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Sample records for abstract seagrass beds

  1. Keeping tabs on seagrass beds

    SciTech Connect

    Kuhl, D.E.; Sargent, F.J.; Leary, T.J.

    1997-06-01

    Seagrasses form the foundation of complex, fragile communities that include marine and estuarine animals, especially larval and juvenile fish, providing critical shelter and sustenance. Seagrasses also have a role in providing habitat for waterfowl, marine turtles and manimals. In addition, seagrasses improve water quality by stabilizing mobile sediments and converting some pollutants into plant biomass. The issue of propeller scarring or propeller dredging in seagrass beds has received much attention since 1990. The scarring of seagrass results from personal watercraft. Heightened interest has instigated numerous monitoring and mapping projects on propeller scarring and regrowth characteristics within seagrasses. The study areas selected for this paper are located within Tampa Bay, Florida. Specifically, they are Shell Island and Miquel Bay. Spatial monitoring for the extent of seagrass scarring in the Tampa Bay region was conducted in two ways, a regional (general) approach and a site specific (detailed) approach. Regional monitoring assessed the status of seagrass in Tampa Bay and identified {open_quote}hot spots{close_quote}. After identifying {open_quote}hot spots{close_quote}, boat surveys were used to confirm or deny the initial assessment. This poster involves the design of a propeller scarring monitoring program using several methods: Hi8 video, digital cameras, film cameras, and differential GPS combined with Arcview. A pilot program to evaluate the adequacy of these monitoring devices and the recommendation of specific actions in areas of severe propeller scarring will be presented.

  2. SULFUR CYCLING IN THALASSIA TESTUDINUM SEAGRASS BED SEDIMENTS

    EPA Science Inventory

    Quarles, Robert L., Jessica A. Rivord and Richard Devereux. In press. Sulfur Cycling in Thalassia testudinum Seagrass Bed Sediments (Abstract). To be presented at the SWS/GERS Fall Joint Society Meeting: Communication and Collaboration: Coastal Systems of the Gulf of Mexico and S...

  3. Status and threats on seagrass beds using GIS in Vietnam

    NASA Astrophysics Data System (ADS)

    Luong, Cao Van; Thao, Nguyen Van; Komatsu, Teruhisa; Ve, Nguyen Dac; Tien, Dam Duc

    2012-10-01

    Seagrasses, marine flowering plants, are widely distributed along temperate and tropical coastlines of the world. Seagrasses have key ecological roles in coastal ecosystems and can form extensive meadows supporting high biodiversity. Till now, fourteen seagrass species belonging to four families were found in Vietnam: Halophila beccarii, H. decipiens, H. ovalis, H. minor, Thalassia hemprichii, Enhalus acoroides, Ruppia maritima, Halodule pinifolia, H. uninervis, Syringodium isoetifolium, Cymadocea rotundata, C. serrulata and Thalassodendron ciliatum. A total area of seagrass beds in Vietnam is estimated to be approximately 17000 ha by satellite images and GIS technology. In recent years, the distribution areas and densities of seagrass beds in Vietnam have been serious decreased compared with those 10-15 years ago. The decline level depended on the impacts by the natural process, the economical activities and the conservation awareness of local people. Thus, it is different at each coastal area. Generally speaking, the distribution areas and densities of seagrass beds were decreased by more than 50%. Seagrasses on tidal flats in some areas such as Quang Ninh, Hai Phong, Phu Quoc seem to be nearly lost. The distribution areas of seagrass beds in 2009 at Tam Giang-Cau Hai lagoon and Cua Dai estuary was decreased by 50-70% of those in early 1990s.

  4. Manatee grazing impacts on a mixed species seagrass bed

    USGS Publications Warehouse

    Lefebvre, Lynn W.; Provancha, Jane A.; Slone, Daniel H.; Kenworthy, W. Judson

    2017-01-01

    The endangered manatee Trichechus manatus is one of few large grazers in seagrass systems. To assess the long-term impacts of repeated grazing on seagrasses, we selected a study site within Kennedy Space Center in the northern Banana River, Brevard County, Florida, that was typically grazed by large numbers of manatees in spring. Two 13x13 m manatee exclosures and 2 paired open plots of equal size were established at the study site in October 1990. Shoot counts, biomass, and species composition of the co-dominant seagrass species, Syringodium filiforme and Halodule wrightii, were sampled 3 times per year in all 4 plots between October 1990 and October 1994. We used a Bayesian modelling approach, accounting for the influence of depth, to detect treatment (exclosed vs. open) effects. S. filiforme shoot counts, total biomass, and frequency of occurrence significantly increased in the exclosures. By July 1993, mean biomass values in the exclosures (167 g dry wt m-2) greatly exceeded those in the open plots (28 g dry wt m-2). H. wrightii decreased in the exclosures by 1994. Initially, both S. filiforme and H. wrightii responded positively to release from manatee grazing pressure. As S. filiforme continued to become denser in the exclosures, it gradually replaced H. wrightii. Our findings may be helpful to biologists and managers interested in predicting seagrass recovery and manatee carrying capacity of repeatedly grazed seagrass beds in areas of special significance to manatees and seagrass conservation.

  5. Microbial biomass and productivity in seagrass beds

    NASA Technical Reports Server (NTRS)

    Moriarty, D. J.; Boon, P. I.; Hansen, J. A.; Hunt, W. G.; Poiner, I. R.; Pollard, P. C.; Skyring, G. W.; White, D. C.

    1985-01-01

    Different methods for measuring the rates of processes mediated by bacteria in sediments and the rates of bacterial cell production have been compared. In addition, net production of the seagrass Zostera capricorni and bacterial production have been compared and some interrelationships with the nitrogen cycle discussed. Seagrass productivity was estimated by measuring the plastochrone interval using a leaf stapling technique. The average productivity over four seasons was 1.28 +/- 0.28 g C m-2 day-1 (mean +/- standard deviation, n = 4). Bacterial productivity was measured five times throughout a year using the rate of tritiated thymidine incorporated into DNA. Average values were 33 +/- 12 mg C m-2 day-1 for sediment and 23 +/- 4 for water column (n = 5). Spatial variability between samples was greater than seasonal variation for both seagrass productivity and bacterial productivity. On one occasion, bacterial productivity was measured using the rate of 32P incorporated into phospholipid. The values were comparable to those obtained with tritiated thymidine. The rate of sulfate reduction was 10 mmol SO4(-2) m-2 day-1. The rate of methanogenesis was low, being 5.6 mg CH4 produced m-2 day-1. A comparison of C flux measured using rates of sulfate reduction and DNA synthesis indicated that anaerobic processes were predominant in these sediments. An analysis of microbial biomass and community structure, using techniques of phospholipid analysis, showed that bacteria were predominant members of the microbial biomass and that of these, strictly anaerobic bacteria were the main components. Ammonia concentration in interstitial water varied from 23 to 71 micromoles. Estimates of the amount of ammonia required by seagrass showed that the ammonia would turn over about once per day. Rapid recycling of nitrogen by bacteria and bacterial grazers is probably important.

  6. Diurnal changes in pore water sulfide concentrations in the seagrass Thalassia testudinum beds: the effects of seagrasses on sulfide dynamics.

    PubMed

    Lee; Dunton

    2000-12-20

    The dynamics of the seagrass-sulfide interaction were examined in relation to diel changes in sediment pore water sulfide concentrations in Thalassia testudinum beds and adjacent bare areas in Corpus Christi Bay and lower Laguna Madre, Texas, USA, during July 1996. Pore water sulfide concentrations in seagrass beds were significantly higher than in adjacent bare areas and showed strong diurnal variations; levels significantly decreased during mid-day at shallow sediment depths (0-10 cm) containing high below-ground tissue biomass and surface area. In contrast, diurnal variations in sediment sulfide concentrations were absent in adjacent bare patches, and at deeper (>10 cm) sediment depths characterized by low below-ground plant biomass or when the grasses were experimentally shaded. These observations suggest that the mid-day depressions in sulfide levels are linked to the transport of photosynthetically produced oxygen to seagrass below-ground tissues that fuels sediment sulfide oxidation. Lower sulfide concentrations in bare areas are likely a result of low sulfate reduction rates due to low organic matter available for remineralization. Further, high reoxidation rates due to rapid exchange between anoxic pore water and oxic overlying water are probably stimulated in bare areas by higher current velocity on the sediment surface than in seagrass beds. The dynamics of pore water sulfides in seagrass beds suggest no toxic sulfide intrusion into below-ground tissues during photosynthetic periods and demonstrate that the sediment chemical environment is considerably modified by seagrasses. The reduced sediment sulfide levels in seagrass beds during photosynthetic periods will enhance seagrass production through reduced sulfide toxicity to seagrasses and sediment microorganisms related to the nutrient cycling.

  7. Simulation of seagrass bed mapping by satellite images based on the radiative transfer model

    NASA Astrophysics Data System (ADS)

    Sagawa, Tatsuyuki; Komatsu, Teruhisa

    2015-06-01

    Seagrass and seaweed beds play important roles in coastal marine ecosystems. They are food sources and habitats for many marine organisms, and influence the physical, chemical, and biological environment. They are sensitive to human impacts such as reclamation and pollution. Therefore, their management and preservation are necessary for a healthy coastal environment. Satellite remote sensing is a useful tool for mapping and monitoring seagrass beds. The efficiency of seagrass mapping, seagrass bed classification in particular, has been evaluated by mapping accuracy using an error matrix. However, mapping accuracies are influenced by coastal environments such as seawater transparency, bathymetry, and substrate type. Coastal management requires sufficient accuracy and an understanding of mapping limitations for monitoring coastal habitats including seagrass beds. Previous studies are mainly based on case studies in specific regions and seasons. Extensive data are required to generalise assessments of classification accuracy from case studies, which has proven difficult. This study aims to build a simulator based on a radiative transfer model to produce modelled satellite images and assess the visual detectability of seagrass beds under different transparencies and seagrass coverages, as well as to examine mapping limitations and classification accuracy. Our simulations led to the development of a model of water transparency and the mapping of depth limits and indicated the possibility for seagrass density mapping under certain ideal conditions. The results show that modelling satellite images is useful in evaluating the accuracy of classification and that establishing seagrass bed monitoring by remote sensing is a reliable tool.

  8. Mapping seagrass beds and coral reefs in the coastal region of Vietnam using VNREDSAT-1 data

    NASA Astrophysics Data System (ADS)

    Lau, K. V.; Chen, C. F.; Nguyen, S. T.; Chen, C. R.; Tong Phuoc, H. S.; Nguyen, H. H.

    2015-12-01

    Seagrass beds and coral reefs are two important ecosystems in the coastal zone. They play an important role to protect and shelter various marine organisms. Both seagrass beds and coral reefs could prevent the coastline from erosion. While seagrass stabilizes sediments and acts as a biofilter, coral reefs can control carbon dioxide in the ocean water. Besides, seagrass also provides direct food for many fish and marine animals. Therefore, mapping seagrass beds and coral reefs is very important for coastal management and conservation. In May 2013, Vietnam launched the first satellite for earth observations, called Vietnam Natural Resources, Environment and Disaster Monitoring Satellite (VNREDSAT-1). It is a great opportunity for environmental monitoring in the country using the data from this satellite. The objective of this study is to use the VNREDSAT-1 data to map seagrass beds and coral reefs in the coastal region of Ninh Hai district, Ninh Thuan province, Vietnam, where the seagrass still remains in good a condition. We processed the VNREDSAT-1 image through four steps: (1) Atmospheric correction using Second Simulation of the Satellite Signal in the Solar Spectrum radiative transfer model (6S), (2) Sun glint removal by using Hedley method, (3) Water column correction using the depth-variant index (DII) proposed by Lyzenga, and (4) Image classification using the maximum likelihood algorithm. The mapping results verified with the ground reference data showed a good overall accuracy of 75% and Kappa coefficient of 0.7. The total area of seagrass beds was approximately 323.09 ha, which mainly distributed in My Hoa and Thai An villages. The total area of coral reefs was approximately 564.42 ha, located along the coast and on outer area to seagrass and shoreline reefs. This study demonstrates the applicability of VNREDSAT-1 for underwater habitat monitoring. The results could be useful for natural resources managers to devise strategies for management and

  9. The effects of sea urchin grazing and drift algal blooms on a subtropical seagrass bed community.

    PubMed

    Maciá

    2000-03-30

    Subtropical seagrass beds can be subject to relatively high levels of direct herbivory and large blooms of drift algae, both of which can have important effects on the floral and faunal components of the community. Caging experiments were used to investigate these factors in a Thalassia testudinum bed in Biscayne Bay, Florida. Abundance of sea urchins, Lytechinus variegatus, and drift algae was manipulated within the cages. Naturally occurring levels of urchin grazing do not appear to affect the T. testudinum population. With experimentally increased urchin densities in the winter, seagrass shoot density and aboveground biomass decreased significantly. Similar effects were not detected in the summer, indicating that the impact of grazing on T. testudinum is lessened during this time of year. Shoot density was more vulnerable to grazing than aboveground biomass. This may be a result of grazing-induced increases in seagrass productivity, in which the remaining shoots produce more or longer leaves. In the winter, drift algal blooms form large mats that cover the seagrass canopy. Under the normal grazing regime these algal blooms do not have significant negative effects on the seagrass. With increased grazing pressure, however, there is a synergistic effect of grazing and drift algae on seagrass shoot density. At intermediate urchin density (10 per m(-2)), cages without algae did not undergo significant decreases in shoot density, while those with algae did. At the high density of urchins, the number of seagrass shoots in cages both with and without algae decreased, but the effect was more pronounced for cages with algae. Invertebrate abundance at the field site was low relative to other seagrass beds. There were no discernible effects, either positive or negative, of urchin and algae manipulations on the sampled invertebrate community.

  10. Quantifying Seagrass Light Requirements Using an Algorithm to Spatially Resolve Depth of Colonization-Conf Abstract

    EPA Science Inventory

    Depth of colonization (Zc) is a useful seagrass growth metric that describes seagrass response to light attenuation. Similarly, percent surface irradiance (% SI) at Zc is a measure of seagrass light requirements with applications in seagrass ecology and management. Methods for ...

  11. Low-canopy seagrass beds still provide important coastal protection services.

    PubMed

    Christianen, Marjolijn J A; van Belzen, Jim; Herman, Peter M J; van Katwijk, Marieke M; Lamers, Leon P M; van Leent, Peter J M; Bouma, Tjeerd J

    2013-01-01

    One of the most frequently quoted ecosystem services of seagrass meadows is their value for coastal protection. Many studies emphasize the role of above-ground shoots in attenuating waves, enhancing sedimentation and preventing erosion. This raises the question if short-leaved, low density (grazed) seagrass meadows with most of their biomass in belowground tissues can also stabilize sediments. We examined this by combining manipulative field experiments and wave measurements along a typical tropical reef flat where green turtles intensively graze upon the seagrass canopy. We experimentally manipulated wave energy and grazing intensity along a transect perpendicular to the beach, and compared sediment bed level change between vegetated and experimentally created bare plots at three distances from the beach. Our experiments showed that i) even the short-leaved, low-biomass and heavily-grazed seagrass vegetation reduced wave-induced sediment erosion up to threefold, and ii) that erosion was a function of location along the vegetated reef flat. Where other studies stress the importance of the seagrass canopy for shoreline protection, our study on open, low-biomass and heavily grazed seagrass beds strongly suggests that belowground biomass also has a major effect on the immobilization of sediment. These results imply that, compared to shallow unvegetated nearshore reef flats, the presence of a short, low-biomass seagrass meadow maintains a higher bed level, attenuating waves before reaching the beach and hence lowering beach erosion rates. We propose that the sole use of aboveground biomass as a proxy for valuing coastal protection services should be reconsidered.

  12. Low-Canopy Seagrass Beds Still Provide Important Coastal Protection Services

    PubMed Central

    Christianen, Marjolijn J. A.; van Belzen, Jim; Herman, Peter M. J.; van Katwijk, Marieke M.; Lamers, Leon P. M.; van Leent, Peter J. M.; Bouma, Tjeerd J.

    2013-01-01

    One of the most frequently quoted ecosystem services of seagrass meadows is their value for coastal protection. Many studies emphasize the role of above-ground shoots in attenuating waves, enhancing sedimentation and preventing erosion. This raises the question if short-leaved, low density (grazed) seagrass meadows with most of their biomass in belowground tissues can also stabilize sediments. We examined this by combining manipulative field experiments and wave measurements along a typical tropical reef flat where green turtles intensively graze upon the seagrass canopy. We experimentally manipulated wave energy and grazing intensity along a transect perpendicular to the beach, and compared sediment bed level change between vegetated and experimentally created bare plots at three distances from the beach. Our experiments showed that i) even the short-leaved, low-biomass and heavily-grazed seagrass vegetation reduced wave-induced sediment erosion up to threefold, and ii) that erosion was a function of location along the vegetated reef flat. Where other studies stress the importance of the seagrass canopy for shoreline protection, our study on open, low-biomass and heavily grazed seagrass beds strongly suggests that belowground biomass also has a major effect on the immobilization of sediment. These results imply that, compared to shallow unvegetated nearshore reef flats, the presence of a short, low-biomass seagrass meadow maintains a higher bed level, attenuating waves before reaching the beach and hence lowering beach erosion rates. We propose that the sole use of aboveground biomass as a proxy for valuing coastal protection services should be reconsidered. PMID:23723969

  13. Diel trophic structuring of seagrass bed fish assemblages in the Wakatobi Marine National Park, Indonesia

    NASA Astrophysics Data System (ADS)

    Unsworth, Richard K. F.; Wylie, Elizabeth; Smith, David J.; Bell, James J.

    2007-03-01

    The faunal communities of seagrass beds throughout SE Asia are highly threatened by continued overexploitation, yet their ecology is poorly understood. Developing a greater understanding of the faunal linkages between seagrass beds and associated coastal habitats can facilitate more informed ecosystem level management. The present study used beach seine netting to sample seagrass bed fish assemblages in the Wakatobi Marine National Park, Indonesia, to investigate diel migrations of fish into and out of seagrass beds. These fish assemblages were found to be diverse relative to other studies within the region, with many species being economically important to local subsistence fisheries. The abundance, species richness and trophic structure of these fish assemblages changed with time of day indicating that fish populations are in a dynamic state. Mean fish abundance increased by ≈45% from day to night (Day: 8.61 ± 0.13 fish 100 m -2; Night: 15.6 ± 1.4 fish 100 m -2) while mean species richness increased from 6.6 ± 1.9 per seine haul to 11.4 ± 0.2. Increasing abundance and diversity of fish at night suggests migration onto these habitats from nearby habitats such as reefs, mangroves or deep water; and/or increased activity of those fish resident within seagrass habitats. Division of species into trophic categories enabled the trophic structure of changing fish assemblages to be examined. Assemblages were dominated during both the day and night by invertebrate and fish feeders; however, a major diel change in trophic structure occurred in the abundance of omnivores. During the day omnivores were abundant, but they were replaced at night by exclusive invertebrate feeders. We therefore propose that diel changes in seagrass fish assemblages are predominantly structured by food availability, although other factors such as increased night-time shelter provision were also found to be important albeit to a much lesser extent.

  14. Mapping spatial resources with GPS animal telemetry: foraging manatees locate seagrass beds in the Ten Thousand Islands, Florida, USA

    USGS Publications Warehouse

    Slone, Daniel H.; Reid, James P.; Kenworthy, W. Judson

    2013-01-01

    Turbid water conditions make the delineation and characterization of benthic habitats difficult by traditional in situ and remote sensing methods. Here, we develop and validate modeling and sampling methodology for detecting and characterizing seagrass beds by analyzing GPS telemetry records from radio-tagged manatees. Between October 2002 and October 2005, 14 manatees were tracked in the Ten Thousand Islands (TTI) in southwest Florida (USA) using Global Positioning System (GPS) tags. High density manatee use areas were found to occur off each island facing the open, nearshore waters of the Gulf of Mexico. We implemented a spatially stratified random sampling plan and used a camera-based sampling technique to observe and record bottom observations of seagrass and macroalgae presence and abundance. Five species of seagrass were identified in our study area: Halodule wrightii, Thalassia testudinum, Syringodium filiforme, Halophila engelmannii, and Halophila decipiens. A Bayesian model was developed to choose and parameterize a spatial process function that would describe the observed patterns of seagrass and macroalgae. The seagrasses were found in depths <2 m and in the higher manatee use strata, whereas macroalgae was found at moderate densities at all sampled depths and manatee use strata. The manatee spatial data showed a strong association with seagrass beds, a relationship that increased seagrass sampling efficiency. Our camera-based field sampling proved to be effective for assessing seagrass density and spatial coverage under turbid water conditions, and would be an effective monitoring tool to detect changes in seagrass beds.

  15. Detection of seagrass beds in Khunk Graben Bay, Thailand, using ALOS AVNI2 image

    NASA Astrophysics Data System (ADS)

    Komatsu, Teruhisa; Noiraksar, Thidarat; Sakamoto, Shingo X.; Sawayama, Shuhei; Miyamoto, Hiroomi; Phauk, Sophany; Thongdee, Pornthep; Jualaong, Suthep; Nishida, Shuhei

    2012-11-01

    Coastal habitats having high productivity provide numerous ecological services such as foods, protection from strong waves through buffering effect, fixation of CO2 through photosynthesis, fostering biodiversity etc. However, increasing human impacts and climate change decrease or degrade coastal habitats. ASEAN region is developing most rapidly in the world. In the developing region, it is necessary to grasp present spatial distributions of habitats as a baseline data with standardized mapping methods. Remote sensing is one of the most effective methods for mapping. Japan Aerospace Exploration Agency (JAXA) provides non-commercial satellite images with ultra-high spatial resolution optical sensors (10 m), AVNIR2, similar to LANDSAT TM. Using ALOS AVNIR2 images it may be possible to make habitat map in the region. In Thailand, shrimp ponds cause degradation of coastal ecosystem through cutting mangroves and eutrophicated discharge from ponds. We examined capability of remote sesing with ALOS AVNIR2 to map seagrass beds in Khung Kraben Bay, Chanthaburi Province, Thailand, surrounded by shrimp ponds. We analyzed ALOS AVNIR2 taken on 25 January 2008. Ground truth survey was conducted in October 2010 using side scan sonar and scuba diving. The survey revealed that there were broad seagrass beds consisting of Enhalus acroides. We used a decision tree to detect seagrass beds in the bay with quite turbid seawater coupled with Depth-Invariant Index proposed by Lyzenga (1985) and bottom reflectances. We could succeed to detect seagrass beds. Thus it is concluded that ALOS AVNIR2 is practical to map seagrass beds in this region.

  16. Tiny is mighty: seagrass beds have a large role in the export of organic material in the tropical coastal zone.

    PubMed

    Gillis, Lucy G; Ziegler, Alan D; van Oevelen, Dick; Cathalot, Cecile; Herman, Peter M J; Wolters, Jan W; Bouma, Tjeerd J

    2014-01-01

    Ecosystems in the tropical coastal zone exchange particulate organic matter (POM) with adjacent systems, but differences in this function among ecosystems remain poorly quantified. Seagrass beds are often a relatively small section of this coastal zone, but have a potentially much larger ecological influence than suggested by their surface area. Using stable isotopes as tracers of oceanic, terrestrial, mangrove and seagrass sources, we investigated the origin of particulate organic matter in nine mangrove bays around the island of Phuket (Thailand). We used a linear mixing model based on bulk organic carbon, total nitrogen and δ13C and δ15N and found that oceanic sources dominated suspended particulate organic matter samples along the mangrove-seagrass-ocean gradient. Sediment trap samples showed contributions from four sources oceanic, mangrove forest/terrestrial and seagrass beds where oceanic had the strongest contribution and seagrass beds the smallest. Based on ecosystem area, however, the contribution of suspended particulate organic matter derived from seagrass beds was disproportionally high, relative to the entire area occupied by mangrove forests, the catchment area (terrestrial) and seagrass beds. The contribution from mangrove forests was approximately equal to their surface area, whereas terrestrial contributions to suspended organic matter under contributed compared to their relative catchment area. Interestingly, mangrove forest contribution at 0 m on the transects showed a positive relationship with the exposed frontal width of the mangrove, indicating that mangrove forest exposure to hydrodynamic energy may be a controlling factor in mangrove outwelling. However we found no relationship between seagrass bed contribution and any physical factors, which we measured. Our results indicate that although seagrass beds occupy a relatively small area of the coastal zone, their role in the export of organic matter is disproportional and should be

  17. Tiny Is Mighty: Seagrass Beds Have a Large Role in the Export of Organic Material in the Tropical Coastal Zone

    PubMed Central

    Gillis, Lucy G.; Ziegler, Alan D.; van Oevelen, Dick; Cathalot, Cecile; Herman, Peter M. J.; Wolters, Jan W.; Bouma, Tjeerd J.

    2014-01-01

    Ecosystems in the tropical coastal zone exchange particulate organic matter (POM) with adjacent systems, but differences in this function among ecosystems remain poorly quantified. Seagrass beds are often a relatively small section of this coastal zone, but have a potentially much larger ecological influence than suggested by their surface area. Using stable isotopes as tracers of oceanic, terrestrial, mangrove and seagrass sources, we investigated the origin of particulate organic matter in nine mangrove bays around the island of Phuket (Thailand). We used a linear mixing model based on bulk organic carbon, total nitrogen and δ13C and δ15N and found that oceanic sources dominated suspended particulate organic matter samples along the mangrove-seagrass-ocean gradient. Sediment trap samples showed contributions from four sources oceanic, mangrove forest/terrestrial and seagrass beds where oceanic had the strongest contribution and seagrass beds the smallest. Based on ecosystem area, however, the contribution of suspended particulate organic matter derived from seagrass beds was disproportionally high, relative to the entire area occupied by mangrove forests, the catchment area (terrestrial) and seagrass beds. The contribution from mangrove forests was approximately equal to their surface area, whereas terrestrial contributions to suspended organic matter under contributed compared to their relative catchment area. Interestingly, mangrove forest contribution at 0 m on the transects showed a positive relationship with the exposed frontal width of the mangrove, indicating that mangrove forest exposure to hydrodynamic energy may be a controlling factor in mangrove outwelling. However we found no relationship between seagrass bed contribution and any physical factors, which we measured. Our results indicate that although seagrass beds occupy a relatively small area of the coastal zone, their role in the export of organic matter is disproportional and should be

  18. Habitat fragmentation has some impacts on aspects of ecosystem functioning in a sub-tropical seagrass bed.

    PubMed

    Sweatman, Jennifer L; Layman, Craig A; Fourqurean, James W

    2017-05-01

    Habitat fragmentation impacts ecosystem functioning in many ways, including reducing the availability of suitable habitat for animals and altering resource dynamics. Fragmentation in seagrass ecosystems caused by propeller scarring is a major source of habitat loss, but little is known about how scars impact ecosystem functioning. Propeller scars were simulated in seagrass beds of Abaco, Bahamas, to explore potential impacts. To determine if plant-herbivore interactions were altered by fragmentation, amphipod grazers were excluded from half the experimental plots, and epiphyte biomass and community composition were compared between grazer control and exclusion plots. We found a shift from light limitation to phosphorus limitation at seagrass patch edges. Fragmentation did not impact top-down control on epiphyte biomass or community composition, despite reduced amphipod density in fragmented habitats. Seagrass and amphipod responses to propeller scarring suggest that severely scarred seagrass beds could be subject to changes in internal nutrient stores and amphipod distribution.

  19. Effects of herbivorous birds on intertidal seagrass beds in the northern Wadden Sea

    NASA Astrophysics Data System (ADS)

    Nacken, M.; Reise, K.

    2000-07-01

    During autumn migration (September to December), brent geese (Branta b. bernicla) and wigeon (Anas penelope) feed on the seagrass Zostera noltii in the nearshore, upper tidal zone leeward of the island of Sylt (eastern North Sea). To graze on leaves and shoots above the sediment and on rhizomes and roots below, these birds reworked the entire upper 1 cm layer of sediment eight times within this 3-month period. In addition, brent geese excavated pits 3-10 cm deep by trampling in order to feed on below-ground phytomass. About 12% of the seagrass beds became pitted to an average depth of 4.5 cm. Using net exclosures, it was estimated that birds removed 34 g dry weight m-2 of above-ground and 28 g of below-ground phytomass. This corresponds to 45% of the phytomass in September. Of the overall loss of phytomass from September to December, 63% was caused by birds. Roughly half of the leaves fell off anyway until December and the other half were taken by the birds. Below the ground, phytomass remained almost constant where birds were excluded, while with birds phytomass of rhizomes and roots was halved. In spite of this strong effect, in the next vegetation period the blade density was lower at former exclosure sites compared to the ambient seagrass bed. The underlying process seems to be a self-inhibition of dense overwintering seagrass by mud accretion. Assuming our experimental results can be scaled up to the entire seagrass bed, we hypothesize that in the sheltered upper intertidal zone, seasonal erosion caused by herbivorous geese and ducks is necessary for the persistence of Z. noltii.

  20. Abrupt transitions between macrobenthic faunal assemblages across seagrass bed margins

    NASA Astrophysics Data System (ADS)

    Barnes, R. S. K.; Hamylton, S.

    2013-10-01

    The nature of the transition from one contrasting macrobenthic assemblage to another across interfaces between intertidal seagrass and unvegetated sand was investigated in the subtropical Moreton Bay Marine Park, eastern Australia, via six two-dimensional core lattices. The same pattern of transition was manifested in each lattice. Macrofaunal abundance, species density (both observed and estimated total) and assemblage composition did not vary with distance away from the interface within the 0.75 m wide marginal bands of each habitat type. Neither were there significant differences in assemblage metrics or composition between the marginal and non-edge regions of either habitat. There were, however, very marked differences in assemblage composition, abundance and species density across the 25 cm wide strip on either side of the actual interface, the interacting assemblages reacting symmetrically. All these differences therefore took place over an ecotone distance of only 0.5 m at most. Spatial trends in assemblage metrics across the boundary zone were captured accurately by second and third order polynomial regression models. It also appeared that edge effects on individual species within the seagrass were a variable local response not a consistent effect of closeness to the bare sand.

  1. Level of contamination by metallic trace elements and organic molecules in the seagrass beds of Guadeloupe Island.

    PubMed

    Bouchon, Claude; Lemoine, Soazig; Dromard, Charlotte; Bouchon-Navaro, Yolande

    2016-01-01

    Seagrass bed ecosystems occupy the most important part of coastal shelf in the French West Indies. They also constitute nurseries for many invertebrates and fishes harvested by local fisheries. In Guadeloupe, coastal fish stocks are declining meanwhile several agroecosystems revealed to be heavily contaminated by pollutants (agricultural lands, rivers, mangroves, seagrass beds, and coral reefs). Considering these facts, a study of the contamination of seagrass beds (8000 ha) of the Grand Cul-de-Sac Marin (GCSM) bay was conducted on their sediments and marine phanerogams. The analyses concerned six metals (Cd, Cu, Hg, Pb, V, Zn), tributyltin, 18 polycyclic aromatic hydrocarbons (PAHs), eight polybrominated diphenyl ethers (PBDEs), 38 polychlorobiphenyls (PCBs), dithiocarbamates (CS2 residues), and 225 pesticide molecules.Overall, the level of contamination of the seagrass beds was low for both sediments and phanerogams. Metallic trace elements were the main pollutants but with higher concentrations recorded in coastal sites, and their distribution can be explained by the proximity of river mouths and current patterns. The level of contamination was lower in plants than in sediments. However, the level of contamination between these two compartments was significantly correlated. The conclusion of this study is that, unlike other coastal ecosystems of Guadeloupe such as mangroves, the seagrass beds in the GCSM present a low degree of pollution. The observed level of contaminants does not seem to threaten the role of nursery played by the seagrass beds and does not likely present a risk for the reintroduction of manatees.

  2. Carbon and nitrogen stable isotope analysis of an Amphibolis griffithii seagrass bed

    NASA Astrophysics Data System (ADS)

    Smit, A. J.; Brearley, A.; Hyndes, G. A.; Lavery, P. S.; Walker, D. I.

    2005-11-01

    Western Australia has a rich diversity of seagrasses, many of which are meadow-forming species with a high diversity of associated epiphytes. Potential food sources and dominant invertebrates and fishes were collected in a non-quantitative sampling programme designed to examine the variability in naturally occurring isotopes ( 13C/ 12C and 15N/ 14N) within an Amphibolis griffithii dominated seagrass bed in Western Australia. The aims of this study were to determine the isotopic composition of the organisms, and to determine the sources of carbon available to consumers using the variations in the ratio of 15N/ 14N and 13C/ 12C among organisms in the seagrass assemblage. Autotrophs showed a wide distribution of δ13C values, with seagrass material significantly enriched in 13C relative to macroalgal sources by >10‰. This variation allowed us to successfully identify macroalgae as the main contributor of carbon to the trophic structure. δ15N ratios did not vary to the degree that would make it useful as tracer, but it was applied to estimating the total number of trophic transfers of nitrogen. Analysis of δ15N values suggested that four trophic positions were present, with fishes ( Acanthaluteres vittiger, Scobonichthys granulatus and Siphonognathus radiatus, Pelsartia humeralis, Pelates sexlineatus, Leviprora inops, Odax acroptilus and Notolabrus parilus) occupying the top two levels. δ13C of seston (20-200 μm) and sedimentary organic matter indicate that seagrass material is the main contributor to these two carbon pools, and that very little of it is incorporated into the trophic structure.

  3. Material exchange and food web of seagrass beds in the Sylt-Rømø Bight: how significant are community changes at the ecosystem level?

    NASA Astrophysics Data System (ADS)

    Asmus, H.; Asmus, R.

    2000-07-01

    Material exchange, biodiversity and trophic transfer within the food web were investigated in two different types of intertidal seagrass beds: a sheltered, dense Zostera marina bed and a more exposed, sparse Z. noltii bed, in the Northern Wadden Sea. Both types of Zostera beds show a seasonal development of above-ground biomass, and therefore measurements were carried out during the vegetation period in summer. The exchange of particles and nutrients between seagrass beds and the overlying water was measured directly using an in situ flume. Particle sedimentation [carbon (C), nitrogen (N) and phosphorus (P) constituents] from the water column prevailed in dense seagrass beds. In the sheltered, dense seagrass bed, a net particle uptake was found even on windy days (7-8 Beaufort). Dissolved inorganic N and orthophosphate were mainly taken up by the dense seagrass bed. At times of strong winds, nutrients were released from the benthic community to tidal waters. In a budget calculation of total N and total P, the dense seagrass beds were characterised as a material sink. The seagrass beds with sparse Z. noltii were a source of particles even during calm weather. The uptake of dissolved inorganic N in the sparse seagrass bed was low but significant, while the uptake of inorganic phosphate and silicate by seagrasses and their epiphytes was exceeded by release processes from the sediment into the overlying water. Estimates at the ecosystem level showed that material fluxes of seagrass beds in the Sylt-Rømø Bight are dominated by the dense type of Zostera beds. Therefore, seagrass beds act as a sink for particles and for dissolved inorganic nutrients. During storms, seagrass beds are distinct sources for inorganic nutrients. The total intertidal area of the Sylt-Rømø Bight could be described as a sink for particles and a source for dissolved nutrients. This balance of the material budget was estimated by either including or excluding seagrass beds. Including the

  4. Effects of seagrass bed removal for tourism purposes in a Mauritian bay.

    PubMed

    Daby, D

    2003-01-01

    Stresses and shocks are increasing on the main natural assets in Mauritius (Western Indian Ocean) by tourism (marine-based) development activities. Seagrasses are removed by hotels in the belief that they are unsightly or harbour organisms causing injury to bathers. Environmental changes (e.g. sediment characteristics and infauna distribution, water quality, seagrass biomass) resulting from clearing of a seagrass bed to create an aesthetically pleasant swimming zone for clients of a hotel were monitored during June 2000-July 2001, and compared to conditions prevailing in an adjacent undisturbed area. Key observations in the disturbed area were: highly turbid water overlying a destabilized lagoon seabed, complete loss of sediment infauna, and dramatic dry weight biomass declines (e.g. 72 and 65% in S. isoetifolium and H. uninervis, respectively). Such disruptions draw-down resilience rendering the marine habitats less robust and more vulnerable to environmental change and extreme events, with higher risks of chaos and ecological collapse, and constitute a major threat to the industry itself.

  5. A one-century suite of seagrass bed maps: can we trust ancient maps?

    NASA Astrophysics Data System (ADS)

    Leriche, Agathe; Boudouresque, Charles-François; Bernard, Guillaume; Bonhomme, Patrick; Denis, Jacques

    2004-02-01

    To assess the dynamics of seagrass beds, it is necessary to be able to compare their present day and former distribution patterns. In most cases, ancient data are available in the form of maps whose reliability must be estimated before comparison. In the study area (near Marseilles, France), a series of maps of the seagrass Posidonia oceanica beds spanning more than one century (dating from 1883, 1897, 1958, 1975, 1979, 1991 and 2000, respectively) are available. In addition, a new map was established, using aerial photography (shallow areas), side scan sonar (deeper areas) and data validation by ground truth. In order to help assess the value of the ancient maps, a Reliability Index (RI) is proposed. The RI, rated from 0 to 50, weighs three parameters: (i) the initial scale of the map (source map) and the working scale (target map); (ii) the method of data acquisition (e.g. dredges, grabs, aerial photography, side scan sonar, scuba diving); and (iii) the method of data georeferencing. Dramatic differences in the distribution of seagrass beds are apparent between the eight maps. In view of the biological features of P. oceanica (e.g. slow rate of change of the meadow limits under natural conditions and the persistence of rhizomes after its death), it is possible that some of these differences may not reflect change over time but may be due to errors in the ancient maps. In contrast, other differences are plausible and validated by field data, e.g. the regression of the lower limit of the meadow. It was thus possible to compare the calculated RI for each map and the plausibility of observed differences as a basis for calibrating the RI.

  6. Caribbean-Wide, Long-Term Study of Seagrass Beds Reveals Local Variations, Shifts in Community Structure and Occasional Collapse

    PubMed Central

    van Tussenbroek, Brigitta I.; Cortés, Jorge; Collin, Rachel; Fonseca, Ana C.; Gayle, Peter M. H.; Guzmán, Hector M.; Jácome, Gabriel E.; Juman, Rahanna; Koltes, Karen H.; Oxenford, Hazel A.; Rodríguez-Ramirez, Alberto; Samper-Villarreal, Jimena; Smith, Struan R.; Tschirky, John J.; Weil, Ernesto

    2014-01-01

    The CARICOMP monitoring network gathered standardized data from 52 seagrass sampling stations at 22 sites (mostly Thalassia testudinum-dominated beds in reef systems) across the Wider Caribbean twice a year over the period 1993 to 2007 (and in some cases up to 2012). Wide variations in community total biomass (285 to >2000 g dry m−2) and annual foliar productivity of the dominant seagrass T. testudinum (<200 and >2000 g dry m−2) were found among sites. Solar-cycle related intra-annual variations in T. testudinum leaf productivity were detected at latitudes > 16°N. Hurricanes had little to no long-term effects on these well-developed seagrass communities, except for 1 station, where the vegetation was lost by burial below ∼1 m sand. At two sites (5 stations), the seagrass beds collapsed due to excessive grazing by turtles or sea-urchins (the latter in combination with human impact and storms). The low-cost methods of this regional-scale monitoring program were sufficient to detect long-term shifts in the communities, and fifteen (43%) out of 35 long-term monitoring stations (at 17 sites) showed trends in seagrass communities consistent with expected changes under environmental deterioration. PMID:24594732

  7. Caribbean-wide, long-term study of seagrass beds reveals local variations, shifts in community structure and occasional collapse.

    PubMed

    van Tussenbroek, Brigitta I; Cortés, Jorge; Collin, Rachel; Fonseca, Ana C; Gayle, Peter M H; Guzmán, Hector M; Jácome, Gabriel E; Juman, Rahanna; Koltes, Karen H; Oxenford, Hazel A; Rodríguez-Ramirez, Alberto; Samper-Villarreal, Jimena; Smith, Struan R; Tschirky, John J; Weil, Ernesto

    2014-01-01

    The CARICOMP monitoring network gathered standardized data from 52 seagrass sampling stations at 22 sites (mostly Thalassia testudinum-dominated beds in reef systems) across the Wider Caribbean twice a year over the period 1993 to 2007 (and in some cases up to 2012). Wide variations in community total biomass (285 to >2000 g dry m(-2)) and annual foliar productivity of the dominant seagrass T. testudinum (<200 and >2000 g dry m(-2)) were found among sites. Solar-cycle related intra-annual variations in T. testudinum leaf productivity were detected at latitudes > 16°N. Hurricanes had little to no long-term effects on these well-developed seagrass communities, except for 1 station, where the vegetation was lost by burial below ∼1 m sand. At two sites (5 stations), the seagrass beds collapsed due to excessive grazing by turtles or sea-urchins (the latter in combination with human impact and storms). The low-cost methods of this regional-scale monitoring program were sufficient to detect long-term shifts in the communities, and fifteen (43%) out of 35 long-term monitoring stations (at 17 sites) showed trends in seagrass communities consistent with expected changes under environmental deterioration.

  8. Preliminary study of mysid community on seagrass bed of Pulau Tinggi, Johor

    NASA Astrophysics Data System (ADS)

    Siang, Tan Hai; Rahim, Azman Abdul; Ross, Othman Haji

    2015-09-01

    This study aims to elucidate the abundance and species composition of the mysid community from seagrass bed of Pulau Tinggi. Samples were taken from July 2009 until October 2009 excluding September 2009 by using epibenthic sledge from Kampung Pasir Panjang and Kampug Sebirah Kecil. A greater abundance of mysids occurred in the seagrass area of Kampung Pasir Panjang (69.10%) compared to the Kampung Sebirah Kecil (30.90%). Maximum mysid abundance occurred during October at both study sites for the whole study period. A total of 1136 mysid individuals comprising 14 species from 5 subfamilies were identified. They were Erythrops minuta Hansen, 1910, Anchialina dentata Pillai, 1964, Haplostylus bengalensis (Hansen, 1910), Haplostylus sp. 1, Haplostylus sp. 2, Pseudanchialina inermis (Illig, 1906), Prionomysis aspera Ii, 1937, Acanthomysis longispina Fukuoka & Murano, 2002, Acanthomysis platycauda (Pillai, 1961), Acanthomysis quadrispinosa Nouvel, 1965, Anisomysis aikawai Ii, 1964, Lycomysis spinicauda Hansen, 1910 and Siriella vulgaris Hansen, 1910. Maximum species richness occurred in the Kampung Sebirah Kecil (10) during July 2009 followed by October 2009 (9) and August 2009 (8) while for Kampung Pasir Panjang highest species richness occurred during October 2009 (8), July 2009 (7) and August 2009 (6). Siriella vulgaris was the most dominant species consisting 41.20% (195ind/m3) of the total mysids sampled.

  9. Temporal changes in benthic communities of seagrass beds impacted by a tsunami in the Andaman Sea, Thailand

    NASA Astrophysics Data System (ADS)

    Whanpetch, Napakhwan; Nakaoka, Masahiro; Mukai, Hiroshi; Suzuki, Takao; Nojima, Satoshi; Kawai, Takashi; Aryuthaka, Chittima

    2010-04-01

    Seagrass beds are susceptible to various natural and human-induced disturbances. Disturbances affect not only seagrasses, but also the abundance and diversity of associated macrofaunal communities. The Andaman Sea coast of Thailand was heavily affected by the tsunami of December 26, 2004. To examine its impact on seagrass macrofaunal communities, we compared the abundance, diversity and taxa composition by quantitative samplings in 2001 (before the tsunami) and in 2005 and 2006 (after the tsunami). Macrobenthic animals and sediments were collected from vegetated and nonvegetated areas of two sites that had received different levels of tsunami disturbances. A large decline in abundance and diversity was observed in the nonvegetated areas after the tsunami, whereas an increase was observed in the vegetated areas. The magnitude of decline and subsequent recovery of abundance and diversity of macrobenthic animals in nonvegetated areas were similar between the two sites, suggesting that their temporal changes were not solely related to the magnitude of the tsunami disturbance. Similarity of the benthic animals differed greatly between 2001 and 2005-2006 at the nonvegetated areas, whereas it varied less among the 3 years at the seagrass-vegetated areas. This study demonstrated that the presence of seagrass vegetation alters the patterns of temporal variation in macrofaunal assemblages and subsequent recovery processes following a tsunami.

  10. ANALYSIS OF BACTERIAL COMMUNITIES IN SEAGRASS BED SEDIMENTS BY DOUBLE-GRADIENT DENATURING GRADIENT GEL ELECTROPHORESIS OF PCR-AMPLIFIED 16SRRNA GENES

    EPA Science Inventory

    Bacterial communities associated with seagrass bed sediments are not well studied. The work presented here investigated several factors, including the presence or absence of vegetation, depth into sediment, and season, and their impact on bacterial community diversity. Double gra...

  11. Stocks and sources of carbon buried in the salt marshes and seagrass beds of Patos Lagoon Estuary, Southern Brazil

    NASA Astrophysics Data System (ADS)

    Patterson, Elizabeth; Johnson, Beverly; Dostie, Philip; Copertino, Margareth

    2016-04-01

    This project investigates carbon stocks in salt marshes and seagrass beds in the Patos Lagoon estuary, the largest choked lagoon in the world, located in Southern Brazil. The study was conducted in the mesohaline region, at three shallow shoals. At each shoal, three sediment cores (50 cm deep) and plant biomass samples (above and belowground) were collected along a transect line, spanning from the marsh to seagrass beds (total = 9 sediment cores). The 50cm cores were subsampled and analyzed for organic carbon (C) and nitrogen (N) content, C/N ratios, and the isotope ratios of 13C/12C, and 15N/14N. The organic carbon content of these sediments ranged between 10% (in surface sediments) and 1% (deeper in the core), suggesting that both the salt marshes and seagrass beds in this region are sequestering carbon. Early results indicate that cores taken in marsh dominated by C3 plants (Scirpus maritimus) tended to be the most depleted in 13C with δ13C values around -25‰. Cores taken in marsh dominated by C4 plants (Spartina alterniflora, Spartina densiflora), seagrass beds (Ruppia maritima) , and non vegetated areas were generally isotopically heavier with δ13C values ranging -20‰ to -15‰, indicating a mix of organic sources in the sediments. The δ15N values and C/N ratios both varied with most values falling in a range of 2-8‰ and 7-20 respectively. Analysis of the δ 34S isotope composition of the sediments is currently underway and may provide better information on the relative contributions of macro and micro algae in the sediments. The present data will reveal the carbon stock size, as well as the types and history of organic matter deposition in Patos Lagoon estuary.

