been conducted on sediment from Younger Lagoon. To address this data gap we collected sediment samples during a February 2013 field campaign. One set of sediment samples is from the bottom of the lagoon along a transect perpendicular to the shoreline and another set is from an approximately 1 m depth profile on the lagoon side of the sand berm (depth of the groundwater table at the time of collection). These samples are being analyzed for HgT, MMHg, and total organic carbon (TOC) and will provide a first glimpse into the distribution of mercury species and organic carbon in sediments from the Younger Lagoon Reserve. We will also collect and analyze sediment samples from another lagoon site with comparable watershed characteristics.

Cryptic effects of habitat declines: coral-associated fishes avoid coral-seaweed interactions due to visual and chemical cues.

PubMed

Brooker, Rohan M; Brandl, Simon J; Dixson, Danielle L

2016-01-04

Seaweed-dominated coral reefs are becoming increasingly common as environmental conditions shift away from those required by corals and toward those ideal for rampant seaweed growth. How coral-associated organisms respond to seaweed will not only impact their fate following environmental change but potentially also the trajectories of the coral communities on which they rely. However, behavioral responses by coral-associated organisms to seaweeds are poorly understood. This study examined interactions between a guild of obligate and opportunistic coral-feeding butterflyfishes (Chaetodontidae) and scleractinian corals to determine whether fishes continue to interact with corals in contact with seaweed or if they are avoided. Under natural conditions, all species interacted almost exclusively with seaweed-free corals. In a controlled patch reef experiment, fishes avoided corals in physical contact with seaweed, irrespective of dietary preferences. When visual seaweed cues were removed, butterflyfish continued to avoid corals that had been in contact with the allelopathic Galaxaura filamentosa, suggesting that chemical cues produced by coral-seaweed interactions are repellent. These findings suggest that, due to deleterious visual and chemical cues produced by coral-seaweed interactions, coral-associated organisms may struggle to locate resources as seaweed-free corals decline in abundance.

Revised Stratigraphy of The Nallıhan-Dudaş (Beypazarı) Area and Significance of the Campanian-Maastrichtian Reef Occurrences Based on the Foraminiferal and Rudist Data

NASA Astrophysics Data System (ADS)

Görmüş, Muhittin; Sami Us, Muhammed; Özer, Sacit; Tekin, Erdoǧan; Akpınar, Serap; Kabakcı, Büşra

2016-04-01

Transgressive to regressive succession of the Cretaceous Period and Cretaceous Paleogene boundary from the Nallıhan-Beypazarı area have significant data to interpret the past geological history of northwestern Turkey. In the literature, main scientific differences are seen on the formation/lithodem names, their ages, contact relations and environmental interpretations. In the study, a revision has been made for a proper stratigraphy of the area. For the revised stratigraphy, the obtained results from our field and laboratory works and the literature information were used. The following stratigraphy were established from basement to top: the Permo-Triassic aged Sekli metamorphics, Jurassic to lower Cretaceous Soǧukçam formation, Campanian to Maastrichtian aged Dereköy Group-Haremiköy conglomerates, Çeǧiköy reefs, Nardin formation (Seben formation), Taraklı formation; the Paleogene aged Kızılçay group including Kızılbayır formation, Karaköy volcanoclastics, Selvipınar limestone, the Miocene-Pliocene terrestrial sediments, Çoraklar formation, Hırka formation, Akpınar formation, Çayırhan formation, Teke volkanics, Bozbelen formation, Kirmir formation. The main unconformities are between Jura and Campanian, Maastrichtian and Paleogene, Eocene and Miocene times. Among the geological units, the Çeǧiköy reefs having rich rudist fauna overlie the Haremiköy conglomerates in both sides at the north-Yeşilyurt village and at the south-Gökçeöz village. Another outcrop, Emincik is between two mentioned villages. Biohermal reefs mainly includes very rich rudists up to 40 centimetres in size around the Yeşilköy such as: Pironaea polystyla, Vaccinites loftusi, Hippurites sublaevis. Larger foraminifera Orbitoides medius, O. apiculatus, Siderolites calcitrapoides, Pseodosiderolites vidali are also common in the fore reef areas. Around the Gökçeöz at the south part, the identified rudists are as follows: Vaccinites sp., Hippurites aff. sublaevis, Pironaea polystyla Joufia cf. reticulata, Hippuritella variabilis. In this location, smaller rudists are at the bottom, larger ones are at the top of the biostromal limestones. The first reefal occurrences are interpreted as local fringing type reefs. The reefs around the Emincik are the second occurrences of reefs. This was interpreted as patch reefs. Rudist fauna are less than the other locations and it occurs above the orbitoid rich siliciclastics. Extinction of rudists is at the end of middle Maastrichtian due to paleoenvironmental changes and open marine conditions. Transgressive succession continuous with regressive succession. The Taraklı Formation siliciclastics including rich Orbitoides apiculatus and O. gruenbachensis. The location is also important for the mass larger foraminifera-Orbitoides extinction on the Cretaceous/Paleogene boundary. Terrestrial siliciclastics overlies the very shallow marine Maastrichtian siliciclastics. ACKNOWLADGEMENT: The authors thanks to Ankara University Scientific Research Projects Coordination Unit (BAP) for the financial support on the project 13B4343014.

Aerated Lagoons. Student Manual. Biological Treatment Process Control.

ERIC Educational Resources Information Center

Andersen, Lorri

This student manual contains the textual material for a unit which focuses on the structural and operationally unique features of aerated lagoons. Topic areas discussed include: (1) characteristics of completely mixed aerated lagoons; (2) facultative aerated lagoons; (3) aerated oxidation ponds; (4) effects of temperature on aerated lagoons; (5)…

Flushing of a coastal lagoon in the Red Sea

NASA Astrophysics Data System (ADS)

Sultan, S. A. R.; Ahmad, F.

1990-09-01

Shu'aiba Lagoon (Lat. 20°45'N; Long. 39°28'E) is located on the eastern coast of the Red Sea. It is relatively shallow with an area of approximately 11·7 km 2. The inlet to the lagoon is narrow with a cross-sectional area of about 245 m 2. This lagoon is a future site to develop mariculture. With this objective in view the flushing time scale of the lagoon was calculated, as flushing is an important abiotic factor in lagoon ecology. The average flushing time for the months February to June and September to November is about 20 days. Oceanic inputs play an important part in the process of fertilization of the lagoons. The marine environment in arid zone lagoons is under natural stress due to high temperatures and salinities. However, the flushing time scale of 20 days may not exert intolerable stress on the ecology of the Shu'aiba Lagoon.

Monitoring Corals and Submerged Aquatic Vegetation in Western Pacific Using Satellite Remote Sensing Integrated with Field Data

NASA Astrophysics Data System (ADS)

Roelfsema, C. M.; Phinn, S. R.; Lyons, M. B.; Kovacs, E.; Saunders, M. I.; Leon, J. X.

2013-12-01

Corals and Submerged Aquatic Vegetation (SAV) are typically found in highly dynamic environments where the magnitude and types of physical and biological processes controlling their distribution, diversity and function changes dramatically. Recent advances in the types of satellite image data and the length of their archives that are available globally, coupled with new techniques for extracting environmental information from these data sets has enabled significant advances to be made in our ability to map and monitor coral and SAV environments. Object Based Image Analysis techniques are one of the most significant advances in information extraction techniques for processing images to deliver environmental information at multiple spatial scales. This poster demonstrates OBIA applied to high spatial resolution satellite image data to map and monitor coral and SAV communities across a variety of environments in the Western Pacific that vary in their extent, biological composition, forcing physical factors and location. High spatial resolution satellite imagery (Quickbird, Ikonos and Worldview2) were acquired coincident with field surveys on each reef to collect georeferenced benthic photo transects, over various areas in the Western Pacific. Base line maps were created, from Roviana Lagoon Solomon island (600 km2), Bikini Atoll Marshall Island (800 Km2), Lizard Island, Australia (30 km2) and time series maps for geomorphic and benthic communities were collected for Heron Reef, Australia (24 km2) and Eastern Banks area of Moreton Bay, Australia (200 km2). The satellite image data were corrected for radiometric and atmospheric distortions to at-surface reflectance. Georeferenced benthic photos were acquired by divers or Autonomous Underwater Vehicles, analysed for benthic cover composition, and used for calibration and validation purposes. Hierarchical mapping from: reef/non-reef (1000's - 10000's m); reef type (100's - 1000's m); 'geomorphic zone' (10's - 100's m); to dominant components of benthic cover compositions (1 - 10's m); and individual benthic cover type scale (0.5-5.0's m), was completed using object based segmentation and semi-automated labelling through membership rules. Accuracy assessment of the satellite image based maps and field data sets scales maps produced with 90% maximum accuracy larger scales and less complex maps, versus 40 % at smaller scale and complex maps. The study showed that current data sets and object based analysis are able to reliable map at various scales and level of complexity covering a variety of extent and environments at various times; as a result science and management can use these tools to assess and understand the ecological processes taking place in coral and SAV environments.

Mapping Submarine Groundwater Discharge - how to investigate spatial discharge variability on coastal and beach scales

NASA Astrophysics Data System (ADS)

Stieglitz, T. C.; Burnett, W. C.; Rapaglia, J.

2008-12-01

Submarine groundwater discharge (SGD) is now increasingly recognized as an important component in the water balance, water quality and ecology of the coastal zone. A multitude of methods are currently employed to study SGD, ranging from point flux measurements with seepage meters to methods integrating over various spatial and temporal scales such as hydrological models, geophysical techniques or surface water tracer approaches. From studies in a large variety of hydrogeological settings, researchers in this field have come to expect that SGD is rarely uniformly distributed. Here we discuss the application of: (a) the mapping of subsurface electrical conductivity in a discharge zone on a beach; and (b) the large-scale mapping of radon in coastal surface water to improving our understanding of SGD and its spatial variability. On a beach scale, as part of intercomparison studies of a UNESCO/IAEA working group, mapping of subsurface electrical conductivity in a beach face have elucidated the non-uniform distribution of SGD associated with rock fractures, volcanic settings and man-made structures (e.g., piers, jetties). Variations in direct point measurements of SGD flux with seepage meters were linked to the subsurface conductivity distribution. We demonstrate how the combination of these two techniques may complement one another to better constrain SGD measurements. On kilometer to hundred kilometer scales, the spatial distribution and regional importance of SGD can be investigated by mapping relevant tracers in the coastal ocean. The radon isotope Rn-222 is a commonly used tracer for SGD investigations due to its significant enrichment in groundwater, and continuous mapping of this tracer, in combination with ocean water salinity, can be used to efficiently infer locations of SGD along a coastline on large scales. We use a surface-towed, continuously recording multi-detector setup installed on a moving vessel. This tool was used in various coastal environments, e.g. in Florida, Brazil, Mauritius and Australia's Great Barrier Reef lagoon. From shore-parallel transects along the Central Great Barrier Reef coastline, numerous processes and locations of SGD were identified, including terrestrially-derived fresh SGD and the recirculation of seawater in mangrove forests, as well as riverine sources. From variations in the inverse relationship of the two tracers radon and salinity, some aspects of regional freshwater input into the lagoon during the tropical wet season could be assessed. Such surveys on coastal scales can be a useful tool to obtain an overview of locations and processes of SGD on an unknown coastline.