  12. Drivers of estuarine benthic species distribution patterns following a restoration of a seagrass bed: a functional trait analyses.

    PubMed

    Dolbeth, Marina; Cardoso, Patrícia; Grilo, Tiago; Raffaelli, Dave; Pardal, Miguel Ângelo

    2013-07-15

    We integrate information on functional diversity (FD) patterns from estuarine intertidal benthic communities from different habitats and along a temporal disturbance gradient, to understand the drivers of species coexistence patterns. Species and traits' biomass levels seemed to be first determined by habitat filtering, selecting those traits better adapted to the biologically challenging estuarine environment. Within that subset of traits and within each habitat, biotic interactions were probably high, as evidenced by high α-diversity and community weighted mean differences. The former patterns hold for the disturbance/recovery scenario considered. However, as the estuary recovered, biomass became more distributed among different trait categories, consistent with increases in FD when the seagrass started to increase. Policy towards the restoration of seagrass bed and other biogenic structures, and improving the connectivity within adjacent systems were confirmed and suggested, as this would imply higher FD and potentially higher resilience to disturbance within the estuarine intertidal system.

  13. Determination of in situ biomass and energetics in seagrass beds on the west coast of Florida. Topical report, May 1982-January 1984

    SciTech Connect

    Dawes, C.J.

    1984-01-01

    The Gulf Coastal region of Florida supports extensive grass beds that almost continuously cover the shallow (1-5m) depths from Apalachicola Bay to Anclote Bay and in Tampa Bay. Attached and drift benthic seaweeds occur as well and may have higher energetic yields than the seagrasses. The shallow and continuous beds offer a possible source for plant biomass use in methane production, if sufficient material is available throughout the year and the energetics are high enough. Triweekly samplings at three sites around Tampa Bay and bimonthly samplings at four sites along the west coast of Florida showed highest biomass occurring during the spring through fall months. The available biomass of combined attached and drift seagrasses and seaweeds was lower than that predicted when compared with terrestrial crops. Naturally occurring seagrass and seaweed beds do not have sufficient biomass to justify harvesting for biogass production, although energetics levels are high.

  14. SEDIMENT AND PLANT PHOSPHORUS IN TWO THALASSIA TESTUDINUM SEAGRASS BEDS OF SANTA ROSA SOUND, NW FLORIDA

    EPA Science Inventory

    We investigated phosphorus concentrations in the seagrass, Thalassia testudinum, and the supporting quartz sediments of two meadows in Santa Rosa Sound. One meadow was sampled during 2002, and the other during 2003. Triplicate sediment and biomass cores were obtained from beneath...

  15. The relative importance of mangroves and seagrass beds as feeding habitats for resident and transient fishes from Florida and Belize:: evidence from dietary and stable isotope analyses

    EPA Science Inventory

    In the western Atlantic region, the contribution of mangrove food-sources to fish diets has been considered of more limited importance then previously expected due to their constant flooding and proximity to adjacent coastal habitats such as seagrass beds which provide potential ...

  16. Overgrazing of a large seagrass bed by the sea urchin Lytechinus variegatus in Outer Florida Bay

    USGS Publications Warehouse

    Rose, C.D.; Sharp, W.C.; Kenworthy, W.J.; Hunt, J.H.; Lyons, W.G.; Prager, E.J.; Valentine, J.F.; Hall, M.O.; Whitfield, P.E.; Fourqurean, J.W.

    1999-01-01

    Unusually dense aggregations of the sea urchin Lytechinus variegatus overgrazed at least 0.81 km2 of seagrass habitat in Outer Florida Bay (USA) between August 1997 and May 1998. Initially, sea-urchin densities were as high as 364 sea urchins m-2, but they steadily declined to within a range of 20 to 50 sea urchins m-2 by December 1998. Prior to this event, sea-urchin densities were 95% of the short-shoot apical meristems were removed by sea-urchin grazing in our study area. Such extensive loss may severely limit recovery of this seagrass community by vegetative reproduction. Effects of the removal of seagrass biomass have already resulted in the depletion of epifaunal-infaunal mollusk assemblages and resuspension of fine-grained (<64 ??m) surface sediments - which have caused significant changes in community structure and in the physical properties of the sediments. These changes, coupled with the loss of essential fishery habitat, reductions in primary and secondary production, and degradation of water quality, may lead to additional, longer-term, indirect effects that may extend beyond the boundaries of the grazed areas and into adjacent coastal ecosystems.

  17. Effect of nutrient enrichment on the source and composition of sediment organic carbon in tropical seagrass beds in the South China Sea.

    PubMed

    Liu, Songlin; Jiang, Zhijian; Zhang, Jingping; Wu, Yunchao; Lian, Zhonglian; Huang, Xiaoping

    2016-09-15

    To assess the effect of nutrient enrichment on the source and composition of sediment organic carbon (SOC) beneath Thalassia hemprichii and Enhalus acoroides in tropical seagrass beds, Xincun Bay, South China Sea, intertidal sediment, primary producers, and seawater samples were collected. No significant differences on sediment δ(13)C, SOC, and microbial biomass carbon (MBC) were observed between T. hemprichii and E. acoroides. SOC was mainly of autochthonous origin, while the contribution of seagrass to SOC was less than that of suspended particulate organic matter, macroalgae and epiphytes. High nutrient concentrations contributed substantially to SOC of seagrass, macroalgae, and epiphytes. The SOC, MBC, and MBC/SOC ratio in the nearest transect to fish farming were the highest. This suggested a more labile composition of SOC and shorter turnover times in higher nutrient regions. Therefore, the research indicates that nutrient enrichment could enhance plant-derived contributions to SOC and microbial use efficiency.

  18. Habitat Use by Fishes in Coral Reefs, Seagrass Beds and Mangrove Habitats in the Philippines

    PubMed Central

    Honda, Kentaro; Nakamura, Yohei; Nakaoka, Masahiro; Uy, Wilfredo H.; Fortes, Miguel D.

    2013-01-01

    Understanding the interconnectivity of organisms among different habitats is a key requirement for generating effective management plans in coastal ecosystems, particularly when determining component habitat structures in marine protected areas. To elucidate the patterns of habitat use by fishes among coral, seagrass, and mangrove habitats, and between natural and transplanted mangroves, visual censuses were conducted semiannually at two sites in the Philippines during September and March 2010–2012. In total, 265 species and 15,930 individuals were recorded. Species richness and abundance of fishes were significantly higher in coral reefs (234 species, 12,306 individuals) than in seagrass (38 species, 1,198 individuals) and mangrove (47 species, 2,426 individuals) habitats. Similarity tests revealed a highly significant difference among the three habitats. Fishes exhibited two different strategies for habitat use, inhabiting either a single (85.6% of recorded species) or several habitats (14.4%). Some fish that utilized multiple habitats, such as Lutjanus monostigma and Parupeneus barberinus, showed possible ontogenetic habitat shifts from mangroves and/or seagrass habitats to coral reefs. Moreover, over 20% of commercial fish species used multiple habitats, highlighting the importance of including different habitat types within marine protected areas to achieve efficient and effective resource management. Neither species richness nor abundance of fishes significantly differed between natural and transplanted mangroves. In addition, 14 fish species were recorded in a 20-year-old transplanted mangrove area, and over 90% of these species used multiple habitats, further demonstrating the key role of transplanted mangroves as a reef fish habitat in this region. PMID:23976940

  19. Functional changes due to invasive species: Food web shifts at shallow Posidonia oceanica seagrass beds colonized by the alien macroalga Caulerpa racemosa

    NASA Astrophysics Data System (ADS)

    Deudero, S.; Box, A.; Alós, J.; Arroyo, N. L.; Marbà, N.

    2011-06-01

    species and consequent trophic guild and niche breadth shifts at invaded Caulerpa beds increase our understanding of the seagrass systems.

  20. Dracograllus trukensis sp. nov. (Draconematidae: Nematoda) from a seagrass bed ( Zostera spp.) in Chuuk Islands, Micronesia, Central Western Pacific Ocean

    NASA Astrophysics Data System (ADS)

    Min, Wongi; Kim, Dongsung; Decraemer, Wilfrida; Rho, Hyun Soo

    2016-09-01

    A new species of free-living marine draconematid nematode, Dracograllus trukensis sp. nov., is described based on the specimens collected from the sediments of a intertidal seagrass bed from Chuuk Islands, Micronesia. Dracograllus trukensis sp. nov. differs from other species of the genus by the combination of the following characteristics: the presence of numerous minute spiny ornamented body cuticular annules in both sexes, eight cephalic adhesion tubes inserted on the head capsule in both sexes, the presence of stiff posteriorly directed setae anterior to posterior adhesion tubes in both sexes, the shape (large, elongated, open loop-shaped in male and large, elongated, closed loop-shaped in female) and position (longer ventral arm extending to the first body annule in male) of amphideal fovea, shorter spicule length (34-42 μm), the presence of sexual dimorphism in shape and length of the non-annulated tail terminus, and number of posterior sublateral adhesion tubes (10 in male and 13-15 in female) and posterior subventral adhesion tubes (8-10 in male and 9-11 in female). A comparative table on the biogeographical and ecological characteristics of the species of Dracograllus is presented. This is the first taxonomic report on the genus Dracograllus from Chuuk Islands, Micronesia, central western Pacific Ocean.

  1. Effects of Nutrient Enrichment on Primary Production and Biomass of Sediment Microalgae in a Subtropical Seagrass Bed

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Eutrophication of coastal waters often leads to excessive growth of microalgal epiphytes attached to seagrass leaves; however, the effect of increased nutrient levels on sediment microalgae has not been studied within seagrass communities. A slow-release NPK Osmocote fertilizer was added to sedimen...

  2. The impact of 85 years of coastal development on shallow seagrass beds (Posidonia oceanica L. (Delile)) in South Eastern France: A slow but steady loss without recovery

    NASA Astrophysics Data System (ADS)

    Holon, F.; Boissery, P.; Guilbert, A.; Freschet, E.; Deter, J.

    2015-11-01

    Shallow Posidonia oceanica beds (0 to -15 m), the most common seagrass in the Mediterranean, were mapped from aerial photographs dating from the 1920's and from 2012 along 800 km of coastline in South-Eastern France (Provence-Alpes-Côte-d'Azur region). Changes in P. oceanica bed spatial distribution (limits and extent) during these 85 years were analyzed in terms of concordance (remaining areas), positive discordance (expanding areas) or negative discordance (lost areas). Lost areas were linked with direct or indirect impacts of coastal development (artificialized coastlines (namely harbours, ports of refuge, landfills, artificial beaches, groynes and pontoons, submarine pipelines and aquatic farms) visible on the photographs. The comparison showed that 73% of the shallow limits have declined. Considering spatial extent, remaining seagrass meadows areas accounted for the major part (85%), while lost areas accounted for 13% and expanding areas for 1.1%. Lost areas were mainly linked with artificial coastlines but 44% remained with undetermined causes (invisible pressures and/or mixed effects). The analysis of 96 coastal facilities creating the artificial (namely man-made) coastlines showed that the highest impact over the longest distance (5 km) was caused by harbours. Only artificial beaches had such a distant impact. Pontoons were the least surrounded by lost seagrass meadows areas. These quantitative data offer important information for marine conservation.

  3. Seagrass beds as ocean acidification refuges for mussels? High resolution measurements of pCO2 and O2 in a Zostera marina and Mytilus edulis mosaic habitat

    NASA Astrophysics Data System (ADS)

    Saderne, V.; Fietzek, P.; Aßmann, S.; Körtzinger, A.; Hiebenthal, C.

    2015-07-01

    It has been speculated that macrophytes beds might act as a refuge for calcifiers from ocean acidification. In the shallow nearshores of the western Kiel Bay (Baltic Sea), mussel and seagrass beds are interlacing, forming a mosaic habitat. Naturally, the diverse physiological activities of seagrasses and mussels are affected by seawater carbonate chemistry and they locally modify it in return. Calcification by shellfishes is sensitive to seawater acidity; therefore the photosynthetic activity of seagrasses in confined shallow waters creates favorable chemical conditions to calcification at daytime but turn the habitat less favorable or even corrosive to shells at night. In contrast, mussel respiration releases CO2, turning the environment more favorable for photosynthesis by adjacent seagrasses. At the end of summer, these dynamics are altered by the invasion of high pCO2/low O2 coming from the deep water of the Bay. However, it is in summer that mussel spats settle on the leaves of seagrasses until migrating to the permanent habitat where they will grow adult. These early life phases (larvae/spats) are considered as most sensitive with regard to seawater acidity. So far, the dynamics of CO2 have never been continuously measured during this key period of the year, mostly due to the technological limitations. In this project we used a combination of state-of-the-art technologies and discrete sampling to obtain high-resolution time-series of pCO2 and O2 at the interface between a seagrass and a mussel patch in Kiel Bay in August and September 2013. From these, we derive the entire carbonate chemistry using statistical models. We found the monthly average pCO2 more than 50 % (approx. 640 μatm for August and September) above atmospheric equilibrium right above the mussel patch together with large diel variations of pCO2 within 24 h: 887 ± 331 μatm in August and 742 ± 281 μatm in September (mean ± SD). We observed important daily corrosiveness for calcium

  4. Diversity of assimilatory nitrate reductase genes from plankton and epiphytes associated with a seagrass bed.

    PubMed

    Adhitya, Anita; Thomas, Florence I M; Ward, Bess B

    2007-11-01

    Assimilatory nitrate reductase gene fragments were isolated from epiphytes and plankton associated with seagrass blades collected from Tampa Bay, Florida, USA. Nitrate reductase genes from diatoms (NR) and heterotrophic bacteria (nasA) were amplified by polymerase chain reaction (PCR) using two sets of degenerate primers. A total of 129 NR and 75 nasA clones from four clone libraries, two from each of epiphytic and planktonic components, were sequenced and aligned. In addition, genomic DNA sequences for the NR fragment were obtained from Skeletonema costatum and Thalassiosira weissflogii diatom cultures. Rarefaction analysis with an operational taxonomic unit cut-off of 6% indicated that diversity of the NR and nasA clone libraries were similar, and that sequencing of the clone libraries was not yet saturated. Phylogenetic analysis indicated that 121 of the 129 NR clones sequenced were similar to diatom sequences. Of the eight non-diatom sequences, four were most closely related to the sequence of Chlorella vulgaris. Introns were found in 8% of the Tampa Bay NR sequences; introns were also observed in S. costatum, but not T. weissflogii. Introns from within the same clone library exhibited close similarity in nucleotide sequence, position and length; the corresponding exon sequences were unique. Introns from within the same component were similar in position and length, but not in nucleotide sequence. These findings raise questions about the function of introns, and mechanisms or time evolution of intron formation. A large cluster of 14 of the 75 nasA sequences was similar to sequences from Vibrio species; other sequences were closely related to sequences from Alteromonas, alpha-proteobacteria and Marinomonas-like species. Biogeographically consistent patterns were observed for the nasA Tampa Bay sequences compared with sequences from other locations: for example, Tampa Bay sequences were similar to those from the South Atlantic Bight, but not the Barents Sea. The

  5. Differences Among Fish Assemblages Associated with Nearshore Posidonia oceanica Seagrass Beds, Rocky algal Reefs and Unvegetated Sand Habitats in the Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Guidetti, P.

    2000-04-01

    Fish assemblages associated with nearshore Posidonia oceanica seagrass beds, rocky-algal reefs and unvegetated sandy substrates were studied at two sampling localities, Otranto (Apulian coast) and S. Domino (Tremiti Islands), located in the Southern and Central Adriatic Seas (Mediterranean Sea), respectively. Data were collected in situ by using non-destructive diver visual census methodology. A higher species richness and fish density were observed over the Posidonia seagrass and, in turn, the rocky-algal reef and unvegetated sand habitats. Planktivorous fish species ( Spicara maena, Spicara smaris and Chromis chromis) showing patchy distributions were dominant in terms of abundance at both localities. The two former species did not show any particular habitat preference, while C. chromis was common over both the Posidonia and rocky-algal habitats and was only occasionally recorded over sand. Symphodus ocellatus , Diplodus annularis and Spondyliosoma cantharus were the most common species in the P. oceanica seagrass beds. Symphodus roissali, Symphodus tinca and Diplodus sargus were mainly associated with the rocky-algal reef habitats, while other species, such as Gymnammodytes cicerellus, Lithognathus mormyrus , Gobius geniporus, Mullus barbatus and Uranoscopus scaber, were censused over the unvegetated sand habitats. A cluster analysis performed on the entire fish density data set showed distinct groupings for seagrass, rocky-algal and bare sand fish assemblages, regardless of season and sampling site. Fish assemblages in the more structured (seagrass and rocky-algal reef) habitats were relatively similar to each other but quite different from those of the unstructured bare sands. With regard to small-sized specimens (juvenile stages including recruits), those of S. ocellatus, Symphodus mediterraneus, Serranus cabrilla, D. annularis, S. cantharus and Sarpa salpa were mainly censused over P. oceanica beds, while juveniles of C. chromis inhabited predominantly

  6. Diurnal time-activity budgets of redheads (Aythya americana) wintering in seagrass beds and coastal ponds in Louisiana and Texas

    USGS Publications Warehouse

    Michot, T.C.; Woodin, M.C.; Adair, S.E.; Moser, E.B.

    2006-01-01

    Diurnal time-activity budgets were determined for wintering redheads (Aythya americana) from estuarine seagrass beds in Louisiana (Chandeleur Sound) and Texas (Laguna Madre) and from ponds adjacent to the Laguna Madre. Activities differed (p<0.0001) by location, month, and diurnal time period. Resting and feeding were the most frequent activities of redheads at the two estuarine sites, whereas drinking was almost nonexistent. Birds on ponds in Texas engaged most frequently in resting and drinking, but feeding was very infrequent. Redheads from the Louisiana estuarine site rested less than birds in Texas at either the Laguna Madre or freshwater ponds. Redheads in Louisiana fed more than birds in Texas; this was partially because of weather differences (colder temperatures in Louisiana), but the location effect was still significant even when we adjusted the model for weather effects. Redheads in Louisiana showed increased resting and decreased feeding as winter progressed, but redheads in Texas did not exhibit a seasonal pattern in either resting or feeding. In Louisiana, birds maintained a high level of feeding activity during the early morning throughout the winter, whereas afternoon feeding tapered off in mid- to late-winter. Texas birds showed a shift from morning feeding in early winter to afternoon feeding in late winter. Males and females at both Chandeleur Sound and Laguna Madre showed differences in their activities, but because the absolute difference seldom exceeded 2%, biological significance is questionable. Diurnal time-activity budgets of redheads on the wintering grounds are influenced by water salinities and the use of dietary fresh water, as well as by weather conditions, tides, and perhaps vegetation differences between sites. The opportunity to osmoregulate via dietary freshwater, vs. via nasal salt glands, may have a significant effect on behavioral allocations. ?? Springer 2006.

  7. Assessment of propeller and off-road vehicle scarring in seagrass beds and wind-tidal flats of the southwestern Gulf of Mexico

    USGS Publications Warehouse

    Martin, S.R.; Onuf, C.P.; Dunton, K.H.

    2008-01-01

    We used aerial photography and GIS to establish a quantitative baseline of propeller and off-road vehicle (ORV) scarring in seagrass and wind-tidal flats of the upper Laguna Madre in the Padre Island National Seashore (Texas, USA). We also examined scar recovery through comparison of recent (2002, 2005) and historical (1967) aerial photographs of the study area. Scarring intensity was calculated using two different methods. In the first, polygons were visually drawn around groups of scars on digital images. Scarring intensity was estimated as light (20%), based on the total coverage of scars within each polygon (taking into account the length, width, and density of scars). We developed a more objective method that employed creation of vector grid cells and buffers that incorporated the localized ecological impact of scars. Results of spatial and temporal analysis revealed that the polygon approach greatly underestimated the magnitude of scarring. For example, in a single photograph, 7% of seagrass area was lightly scarred according to the polygon method; but light scarring increased to 51% according to grid analysis of the same image. Our results also indicated that propeller scars in Halodule wrightii beds appear to recover in less than three years and ORV tracks have persisted in the wind-tidal flats for at least 38 years. Our approach provides resource managers with procedures for a more objective and efficient assessment of physical disturbances to seagrass and wind-tidal flats caused by boats and ORVs. ?? 2008 by Walter de Gruyter.

  8. The effect of ocean acidification on carbon storage and sequestration in seagrass beds; a global and UK context.

    PubMed

    Garrard, Samantha L; Beaumont, Nicola J

    2014-09-15

    Ocean acidification will have many negative consequences for marine organisms and ecosystems, leading to a decline in many ecosystem services provided by the marine environment. This study reviews the effect of ocean acidification (OA) on seagrasses, assessing how this may affect their capacity to sequester carbon in the future and providing an economic valuation of these changes. If ocean acidification leads to a significant increase in above- and below-ground biomass, the capacity of seagrass to sequester carbon will be significantly increased. The associated value of this increase in sequestration capacity is approximately £500 and 600 billion globally between 2010 and 2100. A proportionally similar increase in carbon sequestration value was found for the UK. This study highlights one of the few positive stories for ocean acidification and underlines that sustainable management of seagrasses is critical to avoid their continued degradation and loss of carbon sequestration capacity.

  9. Florida seagrass habitat evaluation: A comparative survey for chemical quality

    EPA Science Inventory

    Contaminant concentrations were determined for media associated with 13 Florida seagrass beds. Concentrations of 10 trace metals were more commonly detected in surface water, sediment and two seagrass species than PAHs, pesticides and PCBs. Concentrations of copper and arsenic ...

  10. Benthic community responses to macroalgae invasions in seagrass beds: Diversity, isotopic niche and food web structure at community level

    NASA Astrophysics Data System (ADS)

    Deudero, S.; Box, A.; Vázquez-Luis, M.; Arroyo, N. L.

    2014-04-01

    Trophic paths between species are a useful tool for analysing the impact of species invasions of a biotic community. Species invasions produce changes at trophic level and diversity shifts by replacing native species with species of similar ecological niche. This study focused on the effects of macroalgal invasions on seagrass ecosystems. We conducted two - year bimonthly sampling of a pristine Posidonia oceanica seagrass meadow and dead matte colonized by three Caulerpa species bimonthly. The largest changes in faunal composition were found in meadows colonized by Caulerpa prolifera, where major differences in infaunal taxonomic distinctness were apparent. On the other hand, the infaunal community was quite similar between the two invasive Caulerpa species (Caulerpa taxifolia and Caulerpa racemosa). The isotopic niche based on the main trophic guilds established using stable isotope signatures at community level resulted in a highly compacted and 15N-enriched C. prolifera food web structure, indicating high overlap of food source utilization among faunal components, which is typical of degraded systems. Conversely, the P. oceanica ecosystem presented the most complex food web, while the influence of the 2 invasive species were similar. An attempt to reconstruct the food web at each vegetated habitat revealed high trophic linkages among the different trophic levels with a continuous transition among them by the various trophic guilds suggesting an adaptation response of the different organisms to the new habitat forming species.

  11. Use of a seagrass residency index to apportion commercial fishery landing values and recreation fisheries expenditure to seagrass habitat service.

    PubMed

    Jackson, Emma L; Rees, Siân E; Wilding, Catherine; Attrill, Martin J

    2015-06-01

    Where they dominate coastlines, seagrass beds are thought to have a fundamental role in maintaining populations of exploited species. Thus, Mediterranean seagrass beds are afforded protection, yet no attempt to determine the contribution of these areas to both commercial fisheries landings and recreational fisheries expenditure has been made. There is evidence that seagrass extent continues to decline, but there is little understanding of the potential impacts of this decline. We used a seagrass residency index, that was trait and evidence based, to estimate the proportion of Mediterranean commercial fishery landings values and recreation fisheries total expenditure that can be attributed to seagrass during different life stages. The index was calculated as a weighted sum of the averages of the estimated residence time in seagrass (compared with other habitats) at each life stage of the fishery species found in seagrass. Seagrass-associated species were estimated to contribute 30%-40% to the value of commercial fisheries landings and approximately 29% to recreational fisheries expenditure. These species predominantly rely on seagrass to survive juvenile stages. Seagrass beds had an estimated direct annual contribution during residency of €58-91 million (4% of commercial landing values) and €112 million (6% of recreation expenditure) to commercial and recreational fisheries, respectively, despite covering <2% of the area. These results suggest there is a clear cost of seagrass degradation associated with ineffective management of seagrass beds and that policy to manage both fisheries and seagrass beds should take into account the socioeconomic implications of seagrass loss to recreational and commercial fisheries.

  12. AUTOMATED PRODUCTION OF SEAGRASS MAPS FROM SIDESCAN SONAR IMAGERY: ACCURACY, VARIABILITY AND PATCH RESOLUTION

    EPA Science Inventory

    Maps of seagrass beds are useful for monitoring estuarine condition, managing habitats, and modeling estuarine processes. We recently developed inexpensive methods for collecting and classifying sidescan sonar (SSS) imagery for seagrass presence in turbid waters as shallow as 1-...

  13. Abstracts

    ERIC Educational Resources Information Center

    American Biology Teacher, 1977

    1977-01-01

    Included are over 50 abstracts of papers being presented at the 1977 National Association of Biology Teachers Convention. Included in each abstract are the title, author, and summary of the paper. Topics include photographic techniques environmental studies, and biological instruction. (MA)

  14. Seagrass ecosystems in the Western Indian Ocean.

    PubMed

    Gullström, Martin; de la Torre Castro, Maricela; Bandeira, Salomão; Björk, Mats; Dahlberg, Mattis; Kautsky, Nils; Rönnbäck, Patrik; Ohman, Marcus C

    2002-12-01

    Seagrasses are marine angiosperms widely distributed in both tropical and temperate coastal waters creating one of the most productive aquatic ecosystems on earth. In the Western Indian Ocean (WIO) region, with its 13 reported seagrass species, these ecosystems cover wide areas of near-shore soft bottoms through the 12 000 km coastline. Seagrass beds are found intertidally as well as subtidally, sometimes down to about 40 m, and do often occur in close connection to coral reefs and mangroves. Due to the high primary production and a complex habitat structure, seagrass beds support a variety of benthic, demersal and pelagic organisms. Many fish and shellfish species, including those of commercial interest, are attracted to seagrass habitats for foraging and shelter, especially during their juvenile life stages. Examples of abundant and widespread fish species associated to seagrass beds in the WIO belong to the families Apogonidae, Blenniidae, Centriscidae, Gerreidae, Gobiidae, Labridae, Lethrinidae Lutjanidae, Monacanthidae, Scaridae, Scorpaenidae, Siganidae, Syngnathidae and Teraponidae. Consequently, seagrass ecosystems in the WIO are valuable resources for fisheries at both local and regional scales. Still, seagrass research in the WIO is scarce compared to other regions and it is mainly focusing on botanic diversity and ecology. This article reviews the research status of seagrass beds in the WIO with particular emphasis on fish and fisheries. Most research on this topic has been conducted along the East African coast, i.e. in Kenya, Tanzania, Mozambique and eastern South Africa, while less research was carried out in Somalia and the Island States of the WIO (Seychelles, Comoros, Reunion (France), Mauritius and Madagascar). Published papers on seagrass fish ecology in the region are few and mainly descriptive. Hence, there is a need of more scientific knowledge in the form of describing patterns and processes through both field and experimental work

  15. Coastal resource degradation in the tropics: does the tragedy of the commons apply for coral reefs, mangrove forests and seagrass beds.

    PubMed

    Wilkinson, Clive; Salvat, Bernard

    2012-06-01

    The keynote paper by Garrett Hardin 44 years ago introduced the term 'tragedy of the commons' into our language (Hardin, 1968); this term is now used widely, but it is neither universally accepted nor fully understood. Irrespective, the 'tragedy of the commons' is an increasing reality for more than 500 million people that rely on the biodiversity resources and services of tropical coral reefs, mangrove forests, seagrass beds and associated fisheries. These natural resources continue to decline despite major advances in our scientific understanding of how ecosystems and human populations interact, and the application of considerable conservation and management efforts at scales from local user communities to oceans. Greater effort will be required to avert increasing damage from over-exploitation, pollution and global climate change; all deriving from increasing exploitation driven by poverty and progress i.e. continuing to expand development indefinitely and extraction of resources at industrial scales. However, the 'tragedy' concept has been widely criticized as a simple metaphor for a much larger set of problems and solutions. We argue that the 'tragedy' is essentially real and will continue to threaten the lives of millions of people unless there are some major moral and policy shifts to reverse increasing damage to coastal habitats and resources. We agree with the conclusion by Hardin that the solution to the tragedy will not be through the application of natural sciences, but via implementing exceedingly difficult and controversial moral decisions. An extreme example of a moral and controversial direction suggested by Hardin was in re-examining the 'freedom to breed' as an inherent human value. The need for 'moral decisions' is even greater in 2012.

  16. SULFATE-REDUCING BACTERIA IN THE SEAGRASS RHIZOSPHERE

    EPA Science Inventory

    Seagrasses are rooted in anoxic sediments that support high levels of microbial activity including utilization of sulfate as a terminal electron acceptor which is reduced to sulfide. Sulfate reduction in seagrass bed sediments is stimulated by input of organic carbon through the ...

  17. Changes in Seagrass Species Composition in Northwestern Gulf of Mexico Estuaries: Effects on Associated Seagrass Fauna

    PubMed Central

    Ray, Brandon R.; Johnson, Matthew W.; Cammarata, Kirk; Smee, Delbert L.

    2014-01-01

    The objective of this study was to measure the communities associated with different seagrass species to predict how shifts in seagrass species composition may affect associated fauna. In the northwestern Gulf of Mexico, coverage of the historically dominant shoal grass (Halodule wrightii) is decreasing, while coverage of manatee grass (Syringodium filiforme) and turtle grass (Thalassia testudinum) is increasing. We conducted a survey of fishes, crabs, and shrimp in monospecific beds of shoal, manatee, and turtle grass habitats of South Texas, USA to assess how changes in sea grass species composition would affect associated fauna. We measured seagrass parameters including shoot density, above ground biomass, epiphyte type, and epiphyte abundance to investigate relationships between faunal abundance and these seagrass parameters. We observed significant differences in communities among three seagrass species, even though these organisms are highly motile and could easily travel among the different seagrasses. Results showed species specific relationships among several different characteristics of the seagrass community and individual species abundance. More work is needed to discern the drivers of the complex relationships between individual seagrass species and their associated fauna. PMID:25229897

  18. Changes in seagrass species composition in northwestern Gulf of Mexico estuaries: effects on associated seagrass fauna.

    PubMed

    Ray, Brandon R; Johnson, Matthew W; Cammarata, Kirk; Smee, Delbert L

    2014-01-01

    The objective of this study was to measure the communities associated with different seagrass species to predict how shifts in seagrass species composition may affect associated fauna. In the northwestern Gulf of Mexico, coverage of the historically dominant shoal grass (Halodule wrightii) is decreasing, while coverage of manatee grass (Syringodium filiforme) and turtle grass (Thalassia testudinum) is increasing. We conducted a survey of fishes, crabs, and shrimp in monospecific beds of shoal, manatee, and turtle grass habitats of South Texas, USA to assess how changes in sea grass species composition would affect associated fauna. We measured seagrass parameters including shoot density, above ground biomass, epiphyte type, and epiphyte abundance to investigate relationships between faunal abundance and these seagrass parameters. We observed significant differences in communities among three seagrass species, even though these organisms are highly motile and could easily travel among the different seagrasses. Results showed species specific relationships among several different characteristics of the seagrass community and individual species abundance. More work is needed to discern the drivers of the complex relationships between individual seagrass species and their associated fauna.

  19. Lugworm ( Abarenicola affinis) in seagrass and unvegetated habitats

    NASA Astrophysics Data System (ADS)

    Goerlitz, Stefan; Berkenbusch, Katrin; Probert, P. Keith

    2015-06-01

    In Otago, southern New Zealand, the lugworm Abarenicola affinis resides in neighbouring tidal inlets with and without seagrass ( Zostera muelleri). A comparison of abundance, body size and biomass of A. affinis between seagrass habitat (Papanui Inlet) and unvegetated habitat (Hoopers Inlet) showed little seasonal variation of these parameters in each habitat and relatively similar abundances between both habitats. In contrast, lugworm biomass was considerably lower in the seagrass habitat due to the lack of large individuals compared with unvegetated habitat. In the seagrass habitat, there was a significant negative influence of Z. muelleri below-ground biomass on abundance and biomass of A. affinis, indicating that seagrass affected lugworm burrowing and/or feeding processes. In contrast to the unvegetated habitat, where lugworms spread relatively evenly across the intertidal area, lugworms were mostly restricted to the upper intertidal zone in the seagrass habitat. The findings suggest that the extensive seagrass bed in the mid and low intertidal zones of Papanui Inlet limited lugworm distribution in an otherwise suitable habitat. Whereas small lugworms colonised seagrass areas, the largest individuals occurred only in unvegetated sediment and seemed to be more hampered by the presence of seagrass than smaller individuals. The findings highlight negative feedback between antagonistic ecosystem engineers, with the potential of seagrass physical structures (autogenic engineering) to impact negatively on lugworm activity (allogenic engineering).

  20. Trophic cascades on the edge: fostering seagrass resilience via a novel pathway.

    PubMed

    Hughes, Brent B; Hammerstrom, Kamille K; Grant, Nora E; Hoshijima, Umi; Eby, Ron; Wasson, Kerstin

    2016-09-01

    Despite widespread degradation, some coastal ecosystems display remarkable resilience. For seagrasses, a century-old paradigm has implicated macroalgal blooms stimulated by anthropogenic nutrient, loading as a primary driver of seagrass decline, yet relatively little attention has been given to drivers of seagrass resilience. In Elkhorn Slough, CA, an estuarine system characterized by extreme anthropogenic nutrient loading and macroalgal (Ulva spp.) blooms, seagrass (Zostera marina) beds have recovered concurrent with colonization of the estuary by top predators, sea otters (Enhydra lutris). Here, we follow up on the results of a previous experiment at the seagrass interior, showing how sea otters can generate a trophic cascade that promotes seagrass. We conducted an experiment and constructed structural equation models to determine how sea otters, through a trophic cascade, might affect the edge of seagrass beds where expansion occurs. We found that at the edge, sea otters promoted both seagrass and ephemeral macroalgae, with the latter contributing beneficial grazers to the seagrass. The surprising results that sea otters promote two potentially competing vegetation types, and a grazer assemblage at their boundary provides a mechanism by which seagrasses can expand in eutrophic environments, and contributes to a growing body of literature demonstrating that ephemeral macroalgae are not always negatively associated with seagrass. Our results highlight the potential for top predator recovery to enhance ecosystem resilience to anthropogenic alterations through several cascading mechanisms.

  1. Integrating scales of seagrass monitoring to meet conservation needs

    USGS Publications Warehouse

    Neckles, Hilary A.; Kopp, Blaine S.; Peterson, Bradley J.; Pooler, Penelope S.

    2012-01-01

    We evaluated a hierarchical framework for seagrass monitoring in two estuaries in the northeastern USA: Little Pleasant Bay, Massachusetts, and Great South Bay/Moriches Bay, New York. This approach includes three tiers of monitoring that are integrated across spatial scales and sampling intensities. We identified monitoring attributes for determining attainment of conservation objectives to protect seagrass ecosystems from estuarine nutrient enrichment. Existing mapping programs provided large-scale information on seagrass distribution and bed sizes (tier 1 monitoring). We supplemented this with bay-wide, quadrat-based assessments of seagrass percent cover and canopy height at permanent sampling stations following a spatially distributed random design (tier 2 monitoring). Resampling simulations showed that four observations per station were sufficient to minimize bias in estimating mean percent cover on a bay-wide scale, and sample sizes of 55 stations in a 624-ha system and 198 stations in a 9,220-ha system were sufficient to detect absolute temporal increases in seagrass abundance from 25% to 49% cover and from 4% to 12% cover, respectively. We made high-resolution measurements of seagrass condition (percent cover, canopy height, total and reproductive shoot density, biomass, and seagrass depth limit) at a representative index site in each system (tier 3 monitoring). Tier 3 data helped explain system-wide changes. Our results suggest tiered monitoring as an efficient and feasible way to detect and predict changes in seagrass systems relative to multi-scale conservation objectives.

  2. Seagrass distribution and abundance in Eastern Gulf of Mexico coastal waters

    NASA Astrophysics Data System (ADS)

    Iverson, Richard L.; Bittaker, Henry F.

    1986-05-01

    The marine angiosperms Thalassia testudinum, Syringodium filiforme, and Halodule wrightii form two of the largest reported seagrass beds along the northwest and southern coasts of Florida where they cover about 3000 square km in the Big Bend area and about 5500 square km in Florida Bay, respectively. Most of the leaf biomass in the Big Bend area and outer Florida Bay was composed of Thalassia testudinum and Syringodium filiforme which were distributed throughout the beds but which were more abundant in shallow depths. A short-leaved form of Halodule wrightii grew in monotypic stands in shallow water near the inner edges of the beds, while Halophila decipiens and a longer-leaved variety of H. wrightii grew scattered throughout the beds, in monotypic stands near the outer edges of the beds, and in deeper water outside the beds. Halophila engelmanni was observed scattered at various depths throughout the seagrass beds and in monospecific patches in deep water outside the northern bed. Ruppia maritima grew primarily in brackish water around river mouths. The cross-shelf limits of the two major seagrass beds are controlled nearshore by increased water turbidity and lower salinity around river mouths and off-shore by light penetration to depths which receive 10% or more of sea surface photosynthetically active radiation. Seagrasses form large beds only along low energy reaches of the coast. The Florida Bay seagrass bed contained about twice the short-shoot density of both Thalassia testudinum and Syringodium filiforme, for data averaged over all depths, and about four times the average short-shoot density of both species in shallow water compared with the Big Bend seagrass bed. The differences in average seagrass abundance between Florida Bay and the Big Bend area may be a consequence of the effects of greater seasonal solar radiation and water temperature fluctuations experienced by plants in the northern bed, which lies at the northern distribution limit for American

  3. The contribution of scarid herbivory to seagrass ecosystem dynamics in the Indo-Pacific

    NASA Astrophysics Data System (ADS)

    Unsworth, Richard K. F.; Taylor, Joe D.; Powell, Abigail; Bell, James J.; Smith, David J.

    2007-08-01

    The functional importance of herbivory is well established within terrestrial ecosystems yet within marine ecosystems, specifically seagrass beds, consumption by herbivores has generally been considered to be of little importance due to its minor contribution to turnover of growth. The present paper challenges this assumption within the Indo-Pacific and shows that scarid (parrotfish) herbivory may have a functionally important role in the export of seagrass detrital material. Estimation of scarid herbivory on dominant Indo-Pacific seagrass species was conducted using a three pronged approach. We estimated: background levels of scarid seagrass bites; in-situ rates of grazing using tethering experiments; and seagrass grazing effect per individual scarid, which was scaled up to estimate the grazing effects of the local scarid population. All research was carried out within the Wakatobi Marine National Park, Indonesia. Research found scarid herbivory to be an important process within an Indo-Pacific seagrass bed causing the loss of up to ten times (average, four times) the daily seagrass growth. T. hemprichii was found to be lost at a rate of 0.28 ± 0.08 g DW day -1, while E. acoroides was lost at a rate of 2.85 ± 0.43 g DW day -1. We propose that such high rates of seagrass consumption are the combined effects of seasonally high grazing rates by resident scarids and short-term effects from shoals of juvenile reef scarids. Scarid grazing was indiscriminate between seagrass species and grazing was dependant on seagrass availability rather than nutritional quality. In conclusion, the present research finds scarids to be major herbivores within an Indo-Pacific seagrass bed; they not only take up carbon into the food chain through direct seagrass consumption, but also make an important indirect contribution to the detrital food chain through the export of discarded decaying seagrass material.

  4. The ecology of the seagrass meadows of the west coast of Florida: A community profile

    SciTech Connect

    Zieman, J.C.; Zieman, R.T. . Dept. of Environmental Sciences)

    1989-09-01

    This report summarizes information on the ecology of seagrass meadows on the west coast of Florida, from south of Tampa Bay to Pensacola. This area contains more than 3500 ha of seagrass beds, dominated by three species, Thalasia testudinum (turtle grass), Syringodium filiforme (manatee grass), and Halodule wrightii (shoal grass). Beds occur both on the shallow, zero-energy Continental Shelf and in inshore bays and estuaries. Species ecology, distribution, biomass, and productivity of these dominant seagrass species are discussed. Seagrass beds support a very diverse and abundant algal flora and fauna, and these organisms, and seagrass detritus form the base of a productive food chain. Seagrass beds are important nursery areas providing both cover and food, for a number of commercial and sports fishery species. Along the west Florida coast, estuarine grass beds are noticeably more stressed and impacted by human activities than the more pristine nearshore beds. Urban development and dredging and filling are the major threates to seagrass beds in this region. 500 refs., 28 figs., 14 tabs.

  5. SEAGRASS RHIZOSPHERE MICROBIAL COMMUNITIES

    EPA Science Inventory

    Devereux, Richard. 2005. Seagrass Rhizosphere Microbial Communities. In: Interactions Between Macro- and Microorganisms in Marine Sediments. E. Kristense, J.E. Kostka and R.H. Haese, Editors. American Geophysical Union, Washington, DC. p199-216. (ERL,GB 1213).

    Seagrasses ...

  6. SEAGRASS STRESS RESPONSE MODEL: THE IMPORTANCE OF LIGHT, TEMPERATURE, SEDIMENTATION AND GEOCHEMISTRY

    EPA Science Inventory

    Our objective is to define interactions between seagrass and water-column and sediment stressors. The model was developed and optimized for sediments in Thalassia testudinum seagrass beds of Lower Laguna Madre, Texas, USA and is composed of a plant sub-model and a sediment diagen...

  7. EFFECTS OF GREEN MACROALGAE ON CLASSIFICATION OF SEAGRASS IN SIDE SCAN SONAR IMAGERY

    EPA Science Inventory

    High resolution maps of seagrass beds are useful for monitoring estuarine condition, managing fish habitats, and modeling estuarine processes. Side scan sonar (SSS) is one method for producing spatially accurate seagrass maps, although it has not been used widely. Our team rece...

  8. Relative foraminiferan abundance as an indicator of seagrass sediment health:

    NASA Astrophysics Data System (ADS)

    Cajandig, P.; Quiros, A.; Nolan, H.; Tallman, R.; Cooper, N.; Ayala, J.; Courtier, C.

    2013-12-01

    Authors: Patrick Cajandig*, Jose Ayala**, Nathaniel Cooper**, Catherine Courtier**, Hannah Nolan**, Rachelle Tallman**, T.E. Angela L. Quiros** * Davis High-School CA, **University of California Santa Cruz, Ecology and Evolutionary Biology Department Seagrasses are a key component in coastal ecosystems. Found in shallow marine environments, they make a large contribution to coastal ecosystem health by sustaining water quality, stabilizing the sea bottom, and providing habitat as well as food for other organisms. Seagrasses accumulate tiny grains of sediment, increasing water clarity. Just like barren hills are prone to erosion compared to vegetated, rooted down hills, we find a similar situation in the ocean. Seagrasses have broad roots that extend vertically and horizontally to help stabilize the seabed. Seagrasses support a whole ecosystem, because some organisms feed off of the seagrass alone, while others feed off the inhabitants of the seagrass. The quality of sediment is a vital part of seagrass health, just like nutrient rich soils are important to land plants. But what in seagrass sediment is a good indication of health? We hypothesize that seagrass health measures such as percent cover and seagrass species diversity are related to the abundance of foraminiferans relative to other seagrass sediment components. My mentor, T. E. Angela L. Quiros, from the University of California, Santa Cruz (UCSC), collected the sediment samples from seagrass beds in the Philippines. Samples were dried and brought to UCSC for sediment sieving. We used different sized sieves to sort the sediment. These sieves ranged from coarse to very fine sieves (Phi -2.0 (coarse) through +3.0 (fine) going in 0.5 intervals on a log scale). We weighed the sediment that was caught in each tray and separated them into bags of different size classes. To analyze each sample, we subsampled four size classes (Phi's -2.0, -1.5,-1.0, 0.0), and used a dissecting scope to identify and then weigh the

  9. Accumulation of Pb and Cu heavy metals in sea water, sediment, and leaf and root tissue of Enhalus sp. in the seagrass bed of Banten Bay

    NASA Astrophysics Data System (ADS)

    Fauziah, Faiza; Choesin, Devi N.

    2014-03-01

    Banten Bay in Indonesia is a coastal area which has been highly affected by human activity. Previous studies have reported the presence of lead (Pb) and copper (Cu) heavy metals in the seawater of this area. This study was conducted to measure the accumulation of Pb and Cu in seawater, sediment, leaf tissue, and root tissue of the seagrass species Enhalus sp. Sampling was conducted at two observation stations in Banten Bay: Station 1 (St.1) was located closer to the coastline and to industrial plants as source of pollution, while Station 2 (St.2) was located farther away offshore. At each station, three sampling points were established by random sampling. Field sampling was conducted at two different dates, i.e., on 29 May 2012 and 30 June 2012. Samples were processed by wet ashing using concentrated HNO3 acid and measured using Atomic Absorption Spectrometry (AAS). Accumulation of Pb was only detected in sediment samples in St.1, while Cu was detected in all samples. Average concentrations of Cu in May were as follows: sediment St.1 = 0.731 ppm, sediment St.2 = 0.383 ppm, seawater St.1 = 0.163 ppm, seawater St.2 = 0.174 ppm, leaf St.1 = 0.102 ppm, leaf St.2 = 0.132 ppm, root St.1= 0.139 ppm, and root St.2 = 0.075 ppm. Average measurements of Cu in June were: sediment St.1 = 0.260 ppm, leaf St.1 = 0.335 ppm, leaf St.2 = 0.301 ppm, root St.1= 0.047 ppm, and root St.2 = 0.060 ppm. In June, Cu was undetected in St.2 sediment and seawater at both stations. In May, Cu concentration in seawater exceeded the maximum allowable threshold for water as determined by the Ministry of the Environment. Spatial and temporal variation in Pb and Cu accumulation were most probably affected by distance from source and physical conditions of the environment (e.g., water current and mixing).