Groundwater-driven nutrient inputs to coastal lagoons: The relevance of lagoon water recirculation as a conveyor of dissolved nutrients.

PubMed

Rodellas, Valentí; Stieglitz, Thomas C; Andrisoa, Aladin; Cook, Peter G; Raimbault, Patrick; Tamborski, Joseph J; van Beek, Pieter; Radakovitch, Olivier

2018-06-16

Evaluating the sources of nutrient inputs to coastal lagoons is required to understand the functioning of these ecosystems and their vulnerability to eutrophication. Whereas terrestrial groundwater processes are increasingly recognized as relevant sources of nutrients to coastal lagoons, there are still limited studies evaluating separately nutrient fluxes driven by terrestrial groundwater discharge and lagoon water recirculation through sediments. In this study, we assess the relative significance of these sources in conveying dissolved inorganic nutrients (NO 3 - , NH 4 + and PO 4 3- ) to a coastal lagoon (La Palme lagoon; France, Mediterranean Sea) using concurrent water and radon mass balances. The recirculation of lagoon water through sediments represents a source of NH 4 + (1900-5500 mol d -1 ) and PO 4 3- (22-71 mol d -1 ), but acts as a sink of NO 3 - . Estimated karstic groundwater-driven inputs of NO 3 - , NH 4 + and PO 4 3- to the lagoon are on the order of 200-1200, 1-12 and 1.5-8.7 mol d -1 , respectively. A comparison between the main nutrient sources to the lagoon (karstic groundwater, recirculation, diffusion from sediments, inputs from a sewage treatment plant and atmospheric deposition) reveals that the recirculation of lagoon water through sediments is the main source of both dissolved inorganic nitrogen (DIN) and phosphorous (DIP) to La Palme lagoon. These results are in contrast with several studies conducted in systems influenced by terrestrial groundwater inputs, where groundwater is often assumed to be the main pathway for dissolved inorganic nutrient loads. This work highlights the important role of lagoon water recirculation through permeable sediments as a major conveyor of dissolved nutrients to coastal lagoons and, thus, the need for a sound understanding of the recirculation-driven nutrient fluxes and their ecological implications to sustainably manage lagoonal ecosystems. Copyright © 2018. Published by Elsevier B.V.

Lagoon Seepage Testing Report for Central Facilities Area (CFA) Sewage Lagoons at Idaho National Laboratory, Butte County, Idaho

DOE Office of Scientific and Technical Information (OSTI.GOV)

Morrison, Bridger

J-U-B ENGINEERS, Inc. (J-U-B) performed seepage tests on the CFA Wastewater Lagoons 1, 2, and 3 between August 26th and September 22nd, 2014. The lagoons were tested to satisfy the Idaho Department of Environmental Quality (DEQ) Rules (IDAPA 58.01.16) that require all lagoons be tested at a frequency of every 10 years and the Compliance Activity CA-141-03 in the DEQ Wastewater Reuse Permit for the CFA Sewage Treatment Plant (LA-000141-03). The lagoons were tested to determine if the average seepage rates are less than 0.25 in/day, the maximum seepage rate allowed for lagoons built prior to April 15, 2007. Themore » average seepage rates were estimated for each lagoon and are given in Table-ES1. The average seepage rates for Lagoons 1 and 2 are less than the allowable seepage rate of 0.25 in/day. Lagoon 1 and 2 passed the seepage test and will not have to be tested again until the year 20241. However, the average seepage rate for Lagoon 3 appears to exceed the allowable seepage rate of 0.25 in/day which means the potential source for the excessive leakage should be investigated further.« less

Fish fauna recovery in a newly re-flooded Mediterranean coastal lagoon

NASA Astrophysics Data System (ADS)

Koutrakis, Emmanuil; Sylaios, Georgios; Kamidis, Nikolaos; Markou, Dimitrios; Sapounidis, Argyris

2009-08-01

Drana Lagoon, located at the NW site of Evros River Delta, was drained in 1987 and re-flooded in 2004 within the framework of an integrated wetland restoration project. This study presents the results of a monitoring program of the lagoon's oceanographic, water quality and fish fauna characteristics, during the pre- and post-restoration period. Results depict the presence of high salinity water (up to 41) due to seawater intrusion, strong evaporation in its interior and inadequate freshwater inflows. Overall, nutrient levels were low depicting local changes. Tidal variability at the mouth was approximately 0.2 m, producing high velocity tidal currents (up to 0.75 m/s). Eleven fish fauna species were collected; seven species were caught in both the inlet channel and the lagoon during the pre-restoration period and nine species in the post-restoration period. Atherina boyeri (37.6%) and Pomatoschistus marmoratus (31.7%) dominated the lagoon during the post-restoration period. Most of the A. boyeri specimens (88.5%) were caught inside the lagoon, while P. marmoratus had an almost equal distribution in the inlet channel and the lagoon (56.3% and 43.7% respectively). The presence of species of the Mugilidae family (5.2% total average catches after lagoon re-flooding) was mainly in the inlet channel (12.6% of the average catches) and not inside the lagoon (only 1.3% of the average catches). The small number of fish species inhabiting the lagoon might be the result of the recent restoration or it could be related with the increased water flow observed at the lagoon mouth during the flood and ebb tidal phases, and also in the presence of a smooth bank in the concrete waterspout that connects the entrance channel with the lagoon. The limited presence of the Mugilidae juveniles inside the lagoon could be related to the prevailing tidal inlet dynamics (i.e. strong ebb flow at lagoon inlet), thus preventing the species to enter the lagoon. In order to restore the lagoon environment, careful and gradual steps should be undertaken under the basis of continuous monitoring of hydrologic, environmental and fisheries system's status.

Sludge Lagoons. Sludge Treatment and Disposal Course #166. Instructor's Guide [and] Student Workbook.

ERIC Educational Resources Information Center

Sharman, Ronald M.

This lesson describes three different types of sludge lagoons: (1) drying lagoons; (2) facultative lagoons; and (3) anaerobic lagoons. Normal operating sequence and equipment are also described. The lesson is designed to be used in sequence with the complete Sludge Treatment and Disposal Course #166 or as an independent lesson. The instructor's…

Phytotoxicity of Four Photosystem II Herbicides to Tropical Seagrasses

PubMed Central

Flores, Florita; Collier, Catherine J.; Mercurio, Philip; Negri, Andrew P.

2013-01-01

Coastal waters of the Great Barrier Reef (GBR) are contaminated with agricultural pesticides, including the photosystem II (PSII) herbicides which are the most frequently detected at the highest concentrations. Designed to control weeds, these herbicides are equally potent towards non-target marine species, and the close proximity of seagrass meadows to flood plumes has raised concerns that seagrasses may be the species most threatened by herbicides from runoff. While previous work has identified effects of PSII herbicides on the photophysiology, growth and mortality in seagrass, there is little comparative quantitative toxicity data for seagrass. Here we applied standard ecotoxicology protocols to quantify the concentrations of four priority PSII herbicides that inhibit photochemistry by 10, 20 and 50% (IC10, IC20 and IC50) over 72 h in two common seagrass species from the GBR lagoon. The photosystems of seagrasses Zostera muelleri and Halodule uninervis were shown to be generally more sensitive to the PSII herbicides Diuron, Atrazine, Hexazinone and Tebuthiuron than corals and tropical microalgae. The herbicides caused rapid inhibition of effective quantum yield (∆F/F m ′), indicating reduced photosynthesis and maximum effective yields (Fv/Fm) corresponding to chronic damage to PSII. The PSII herbicide concentrations which affected photosynthesis have been exceeded in the GBR lagoon and all of the herbicides inhibited photosynthesis at concentrations lower than current marine park guidelines. There is a strong likelihood that the impacts of light limitation from flood plumes and reduced photosynthesis from PSII herbicides exported in the same waters would combine to affect seagrass productivity. Given that PSII herbicides have been demonstrated to affect seagrass at environmental concentrations, we suggest that revision of environmental guidelines and further efforts to reduce PSII herbicide concentrations in floodwaters may both help protect seagrass meadows of the GBR from further decline. PMID:24098726

Phytotoxicity of four photosystem II herbicides to tropical seagrasses.

PubMed

Flores, Florita; Collier, Catherine J; Mercurio, Philip; Negri, Andrew P

2013-01-01

Coastal waters of the Great Barrier Reef (GBR) are contaminated with agricultural pesticides, including the photosystem II (PSII) herbicides which are the most frequently detected at the highest concentrations. Designed to control weeds, these herbicides are equally potent towards non-target marine species, and the close proximity of seagrass meadows to flood plumes has raised concerns that seagrasses may be the species most threatened by herbicides from runoff. While previous work has identified effects of PSII herbicides on the photophysiology, growth and mortality in seagrass, there is little comparative quantitative toxicity data for seagrass. Here we applied standard ecotoxicology protocols to quantify the concentrations of four priority PSII herbicides that inhibit photochemistry by 10, 20 and 50% (IC10, IC20 and IC50) over 72 h in two common seagrass species from the GBR lagoon. The photosystems of seagrasses Zosteramuelleri and Haloduleuninervis were shown to be generally more sensitive to the PSII herbicides Diuron, Atrazine, Hexazinone and Tebuthiuron than corals and tropical microalgae. The herbicides caused rapid inhibition of effective quantum yield (∆F/F m '), indicating reduced photosynthesis and maximum effective yields (Fv/Fm ) corresponding to chronic damage to PSII. The PSII herbicide concentrations which affected photosynthesis have been exceeded in the GBR lagoon and all of the herbicides inhibited photosynthesis at concentrations lower than current marine park guidelines. There is a strong likelihood that the impacts of light limitation from flood plumes and reduced photosynthesis from PSII herbicides exported in the same waters would combine to affect seagrass productivity. Given that PSII herbicides have been demonstrated to affect seagrass at environmental concentrations, we suggest that revision of environmental guidelines and further efforts to reduce PSII herbicide concentrations in floodwaters may both help protect seagrass meadows of the GBR from further decline.