  10. Accumulation of Pb and Cu heavy metals in sea water, sediment, and leaf and root tissue of Enhalus sp. in the seagrass bed of Banten Bay

    SciTech Connect

    Fauziah, Faiza Choesin, Devi N.

    2014-03-24

    Banten Bay in Indonesia is a coastal area which has been highly affected by human activity. Previous studies have reported the presence of lead (Pb) and copper (Cu) heavy metals in the seawater of this area. This study was conducted to measure the accumulation of Pb and Cu in seawater, sediment, leaf tissue, and root tissue of the seagrass species Enhalus sp. Sampling was conducted at two observation stations in Banten Bay: Station 1 (St.1) was located closer to the coastline and to industrial plants as source of pollution, while Station 2 (St.2) was located farther away offshore. At each station, three sampling points were established by random sampling. Field sampling was conducted at two different dates, i.e., on 29 May 2012 and 30 June 2012. Samples were processed by wet ashing using concentrated HNO{sub 3} acid and measured using Atomic Absorption Spectrometry (AAS). Accumulation of Pb was only detected in sediment samples in St.1, while Cu was detected in all samples. Average concentrations of Cu in May were as follows: sediment St.1 = 0.731 ppm, sediment St.2 = 0.383 ppm, seawater St.1 = 0.163 ppm, seawater St.2 = 0.174 ppm, leaf St.1 = 0.102 ppm, leaf St.2 = 0.132 ppm, root St.1= 0.139 ppm, and root St.2 = 0.075 ppm. Average measurements of Cu in June were: sediment St.1 = 0.260 ppm, leaf St.1 = 0.335 ppm, leaf St.2 = 0.301 ppm, root St.1= 0.047 ppm, and root St.2 = 0.060 ppm. In June, Cu was undetected in St.2 sediment and seawater at both stations. In May, Cu concentration in seawater exceeded the maximum allowable threshold for water as determined by the Ministry of the Environment. Spatial and temporal variation in Pb and Cu accumulation were most probably affected by distance from source and physical conditions of the environment (e.g., water current and mixing)

  11. Predictive Seagrass Habitat Model

    EPA Science Inventory

    Restoration of ecosystem services provided by seagrass habitats in estuaries requires a firm understanding of the modes of action of multiple interacting stressors including nutrients, climate change, coastal land-use change, and habitat modification. We explored the application...

  12. Geoengineering with seagrasses: is credit due where credit is given?

    NASA Astrophysics Data System (ADS)

    Johannessen, Sophia C.; Macdonald, Robie W.

    2016-11-01

    Blue carbon, the carbon fixed by vegetated coastal ecosystems including seagrasses, is reported to have a large potential to sequester atmospheric carbon dioxide. Planting, expanding or protecting seagrass meadows has, accordingly, been proposed as a form of geoengineering. Seagrasses are reported to account for up to 18% of the carbon burial in the world’s oceans, which is on the same order of magnitude as other proposed geoengineering techniques, including iron fertilization. International protocols have been developed to quantify carbon sequestration in seagrass meadows, with a view to awarding carbon credits under the Verified Carbon Standard. Unfortunately, because these protocols do not adequately account for post-depositional processes in marine sediment, they significantly overestimate carbon capture by seagrass beds and give an incorrect view of its distribution. Specifically, neglecting biomixing and remineralization of carbon in surface sediments biases burial rates high, while using sediment carbon inventory (soil carbon stock) over the top 1 m as a proxy for burial rate incorrectly identifies areas of high carbon burial. Seagrass beds likely provide a limited setting for geoengineering, because they generally comprise slowly-accumulating, fine to medium sand, which captures organic carbon less efficiently than fine-grained sediments or rapidly-accumulating delta deposits. While there is no question that seagrass meadows provide valuable habitat, nor that they are disappearing rapidly, their contribution to the global burial of carbon has not yet been established. The danger of geoengineering with seagrasses before reliable assessment methods have been established is that overestimated carbon offsets could lead to a net increase in emissions of carbon dioxide to the atmosphere.

  13. Eutrophication threatens Caribbean seagrasses - An example from Curaçao and Bonaire.

    PubMed

    Govers, Laura L; Lamers, Leon P M; Bouma, Tjeerd J; de Brouwer, Jan H F; van Katwijk, Marieke M

    2014-12-15

    Seagrass beds are globally declining due to human activities in coastal areas. We here aimed to identify threats from eutrophication to the valuable seagrass beds of Curaçao and Bonaire in the Caribbean, which function as nursery habitats for commercial fish species. We documented surface- and porewater nutrient concentrations, and seagrass nutrient concentrations in 6 bays varying in nutrient loads. Water measurements only provided a momentary snapshot, due to timing, tidal stage, etc., but Thalassia testudinum nutrient concentrations indicated long-term nutrient loads. Nutrient levels in most bays did not raise any concern, but high leaf % P values of Thalassia in Piscadera Bay (∼0.31%) and Spanish Water Bay (∼0.21%) showed that seagrasses may be threatened by eutrophication, due to emergency overflow of waste water and coastal housing. We thus showed that seagrasses may be threatened and measures should be taken to prevent loss of these important nursery areas due to eutrophication.

  14. The potential impact of bedform migration on seagrass communities in Torres Strait, northern Australia

    NASA Astrophysics Data System (ADS)

    Daniell, James J.; Harris, Peter T.; Hughes, Michael G.; Hemer, Mark; Heap, Andrew

    2008-09-01

    Seagrass communities in the northwest of Torres Strait are known to disappear episodically over broad areas. Sediment mobility surveys were undertaken within two study areas during the monsoon and trade wind seasons, in the vicinity of Turnagain Island, to find out if the migration of bedforms could explain this disappearance. The two study areas covered sand bank and sand dune environments to compare and contrast their migration characteristics. Repeat multibeam sonar surveys were used to measure dune-crest migration during each season. Our results show that seagrass beds occur in the troughs of sediment-starved dunes, but no seagrass occurs in association with full-bedded dunes that are superimposed on large sand bank features. The coincidence of seagrass beds with the sediment-starved dunes is in spite of the fact that they migrate faster (0.59 m day -1) than full-bedded dunes (0.13 m day -1), which indicates that some other factor (other than dune migration rate) limits seagrass growth within Torres Strait. We suggest that seagrasses are unable to colonise full-bedded dunes because of the semi-continuously transported sand that characterises this environment. In contrast, the troughs of sediment-starved dunes experience only limited bedload transport and are less hostile for seagrasses. A conceptual model is presented to explain the occurrence of seagrass beds in relation to their proximity to migrating sand dunes. Based on our analysis, we conclude that the widespread dieback of seagrasses documented for the Turnagain Island region was not caused by dune migration.

  15. Effects of surrounding land use and water depth on seagrass dynamics relative to a catastrophic algal bloom.

    PubMed

    Breininger, David R; Breininger, Robert D; Hall, Carlton R

    2017-02-01

    Seagrasses are the foundation of many coastal ecosystems and are in global decline because of anthropogenic impacts. For the Indian River Lagoon (Florida, U.S.A.), we developed competing multistate statistical models to quantify how environmental factors (surrounding land use, water depth, and time [year]) influenced the variability of seagrass state dynamics from 2003 to 2014 while accounting for time-specific detection probabilities that quantified our ability to determine seagrass state at particular locations and times. We classified seagrass states (presence or absence) at 764 points with geographic information system maps for years when seagrass maps were available and with aerial photographs when seagrass maps were not available. We used 4 categories (all conservation, mostly conservation, mostly urban, urban) to describe surrounding land use within sections of lagoonal waters, usually demarcated by land features that constricted these waters. The best models predicted that surrounding land use, depth, and year would affect transition and detection probabilities. Sections of the lagoon bordered by urban areas had the least stable seagrass beds and lowest detection probabilities, especially after a catastrophic seagrass die-off linked to an algal bloom. Sections of the lagoon bordered by conservation lands had the most stable seagrass beds, which supports watershed conservation efforts. Our results show that a multistate approach can empirically estimate state-transition probabilities as functions of environmental factors while accounting for state-dependent differences in seagrass detection probabilities as part of the overall statistical inference procedure.

  16. Impacts of docks on seagrass and effects of management practices to ameliorate these impacts

    NASA Astrophysics Data System (ADS)

    Gladstone, William; Courtenay, Glenn

    2014-01-01

    Seagrasses have high conservation and human-use values, but around the world they are being damaged by human activities. Compared to the larger spatial scale at which some human activities affect estuaries and their seagrasses (e.g. catchment disturbance, dredging, pollution, trawling), recreational boating and infrastructure of moorings and docks act at smaller scales. However, the cumulative effects contribute to stresses acting on seagrass beds. This study assessed the effects of docks on the native seagrass Zostera muelleri subsp. capricorni in an estuary in south-east Australia and of current management practices designed to reduce dock impacts on this seagrass. A field survey found that seagrass biomass was significantly reduced below docks, and the effects were not influenced by dock orientation. Management practices requiring the use of a mesh decking to provide greater light penetration reduced, but did not eliminate, the reduction in seagrass biomass caused by docks. A modified beyond BACI experiment provided evidence for a causal link between the installation of wooden or mesh docks and reductions in biomass of seagrass. The reduction in biomass was apparent 6 mo after dock installation, and by 26 mo seagrass biomass had declined by at least 90%. Faced with increasing coastal populations, increases in recreational use, and continued pressures from other human activities, alternative management practices that further minimize the effects of docks are needed.

  17. A DIAGENETIC MODEL FOR SEDIMENT-SEAGRASS INTERACTIONS

    EPA Science Inventory

    The objective of this modeling effort was to better understand the dynamic relationship between seagrass beds and their sedimentary environment using a diagenetic model. The model was developed and optimized for sediments in the Laguna Madre, TX, which is one of the world's larg...

  18. DISTRIBUTION AND QUALITY OF SEAGRASS MEADOWS IN THE PENSACOLA BAY SYSTEM

    EPA Science Inventory

    Abstract for oral presentation: Seagrass meadows have 22 ecological benefits and have an estimated value of $20,500 per acre in Florida. Seagrass meadows support a variety of marine life that includes macroalgae (148 species), epiphytes (1 13 species), macroinvertebrates (230 spe...

  19. Photosynthetic response to globally increasing CO2 of co-occurring temperate seagrass species.

    PubMed

    Borum, Jens; Pedersen, Ole; Kotula, Lukasz; Fraser, Matthew W; Statton, John; Colmer, Timothy D; Kendrick, Gary A

    2016-06-01

    Photosynthesis of most seagrass species seems to be limited by present concentrations of dissolved inorganic carbon (DIC). Therefore, the ongoing increase in atmospheric CO2 could enhance seagrass photosynthesis and internal O2 supply, and potentially change species competition through differential responses to increasing CO2 availability among species. We used short-term photosynthetic responses of nine seagrass species from the south-west of Australia to test species-specific responses to enhanced CO2 and changes in HCO3 (-) . Net photosynthesis of all species except Zostera polychlamys were limited at pre-industrial compared to saturating CO2 levels at light saturation, suggesting that enhanced CO2 availability will enhance seagrass performance. Seven out of the nine species were efficient HCO3 (-) users through acidification of diffusive boundary layers, production of extracellular carbonic anhydrase, or uptake and internal conversion of HCO3 (-) . Species responded differently to near saturating CO2 implying that increasing atmospheric CO2 may change competition among seagrass species if co-occurring in mixed beds. Increasing CO2 availability also enhanced internal aeration in the one species assessed. We expect that future increases in atmospheric CO2 will have the strongest impact on seagrass recruits and sparsely vegetated beds, because densely vegetated seagrass beds are most often limited by light and not by inorganic carbon.

  20. Effects of mining wastes on a seagrass ecosystem: metal accumulation and bioavailability, seagrass dynamics and associated community structure.

    PubMed

    Marín-Guirao, Lázaro; Atucha, Arnaldo Marín; Barba, Javier Lloret; López, Emma Martínez; Fernández, Antonio J García

    2005-09-01

    Two different Cymodocea nodosa (Ucria) Ascherson beds growing in mining-contaminated sediments were compared with two reference beds in the Mar Menor coastal lagoon. The accumulation of Zn, Pb and Cd in different fractions of the plant, the sediment parameters that regulate the availability of metals, the seabed structure and dynamics of each seagrass bed and its associated macroinvertebrate community were studied. C. nodosa accumulates metals from the sediments and reflects their bioavailability for this seagrass. At each station, the metal content of the rhizomes was lower than that of leaves and roots. The concentration of acid-volatile sulfides does not seem to influence the availability of metals to the seagrass, possibly due to oxygen transport to underground tissues. The highest metal concentration in all the contaminated stations was found in the leaf-biofilm, due to the formation of complexes between metals and the extracellular polymeric substances that form the biofilm. All the seagrass beds were seen to be undergoing expansion, those growing in contaminated sediments accumulating great quantities of metals and showing highest photosynthetic leaf surface area and highest leaf biomass. However, these structural parameters were not seen to be responsible for the differences in the faunal composition observed between contaminated and reference beds. Moreover, the multivariate analysis identified the metal content of leaves, biofilm and sediments as important variables that may be responsible for these differences in faunal composition. In this study we have demonstrated that both the seagrass C. nodosa and the biofilm on the plant leaves may be used as environmental tools in the Mar Menor lagoon. The former is an useful indicator of sediment contamination, whereas the latter seems to be a good sentinel of water quality.

  1. 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

  2. Guidelines for seagrass restoration: importance of habitat selection and donor population, spreading of risks, and ecosystem engineering effects.

    PubMed

    van Katwijk, M M; Bos, A R; de Jonge, V N; Hanssen, L S A M; Hermus, D C R; de Jong, D J

    2009-02-01

    Large-scale losses of seagrass beds have been reported for decades and lead to numerous restoration programs. From worldwide scientific literature and 20 years of seagrass restoration research in the Wadden Sea, we review and evaluate the traditional guidelines and propose new guidelines for seagrass restoration. Habitat and donor selection are crucial: large differences in survival were found among habitats and among donor populations. The need to preferably transplant in historically confirmed seagrass habitats, and to collect donor material from comparable habitats, were underlined by our results. The importance of sufficient genetic variation of donor material and prevention of genetic isolation by distance was reviewed. The spreading of risks among transplantation sites, which differed in habitat characteristics (or among replicate sites), was positively evaluated. The importance of ecosystem engineering was shown in two ways: seagrass self-facilitation and facilitation by shellfish reefs. Seagrass self-facilitative properties may require a large transplantation scale or additional measures.

  3. Spatially explicit feedbacks between seagrass meadow structure, sediment and light: Habitat suitability for seagrass growth

    NASA Astrophysics Data System (ADS)

    Carr, Joel A.; D'Odorico, Paolo; McGlathery, Karen J.; Wiberg, Patricia L.

    2016-07-01

    In shallow coastal bays where nutrient loading and riverine inputs are low, turbidity, and the consequent light environment are controlled by resuspension of bed sediments due to wind-waves and tidal currents. High sediment resuspension and low light environments can limit benthic primary productivity; however, both currents and waves are affected by the presence of benthic plants such as seagrass. This feedback between the presence of benthic primary producers such as seagrass and the consequent light environment has been predicted to induce bistable dynamics locally. However, these vegetated areas influence a larger area than they footprint, including a barren adjacent downstream area which exhibits reduced shear stresses. Here we explore through modeling how the patchy structure of seagrass meadows on a landscape may affect sediment resuspension and the consequent light environment due to the presence of this sheltered region. Heterogeneous vegetation covers comprising a mosaic of randomly distributed patches were generated to investigate the effect of patch modified hydrodynamics. Actual cover of vegetation on the landscape was used to facilitate comparisons across landscape realizations. Hourly wave and current shear stresses on the landscape along with suspended sediment concentration and light attenuation characteristics were then calculated and spatially averaged to examine how actual cover and mean water depth affect the bulk sediment and light environment. The results indicate that an effective cover, which incorporates the sheltering area, has important controls on the distributions of shear stress, suspended sediment, light environment, and consequent seagrass habitat suitability. Interestingly, an optimal habitat occurs within a depth range where, if actual cover is reduced past some threshold, the bulk light environment would no longer favor seagrass growth.

  4. Spatially explicit feedbacks between seagrass meadow structure, sediment and light: Habitat suitability for seagrass growth

    USGS Publications Warehouse

    Carr, Joel; D'Odorico, Paul; McGlathery, Karen; Wiberg, Patricia L.

    2016-01-01

    In shallow coastal bays where nutrient loading and riverine inputs are low, turbidity, and the consequent light environment are controlled by resuspension of bed sediments due to wind-waves and tidal currents. High sediment resuspension and low light environments can limit benthic primary productivity; however, both currents and waves are affected by the presence of benthic plants such as seagrass. This feedback between the presence of benthic primary producers such as seagrass and the consequent light environment has been predicted to induce bistable dynamics locally. However, these vegetated areas influence a larger area than they footprint, including a barren adjacent downstream area which exhibits reduced shear stresses. Here we explore through modeling how the patchy structure of seagrass meadows on a landscape may affect sediment resuspension and the consequent light environment due to the presence of this sheltered region. Heterogeneous vegetation covers comprising a mosaic of randomly distributed patches were generated to investigate the effect of patch modified hydrodynamics. Actual cover of vegetation on the landscape was used to facilitate comparisons across landscape realizations. Hourly wave and current shear stresses on the landscape along with suspended sediment concentration and light attenuation characteristics were then calculated and spatially averaged to examine how actual cover and mean water depth affect the bulk sediment and light environment. The results indicate that an effective cover, which incorporates the sheltering area, has important controls on the distributions of shear stress, suspended sediment, light environment, and consequent seagrass habitat suitability. Interestingly, an optimal habitat occurs within a depth range where, if actual cover is reduced past some threshold, the bulk light environment would no longer favor seagrass growth.

  5. Seagrasses as indicators for coastal trace metal pollution: a global meta-analysis serving as a benchmark, and a Caribbean case study.

    PubMed

    Govers, Laura L; Lamers, Leon P M; Bouma, Tjeerd J; Eygensteyn, Jelle; de Brouwer, Jan H F; Hendriks, A Jan; Huijbers, Chantal M; van Katwijk, Marieke M

    2014-12-01

    Seagrass beds are highly productive coastal ecosystems providing a large array of ecosystem services including fisheries and carbon sequestration. As seagrasses are known to be highly sensitive to anthropogenic forcing, we evaluated the use of trace metal concentrations in seagrasses as bioindicators for trace metal pollution of coastal regions at both global and local scale. We carried out a meta-analysis based on literature data to provide a global benchmark list for trace metal accumulation in seagrasses, which was lacking in literature. We subsequently carried out a case study at the Caribbean islands of Curaçao and Bonaire to test for local-scale differences in trace metal concentrations in seagrasses, and internal metal allocation. The benchmark and local study show that trace metal concentrations in seagrass leaves, regardless of the species, can vary over a 100-1000-fold range, and are related to the level of anthropogenic pressure, making seagrasses highly valuable indicators.

  6. Seagrass Health Modeling and Prediction with NASA Science Data

    NASA Technical Reports Server (NTRS)

    Robinson, Harold D.; Easson, Greg; Slattery, Marc; Anderson, Daniel; Blonski, Slawomir; DeCurtins, Robert; Underwood, Lauren

    2010-01-01

    Previous research has demonstrated that MODIS data products can be used as inputs into the seagrass productivity model developed by Fong and Harwell (1994). To further explore this use to predict seagrass productivity, Moderate Resolution Imaging Spectroradiometer (MODIS) custom data products, including Sea Surface Temperature, Light Attenuation, and Chlorophyll-a have been created for use as model parameter inputs. Coastal researchers can use these MODIS data products and model results in conjunction with historical and daily assessment of seagrass conditions to assess variables that affect the productivity of the seagrass beds. Current monitoring practices involve manual data collection (typically on a quarterly basis) and the data is often insufficient for evaluating the dynamic events that influence seagrass beds. As part of a NASA-funded research grant, the University of Mississippi, is working with researchers at NASA and Radiance Technologies to develop methods to deliver MODIS derived model output for the northern Gulf of Mexico (GOM) to coastal and environmental managers. The result of the project will be a data portal that provides access to MODIS data products and model results from the past 5 years, that includes an automated process to incorporate new data as it becomes available. All model parameters and final output will be available through the use National Oceanic and Atmospheric Administration?s (NOAA) Environmental Research Divisions Data Access Program (ERDDAP) tools as well as viewable using Thematic Realtime Environmental Distributed Data Services (THREDDS) and the Integrated Data Viewer (IDV). These tools provide the ability to create raster-based time sequences of model output and parameters as well as create graphs of model parameters versus time. This tool will provide researchers and coastal managers the ability to analyze the model inputs so that the factors influencing a change in seagrass productivity can be determined over time.

  7. Seagrass status and trends in the northern Gulf of Mexico: 1940-2002

    USGS Publications Warehouse

    Handley, L.; Altsman, D.; DeMay, R.

    2007-01-01

    Over the past century, seagrass habitats from the bays of Texas to the gulf shores of Florida have decreased. Seagrass beds, which are highly dependent on water quality and clarity for survival, are home to a multitude of aquatic plants and animals and a source of economic activity through commercial and recreational fishing and ecotourism. The U.S. Environmental Protection Agency’s Gulf of Mexico Program (GMP) and its partners have made a commitment to restore, enhance, and protect this important ecosystem. As seagrass habitats decrease, the need for information on the causes and effects of seagrass loss, current mapping information, and education on the importance of seagrassess becomes greater. This report is the initial effort of the GMP’s research and restoration plan for seagrasses. The purpose of this report is to provide scientists, managers, and citizens with valuable baseline information on the status and trends of seagrasses in coastal waters of the Gulf of Mexico. Within the northern Gulf of Mexico region, 14 individual estuarine systems where seagrasses occur, as well as statewide summaries for Texas, Louisiana, Mississippi, Alabama, and Florida, are examined in this study. Each estuarine system is detailed in vignettes that address current and historical extent and quality of seagrasses, seagrass mapping and monitoring, causes of status change, restoration and enhancement activities, background information for the entire study area as well as the subareas for study, and the methodology employed to analyze and document the historical trends and current status of seagrasses. The systems, moving from west to east, include the Laguna Madre, Texas Coastal Bend region, and Galveston Bay in Texas; the Chandeleur Islands in Louisiana; the Mississippi Sound; and Perdido Bay, Pensacola/Escambia Bay, Choctawhatchee Bay, St. Andrew Bay, Florida’s Big Bend region, Tampa Bay/St. Joseph Sound, Sarasota Bay, Greater Charlotte Harbor, and Florida Bay in Florida

  8. Using modelling to predict impacts of sea level rise and increased turbidity on seagrass distributions in estuarine embayments

    NASA Astrophysics Data System (ADS)

    Davis, Tom R.; Harasti, David; Smith, Stephen D. A.; Kelaher, Brendan P.

    2016-11-01

    Climate change induced sea level rise will affect shallow estuarine habitats, which are already under threat from multiple anthropogenic stressors. Here, we present the results of modelling to predict potential impacts of climate change associated processes on seagrass distributions. We use a novel application of relative environmental suitability (RES) modelling to examine relationships between variables of physiological importance to seagrasses (light availability, wave exposure, and current flow) and seagrass distributions within 5 estuarine embayments. Models were constructed separately for Posidonia australis and Zostera muelleri subsp. capricorni using seagrass data from Port Stephens estuary, New South Wales, Australia. Subsequent testing of models used independent datasets from four other estuarine embayments (Wallis Lake, Lake Illawarra, Merimbula Lake, and Pambula Lake) distributed along 570 km of the east Australian coast. Relative environmental suitability models provided adequate predictions for seagrass distributions within Port Stephens and the other estuarine embayments, indicating that they may have broad regional application. Under the predictions of RES models, both sea level rise and increased turbidity are predicted to cause substantial seagrass losses in deeper estuarine areas, resulting in a net shoreward movement of seagrass beds. Seagrass species distribution models developed in this study provide a valuable tool to predict future shifts in estuarine seagrass distributions, allowing identification of areas for protection, monitoring and rehabilitation.

  9. Brevetoxin persistence in sediments and seagrass epiphytes of east Florida coastal waters.

    PubMed

    Hitchcock, Gary L; Fourqurean, James W; Drake, Jeana L; Mead, Ralph N; Heil, Cynthia A

    2012-01-01

    A bloom of Karenia brevis Davis developed in September 2007 near Jacksonville, Florida and subsequently progressed south through east Florida coastal waters and the Atlantic Intracoastal Waterway (ICW). Maximum cell abundances exceeded 10(6) cells L(-1) through October in the northern ICW between Jacksonville and the Indian River Lagoon. The bloom progressed further south during November, and terminated in December 2007 at densities of 10(4) cells L(-1) in the ICW south of Jupiter Inlet, Florida. Brevetoxins were subsequently sampled in sediments and seagrass epiphytes in July and August 2008 in the ICW. Sediment brevetoxins occurred at concentrations of 11-15 ng PbTx-3 equivalents (g dry wt sediment)(-1) in three of five basins in the northern ICW during summer 2008. Seagrass beds occur south of the Mosquito Lagoon in the ICW. Brevetoxins were detected in six of the nine seagrass beds sampled between the Mosquito Lagoon and Jupiter Inlet at concentrations of 6-18 ng (g dry wt epiphytes)(-1). The highest brevetoxins concentrations were found in sediments near Patrick Air Force Base at 89 ng (g dry wt sediment)(-1). In general, brevetoxins occurred in either seagrass epiphytes or sediments. Blades of the resident seagrass species have a maximum life span of less than six months, so it is postulated that brevetoxins could be transferred between epibenthic communities of individual blades in seagrass beds. The occurrence of brevetoxins in east Florida coast sediments and seagrass epiphytes up to eight months after bloom termination supports observations from the Florida west coast that brevetoxins can persist in marine ecosystems in the absence of sustained blooms. Furthermore, our observations show that brevetoxins can persist in sediments where seagrass communities are absent.

  10. Food-Web Structure of Seagrass Communities across Different Spatial Scales and Human Impacts

    PubMed Central

    Coll, Marta; Schmidt, Allison; Romanuk, Tamara; Lotze, Heike K.

    2011-01-01

    Seagrass beds provide important habitat for a wide range of marine species but are threatened by multiple human impacts in coastal waters. Although seagrass communities have been well-studied in the field, a quantification of their food-web structure and functioning, and how these change across space and human impacts has been lacking. Motivated by extensive field surveys and literature information, we analyzed the structural features of food webs associated with Zostera marina across 16 study sites in 3 provinces in Atlantic Canada. Our goals were to (i) quantify differences in food-web structure across local and regional scales and human impacts, (ii) assess the robustness of seagrass webs to simulated species loss, and (iii) compare food-web structure in temperate Atlantic seagrass beds with those of other aquatic ecosystems. We constructed individual food webs for each study site and cumulative webs for each province and the entire region based on presence/absence of species, and calculated 16 structural properties for each web. Our results indicate that food-web structure was similar among low impact sites across regions. With increasing human impacts associated with eutrophication, however, food-web structure show evidence of degradation as indicated by fewer trophic groups, lower maximum trophic level of the highest top predator, fewer trophic links connecting top to basal species, higher fractions of herbivores and intermediate consumers, and higher number of prey per species. These structural changes translate into functional changes with impacted sites being less robust to simulated species loss. Temperate Atlantic seagrass webs are similar to a tropical seagrass web, yet differed from other aquatic webs, suggesting consistent food-web characteristics across seagrass ecosystems in different regions. Our study illustrates that food-web structure and functioning of seagrass habitats change with human impacts and that the spatial scale of food-web analysis

  11. Food-web structure of seagrass communities across different spatial scales and human impacts.

    PubMed

    Coll, Marta; Schmidt, Allison; Romanuk, Tamara; Lotze, Heike K

    2011-01-01

    Seagrass beds provide important habitat for a wide range of marine species but are threatened by multiple human impacts in coastal waters. Although seagrass communities have been well-studied in the field, a quantification of their food-web structure and functioning, and how these change across space and human impacts has been lacking. Motivated by extensive field surveys and literature information, we analyzed the structural features of food webs associated with Zostera marina across 16 study sites in 3 provinces in Atlantic Canada. Our goals were to (i) quantify differences in food-web structure across local and regional scales and human impacts, (ii) assess the robustness of seagrass webs to simulated species loss, and (iii) compare food-web structure in temperate Atlantic seagrass beds with those of other aquatic ecosystems. We constructed individual food webs for each study site and cumulative webs for each province and the entire region based on presence/absence of species, and calculated 16 structural properties for each web. Our results indicate that food-web structure was similar among low impact sites across regions. With increasing human impacts associated with eutrophication, however, food-web structure show evidence of degradation as indicated by fewer trophic groups, lower maximum trophic level of the highest top predator, fewer trophic links connecting top to basal species, higher fractions of herbivores and intermediate consumers, and higher number of prey per species. These structural changes translate into functional changes with impacted sites being less robust to simulated species loss. Temperate Atlantic seagrass webs are similar to a tropical seagrass web, yet differed from other aquatic webs, suggesting consistent food-web characteristics across seagrass ecosystems in different regions. Our study illustrates that food-web structure and functioning of seagrass habitats change with human impacts and that the spatial scale of food-web analysis

  12. Community structure and biomass distribution of seagrasses and macrofauna in the flores sea, Indonesia

    NASA Astrophysics Data System (ADS)

    Nienhuis, P. H.; Coosen, J.; Kiswara, W.

    In several locations in the Flores Sea region the community structure and the biomass distribution of seagrasses were studied along transects perpendicular to the shoreline. The share of each species within a sample plot was estimated, divided in above- and below-ground biomass. Statistics regarding substrate coverage, shoot density and leaf-area index were sampled. A standard relation was calculated between seagrass dry weight, ash-free dry weight and organic carbon content. The biotic data were related to environmental factors: DOC and nutrients in the water, salinity, tidal amplitude, sediment composition. A relation was estimated between bottom coverage of seagrasses and standing stock. Further calculations of biomass-production ratios allow a quick and rough estimate of seagrass productivity. Maximum above-ground biomass values (500-700 g AFDW·m -2) together with qualitative data indicate resource (= space) partitioning among the component seagrasses within a community, and suggest a carrying capacity of the reefflat habitat for seagrass density and biomass. A tentative model was constructed, starting from a constant, non-distributed multispecies vegetation in the lower intertidal and subtidal zone on sand and coral rubble, and moving into several suboptimal situations. The upper shore carries an impoverished, constrained vegetation (irregular tides, desiccation, harvesting). Sediment reworking by animals and physical displacement of sand disturbs the vegetation and favours pioneer species. Muddy habitats bordering mangroves carry monospecific stands showing extremely high biomass ( e.g. below-ground Enhalus acoroides 3500 g AFDW·m -2). Thalassia hemprichii and Enhalus acoroides are the most constant species in all habitats mentioned. Macrofauna biomass within the seagrass beds fluctuated widely (maximum values 50-70 g AFDW·m -2 in mixed seagrass vegetations) and only a weak relation between benthic macrofauna biomass and seagrass community structure and

  13. Causes of seasonal and decadal variability in a tropical seagrass seascape (Reunion Island, south western Indian Ocean)

    NASA Astrophysics Data System (ADS)

    Cuvillier, A.; Villeneuve, N.; Cordier, E.; Kolasinski, J.; Maurel, L.; Farnier, N.; Frouin, P.

    2017-01-01

    While seagrass meadows are considered as vulnerable or declining habitats worldwide, facing many natural and anthropogenic pressures, the opposite trend is suggested by this study in Reunion Island (Indian Ocean). Located at the benthos-pelagos interface, seagrass beds are critical coastal habitats and can be used as relevant health indicators for larger marine ecosystems or land-sea continuum. In order to determine which are the factors driving seagrass ecosystems health it is essential to quantify their seascape pattern fluctuations. The long-term (over 65 years) and seasonal scale variability was assessed in the monospecific Syringodium isoetifolium seagrass bed seascape at the Ermitage/La Saline fringing reef using aerial photographs and field measurements. Both long-term and short-term scales have been informative and both types of monitoring appear as useful tools for seagrass ecosystem management. Strong variations in seagrass coverage were observed in the 16 rasters analyzed from years 1950-2015, the magnitude order was however similar to the one observed at the recent seasonal scale (up to 2016 m2 gained or 4863 m2 lost over few months at site scale). Seascape pattern analysis revealed that physical factors (swell events, cyclones) had a major impact on the ocean-exposed site with varying impact degree depending on frequency, duration and intensity. Biotic (herbivory) or anthropogenic (grubbing, nutrient inputs) factors were also identified to influence the structural shape, fragmentation, or disappearance of seagrass beds. Further work is required to better quantify the effect of each single factor, a difficult task due to their combined expression. At the reef scale, these results showed a positive correlation between seagrass beds and inner reef flat coverage suggesting that common factors drive these highly resilient ecosystems.

  14. Seagrass colonization: Knock-on effects on zoobenthic community, populations and individual health

    NASA Astrophysics Data System (ADS)

    Tu Do, V.; de Montaudouin, Xavier; Lavesque, Nicolas; Blanchet, Hugues; Guyard, Hervé

    2011-12-01

    This study provided evidence that Zostera noltii presence affects macrofauna community structure independently from median sediment grain-size and that the notion of ecosystem health is rather subjective: in the present case, we recorded "good health" in terms of seagrass development, "no impact" in terms of macrobenthic biotic indices and "negative effect" for a given key-population. The occurrence and development of a Z. noltii seagrass bed was surveyed at Banc d'Arguin, Arcachon Bay (France), to estimate the modification of the macrozoobenthic community and of the dynamics of a key-population for the local ecosystem, - the cockle Cerastoderma edule. Even though median grain-size of the sediment decreased only at the very end of the survey, i.e. when seagrass totally invaded the area, most of the macrofauna community characteristics (such as abundance and biomass) increased as soon as Z. noltii patches appeared. The structure of the macrofauna community also immediately diverged between sand and seagrass habitats, without however modifying the tested biotic indices (BENTIX, BOPA, AMBI). The health of the cockle population (growth, abundance, recruitment) was impacted by seagrass development. Related parasite communities slowly diverged between habitats, with more parasites in the cockles from seagrass areas. However, the number of parasites per cockle was always insufficient to alter cockle fitness.

  15. Recovery of floral and faunal communities after placement of dredged material on seagrasses in Laguna Madre, Texas

    NASA Astrophysics Data System (ADS)

    Sheridan, P.

    2004-03-01

    The objectives of this project were to determine how long alterations in habitat characteristics and use by fishery and forage organisms were detectable at dredged material placement sites in Laguna Madre, Texas. Water, sediment, seagrass, benthos, and nekton characteristics were measured and compared among newly deposited sediments and nearby and distant seagrasses each fall and spring over three years. Over this period, 75% of the estimated total surface area of the original deposits was either re-vegetated by seagrass or dispersed by winds and currents. Differences in water and sediment characteristics among habitat types were mostly detected early in the study. There were signs of steady seagrass re-colonization in the latter half of the study period, and mean seagrass coverage of deposits had reached 48% approximately three years after dredging. Clovergrass Halophila engelmannii was the initial colonist, but shoalgrass Halodule wrightii predominated after about one year. Densities of annelids and non-decapod crustaceans were generally significantly greater in close and distant seagrass habitats than in dredged material habitat, whereas densities of molluscs were not significantly related to habitat type. Nekton (fish and decapod) densities were almost always significantly greater in the two seagrass habitats than in dredged material deposits. Benthos and nekton communities in dredged material deposits were distinct from those in seagrass habitats. Recovery from dredged material placement was nearly complete for water column and sediment components after 1.5 to 3 years, but recovery of seagrasses, benthos, and nekton was predicted to take 4 to 8 years. The current 2 to 5 years dredging cycle virtually insures no time for ecosystem recovery before being disturbed again. The only way to ensure permanent protection of the high primary and secondary productivity of seagrass beds in Laguna Madre from acute and chronic effects of maintenance dredging, while ensuring

  16. Decreasing seagrass density negatively influences associated fauna

    PubMed Central

    McCloskey, Rosemary M.

    2015-01-01

    Seagrass meadows globally are disappearing at a rapid rate with physical disturbances being one of the major drivers of this habitat loss. Disturbance of seagrass can lead to fragmentation, a reduction in shoot density, canopy height and coverage, and potentially permanent loss of habitat. Despite being such a widespread issue, knowledge of how such small scale change affects the spatial distribution and abundances of motile fauna remains limited. The present study investigated fish and macro faunal community response patterns to a range of habitat variables (shoot length, cover and density), including individual species habitat preferences within a disturbed and patchy intertidal seagrass meadow. Multivariate analysis showed a measurable effect of variable seagrass cover on the abundance and distribution of the fauna, with species specific preferences to both high and low seagrass cover seagrass. The faunal community composition varied significantly with increasing/decreasing cover. The faunal species composition of low cover seagrass was more similar to sandy control plots than to higher cover seagrass. Shannon Wiener Diversity (H′) and species richness was significantly higher in high cover seagrass than in low cover seagrass, indicating increasing habitat value as density increases. The results of this study underline how the impacts of small scale disturbances from factors such as anchor damage, boat moorings and intertidal vehicle use on seagrass meadows that reduce shoot density and cover can impact upon associated fauna. These impacts have negative consequences for the delivery of ecosystem services such as the provision of nursery habitat. PMID:26137432

  17. Decreasing seagrass density negatively influences associated fauna.

    PubMed

    McCloskey, Rosemary M; Unsworth, Richard K F

    2015-01-01

    Seagrass meadows globally are disappearing at a rapid rate with physical disturbances being one of the major drivers of this habitat loss. Disturbance of seagrass can lead to fragmentation, a reduction in shoot density, canopy height and coverage, and potentially permanent loss of habitat. Despite being such a widespread issue, knowledge of how such small scale change affects the spatial distribution and abundances of motile fauna remains limited. The present study investigated fish and macro faunal community response patterns to a range of habitat variables (shoot length, cover and density), including individual species habitat preferences within a disturbed and patchy intertidal seagrass meadow. Multivariate analysis showed a measurable effect of variable seagrass cover on the abundance and distribution of the fauna, with species specific preferences to both high and low seagrass cover seagrass. The faunal community composition varied significantly with increasing/decreasing cover. The faunal species composition of low cover seagrass was more similar to sandy control plots than to higher cover seagrass. Shannon Wiener Diversity (H') and species richness was significantly higher in high cover seagrass than in low cover seagrass, indicating increasing habitat value as density increases. The results of this study underline how the impacts of small scale disturbances from factors such as anchor damage, boat moorings and intertidal vehicle use on seagrass meadows that reduce shoot density and cover can impact upon associated fauna. These impacts have negative consequences for the delivery of ecosystem services such as the provision of nursery habitat.

  18. Distribution of fish in seagrass, mangroves and coral reefs: life-stage dependent habitat use in Honduras.

    PubMed

    Jaxion-Harm, Jessica; Saunders, James; Speight, Martin R

    2012-06-01

    Many coral reef fish exhibit habitat partitioning throughout their lifetimes. Such patterns are evident in the Caribbean where research has been predominantly conducted in the Eastern region. This work addressed the paucity of data regarding Honduran reef fish distribution in three habitat types (seagrass, mangroves, and coral reefs), by surveying fish on the islands of Utila and Cayos Cochinos off the coast of Honduras (part of the Mesoamerican barrier reef). During July 2nd - Aug 27th 2007 and June 22nd - Aug 17th, 2008, visual surveys (SCUBA and snorkel) were performed in belt transects in different areas: eleven coral reef, six seagrass beds, and six mangroves sites. Juvenile densities and total habitat surface area were used to calculate nursery value of seagrass and mangroves. A total of 113 fish species from 32 families were found during underwater surveys. Multi-dimensional analyses revealed distinct clusters of fish communities in each habitat type by separating fish associated with seagrass beds, mangroves, and coral reefs. Coral reefs showed the highest mean fish species richness and were dominated by adult fish, while juvenile fish characterized seagrass beds and mangrove sites. Habitat use differed widely at the fish species level. Scarus iseri (Striped Parrotfish), the most abundant fish in this study, were found in all three habitat types, while Lutjanus apodus (Schoolmaster Snapper) juveniles were located primarily in mangroves before migrating to coral reefs. Many species used seagrass beds and mangroves as nurseries; however, the nursery value could not be generalized at the family level. Furthermore, for some fish species, nursery value varied between islands and sites. Our results suggest that connectivity of seagrass, mangrove, and coral reef sites at a species and site levels, should be taken into consideration when implementing policy and conservation practices.

  19. INTRACELLULAR COLONIZATION OF SEAGRASS ROOTS BY ACETOGENIC AND SULFIDOGENIC BACTERIA

    EPA Science Inventory

    The contribution of seagrasses to the stability and fertility of estuarine ecosystems is well established. Loss of seagrasses in recent years to disease and coastal development underscores the importance of understanding the microbial ecology of seagrasses, and the possible roles...

  20. NASA Satellite Data for Seagrass Health Modeling and Monitoring

    NASA Technical Reports Server (NTRS)

    Spiering, Bruce A.; Underwood, Lauren; Ross, Kenton

    2011-01-01

    Time series derived information for coastal waters will be used to provide input data for the Fong and Harwell model. The current MODIS land mask limits where the model can be applied; this project will: a) Apply MODIS data with resolution higher than the standard products (250-m vs. 1-km). b) Seek to refine the land mask. c) Explore nearby areas to use as proxies for time series directly over the beds. Novel processing approaches will be leveraged from other NASA projects and customized as inputs for seagrass productivity modeling

  1. Carbon storage in seagrass soils: long-term nutrient history exceeds the effects of near-term nutrient enrichment

    NASA Astrophysics Data System (ADS)

    Armitage, A. R.; Fourqurean, J. W.

    2015-10-01

    The carbon sequestration potential in coastal soils is linked to aboveground and belowground plant productivity and biomass, which in turn, is directly and indirectly influenced by nutrient input. We evaluated the influence of long-term and near-term nutrient input on aboveground and belowground carbon accumulation in seagrass beds, using a nutrient enrichment (nitrogen and phosphorus) experiment embedded within a naturally occurring, long-term gradient of phosphorus availability within Florida Bay (USA). We measured organic carbon stocks in soils and above- and belowground seagrass biomass after 17 months of experimental nutrient addition. At the nutrient-limited sites, phosphorus addition increased the carbon stock in aboveground seagrass biomass by more than 300 %; belowground seagrass carbon stock increased by 50-100 %. Soil carbon content slightly decreased (~ 10 %) in response to phosphorus addition. There was a strong but non-linear relationship between soil carbon and Thalassia testudinum leaf nitrogen: phosphorus (N : P) or belowground seagrass carbon stock. When seagrass leaf N : P exceeded a threshold of 75 : 1, or when belowground seagrass carbon stock was less than 100 g m-2, there was less than 3 % organic carbon in the sediment. Despite the marked difference in soil carbon between phosphorus-limited and phosphorus-replete areas of Florida Bay, all areas of the bay had relatively high soil carbon stocks near or above the global median of 1.8 % organic carbon. The relatively high carbon content in the soils indicates that seagrass beds have extremely high carbon storage potential, even in nutrient-limited areas with low biomass or productivity.

  2. Carbon storage in seagrass soils: long-term nutrient history exceeds the effects of near-term nutrient enrichment

    NASA Astrophysics Data System (ADS)

    Armitage, A. R.; Fourqurean, J. W.

    2016-01-01

    The carbon sequestration potential in coastal soils is linked to aboveground and belowground plant productivity and biomass, which in turn, is directly and indirectly influenced by nutrient input. We evaluated the influence of long-term and near-term nutrient input on aboveground and belowground carbon accumulation in seagrass beds, using a nutrient enrichment (nitrogen and phosphorus) experiment embedded within a naturally occurring, long-term gradient of phosphorus availability within Florida Bay (USA). We measured organic carbon stocks in soils and above- and belowground seagrass biomass after 17 months of experimental nutrient addition. At the nutrient-limited sites, phosphorus addition increased the carbon stock in aboveground seagrass biomass by more than 300 %; belowground seagrass carbon stock increased by 50-100 %. Soil carbon content slightly decreased ( ˜ 10 %) in response to phosphorus addition. There was a strong but non-linear relationship between soil carbon and Thalassia testudinum leaf nitrogen : phosphorus (N : P) or belowground seagrass carbon stock. When seagrass leaf N : P exceeded an approximate threshold of 75 : 1, or when belowground seagrass carbon stock was less than 100 g m-2, there was less than 3 % organic carbon in the sediment. Despite the marked difference in soil carbon between phosphorus-limited and phosphorus-replete areas of Florida Bay, all areas of the bay had relatively high soil carbon stocks near or above the global median of 1.8 % organic carbon. The relatively high carbon content in the soils indicates that seagrass beds have extremely high carbon storage potential, even in nutrient-limited areas with low biomass or productivity.

  3. [Hurricane Paloma's effects on seagrasses along Jardines de la Reina Archipelago, Cuba].