Remote high-definition rotating video enables fast spatial survey of marine underwater macrofauna and habitats.

PubMed

Pelletier, Dominique; Leleu, Kévin; Mallet, Delphine; Mou-Tham, Gérard; Hervé, Gilles; Boureau, Matthieu; Guilpart, Nicolas

2012-01-01

Observing spatial and temporal variations of marine biodiversity from non-destructive techniques is central for understanding ecosystem resilience, and for monitoring and assessing conservation strategies, e.g. Marine Protected Areas. Observations are generally obtained through Underwater Visual Censuses (UVC) conducted by divers. The problems inherent to the presence of divers have been discussed in several papers. Video techniques are increasingly used for observing underwater macrofauna and habitat. Most video techniques that do not need the presence of a diver use baited remote systems. In this paper, we present an original video technique which relies on a remote unbaited rotating remote system including a high definition camera. The system is set on the sea floor to record images. These are then analysed at the office to quantify biotic and abiotic sea bottom cover, and to identify and count fish species and other species like marine turtles. The technique was extensively tested in a highly diversified coral reef ecosystem in the South Lagoon of New Caledonia, based on a protocol covering both protected and unprotected areas in major lagoon habitats. The technique enabled to detect and identify a large number of species, and in particular fished species, which were not disturbed by the system. Habitat could easily be investigated through the images. A large number of observations could be carried out per day at sea. This study showed the strong potential of this non obtrusive technique for observing both macrofauna and habitat. It offers a unique spatial coverage and can be implemented at sea at a reasonable cost by non-expert staff. As such, this technique is particularly interesting for investigating and monitoring coastal biodiversity in the light of current conservation challenges and increasing monitoring needs.

Spatial variability in fish species assemblage and community structure in four subtropical lagoons of the Okavango Delta, Botswana

NASA Astrophysics Data System (ADS)

Mosepele, K.; Mosepele, B.; Bokhutlo, T.; Amutenya, K.

The species assemblage and community structure of four lagoons was assessed through time series data collected between 2001 and 2005 in the Okavango Delta. The main aim of this study was to evaluate the importance of lagoons as fish habitats in the Delta. Therefore, this study assessed the importance of these habitats through determining fish species diversity, composition, relative abundance, and community structure between the lagoons. Forty six species belonging to 11 families and five orders were collected over the study period. Main results showed that Cichlidae was the most important family and had the highest species richness in the lagoons. Significant differences ( p < 0.05) were observed in species richness, faunal composition, and diversity among some of the lagoons. Moreover, there were also variations in species composition, and also significant differences in mean length and weight of some selected fish species in the four lagoons. This study showed that lagoons are important repositories of food fish to local communities. Moreover, a management of the fish stocks based on restricting fishing in some lagoons as protected areas is not feasible because of these significant differences in species assemblages between lagoons. Furthermore, lagoons are subject to multiple where most of the lodges are constructed, which makes subsequently makes them vulnerable to pollution. Therefore, the integrity of lagoon habitats needs to be maintained so that their ecosystem functioning (i.e. fish repositories) is maintained.

Are coastal lagoons physically or biologically controlled ecosystems? Revisiting r vs. K strategies in coastal lagoons and estuaries

NASA Astrophysics Data System (ADS)

Pérez-Ruzafa, Angel; Marcos, Concepción; Pérez-Ruzafa, Isabel María; Pérez-Marcos, María

2013-11-01

Environmental stress influences biological assemblages, with species responding to stress by adopting particular life-history strategies (e.g., r vs. K). Coastal lagoons and estuaries are considered naturally stressed and physically controlled systems with frequent environmental disturbances and fluctuations. At the same time, their transitional nature (between terrestrial, freshwater and marine) makes them especially vulnerable to human impacts and land and freshwater inputs. As a result, it is hypothesised that residents of coastal lagoons would display characteristics of r-selected species. The r-strategy involves increased reproductive effort through early reproduction, small and numerous offspring with a large dispersive capability, short lifespan and small adult body size. Together, these traits provide a selective advantage in such unpredictable or short-lived environments. Alternatively, immigrants to coastal lagoons should mostly be K-strategists, with a competitive advantage over the r-strategists, at least on a temporary time scale. These hypotheses were explored using a dataset from 73 Atlanto-Mediterranean sites: 27 estuaries, 42 coastal lagoons and 4 from the sea, obtained from published sources. A detailed analysis of the distributions of the different resident fish species according to lagoon characteristics indicated that in lagoons with a higher marine influence the families Gobiidae, Blenniidae and Syngnathidae were common, while lagoons with freshwater influence are characterized by Cyprinidae and other freshwater species. In analyzing the biological strategies of lagoon species we found that fish assemblages inhabiting marine influenced lagoons were characterized by solitary, necto-benthonic sedentary species. These species are often hermaphroditic, with benthic broods and many exhibit brooding behaviour. This suggests that marine influenced lagoons are dominated by K-strategist species, while r-strategy species will be more common in freshwater lagoons and among marine migrant species.

Assessing hog lagoon waste contamination in the Cape Fear Watershed using Bacteroidetes 16S rRNA gene pyrosequencing.