    PubMed

    Guimarais, Mayrene; Zúñiga, Adán; Pina, Fabián; Matos, Felipe

    2013-09-01

    Seagrasses are one of the most important coastal ecosystems since they promote organic matter flow, nutrient cycling, food availability and refuge. Until now, reports on damages caused by storms and hurricanes on seagrass beds are uncommon and highly variable. The seagrass meadows of the East end of Jardines de la Reina archipelago were surveyed from Nov. 29th to Dec. 5th of 2008, in order to determinate the effects from the passing of Hurricane Paloma: a category three storm on the Saffir-Simpsom scale. A rapid field assessment of the affected areas was carried out using the manta tow technique. In six sites, seagrass was quantitatively evaluated using a 15cm diameter core (four sampling units per site) and shoot density was calculated. Remote sensing techniques were used to estimate seagrass cover. To estimate the percentage of affected areas, a Region of Interest (ROI) was first created over a Landsat image. The percentage of seagrass affected within the ROI was estimated through direct georeferentiation of the contours of the damaged area and with a comparison to the total seagrass extension. To find possible explanations for damages, a false colour image was created using the near infrared band, to highlight the differences between emerged and submerged zones. The direction of winds was estimated using ArcGis 9.2 creating circular buffers, from the centre of the hurricane and generating lines tangent to the buffers. Seagrass in the region was dominated by the angiosperm Thalassia testudinum. Regional mean density was 1 321 +/- 721 shoots/m2, a value regarded as high for the Caribbean area. Seagrass meadows were partly affected by sediment accumulation on the shoots of T. testudinum and uprooting rhizomes. The 7.6 km2 disturbed area represented 1% of the total seagrass area. Other sites, closer to the centre of the hurricane, did not show any damages on the marine vegetation. The keys location with respect to the hurricane track was the most likely cause of the

  4. Seasonality in vegetation biometrics and its effects on sediment characteristics and meiofauna in Baltic seagrass meadows

    NASA Astrophysics Data System (ADS)

    Jankowska, Emilia; Włodarska-Kowalczuk, Maria; Kotwicki, Lech; Balazy, Piotr; Kuliński, Karol

    2014-02-01

    Seagrass meadows can act as ecosystem engineers, i.e., organisms that modify the availability of resources to other organisms. However, their possible positive impacts depend on the characteristics of the vegetation, and these can vary strongly seasonally. This study assesses seasonal variability in macrophyte taxonomic composition and seagrass biometrics in the temperate Baltic Sea eelgrass meadows. We hypothesize that the anticipated strong seasonality in vegetation cover induces parallel seasonal changes in seagrass engineering effects as indicated by changes in sediment characteristics and meiozoobenthic abundance, composition and diversity. Macrophytes, sediments, and fauna were sampled at two locations in the Puck Bay from vegetated bottoms and bare sands five times in one year. Zostera marina vegetation occurred throughout the year and showed strong seasonality with the highest values of shoot density, leaf length, and biomass in July (202.3 ± 30.0 95% CI shoots m-2) and the lowest in March (55.4 ± 15.0 shoots m-2). POC was significantly higher in vegetated sands, and these effects were evident throughout the study period regardless of variability in macrophyte vegetation. The density and diversity of meiofauna did not differ between the seagrass beds and bare sands even in summer months when vegetation was best developed. The lack of an effect of the seagrass meadows on the meiofauna can be explained by the relatively low shoot density and biomass of the studied seagrass meadows and/or higher macrobenthic predation on the vegetated bottom compared to bare sands. However, both the canopies of macrophytes and the effects of the vegetation on benthic systems could increase substantially over the course of the gradual, natural restoration of the seagrass meadows.

  5. Ecological structure and function differs between habitats dominated by seagrasses and green seaweeds.

    PubMed

    Tuya, Fernando; Png-Gonzalez, Lydia; Riera, Rodrigo; Haroun, Ricardo; Espino, Fernando

    2014-07-01

    Marine vegetated habitats, e.g. seagrass meadows, deliver essential functions and services to coastal ecosystems and human welfare. Impacts induced by humans, however, have facilitated the replacement of seagrasses by alternative vegetation, e.g. green rhizophytic seaweeds. The implications of habitat shifts for ecosystem attributes and processes and the services they deliver remain poorly known. In this study, we compared ecosystem structure and function between Cymodocea nodosa seagrass meadows and bottoms dominated by Caulerpa prolifera, a green, native, rhizophytic seaweed, through 5 ecological proxies: (i) primary production (via community metabolism), (ii) composition and abundance of epifauna (a proxy for provision of habitat for epifauna), composition and abundance of (iii) small-sized (juvenile) and (iv) large-sized (adult) fishes (proxies for provision of habitat for fishes), and (v) sediment retention (a proxy for sediment stabilization). Four of these proxies were greater in C. nodosa seagrass meadows than in C. prolifera beds: gross primary productivity (∼1.4 times), the total abundance, species density and biomass of small-sized fishes (∼2.1, 1.3 and 1.3 times, respectively), the total abundance and species density of large-sized fishes (∼3.6 and 1.5 times, respectively), and sediment stabilization (∼1.4 times). In contrast, the total abundance and species density of epifauna was larger (∼3.1 and 1.7 times, respectively) in C. prolifera than in C. nodosa seagrass beds. These results suggest that ecosystem structure and function may differ if seagrasses are replaced by green rhizophytic seaweeds. Importantly, ecosystem functions may not be appropriate surrogates for one another. As a result, assessments of ecosystem services associated with ecosystem functions cannot be based on exclusively one service that is expected to benefit other services.

  6. Comparison of zooplankton abundance and community in seagrass and non-seagrass areas of Merambong shoal

    NASA Astrophysics Data System (ADS)

    Azmi, Afiq Auji; Yoshida, Teruaki; Toda, Tatsuki; Ross, Othman bin Haji; Cob, Zaidi Che

    2016-11-01

    A zooplankton comparison study of Merambong shoal's seagrass and non-seagrass area was conducted from April 2013 to October 2014. Sampling was conducted monthly at fixed stations by horizontal tows of a 140 µm plankton net. Mean temperature was significantly higher during the south-west (SW) monsoon at both stations. Salinity and Chlorophyll a concentrations were not significantly different between the monsoons for both stations. However, Chlorophyll a concentrations were significantly higher in the seagrass compared to non-seagrass station. Mean zooplankton abundance was 1.32-fold higher in the non-seagrass area (4006.5±1990.5 ind/mł) than the seagrass area (3030.1± 855.6 ind/mł), despite overall higher Chlorophyll a levels in the seagrass station. At the seagrass station, the dominant copepods Paracalanus and Parvocalanus abundances were significantly higher (p<0.01, Mann-Whitney) during the SW monsoon, while Euterpina was significantly lower (p<0.04, Mann-Whitney). The non-seagrass station also showed a similar trend where the dominant copepods Paracalanus and Parvocalanus abundances were significantly higher in the SW monsoon (p<0.02, Mann-Whitney). Higher percentage of meroplankton was recorded during the study period in seagrass area with 11.6 %, 1.5 fold of non-seagrass area.

  7. The movement ecology of seagrasses.

    PubMed

    McMahon, Kathryn; van Dijk, Kor-Jent; Ruiz-Montoya, Leonardo; Kendrick, Gary A; Krauss, Siegfried L; Waycott, Michelle; Verduin, Jennifer; Lowe, Ryan; Statton, John; Brown, Eloise; Duarte, Carlos

    2014-11-22

    A movement ecology framework is applied to enhance our understanding of the causes, mechanisms and consequences of movement in seagrasses: marine, clonal, flowering plants. Four life-history stages of seagrasses can move: pollen, sexual propagules, vegetative fragments and the spread of individuals through clonal growth. Movement occurs on the water surface, in the water column, on or in the sediment, via animal vectors and through spreading clones. A capacity for long-distance dispersal and demographic connectivity over multiple timeframes is the novel feature of the movement ecology of seagrasses with significant evolutionary and ecological consequences. The space-time movement footprint of different life-history stages varies. For example, the distance moved by reproductive propagules and vegetative expansion via clonal growth is similar, but the timescales range exponentially, from hours to months or centuries to millennia, respectively. Consequently, environmental factors and key traits that interact to influence movement also operate on vastly different spatial and temporal scales. Six key future research areas have been identified.

  8. The movement ecology of seagrasses

    PubMed Central

    McMahon, Kathryn; van Dijk, Kor-jent; Ruiz-Montoya, Leonardo; Kendrick, Gary A.; Krauss, Siegfried L.; Waycott, Michelle; Verduin, Jennifer; Lowe, Ryan; Statton, John; Brown, Eloise; Duarte, Carlos

    2014-01-01

    A movement ecology framework is applied to enhance our understanding of the causes, mechanisms and consequences of movement in seagrasses: marine, clonal, flowering plants. Four life-history stages of seagrasses can move: pollen, sexual propagules, vegetative fragments and the spread of individuals through clonal growth. Movement occurs on the water surface, in the water column, on or in the sediment, via animal vectors and through spreading clones. A capacity for long-distance dispersal and demographic connectivity over multiple timeframes is the novel feature of the movement ecology of seagrasses with significant evolutionary and ecological consequences. The space–time movement footprint of different life-history stages varies. For example, the distance moved by reproductive propagules and vegetative expansion via clonal growth is similar, but the timescales range exponentially, from hours to months or centuries to millennia, respectively. Consequently, environmental factors and key traits that interact to influence movement also operate on vastly different spatial and temporal scales. Six key future research areas have been identified. PMID:25297859

  9. Temporal patterns in coral reef, seagrass and mangrove communities from Chengue bay CARICOMP site (Colombia): 1993-2008.

    PubMed

    Rodríguez-Ramírez, Alberto; Garzón-Ferreira, Jaime; Batista-Morales, Angélica; Gil, Diego L; Gómez-López, Diana Isabel; Gómez-Campo, Kelly; López-Londoño, Tomás; Navas-Camacho, Raúl; Reyes-Nivia, María Catalina; Vega-Sequeda, Johanna

    2010-10-01

    Few monitoring programs have simultaneously assessed the dynamics of linked marine ecosystems (coral reefs, seagrass beds and mangroves) to document their temporal and spatial variability. Based on CARICOMP protocol we evaluated permanent stations in coral reefs, seagrass beds and mangroves from 1993 to 2008 in Chengue Bay at the Tayrona Natural Park, Colombian Caribbean. Overall, the studied ecosystems showed a remarkable stability pattern over the monitoring period. While there were annual variations in coral reefs (coral cover) and mangroves (litterfall) caused by hurricane Lenny in 1999, particular trends in seagrass (leaf area index and leaf productivity) appear to reflect the natural variability in this ecosystem. We suggest that monitoring sites at the three marine ecosystems had in general a healthy development in the last 16 years. Our results are critical to locally improve the management strategies (Tayrona Natural Park) and to understand the long-term dynamics of closely associated marine ecosystems in the Caribbean.

  10. LINKS BETWEEN MARSH, NONVEGETATED, AND SEAGRASS HABITATS IN A PRISTINE VIRGINIA SYSTEM

    EPA Science Inventory

    Abstract: We describe habitat linkages in a narrow, contiguous marsh-nonvegetated seagrass system as is found bordering many undeveloped shorelines. Nekton were quantitatively sampled in eight spatial/tidal subhabitats on a Spartina-nonvegetated- Ruppia gradient using 1.75 m2 dro...

  11. Seagrasses and the Coastal Marine Environment

    ERIC Educational Resources Information Center

    Phillips, Ronald C.

    1978-01-01

    Coastal ecosystems are the most highly productive in the world. This article discusses seagrasses, major coastal producers, and provides information on their ecology, productivity, position in food chains, and role in sediment stabilization. Recent attempts to restore seagrasses in areas of massive kills are described. (MA)

  12. SEAGRASS AND CDOM IN THE FLORIDA KEYS

    EPA Science Inventory

    Seagrasses play a variety of important ecological roles in coastal ecosystems. Here we present evidence that seagrass detritus from the widespread species, Thalassia testudinum, is an important source of ocean color and UV-protective substances in a low latitude coastal shelf reg...

  13. Understanding uncertainty in seagrass injury recovery: an information-theoretic approach.

    PubMed

    Uhrin, Amy V; Kenworthy, W Judson; Fonseca, Mark S

    2011-06-01

    Vessel groundings cause severe, persistent gaps in seagrass beds. Varying degrees of natural recovery have been observed for grounding injuries, limiting recovery prediction capabilities, and therefore, management's ability to focus restoration efforts where natural recovery is unlikely. To improve our capacity for predicting seagrass injury recovery, we used an information-theoretic approach to evaluate the relative contribution of specific injury attributes to the natural recovery of 30 seagrass groundings in Florida Keys National Marine Sanctuary, Florida, USA. Injury recovery was defined by three response variables examined independently: (1) initiation of seagrass colonization, (2) areal contraction, and (3) sediment in-filling. We used a global model and all possible subsets for four predictor variables: (1) injury age, (2) original injury volume, (3) original injury perimeter-to-area ratio, and (4) wave energy. Successional processes were underway for many injuries with fast-growing, opportunistic seagrass species contributing most to colonization. The majority of groundings that exhibited natural seagrass colonization also exhibited areal contraction and sediment in-filling. Injuries demonstrating colonization, contraction, and in-filling were on average older and smaller, and they had larger initial perimeter-to-area ratios. Wave energy was highest for colonizing injuries. The information-theoretic approach was unable to select a single "best" model for any response variable. For colonization and contraction, injury age had the highest relative importance as a predictor variable; wave energy appeared to be associated with second-order effects, such as sediment in-filling, which in turn, facilitated seagrass colonization. For sediment in-filling, volume and perimeter-to-area ratio had similar relative importance as predictor variables with age playing a lesser role than seen for colonization and contraction. Our findings confirm that these injuries

  14. Variability of sedimentary organic carbon in patchy seagrass landscapes.

    PubMed

    Ricart, Aurora M; York, Paul H; Rasheed, Michael A; Pérez, Marta; Romero, Javier; Bryant, Catherine V; Macreadie, Peter I

    2015-11-15

    Seagrass ecosystems, considered among the most efficient carbon sinks worldwide, encompass a wide variety of spatial configurations in the coastal landscape. Here we evaluated the influence of the spatial configuration of seagrass meadows at small scales (metres) on carbon storage in seagrass sediments. We intensively sampled carbon stocks and other geochemical properties (δ(13)C, particle size, depositional fluxes) across seagrass-sand edges in a Zostera muelleri patchy seagrass landscape. Carbon stocks were significantly higher (ca. 20%) inside seagrass patches than at seagrass-sand edges and bare sediments. Deposition was similar among all positions and most of the carbon was from allochthonous sources. Patch level attributes (e.g. edge distance) represent important determinants of the spatial heterogeneity of carbon stocks within seagrass ecosystems. Our findings indicate that carbon stocks of seagrass areas have likely been overestimated by not considering the influence of meadow landscapes, and have important relevance for the design of seagrass carbon stock assessments.

  15. Nutrient uptake by marshes and seagrasses: Ecosystem functions and spatial variability in the provision of this ecosystem servoce

    EPA Science Inventory

    Nitrogen entering coastal wetlands undergoes several important transformations involving oxidation and reduction; some ends up in the atmosphere, while much of it remains in the sediments of healthy marshes and seagrass beds – the rest passes into receiving waters. Variability i...

  16. The influence of seagrass on shell layers and Florida Bay mudbanks

    USGS Publications Warehouse

    Prager, E.J.; Halley, R.B.

    1999-01-01

    Aerial photography indicates that sometime since the early 1970's, an emergent ridge of shell debris developed on a mudbank north of Calusa Key in Florida Bay. Coarse shell deposits on and within the Bay's shallow mudbanks are believed to be the product of transport during major storm events and subsequent winnowing. However, shell material from the ridge contains nuclear bomb 14C, supporting formation within the past 30 years and the last major hurricanes to influence Florida Bay were Donna and Betsy (1960 and 1965). Results from this study suggest that the Calusa ridge and other coarse shell deposits in Florida Bay can result from, 1) periodic seagrass mortality and wave-induced transport during frequent winter cold fronts and/or 2) mollusc blooms and subsequent burial. A survey of bottom types indicates that dense to intermediate beds of seagrass, mainly Thalassia testudinum (turtle grass), occur within the shallow basins of western Florida Bay and along the margins of Bay mudbanks. Wave measurements and modeling indicate that Thalassia along mudbank margins can reduce incoming wave-energy by over 80%. Seagrass beds also host particularly dense populations of molluscs from periodic 'blooms' and are believed to be the major source of coarse sediments in the Bay. Thus, if bank-edge seagrass dies, sediments, including shell debris, become exposed and subject to greatly increased wave energy. Modeling indicates that winds typical of winter cold fronts in South Florida can produce near-bottom velocities and shear stress at a grass-free bank edge which are sufficient to transport coarse carbonate grains. Shell layers found at depth in mudbank cores can also be explained by previous episodes of sediment accretion over mollusc-rich seagrass beds or grass bed mortality at the edge of a mudbank and shell transport during cold front passage. The latter implies that mortality of marginal seagrass beds has occurred throughout the history of Florida Bay and that the

  17. Overview on seagrasses and related research in China

    NASA Astrophysics Data System (ADS)

    Shi, Yajun; Fan, Hangqing; Cui, Xiaojian; Pan, Lianghao; Li, Sen; Song, Xiukai

    2010-03-01

    Seagrass research in China is still in its infancy. Even though there has been progress recently, there is still a great deal of research needed to gain a better understanding of seagrass. In this article we review and discuss the advances in seagrass research in China from two aspects: (1) seagrass species and their distribution; (2) seagrass research in China, including studies on their taxonomy, ecology, photosynthesis, applications in aquaculture, salt-tolerance mechanisms and other research topics. A total of 18 seagrass species belonging to 8 genera are distributed in nine provinces and regions in China (including Hong Kong and Taiwan), as well as the Xisha and Nansha Archipelagos. They can be divided into two groups: a North China Group and a South China Group. Based on the seagrass distribution, the Chinese mainland coast can be divided into three sections: North China Seagrass Coast, Middle China Seagrass Coast, and South China Seagrass Coast. Ecological studies include research on seagrass communities, nutrient cycling in seagrass ecosystems, genetic diversity, pollution ecology and research in the key regions of Shandong, Guangdong, Guangxi, and Hainan. Seagrass species and their locations, community structure, ecological evaluation, epiphytes, ecological functions and threats in the key regions are also summarized. Other studies have focused on remote sensing of seagrass, threatened seagrass species of China, and pollen morphology of Halophila ovalis.

  18. Modeling future scenarios of light attenuation and potential seagrass success in a eutrophic estuary

    USGS Publications Warehouse

    del Barrio, Pilar; Ganju, Neil K.; Aretxabaleta, Alfredo L.; Hayn, Melanie; García, Andrés; Howarth, Robert W.

    2014-01-01

    Estuarine eutrophication has led to numerous ecological changes, including loss of seagrass beds. One potential cause of these losses is a reduction in light availability due to increased attenuation by phytoplankton. Future sea level rise will also tend to reduce light penetration and modify seagrass habitat. In the present study, we integrate a spectral irradiance model into a biogeochemical model coupled to the Regional Ocean Model System (ROMS). It is linked to a bio-optical seagrass model to assess potential seagrass habitat in a eutrophic estuary under future nitrate loading and sea-level rise scenarios. The model was applied to West Falmouth Harbor, a shallow estuary located on Cape Cod (Massachusetts) where nitrate from groundwater has led to eutrophication and seagrass loss in landward portions of the estuary. Measurements of chlorophyll, turbidity, light attenuation, and seagrass coverage were used to assess the model accuracy. Mean chlorophyll based on uncalibrated in-situ fluorometry varied from 28 μg L−1 at the landward-most site to 6.5 μg L−1 at the seaward site, while light attenuation ranged from 0.86 to 0.45 m-1. The model reproduced the spatial variability in chlorophyll and light attenuation with RMS errors of 3.72 μg L−1 and 0.07 m-1 respectively. Scenarios of future nitrate reduction and sea-level rise suggest an improvement in light climate in the landward basin with a 75% reduction in nitrate loading. This coupled model may be useful to assess habitat availability changes due to eutrophication and sediment resuspension and fully considers spatial variability on the tidal timescale.

  19. Seagrass meadows in a globally changing environment.

    PubMed

    Unsworth, Richard K F; van Keulen, Mike; Coles, Rob G

    2014-06-30

    Seagrass meadows are valuable ecosystem service providers that are now being lost globally at an unprecedented rate, with water quality and other localised stressors putting their future viability in doubt. It is therefore critical that we learn more about the interactions between seagrass meadows and future environmental change in the anthropocene. This needs to be with particular reference to the consequences of poor water quality on ecosystem resilience and the effects of change on trophic interactions within the food web. Understanding and predicting the response of seagrass meadows to future environmental change requires an understanding of the natural long-term drivers of change and how these are currently influenced by anthropogenic stress. Conservation management of coastal and marine ecosystems now and in the future requires increased knowledge of how seagrass meadows respond to environmental change, and how they can be managed to be resilient to these changes. Finding solutions to such issues also requires recognising people as part of the social-ecological system. This special issue aims to further enhance this knowledge by bringing together global expertise across this field. The special issues considers issues such as ecosystem service delivery of seagrass meadows, the drivers of long-term seagrass change and the socio-economic consequences of environmental change to seagrass.

  20. Seasonal variation in species composition and abundance of demersal fish and invertebrates in a Seagrass Natural Reserve on the eastern coast of the Shandong Peninsula, China

    NASA Astrophysics Data System (ADS)

    Xu, Qiang; Guo, Dong; Zhang, Peidong; Zhang, Xiumei; Li, Wentao; Wu, Zhongxin

    2016-03-01

    Seagrass habitats are structurally complex ecosystems, which support high productivity and biodiversity. In temperate systems the density of seagrass may change seasonally, and this may influence the associated fish and invertebrate community. Little is known about the role of seagrass beds as possible nursery areas for fish and invertebrates in China. To study the functioning of a seagrass habitat in northern China, demersal fish and invertebrates were collected monthly using traps, from February 2009 to January 2010. The density, leaf length and biomass of the dominant seagrass Zostera marina and water temperature were also measured. The study was conducted in a Seagrass Natural Reserve (SNR) on the eastern coast of the Shandong Peninsula, China. A total of 22 fish species and five invertebrate species were recorded over the year. The dominant fish species were Synechogobius ommaturus, Sebastes schlegelii, Pholis fangi, Pagrus major and Hexagrammos otakii and these species accounted for 87% of the total number of fish. The dominant invertebrate species were Charybdis japonica and Octopus variabilis and these accounted for 98% of the total abundance of invertebrates. There was high temporal variation in species composition and abundance. The peak number of fish species occurred in August-October 2009, while the number of individual fish and biomass was highest during November 2009. Invertebrate numbers and biomass was highest in March, April, July and September 2009. Temporal changes in species abundance of fishes and invertebrates corresponded with changes in the shoot density and leaf length of the seagrass, Zostera marina.

  1. Waste Treatment And Immobilization Plant U. S. Department Of Energy Office Of River Protection Submerged Bed Scrubber Condensate Disposition Project - Abstract # 13460

    SciTech Connect

    Yanochko, Ronald M; Corcoran, Connie

    2012-11-15

    The Hanford Waste Treatment and Immobilization Plant (WTP) will generate an off-gas treatment system secondary liquid waste stream [submerged bed scrubber (SBS) condensate], which is currently planned for recycle back to the WTP Low Activity Waste (LAW) melter. This SBS condensate waste stream is high in Tc-99, which is not efficiently captured in the vitrified glass matrix. A pre-conceptual engineering study was prepared in fiscal year 2012 to evaluate alternate flow paths for melter off-gas secondary liquid waste generated by the WTP LAW facility. This study evaluated alternatives for direct off-site disposal of this SBS without pre-treatment, which mitigates potential issues associated with recycling.

  2. Seagrass-epifauna relationships in a temperate South African estuary: Interplay between patch-size, within-patch location and algal fouling

    NASA Astrophysics Data System (ADS)

    Källén, J.; Muller, H.; Franken, M. L.; Crisp, A.; Stroh, C.; Pillay, D.; Lawrence, C.

    2012-11-01

    Understanding the primary and interactive effects of patch-size, within-patch location and degree of algal fouling on epifaunal assemblages is important for seagrass ecology and management, especially in fragmented habitats. In this paper we examine the influence of these factors on epifaunal assemblages in the Heuningnes Estuary, which is one of South Africa's oldest protected systems. Multivariate analyses indicated that all seagrass properties significantly affected epifaunal assemblages and that two gastropods viz. Assiminea globulus and Haminoea alfredensis contributed most to the dissimilarities between factors. Abundance of epifauna and A. globulus were significantly greater at the edges of seagrass beds, whereas species diversity was higher in the interior. Differences in assemblage structure between inner cores and outer edges of seagrass beds are most likely due to the physical properties of each of these zones as well as competitive interactions and habitat preferences of species that utilize each section. Epifaunal richness and A. globulus abundance were significantly greater in large beds compared to small ones and the degree of algal fouling on seagrass beds inversely affected epifaunal abundance, species richness and A. globulus abundance. Importantly, there was a strong interaction between within-patch location and patch-size, indicating that the effects of within-patch location can be altered by patch-size. When explored further, ordinations indicated that epifaunal assemblages in cores and edges became more dissimilar as bed size increased. Similarly, differences in epifaunal abundance, and diversity as well as abundance of A. globulus and H. alfredensis between cores and edges of seagrass beds became greater with increasing bed size. Our results indicate the importance of large beds in enhancing spatial heterogeneity, richness and diversity and the need for adequate protection to prevent their fragmentation in future. This is especially pertinent

  3. Automatic seagrass pattern identification on sonar images

    NASA Astrophysics Data System (ADS)

    Rahnemoonfar, Maryam; Rahman, Abdullah

    2016-05-01

    Natural and human-induced disturbances are resulting in degradation and loss of seagrass. Freshwater flooding, severe meteorological events and invasive species are among the major natural disturbances. Human-induced disturbances are mainly due to boat propeller scars in the shallow seagrass meadows and anchor scars in the deeper areas. Therefore, there is a vital need to map seagrass ecosystems in order to determine worldwide abundance and distribution. Currently there is no established method for mapping the pothole or scars in seagrass. One of the most precise sensors to map the seagrass disturbance is side scan sonar. Here we propose an automatic method which detects seagrass potholes in sonar images. Side scan sonar images are notorious for having speckle noise and uneven illumination across the image. Moreover, disturbance presents complex patterns where most segmentation techniques will fail. In this paper, by applying mathematical morphology technique and calculating the local standard deviation of the image, the images were enhanced and the pothole patterns were identified. The proposed method was applied on sonar images taken from Laguna Madre in Texas. Experimental results show the effectiveness of the proposed method.

  4. Use of a high-resolution profiling sonar and a towed video camera to map a Zostera marina bed, Solent, UK

    NASA Astrophysics Data System (ADS)

    Lefebvre, A.; Thompson, C. E. L.; Collins, K. J.; Amos, C. L.

    2009-04-01

    Seagrasses are flowering plants that develop into extensive underwater meadows and play a key role in the coastal ecosystem. In the last few years, several techniques have been developed to map and monitor seagrass beds in order to protect them. Here, we present the results of a survey using a profiling sonar, the Sediment Imager Sonar (SIS) and a towed video sledge to study a Zostera marina bed in the Solent, southern UK. The survey aimed to test the instruments for seagrass detection and to describe the area for the first time. On the acoustic data, the bed produced the strongest backscatter along a beam. A high backscatter above the bottom indicated the presence of seagrass. The results of an algorithm developed to detect seagrass from the sonar data were tested against video data. Four parameters were calculated from the SIS data: water depth, a Seagrass Index (average backscatter 10-15 cm above the bed), canopy height (height above the bed where the backscatter crosses a threshold limit) and patchiness (percentage of beams in a sweep where the backscatter 10-15 cm above the bed is greater than a threshold limit). From the video, Zostera density was estimated together with macroalgae abundance and bottom type. Patchiness calculated from the SIS data was strongly correlated to seagrass density evaluated from the video, indicating that this parameter could be used for seagrass detection. The survey area has been classified based upon seagrass density, macroalgae abundance and bottom type. Only a small area was occupied by a dense canopy whereas most of the survey area was characterised by patchy seagrass. Results indicated that Zostera marina developed only on sandy bottoms and was not found in regions of gravel. Furthermore, it was limited to a depth shallower than 1.5 m below the level of Lowest Astronomical Tide and present in small patches across the intertidal zone. The average canopy height was 15 cm and the highest density was 150 shoots m -2.

  5. Mapping seagrass and colonized hard bottom in Springs Coast, Florida using WorldView-2 satellite imagery

    NASA Astrophysics Data System (ADS)

    Baumstark, René; Duffey, Renee; Pu, Ruiliang

    2016-11-01

    The offshore extent of seagrass habitat along the West Florida (USA) coast represents an important corridor for inshore-offshore migration of economically important fish and shellfish. Surviving at the fringe of light requirements, offshore seagrass beds are sensitive to changes in water clarity. Beyond and intermingled with the offshore seagrass areas are large swaths of colonized hard bottom. These offshore habitats of the West Florida coast have lacked mapping efforts needed for status and trends monitoring. The objective of this study was to propose an object-based classification method for mapping offshore habitats and to compare results to traditional photo-interpreted maps. Benthic maps were created from WorldView-2 satellite imagery using an Object Based Image Analysis (OBIA) method and a visual photo-interpretation method. A logistic regression analysis identified depth and distance from shore as significant parameters for discriminating spectrally similar seagrass and colonized hard bottom features. Seagrass, colonized hard bottom and unconsolidated sediment (sand) were mapped with 78% overall accuracy using the OBIA method compared to 71% overall accuracy using the photo-interpretation method. This study suggests an alternative for mapping deeper, offshore habitats capable of producing higher thematic and spatial resolution maps compared to those created with the traditional photo-interpretation method.

  6. Assessing diversity and phytoremediation potential of seagrass in tropical region

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Seagrass ecosystem is one of the most important resources in the coastal areas. Seagrasses support and provide habitats for many coastal organisms in tropical region. Seagrasses are specialized marine flowering plants that have adapted to the nearshore environment with heterogeneous landscape struct...

  7. SEAGRASS DISTRIBUTION IN THE PENSACOLA BAY SYSTEM, NORTHWEST FLORIDA

    EPA Science Inventory

    Seagrass coverage in the northern Gulf of Mexico has decreased 20 to 100% in many estuaries since the 1950s. As a result, determination of seagrass coverage and identification of the cause(s) of declines are priority research issues. Aerial surveys of seagrass coverage in the P...

  8. Seagrass landscapes and their effects on associated fauna: A review

    NASA Astrophysics Data System (ADS)

    Boström, Christoffer; Jackson, Emma L.; Simenstad, Charles A.

    2006-07-01

    Seagrasses comprise some of the most heterogeneous landscape structures of shallow-water estuarine/marine ecosystems in the world. However, while knowledge at the molecular, organism, patch and community scale is pervasive, understanding of seagrass landscape ecology is more fragmentary and has not been synthesized. The growth and recruitment dynamics of seagrasses as well as man-made and/or natural disturbances create complex spatial configurations of seagrass over broad (metres to kilometres) spatial scales. Hence, it is important to identify mechanisms maintaining and/or threatening the diversity-promoting function of seagrass meadows and to understand their effects on benthic populations and communities. Although landscape ecology has recently become more integrated into seagrass research, our understanding of animal responses to variability in seagrass landscape structure is still fragmentary. By reviewing the literature to date, this paper evaluates studies on seagrass landscape ecology, testing the general null hypothesis that concepts developed in terrestrial settings can be generalized across landscapes, and (a) presenting definitions and terms used in seagrass landscape ecology, (b) reviewing geographical patterns of seagrass landscape studies to identify possible key regions and target species, (c) evaluating different methodological approaches, (d) describing the spatial and temporal scales used to describe organism responses to seagrass landscape structure, and (e) placing seagrass landscapes into an applied context.

  9. Faunal Communities Are Invariant to Fragmentation in Experimental Seagrass Landscapes

    PubMed Central

    Marion, Scott R.; Lombana, Alfonso V.; Orth, Robert J.

    2016-01-01

    Human-driven habitat fragmentation is cited as one of the most pressing threats facing many coastal ecosystems today. Many experiments have explored the consequences of fragmentation on fauna in one foundational habitat, seagrass beds, but have either surveyed along a gradient of existing patchiness, used artificial materials to mimic a natural bed, or sampled over short timescales. Here, we describe faunal responses to constructed fragmented landscapes varying from 4–400 m2 in two transplant garden experiments incorporating live eelgrass (Zostera marina L.). In experiments replicated within two subestuaries of the Chesapeake Bay, USA across multiple seasons and non-consecutive years, we comprehensively censused mesopredators and epifaunal communities using complementary quantitative methods. We found that community properties, including abundance, species richness, Simpson and functional diversity, and composition were generally unaffected by the number of patches and the size of the landscape, or the intensity of sampling. Additionally, an index of competition based on species co-occurrences revealed no trends with increasing patch size, contrary to theoretical predictions. We extend conclusions concerning the invariance of animal communities to habitat fragmentation from small-scale observational surveys and artificial experiments to experiments conducted with actual living plants and at more realistic scales. Our findings are likely a consequence of the rapid life histories and high mobility of the organisms common to eelgrass beds, and have implications for both conservation and restoration, suggesting that even small patches can rapidly promote abundant and diverse faunal communities. PMID:27244652

  10. Effectiveness and consistency of a suite of descriptors for assessing the ecological status of seagrass meadows (Posidonia oceanica L. Delile)

    NASA Astrophysics Data System (ADS)

    Rotini, Alice; Belmonte, Alessandro; Barrote, Isabel; Micheli, Carla; Peirano, Andrea; Santos, Rui O.; Silva, João; Migliore, Luciana

    2013-09-01

    The increasing rate of human-induced environmental changes on coastal marine ecosystems has created a demand for effective descriptors, in particular for those suitable for monitoring the status of seagrass meadows. Growing evidence has supported the useful application of biochemical and genetic descriptors such as secondary metabolite synthesis, photosynthetic activity and genetic diversity. In the present study, we have investigated the effectiveness of different descriptors (traditional, biochemical and genetic) in monitoring seagrass meadow conservation status. The Posidonia oceanica meadow of Monterosso al Mare (Ligurian sea, NW Mediterranean) was subjected to the measurement of bed density, leaf biometry, total phenols, soluble protein and photosynthetic pigment content as well as to RAPD marker analysis. This suite of descriptors provided evidence of their effectiveness and convenient application as markers of the conservation status of P. oceanica and/or other seagrasses. Biochemical/genetic descriptors and those obtained by traditional methods depicted a well conserved meadow with seasonal variability and, particularly in summer, indicated a healthier condition in a portion of the bed (station C), which was in agreement with the physical and sedimentological features of the station. Our results support the usefulness of introducing biochemical and genetic approaches to seagrass monitoring programs since they are effective indicators of plant physiological stress and environmental disturbance.

  11. Draft Genome Sequences of Pseudomonas moraviensis UCD-KL30, Vibrio ostreicida UCD-KL16, Colwellia sp. Strain UCD-KL20, Shewanella sp. Strain UCD-KL12, and Shewanella sp. Strain UCD-KL21, Isolated from Seagrass

    PubMed Central

    Lujan, Karley M.; Coil, David A.

    2017-01-01

    ABSTRACT Here, we present the draft genome sequences for five bacterial strains. These strains were all isolated from seagrass (Zostera marina) collected from Bodega Bay, CA, as a part of an undergraduate research project focused on seagrass-associated microbes. PMID:28360178

  12. Development of threshold values for a seagrass epiphyte ...

    EPA Pesticide Factsheets

    Epiphytes on seagrasses have been studied for more than 50 years, and proposed as an indicator of anthropogenic nutrient enrichment for over 30 years. Epiphytes have been correlated with seagrass declines, causally related to nutrient additions in both field and mesocosm experiments, and have quantifiable impacts on light available to host plants. An extensive review of seagrass epiphyte literature was conducted to determine whether seagrass epiphyte metrics can be used as a biological indicator for nutrient impacts. While a wide variety of epiphyte metrics have been used by authors, epiphyte biomass as biomass per unit seagrass biomass may be the most effective epiphyte indicator. Regression analyses of epiphyte versus seagrass response metrics were used to estimate values representing potential thresholds for environmental concern. Median epiphyte loads associated with 25 and 50% reduction in seagrass biomass, density and productivity are proposed as potential thresholds. Location-specific modifying factors (grazing pressure, seagrass species) that cause variation in response patterns are the greatest challenge to regional scale applicability of threshold values. An extensive review of seagrass epiphyte literature was conducted to determine whether, and under what conditions, seagrass epiphyte metrics could be used as a potential indicator for nutrient impacts in estuarine ecosystems. Location-specific modifying factors (grazing pressure, seagrass speci

  13. [Seagrass ecosystems: contributions to and mechanisms of carbon sequestration].

    PubMed

    Qiu, Guang-Long; Lin, Hsing-Juh; Li, Zong-Shan; Fan, Hang-Qing; Zhou, Hao-Lang; Liu, Guo-Hua

    2014-06-01

    The ocean's vegetated habitats, in particular seagrasses, mangroves and salt marshes, each capture and store a comparable amount of carbon per year, forming the Earth's blue carbon sinks, the most intense carbon sinks on the planet. Seagrass meadows, characterized by high primary productivity, efficient water column filtration and sediment stability, have a pronounced capacity for carbon sequestration. This is enhanced by low decomposition rates in anaerobic seagrass sediments. The carbon captured by seagrass meadows contributes significantly to the total blue carbon. At a global scale, seagrass ecosystems are carbon sink hot spots and have profound influences on the global carbon cycle. This importance combined with the many other functions of seagrass meadows places them among the most valuable ecosystems in the world. Unfortunately, seagrasses are declining globally at an alarming rate owing to anthropogenic disturbances and climate change, making them also among the most threatened ecosystems on the Earth. The role of coastal systems in carbon sequestration has received far too little attention and thus there are still many uncertainties in evaluating carbon sequestration of global seagrass meadows accurately. To better assess the carbon sequestration of global seagrass ecosystems, a number of scientific issues should be considered with high priorities: 1) more accurate measurements of seagrass coverage at national and global levels; 2) more comprehensive research into species- and location-specific carbon sequestration efficiencies; 3) in-depth exploration of the effects of human disturbance and global climate change on carbon capture and storage by seagrass ecosystems.

  14. The emergence of molecular profiling and omics techniques in seagrass biology; furthering our understanding of seagrasses.

    PubMed

    Davey, Peter A; Pernice, Mathieu; Sablok, Gaurav; Larkum, Anthony; Lee, Huey Tyng; Golicz, Agnieszka; Edwards, David; Dolferus, Rudy; Ralph, Peter

    2016-09-01

    Seagrass meadows are disappearing at alarming rates as a result of increasing coastal development and climate change. The emergence of omics and molecular profiling techniques in seagrass research is timely, providing a new opportunity to address such global issues. Whilst these applications have transformed terrestrial plant research, they have only emerged in seagrass research within the past decade; In this time frame we have observed a significant increase in the number of publications in this nascent field, and as of this year the first genome of a seagrass species has been sequenced. In this review, we focus on the development of omics and molecular profiling and the utilization of molecular markers in the field of seagrass biology. We highlight the advances, merits and pitfalls associated with such technology, and importantly we identify and address the knowledge gaps, which to this day prevent us from understanding seagrasses in a holistic manner. By utilizing the powers of omics and molecular profiling technologies in integrated strategies, we will gain a better understanding of how these unique plants function at the molecular level and how they respond to on-going disturbance and climate change events.

  15. Biomechanical factors contributing to self-organization in seagrass landscapes

    USGS Publications Warehouse

    Fonseca, M.S.; Koehl, M.A.R.; Kopp, B.S.

    2007-01-01

    Field observations have revealed that when water flow is consistently from one direction, seagrass shoots align in rows perpendicular to the primary axis of flow direction. In this study, live Zostera marina shoots were arranged either randomly or in rows perpendicular to the flow direction and tested in a seawater flume under unidirectional flow and waves to determine if shoot arrangement: a) influenced flow-induced force on individual shoots, b) differentially altered water flow through the canopy, and c) influenced light interception by the canopy. In addition, blade breaking strength was compared with flow-induced force to determine if changes in shoot arrangement might reduce the potential for damage to shoots. Under unidirectional flow, both current velocity in the canopy and force on shoots were significantly decreased when shoots were arranged in rows as compared to randomly. However, force on shoots was nearly constant with downstream distance, arising from the trade-off of shoot bending and in-canopy flow reduction. The coefficient of drag was higher for randomly-arranged shoots at low velocities (< 30 cm s- 1) but converged rapidly among the two shoot arrangements at higher velocities. Shoots arranged in rows tended to intercept slightly more light than those arranged randomly. Effects of shoot arrangement under waves were less clear, potentially because we did not achieve the proper plant size?row spacing ratio. At this point, we may only suggest that water motion, as opposed to light capture, is the dominant physical mechanism responsible for these shoot arrangements. Following a computation of the Environmental Stress Factor, we concluded that even photosynthetically active blades may be damaged or broken under frequently encountered storm conditions, irrespective of shoot arrangement. We hypothesize that when flow is generally from one direction, seagrass bed patterns over multiple scales of consideration may arise as a cumulative effect of

  16. MEASURING INVERTEBRATE GRAZING ON SEAGRASSES AND EPIPHYTES

    EPA Science Inventory

    The chapter describes methods to assess grazing rates, grazer preferences, and grazer impacts, by mobile organisms living in the canopy or in the rhizome layer in any seagrass system. One set of methods quantifies grazing activity in small to medium sized, mobile organisms livin...

  17. Manatees mapping seagrass (USA & Puerto Rico)

    USGS Publications Warehouse

    Slone, Daniel H.; Reid, James P.; Kenworthy, W. Judson; Di Carlo, Giuseppe; Butler, Susan M.

    2012-01-01

    West Indian manatees (Trichechus manatus) are secretive creatures. While some of their behaviours at winter aggregation sites in Florida are readily visible to the casual observer, many of their habits and movements are difficult to observe. They rely on submerged vegetation for nutrition, and seagrasses are one of their most important food sources.

  18. ACETOGENIC BACTERIA ASSOCIATED WITH SEAGRASS ROOTS

    EPA Science Inventory

    Seagrasses are adapted to being rooted in reduced, anoxic sediments with high rates of sulfate reduction. During the day, an oxygen gradient is generated around the roots, becoming anoxic at night. Thus, obligate anaerobic bacteria in the rhizosphere have to tolerate elevated oxy...

  19. Seagrass biomass and productivity in the Florida Keys, USA: ground-level and airborne measurements

    NASA Astrophysics Data System (ADS)

    Yarbro, L.; Carlson, P. R., Jr.; McHan, C.; Carlson, D. F.; Hu, C.; Danielson, T.; Durnan, B.; English, D. C.; Muller-Karger, F. E.; Yates, K. K.; Herwitz, S.; Merrill, J.; Mewes, T.

    2013-12-01

    Seagrass communities serve as essential habitat for fish and shellfish, and recent research indicates that they can play a significant role in reducing ocean acidification. As part of a collaborative project funded by the NASA ROSES program and administered by the NASA UAV Collaborative, we collected hyperspectral imagery of seagrass beds and measured productivity of Thalassia testudinum at Sugarloaf Key, Florida, in May 2012, October 2012, and May 2013. Our primary goal was to evaluate the utility of hyperspectral sensors, in general, and UAV platforms, in specific, to measure seagrass health and productivity. Airborne measurements using the AISA Eagle hyperspectral imaging system were carried out simultaneously with ground measurements of Thalassia fluorescence, oxygen metabolism, growth, and biomass, as well as remote sensing reflectance and several in situ optical properties. Water depths at the study site ranged from less than 1 m to 5 m. Phytoplankton chlorophyll-a concentrations (0.09-0.72 ug l-1), ag(440) (0-0.02 m-1), and turbidity (0.12-4.1 ntu) were relatively low for all three deployments, facilitating the collection of excellent imagery and application of water-column radiative-transfer corrections. Aboveground Thalassia and macroalgal biomass, at 18 sites in the study area, ranged from 210 to 690 and 11 to 590 gDW m-2, respectively. One-sided green leaf area index of Thalassia ranged from 0.7 to 3.0. Preliminary findings show that the sensitivity of relationships between seagrass productivity and biomass parameters and remotely-sensed habitat spectra is reduced with increasing water depth and, even in shallow water, is complicated by epiphytic algae and sediment coverage of leaf surfaces.

  20. 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.

  1. Dugong grazing and turtle cropping: grazing optimization in tropical seagrass systems?

    PubMed

    Aragones, Lemnuel V; Lawler, Ivan R; Foley, William J; Marsh, Helene

    2006-10-01

    Grazing by dugongs and cropping by green turtles have the capacity to alter the subsequent nutritional quality of seagrass regrowth. We examined the effects of simulated light and intensive grazing by dugongs and cropping by turtles on eight nutritionally relevant measures of seagrass chemical composition over two regrowth periods (short-term, 1-4 months; long-term, 11-13 months) at two seagrass communities (a mixed species community with Zostera capricorni, Halophila ovalis, Halodule uninervis, Cymodocea rotundata and C. serrulate; and a monospecific bed of Halodule uninervis) in tropical Queensland, Australia. The concentrations of organic matter, total nitrogen, total water-soluble carbohydrates, total starch, neutral detergent fiber, acid detergent fiber, acid lignin, as well as the in vitro dry matter digestibility (IVDMD) were measured in the leaves and below-ground parts of each species using near-infrared reflectance spectroscopy (NIRS). Regrowth of preferred species such as H. ovalis and H. uninervis from simulated intensive dugong grazing after a year exhibited increased (by 35 and 25%, respectively, relative to controls) whole-plant N concentrations. Similarly, regrowth of H. ovalis from simulated turtle cropping showed an increase in the leaf N concentration of 30% after a year. However, these gains are tempered by reductions in starch concentrations and increases in fiber. In the short-term, the N concentrations increased while the fiber concentrations decreased. These data provide experimental support for a grazing optimization view of herbivory in the tropical seagrass system, but with feedback in a different manner. Furthermore, we suggest that in areas where grazing is the only major source of natural disturbance, it is likely that there are potential ecosystem level effects if and when numbers of dugongs and turtles are reduced.