PubMed

Arfken, Ann M; Song, Bongkeun; Mallin, Michael A

2015-09-01

Hog lagoons can be major sources of waste and nutrient contamination to watersheds adjacent to pig farms. Fecal source tracking methods targeting Bacteroidetes 16S rRNA genes in pig fecal matter may underestimate or fail to detect hog lagoon contamination in riverine environments. In order to detect hog lagoon wastewater contamination in the Cape Fear Watershed, where a large number of hog farms are present, we conducted pyrosequencing analyses of Bacteroidetes 16S rRNA genes in hog lagoon waste and identified new hog lagoon-specific marker sequences. Additional pyrosequencing analyses of Bacteroidetes 16S rRNA genes were conducted with surface water samples collected at 4 sites during 5 months in the Cape Fear Watershed. Using an operational taxonomic unit (OTU) identity cutoff value of 97 %, these newly identified hog lagoon markers were found in 3 of the river samples, while only 1 sample contained the pig fecal marker. In the sample containing the pig fecal marker, there was a relatively high percentage (14.1 %) of the hog lagoon markers and a low pig fecal marker relative abundance of 0.4 % in the Bacteroidetes 16S rRNA gene sequences. This suggests that hog lagoon contamination must be somewhat significant in order for pig fecal markers to be detected, and low levels of hog lagoon contamination cannot be detected targeting only pig-specific fecal markers. Thus, new hog lagoon markers have a better detection capacity for lagoon waste contamination, and in conjunction with a pig fecal marker, provide a more comprehensive and accurate detection of hog lagoon waste contamination in susceptible watersheds.

Metals in some lagoons of Mexico.

PubMed

Vazquez, F G; Sharma, V K; Alexander, V H; Frausto, C A

1995-02-01

The concentrations of metals, Cd, Cu, Fe, Mn, Ni, Pb, and Zn were determined in some lagoons to establish the level of metal pollution. The lagoons studied were Alvarado lagoon, Veracruz; San Andres lagoon, Tamaulipas; and Terminos lagoon, Campeche. The concentrations were determined in water, oyster (Crassostrea virginica), and sediments. Metals were accumulated in either oysters or sediments. Cu and Zn were higher in oysters and Fe and Mn were higher in sediments. The results in water samples were compared with the limit established by the Secretaria de Ecologia and Desarrollo Urbano Report and briefly discussed.

Lagoon Restoration Project: Final report

DOE Office of Scientific and Technical Information (OSTI.GOV)

NONE

This project is a multiyear effort focusing on energy flow in the Palace of Fine Arts lagoon just outside the Exploratorium in San Francisco. Phase 1 was a pilot study to determine the feasibility of improving biological energy flow through the small freshwater lagoon, using the expertise and resources of an environmental artist in collaboration with museum biologists and arts department staff. The primary outcome of Phase 1 is an experimental fountain exhibit inside the museum designed by public artist Laurie Lundquist with Exploratorium staff. This fountain, with signage, functions both as a model for natural aeration and filtration systemsmore » and as a focal point for museum visitors to learn about how biological processes cycle energy through aquatic systems. As part of the study of the lagoon`s health, volunteers continued biweekly bird consus from March through September, 1994. The goal was to find out whether the poor water quality of the lagoon is affecting the birds. Limited dredging was undertaken by the city Parks and Recreation Department. However, a more peermanent solution to the lagoon`s ecological problems would require an ambitious redesign of the lagoon.« less

Spatial and temporal controls of atoll island inundation: implications for urbanized atolls in the Marshall Islands.

NASA Astrophysics Data System (ADS)

Ford, M.; Becker, J. M.; Merrifield, M. A.

2012-12-01

Atoll islands are highly vulnerable to a range of inundation hazards. The impacts of such hazards are expected to be magnified as a result of continued sea-level rise. Both recent and historic inundation events provide unique insights into the requisite conditions necessary to initiate island inundation. A number of recent and historic inundation events are presented in order to examine the oceanographic and meteorological conditions driving inundation of a densely populated, urbanized atoll in the central Pacific. Analysis of inundation events suggests that a number of key drivers contribute to the spatial and temporal extent of island inundation, with unique degrees of predictability and resultant impact signatures apparent on island geomorphology and local anthropogenic activities. Results indicate three distinct drivers of inundation hazards exist. Firstly, tropical storms and typhoons elevate sea level through inverse barometric setup, wind setup and a range of wave driven processes and have caused considerable impact on atolls within the Marshall Islands. Secondly, super-elevated sea level conditions resulting from the combination of seasonal high tides and quasi-cyclical La Nina conditions drive inundation of low-lying lagoon facing coastal areas. Thirdly, long period swell conditions, typically generated by distant storms, can elevate reef-flat water levels through wave setup and infragravity wave oscillations. Such wave conditions can over wash the ocean-facing island ridge, often inundating large sections of the island. Reef-flat wave conditions are tidally modulated, with inundation events typically occurring around high tide. However, the two most recent destructive swell-driven inundation events have occurred while tide levels were significantly lower than spring tide levels, suggesting high water levels are not a necessary prerequisite for wave-driven inundation. The different modes of inundation are discussed and grounded within recent and historic inundation events, as well as results of a lengthy reef flat wave observation dataset from Kwajalein and Majuro Atolls in the Republic of the Marshall Islands. Future impacts of continued sea-level rise are considered on each mode of island inundation and the implications for local response discussed within the context of urbanised atoll islands.