  2. A framework for the resilience of seagrass ecosystems.

    PubMed

    Unsworth, Richard K F; Collier, Catherine J; Waycott, Michelle; Mckenzie, Len J; Cullen-Unsworth, Leanne C

    2015-11-15

    Seagrass ecosystems represent a global marine resource that is declining across its range. To halt degradation and promote recovery over large scales, management requires a radical change in emphasis and application that seeks to enhance seagrass ecosystem resilience. In this review we examine how the resilience of seagrass ecosystems is becoming compromised by a range of local to global stressors, resulting in ecological regime shifts that undermine the long-term viability of these productive ecosystems. To examine regime shifts and the management actions that can influence this phenomenon we present a conceptual model of resilience in seagrass ecosystems. The model is founded on a series of features and modifiers that act as interacting influences upon seagrass ecosystem resilience. Improved understanding and appreciation of the factors and modifiers that govern resilience in seagrass ecosystems can be utilised to support much needed evidence based management of a vital natural resource.

  3. Rapidly spreading seagrass invades the Caribbean with unknown ecological consequences

    USGS Publications Warehouse

    Rogers, Caroline S.; Willette, Demian A; Miller, Jeff

    2014-01-01

    The non-native seagrass Halophila stipulacea has spread rapidly throughout the Caribbean Sea (Willette et al. 2014); without additional research, the ecological ramifications of this invasion are difficult to predict. Biodiversity, connectivity of marine ecosystems, and recovery of degraded coral reefs could all be affected. The invasive seagrass, native to the Red Sea and Indian Ocean, has taken over sand bottoms and intermixed with or replaced native seagrasses, including Thalassia testudinum, Syringodium filiforme, and Halodule wrightii.

  4. Seagrasses in northern Gulf of Mexico: An ecosystem in trouble

    USGS Publications Warehouse

    ,

    2000-01-01

    The USGS National Wetlands Research Center has documented that Seagrasses in the northern Gulf of Mexico constitute an ecosystem in trouble. From studies in St. Andrews Bay, Period Bay, the Chandeleur Islands, and the Gulf Islands National Seashore, scientists have discovered that declining seagrass acreage ranges from 12% to 66% in bays and estuaries of the Gulf of Mexico. Not only are seagrasses disappearing, but they are also changing in species composition, densities, and patchiness.

  5. Seagrass restoration enhances "blue carbon" sequestration in coastal waters.

    PubMed

    Greiner, Jill T; McGlathery, Karen J; Gunnell, John; McKee, Brent A

    2013-01-01

    Seagrass meadows are highly productive habitats that provide important ecosystem services in the coastal zone, including carbon and nutrient sequestration. Organic carbon in seagrass sediment, known as "blue carbon," accumulates from both in situ production and sedimentation of particulate carbon from the water column. Using a large-scale restoration (>1700 ha) in the Virginia coastal bays as a model system, we evaluated the role of seagrass, Zosteramarina, restoration in carbon storage in sediments of shallow coastal ecosystems. Sediments of replicate seagrass meadows representing different age treatments (as time since seeding: 0, 4, and 10 years), were analyzed for % carbon, % nitrogen, bulk density, organic matter content, and ²¹⁰Pb for dating at 1-cm increments to a depth of 10 cm. Sediment nutrient and organic content, and carbon accumulation rates were higher in 10-year seagrass meadows relative to 4-year and bare sediment. These differences were consistent with higher shoot density in the older meadow. Carbon accumulation rates determined for the 10-year restored seagrass meadows were 36.68 g C m⁻² yr⁻¹. Within 12 years of seeding, the restored seagrass meadows are expected to accumulate carbon at a rate that is comparable to measured ranges in natural seagrass meadows. This the first study to provide evidence of the potential of seagrass habitat restoration to enhance carbon sequestration in the coastal zone.

  6. [Benthic fauna associated to a Thalassia testudinum (Hydrocharitaceae) bed in Parque Nacional Morrocoy, Venezuela].

    PubMed

    Rodríguez, C; Villamizar, E

    2000-12-01

    The benthic fauna and diel variation in a shallow seagrass bed (Thalassia testudinum) were studied in Playa Mero, Venezuela. Samples of organisms and sediments were taken using PVC cylinders, 5cm in diameter, along a transect perpendicular to the coast. Seagrass cover, shoot density and biomass were estimated. The seagrass cover was homogeneous along the transect. The intermediate zone had the highest number of shoots and of above-ground and rhizome biomass. Composition and abundance of benthic organisms were related with seagrass and sediment characteristics. Sediment organic matter content and organism abundance were highest near the shore Molluscs, polychaetes, oligochaetes and nematodes were the most abundant groups. Species richness was higher in daytime (40 versus 28 at night). Gastropods were the most abundant organisms both at day and night while polychaetes and crustaceans increased during the day, and holoturids were more numerous at night.

  7. Tropical seaweed beds are important habitats for mobile invertebrate epifauna

    NASA Astrophysics Data System (ADS)

    Tano, Stina; Eggertsen, M.; Wikström, S. A.; Berkström, C.; Buriyo, A. S.; Halling, C.

    2016-12-01

    Marine macrophyte habitats in temperate regions provide productive habitats for numerous organisms, with their abundant and diverse invertebrate epifaunal assemblages constituting important linkages between benthic primary production and higher trophic levels. While it is commonly also recognized that certain vegetated habitats in the tropics, such as seagrass meadows, can harbour diverse epifaunal assemblages and may constitute important feeding grounds to fish, little is known about the epifaunal assemblages associated with tropical seaweed beds. We investigated the abundance, biomass and taxon richness of the mobile epifaunal community (≥1 mm) of tropical East African seaweed beds, as well as the abundance of invertivorous fishes, and compared it with that of closely situated seagrass meadows, to establish the ecological role of seaweed beds as habitat for epifauna as well as potential feeding grounds for fish. The results showed that seaweed beds had a higher abundance of mobile epifauna (mean ± SD: 10,600 ± 6000 vs 3700 ± 2800 per m2) than seagrass meadows, as well as a higher invertebrate biomass (35.9 ± 46.8 vs 1.9 ± 2.1 g per m2) and taxon richness (32.7 ± 11.8 vs 19.1 ± 6.3 taxa per sample), despite having a lower macrophyte biomass. Additionally, the high abundance of invertivorous fishes found in seaweed beds indicates that they act as important feeding grounds to several fish species in the region.

  8. Epiphyte presence and seagrass species identity influence rates of herbivory in Mediterranean seagrass meadows

    NASA Astrophysics Data System (ADS)

    Marco-Méndez, Candela; Ferrero-Vicente, Luis Miguel; Prado, Patricia; Heck, Kenneth L.; Cebrián, Just; Sánchez-Lizaso, Jose Luis

    2015-03-01

    Herbivory on Mediterranean seagrass species is generally low compared to consumption of some other temperate and tropical species of seagrasses. In this study we: (1) investigate the feeding preference of the two dominant Mediterranean seagrass herbivores, the sea urchin Paracentrotus lividus and the fish Sarpa salpa, on Posidonia oceanica and Cymodocea nodosa and (2) elucidate the role of epiphytes in herbivore choices. We assessed consumption rates by tethering seagrass shoots, and preferences by food choice experiments with the following paired combinations: 1) Epiphytized leaves of both C. nodosa vs. P. oceanica (CE vs PE); 2) Non-epiphytized leaves of C. nodosa vs. P. oceanica (CNE vs. PNE); 3) Epiphytized vs non-epiphytized leaves of C. nodosa (CE vs. CNE) and 4) Epiphytized vs non-epiphytized leaves of P. oceanica (PE vs PNE). We found that preference for C. nodosa was weak for S. salpa, but strong for P. lividus, the species responsible for most consumption at our study. Overall both herbivores showed preference for epiphytized leaves. The higher nutritional quality of C. nodosa leaves and epiphytes together with the high coverage and diversity of the epiphyte community found on its leaves help explain the higher levels of herbivory recorded on epiphyted leaves of C. nodosa. Other factors such as seagrass accessibility, herbivore mobility and size, and behavioral responses to predation risks, may also affect the intensity of seagrass herbivory, and studies addressing the interactions with these factors are needed to improve our understanding of the nature, extent and implications of herbivory in coastal ecosystems.

  9. Bed Bugs

    EPA Pesticide Factsheets

    Prevent, identify, and treat bed bug infestations using EPA’s step-by-step guides, based on IPM principles. Find pesticides approved for bed bug control, check out the information clearinghouse, and dispel bed bug myths.

  10. Research Abstracts.

    ERIC Educational Resources Information Center

    Plotnick, Eric

    2001-01-01

    Presents research abstracts from the ERIC Clearinghouse on Information and Technology. Topics include: classroom communication apprehension and distance education; outcomes of a distance-delivered science course; the NASA/Kennedy Space Center Virtual Science Mentor program; survey of traditional and distance learning higher education members;…

  11. Research Abstracts.

    ERIC Educational Resources Information Center

    Plotnik, Eric

    2001-01-01

    Presents six research abstracts from the ERIC (Educational Resources Information Center) database. Topics include: effectiveness of distance versus traditional on-campus education; improved attribution recall from diversification of environmental context during computer-based instruction; qualitative analysis of situated Web-based learning;…

  12. Abstract Constructions.

    ERIC Educational Resources Information Center

    Pietropola, Anne

    1998-01-01

    Describes a lesson designed to culminate a year of eighth-grade art classes in which students explore elements of design and space by creating 3-D abstract constructions. Outlines the process of using foam board and markers to create various shapes and optical effects. (DSK)

  13. Draft Genome Sequence of Marinobacter hydrocarbonoclasticus Strain STW2, a Polycyclic Aromatic Hydrocarbon-Degrading and Denitrifying Bacterium from the Rhizosphere of Seagrass Enhalus acodoides

    PubMed Central

    Ling, Juan; Lin, Liyun; Zhang, Yanying; Lin, Xiancheng; Ahamad, Manzoor; Zhou, Weiguo

    2017-01-01

    ABSTRACT Here, we report the draft genome sequence of Marinobacter hydrocarbonoclasticus strain STW2, which was isolated from the rhizosphere of seagrass Enhalus acodoides. This study will facilitate future studies on the genetic pathways of marine microbes capable of both polycyclic aromatic hydrocarbon degradation and nitrate reduction. PMID:28232431

  14. Seagrass epiphytes: useful indicator, potential biological criterion, or forlorn hope?

    EPA Science Inventory

    Epiphytes on seagrasses have been studied for more than 50 years, and proposed as an indicator of anthropogenic nutrient enrichment for over 30 years. Epiphytes have been correlated with seagrass declines, causally related to nutrient additions in both field and mesocosm experim...

  15. Effects of bioturbation on seagrasses: Implications for management and restoration

    EPA Science Inventory

    Marine and estuarine fauna can diminish or enhance seagrass condition simply as a result of their burrowing, excavating, re-working, and feeding activities (e.g., bioturbation). We present the first comprehensive review of the effects of bioturbators on seagrasses and associated ...

  16. Photosynthethic carbon reduction by seagrasses exposed to ultraviolet B radiation

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The species of seagrasses were selected on the basis of their dominance in the marine system, contribution to total productivity, and importance to the life histories of organisms in the Indian River lagoon system along the central Florida east coast. The three seagrasses were Halophilia engelmannii, Halodule wrightii, and Syringodium filiforme. These seagrasses form an excellent experimental system as their areas of dominance fall more or less along a natural gradient of UV-B and photosynthetically active radiation (PAR) penetration. The sensitivity of photosynthesis in the seagrasses was determined and their photosynthetic response to levels of UV-B simulating atmospheric ozone depletion was monitored. Further experiments explore the possible attenuation or repair of UV-B induced photosynthetic inhibition by PAR, the role of epiphytic growth upon seagrasses as a protective UV-B shield, and the inhibition of photosynthesis in response to UV-A is studied.

  17. A comparison of the impact of 'seagrass-friendly' boat mooring systems on Posidonia australis.

    PubMed

    Demers, Marie-Claire A; Davis, Andrew R; Knott, Nathan A

    2013-02-01

    Permanent boat moorings have contributed to the decline of seagrasses worldwide, prompting the development of 'seagrass-friendly' moorings. We contrasted seagrass cover and density (predominantly Posidonia australis) in the vicinity of three mooring types and nearby reference areas lacking moorings in Jervis Bay, Australia. We examined two types of 'seagrass-friendly' mooring and a conventional 'swing' mooring. 'Swing' moorings produced significant seagrass scour, denuding patches of ~9 m radius. Seagrass-friendly 'cyclone' moorings produced extensive denuded patches (average radius of ~18 m). Seagrass-friendly 'screw' moorings, conversely, had similar seagrass cover to nearby reference areas. Our findings reinforce previous work highlighting the negative effects of 'swing' and 'cyclone' moorings. In contrast, the previously unstudied 'screw' moorings were highly effective. We conclude that regular maintenance of moorings and the monitoring of surrounding seagrass are required to ensure that 'seagrass-friendly' moorings are operating effectively. This is important, as following damage Posidonia will take many decades to recover.

  18. CARBON AND NITROGEN ALLOCATION MODEL FOR THE SUB-TROPICAL SEAGRASS THALASSIA TESTUDINUM AND THE TEMPERATE SEAGRASS ZOSTER MARINA

    EPA Science Inventory

    Our understanding of seagrass physiology is based on crude estimates of production and biomass. To better understand the complex physiological relationships between the plants and the environment we developed a model of carbon and nitrogen allocation in the sub-tropical seagrass ...

  19. Bed bugs.

    PubMed

    Foulke, Galen T; Anderson, Bryan E

    2014-09-01

    The term bed bug is applied to 2 species of genus Cimex: lectularius describes the common or temperate bed bug, and hemipterus its tropical cousin. Cimex lectularius is aptly named; its genus and species derive from the Latin words for bug and bed, respectively. Though the tiny pest is receiving increased public attention and scrutiny, the bed bug is hardly a new problem.

  20. CARBON BUDGET FOR A SUB-TROPICAL SEAGRASS DOMINATED COASTAL LAGOON: HOW IMPORTANT ARE SEAGRASSES TO TOTAL ECOSYSTEM NET PRIMARY PRODUCTION?

    EPA Science Inventory

    Seagrasses dominate macrophyte biomass in many estuaries. Historically, it has been assumed that because of the large standing stock seagrasses also dominate primary production. We tested this assumption by developing 3 carbon budgets to examine the contribution of autotrophic ...

  1. Accelerating loss of seagrasses across the globe threatens coastal ecosystems

    PubMed Central

    Waycott, Michelle; Duarte, Carlos M.; Carruthers, Tim J. B.; Orth, Robert J.; Dennison, William C.; Olyarnik, Suzanne; Calladine, Ainsley; Fourqurean, James W.; Heck, Kenneth L.; Hughes, A. Randall; Kendrick, Gary A.; Kenworthy, W. Judson; Short, Frederick T.; Williams, Susan L.

    2009-01-01

    Coastal ecosystems and the services they provide are adversely affected by a wide variety of human activities. In particular, seagrass meadows are negatively affected by impacts accruing from the billion or more people who live within 50 km of them. Seagrass meadows provide important ecosystem services, including an estimated $1.9 trillion per year in the form of nutrient cycling; an order of magnitude enhancement of coral reef fish productivity; a habitat for thousands of fish, bird, and invertebrate species; and a major food source for endangered dugong, manatee, and green turtle. Although individual impacts from coastal development, degraded water quality, and climate change have been documented, there has been no quantitative global assessment of seagrass loss until now. Our comprehensive global assessment of 215 studies found that seagrasses have been disappearing at a rate of 110 km2 yr−1 since 1980 and that 29% of the known areal extent has disappeared since seagrass areas were initially recorded in 1879. Furthermore, rates of decline have accelerated from a median of 0.9% yr−1 before 1940 to 7% yr−1 since 1990. Seagrass loss rates are comparable to those reported for mangroves, coral reefs, and tropical rainforests and place seagrass meadows among the most threatened ecosystems on earth. PMID:19587236

  2. Seagrass ecosystems as a globally significant carbon stock

    NASA Astrophysics Data System (ADS)

    Fourqurean, James W.; Duarte, Carlos M.; Kennedy, Hilary; Marbà, Núria; Holmer, Marianne; Mateo, Miguel Angel; Apostolaki, Eugenia T.; Kendrick, Gary A.; Krause-Jensen, Dorte; McGlathery, Karen J.; Serrano, Oscar

    2012-07-01

    The protection of organic carbon stored in forests is considered as an important method for mitigating climate change. Like terrestrial ecosystems, coastal ecosystems store large amounts of carbon, and there are initiatives to protect these `blue carbon' stores. Organic carbon stocks in tidal salt marshes and mangroves have been estimated, but uncertainties in the stores of seagrass meadows--some of the most productive ecosystems on Earth--hinder the application of marine carbon conservation schemes. Here, we compile published and unpublished measurements of the organic carbon content of living seagrass biomass and underlying soils in 946 distinct seagrass meadows across the globe. Using only data from sites for which full inventories exist, we estimate that, globally, seagrass ecosystems could store as much as 19.9Pg organic carbon; according to a more conservative approach, in which we incorporate more data from surface soils and depth-dependent declines in soil carbon stocks, we estimate that the seagrass carbon pool lies between 4.2 and 8.4Pg carbon. We estimate that present rates of seagrass loss could result in the release of up to 299Tg carbon per year, assuming that all of the organic carbon in seagrass biomass and the top metre of soils is remineralized.

  3. 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

  4. 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 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/Fm′), 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

  5. Recovery of a top predator mediates negative eutrophic effects on seagrass

    USGS Publications Warehouse

    Hughes, Brent B.; Eby, Ron; Van Dyke, Eric; Tinker, M. Tim; Marks, Corina I.; Johnson, Kenneth S.; Wasson, Kerstin

    2013-01-01

    A fundamental goal of the study of ecology is to determine the drivers of habitat-forming vegetation, with much emphasis given to the relative importance to vegetation of “bottom-up” forces such as the role of nutrients and “top-down” forces such as the influence of herbivores and their predators. For coastal vegetation (e.g., kelp, seagrass, marsh, and mangroves) it has been well demonstrated that alterations to bottom-up forcing can cause major disturbances leading to loss of dominant vegetation. One such process is anthropogenic nutrient loading, which can lead to major changes in the abundance and species composition of primary producers, ultimately affecting important ecosystem services. In contrast, much less is known about the relative importance of apex predators on coastal vegetated ecosystems because most top predator populations have been depleted or lost completely. Here we provide evidence that an unusual four-level trophic cascade applies in one such system, whereby a top predator mitigates the bottom-up influences of nutrient loading. In a study of seagrass beds in an estuarine ecosystem exposed to extreme nutrient loading, we use a combination of a 50-y time series analysis, spatial comparisons, and mesocosm and field experiments to demonstrate that sea otters (Enhydra lutris) promote the growth and expansion of eelgrass (Zostera marina) through a trophic cascade, counteracting the negative effects of agriculturally induced nutrient loading. Our results add to a small but growing body of literature illustrating that significant interactions between bottom-up and top-down forces occur, in this case with consequences for the conservation of valued ecosystem services provided by seagrass.

  6. Recovery of a top predator mediates negative eutrophic effects on seagrass

    PubMed Central

    Hughes, Brent B.; Eby, Ron; Van Dyke, Eric; Tinker, M. Tim; Marks, Corina I.; Johnson, Kenneth S.; Wasson, Kerstin

    2013-01-01

    A fundamental goal of the study of ecology is to determine the drivers of habitat-forming vegetation, with much emphasis given to the relative importance to vegetation of “bottom-up” forces such as the role of nutrients and “top-down” forces such as the influence of herbivores and their predators. For coastal vegetation (e.g., kelp, seagrass, marsh, and mangroves) it has been well demonstrated that alterations to bottom-up forcing can cause major disturbances leading to loss of dominant vegetation. One such process is anthropogenic nutrient loading, which can lead to major changes in the abundance and species composition of primary producers, ultimately affecting important ecosystem services. In contrast, much less is known about the relative importance of apex predators on coastal vegetated ecosystems because most top predator populations have been depleted or lost completely. Here we provide evidence that an unusual four-level trophic cascade applies in one such system, whereby a top predator mitigates the bottom-up influences of nutrient loading. In a study of seagrass beds in an estuarine ecosystem exposed to extreme nutrient loading, we use a combination of a 50-y time series analysis, spatial comparisons, and mesocosm and field experiments to demonstrate that sea otters (Enhydra lutris) promote the growth and expansion of eelgrass (Zostera marina) through a trophic cascade, counteracting the negative effects of agriculturally induced nutrient loading. Our results add to a small but growing body of literature illustrating that significant interactions between bottom-up and top-down forces occur, in this case with consequences for the conservation of valued ecosystem services provided by seagrass. PMID:23983266

  7. Geospatial interface and model for predicting potential seagrass habitat

    EPA Science Inventory

    Restoration of ecosystem services provided by seagrass habitats in estuaries requires a clear understanding of the modes of action of multiple interacting stressors including nutrients, climate change, coastal land-use change, and habitat modification. We have developed a geos...

  8. MAPPING BURROWING SHRIMP AND SEAGRASS IN YAQUINA ESTUARY

    EPA Science Inventory

    Burrowing shrimp and seagrasses create extensive intertidal and shallow subtidal habitats within Pacific NW estuaries. Maps of their populations are useful to inform estuarine managers of locations that deserve special consideration for conservation, and to inform oyster farmers...

  9. Nonnutrient Anthropogenic Chemicals in Seagrass Ecosystems: Fate and Effects

    EPA Science Inventory

    Literature reviews have been published for seagrass taxonomy, geographical distribution, species diversity, grazer-epiphyte interactions, morphology, physiology, salinity requirements, and nutrient impacts (Schaffer 1995; Jernakoff et al. 1996; Touchette and Burholder 2000; Borto...

  10. The effects of water parameters on monthly seagrass percentage cover in Lawas, East Malaysia.

    PubMed

    Ahmad-Kamil, E I; Ramli, R; Jaaman, S A; Bali, J; Al-Obaidi, J R

    2013-01-01

    Seagrass is a valuable marine ecosystem engineer. However, seagrass population is declining worldwide. The lack of seagrass research in Malaysia raises questions about the status of seagrasses in the country. The seagrasses in Lawas, which is part of the coral-mangrove-seagrass complex, have never been studied in detail. In this study, we examine whether monthly changes of seagrass population in Lawas occurred. Data on estimates of seagrass percentage cover and water physicochemical parameters (pH, turbidity, salinity, temperature, and dissolved oxygen) were measured at 84 sampling stations established within the study area from June 2009 to May 2010. Meteorological data such as total rainfall, air temperature, and Southern Oscillation Index were also investigated. Our results showed that (i) the monthly changes of seagrass percentage cover are significant, (ii) the changes correlated significantly with turbidity measurements, and (iii) weather changes affected the seagrass populations. Our study indicates seagrass percentage increased during the El-Nino period. These results suggest that natural disturbances such as weather changes affect seagrass populations. Evaluation of land usage and measurements of other water physicochemical parameters (such as heavy metal, pesticides, and nutrients) should be considered to assess the health of seagrass ecosystem at the study area.

  11. Seagrasses in tropical Australia, productive and abundant for decades decimated overnight.

    PubMed

    Pollard, Peter C; Greenway, Margaret

    2013-03-01

    Seagrass ecosystems provide unique coastal habitats critical to the life cycle of many species. Seagrasses are a major store of organic carbon. While seagrasses are globally threatened and in decline, in Cairns Harbour, Queensland, on the tropical east coast of Australia, they have flourished. We assessed seagrass distribution in Cairns Harbour between 1953 and 2012 from historical aerial photographs, Google map satellite images, existing reports and our own surveys of their distribution. Seasonal seagrass physiology was assessed through gross primary production, respiration and photosynthetic characteristics of three seagrass species, Cymodocea serrulata, Thalassia hemprichii and Zostera muelleri. At the higher water temperatures of summer, respiration rates increased in all three species, as did their maximum rates of photosynthesis. All three seagrasses achieved maximum rates of photosynthesis at low tide and when they were exposed. For nearly six decades there was little change in seagrass distribution in Cairns Harbour. This was most likely because the seagrasses were able to achieve sufficient light for growth during intertidal and low tide periods. With historical data of seagrass distribution and measures of species production and respiration, could seagrass survival in a changing climate be predicted? Based on physiology, our results predicted the continued maintenance of the Cairns Harbour seagrasses, although one species was more susceptible to thermal disturbance. However, in 2011 an unforeseen episodic disturbance - Tropical Cyclone Yasi - and associated floods lead to the complete and catastrophic loss of all the seagrasses in Cairns Harbour.

  12. The Effects of Water Parameters on Monthly Seagrass Percentage Cover in Lawas, East Malaysia

    PubMed Central

    Ahmad-Kamil, E. I.; Ramli, R.; Jaaman, S. A.; Bali, J.; Al-Obaidi, J. R.

    2013-01-01

    Seagrass is a valuable marine ecosystem engineer. However, seagrass population is declining worldwide. The lack of seagrass research in Malaysia raises questions about the status of seagrasses in the country. The seagrasses in Lawas, which is part of the coral-mangrove-seagrass complex, have never been studied in detail. In this study, we examine whether monthly changes of seagrass population in Lawas occurred. Data on estimates of seagrass percentage cover and water physicochemical parameters (pH, turbidity, salinity, temperature, and dissolved oxygen) were measured at 84 sampling stations established within the study area from June 2009 to May 2010. Meteorological data such as total rainfall, air temperature, and Southern Oscillation Index were also investigated. Our results showed that (i) the monthly changes of seagrass percentage cover are significant, (ii) the changes correlated significantly with turbidity measurements, and (iii) weather changes affected the seagrass populations. Our study indicates seagrass percentage increased during the El-Nino period. These results suggest that natural disturbances such as weather changes affect seagrass populations. Evaluation of land usage and measurements of other water physicochemical parameters (such as heavy metal, pesticides, and nutrients) should be considered to assess the health of seagrass ecosystem at the study area. PMID:24163635

  13. Suitability of seagrasses and submerged aquatic vegetation as indicators of eutrophication

    EPA Science Inventory

    Rooted submerged aquatic vegetation (SAV) encompasses a large diversity of species that range from obligate halophytes such as, seagrasses, to euryhaline species and freshwater obligates. All seagrass and SAV provide key biological functions within the enclosed bays, estuaries, a...

  14. PRODUCTION OF PLANT GROWTH PROMOTING SUBSTANCES IN BACTERIAL ISOLATES FROM THE SEAGRASS RHIZOSPHERE

    EPA Science Inventory

    Plants and rhizosphere bacteria have evolved chemical signals that enable their mutual growth. These relationships have been well investigated with agriculturally important plants, but not in seagrasses, which are important to the stability of estuaries. Seagrasses are rooted in ...

  15. Specificity in Mesograzer-Induced Defences in Seagrasses

    PubMed Central

    Martínez-Crego, Begoña; Arteaga, Pedro; Ueber, Alexandra; Engelen, Aschwin H.; Santos, Rui; Molis, Markus

    2015-01-01

    Grazing-induced plant defences that reduce palatability to herbivores are widespread in terrestrial plants and seaweeds, but they have not yet been reported in seagrasses. We investigated the ability of two seagrass species to induce defences in response to direct grazing by three associated mesograzers. Specifically, we conducted feeding-assayed induction experiments to examine how mesograzer-specific grazing impact affects seagrass induction of defences within the context of the optimal defence theory. We found that the amphipod Gammarus insensibilis and the isopod Idotea chelipes exerted a low-intensity grazing on older blades of the seagrass Cymodocea nodosa, which reflects a weak grazing impact that may explain the lack of inducible defences. The isopod Synischia hectica exerted the strongest grazing impact on C. nodosa via high-intensity feeding on young blades with a higher fitness value. This isopod grazing induced defences in C. nodosa as indicated by a consistently lower consumption of blades previously grazed for 5, 12 and 16 days. The lower consumption was maintained when offered tissues with no plant structure (agar-reconstituted food), but showing a reduced size of the previous grazing effect. This indicates that structural traits act in combination with chemical traits to reduce seagrass palatability to the isopod. Increase in total phenolics but not in C:N ratio and total nitrogen of grazed C. nodosa suggests chemical defences rather than a modified nutritional quality as primarily induced chemical traits. We detected no induction of defences in Zostera noltei, which showed the ability to replace moderate losses of young biomass to mesograzers via compensatory growth. Our study provides the first experimental evidence of induction of defences against meso-herbivory that reduce further consumption in seagrasses. It also emphasizes the relevance of grazer identity in determining the level of grazing impact triggering resistance and compensatory

  16. Seagrass meadows as a globally significant carbonate reservoir

    NASA Astrophysics Data System (ADS)

    Mazarrasa, I.; Marbà, N.; Lovelock, C. E.; Serrano, O.; Lavery, P. S.; Fourqurean, J. W.; Kennedy, H.; Mateo, M. A.; Krause-Jensen, D.; Steven, A. D. L.; Duarte, C. M.

    2015-03-01

    There has been a growing interest in quantifying the capacity of seagrass ecosystems to act as carbon sinks as a natural way of offsetting anthropogenic carbon emissions to the atmosphere. However, most of the efforts have focused on the organic carbon (POC) stocks and accumulation rates and ignored the inorganic carbon (PIC) fraction, despite important carbonate pools associated with calcifying organisms inhabiting the meadows, such as epiphytes and benthic invertebrates, and despite the relevance that carbonate precipitation and dissolution processes have in the global carbon cycle. This study offers the first assessment of the global PIC stocks in seagrass sediments using a synthesis of published and unpublished data on sediment carbonate concentration from 402 vegetated and 34 adjacent un-vegetated sites. PIC stocks in the top 1 m sediments ranged between 3 and 1660 Mg PIC ha-1, with an average of 654 ± 24 Mg PIC ha-1, exceeding about 5 fold those of POC reported in previous studies. Sedimentary carbonate stocks varied across seagrass communities, with meadows dominated by Halodule, Thalassia or Cymodocea supporting the highest PIC stocks, and tended to decrease polewards at a rate of -8 ± 2 Mg PIC ha-1 degree-1 of latitude (GLM, p < 0.0003). Using PIC concentration and estimates of sediment accretion in seagrass meadows, mean PIC accumulation rates in seagrass sediments is 126.3 ± 0.7 g PIC m-2 y-1. Based on the global extent of seagrass meadows (177 000 to 600 000 km2), these ecosystems globally store between 11 and 39 Pg of PIC in the top meter of sediment and accumulate between 22 and 76 Tg PIC y-1, representing a significant contribution to the carbonate dynamics of coastal areas. Despite that these high rates of carbonate accumulation imply CO2 emissions from precipitation, seagrass meadows are still strong CO2 sinks as demonstrates the comparison of carbon (POC and POC) stocks between vegetated and adjacent un-vegetated sediments.

  17. Impact of mooring activities on carbon stocks in seagrass meadows

    NASA Astrophysics Data System (ADS)

    Serrano, O.; Ruhon, R.; Lavery, P. S.; Kendrick, G. A.; Hickey, S.; Masqué, P.; Arias-Ortiz, A.; Steven, A.; Duarte, C. M.

    2016-03-01

    Boating activities are one of the causes that threaten seagrass meadows and the ecosystem services they provide. Mechanical destruction of seagrass habitats may also trigger the erosion of sedimentary organic carbon (Corg) stocks, which may contribute to increasing atmospheric CO2. This study presents the first estimates of loss of Corg stocks in seagrass meadows due to mooring activities in Rottnest Island, Western Australia. Sediment cores were sampled from seagrass meadows and from bare but previously vegetated sediments underneath moorings. The Corg stores have been compromised by the mooring deployment from 1930s onwards, which involved both the erosion of existing sedimentary Corg stores and the lack of further accumulation of Corg. On average, undisturbed meadows had accumulated ~6.4 Kg Corg m-2 in the upper 50 cm-thick deposits at a rate of 34 g Corg m-2 yr-1. The comparison of Corg stores between meadows and mooring scars allows us to estimate a loss of 4.8 kg Corg m-2 in the 50 cm-thick deposits accumulated over ca. 200 yr as a result of mooring deployments. These results provide key data for the implementation of Corg storage credit offset policies to avoid the conversion of seagrass ecosystems and contribute to their preservation.

  18. Impact of mooring activities on carbon stocks in seagrass meadows

    PubMed Central

    Serrano, O.; Ruhon, R.; Lavery, P. S.; Kendrick, G. A.; Hickey, S.; Masqué, P.; Arias-Ortiz, A.; Steven, A.; Duarte, C. M.

    2016-01-01

    Boating activities are one of the causes that threaten seagrass meadows and the ecosystem services they provide. Mechanical destruction of seagrass habitats may also trigger the erosion of sedimentary organic carbon (Corg) stocks, which may contribute to increasing atmospheric CO2. This study presents the first estimates of loss of Corg stocks in seagrass meadows due to mooring activities in Rottnest Island, Western Australia. Sediment cores were sampled from seagrass meadows and from bare but previously vegetated sediments underneath moorings. The Corg stores have been compromised by the mooring deployment from 1930s onwards, which involved both the erosion of existing sedimentary Corg stores and the lack of further accumulation of Corg. On average, undisturbed meadows had accumulated ~6.4 Kg Corg m−2 in the upper 50 cm-thick deposits at a rate of 34 g Corg m−2 yr−1. The comparison of Corg stores between meadows and mooring scars allows us to estimate a loss of 4.8 kg Corg m−2 in the 50 cm-thick deposits accumulated over ca. 200 yr as a result of mooring deployments. These results provide key data for the implementation of Corg storage credit offset policies to avoid the conversion of seagrass ecosystems and contribute to their preservation. PMID:26979407

  19. Seagrass species distribution, density and coverage at Panggang Island, Jakarta

    NASA Astrophysics Data System (ADS)

    Wahab, Iswandi; Madduppa, Hawis; Kawaroe, Mujizat

    2017-01-01

    This study aimed to assess species distribution, density and coverage of seagrass in Panggang Island, within Kepulauan Seribu Marine National Park, northern Jakarta. Seagrass sampling was conducted between March to April 2016 at three observation stations in the West, East, and South of Panggang Island. A total of 6 seagrass species was recorded during sampling period, including Cymodocea rotundata, C. serulata, Halodule uninervis, Syiringodium isoetifolium, Enhalus acoroides, and Thalassia hempricii. All species were observed in the South station, while in the West and East station found only three species (C. rotundata, E. acoroides, and T. hemprichii). While, C. rotundata and T. hemprichii were observed at all station. The highest density was observed for C. rotundata (520 ind/m2) and for T. hempricii (619 ind/m2) in the West station and South Station, respectively. The lowest density was observed in South Station for C. serulata (18 ind/m2), Halodule uninervis (20 ind/m2), and Syiringodium isoetifolium (15 ind/m2). Seagrass coverage of Thalassia hempricii was the highest (43.60%) and the lowest observed at Syiringodium isoetifolium (0.40%). This could be basic information for the management of seagrass ecosystem in the Kepulauan Seribu Marine National Park.

  20. Seagrass as the main food source of Neaxius acanthus (Thalassinidea: Strahlaxiidae), its burrow associates, and of Corallianassa coutierei (Thalassinidea: Callianassidae)

    NASA Astrophysics Data System (ADS)

    Kneer, Dominik; Asmus, Harald; Vonk, Jan Arie

    2008-09-01

    Burrows of the thalassinidean shrimps Neaxius acanthus and Corallianassa coutierei are striking aspects in tropical seagrass beds of the Spermonde Archipelago, Indonesia. Burrow construction, behaviour, burrow type and associated commensal community were investigated to clarify the ecological role and food requirements of these shrimps and their commensals. Gut content analysis and stable-isotope data were used to unravel the food sources and the trophic interactions among the commensal community. Individuals of Neaxius acanthus were caught on Bone Batang Island. In narrow aquaria filled with sediment they constructed burrows resembling those found in the field. During burrow construction and maintenance only little sediment was brought to the surface, most was sorted and compacted to create a distinct lining. Maintenance work by single shrimps typically took about 5 min, after which the shrimp walked up to the entrance and rested for a similar period of time. There were no differences in behaviour between day and night. Intrasexual encounters inside the burrow were characterised by a high level of aggression and all resulted in one participant being driven out of the burrow. Intersexual encounters led to coexistence with both animals taking turns in burrow maintenance and guarding the entrance. Offered seagrass leaves were pulled underground, cut into pieces and eventually integrated into the lining. Burrows of Corallianassa coutierei resembled a deep U-shape. Chambers branching off halfway down and at the deepest point contained seagrass fragments. All steep parts of the burrow were lined similar to burrows of N. acanthus. No commensals were found associated with Corallianassa coutierei. However, burrows of Neaxius acanthus in the field typically contained a pair of shrimps, up to 8 individuals of the commensal bivalve Barrimysia cumingii and large numbers of gammarid amphipods. Other animals found associated with the burrow were the goby Austrolethops wardi, a

  1. The influence of wave energy and sediment transport on seagrass distribution

    USGS Publications Warehouse

    Stevens, Andrew W.; Lacy, Jessica R.

    2012-01-01

    A coupled hydrodynamic and sediment transport model (Delft3D) was used to simulate the water levels, waves, and currents associated with a seagrass (Zostera marina) landscape along a 4-km stretch of coast in Puget Sound, WA, USA. A hydroacoustic survey of seagrass percent cover and nearshore bathymetry was conducted, and sediment grain size was sampled at 53 locations. Wave energy is a primary factor controlling seagrass distribution at the site, accounting for 73% of the variability in seagrass minimum depth and 86% of the variability in percent cover along the shallow, sandy portions of the coast. A combination of numerical simulations and a conceptual model of the effect of sea-level rise on the cross-shore distribution of seagrass indicates that the area of seagrass habitat may initially increase and that wave dynamics are an important factor to consider in predicting the effect of sea-level rise on seagrass distributions in wave-exposed areas.

  2. Dugong dugon feeding in tropical Australian seagrass meadows: implications for conservation planning

    PubMed Central

    Coles, Rob G.; Congdon, Bradley C.

    2016-01-01

    Dugongs (Dugong dugon) are listed as vulnerable to extinction due to rapid population reductions caused in part by loss of seagrass feeding meadows. Understanding dugong feeding behaviour in tropical Australia, where the majority of dugongs live, will assist conservation strategies. We examined whether feeding patterns in intertidal seagrass meadows in tropical north-eastern Australia were related to seagrass biomass, species composition and/or nitrogen content. The total biomass of each seagrass species removed by feeding dugongs was measured and compared to its relative availability. Nitrogen concentrations were also determined for each seagrass species present at the sites. Dugongs consumed seagrass species in proportion to their availability, with biomass being the primary determining factor. Species composition and/or nitrogen content influenced consumption to a lesser degree. Conservation plans focused on protecting high biomass intertidal seagrass meadows are likely to be most effective at ensuring the survival of dugong in tropical north-eastern Australia. PMID:27441123

  3. Impact of pond aquaculture effluents on seagrass performance in NE Hainan, tropical China.

    PubMed

    Herbeck, Lucia S; Sollich, Miriam; Unger, Daniela; Holmer, Marianne; Jennerjahn, Tim C

    2014-08-15

    The impact of pond aquaculture effluents on the distribution and performance of seagrasses was examined in NE Hainan, tropical China. Samples were taken along transects in three back-reef areas with different extent of aquaculture production in their hinterland. High δ(15)N in seagrass leaves and epiphytes (6-9‰) similar to values in pond effluents documented aquaculture as dominant nitrogen source in the back-reefs with decreasing impact with distance from shore. Seagrass species abundance, shoot density and biomass were lower and concentrations of nutrients, chlorophyll and suspended matter were higher at nearshore sites with high and moderate pond abundance than at the control site. High epiphyte loads and low δ(34)S in seagrass leaves suggest temporal shading and sulphide poisoning of the nearshore seagrasses. Observed gradients in environmental parameters and seagrass performance indicate that the distance from the pond outlets and size of the adjacent pond agglomeration are major determinants of seagrass degradation.

  4. Quantifying and modelling the carbon sequestration capacity of seagrass meadows--a critical assessment.

    PubMed

    Macreadie, P I; Baird, M E; Trevathan-Tackett, S M; Larkum, A W D; Ralph, P J

    2014-06-30

    Seagrasses are among the planet's most effective natural ecosystems for sequestering (capturing and storing) carbon (C); but if degraded, they could leak stored C into the atmosphere and accelerate global warming. Quantifying and modelling the C sequestration capacity is therefore critical for successfully managing seagrass ecosystems to maintain their substantial abatement potential. At present, there is no mechanism to support carbon financing linked to seagrass. For seagrasses to be recognised by the IPCC and the voluntary C market, standard stock assessment methodologies and inventories of seagrass C stocks are required. Developing accurate C budgets for seagrass meadows is indeed complex; we discuss these complexities, and, in addition, we review techniques and methodologies that will aid development of C budgets. We also consider a simple process-based data assimilation model for predicting how seagrasses will respond to future change, accompanied by a practical list of research priorities.

  5. Dugong dugon feeding in tropical Australian seagrass meadows: implications for conservation planning.

    PubMed

    Tol, Samantha J; Coles, Rob G; Congdon, Bradley C

    2016-01-01

    Dugongs (Dugong dugon) are listed as vulnerable to extinction due to rapid population reductions caused in part by loss of seagrass feeding meadows. Understanding dugong feeding behaviour in tropical Australia, where the majority of dugongs live, will assist conservation strategies. We examined whether feeding patterns in intertidal seagrass meadows in tropical north-eastern Australia were related to seagrass biomass, species composition and/or nitrogen content. The total biomass of each seagrass species removed by feeding dugongs was measured and compared to its relative availability. Nitrogen concentrations were also determined for each seagrass species present at the sites. Dugongs consumed seagrass species in proportion to their availability, with biomass being the primary determining factor. Species composition and/or nitrogen content influenced consumption to a lesser degree. Conservation plans focused on protecting high biomass intertidal seagrass meadows are likely to be most effective at ensuring the survival of dugong in tropical north-eastern Australia.

  6. Landscape configuration modulates carbon storage in seagrass sediments

    NASA Astrophysics Data System (ADS)

    Ricart, Aurora M.; Pérez, Marta; Romero, Javier

    2017-02-01

    Climate change has increased interest in seagrass systems as natural carbon sinks and recent studies have estimated the carbon stocks associated with seagrass meadows. However, the factors that affect their variability remain poorly understood. This paper assesses how landscape-level attributes (patch size and matrix composition) influence carbon storage in seagrass sediments. We quantified the organic carbon (Corg) content and other geochemical properties (δ13C and particle size) in surface sediments of continuous Posidonia oceanica meadows, patchy meadows interspersed with rocky-algal reefs and patchy meadows on sedimentary bottoms. We also took samples of potential carbon sources for isotopic composition determination. Our results indicate that the continuous meadows accumulated larger amounts of Corg than patchy meadows, whether embedded in a rock or sand matrix. The Corg from continuous meadows was also more 13C enriched, which suggests that a high proportion of the carbon was derived from plant material (autochthonous sources); in contrast in patchy meadows (especially in a sand matrix), lower δ13C values indicated a higher contribution from allochthonous sources (mainly suspended particulate organic matter, SPOM). These findings suggest that the sediment of continuous meadows stores more Corg in than that of patchy meadows. This is probably due to the increased contribution from seagrass leaves, which are much more refractory than SPOM. In general, certain landscape configurations, and especially patchiness, appear to reduce the carbon storage capacity of seagrasses. Since the current decline of seagrass is leading to habitat fragmentation, our results increase the argument for the promotion of effective measures to preserve the integrity of these natural carbon sinks.

  7. Photorespiration and carbon limitation determine productivity in temperate seagrasses.

    PubMed

    Buapet, Pimchanok; Rasmusson, Lina M; Gullström, Martin; Björk, Mats

    2013-01-01

    The gross primary productivity of two seagrasses, Zostera marina and Ruppia maritima, and one green macroalga, Ulva intestinalis, was assessed in laboratory and field experiments to determine whether the photorespiratory pathway operates at a substantial level in these macrophytes and to what extent it is enhanced by naturally occurring shifts in dissolved inorganic carbon (DIC) and O2 in dense vegetation. To achieve these conditions in laboratory experiments, seawater was incubated with U. intestinalis in light to obtain a range of higher pH and O2 levels and lower DIC levels. Gross photosynthetic O2 evolution was then measured in this pretreated seawater (pH, 7.8-9.8; high to low DIC:O2 ratio) at both natural and low O2 concentrations (adjusted by N2 bubbling). The presence of photorespiration was indicated by a lower gross O2 evolution rate under natural O2 conditions than when O2 was reduced. In all three macrophytes, gross photosynthetic rates were negatively affected by higher pH and lower DIC. However, while both seagrasses exhibited significant photorespiratory activity at increasing pH values, the macroalga U. intestinalis exhibited no such activity. Rates of seagrass photosynthesis were then assessed in seawater collected from the natural habitats (i.e., shallow bays characterized by high macrophyte cover and by low DIC and high pH during daytime) and compared with open baymouth water conditions (where seawater DIC is in equilibrium with air, normal DIC, and pH). The gross photosynthetic rates of both seagrasses were significantly higher when incubated in the baymouth water, indicating that these grasses can be significantly carbon limited in shallow bays. Photorespiration was also detected in both seagrasses under shallow bay water conditions. Our findings indicate that natural carbon limitations caused by high community photosynthesis can enhance photorespiration and cause a significant decline in seagrass primary production in shallow waters.