Response to short term ultraviolet stress in the reef-building coral Pocillopora capitata (Anthozoa: Scleractinia).

PubMed

Liñán-Cabello, Marco A; Flores-Ramírez, Laura A; Cobo-Díaz, José Francisco; Zenteno-Savin, Tania; Olguín-Monroy, Norma O; Olivos-Ortiz, Aramís; Tintos-Gómez, Adrián

2010-03-01

Coral reefs are impacted by a range of environmental variables that affect their growth and survival, the main factors being the high irradiance and temperature fluctuations. Specimens of Pocillopora capitata Verrill 1864 were exposed to photosynthetically active radiation (PAR) and ultraviolet radiation (UVR) for 32 h under laboratory conditions. We examined lipid peroxidation (MDA), antioxidant enzyme activities (SOD, CAT, GPx and GST), chlorophyll a (Chl a), carotenoid pigments (CPs), mycosporine-like amino acids (MAAs), and expulsion of zooxanthellae. Our results revealed that corals exposed to UVR had relatively low levels of carotenoids and antioxidant enzyme activities compared to those exposed to PAR, as well as lower CPs/Chl a ratios. Although MAAs and CPs are rapidly produced as non-enzymatic antioxidants in response to UVR in corals, these were not sufficient, even in the dark phase of the experiment, to mitigate the damage caused by formation of reactive oxygen species (ROS), which caused breakdown of the symbiotic relationship between the zooxanthellae and the host animal to an extent 33 times greater than in the PAR treatment. In this study, it could be possible to distinguish that, parallel to the short-term adjustments, such as the amount of pigment in the algae or the sensitivity of the photosynthetic response reported in other species of coral, P. capitata exhibits at the enzymatic level a series of responses oriented to resist the effects derived from the propagation of ROS and, thus, to adapt to and maintain its reproductive capacity in shallow oceanic environments that commonly exhibit high UVR levels. Nevertheless, as a result of the inappropriate location of the artificial intercommunication structure of the Juluapan Lagoon with respect to the arrecifal area of study and therefore of the tides influence, other variables, such as the changes in short-term in turbidity, sediment inputs, nutrients, temperature and osmolarity, can act in combination and cause irreversible damage. The implementation of a management plan for the coralline reefs of the Mexican Pacific coast is required.

HYDROBIOLOGICAL CHARACTERISTICS OF THE COASTAL LAGOONS AT HUGH TAYLOR BIRCH STATE RECREATION AREA, FORT LAUDERDALE, FLORIDA: A HISTORICAL PERSPECTIVE.

USGS Publications Warehouse

Brock, Robert J.

1987-01-01

The author presents initial results of an ongoing study of Southeast Florida coastal lagoon lakes. Objectives include presenting environmental conditions within and adjacent to the lagoons under a variety of hydrologic conditions and to determine water-quality changes in ground water and surface water and how these changes in water quality affect lagoonal biological communities within the lagoons.

Metals in some lagoons of Mexico.

PubMed Central

Vazquez, F G; Sharma, V K; Alexander, V H; Frausto, C A

1995-01-01

The concentrations of metals, Cd, Cu, Fe, Mn, Ni, Pb, and Zn were determined in some lagoons to establish the level of metal pollution. The lagoons studied were Alvarado lagoon, Veracruz; San Andres lagoon, Tamaulipas; and Terminos lagoon, Campeche. The concentrations were determined in water, oyster (Crassostrea virginica), and sediments. Metals were accumulated in either oysters or sediments. Cu and Zn were higher in oysters and Fe and Mn were higher in sediments. The results in water samples were compared with the limit established by the Secretaria de Ecologia and Desarrollo Urbano Report and briefly discussed. PMID:7621796

Spatiotemporal variation of bacterial community composition and possible controlling factors in tropical shallow lagoons.

PubMed

Laque, Thaís; Farjalla, Vinicius F; Rosado, Alexandre S; Esteves, Francisco A

2010-05-01

Bacterial community composition (BCC) has been extensively related to specific environmental conditions. Tropical coastal lagoons present great temporal and spatial variation in their limnological conditions, which, in turn, should influence the BCC. Here, we sought for the limnological factors that influence, in space and time, the BCC in tropical coastal lagoons (Rio de Janeiro State, Brazil). The Visgueiro lagoon was sampled monthly for 1 year and eight lagoons were sampled once for temporal and spatial analysis, respectively. BCC was evaluated by bacteria-specific PCR-DGGE methods. Great variations were observed in limnological conditions and BCC on both temporal and spatial scales. Changes in the BCC of Visgueiro lagoon throughout the year were best related to salinity and concentrations of NO (3) (-) , dissolved phosphorus and chlorophyll-a, while changes in BCC between lagoons were best related to salinity and dissolved phosphorus concentration. Salinity has a direct impact on the integrity of the bacterial cell, and it was previously observed that phosphorus is the main limiting nutrient to bacterial growth in these lagoons. Therefore, we conclude that great variations in limnological conditions of coastal lagoons throughout time and space resulted in different BCCs and salinity and nutrient concentration, particularly dissolved phosphorus, are the main limnological factors influencing BCC in these tropical coastal lagoons.

Parasite communities of the neotropical cormorant Phalacrocorax brasilianus (Gmelin) (Aves, Phalacrocoracidae) from two coastal lagoons in Guerrero state, Mexico.