  8. Resource distribution influences positive edge effects in a seagrass fish.

    PubMed

    Macreadie, Peter I; Hindell, Jeremy S; Keough, Michael J; Jenkins, Gregory P; Connolly, Rod M

    2010-07-01

    According to conceptual models, the distribution of resources plays a critical role in determining how organisms distribute themselves near habitat edges. These models are frequently used to achieve a mechanistic understanding of edge effects, but because they are based predominantly on correlative studies, there is need for a demonstration of causality, which is best done through experimentation. Using artificial seagrass habitat as an experimental system, we determined a likely mechanism underpinning edge effects in a seagrass fish. To test for edge effects, we measured fish abundance at edges (0-0.5 m) and interiors (0.5-1 m) of two patch configurations: continuous (single, continuous 9-m2 patches) and patchy (four discrete 1-m2 patches within a 9-m2 area). In continuous configurations, pipefish (Stigmatopora argus) were three times more abundant at edges than interiors (positive edge effect), but in patchy configurations there was no difference. The lack of edge effect in patchy configurations might be because patchy seagrass consisted entirely of edge habitat. We then used two approaches to test whether observed edge effects in continuous configurations were caused by increased availability of food at edges. First, we estimated the abundance of the major prey of pipefish, small crustaceans, across continuous seagrass configurations. Crustacean abundances were highest at seagrass edges, where they were 16% greater than in patch interiors. Second, we supplemented interiors of continuous treatment patches with live crustaceans, while control patches were supplemented with seawater. After five hours of supplementation, numbers of pipefish were similar between edges and interiors of treatment patches, while the strong edge effects were maintained in controls. This indicated that fish were moving from patch edges to interiors in response to food supplementation. These approaches strongly suggest that a numerically dominant fish species is more abundant at seagrass

  9. Ontogenetic habitat use by mangrove/seagrass-associated coral reef fishes shows flexibility in time and space

    NASA Astrophysics Data System (ADS)

    Kimirei, Ismael A.; Nagelkerken, Ivan; Griffioen, Ben; Wagner, Coen; Mgaya, Yunus D.

    2011-03-01

    Tropical shallow-water habitats such as mangroves and seagrass beds are widely acknowledged as important juvenile habitats for various coral reef fish species, most of which are commercially important to fisheries. Spatio-temporal variability in ontogenetic habitat use by fish among these tropical coastal ecosystems has rarely been investigated, yet there are sufficient reasons to believe that this plays an important role. In the present study, we test the spatio-temporal variability in patterns of ontogenetic habitat use by some mangrove/seagrass-associated coral reef fishes ( Lethrinus harak, Lethrinus lentjan, Lutjanus fulviflamma and Siganus sutor). Abundances of these four species were investigated during two years in Tanzanian coastal waters, using underwater visual census in mangrove, seagrass, shallow and deep mudflat, and shallow and deep coral reef habitats. The study covered four distinct seasons of the year and was done at two spatially separated (>40 km) locations. Averaged across locations, seasons and years, juveniles (≤10 cm length) of the four study species had significantly higher relative densities in shallow-water (mangroves and seagrass beds) than in deep-water habitats (deep mudflats or coral reefs), whereas the opposite pattern was found for the adults (>15 cm). These findings suggest a strong and general pattern of ontogenetic habitat shifts from shallow- to deep-water habitats. However, specific habitat-use patterns of juveniles as well as adults differed significantly in time and space. Various species showed subtle to considerable flexibility in juvenile as well as adult habitat use across seasons, years, or at different locations. Furthermore, for some species the data suggest presence of ontogenetic habitat shifts at one location but lack thereof at the other location. In summary, ontogenetic habitat use needs to be considered at various spatial and temporal scales for the interpretation of habitat utilization by fish during different

  10. Local Knowledge and Conservation of Seagrasses in the Tamil Nadu State of India

    PubMed Central

    2011-01-01

    Local knowledge systems are not considered in the conservation of fragile seagrass marine ecosystems. In fact, little is known about the utility of seagrasses in local coastal communities. This is intriguing given that some local communities rely on seagrasses to sustain their livelihoods and have relocated their villages to areas with a rich diversity and abundance of seagrasses. The purpose of this study is to assist in conservation efforts regarding seagrasses through identifying Traditional Ecological Knowledge (TEK) from local knowledge systems of seagrasses from 40 coastal communities along the eastern coast of India. We explore the assemblage of scientific and local traditional knowledge concerning the 1. classification of seagrasses (comparing scientific and traditional classification systems), 2. utility of seagrasses, 3. Traditional Ecological Knowledge (TEK) of seagrasses, and 4. current conservation efforts for seagrass ecosystems. Our results indicate that local knowledge systems consist of a complex classification of seagrass diversity that considers the role of seagrasses in the marine ecosystem. This fine-scaled ethno-classification gives rise to five times the number of taxa (10 species = 50 local ethnotaxa), each with a unique role in the ecosystem and utility within coastal communities, including the use of seagrasses for medicine (e.g., treatment of heart conditions, seasickness, etc.), food (nutritious seeds), fertilizer (nutrient rich biomass) and livestock feed (goats and sheep). Local communities are concerned about the loss of seagrass diversity and have considerable local knowledge that is valuable for conservation and restoration plans. This study serves as a case study example of the depth and breadth of local knowledge systems for a particular ecosystem that is in peril. Key words: local health and nutrition, traditional ecological knowledge (TEK), conservation and natural resources management, consensus, ethnomedicine, ethnotaxa

  11. Assessing Gear Modifications Needed to Optimize Yields in a Heavily Exploited, Multi-Species, Seagrass and Coral Reef Fishery

    PubMed Central

    Hicks, Christina C.; McClanahan, Timothy R.

    2012-01-01

    Effective management is necessary if small-scale fisheries, such as those found in mixed habitats including seagrass and coral reefs, are to continue providing food for many of the poorest communities of the world. Gear-based management, although under represented and under studied, has the potential to be adaptive, address multiple objectives, and be crafted to the socio-economic setting. Management effectiveness in seagrass and coral reef fisheries has generally been evaluated at the scale of the fish community. However, community level indicators can mask species-specific declines that provide significant portions of the fisheries yields and income. Using a unique dataset, containing ten years of species level length frequency catch data from a multi-gear, multi-species seagrass and coral reef fishery in Kenya, we evaluate species specific fishery statuses, compare gear use to gear regulations and estimate the potential needs for further gear restrictions. Despite the high diversity of the fishery, fifteen species represented over 90% of the catch, and only three species represented 60% of the catch. The three most abundant species in the catch, Lethrinus lentjan (Lacepède), Siganus sutor (Valenciennes) and Leptoscarus vaigiensis (Quoy & Gaimard) all showed evidence of growth overfishing. Lethrinus lentjan, with an exploitation rate of 0.82, also shows evidence of recruitment overfishing. Current legal but weakly enforced gear restrictions are capable of protecting a significant portion of the catch up to maturity but optimization of yield will require that the current mesh size be increased from 6.3 to 8.8 and 9.2 cm to increase yields of L. lentjan and S. sutor, respectively. Given the difficulties of enforcing mesh size, we recommend that the economic benefits of these larger mesh sizes be communicated and enforced through co-management. This abstract is also available in Kiswahili (Abstract S1). PMID:22574133

  12. Assessing gear modifications needed to optimize yields in a heavily exploited, multi-species, seagrass and coral reef fishery.

    PubMed

    Hicks, Christina C; McClanahan, Timothy R

    2012-01-01

    Effective management is necessary if small-scale fisheries, such as those found in mixed habitats including seagrass and coral reefs, are to continue providing food for many of the poorest communities of the world. Gear-based management, although under represented and under studied, has the potential to be adaptive, address multiple objectives, and be crafted to the socio-economic setting. Management effectiveness in seagrass and coral reef fisheries has generally been evaluated at the scale of the fish community. However, community level indicators can mask species-specific declines that provide significant portions of the fisheries yields and income. Using a unique dataset, containing ten years of species level length frequency catch data from a multi-gear, multi-species seagrass and coral reef fishery in Kenya, we evaluate species specific fishery statuses, compare gear use to gear regulations and estimate the potential needs for further gear restrictions. Despite the high diversity of the fishery, fifteen species represented over 90% of the catch, and only three species represented 60% of the catch. The three most abundant species in the catch, Lethrinus lentjan (Lacepède), Siganus sutor (Valenciennes) and Leptoscarus vaigiensis (Quoy & Gaimard) all showed evidence of growth overfishing. Lethrinus lentjan, with an exploitation rate of 0.82, also shows evidence of recruitment overfishing. Current legal but weakly enforced gear restrictions are capable of protecting a significant portion of the catch up to maturity but optimization of yield will require that the current mesh size be increased from 6.3 to 8.8 and 9.2 cm to increase yields of L. lentjan and S. sutor, respectively. Given the difficulties of enforcing mesh size, we recommend that the economic benefits of these larger mesh sizes be communicated and enforced through co-management. This abstract is also available in Kiswahili (Abstract S1).

  13. CONTROLS OF SEAGRASS EPIPHYTE ABUNDANCE: DOES LIGHT TRUMP NUTRIENTS?

    EPA Science Inventory

    Epiphytes on seagrass growing in the lower intertidal were examined along an estuarine gradient within Yaquina Bay, Oregon over a period of 4 years. The Yaquina Estuary receives high levels of nutrients from the watershed during the wet season and from the ocean during the dry s...

  14. 50 CFR 226.213 - Critical habitat for Johnson's seagrass.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 50 Wildlife and Fisheries 9 2011-10-01 2011-10-01 false Critical habitat for Johnson's seagrass. 226.213 Section 226.213 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS DESIGNATED CRITICAL HABITAT §...

  15. 50 CFR 226.213 - Critical habitat for Johnson's seagrass.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 50 Wildlife and Fisheries 10 2012-10-01 2012-10-01 false Critical habitat for Johnson's seagrass. 226.213 Section 226.213 Wildlife and Fisheries NATIONAL MARINE FISHERIES SERVICE, NATIONAL OCEANIC AND ATMOSPHERIC ADMINISTRATION, DEPARTMENT OF COMMERCE MARINE MAMMALS DESIGNATED CRITICAL HABITAT §...

  16. Seagrass Ecosystem Services and Their Variability across Genera and Geographical Regions.

    PubMed

    Mtwana Nordlund, Lina; Koch, Evamaria W; Barbier, Edward B; Creed, Joel C

    2016-01-01

    Threats to and loss of seagrass ecosystems globally, impact not only natural resources but also the lives of people who directly or indirectly depend on these systems. Seagrass ecosystems play a multi-functional role in human well-being, e.g. food through fisheries, control of erosion and protection against floods. Quantifying these services reveals their contributions to human well-being and helps justify seagrass conservation. There has been no comprehensive assessment as to whether seagrass ecosystem services are perceived to vary over the globe or amongst genera. Our study compiles the most complete list of ecosystem services provided by seagrasses so far, including bioregional- and genus-specific information from expert opinion and published studies. Several seagrass ecosystem services vary considerably in their (known) provision across genera and over the globe. Seagrasses genera are clearly not all equal with regard to the ecosystem services they provide. As seagrass genera are not evenly distributed over all bioregions, the presence of an ecosystem service sometimes depends on the genera present. Larger sized seagrass genera (e.g. Posidonia, Enhalus) are perceived to provide more substantial and a wider variety of ecosystem services than smaller species (e.g. Halophila, Lepilaena). Nevertheless, smaller species provide important services. Our findings point out data gaps, provide new insight for more efficient management and recommend caution in economic valuation of seagrass services worldwide.

  17. Heavy metal enrichment in the seagrasses of Lakshadweep group of islands--a multivariate statistical analysis.

    PubMed

    Thangaradjou, T; Raja, S; Subhashini, Pon; Nobi, E P; Dilipan, E

    2013-01-01

    An assessment on heavy metal (Al, Cd, Co, Cr, Cu, Fe, Mg, Mn, Ni, Pb and Zn) accumulation by seven seagrass species of Lakshadweep group of islands was carried out using multivariate statistical tools like principal component analysis (PCA) and cluster analysis (CA). Among all the metals, Mg and Al were determined in higher concentration in all the seagrasses, and their values varied with respect to different seagrass species. The concentration of the four toxic heavy metals (Cd, Pb, Zn and Cu) was found higher in all the seagrasses when compared with the background values of seagrasses from Flores Sea, Indonesia. The contamination factor of these four heavy metals ranged as Cd (1.97-12.5), Cu (0.73-4.40), Pb (2.3-8.89) and Zn (1.27-2.787). In general, the Pollution Load Index (PLI) calculated was found to be maximum for Halophila decipiens (58.2). Results revealed that Halophila decipiens is a strong accumulator of heavy metals, followed by Halodule uninervis and Halodule pinifolia, among all the tested seagrasses. Interestingly, the small-leaved seagrasses were found to be efficient in heavy metal accumulation than the large-leaved seagrass species. Thus, seagrasses can better be used for biomonitoring, and seagrasses can be used as the heavy metal sink as the biomass take usually long term to get remineralize in nature.

  18. Seagrass Ecosystem Services and Their Variability across Genera and Geographical Regions

    PubMed Central

    Mtwana Nordlund, Lina; Barbier, Edward B.; Creed, Joel C.

    2016-01-01

    Threats to and loss of seagrass ecosystems globally, impact not only natural resources but also the lives of people who directly or indirectly depend on these systems. Seagrass ecosystems play a multi-functional role in human well-being, e.g. food through fisheries, control of erosion and protection against floods. Quantifying these services reveals their contributions to human well-being and helps justify seagrass conservation. There has been no comprehensive assessment as to whether seagrass ecosystem services are perceived to vary over the globe or amongst genera. Our study compiles the most complete list of ecosystem services provided by seagrasses so far, including bioregional- and genus-specific information from expert opinion and published studies. Several seagrass ecosystem services vary considerably in their (known) provision across genera and over the globe. Seagrasses genera are clearly not all equal with regard to the ecosystem services they provide. As seagrass genera are not evenly distributed over all bioregions, the presence of an ecosystem service sometimes depends on the genera present. Larger sized seagrass genera (e.g. Posidonia, Enhalus) are perceived to provide more substantial and a wider variety of ecosystem services than smaller species (e.g. Halophila, Lepilaena). Nevertheless, smaller species provide important services. Our findings point out data gaps, provide new insight for more efficient management and recommend caution in economic valuation of seagrass services worldwide. PMID:27732600

  19. Meadow fragmentation and reproductive output of the SE Asian seagrass Enhalus acoroides [rapid communication

    NASA Astrophysics Data System (ADS)

    Vermaat, Jan E.; Rollon, Rene N.; Lacap, Cristina Day A.; Billot, Claire; Alberto, Filipe; Nacorda, Hildie M. E.; Wiegman, Frank; Terrados, Jorge

    2004-11-01

    Flower and fruit production of the abundant, tall, long-lived, dioecious, surface-pollinating seagrass species Enhalus acoroides (L.) Royle were estimated at seven sites in the reef flats off Bolinao (NW Luzon, The Philippines) featuring different fragmentation of the seagrass meadows. Fragmentation of the seagrass meadow was quantified as cover of E. acoroides and all seagrass species present in 20×20 m plots. E. acoroides and overall seagrass cover were correlated positively. The proportion of female flowers of E. acoroides that developed a fruit increased sharply as overall seagrass cover was around 50%. Apparent sex ratio bore no relationship with overall seagrass cover. This threshold-type of relationship suggests that fragmentation of seagrass meadows can have a major effect on the reproductive output of this species. A possible mechanism underlying these results would be a non-linear increase of the efficiency of trapping the surface-dispersed pollen with increasing seagrass canopy density. This provides the first evidence based on real data that fragmentation can affect the population dynamics of seagrass species.

  20. Sustainable Management of Seagrass Meadows: the GEOSS AIP-6 Pilot

    NASA Astrophysics Data System (ADS)

    Santoro, Mattia; Pastres, Roberto; Zucchetta, Matteo; Venier, Chiara; Roncella, Roberto; Bigagli, Lorenzo; Mangin, Antoine; Amine Taji, Mohamed; Gonzalo Malvarez, Gonzalo; Nativi, Stefano

    2014-05-01

    Seagrass meadows (marine angiosperm plants) occupy less than 0.2% of the global ocean surface, annually store about 10-18% of the so-called "Blue Carbon", i.e. the Carbon stored in coastal vegetated areas. Recent literature estimates that the flux to the long-term carbon sink in seagrasses represents 10-20% of seagrasses global average production. Such figures can be translated into economic benefits, taking into account that a ton of carbon dioxide in Europe is paid at around 15 € in the carbon market. This means that the organic carbon retained in seagrass sediments in the Mediterranean is worth 138 - 1128 billion €, which represents 6-23 € per square meter. This is 9-35 times more than one square meter of tropical forest soil (0.66 € per square meter), or 5-17 times when considering both the above and the belowground compartments in tropical forests. According the most conservative estimations, about 10% of the Mediterranean meadows have been lost during the last century. To estimate seagrass meadows distribution, a Species Distribution Model (SDM) can be used. SDM is a tool that is used to evaluate the potential distribution of a given species (e.g. Posidonia oceanica for seagrass) on the basis of the features (bio-chemical-physical parameters) of the studied environment. In the framework of the GEOSS (Global Earth Observation System of Systems) initiative, the FP7 project MEDINA developed a showcase as part of the GEOSS Architecture Interoperability Pilot - phase 6 (AIP-6). The showcase aims at providing a tool for the sustainable management of seagrass meadows along the Mediterranean coastline by integrating the SDM with available GEOSS resources. This way, the required input data can be searched, accessed and ingested into the model leveraging the brokering framework of the GEOSS Common Infrastructure (GCI). This framework is comprised of a set of middle-ware components (Brokers) that are in charge of implementing the needed interoperability

  1. Seagrass meadows as a globally significant carbonate reservoir

    NASA Astrophysics Data System (ADS)

    Mazarrasa, I.; Marbà, N.; Lovelock, C. E.; Serrano, O.; Lavery, P. S.; Fourqurean, J. W.; Kennedy, H.; Mateo, M. A.; Krause-Jensen, D.; Steven, A. D. L.; Duarte, C. M.

    2015-08-01

    There has been growing interest in quantifying the capacity of seagrass ecosystems to act as carbon sinks as a natural way of offsetting anthropogenic carbon emissions to the atmosphere. However, most of the efforts have focused on the particulate organic carbon (POC) stocks and accumulation rates and ignored the particulate inorganic carbon (PIC) fraction, despite important carbonate pools associated with calcifying organisms inhabiting the meadows, such as epiphytes and benthic invertebrates, and despite the relevance that carbonate precipitation and dissolution processes have in the global carbon cycle. This study offers the first assessment of the global PIC stocks in seagrass sediments using a synthesis of published and unpublished data on sediment carbonate concentration from 403 vegetated and 34 adjacent un-vegetated sites. PIC stocks in the top 1 m of sediment ranged between 3 and 1660 Mg PIC ha-1, with an average of 654 ± 24 Mg PIC ha-1, exceeding those of POC reported in previous studies by about a factor of 5. Sedimentary carbonate stocks varied across seagrass communities, with meadows dominated by Halodule, Thalassia or Cymodocea supporting the highest PIC stocks, and tended to decrease polewards at a rate of -8 ± 2 Mg PIC ha-1 per degree of latitude (general linear model, GLM; p < 0.0003). Using PIC concentrations and estimates of sediment accretion in seagrass meadows, the mean PIC accumulation rate in seagrass sediments is found to be 126.3 ± 31.05 g PIC m-2 yr-1. Based on the global extent of seagrass meadows (177 000 to 600 000 km2), these ecosystems globally store between 11 and 39 Pg of PIC in the top metre of sediment and accumulate between 22 and 75 Tg PIC yr-1, representing a significant contribution to the carbonate dynamics of coastal areas. Despite the fact that these high rates of carbonate accumulation imply CO2 emissions from precipitation, seagrass meadows are still strong CO2 sinks as demonstrated by the comparison of carbon (PIC

  2. The Art of Abstracting.

    ERIC Educational Resources Information Center

    Cremmins, Edward T.

    A three-stage analytical reading method for the composition of informative and indicative abstracts by authors and abstractors is presented in this monograph, along with background information on the abstracting process and a discussion of professional considerations in abstracting. An introduction to abstracts and abstracting precedes general…

  3. Coastal nitrogen plumes and their relationship with seagrass distribution

    NASA Astrophysics Data System (ADS)

    Fernandes, Milena B.; Benger, Simon; Stuart-Williams, Hilary; Gaylard, Sam; Bryars, Simon

    2015-12-01

    Urbanised coastlines are affected by cumulative impacts from a variety of anthropogenic stressors, but spatial information on the distribution of these stressors at the local scale is scarce, hindering the ability of managers to prioritise mitigation options. This work investigated the spatial footprint of land-based nitrogen discharges to a metropolitan coastline and assessed the potential role of this stressor alone on seagrass dynamics at the scale of the ecosystem. The macroalga Caulocystis cephalornithos was used as a time-integrative sampler of nitrogen in the water column over 202 sites monitored across an area of ˜800 km2. The stable isotopic signature of nitrogen in tissues (δ15N) was used to map plumes of anthropogenic origin. The surface area of these plumes was found to be proportional to nitrogen loads from land. The largest plume was associated with discharges from an industrialised estuary and a wastewater treatment plant, where a monthly nitrogen load in excess of 110 tonnes affected an area >80 km2. The location and size of the plumes changed with seasons as a result of wind forcing and rainfall/wastewater reuse. The location of the plumes was compared to published seagrass distribution obtained from video transects. Dense seagrass meadows only occurred in areas unimpacted by plumes throughout the year, mostly in shallow (<5 m) regions for Amphibolis antarctica, and deeper (5-10 m) for Posidonia sp., possibly as a result of this species higher tolerance of low light conditions. This higher tolerance might also explain why Posidonia sp. is observed to preferentially recolonise areas of previous loss in the region. While a decrease in the spatial footprint of nutrient plumes has created conditions for natural seagrass recolonisation in some areas, it did not halt seagrass loss in others, suggesting the influence of additional stressors such as wave dynamics and light attenuation due to turbid/coloured stormwater.

  4. Photosynthetic activity buffers ocean acidification in seagrass meadows

    NASA Astrophysics Data System (ADS)

    Hendriks, I. E.; Olsen, Y. S.; Ramajo, L.; Basso, L.; Steckbauer, A.; Moore, T. S.; Howard, J.; Duarte, C. M.

    2014-01-01

    Macrophytes growing in shallow coastal zones characterised by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH changes in shallow (5-12 m) seagrass (Posidonia oceanica) meadows spanning 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturation state (ΩAr)) and O2 within the meadows displayed strong diel variability driven by primary productivity, and changes in chemistry were related to structural parameters of the meadow, in particular, the leaf surface area available for photosynthesis (LAI). LAI was positively correlated to mean, max and range pHNBS and max and range ΩAr. In June, vertical mixing (as Turbulent Kinetic Energy) influenced max and min ΩAr, while in September there was no effect of hydrodynamics on the carbonate system within the canopy. Max and range ΩAr within the meadow showed a positive trend with the calcium carbonate load of the leaves, pointing to a possible link between structural parameters, ΩAr and carbonate deposition. Calcifying organisms, e.g. epiphytes with carbonate skeletons, may benefit from the modification of the carbonate system by the meadow. There is, however, concern for the ability of seagrasses to provide modifications of similar importance in the future. The predicted decline of seagrass meadows may alter the scope for alteration of pH within a seagrass meadow and in the water column above the meadow, particularly if shoot density and biomass decline, on which LAI is based. Organisms associated with seagrass communities may therefore suffer from the loss of pH buffering capacity in degraded meadows.

  5. Towards understanding temporal and spatial dynamics of seagrass landscapes using time-series remote sensing

    NASA Astrophysics Data System (ADS)

    Lyons, Mitchell B.; Roelfsema, Chris M.; Phinn, Stuart R.

    2013-03-01

    The spatial and temporal dynamics of seagrasses have been well studied at the leaf to patch scales, however, the link to large spatial extent landscape and population dynamics is still unresolved in seagrass ecology. Traditional remote sensing approaches have lacked the temporal resolution and consistency to appropriately address this issue. This study uses two high temporal resolution time-series of thematic seagrass cover maps to examine the spatial and temporal dynamics of seagrass at both an inter- and intra-annual time scales, one of the first globally to do so at this scale. Previous work by the authors developed an object-based approach to map seagrass cover level distribution from a long term archive of Landsat TM and ETM+ images on the Eastern Banks (≈200 km2), Moreton Bay, Australia. In this work a range of trend and time-series analysis methods are demonstrated for a time-series of 23 annual maps from 1988 to 2010 and a time-series of 16 monthly maps during 2008-2010. Significant new insight was presented regarding the inter- and intra-annual dynamics of seagrass persistence over time, seagrass cover level variability, seagrass cover level trajectory, and change in area of seagrass and cover levels over time. Overall we found that there was no significant decline in total seagrass area on the Eastern Banks, but there was a significant decline in seagrass cover level condition. A case study of two smaller communities within the Eastern Banks that experienced a decline in both overall seagrass area and condition are examined in detail, highlighting possible differences in environmental and process drivers. We demonstrate how trend and time-series analysis enabled seagrass distribution to be appropriately assessed in context of its spatial and temporal history and provides the ability to not only quantify change, but also describe the type of change. We also demonstrate the potential use of time-series analysis products to investigate seagrass growth and

  6. Effects of CO(2) enrichment on photosynthesis, growth, and biochemical composition of seagrass Thalassia hemprichii (Ehrenb.) Aschers.

    PubMed

    Jiang, Zhi Jian; Huang, Xiao-Pin; Zhang, Jing-Ping

    2010-10-01

    The effects of CO₂ enrichment on various ecophysiological parameters of tropical seagrass Thalassia hemprichii (Ehrenb.) Aschers were tested. T. hemprichii, collected from a seagrass bed in Xincun Bay, Hainan island of Southern China, was cultured at 4 CO₂ (aq) concentrations in flow-through seawater aquaria bubbled with CO₂ . CO₂ enrichment considerably enhanced the relative maximum electron transport rate (RETR(max) ) and minimum saturating irradiance (E(k) ) of T. hemprichii. Leaf growth rate of CO₂ -enriched plants was significantly higher than that in unenriched treatment. Nonstructural carbohydrates (NSC) of T. hemprichii, especially in belowground tissues, increased strongly with elevated CO₂ (aq), suggesting a translocation of photosynthate from aboveground to belowground tissues. Carbon content in belowground tissues showed a similar response with NSC, while in aboveground tissues, carbon content was not affected by CO₂ treatments. In contrast, with increasing CO₂ (aq), nitrogen content in aboveground tissues markedly decreased, but nitrogen content in belowground was nearly constant. Carbon: nitrogen ratio in both tissues were obviously enhanced by increasing CO₂ (aq). Thus, these results indicate that T. hemprichii may respond positively to CO₂ -induced acidification of the coastal ocean. Moreover, the CO₂ -stimulated improvement of photosynthesis and NSC content may partially offset negative effects of severe environmental disturbance such as underwater light reduction.

  7. Seagrass meadows globally as a coupled social-ecological system: implications for human wellbeing.

    PubMed

    Cullen-Unsworth, Leanne C; Nordlund, Lina Mtwana; Paddock, Jessica; Baker, Susan; McKenzie, Len J; Unsworth, Richard K F

    2014-06-30

    Seagrass ecosystems are diminishing worldwide and repeated studies confirm a lack of appreciation for the value of these systems. In order to highlight their value we provide the first discussion of seagrass meadows as a coupled social-ecological system on a global scale. We consider the impact of a declining resource on people, including those for whom seagrass meadows are utilised for income generation and a source of food security through fisheries support. Case studies from across the globe are used to demonstrate the intricate relationship between seagrass meadows and people that highlight the multi-functional role of seagrasses in human wellbeing. While each case underscores unique issues, these examples simultaneously reveal social-ecological coupling that transcends cultural and geographical boundaries. We conclude that understanding seagrass meadows as a coupled social-ecological system is crucial in carving pathways for social and ecological resilience in light of current patterns of local to global environmental change.

  8. Non-native seagrass Halophila stipulacea forms dense mats under eutrophic conditions in the Caribbean

    NASA Astrophysics Data System (ADS)

    van Tussenbroek, B. I.; van Katwijk, M. M.; Bouma, T. J.; van der Heide, T.; Govers, L. L.; Leuven, R. S. E. W.

    2016-09-01

    Seagrasses comprise 78 species and are rarely invasive. But the seagrass Halophila stipulacea, firstly recorded in the Caribbean in the year 2002, has spread quickly throughout the region. Previous works have described this species as invasive in the Caribbean, forming dense mats that exclude native seagrass species. During a reconnaissance field survey of Caribbean seagrass meadows at the islands of Bonaire and Sint Maarten in 2013, we observed that this species was only extremely dense at 5 out of 10 studied meadows. Compared to areas with sparse growth of H. stipulacea, these dense meadows showed consistently higher nutrient concentrations, as indicated by higher leaf tissue N contents of the seagrass Thalassia testudinum (dense when C:N < 22.5) and sediments (dense when %N > 11.3). Thus, the potential invasiveness of this non-native seagrass most likely depends on the environmental conditions, especially the nutrient concentrations.

  9. Resilience of Zostera muelleri seagrass to small-scale disturbances: the relative importance of asexual versus sexual recovery

    PubMed Central

    Macreadie, Peter I; York, Paul H; Sherman, Craig DH

    2014-01-01

    beds (as opposed to bare areas arising from disturbance) must be the mechanism responsible for maintaining the observed mixed genetic composition of Z. muelleri seagrass meadows. PMID:24634729

  10. Coastal retreat and improved water quality mitigate losses of seagrass from sea level rise.

    PubMed

    Saunders, Megan I; Leon, Javier; Phinn, Stuart R; Callaghan, David P; O'Brien, Katherine R; Roelfsema, Chris M; Lovelock, Catherine E; Lyons, Mitchell B; Mumby, Peter J

    2013-08-01

    The distribution and abundance of seagrass ecosystems could change significantly over the coming century due to sea level rise (SLR). Coastal managers require mechanistic understanding of the processes affecting seagrass response to SLR to maximize their conservation and associated provision of ecosystem services. In Moreton Bay, Queensland, Australia, vast seagrass meadows supporting populations of sea turtles and dugongs are juxtaposed with the multiple stressors associated with a large and rapidly expanding human population. Here, the interactive effects of predicted SLR, changes in water clarity, and land use on future distributions of seagrass in Moreton Bay were quantified. A habitat distribution model of present day seagrass in relation to benthic irradiance and wave height was developed which correctly classified habitats in 83% of cases. Spatial predictions of seagrass and presence derived from the model and bathymetric data were used to initiate a SLR inundation model. Bathymetry was iteratively modified based on SLR and sedimentary accretion in seagrass to simulate potential seagrass habitat at 10 year time steps until 2100. The area of seagrass habitat was predicted to decline by 17% by 2100 under a scenario of SLR of 1.1 m. A scenario including the removal of impervious surfaces, such as roads and houses, from newly inundated regions, demonstrated that managed retreat of the shoreline could potentially reduce the overall decline in seagrass habitat to just 5%. The predicted reduction in area of seagrass habitat could be offset by an improvement in water clarity of 30%. Greater improvements in water clarity would be necessary for larger magnitudes of SLR. Management to improve water quality will provide present and future benefits to seagrasses under climate change and should be a priority for managers seeking to compensate for the effects of global change on these valuable habitats.

  11. Challenges of remote sensing for quantifying changes in large complex seagrass environments

    NASA Astrophysics Data System (ADS)

    Roelfsema, Chris; Kovacs, Eva M.; Saunders, Megan I.; Phinn, Stuart; Lyons, Mitchell; Maxwell, Paul

    2013-11-01

    Managing seagrass environments and understanding and responding to coastal impacts such as floods or cyclones, requires assessment of seagrass distribution and its biophysical properties in time and space. Comparable assessments of seagrass distribution over time are often lacking as the information is present for separate dates, or created following different mapping approaches, and this makes it difficult to conduct quantitative comparisons. We provide an assessment of available data sets and approaches, and their suitability for monitoring and quantifying change in seagrass percentage cover and extent for a large coastal embayment (Moreton Bay, Australia, 1582 km2). Seagrass percentage cover maps were created for 2011 and 2004 and compared to map and measure the extent of seagrass percentage cover change, and changes in the extent of seagrass environments. Total extent of seagrass was shown to be higher in 2011 compared to 2004. Potential sources of these differences may be: mapping inaccuracy; actual change in extent and cover; and, monthly to seasonal variations in seagrass cover. A qualitative comparison of the 2004 and 2011 maps was performed against maps of seagrass extent maps from 1975, 1986 and 1999, which were created using a range of different methods and data. The output maps show changes in seagrass extent, but a lack of detail arising from variable mapping methods and differing mapping extents prevented a reliable comparison. We conclude that robust mapping of seasonal and inter-annual variation in seagrass percentage cover distribution or extent, as well as impacts of episodic and stochastic disturbance events, requires a thorough understanding of the mapping approaches used so that data sets can be compared. Additional complimentary information is required to help understand the drivers of changes.

  12. Seagrass as pasture for seacows: Landscape-level dugong habitat evaluation

    NASA Astrophysics Data System (ADS)

    Sheppard, James K.; Lawler, Ivan R.; Marsh, Helene

    2007-01-01

    A 24 km 2 seagrass meadow in Hervey Bay, Queensland, Australia, was confirmed as important dugong habitat by a satellite tracking study. Marine videography, near-infrared spectroscopy (NIRS) and geographic information systems (GIS) were used to survey, analyse and map seagrass species composition, nutrient profile and patch structure at high resolution (200 m). Five species of seagrass covered 91% of the total habitat area. The total above and below-ground seagrass biomass was estimated to be 222.7 ± 19.6 t dry-weight. Halodule uninervis dominated the pasture (81.8%, 162.2 t), followed by Halophila ovalis (35.3%, 16.5 t), Zostera capricorni (15.9%, 22.2 t), Halophila spinulosa (14.5%, 21.9 t), and traces of Halodule pinifolia. Because seagrass distributions overlapped, their combined percentage totalled >100% of the survey area. The seagrass formed a continuous meadow of varying density. Abiotic variables explained relatively little of the spatial patterns in the seagrass. For all seagrass species, the above-ground component (shoots and leaves) possessed greater total nitrogen than the below-ground component (roots and rhizomes), which possessed greater total starch. Because of the relatively low intraspecific variation in nutrient composition, nutrients were concentrated according to seagrass biomass density. Halodule uninervis was the most nutritious seagrass species because of its superior whole-plant nitrogen (1.28 ± 0.05% DW) and starch (6.42 ± 0.50 DW %) content. Halodule uninervis formed large, clustered patches of dense biomass across the pasture and thus nitrogen and starch were concentrated where H. uninervis was prevalent. This seagrass meadow appears to be utilised well below its potential dugong carrying capacity. The survey and analytical techniques used enabled rapid, economical and accurate quantification and characterisation of seagrass habitat at scales relevant to a large forager.

  13. Interoperability challenges for the Sustainable Management of seagrass meadows (Invited)

    NASA Astrophysics Data System (ADS)

    Nativi, S.; Pastres, R.; Bigagli, L.; Venier, C.; Zucchetta, M.; Santoro, M.

    2013-12-01

    Seagrass meadows (marine angiosperm plants) occupy less than 0.2% of the global ocean surface, annually store about 10-18% of the so-called 'Blue Carbon', i.e. the Carbon stored in coastal vegetated areas. Recent literature estimates that the flux to the long-term carbon sink in seagrasses represents 10-20% of seagrasses global average production. Such figures can be translated into economic benefits, taking into account that a ton of carbon dioxide in Europe is paid at around 15 € in the carbon market. This means that the organic carbon retained in seagrass sediments in the Mediterranean is worth 138 - 1128 billion €, which represents 6-23 € per square meter. This is 9-35 times more than one square meter of tropical forest soil (0.66 € per square meter), or 5-17 times when considering both the above and the belowground compartments in tropical forests. According the most conservative estimations, about 10% of the Mediterranean meadows have been lost during the last century. In the framework of the GEOSS (Global Earth Observation System of Systems) initiative, the MEDINA project (funded by the European Commission and coordinated by the University of Ca'Foscari in Venice) prepared a showcase as part of the GEOSS Architecture Interoperability Pilot -phase 6 (AIP-6). This showcase aims at providing a tool for the sustainable management of seagrass meadows along the Mediterranean coastline. The application is based on an interoperability framework providing a set of brokerage services to easily ingest and run a Habitat Suitability model (a model predicting the probability a given site to provide a suitable habitat for the development of seagrass meadow and the average coverage expected). The presentation discusses such a framework explaining how the input data is discovered, accessed and processed to ingest the model (developed in the MEDINA project). Furthermore, the brokerage framework provides the necessary services to run the model and visualize results

  14. Rhizosphere Microbiomes of European Seagrasses Are Selected by the Plant, But Are Not Species Specific

    PubMed Central

    Cúcio, Catarina; Engelen, Aschwin H.; Costa, Rodrigo; Muyzer, Gerard

    2016-01-01

    Seagrasses are marine flowering plants growing in soft-body sediments of intertidal and shallow sub-tidal zones. They play an important role in coastal ecosystems by stabilizing sediments, providing food and shelter for animals, and recycling nutrients. Like other plants, seagrasses live intimately with both beneficial and unfavorable microorganisms. Although much is known about the microbiomes of terrestrial plants, little is known about the microbiomes of seagrasses. Here we present the results of a detailed study on the rhizosphere microbiome of seagrass species across the North-eastern Atlantic Ocean: Zostera marina, Zostera noltii, and Cymodocea nodosa. High-resolution amplicon sequencing of 16S rRNA genes showed that the rhizobiomes were significantly different from the bacterial communities of surrounding bulk sediment and seawater. Although we found no significant differences between the rhizobiomes of different seagrass species within the same region, those of seagrasses in different geographical locations differed strongly. These results strongly suggest that the seagrass rhizobiomes are shaped by plant metabolism, but not coevolved with their host. The core rhizobiome of seagrasses includes mostly bacteria involved in the sulfur cycle, thereby highlighting the importance of sulfur-related processes in seagrass ecosystems. PMID:27065991

  15. Rhizosphere Microbiomes of European + Seagrasses Are Selected by the Plant, But Are Not Species Specific.

    PubMed

    Cúcio, Catarina; Engelen, Aschwin H; Costa, Rodrigo; Muyzer, Gerard

    2016-01-01

    Seagrasses are marine flowering plants growing in soft-body sediments of intertidal and shallow sub-tidal zones. They play an important role in coastal ecosystems by stabilizing sediments, providing food and shelter for animals, and recycling nutrients. Like other plants, seagrasses live intimately with both beneficial and unfavorable microorganisms. Although much is known about the microbiomes of terrestrial plants, little is known about the microbiomes of seagrasses. Here we present the results of a detailed study on the rhizosphere microbiome of seagrass species across the North-eastern Atlantic Ocean: Zostera marina, Zostera noltii, and Cymodocea nodosa. High-resolution amplicon sequencing of 16S rRNA genes showed that the rhizobiomes were significantly different from the bacterial communities of surrounding bulk sediment and seawater. Although we found no significant differences between the rhizobiomes of different seagrass species within the same region, those of seagrasses in different geographical locations differed strongly. These results strongly suggest that the seagrass rhizobiomes are shaped by plant metabolism, but not coevolved with their host. The core rhizobiome of seagrasses includes mostly bacteria involved in the sulfur cycle, thereby highlighting the importance of sulfur-related processes in seagrass ecosystems.

  16. Seagrass Restoration Enhances “Blue Carbon” Sequestration in Coastal Waters

    PubMed Central

    Greiner, Jill T.; McGlathery, Karen J.; Gunnell, John; McKee, Brent A.

    2013-01-01

    Seagrass meadows are highly productive habitats that provide important ecosystem services in the coastal zone, including carbon and nutrient sequestration. Organic carbon in seagrass sediment, known as “blue carbon,” accumulates from both in situ production and sedimentation of particulate carbon from the water column. Using a large-scale restoration (>1700 ha) in the Virginia coastal bays as a model system, we evaluated the role of seagrass, Zosteramarina, restoration in carbon storage in sediments of shallow coastal ecosystems. Sediments of replicate seagrass meadows representing different age treatments (as time since seeding: 0, 4, and 10 years), were analyzed for % carbon, % nitrogen, bulk density, organic matter content, and 210Pb for dating at 1-cm increments to a depth of 10 cm. Sediment nutrient and organic content, and carbon accumulation rates were higher in 10-year seagrass meadows relative to 4-year and bare sediment. These differences were consistent with higher shoot density in the older meadow. Carbon accumulation rates determined for the 10-year restored seagrass meadows were 36.68 g C m-2 yr-1. Within 12 years of seeding, the restored seagrass meadows are expected to accumulate carbon at a rate that is comparable to measured ranges in natural seagrass meadows. This the first study to provide evidence of the potential of seagrass habitat restoration to enhance carbon sequestration in the coastal zone. PMID:23967303

  17. SMALL-SCALE HETEROGENEITY IN THE GEOCHEMISTRY OF SEAGRASS VEGETATED AND NON-VEGETATIVE SEDIMENTS: CAUSES AND CONSEQUENCES

    EPA Science Inventory

    In addition to nutrient and light availability, sedimentary biogeochemical processes can play an essential role in seagrass productivity. Previous investigations of the interactions between seagrasses and their underlying sediments have failed to clearly identify the spatio-tempo...

  18. Resource utilization and trophic position of nematodes and harpacticoid copepods in and adjacent to Zostera noltii beds

    NASA Astrophysics Data System (ADS)

    Vafeiadou, A.-M.; Materatski, P.; Adão, H.; De Troch, M.; Moens, T.

    2014-01-01

    This study examines the resource use and trophic position of nematodes and harpacticoid copepods at the genus/species level in an estuarine food web in Zostera noltii beds and in adjacent bare sediments, using the natural abundance of stable carbon and nitrogen isotopes. Microphytobenthos is among the main resources of most taxa, but seagrass-associated resources (i.e. seagrass detritus and epiphytes) also contribute to meiobenthos nutrition, with seagrass detritus being available also in deeper sediments and in unvegetated patches close to seagrass beds. A predominant dependence on chemoautotrophic bacteria was demonstrated for the nematode genus Terschellingia and the copepod family Cletodidae. A predatory feeding mode is illustrated for Paracomesoma and other Comesomatidae, which were previously considered first-level consumers (deposit feeders) according to their buccal morphology. The considerable variation found in both resource use and trophic level among nematode genera from the same feeding type, and even among congeneric nematode species, shows that interpretation of nematode feeding ecology based purely on mouth morphology should be avoided.

  19. Photosynthetic carbon reduction by seagrasses exposed to ultraviolet A radiation

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The seagrasses Halophila engelmannii, Halodule wrightii, and Syringodium filiforme were examined for their intrinsic sensitivity to ultraviolet-A-UV-A and ultraviolet-B-UV-B radiation. The effect of UV-A on photosynthetically active radiation (PAR) was also determined. Ultraviolet-A and ultraviolet-B were studied with emphasis on the greater respective environmental consequence in terms of seagrass distribution and abundance. Results indicate that an intrinsic sensitivity to UV-A alone is apparent only in Halophila, while net photosynthesis in Halodule and Syringodium seems unaffected by the level of UV-A provided. The sensitivity of Halophila to UV-A in the absense of (PAR) indicates that the photosynthetic reaction does not need to be in operation for damage to occur. Other significant results are reported.

  20. The perilous state of seagrass in the British Isles

    PubMed Central

    Jones, Benjamin L.; Unsworth, Richard K. F.

    2016-01-01

    Seagrass ecosystems face widespread threat from reduced water quality, coastal development and poor land use. In recent decades, their distribution has declined rapidly, and in the British Isles, this loss is thought to have been extensive. Given increasing knowledge of how these ecosystems support fisheries production, the understanding of their potential rapid loss, and the difficulty in restoring them, it is vital we develop an understanding of the risks they are under, so that management actions can be developed accordingly. Developing an understanding of their environmental status and condition is therefore critical to their long-term management. This study provided, to our knowledge, the first examination of the environmental health of seagrass meadows around the British Isles. This study used a bioindicator approach and involved collecting data on seagrass density and morphology alongside analysis of leaf biochemistry. Our study provides, to the best of our knowledge, the first strong quantitative evidence that seagrass meadows of the British Isles are mostly in poor condition in comparison with global averages, with tissue nitrogen levels 75% higher than global values. Such poor status places their long-term resilience in doubt. Elemental nutrient concentrations and morphological change suggest conditions of excess nitrogen and probable low light, placing many of the meadows sampled in a perilous state, although others, situated away from human populations were perceived to be healthy. Although some sites were of a high environmental health, all sites were considered at risk from anthropogenic impacts, particularly poor water quality and boating-based disturbances. The findings of this study provide a warning of the need to take action, with respect to water quality and disturbance, to prevent the further loss and degradation of these systems across the British Isles. PMID:26909188

  1. Unravelling complexity in seagrass systems for management: Australia as a microcosm.

    PubMed

    Kilminster, Kieryn; McMahon, Kathryn; Waycott, Michelle; Kendrick, Gary A; Scanes, Peter; McKenzie, Len; O'Brien, Katherine R; Lyons, Mitchell; Ferguson, Angus; Maxwell, Paul; Glasby, Tim; Udy, James

    2015-11-15

    Environmental decision-making applies transdisciplinary knowledge to deliver optimal outcomes. Here we synthesise various aspects of seagrass ecology to aid environmental decision-making, management and policy. Managers often mediate conflicting values and opinions held by different stakeholders. Critical to this role is understanding the drivers for change, effects of management actions and societal benefits. We use the diversity of seagrass habitats in Australia to demonstrate that knowledge from numerous fields is required to understand seagrass condition and resilience. Managers are often time poor and need access to synthesised assessments, commonly referred to as narratives. However, there is no single narrative for management of seagrass habitats in Australia, due to the diversity of seagrass meadows and dominant pressures. To assist the manager, we developed a classification structure based on attributes of seagrass life history, habitat and meadow form. Seagrass communities are formed from species whose life history strategies can be described as colonising, opportunistic or persistent. They occupy habitats defined by the range and variability of their abiotic environment. This results in seagrass meadows that are either transitory or enduring. Transitory meadows may come and go and able to re-establish from complete loss through sexual reproduction. Enduring meadows may fluctuate in biomass but maintain a presence by resisting pressures across multiple scales. This contrast reflects the interaction between the spatial and temporal aspects of species life history and habitat variability. Most management and monitoring strategies in place today favour enduring seagrasses. We adopt a functional classification of seagrass habitats based on modes of resilience to inform management for all seagrass communities. These concepts have world-wide relevance as the Australian case-studies have many analogues throughout the world. Additionally, the approach used to

  2. Seagrass feeding choices and digestive strategies of the herbivorous fish Sarpa salpa.

    PubMed

    Goldenberg, S U; Erzini, K

    2014-05-01

    This is the first study investigating the plant-herbivore interaction between Sarpa salpa, which has overgrazed seagrass transplants in Portugal, and the seagrasses Cymodocea nodosa, Zostera marina and Zostera noltii, which have been considered for restoration. When offered the choice between the three seagrasses in outdoor tanks, adult S. salpa clearly preferred Z. noltii. Testing the seagrasses separately, mean ± s.d. feeding rates ranged from 21 ± 11 g seagrass fresh mass kg⁻¹ fish mass day⁻¹ for Z. marina to 32 ± 9 g seagrass fresh mass kg⁻¹ fish mass day⁻¹ for C. nodosa and 40 ± 11 g seagrass fresh mass kg⁻¹ fish mass day⁻¹ for Z. noltii (temperature = 16° C). Food-processing rate in S. salpa did not differ between seagrasses, and there was no evidence of a regulation of processing rate according to food intake. Seagrasses differed substantially in nitrogen content and C:N, with C. nodosa containing the highest nitrogen content and lowest C:N (2·5 ± 0·1% and 14·0 ± 1·0), followed by Z. noltii (2·1 ± 0·1% and 17·0 ± 1·0) and Z. marina (1·4 ± 0·1% and 26·0 ± 2·0). Food-processing rate in S. salpa and the nutritional value of the seagrasses were not correlated with the observed feeding preference and rate. The study suggests that C. nodosa and Z. marina are less at risk of overgrazing by S. salpa and might thus be preferable to Z. noltii for seagrass restoration in areas with noticeable abundances of this fish.

  3. Genetic diversity of seagrass seeds influences seedling morphology and biomass.

    PubMed

    Randall Hughes, A; Hanley, Torrance C; Schenck, Forest R; Hays, Cynthia G

    2016-12-01

    Genetic diversity can influence ecological processes throughout ontogeny, yet whether diversity at early life history stages is important in long-lived taxa with overlapping generations is unclear. Seagrass systems provide some of the best evidence for the ecological effects of genetic diversity among adult shoots, but we do not know if the genetic diversity of seeds and seedlings also influences seagrass ecology. We tested the effects of seagrass (Zostera marina) seed diversity and relatedness on germination success, seedling morphology, and seedling production by comparing experimental assemblages of seeds collected from single reproductive shoots ("monocultures") to assemblages of seeds collected from multiple reproductive shoots ("polycultures"). There was no difference in seedling emergence, yet seedlings from polycultures had larger shoots above and below ground than seedlings from monocultures at the end of the 1-yr experiment. Genetic relatedness of the seedlings predicted some aspects of shoot morphology, with more leaves and longer roots and shoots at intermediate levels of relatedness, regardless of seed diversity. Our results suggest that studies of only adult stages may underestimate the importance of genetic diversity if the benefits at early life history stages continue to accrue throughout the life cycle.

  4. Middle Eocene seagrass facies from Apennine carbonate platforms (Italy)

    NASA Astrophysics Data System (ADS)

    Tomassetti, Laura; Benedetti, Andrea; Brandano, Marco

    2016-04-01

    Two stratigraphic sections located in the Latium-Abruzzi (Monte Porchio, Central Apennines, Central Italy) and in the Apulian carbonate platform (S. Cesarea-Torre Tiggiano, Salento, Southern Italy) were measured and sampled to document the sedimentological characteristic and the faunistic assemblages of Middle Eocene seagrass deposits. The faunistic assemblages are dominated by porcellaneous foraminifera Orbitolites, Alveolina, Idalina, Spiroloculina, Quinqueloculina, Triloculina and abundant hooked-shaped gypsinids, associated with hooked red algae and green algae Halimeda. Fabiania, rotaliids and textulariids as well as nummulitids are subordinated. The samples were assigned to Lutetian (SBZ13-16) according to the occurrence of Nummulites cf. lehneri, Alveolina ex. gr. elliptica, Idalina berthelini, Orbitolites complanatus, Slovenites decastroi and Medocia blayensis. At Santa Cesarea reticulate nummulites occur in association with Alveolina spp. and Halkyardia minima marking the lower Bartonian (SBZ17). Three main facies associations have been recognised: I) larger porcellaneous foraminiferal grainstones with orbitolitids and alveolinids deposited into high-energy shallow-water settings influenced by wave processes that reworked the sediments associated with a seagrass; II) grainstone to packstone with small porcellaneous foraminifera and abundant permanently-attached gypsinids deposited in a more protected (e.g., small embayment) in situ vegetated environment; III) bioclastic packstone with parautochthonous material reworked from the seagrass by rip currents and accumulated into rip channels in a slightly deeper environment. The biotic assemblages suggest that the depositional environment is consistent with tropical to subtropical vegetated environments within oligotrophic conditions.

  5. Sulfide Intrusion and Detoxification in the Seagrass Zostera marina.

    PubMed

    Hasler-Sheetal, Harald; Holmer, Marianne

    2015-01-01

    Gaseous sulfide intrusion into seagrasses growing in sulfidic sediments causes little or no harm to the plant, indicating the presence of an unknown sulfide tolerance or detoxification mechanism. We assessed such mechanism in the seagrass Zostera marina in the laboratory and in the field with scanning electron microscopy coupled to energy dispersive X-ray spectroscopy, chromatographic and spectrophotometric methods, and stable isotope tracing coupled with a mass balance of sulfur compounds. We found that Z. marina detoxified gaseous sediment-derived sulfide through incorporation and that most of the detoxification occurred in underground tissues, where sulfide intrusion was greatest. Elemental sulfur was a major detoxification compound, precipitating on the inner wall of the aerenchyma of underground tissues. Sulfide was metabolized into thiols and entered the plant sulfur metabolism as well as being stored as sulfate throughout the plant. We conclude that avoidance of sulfide exposure by reoxidation of sulfide in the rhizosphere or aerenchyma and tolerance of sulfide intrusion by incorporation of sulfur in the plant are likely major survival strategies of seagrasses in sulfidic sediments.

  6. Evaluation of a Single-Beam Sonar System to Map Seagrass at Two Sites in Northern Puget Sound, Washington

    USGS Publications Warehouse

    Stevens, Andrew W.; Lacy, Jessica R.; Finlayson, David P.; Gelfenbaum, Guy

    2008-01-01

    Seagrass at two sites in northern Puget Sound, Possession Point and nearby Browns Bay, was mapped using both a single-beam sonar and underwater video camera. The acoustic and underwater video data were compared to evaluate the accuracy of acoustic estimates of seagrass cover. The accuracy of the acoustic method was calculated for three classifications of seagrass observed in underwater video: bare (no seagrass), patchy seagrass, and continuous seagrass. Acoustic and underwater video methods agreed in 92 percent and 74 percent of observations made in bare and continuous areas, respectively. However, in patchy seagrass, the agreement between acoustic and underwater video was poor (43 percent). The poor agreement between the two methods in areas with patchy seagrass is likely because the two instruments were not precisely colocated. The distribution of seagrass at the two sites differed both in overall percent vegetated and in the distribution of percent cover versus depth. On the basis of acoustic data, seagrass inhabited 0.29 km2 (19 percent of total area) at Possession Point and 0.043 km2 (5 percent of total area) at the Browns Bay study site. The depth distribution at the two sites was markedly different. Whereas the majority of seagrass at Possession Point occurred between -0.5 and -1.5 m MLLW, most seagrass at Browns Bay occurred at a greater depth, between -2.25 and -3.5 m MLLW. Further investigation of the anthropogenic and natural factors causing these differences in distribution is needed.

  7. Modelling benthic macrofauna and seagrass distribution patterns in a North Sea tidal basin in response to 2050 climatic and environmental scenarios

    NASA Astrophysics Data System (ADS)

    Singer, Anja; Millat, Gerald; Staneva, Joanna; Kröncke, Ingrid

    2017-03-01

    Small-scale spatial distribution patterns of seven macrofauna species, seagrass beds and mixed mussel/oyster reefs were modelled for the Jade Bay (North Sea, Germany) in response to climatic and environmental scenarios (representing 2050). For the species distribution models four presence-absence modelling methods were merged within the ensemble forecasting platform 'biomod2'. The present spatial distribution (representing 2009) was modelled by statistically related species presences, true species absences and six high-resolution environmental grids. The future spatial distribution was then predicted in response to expected climate change-induced ongoing (1) sea-level rise and (2) water temperature increase. Between 2009 and 2050, the present and future prediction maps revealed a significant range gain for two macrofauna species (Macoma balthica, Tubificoides benedii), whereas the species' range sizes of five macrofauna species remained relatively stable across space and time. The predicted probability of occurrence (PO) of two macrofauna species (Cerastoderma edule, Scoloplos armiger) decreased significantly under the potential future habitat conditions. In addition, a clear seagrass bed extension (Zostera noltii) on the lower intertidal flats (mixed sediments) and a decrease in the PO of mixed Mytilus edulis/Crassostrea gigas reefs was predicted for 2050. Until the mid-21st century, our future climatic and environmental scenario revealed significant changes in the range sizes (gains-losses) and/or the PO (increases-decreases) for seven of the 10 modelled species at the study site.

  8. Photosynthetic activity buffers ocean acidification in seagrass meadows

    NASA Astrophysics Data System (ADS)

    Hendriks, I. E.; Olsen, Y. S.; Ramajo, L.; Basso, L.; Steckbauer, A.; Moore, T. S.; Howard, J.; Duarte, C. M.

    2013-07-01

    Macrophytes growing in shallow coastal zones characterized by intense metabolic activity have the capacity to modify pH within their canopy and beyond. We observed diel pH ranges is in shallow (5-12 m) seagrass (Posidonia oceanica) meadows from 0.06 pH units in September to 0.24 units in June. The carbonate system (pH, DIC, and aragonite saturation state (ΩAr) and O2 within the meadows displayed strong diel variability driven by primary productivity, and changes in chemistry were related to structural parameters of the meadow, in particular, the leaf surface area available for photosynthesis (LAI). LAI was positively correlated to mean and max pHNBS and max ΩAr. Oxygen production positively influenced the range and maximum pHNBS and the range of ΩAr. In June, vertical mixing (as Turbulent Kinetic Energy) influenced ΩAr, while in September there was no effect of hydrodynamics on the carbonate system within the canopy. ΩAr was positively correlated with the calcium carbonate load of the leaves, demonstrating a direct link between structural parameters, ΩAr and carbonate deposition. There was a direct relationship between ΩAr, influenced directly by meadow LAI, and CaCO3 content of the leaves. Therefore, calcifying organisms, e.g. epiphytes with carbonate skeletons, might benefit from the modification of the carbonate system by the meadow. The meadow might be capable of providing refugia for calcifiers by increasing pH and ΩAr through metabolic activity. There is, however, concern for the ability of seagrasses to provide this refugia function in the future. The predicted decline of seagrass meadows may alter the scope for alteration of pH within a seagrass meadow and in the water column above the meadow, particularly if shoot density and biomass decline, both strongly linked to LAI. Organisms associated with seagrass communities may therefore suffer from the loss of pH buffering capacity in degraded meadows.

  9. Abstraction and Consolidation

    ERIC Educational Resources Information Center

    Monaghan, John; Ozmantar, Mehmet Fatih

    2004-01-01

    What is involved in consolidating a new mathematical abstraction? This paper examines the work of one student who was working on a task designed to consolidate two recently constructed absolute function abstractions. The study adopts an activity theoretic model of abstraction in context. Selected protocol data are presented. The initial state of…

  10. Abstraction and Consolidation

    ERIC Educational Resources Information Center

    Monaghan, John; Ozmantar, Mehmet Fatih

    2006-01-01

    The framework for this paper is a recently developed theory of abstraction in context. The paper reports on data collected from one student working on tasks concerned with absolute value functions. It examines the relationship between mathematical constructions and abstractions. It argues that an abstraction is a consolidated construction that can…

  11. ENUMERATION, ISOLATION, AND CHARACTERIZATION OF ACETOGENIC BACTERIA ASSOCIATED WITH SEAGRASS ROOTS (POSTER SESSION)

    EPA Science Inventory

    Seagrasses are rooted in anoxic, sulfate-reducing sediments. However, the seagrass root is oxygenated during the daytime, becoming anoxic at night. Root thin sections hydridized with 33P-labeled probes revealed the presence of acetogenic and sulfate-reducing bacteria in the rhizo...

  12. ENUMERATION, ISOLATION, AND CHARACTERIZATION OF ACETOGENIC BACTERIA ASSOCIATED WITH SEAGRASS ROOTS

    EPA Science Inventory

    Seagrasses are rooted in anoxic, sulfate-reducing sediments. However, the seagrass root is oxygenated during the daytime, becoming anoxic at night. Root thin sections hydridized with 33P-labeled probes revealed the presence of acetogenic and sulfate-reducing bacteria in the rhizo...

  13. Learning about Coastal Trends: What Is the Story with Seagrass... and How Does It Affect Me?

    ERIC Educational Resources Information Center

    Ksiazek, Kelly; McGlathery, Karen; Reynolds, Laura; Schwarzschild, Arthur; Wilkerson, Carissa; Carruthers, Tim; Gurbisz, Cassie; Woerner, Joanna L.; Murray, Laura

    2009-01-01

    Flowering plants that live underwater in marine and estuarine habitats (seagrasses) are important because they support human food sources, such as crabs and fish, as well as endangered animals, such as turtles and manatees. Seagrasses are now known to be declining globally, largely as a result of increasing pressure from human populations living…

  14. A Monte Carlo study of the seagrass-induced depth bias in bathymetric lidar.

    PubMed

    Wang, Chi-Kuei; Philpot, William; Kim, Minsu; Lei, Hou-Meng

    2011-04-11

    A bathymetric lidar survey is the most cost efficient method of producing bathymetric maps in near shore areas where the ocean bottom is both highly variable and of greatest importance for shipping and recreation. So far, not much attention has been paid to the influence of bottom materials on the lidar signals. This study addresses this issue using a Monte Carlo modeling technique. The Monte Carlo simulation includes a plane parallel water body and a flat bottom with or without seagrass. The seagrass canopy structure is adopted from Zimmerman (2003). Both the surface of the seagrass leaves and the bottom are assumed to be Lambertian. Convolution with the lidar pulse function followed by the median operator is used to reduce the variance of the resultant lidar waveform. Two seagrass orientation arrangements are modeled: seagrass in still water with random leaf orientation and seagrass with a uniform orientation as would be expected when under the influence of a water current. For each case, two maximum canopy heights, 0.5 m and 1 m, three shoot densities, 100, 500, and 1000, and three bending angles, 5, 25, and 45 degrees, are considered. The seagrass is found to induce a depth bias that is proportional to an effective leaf area index (eLAI) and the contrast in reflectance between the seagrass and the bottom material.

  15. Development of threshold values for a seagrass epiphyte indicator of nutrient enrichment in coastal systems.

    EPA Science Inventory

    Epiphytes on seagrasses have been studied for more than 50 years, and proposed as an indicator of anthropogenic nutrient enrichment for over 30 years. Epiphytes have been correlated with seagrass declines, causally related to nutrient additions in both field and mesocosm experim...

  16. SEAGRASS EPIPHYTES AS A NUTRIENT STRESSOR INDICATOR: APPROACHES TOWARDS DEVELOPMENT OF THRESHOLD VALUES.

    EPA Science Inventory

    Epiphytes on seagrasses have been studied for more than 50 years, and proposed as an indicator of anthropogenic nutrient enrichment for over 30 years. Epiphytes have been correlated with seagrass declines, causally related to nutrient additions in both field and mesocosm experim...

  17. USE OF WAVE EXPOSURE TECHNIQUE FOR PREDICTING DISTRIBUTION AND ECOLOGICAL CHARACTERISTICS OF SEAGRASS ECOSYSTEMS

    EPA Science Inventory

    The development of seagrass patches and subsequently, the landscape that they define, is typically thought to be dependent on the phenotypic response of seagrass to environmental factors such as light/nutrients (Dennison et al. 1993), sedimentation (Harlin and Thorne-Miller 1981)...

  18. RELATIONSHIPS BETWEEN SEAGRASSES, BENTHIC MACROALGAE AND NUTRIENTS IN A PACIFIC NORTHWEST ESTUARY

    EPA Science Inventory

    Pacific Northwest estuaries are characterized by large tidal ranges (2-3 m) that routinely expose submerged aquatic vegetation (SAV) such as seagrass and benthic macroalgae. The dominant native seagrass in PNW estuaries is the eelgrass Zostera marina. However, in recent decades...

  19. Faunal communities and habitat characteristics of the Big Bend seagrass meadows, 2009-2010.

    EPA Science Inventory

    Seagrass meadows are important habitats that serve as nursery, feeding, and sheltering grounds for many marine species. In addition to the ecosystem functions and services they provide, seagrass habitats and associated fauna are commonly observed to have naturally high levels of...

  20. Losses and recovery of organic carbon from a seagrass ecosystem following disturbance.

    PubMed

    Macreadie, Peter I; Trevathan-Tackett, Stacey M; Skilbeck, Charles G; Sanderman, Jonathan; Curlevski, Nathalie; Jacobsen, Geraldine; Seymour, Justin R

    2015-10-22

    Seagrasses are among the Earth's most efficient and long-term carbon sinks, but coastal development threatens this capacity. We report new evidence that disturbance to seagrass ecosystems causes release of ancient carbon. In a seagrass ecosystem that had been disturbed 50 years ago, we found that soil carbon stocks declined by 72%, which, according to radiocarbon dating, had taken hundreds to thousands of years to accumulate. Disturbed soils harboured different benthic bacterial communities (according to 16S rRNA sequence analysis), with higher proportions of aerobic heterotrophs compared with undisturbed. Fingerprinting of the carbon (via stable isotopes) suggested that the contribution of autochthonous carbon (carbon produced through plant primary production) to the soil carbon pool was less in disturbed areas compared with seagrass and recovered areas. Seagrass areas that had recovered from disturbance had slightly lower (35%) carbon levels than undisturbed, but more than twice as much as the disturbed areas, which is encouraging for restoration efforts. Slow rates of seagrass recovery imply the need to transplant seagrass, rather than waiting for recovery via natural processes. This study empirically demonstrates that disturbance to seagrass ecosystems can cause release of ancient carbon, with potentially major global warming consequences.

  1. Habitat restoration: Early signs and extent of faunal recovery relative to seagrass recovery

    NASA Astrophysics Data System (ADS)

    McSkimming, Chloe; Connell, Sean D.; Russell, Bayden D.; Tanner, Jason E.

    2016-03-01

    The overall intent of restoration is often not only to restore the habitat per se, but to restore the ecosystem services it supplies, and particularly to encourage the return of fauna. Seagrass meadows act as habitat for some of the most diverse and abundant animal life, and as the global loss of seagrass continues, managers have sought to restore lost meadows. We tested how quickly the epifaunal richness, abundances and community composition of experimental restoration plots recovered to that in an adjacent natural seagrass meadow relative to the recovery of seagrass per se. Seagrass structure in the restoration plots took three years to become similar to a nearby natural meadow. The recovery of epifaunal richness and total abundance, however, occurred within one year. These results suggest that although recovering habitats may not be structurally similar to undisturbed habitats, they can support similar richness and abundances of epifauna, and thus have greater economic and social value than otherwise might have been expected. Nevertheless, whilst epifaunal richness and total abundance recovered prior to the recovery of seagrass structure, full recovery of seagrass was required before the composition and relative abundances of the epifaunal community matched that of the natural seagrass meadow.

  2. DYNAMICS OF A SUBTIDAL SEAGRASS LANDSCAPE: SEASONAL AND ANNUAL CHANGE IN RELATION TO WATER DEPTH

    EPA Science Inventory

    The spatial heterogeneity of a subtidal marine landscape and the areal extent of both monospecific and mixed patches of seagrass species were studied in Tampa Bay, FL. Specifically, we examined the temporal dynamics of seagrass distribution and its relationship to water depth an...

  3. Losses and recovery of organic carbon from a seagrass ecosystem following disturbance

    PubMed Central

    Macreadie, Peter I.; Trevathan-Tackett, Stacey M.; Skilbeck, Charles G.; Sanderman, Jonathan; Curlevski, Nathalie; Jacobsen, Geraldine; Seymour, Justin R.

    2015-01-01

    Seagrasses are among the Earth's most efficient and long-term carbon sinks, but coastal development threatens this capacity. We report new evidence that disturbance to seagrass ecosystems causes release of ancient carbon. In a seagrass ecosystem that had been disturbed 50 years ago, we found that soil carbon stocks declined by 72%, which, according to radiocarbon dating, had taken hundreds to thousands of years to accumulate. Disturbed soils harboured different benthic bacterial communities (according to 16S rRNA sequence analysis), with higher proportions of aerobic heterotrophs compared with undisturbed. Fingerprinting of the carbon (via stable isotopes) suggested that the contribution of autochthonous carbon (carbon produced through plant primary production) to the soil carbon pool was less in disturbed areas compared with seagrass and recovered areas. Seagrass areas that had recovered from disturbance had slightly lower (35%) carbon levels than undisturbed, but more than twice as much as the disturbed areas, which is encouraging for restoration efforts. Slow rates of seagrass recovery imply the need to transplant seagrass, rather than waiting for recovery via natural processes. This study empirically demonstrates that disturbance to seagrass ecosystems can cause release of ancient carbon, with potentially major global warming consequences. PMID:26490788

  4. Predicting habitat distribution to conserve seagrass threatened by sea level rise

    NASA Astrophysics Data System (ADS)

    Saunders, M. I.; Baldock, T.; Brown, C. J.; Callaghan, D. P.; Golshani, A.; Hamylton, S.; Hoegh-guldberg, O.; Leon, J. X.; Lovelock, C. E.; Lyons, M. B.; O'Brien, K.; Mumby, P.; Phinn, S. R.; Roelfsema, C. M.

    2013-12-01

    Sea level rise (SLR) over the 21st century will cause significant redistribution of valuable coastal habitats. Seagrasses form extensive and highly productive meadows in shallow coastal seas support high biodiversity, including economically valuable and threatened species. Predictive habitat models can inform local management actions that will be required to conserve seagrass faced with multiple stressors. We developed novel modelling approaches, based on extensive field data sets, to examine the effects of sea level rise and other stressors on two representative seagrass habitats in Australia. First, we modelled interactive effects of SLR, water clarity and adjacent land use on estuarine seagrass meadows in Moreton Bay, Southeast Queensland. The extent of suitable seagrass habitat was predicted to decline by 17% by 2100 due to SLR alone, but losses were predicted to be significantly reduced through improvements in water quality (Fig 1a) and by allowing space for seagrass migration with inundation. The rate of sedimentation in seagrass strongly affected the area of suitable habitat for seagrass in sea level rise scenarios (Fig 1b). Further research to understand spatial, temporal and environmental variability of sediment accretion in seagrass is required. Second, we modelled changes in wave energy distribution due to predicted SLR in a linked coral reef and seagrass ecosystem at Lizard Island, Great Barrier Reef. Scenarios where the water depth over the coral reef deepened due to SLR and minimal reef accretion, resulted in larger waves propagating shoreward, changing the existing hydrodynamic conditions sufficiently to reduce area of suitable habitat for seagrass. In a scenario where accretion of the coral reef was severely compromised (e.g. warming, acidification, overfishing), the probability of the presence of seagrass declined significantly. Management to maintain coral health will therefore also benefit seagrasses subject to SLR in reef environments. Further

  5. Abstraction and Problem Reformulation

    NASA Technical Reports Server (NTRS)

    Giunchiglia, Fausto

    1992-01-01

    In work done jointly with Toby Walsh, the author has provided a sound theoretical foundation to the process of reasoning with abstraction (GW90c, GWS9, GW9Ob, GW90a). The notion of abstraction formalized in this work can be informally described as: (property 1), the process of mapping a representation of a problem, called (following historical convention (Sac74)) the 'ground' representation, onto a new representation, called the 'abstract' representation, which, (property 2) helps deal with the problem in the original search space by preserving certain desirable properties and (property 3) is simpler to handle as it is constructed from the ground representation by "throwing away details". One desirable property preserved by an abstraction is provability; often there is a relationship between provability in the ground representation and provability in the abstract representation. Another can be deduction or, possibly inconsistency. By 'throwing away details' we usually mean that the problem is described in a language with a smaller search space (for instance a propositional language or a language without variables) in which formulae of the abstract representation are obtained from the formulae of the ground representation by the use of some terminating rewriting technique. Often we require that the use of abstraction results in more efficient .reasoning. However, it might simply increase the number of facts asserted (eg. by allowing, in practice, the exploration of deeper search spaces or by implementing some form of learning). Among all abstractions, three very important classes have been identified. They relate the set of facts provable in the ground space to those provable in the abstract space. We call: TI abstractions all those abstractions where the abstractions of all the provable facts of the ground space are provable in the abstract space; TD abstractions all those abstractions wllere the 'unabstractions' of all the provable facts of the abstract space are

  6. Seagrass ecosystems reduce exposure to bacterial pathogens of humans, fishes, and invertebrates.

    PubMed

    Lamb, Joleah B; van de Water, Jeroen A J M; Bourne, David G; Altier, Craig; Hein, Margaux Y; Fiorenza, Evan A; Abu, Nur; Jompa, Jamaluddin; Harvell, C Drew

    2017-02-17

    Plants are important in urban environments for removing pathogens and improving water quality. Seagrass meadows are the most widespread coastal ecosystem on the planet. Although these plants are known to be associated with natural biocide production, they have not been evaluated for their ability to remove microbiological contamination. Using amplicon sequencing of the 16S ribosomal RNA gene, we found that when seagrass meadows are present, there was a 50% reduction in the relative abundance of potential bacterial pathogens capable of causing disease in humans and marine organisms. Moreover, field surveys of more than 8000 reef-building corals located adjacent to seagrass meadows showed twofold reductions in disease levels compared to corals at paired sites without adjacent seagrass meadows. These results highlight the importance of seagrass ecosystems to the health of humans and other organisms.

  7. Seagrass importance for a small-scale fishery in the tropics: the need for seascape management.

    PubMed

    de la Torre-Castro, Maricela; Di Carlo, Giuseppe; Jiddawi, Narriman S

    2014-06-30

    Small-scale fisheries (SSF) in tropical seascapes (mosaics of interconnected mangroves, seagrasses and corals) are crucial for food and income. However, management is directed mostly to corals and mangroves. This research analyzes the importance of seagrasses compared to adjacent ecosystems in Chwaka Bay, Zanzibar, Tanzania. Using fish landings; the study investigated: location of fishing effort, fish production (biomass and species), and monetary benefits (aggregated value and per capita income). Seagrasses were the most visited grounds providing highest community benefits. Per capita benefits were equivalent to those from corals and mangroves. All three habitats provided income just above extreme poverty levels; however catches from seagrass appeared more stable. Seagrass are key ecosystems supporting SSF and protection and management are urgently needed. Adoption of a seascape approach considering all ecosystems underpinning SSF and the social aspects of fishing and a shift in emphasis from pure conservation to sustainable resource management would be desirable.

  8. Abstraction in mathematics.

    PubMed Central

    Ferrari, Pier Luigi

    2003-01-01

    Some current interpretations of abstraction in mathematical settings are examined from different perspectives, including history and learning. It is argued that abstraction is a complex concept and that it cannot be reduced to generalization or decontextualization only. In particular, the links between abstraction processes and the emergence of new objects are shown. The role that representations have in abstraction is discussed, taking into account both the historical and the educational perspectives. As languages play a major role in mathematics, some ideas from functional linguistics are applied to explain to what extent mathematical notations are to be considered abstract. Finally, abstraction is examined from the perspective of mathematics education, to show that the teaching ideas resulting from one-dimensional interpretations of abstraction have proved utterly unsuccessful. PMID:12903658

  9. Seagrass-Watch: Engaging Torres Strait Islanders in marine habitat monitoring

    NASA Astrophysics Data System (ADS)

    Mellors, Jane E.; McKenzie, Len J.; Coles, Robert G.

    2008-09-01

    Involvement in scientifically structured habitat monitoring is a relatively new concept to the peoples of Torres Strait. The approach we used was to focus on awareness, and to build the capacity of groups to participate using Seagrass-Watch as the vehicle to provide education and training in monitoring marine ecosystems. The project successfully delivered quality scientifically rigorous baseline information on the seasonality of seagrasses in the Torres Strait—a first for this region. Eight seagrass species were identified across the monitoring sites. Seagrass cover varied within and between years. Preliminary evidence indicated that drivers for seagrass variability were climate related. Generally, seagrass abundance increased during the north-west monsoon ( Kuki), possibly a consequence of elevated nutrients, lower tidal exposure times, less wind, and higher air temperatures. Low seagrass abundance coincided with the presence of greater winds and longer periods of exposure at low tides during the south-east trade wind season ( Sager). No seasonal patterns were apparent when frequency of disturbance from high sedimentation and human impacts was high. Seagrass-Watch has been incorporated in to the Thursday Island High School's Marine Studies Unit ensuring continuity of monitoring. The students, teachers, and other interested individuals involved in Seagrass-Watch have mastered the necessary scientific procedures to monitor seagrass meadows, and developed skills in coordinating a monitoring program and skills in mentoring younger students. This has increased the participants' self-esteem and confidence, and given them an insight into how they may participate in the future management of their sea country.

  10. Quantitative estimate of commercial fish enhancement by seagrass habitat in southern Australia

    NASA Astrophysics Data System (ADS)

    Blandon, Abigayil; zu Ermgassen, Philine S. E.

    2014-03-01

    Seagrass provides many ecosystem services that are of considerable value to humans, including the provision of nursery habitat for commercial fish stock. Yet few studies have sought to quantify these benefits. As seagrass habitat continues to suffer a high rate of loss globally and with the growing emphasis on compensatory restoration, valuation of the ecosystem services associated with seagrass habitat is increasingly important. We undertook a meta-analysis of juvenile fish abundance at seagrass and control sites to derive a quantitative estimate of the enhancement of juvenile fish by seagrass habitats in southern Australia. Thirteen fish of commercial importance were identified as being recruitment enhanced in seagrass habitat, twelve of which were associated with sufficient life history data to allow for estimation of total biomass enhancement. We applied von Bertalanffy growth models and species-specific mortality rates to the determined values of juvenile enhancement to estimate the contribution of seagrass to commercial fish biomass. The identified species were enhanced in seagrass by 0.98 kg m-2 y-1, equivalent to ˜$A230,000 ha-1 y-1. These values represent the stock enhancement where all fish species are present, as opposed to realized catches. Having accounted for the time lag between fish recruiting to a seagrass site and entering the fishery and for a 3% annual discount rate, we find that seagrass restoration efforts costing $A10,000 ha-1 have a potential payback time of less than five years, and that restoration costing $A629,000 ha-1 can be justified on the basis of enhanced commercial fish recruitment where these twelve fish species are present.

  11. Seasonal composition and activity of sulfate-reducing prokaryotic communities in seagrass bed sediments

    EPA Science Inventory

    Sulfate-reducing prokaryotes (SRP) play a key role in the carbon and nutrient cycles of coastal marine, vegetated ecosystems, but the interactions of SRP communities with aquatic plants remain little studied. The abundance, activity, and community composition of SRP was studied i...

  12. Abstract and keywords.

    PubMed

    Peh, W C G; Ng, K H

    2008-09-01

    The abstract of a scientific paper represents a concise, accurate and factual mini-version of the paper contents. Abstract format may vary according to the individual journal. For original articles, a structured abstract usually consists of the following headings: aims (or objectives), materials and methods, results and conclusion. A few keywords that capture the main topics of the paper help indexing in the medical literature.

  13. A comparative analysis of benthic nematode assemblages from Zostera noltii beds before and after a major vegetation collapse

    NASA Astrophysics Data System (ADS)

    Materatski, Patrick; Vafeiadou, Anna-Maria; Ribeiro, Rui; Moens, Tom; Adão, Helena

    2015-12-01

    Benthic nematodes are widely regarded as very suitable organisms to monitor potential ecological effects of natural and anthropogenic disturbances in aquatic ecosystems. During 2008, the seagrass beds of Zostera noltii located in the Mira estuary (SW Portugal) disappeared completely. However, during 2009, slight symptoms of natural recovery were observed, a process which has since evolved intermittently. This study aims to investigate changes in patterns of nematode density, diversity, and trophic composition between two distinct habitat conditions: "before" the collapse of seagrass beds, and during the early recovery "after" the seagrass habitat loss, through the analysis of: i) temporal and spatial distribution patterns of nematode communities, and ii) the most important environmental variables influencing the nematode assemblages. The following hypotheses were tested: i) there would be differences in nematode assemblage density, biodiversity and trophic composition during both ecological conditions, "before" and "after"; and ii) there would be differences in nematode assemblage density, biodiversity and trophic composition at different sampling occasions during both ecological conditions. Nematode density and diversity were significantly different between the two ecological situations. A higher density was recorded before, but a higher diversity was evident after the collapse of Z. noltii. In spite of the disturbance caused by the seagrass habitat loss in the Mira estuary, the nematode trophic composition did not significantly differ between the before and after seagrass collapse situations. Despite the significant differences found among sampling occasions, a consistent temporal pattern was not evident. The response of nematode communities following this extreme event exhibited considerable resistance and resilience to the new environmental conditions.

  14. Food supply depends on seagrass meadows in the coral triangle

    NASA Astrophysics Data System (ADS)

    Unsworth, Richard K. F.; Hinder, Stephanie L.; Bodger, Owen G.; Cullen-Unsworth, Leanne C.

    2014-09-01

    The tropical seascape provides food and livelihoods to hundreds of millions of people, but the support of key habitats to this supply remains ill appreciated. For fisheries and conservation management actions to help promote resilient ecosystems, sustainable livelihoods, and food supply, knowledge is required about the habitats that help support fisheries productivity and the consequences of this for food security. This paper provides an interdisciplinary case study from the coral triangle of how seagrass meadows provide support for fisheries and local food security. We apply a triangulated approach that utilizes ecological, fisheries and market data combined with over 250 household interviews. Our research demonstrates that seagrass associated fauna in a coral triangle marine protected area support local food supply contributing at least 50% of the fish based food. This formed between 54% and 99% of daily protein intake in the area. Fishery catch was found to significantly vary with respect to village (p < 0.01) with habitat configuration a probable driver. Juvenile fish comprised 26% of the fishery catch and gear type significantly influenced this proportion (<0.05). Limited sustainability of fishery practices (high juvenile catch and a 51% decline in CPUE for the biggest fishery) and poor habitat management mean the security of this food supply has the potential to be undermined in the long-term. Findings of this study have implications for the management and assessment of fisheries throughout the tropical seascape. Our study provides an exemplar for why natural resource management should move beyond biodiversity and consider how conservation and local food security are interlinked processes that are not mutually exclusive. Seagrass meadows are under sustained threat worldwide, this study provides evidence of the need to conserve these not just to protect biodiversity but to protect food security.

  15. Monitoring coral reefs, seagrasses and mangroves in Costa Rica (CARICOMP).

    PubMed

    Cortés, Jorge; Fonseca, Ana C; Nivia-Ruiz, Jaime; Nielsen-Muñoz, Vanessa; Samper-Villarreal, Jimena; Salas, Eva; Martínez, Solciré; Zamora-Trejos, Priscilla

    2010-10-01

    The coral reefs, seagrasses and mangroves from the Costa Rican Caribbean coast have been monitored since 1999 using the CARICOMP protocol. Live coral cover at Meager Shoal reef bank (7 to 10 m depth) at the Parque Nacional Cahuita (National Park), increased from 13.3% in 1999, to 28.2% in 2003, but decreased during the next 5 years to around 17.5%. Algal cover increased significantly since 2003 from 36.6% to 61.3% in 2008. The density of Diadema antillarum oscillated between 2 and 7ind/m2, while Echinometra viridis decreased significantly from 20 to 0.6ind/m2. Compared to other CARICOMP sites, live coral cover, fish diversity and density, and sea urchin density were low, and algal cover was intermediate. The seagrass site, also in the Parque Nacional Cahuita, is dominated by Thalassia testudinum and showed an intermediate productivity (2.7 +/- 1.15 g/m2/d) and biomass (822.8 +/- 391.84 g/m2) compared to other CARICOMP sites. Coral reefs and seagrasses at the Parque Nacional Cahuita continue to be impacted by high sediment loads from terrestrial origin. The mangrove forest at Gandoca, within the Refugio Nacional de Vida Silvestre Gandoca-Manzanillo (National Wildlife Refuge), surrounds a lagoon and it is dominated by the red mangrove, Rhizophora mangle. Productivity and flower production peak was in July. Biomass (14 kg/m2) and density (9.0 +/- 0.58 trees/100 m2) in Gandoca were relatively low compared to other CARICOMP sites, while productivity in July in Costa Rica (4 g/m2/d) was intermediate, similar to most CARICOMP sites. This mangrove is expanding and has low human impact thus far. Management actions should be taken to protect and preserve these important coastal ecosystems.

  16. Packed Bed Reactor Experiment

    NASA Video Gallery

    The purpose of the Packed Bed Reactor Experiment in low gravity is to determine how a mixture of gas and liquid flows through a packed bed in reduced gravity. A packed bed consists of a metal pipe ...

  17. Partitioning loss rates of early juvenile blue crabs from seagrass habitats into mortality and emigration

    USGS Publications Warehouse

    Etherington, L.L.; Eggleston, D.B.; Stockhausen, W.T.

    2003-01-01

    in which crab loss from seagrass due to mortality was greater than losses due to emigration was not significantly different from 50%. Thus, mortality and emigration appear to contribute equally to juvenile loss in seagrass habitats. The difference in magnitude (absolute amount of loss) between mean emigration and mean mortality varied between size classes, such that differences between emigration and mortality were relatively small for J1-J2 crabs, but much larger for J3-J5 crabs. Further, mortality rates were density-dependent for J3-J5 juvenile stages but not for J1-J2 crabs, whereas emigration was inversely density-dependent among J3-J5 stages but not for J1-J2 instars. The co-dependency of mortality and emigration suggests that the loss term (emigration or mortality) which has the relatively stronger contribution to total loss may dictate the patterns of loss under different conditions. For older juveniles (J3-J5), emigration may only have a large impact on juvenile loss where densities are low, since the contribution of mortality appears to be much greater than emigration at high densities. The size-specific pattern of density-dependent mortality supports the notion of an ontogenetic habitat shift by early juvenile blue crabs from seagrass to unvegetated habitats, since larger individuals may experience increased mortality at high densities within seagrass beds. Qualitative comparisons between this study and a concurrent study of planktonic emigration of J1-J5 blue crabs (Blackmon and Eggleston, 2001) suggests that benthic emigration among J1-J2 blue crabs was greater than planktonic emigration; for J3-J5 stages benthic and planktonic emigration were nearly equal. This study demonstrates the potentially large role of emigration in recruitment processes and patterns of early juvenile blue crabs, and illustrates how juvenile size, juvenile density, and time of day can affect mortality and emigration rates as well as total loss and colonization. The components of

  18. Technical Abstracts, 1988

    SciTech Connect

    Kotowski, M.

    1989-05-01

    This document is a compilation of the abstracts from unclassified documents published by Mechanical Engineering at Lawrence Livermore National Laboratory (LLNL) during the calendar year 1988. Many abstracts summarize work completed and published in report form. These are UCRL-90,000 and 100,000 series documents, which include the full text of articles to be published in journals and of papers to be presented at meetings, and UCID reports, which are informal documents. Not all UCIDs contain abstracts: short summaries were generated when abstracts were not included. Technical Abstracts also provides brief descriptions of those documents assigned to the MISC (miscellaneous) category. These are generally viewgraphs or photographs presented at meetings. The abstracts cover the broad range of technologies within Mechanical Engineering and are grouped by the principal author's division. An eighth category is devoted to abstracts presented at the CUBE symposium sponsored jointly by LLNL, Los Alamos National Laboratory, and Sandia Laboratories. Within these areas, abstracts are listed numerically. An author index and title index are provided at the back of the book for cross referencing. The publications listed may be obtained by contacting LLNL's TID library or the National Technical Information Service, US Department of Commerce, 5285 Port Royal Road, Springfield, VA 22161. Further information may be obtained by contacting the author directly or the persons listed in the introduction of each subject area.

  19. Paper Abstract Animals

    ERIC Educational Resources Information Center

    Sutley, Jane

    2010-01-01

    Abstraction is, in effect, a simplification and reduction of shapes with an absence of detail designed to comprise the essence of the more naturalistic images being depicted. Without even intending to, young children consistently create interesting, and sometimes beautiful, abstract compositions. A child's creations, moreover, will always seem to…

  20. Leadership Abstracts, Volume 10.

    ERIC Educational Resources Information Center

    Milliron, Mark D., Ed.

    1997-01-01

    The abstracts in this series provide brief discussions of issues related to leadership, administration, professional development, technology, and education in community colleges. Volume 10 for 1997 contains the following 12 abstracts: (1) "On Community College Renewal" (Nathan L. Hodges and Mark D. Milliron); (2) "The Community College Niche in a…

  1. Is It Really Abstract?

    ERIC Educational Resources Information Center

    Kernan, Christine

    2011-01-01

    For this author, one of the most enjoyable aspects of teaching elementary art is the willingness of students to embrace the different styles of art introduced to them. In this article, she describes a project that allows upper-elementary students to learn about abstract art and the lives of some of the master abstract artists, implement the idea…

  2. Designing for Mathematical Abstraction

    ERIC Educational Resources Information Center

    Pratt, Dave; Noss, Richard

    2010-01-01

    Our focus is on the design of systems (pedagogical, technical, social) that encourage mathematical abstraction, a process we refer to as "designing for abstraction." In this paper, we draw on detailed design experiments from our research on children's understanding about chance and distribution to re-present this work as a case study in designing…

  3. Leadership Abstracts, 1996.

    ERIC Educational Resources Information Center

    Johnson, Larry, Ed.

    1996-01-01

    The abstracts in this series provide two-page discussions of issues related to leadership, administration, professional development, technology, and education in community colleges. Volume 9 for 1996 includes the following 12 abstracts: (1) "Tech-Prep + School-To-Work: Working Together To Foster Educational Reform," (Roderick F. Beaumont); (2)…

  4. Organizational Communication Abstracts--1975.

    ERIC Educational Resources Information Center

    Falcione, Raymond L.; And Others

    This document includes nearly 700 brief abstracts of works published in 1975 that are relevant to the field of organizational communication. The introduction presents a rationale for the project, a review of research methods developed by the authors for the preparation of abstracts, a statement of limitations as to the completeness of the coverage…

  5. Stability and resilience of seagrass meadows to seasonal and interannual dynamics and environmental stress

    NASA Astrophysics Data System (ADS)

    Carr, Joel A.; D'Odorico, Paolo; McGlathery, Karen J.; Wiberg, Patricia L.

    2012-03-01

    Shallow coastal bays provide habitat for diverse fish and invertebrate populations and are an important source of sediment for surrounding marshes. The sediment dynamics of these bays are strongly affected by seagrass meadows, which limit sediment resuspension, thereby providing a more favorable light environment for their own survival and growth. Due to this positive feedback between seagrass and light conditions, it has been suggested that bare sediment and seagrass meadows are potential alternate stable states of the benthos in shallow coastal bays. To investigate the stability and resilience of seagrass meadows subjected to variation in environmental conditions (e.g., light, temperature), a coupled model of vegetation-sediment-water flow interactions and vegetation growth was developed. The model was used to examine the effect of dynamically varying seasonal and interannual seagrass density on sediment resuspension, water column turbidity, and the subsequent light environment on hourly time steps and then run over decadal time scales. A daily growth model was designed to capture both belowground biomass and the growth and senescence of aboveground biomass structural components (e.g., leaves and stems). This allowed us to investigate how the annual and seasonal variability in shoot and leaf density within a meadow affects the strength of positive feedbacks between seagrass and their light environment. The model demonstrates both the emergence of bistable behavior from 1.6 to 1.8 m mean sea level due to the strength of the positive feedback, as well as the limited resilience of seagrass meadows within this bistable range.

  6. Acute and additive toxicity of ten photosystem-II herbicides to seagrass

    PubMed Central

    Wilkinson, Adam D.; Collier, Catherine J.; Flores, Florita; Negri, Andrew P.

    2015-01-01

    Photosystem II herbicides are transported to inshore marine waters, including those of the Great Barrier Reef, and are usually detected in complex mixtures. These herbicides inhibit photosynthesis, which can deplete energy reserves and reduce growth in seagrass, but the toxicity of some of these herbicides to seagrass is unknown and combined effects of multiple herbicides on seagrass has not been tested. Here we assessed the acute phytotoxicity of 10 PSII herbicides to the seagrass Halophila ovalis over 24 and/or 48 h. Individual herbicides exhibited a broad range of toxicities with inhibition of photosynthetic activity (∆F/Fm′) by 50% at concentrations ranging from 3.5 μg l−1 (ametryn) to 132 μg l−1 (fluometuron). We assessed potential additivity using the Concentration Addition model of joint action for binary mixtures of diuron and atrazine as well as complex mixtures of all 10 herbicides. The effects of both mixture types were largely additive, validating the application of additive effects models for calculating the risk posed by multiple PSII herbicides to seagrasses. This study extends seagrass ecotoxicological data to ametryn, metribuzin, bromacil, prometryn and fluometuron and demonstrates that low concentrations of PSII herbicide mixtures have the potential to impact ecologically relevant endpoints in seagrass, including ∆F/Fm′. PMID:26616444

  7. Acute and additive toxicity of ten photosystem-II herbicides to seagrass

    NASA Astrophysics Data System (ADS)

    Wilkinson, Adam D.; Collier, Catherine J.; Flores, Florita; Negri, Andrew P.