PubMed

Violante-González, Juan; Monks, Scott; Gil-Guerrero, Salvador; Rojas-Herrera, Agustín; Flores-Garza, Rafael; Larumbe-Morán, Edvino

2011-11-01

The parasite community structure of the neotropical cormorant, Phalacrocorax brasilianus, from two lagoons (Coyuca and Tres Palos) from Guerrero state, México, was examined. Fourteen species of adult helminths (6,391 individuals) from 48 cormorants were identified: 9 digeneans, 1 acanthocephalan, 1 cestode, and 3 nematodes. A total of 11 species were collected in Coyuca Lagoon and 12 in Tres Palos Lagoon. Nine species co-occurred in cormorants of both lagoons but, with the exception of Contracaecum multipapillatum and Drepanocephalus olivaceus, species were not equally common in both lagoons. The prevalence values of six species of helminth and the mean abundance of four species varied significantly between lagoons, and C. multipapillatum was numerically dominant in both lagoons. The qualitative similarity between the two communities at the component level was 64%. All cormorants examined were infected, and parasite species richness was 3-5 in Coyuca and 4-9 in Tres Palos lagoon. The results indicate that both communities presented a similar structure at the component level, probably because the cormorants of both lagoons feed on the same species of fish and thus acquire almost the same species of parasites. Differences observed at the infracommunity level were attributed to variations in the degree of dominance of the particular species.

An integrated Pan-European perspective on coastal Lagoons management through a mosaic-DPSIR approach

PubMed Central

Dolbeth, Marina; Stålnacke, Per; Alves, Fátima L.; Sousa, Lisa P.; Gooch, Geoffrey D.; Khokhlov, Valeriy; Tuchkovenko, Yurii; Lloret, Javier; Bielecka, Małgorzata; Różyński, Grzegorz; Soares, João A.; Baggett, Susan; Margonski, Piotr; Chubarenko, Boris V.; Lillebø, Ana I.

2016-01-01

A decision support framework for the management of lagoon ecosystems was tested using four European Lagoons: Ria de Aveiro (Portugal), Mar Menor (Spain), Tyligulskyi Liman (Ukraine) and Vistula Lagoon (Poland/Russia). Our aim was to formulate integrated management recommendations for European lagoons. To achieve this we followed a DPSIR (Drivers-Pressures-State Change-Impacts-Responses) approach, with focus on integrating aspects of human wellbeing, welfare and ecosystem sustainability. The most important drivers in each lagoon were identified, based on information gathered from the lagoons’ stakeholders, complemented by scientific knowledge on each lagoon as seen from a land-sea perspective. The DPSIR cycles for each driver were combined into a mosaic-DPSIR conceptual model to examine the interdependency between the multiple and interacting uses of the lagoon. This framework emphasizes the common links, but also the specificities of responses to drivers and the ecosystem services provided. The information collected was used to formulate recommendations for the sustainable management of lagoons within a Pan-European context. Several common management recommendations were proposed, but specificities were also identified. The study synthesizes the present conditions for the management of lagoons, thus analysing and examining the activities that might be developed in different scenarios, scenarios which facilitate ecosystem protection without compromising future generations. PMID:26776151

Inverse-dispersion technique for assessing lagoon gas emissions

USDA-ARS?s Scientific Manuscript database

Measuring gas emissions from treatment lagoons and storage ponds poses challenging conditions for existing micrometeorological techniques because of non-ideal wind conditions, such as those induced by trees and crops surrounding the lagoons, and lagoons with dimensions too small to establish equilib...

Accuracy of lagoon gas emissions using an inverse dispersion method

USDA-ARS?s Scientific Manuscript database

Measuring gas emissions from treatment lagoons and storage ponds poses challenging conditions for existing micrometeorological techniques because of non-ideal wind conditions. These include those induced by trees and crops surrounding the lagoons, and lagoons with dimensions too small to establish ...

Coastal Processes with Improved Tidal Opening in Chilika Lagoon (east Coast of India)

NASA Astrophysics Data System (ADS)

Jayaraman, Girija; Dube, Anumeha

Chilika Lagoon (19°28-19°54¢N and 85°06-85°36¢E) is the largest brackish water lagoon with estuarine character. Interest in detailed analysis of the ecology of the lagoon and the various factors affecting it is due to the opening of the new mouth on September 23, 2000 to resolve the threat to its environment from various factors - Eutrophication, weed proliferation, siltation, industrial pollution, and depletion of bioresources. The opening of the new mouth has changed the lagoon environment significantly with better socio­economic implications. There is a serious concern if the significant improvement in the biological productivity of the lagoon post-mouth opening is indeed sustainable. The present study focuses on the changes in the coastal processes as a result of the additional opening of a new mouth. Our results based on mathematical modeling and numerical simulation compare the dynamics, nutrient, and plankton distribution before and after the new mouth opening. The model could confirm the significant increase (14-66% depending on the sector) in the salinity after the new mouth opening, the maximum change being observed in the channel which connects the lagoon to the sea. The constriction in the lagoon which blocks the tidal effects entering the lagoon must be responsible for maintaining the main body of the lagoon with low salinity. The ecological model is first tested for different sectors individually before a complete model, including the entire lagoon area, is included incorporating their distinct characteristics. The model is validated with available observations of plankton and nutrients made before the opening of the new mouth. It predicts the annual distribution of plankton in all the sectors of the lagoon for post-mouth opening which is to be verified when the data will be forthcoming.