    2015-11-01

    Photosystem II herbicides are transported to inshore marine waters, including those of the Great Barrier Reef, and are usually detected in complex mixtures. These herbicides inhibit photosynthesis, which can deplete energy reserves and reduce growth in seagrass, but the toxicity of some of these herbicides to seagrass is unknown and combined effects of multiple herbicides on seagrass has not been tested. Here we assessed the acute phytotoxicity of 10 PSII herbicides to the seagrass Halophila ovalis over 24 and/or 48 h. Individual herbicides exhibited a broad range of toxicities with inhibition of photosynthetic activity (∆F/Fm‧) by 50% at concentrations ranging from 3.5 μg l-1 (ametryn) to 132 μg l-1 (fluometuron). We assessed potential additivity using the Concentration Addition model of joint action for binary mixtures of diuron and atrazine as well as complex mixtures of all 10 herbicides. The effects of both mixture types were largely additive, validating the application of additive effects models for calculating the risk posed by multiple PSII herbicides to seagrasses. This study extends seagrass ecotoxicological data to ametryn, metribuzin, bromacil, prometryn and fluometuron and demonstrates that low concentrations of PSII herbicide mixtures have the potential to impact ecologically relevant endpoints in seagrass, including ∆F/Fm‧.

  8. Acute and additive toxicity of ten photosystem-II herbicides to seagrass.

    PubMed

    Wilkinson, Adam D; Collier, Catherine J; Flores, Florita; Negri, Andrew P

    2015-11-30

    Photosystem II herbicides are transported to inshore marine waters, including those of the Great Barrier Reef, and are usually detected in complex mixtures. These herbicides inhibit photosynthesis, which can deplete energy reserves and reduce growth in seagrass, but the toxicity of some of these herbicides to seagrass is unknown and combined effects of multiple herbicides on seagrass has not been tested. Here we assessed the acute phytotoxicity of 10 PSII herbicides to the seagrass Halophila ovalis over 24 and/or 48 h. Individual herbicides exhibited a broad range of toxicities with inhibition of photosynthetic activity (∆F/F(m)') by 50% at concentrations ranging from 3.5 μg l(-1) (ametryn) to 132 μg l(-1) (fluometuron). We assessed potential additivity using the Concentration Addition model of joint action for binary mixtures of diuron and atrazine as well as complex mixtures of all 10 herbicides. The effects of both mixture types were largely additive, validating the application of additive effects models for calculating the risk posed by multiple PSII herbicides to seagrasses. This study extends seagrass ecotoxicological data to ametryn, metribuzin, bromacil, prometryn and fluometuron and demonstrates that low concentrations of PSII herbicide mixtures have the potential to impact ecologically relevant endpoints in seagrass, including ∆F/F(m)'.

  9. Solar radiation and tidal exposure as environmental drivers of Enhalus acoroides dominated seagrass meadows.

    PubMed

    Unsworth, Richard K F; Rasheed, Michael A; Chartrand, Kathryn M; Roelofs, Anthony J

    2012-01-01

    There is strong evidence of a global long-term decline in seagrass meadows that is widely attributed to anthropogenic activity. Yet in many regions, attributing these changes to actual activities is difficult, as there exists limited understanding of the natural processes that can influence these valuable ecosystem service providers. Being able to separate natural from anthropogenic causes of seagrass change is important for developing strategies that effectively mitigate and manage anthropogenic impacts on seagrass, and promote coastal ecosystems resilient to future environmental change. The present study investigated the influence of environmental and climate related factors on seagrass biomass in a large ≈250 ha meadow in tropical north east Australia. Annual monitoring of the intertidal Enhalus acoroides (L.f.) Royle seagrass meadow over eleven years revealed a declining trend in above-ground biomass (54% significant overall reduction from 2000 to 2010). Partial Least Squares Regression found this reduction to be significantly and negatively correlated with tidal exposure, and significantly and negatively correlated with the amount of solar radiation. This study documents how natural long-term tidal variability can influence long-term seagrass dynamics. Exposure to desiccation, high UV, and daytime temperature regimes are discussed as the likely mechanisms for the action of these factors in causing this decline. The results emphasise the importance of understanding and assessing natural environmentally-driven change when interpreting the results of seagrass monitoring programs.

  10. Abstract Datatypes in PVS

    NASA Technical Reports Server (NTRS)

    Owre, Sam; Shankar, Natarajan

    1997-01-01

    PVS (Prototype Verification System) is a general-purpose environment for developing specifications and proofs. This document deals primarily with the abstract datatype mechanism in PVS which generates theories containing axioms and definitions for a class of recursive datatypes. The concepts underlying the abstract datatype mechanism are illustrated using ordered binary trees as an example. Binary trees are described by a PVS abstract datatype that is parametric in its value type. The type of ordered binary trees is then presented as a subtype of binary trees where the ordering relation is also taken as a parameter. We define the operations of inserting an element into, and searching for an element in an ordered binary tree; the bulk of the report is devoted to PVS proofs of some useful properties of these operations. These proofs illustrate various approaches to proving properties of abstract datatype operations. They also describe the built-in capabilities of the PVS proof checker for simplifying abstract datatype expressions.

  11. Development of a DNA Barcoding System for Seagrasses: Successful but Not Simple

    PubMed Central

    Lucas, Christina; Thangaradjou, Thirunavakkarasu; Papenbrock, Jutta

    2012-01-01

    Seagrasses, a unique group of submerged flowering plants, profoundly influence the physical, chemical and biological environments of coastal waters through their high primary productivity and nutrient recycling ability. They provide habitat for aquatic life, alter water flow, stabilize the ground and mitigate the impact of nutrient pollution. at the coast region. Although on a global scale seagrasses represent less than 0.1% of the angiosperm taxa, the taxonomical ambiguity in delineating seagrass species is high. Thus, the taxonomy of several genera is unsolved. While seagrasses are capable of performing both, sexual and asexual reproduction, vegetative reproduction is common and sexual progenies are always short lived and epimeral in nature. This makes species differentiation often difficult, especially for non-taxonomists since the flower as a distinct morphological trait is missing. Our goal is to develop a DNA barcoding system assisting also non-taxonomists to identify regional seagrass species. The results will be corroborated by publicly available sequence data. The main focus is on the 14 described seagrass species of India, supplemented with seagrasses from temperate regions. According to the recommendations of the Consortium for the Barcoding of Life (CBOL) rbcL and matK were used in this study. After optimization of the DNA extraction method from preserved seagrass material, the respective sequences were amplified from all species analyzed. Tree- and character-based approaches demonstrate that the rbcL sequence fragment is capable of resolving up to family and genus level. Only matK sequences were reliable in resolving species and partially the ecotype level. Additionally, a plastidic gene spacer was included in the analysis to confirm the identification level. Although the analysis of these three loci solved several nodes, a few complexes remained unsolved, even when constructing a combined tree for all three loci. Our approaches contribute to the

  12. Species composition and biomasses of fishes in tropical seagrasses at Groote Eylandt, northern Australia

    NASA Astrophysics Data System (ADS)

    Blaber, S. J. M.; Brewer, D. T.; Salini, J. P.; Kerr, J. D.; Conacher, C.

    1992-12-01

    The species composition and biomasses of fishes in the tropical seagrasses of Groote Eylandt, northern Australia, were studied in 1989 and 1990. A total of 156 species was recorded. Tall dense seagrass, short seagrass and control (no seagrass) sites in different depths were compared. Shallow (<1 m) sites were dominated by small resident species and juveniles of non-resident species, while deeper waters (to 7 m) were dominated by larger species. Species composition was not significantly different between sites, but species diversity ( H) and evenness ( E) were higher in non-vegetated areas. In slightly deeper water (<2 m) species composition was different between habitats and species diversity was highest in tall seagrass and least in open areas. Most species were more abundant in tall seagrass and least abundant in open areas. Most of the larger fishes, including 11 species of sharks, are piscivores, and most move into shallow sea-grass areas at night, irrespective of tide height. Only five species showed abundance patterns related to tide height and there were no significant seasonal patterns of abundance in any of the communities. The biomasses for all sites and sampling methods were mostly from 1 to 2 g m -2, which is low relative to other inshore tropical areas. The possible causes—the characteristics of adjacent habitats (coral reefs and mangroves) and the role of seagrasses in the life cycle of fishes are discussed. It is suggested that habitat structure is a major determinant of the species composition of fish in tropical seagrass areas, primarily because it affects food availability, both for small residents and juveniles, and for visiting predators.

  13. Seagrass response to CO₂ contingent on epiphytic algae: indirect effects can overwhelm direct effects.

    PubMed

    Burnell, Owen W; Russell, Bayden D; Irving, Andrew D; Connell, Sean D

    2014-11-01

    Increased availability of dissolved CO2 in the ocean can enhance the productivity and growth of marine plants such as seagrasses and algae, but realised benefits may be contingent on additional conditions (e.g. light) that modify biotic interactions between these plant groups. The combined effects of future CO2 and differing light on the growth of seagrass and their algal epiphytes were tested by maintaining juvenile seagrasses Amphibolis antarctica under three different CO2 concentrations representing ambient, moderate future and high future forecasts (i.e. 390, 650 vs. 900 µl l(-1)) and two light levels representing low and high PAR (i.e. 43 vs. 167 µmol m(-2) s(-1)). Aboveground and belowground biomass, leaf growth, epiphyte cover, tissue chemistry and photosynthetic parameters of seagrasses were measured. At low light, there was a neutral to positive effect of elevated CO2 on seagrass biomass and growth; at high light, this effect of CO2 switched toward negative, as growth and biomass decreased at the highest CO2 level. These opposing responses to CO2 appeared to be closely linked to the overgrowth of seagrass by filamentous algal epiphytes when high light and CO2 were combined. Importantly, all seagrass plants maintained positive leaf growth throughout the experiment, indicating that growth was inhibited by some experimental conditions but not arrested entirely. Therefore, while greater light or elevated CO2 provided direct physiological benefits for seagrasses, such benefits were likely negated by overgrowth of epiphytic algae when greater light and CO2 were combined. This result demonstrates how indirect ecological effects from epiphytes can modify independent physiological predictions for seagrass associated with global change.

  14. A Meta-Analysis of Seaweed Impacts on Seagrasses: Generalities and Knowledge Gaps

    PubMed Central

    Thomsen, Mads S.; Wernberg, Thomas; Engelen, Aschwin H.; Tuya, Fernando; Vanderklift, Mat A.; Holmer, Marianne; McGlathery, Karen J.; Arenas, Francisco; Kotta, Jonne; Silliman, Brian R.

    2012-01-01

    Seagrasses are important habitat-formers and ecosystem engineers that are under threat from bloom-forming seaweeds. These seaweeds have been suggested to outcompete the seagrasses, particularly when facilitated by eutrophication, causing regime shifts where green meadows and clear waters are replaced with unstable sediments, turbid waters, hypoxia, and poor habitat conditions for fishes and invertebrates. Understanding the situations under which seaweeds impact seagrasses on local patch scales can help proactive management and prevent losses at greater scales. Here, we provide a quantitative review of available published manipulative experiments (all conducted at the patch-scale), to test which attributes of seaweeds and seagrasses (e.g., their abundances, sizes, morphology, taxonomy, attachment type, or origin) influence impacts. Weighted and unweighted meta-analyses (Hedges d metric) of 59 experiments showed generally high variability in attribute-impact relationships. Our main significant findings were that (a) abundant seaweeds had stronger negative impacts on seagrasses than sparse seaweeds, (b) unattached and epiphytic seaweeds had stronger impacts than ‘rooted’ seaweeds, and (c) small seagrass species were more susceptible than larger species. Findings (a) and (c) were rather intuitive. It was more surprising that ‘rooted’ seaweeds had comparatively small impacts, particularly given that this category included the infamous invasive Caulerpa species. This result may reflect that seaweed biomass and/or shading and metabolic by-products like anoxia and sulphides could be lower for rooted seaweeds. In conclusion, our results represent simple and robust first-order generalities about seaweed impacts on seagrasses. This review also documented a limited number of primary studies. We therefore identified major knowledge gaps that need to be addressed before general predictive models on seaweed-seagrass interactions can be build, in order to effectively

  15. Comparative analysis of expressed sequence tag (EST) libraries in the seagrass Zostera marina subjected to temperature stress.

    PubMed

    Reusch, Thorsten B H; Veron, Amelie S; Preuss, Christoph; Weiner, January; Wissler, Lothar; Beck, Alfred; Klages, Sven; Kube, Michael; Reinhardt, Richard; Bornberg-Bauer, Erich

    2008-01-01

    Global warming is associated with increasing stress and mortality on temperate seagrass beds, in particular during periods of high sea surface temperatures during summer months, adding to existing anthropogenic impacts, such as eutrophication and habitat destruction. We compare several expressed sequence tag (EST) in the ecologically important seagrass Zostera marina (eelgrass) to elucidate the molecular genetic basis of adaptation to environmental extremes. We compared the tentative unigene (TUG) frequencies of libraries derived from leaf and meristematic tissue from a control situation with two experimentally imposed temperature stress conditions and found that TUG composition is markedly different among these conditions (all P < 0.0001). Under heat stress, we find that 63 TUGs are differentially expressed (d.e.) at 25 degrees C compared with lower, no-stress condition temperatures (4 degrees C and 17 degrees C). Approximately one-third of d.e. eelgrass genes were characteristic for the stress response of the terrestrial plant model Arabidopsis thaliana. The changes in gene expression suggest complex photosynthetic adjustments among light-harvesting complexes, reaction center subunits of photosystem I and II, and components of the dark reaction. Heat shock encoding proteins and reactive oxygen scavengers also were identified, but their overall frequency was too low to perform statistical tests. In all conditions, the most abundant transcript (3-15%) was a putative metallothionein gene with unknown function. We also find evidence that heat stress may translate to enhanced infection by protists. A total of 210 TUGs contain one or more microsatellites as potential candidates for gene-linked genetic markers. Data are publicly available in a user-friendly database at http://www.uni-muenster.de/Evolution/ebb/Services/zostera .

  16. Redefining the trophic importance of seagrasses for fauna in tropical Indo-Pacific meadows

    NASA Astrophysics Data System (ADS)

    Vonk, Jan Arie; Christianen, Marjolijn J. A.; Stapel, Johan

    2008-09-01

    Fauna species living in seagrass meadows depend on different food sources, with seagrasses often being marginally important for higher trophic levels. To determine the food web of a mixed-species tropical seagrass meadow in Sulawesi, Indonesia, we analyzed the stable isotope ( δ13C and δ15N) signatures of primary producers, particulate organic matter (POM) and fauna species. In addition invertebrates, both infauna and macrobenthic, and fish densities were examined to identify the important species in the meadow. The aims of this study were to identify the main food sources of fauna species by comparing isotopic signatures of different primary producers and fauna, and to estimate qualitatively the importance of seagrass material in the food web. Phytoplankton and water column POM were the most depleted primary food sources for δ13C (range -23.1 to -19.6‰), but no fauna species depended only on these sources for carbon. Epiphytes and Sargassum sp. had intermediate δ13C values (-14.2 to -11.9‰). Sea urchins, gastropods and certain fish species were the main species assimilating this material. Seagrasses and sedimentary POM had the least depleted values (-11.5 to -5.7‰). Between the five seagrass species significant differences in δ13C were measured. The small species Halophila ovalis and Halodule uninervis were most depleted, the largest species Enhalus acoroides was least depleted, while Thalassia hemprichii and Cymodocea rotundata had intermediate values. Fourteen fauna species, accounting for ˜10% of the total fauna density, were shown to assimilate predominantly (>50%) seagrass material, either directly or indirectly by feeding on seagrass consumers. These species ranged from amphipods up to the benthic top predator Taeniura lymma. Besides these species, about half of the 55 fauna species analyzed had δ13C values higher than the least depleted non-seagrass source, indicating they depended at least partly for their food on seagrass material. This study

  17. AxIOM: Amphipod crustaceans from insular Posidonia oceanica seagrass meadows

    PubMed Central

    Heughebaert, André; Lepoint, Gilles

    2016-01-01

    Abstract Background The Neptune grass, Posidonia oceanica (L.) Delile, 1813, is the most widespread seagrass of the Mediterranean Sea. This foundation species forms large meadows that, through habitat and trophic services, act as biodiversity hotspots. In Neptune grass meadows, amphipod crustaceans are one of the dominant groups of vagile invertebrates, forming an abundant and diverse taxocenosis. They are key ecological components of the complex, pivotal, yet critically endangered Neptune grass ecosystems. Nevertheless, comprehensive qualitative and quantitative data about amphipod fauna found in Mediterranean Neptune grass meadows remain scarce, especially in insular locations. New information Here, we provide in-depth metadata about AxIOM, a sample-based dataset published on the GBIF portal. AxIOM is based on an extensive and spatially hierarchized sampling design with multiple years, seasons, day periods, and methods. Samples were taken along the coasts of Calvi Bay (Corsica, France) and of the Tavolara-Punta Coda Cavallo Marine Protected Area (Sardinia, Italy). In total, AxIOM contains 187 samples documenting occurrence (1775 records) and abundance (10720 specimens) of amphipod crustaceans belonging to 72 species spanning 29 families. The dataset is available at http://ipt.biodiversity.be/resource?r=axiom. PMID:27660521

  18. Detection of seagrass distribution changes from 1991 to 2006 in xincun bay, hainan, with satellite remote sensing.

    PubMed

    Yang, Dingtian; Yang, Chaoyu

    2009-01-01

    Seagrass distribution is a very important index for costal management and protection. Seagrass distribution changes can be used as indexes to analyze the reasons for the changes. In this paper, in situ hyperspectral observation and satellite images of QuickBird, CBERS (China Brazil Earth Resources Satellite data) and Landsat data were used to retrieve bio-optical models and seagrass (Enhalus acoroides, Thalassia hemperichii) distribution in Xincun Bay, Hainan province, and seagrass distribution changes from 1991 to 2006 were analyzed. Hyperspectral results showed that the spectral bands at 555, 635, 650 and 675 nm are sensitive to leaf area index (LAI). Seagrass detection with QuickBird was more accurate than that with Landsat TM and CBERS; five classes could be classified clearly and used as correction for seagrass remote sensing data from Landsat TM and CBERS. In order to better describe seagrass distribution changes, the seagrass distribution area was divided as three regions: region A connected with region B in 1991, however it separated in 1999 and was wholly separated in 2001; seagrass in region C shrank gradually and could not be detected in 2006. Analysis of the reasons for seagrass reduction indicated it was mainly affected by aquaculture and typhoons and in recent years, by land use changes.

  19. Seagrass ecophysiological performance under ocean warming and acidification.

    PubMed

    Repolho, Tiago; Duarte, Bernardo; Dionísio, Gisela; Paula, José Ricardo; Lopes, Ana R; Rosa, Inês C; Grilo, Tiago F; Caçador, Isabel; Calado, Ricardo; Rosa, Rui

    2017-02-01

    Seagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming.

  20. Seagrass ecophysiological performance under ocean warming and acidification

    PubMed Central

    Repolho, Tiago; Duarte, Bernardo; Dionísio, Gisela; Paula, José Ricardo; Lopes, Ana R.; Rosa, Inês C.; Grilo, Tiago F.; Caçador, Isabel; Calado, Ricardo; Rosa, Rui

    2017-01-01

    Seagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming. PMID:28145531

  1. Seagrass ecophysiological performance under ocean warming and acidification

    NASA Astrophysics Data System (ADS)

    Repolho, Tiago; Duarte, Bernardo; Dionísio, Gisela; Paula, José Ricardo; Lopes, Ana R.; Rosa, Inês C.; Grilo, Tiago F.; Caçador, Isabel; Calado, Ricardo; Rosa, Rui

    2017-02-01

    Seagrasses play an essential ecological role within coastal habitats and their worldwide population decline has been linked to different types of anthropogenic forces. We investigated, for the first time, the combined effects of future ocean warming and acidification on fundamental biological processes of Zostera noltii, including shoot density, leaf coloration, photophysiology (electron transport rate, ETR; maximum PSII quantum yield, Fv/Fm) and photosynthetic pigments. Shoot density was severely affected under warming conditions, with a concomitant increase in the frequency of brownish colored leaves (seagrass die-off). Warming was responsible for a significant decrease in ETR and Fv/Fm (particularly under control pH conditions), while promoting the highest ETR variability (among experimental treatments). Warming also elicited a significant increase in pheophytin and carotenoid levels, alongside an increase in carotenoid/chlorophyll ratio and De-Epoxidation State (DES). Acidification significantly affected photosynthetic pigments content (antheraxanthin, β-carotene, violaxanthin and zeaxanthin), with a significant decrease being recorded under the warming scenario. No significant interaction between ocean acidification and warming was observed. Our findings suggest that future ocean warming will be a foremost determinant stressor influencing Z. noltii survival and physiological performance. Additionally, acidification conditions to occur in the future will be unable to counteract deleterious effects posed by ocean warming.

  2. Automatic Abstraction in Planning

    NASA Technical Reports Server (NTRS)

    Christensen, J.

    1991-01-01

    Traditionally, abstraction in planning has been accomplished by either state abstraction or operator abstraction, neither of which has been fully automatic. We present a new method, predicate relaxation, for automatically performing state abstraction. PABLO, a nonlinear hierarchical planner, implements predicate relaxation. Theoretical, as well as empirical results are presented which demonstrate the potential advantages of using predicate relaxation in planning. We also present a new definition of hierarchical operators that allows us to guarantee a limited form of completeness. This new definition is shown to be, in some ways, more flexible than previous definitions of hierarchical operators. Finally, a Classical Truth Criterion is presented that is proven to be sound and complete for a planning formalism that is general enough to include most classical planning formalisms that are based on the STRIPS assumption.

  3. Searching Sociological Abstracts.

    ERIC Educational Resources Information Center

    Kerbel, Sandra Sandor

    1981-01-01

    Describes the scope, content, and retrieval characteristics of Sociological Abstracts, an online database of literature in the social sciences. Sample searches are displayed, and the strengths and weaknesses of the database are summarized. (FM)

  4. Conference Abstracts: AEDS '82.

    ERIC Educational Resources Information Center

    Journal of Computers in Mathematics and Science Teaching, 1982

    1982-01-01

    Abstracts from nine selected papers presented at the 1982 Association for Educational Data Systems (AEDS) conference are provided. Copies of conference proceedings may be obtained for fifteen dollars from the Association. (MP)

  5. Abstracts of SIG Sessions.

    ERIC Educational Resources Information Center

    Proceedings of the ASIS Annual Meeting, 1997

    1997-01-01

    Presents abstracts of SIG Sessions. Highlights include digital collections; information retrieval methods; public interest/fair use; classification and indexing; electronic publication; funding; globalization; information technology projects; interface design; networking in developing countries; metadata; multilingual databases; networked…

  6. Abstracts of contributed papers

    SciTech Connect

    Not Available

    1994-08-01

    This volume contains 571 abstracts of contributed papers to be presented during the Twelfth US National Congress of Applied Mechanics. Abstracts are arranged in the order in which they fall in the program -- the main sessions are listed chronologically in the Table of Contents. The Author Index is in alphabetical order and lists each paper number (matching the schedule in the Final Program) with its corresponding page number in the book.

  7. Distribution and community structure of ichthyoplankton in Laguna Madre seagrass meadows: Potential impact of seagrass species change

    USGS Publications Warehouse

    Tolan, J.M.; Holt, S.A.; Onuf, C.P.

    1997-01-01

    Seasonal ichthyoplankton surveys were made in the lower Laguna Madre, Texas, to compare the relative utilization of various nursery habitats (shoal grass, Halodule wrightii; manatee grass, Syringodium filiforme;, and unvegetated sand bottom) for both estuarine and offshore-spawned larvae. The species composition and abundance of fish larvae were determined for each habitat type at six locations in the bay. Pushnet ichthyoplankton sampling resulted in 296 total collections, yielding 107,463 fishes representing 55 species in 24 families. A broad spectrum of both the biotic and physical habitat parameters were examined to link the dispersion and distribution of both pre-settlement and post-settlement larvae to the utilization of shallow seagrass habitats. Sample sites were grouped by cluster analysis (Ward's minimum variance method) according to the similarity of their fish assemblages and subsequently examined with a multiple discriminant function analysis to identify important environmental variables. Abiotic environmental factors were most influential in defining groups for samples dominated by early larvae, whereas measures of seagrass complexity defined groups dominated by older larvae and juveniles. Juvenile-stage individuals showed clear habitat preference, with the more shallow Halodule wrightii being the habitat of choice, whereas early larvae of most species were widely distributed over all habitats. As a result of the recent shift of dominance from Halodule wrightii to Syringodium filiforme, overall reductions in the quality of nursery habitat for fishes in the lower Laguna Madre are projected.

  8. The functional value of Caribbean coral reef, seagrass and mangrove habitats to ecosystem processes.

    PubMed

    Harborne, Alastair R; Mumby, Peter J; Micheli, Fiorenza; Perry, Christopher T; Dahlgren, Craig P; Holmes, Katherine E; Brumbaugh, Daniel R

    2006-01-01

    Caribbean coral reef habitats, seagrass beds and mangroves provide important goods and services both individually and through functional linkages. A range of anthropogenic factors are threatening the ecological and economic importance of these habitats and it is vital to understand how ecosystem processes vary across seascapes. A greater understanding of processes will facilitate further insight into the effects of disturbances and assist with assessing management options. Despite the need to study processes across whole seascapes, few spatially explicit ecosystem-scale assessments exist. We review the empirical literature to examine the role of different habitat types for a range of processes. The importance of each of 10 generic habitats to each process is defined as its "functional value" (none, low, medium or high), quantitatively derived from published data wherever possible and summarised in a single figure. This summary represents the first time the importance of habitats across an entire Caribbean seascape has been assessed for a range of processes. Furthermore, we review the susceptibility of each habitat to disturbances to investigate spatial patterns that might affect functional values. Habitat types are considered at the scale discriminated by remotely-sensed imagery and we envisage that functional values can be combined with habitat maps to provide spatially explicit information on processes across ecosystems. We provide examples of mapping the functional values of habitats for populations of three commercially important species. The resulting data layers were then used to generate seascape-scale assessments of "hot spots" of functional value that might be considered priorities for conservation. We also provide an example of how the literature reviewed here can be used to parameterise a habitat-specific model investigating reef resilience under different scenarios of herbivory. Finally, we use multidimensional scaling to provide a basic analysis of the

  9. A geospatial modelling approach to predict seagrass habitat recovery under multiple stressor regimes

    EPA Science Inventory

    Restoration of estuarine seagrass habitats requires a clear understanding of the modes of action of multiple interacting stressors including nutrients, climate change, coastal land-use change, and habitat modification. We have developed and demonstrated a geospatial modeling a...

  10. Development of an epiphyte indicator of nutrient enrichment: Threshold values for seagrass epiphyte load

    EPA Science Inventory

    Metrics of epiphyte load on macrophytes were evaluated for use as quantitative biological indicators for nutrient impacts in estuarine waters, based on review and analysis of the literature on epiphytes and macrophytes, primarily seagrasses, but including some brackish and freshw...

  11. Anthropogenic chemicals as drivers of change for coastal ecosystems: wetlands, mangroves and seagrass habitats.

    EPA Science Inventory

    Coastal wetlands, mangrove and seagrass habitats are rapidly declining worldwide which reduces their many ecological services. This presentation summarizes the results of a literature survey conducted to determine scientific understanding of contaminant uptake and toxicity of non...

  12. Applications of C and N stable isotopes to ecological and environmental studies in seagrass ecosystems.

    PubMed

    Lepoint, Gilles; Dauby, Patrick; Gobert, Sylvie

    2004-12-01

    Stable isotopes of carbon and nitrogen are increasingly used in marine ecosystems, for ecological and environmental studies. Here, we examine some applications of stable isotopes as ecological integrators or tracers in seagrass ecosystem studies. We focus on both the use of natural isotope abundance as food web integrators or environmental tracers and on the use of stable isotopes as experimental tools. As ecosystem integrators, stable isotopes have helped to elucidate the general structure of trophic webs in temperate, Mediterranean and tropical seagrass ecosystems. As environmental tracers, stable isotopes have proven their utility in sewage impact measuring and mapping. However, to make such environmental studies more comprehensible, future works on understanding of basic reasons for variations of N and C stable isotopes in seagrasses should be encouraged. At least, as experimental tracers, stable isotopes allow the study of many aspects of N and C cycles at the scale of a plant or at the scale of the seagrass ecosystem.

  13. Evidence for seagrass meadows and their response to paleoenvironmental changes in the early Eocene (Jafnayn Formation, Wadi Bani Khalid, N Oman)

    NASA Astrophysics Data System (ADS)

    Tomás, Sara; Frijia, Gianluca; Bömelburg, Esther; Zamagni, Jessica; Perrin, Christine; Mutti, Maria

    2016-07-01

    The recognition and understanding of vegetated habitats in the fossil record are of crucial importance in order to investigate paleoecological responses and indirectly infer climate and sea-level changes. However, the low preservation potential of plants and macroalgae hampers a direct identification of these environments in the geological past. Here we present sedimentological and paleontological evidences as tool to identify the presence of different seagrass-vegetated environments in the shallow marine settings of the lower Eocene Jafnayn platform of Oman and their responses to paleoenvironmental changes. The studied lower Eocene deposits consist of well bedded, nodular packstones dominated by encrusting acervulinid and alveolinid foraminifera passing upward to an alternance of packstones with echinoids and quartz grains and grainstones rich in Orbitolites, smaller miliolid foraminifera and quartz grains. The presence of seagrass is inferred by the occurrence of encrusting acervulinids and soritid Orbitolites, as well as by their test morphologies together with further sedimentological criteria. The clear shift observed in the faunal assemblages and sedimentary features may be related to a major reorganization of the carbonate system passing from a carbonate platform to a ramp-like platform with increased terrigenous sedimentation. Heterotroph tubular acervulinids and oligotroph alveolinids of the carbonate platform were replaced upward by more heterotroph organisms such as large, discoidal Orbitolites and smaller miliolids, most likely due to enhanced nutrient levels which would have led to a change of phytal substrate, from cylindrical-leaf dominated grasses into flat-leafed ones.

  14. Mapping seagrass coverage and spatial patterns with high spatial resolution IKONOS imagery

    NASA Astrophysics Data System (ADS)

    Pu, Ruiliang; Bell, Susan

    2017-02-01

    Seagrass habitats in subtidal coastal waters provide a variety of ecosystem functions and services and there is an increasing need to acquire information on spatial and temporal dynamics of this resource. Here, we explored the capability of IKONOS (IKO) data of high resolution (4 m) for mapping seagrass cover [submerged aquatic vegetation (%SAV) cover] along the mid-western coast of Florida, USA. We also compared seagrass maps produced with IKO data with that obtained using the Landsat TM sensor with lower resolution (30 m). Both IKO and TM data, collected in October 2009, were preprocessed to calculate water depth invariant bands to normalize the effect of varying depth on bottom spectra recorded by the two satellite sensors and further the textural information was extracted from IKO data. Our results demonstrate that the high resolution IKO sensor produced a higher accuracy than the TM sensor in a three-class % SAV cover classification. Of note is that the OA of %SAV cover mapping at our study area created with IKO data was 5-20% higher than that from other studies published. We also examined the spatial distribution of seagrass over a spatial range of 4-240 m using the Ripley's K function [L(d)] and IKO data that represented four different grain sizes [4 m (one IKO pixel), 8 m (2 × 2 IKO pixels), 12 m (3 × 3 IKO pixels), and 16 m (4 × 4 IKO pixels)] from moderate-dense seagrass cover along a set of six transects. The Ripley's K metric repeatedly indicated that seagrass cover representing 4 m × 4 m pixels displayed a dispersed (or slightly dispersed) pattern over distances of <4-8 m, and a random or slightly clustered pattern of cover over 9-240 m. The spatial pattern of seagrass cover created with the three additional grain sizes (i.e., 2 × 24 m IKO pixels, 3 × 34 m IKO pixels, and 4 × 4 m IKO pixels) show a dispersed (or slightly dispersed) pattern across 4-32 m and a random or slightly clustered pattern across 33-240 m. Given the first report on using

  15. A spatial model to improve site selection for seagrass restoration in shallow boating environments.

    PubMed

    Hotaling-Hagan, Althea; Swett, Robert; Ellis, L Rex; Frazer, Thomas K

    2017-01-15

    Due to widespread and continuing seagrass loss, restoration attempts occur worldwide. This article presents a geospatial modeling technique that ranks the suitability of sites for restoration based on light availability and boating activity, two factors cited in global studies of seagrass loss and restoration failures. The model presented here was created for Estero Bay, Florida and is a predictive model of light availability and boating pressure to aid seagrass restoration efforts. The model is adaptive and can be parameterized for different locations and updated as additional data is collected and knowledge of how factors impact seagrass improves. Light data used for model development were collected over one year from 50 sites throughout the bay. Coupled with high resolution bathymetric data, bottom mean light availability was predicted throughout the bay. Data collection throughout the year also allowed for prediction of light variability at sites, a possible indicator of seagrass growth and survival. Additionally, survey data on boating activities were used to identify areas, outside of marked navigation channels, that receive substantial boating pressure and are likely poor candidate sites for seagrass restoration. The final map product identifies areas where the light environment was suitable for seagrasses and boating pressure was low. A composite map showing the persistence of seagrass coverage in the study area over four years, between 1999 and 2006, was used to validate the model. Eighty-nine percent of the area where seagrass persisted (had been mapped all four years) was ranked as suitable for restoration: 42% with the highest rank (7), 28% with a rank of 6, and 19% with a rank of 5. The results show that the model is a viable tool for selection of seagrass restoration sites in Florida and elsewhere. With knowledge of the light environment and boating patterns, managers will be better equipped to set seagrass restoration and water quality improvement

  16. The degree of urbanization across the globe is not reflected in the δ(15)N of seagrass leaves.

    PubMed

    Christiaen, Bart; Bernard, Rebecca J; Mortazavi, Behzad; Cebrian, Just; Ortmann, Alice C

    2014-06-30

    Many studies show that seagrass δ(15)N ratios increase with the amount of urbanization in coastal watersheds. However, there is little information on the relationship between urbanization and seagrass δ(15)N ratios on a global scale. We performed a meta-analysis on seagrass samples from 79 independent locations to test if seagrass δ(15)N ratios correlate with patterns of population density and fertilizer use within a radius of 10-200 km around the sample locations. Our results show that seagrass δ(15)N ratios are more influenced by intergeneric and latitudinal differences than the degree of urbanization or the amount of fertilizer used in nearby watersheds. The positive correlation between seagrass δ(15)N ratios and latitude hints at an underlying pattern in discrimination or a latitudinal gradient in the (15)N isotopic signature of nitrogen assimilated by the plants. The actual mechanisms responsible for the correlation between δ(15)N and latitude remain unknown.

  17. Developing a methodology of bioindication of human-induced effects using seagrass morphological variation in Spermonde Archipelago, South Sulawesi, Indonesia.

    PubMed

    Ambo-Rappe, Rohani

    2014-09-15

    Seagrass is particularly susceptible to environmental degradation. The objective of the study is to develop an effective bioindicator to assess human-induced effects using morphological variation and fluctuating asymmetry (FA) of seagrass. Samples were collected from eight islands situated at different distance from mainland with different human population density and therefore expected to experience different level of anthropogenic pressure. Cd, Pb, Cu, Zn, nitrate, and phosphate were measured. Metals were also measured in tissues of seagrass. Metal concentrations in sediment, water, and seagrass did not exceed the quality standards required for marine life. Heterogeneity of FA was found among sites suggesting that there are some factors changing developmental instability of seagrass which is not associated to particular toxicants. This baseline study indicates that the water condition is still natural and shows no signs of metal contamination, therefore it does not cause a detectable stress on morphological variation and FA of seagrass.

  18. Metacognition and abstract reasoning.

    PubMed

    Markovits, Henry; Thompson, Valerie A; Brisson, Janie

    2015-05-01

    The nature of people's meta-representations of deductive reasoning is critical to understanding how people control their own reasoning processes. We conducted two studies to examine whether people have a metacognitive representation of abstract validity and whether familiarity alone acts as a separate metacognitive cue. In Study 1, participants were asked to make a series of (1) abstract conditional inferences, (2) concrete conditional inferences with premises having many potential alternative antecedents and thus specifically conducive to the production of responses consistent with conditional logic, or (3) concrete problems with premises having relatively few potential alternative antecedents. Participants gave confidence ratings after each inference. Results show that confidence ratings were positively correlated with logical performance on abstract problems and concrete problems with many potential alternatives, but not with concrete problems with content less conducive to normative responses. Confidence ratings were higher with few alternatives than for abstract content. Study 2 used a generation of contrary-to-fact alternatives task to improve levels of abstract logical performance. The resulting increase in logical performance was mirrored by increases in mean confidence ratings. Results provide evidence for a metacognitive representation based on logical validity, and show that familiarity acts as a separate metacognitive cue.

  19. Limited effects of source population identity and number on seagrass transplant performance.

    PubMed

    Novak, Alyssa B; Plaisted, Holly K; Hays, Cynthia G; Hughes, Randall A

    2017-01-01

    Global declines in coastal foundation species highlight the importance of effective restoration. In this study, we examined the effects of source population identity and diversity (one vs. three sources per plot) on seagrass (Zostera marina) transplant success. The field experiment was replicated at two locations in Massachusetts with adjacent natural Zostera marina beds to test for local adaptation and source diversity effects on shoot density. We also collected morphological and genetic data to characterize variation within and among source populations, and evaluate whether they were related to performance. Transplants grew and expanded until six months post-transplantation, but then steadily declined at both sites. Prior to declines, we observed variation in performance among source populations at one site that was related to morphological traits: the populations with the longest leaves had the highest shoot densities, whereas the population with the shortest leaves performed the worst at six months post-transplantation. In addition, multiple source plots at this same transplant site consistently had similar or higher shoot densities than single source plots, and shoots from weak-performing populations showed improved performance in multiple source plots. We found no evidence for home site advantage or benefits of population-level genetic variation in early transplant performance at either site. Our results show limited effects of source population on early transplant performance and suggest that factors (e.g., morphology) other than home site advantage and population genetic variation serve a role. Based on our overall findings that transplant success varied among source populations and that population diversity at the plot level had positive but limited effects on individual and plot performance, we support planting shoots from multiple source sites in combination to enhance transplant success, particularly in the absence of detailed information on individual

  20. Assessment of genetic diversity of seagrass populations using DNA fingerprinting: implications for population stability and management.

    PubMed Central

    Alberte, R S; Suba, G K; Procaccini, G; Zimmerman, R C; Fain, S R

    1994-01-01

    Populations of the temperate seagrass, Zostera marina L. (eelgrass), often exist as discontinuous beds in estuaries, harbors, and bays where they can reproduce sexually or vegetatively through clonal propagation. We examined the genetic structure of three geographically and morphologically distinct populations from central California (Elkhorn Slough, Tomales Bay, and Del Monte Beach), using multilocus restriction fragment length polymorphisms (DNA fingerprints). Within-population genetic similarity (Sw) values for the three eelgrass populations ranged from 0.44 to 0.68. The Tomales Bay population located in an undisturbed, littoral site possessed a within-population genetic similarity (Sw = 0.44) that was significantly lower than those of the other two populations. Cluster analysis identified genetic substructure in only the undisturbed subtidal population (Del Monte Beach). Between-population similarity values (Sb) for all pairwise comparisons ranged from 0.47 to 0.51. The three eelgrass populations show significantly less between locale genetic similarity than found within populations, indicating that gene flow is restricted between locales even though two of the populations are separated by only 30 km. The study demonstrates that (i) natural populations of Z. marina from both disturbed and undisturbed habitats possess high genetic diversity and are not primarily clonal, (ii) gene flow is restricted even between populations in close proximity, (iii) an intertidal population from a highly disturbed habital shows much lower genetic diversity than an intertidal population from an undisturbed site, and (iv) DNA fingerprinting techniques can be exploited to understand gene flow and population genetic structure in Z. marina, a widespread and ecologically important species, and as such are relevant to the management of this coastal resource. Images PMID:11607458

  1. Limited effects of source population identity and number on seagrass transplant performance

    PubMed Central

    Plaisted, Holly K.; Hays, Cynthia G.; Hughes, Randall A.

    2017-01-01

    Global declines in coastal foundation species highlight the importance of effective restoration. In this study, we examined the effects of source population identity and diversity (one vs. three sources per plot) on seagrass (Zostera marina) transplant success. The field experiment was replicated at two locations in Massachusetts with adjacent natural Zostera marina beds to test for local adaptation and source diversity effects on shoot density. We also collected morphological and genetic data to characterize variation within and among source populations, and evaluate whether they were related to performance. Transplants grew and expanded until six months post-transplantation, but then steadily declined at both sites. Prior to declines, we observed variation in performance among source populations at one site that was related to morphological traits: the populations with the longest leaves had the highest shoot densities, whereas the population with the shortest leaves performed the worst at six months post-transplantation. In addition, multiple source plots at this same transplant site consistently had similar or higher shoot densities than single source plots, and shoots from weak-performing populations showed improved performance in multiple source plots. We found no evidence for home site advantage or benefits of population-level genetic variation in early transplant performance at either site. Our results show limited effects of source population on early transplant performance and suggest that factors (e.g., morphology) other than home site advantage and population genetic variation serve a role. Based on our overall findings that transplant success varied among source populations and that population diversity at the plot level had positive but limited effects on individual and plot performance, we support planting shoots from multiple source sites in combination to enhance transplant success, particularly in the absence of detailed information on individual

  2. Edge Effects along a Seagrass Margin Result in an Increased Grazing Risk on Posidonia australis Transplants

    PubMed Central

    Statton, John; Gustin-Craig, Samuel; Dixon, Kingsley W.; Kendrick, Gary A.

    2015-01-01

    A key issue in habitat restoration are the changes in ecological processes that occur when fragments of habitat are lost, resulting in the persistence of habitat-degraded margins. Margins often create or enhance opportunities for negative plant-herbivore interactions, preventing natural or assisted re-establishment of native vegetation into the degraded area. However, at some distance from the habitat margin these negative interactions may relax. Here, we posit that the intensity of species interactions in a fragmented Posidonia australis seagrass meadow may be spatially dependent on proximity to the seagrass habitat edge, whereby the risk of grazing is high and the probability of survival of seagrass transplants is low. To test this, transplants were planted 2 m within the meadow, on the meadow edge at 0m, and at 2m, 10m, 30m, 50m and 100m distance from the edge of the seagrass meadow into the unvegetated sand sheet. There was an enhanced grazing risk 0-10m from the edge, but decreased sharply with increasing distances (>30m). Yet, the risk of grazing was minimal inside the seagrass meadow, indicating that grazers may use the seagrass meadow for refuge but are not actively grazing within it. The relationship between short-term herbivory risk and long-term survival was not straightforward, suggesting that other environmental filters are also affecting survival of P. australis transplants within the study area. We found that daily probability of herbivory was predictable and operating over a small spatial scale at the edge of a large, intact seagrass meadow. These findings highlight the risk from herbivory can be high, and a potential contributing factor to seagrass establishment in restoration programs. PMID:26465926

  3. Tropical seagrass meadows modify seawater carbon chemistry: implications for coral reefs impacted by ocean acidification

    NASA Astrophysics Data System (ADS)

    Unsworth, Richard K. F.; Collier, Catherine J.; Henderson, Gideon M.; McKenzie, Len J.

    2012-06-01

    Highly productive tropical seagrasses often live adjacent to or among coral reefs and utilize large amounts of inorganic carbon. In this study, the effect of seagrass productivity on seawater carbonate chemistry and coral calcification was modelled on the basis of an analysis of published data. Published data (11 studies, 64 records) reveal that seagrass meadows in the Indo-Pacific have an 83% chance of being net autotrophic, resulting in an average net sink of 155 gC m-2 yr-1. The capacities for seagrass productivity were analysed using an empirical model to examine the effect on seawater carbonate chemistry. Our analyses indicate that increases in pH of up to 0.38 units, and Ωarag increases of 2.9 are possible in the presence of seagrass meadows (compared to their absence) with the precise values of these increases dependent on water residence time (tidal flushing) and water depth. In shallow water reef environments, Scleractinian coral calcification downstream of seagrass has the potential to be ≈18% greater than in an environment without seagrass. If this potential benefit to reef calcifiers is supported by further study it offers a potential tool in marine park management at a local scale. The applicability of this will depend upon local physical conditions as well as the spatial configuration of habitats, and the factors that influence their productivity. This novel study suggests that, in addition to their importance to fisheries, sediment stabilization and primary production, seagrass meadows may enhance coral reef resilience to future ocean acidification.

  4. Transplantation as a method for restoring the seagrass Posidonia australis

    NASA Astrophysics Data System (ADS)

    Bastyan, G. R.; Cambridge, M. L.

    2008-08-01

    Transplant trials of the seagrass Posidonia australis were carried out after loss of seagrasses following eutrophication and increased turbidity in two marine inlets on the south coast of Western Australia. A pilot study in Oyster Harbour measured survival and growth in situ for 4 years. Long-term survival rates were high (96-98%), providing plants were anchored into the sediment. All unanchored plants were lost in the first winter. Following the success of the pilot study, a more comprehensive program began 3 years later with over 500 transplant units collected from either actively growing edges of nearby patches (plagiotropic growth form) or within established meadows (orthotropic growth form). Transplant units from edges expanded at a faster rate compared to units from mid-meadow but increases in shoot numbers were similar. Growth rates in the first 2.5 years averaged 10-20 cm yr -1 horizontal rhizome extension, depending on the source of the transplant units, and 4-12 shoots per initial shoot yr -1, depending on the initial shoot number of the transplant unit. After 5 years, shoot numbers of individual transplants were similar to shoot densities recorded for natural meadows, >500 shoots m -2. Approximately, 10% of transplants from mid-meadow flowered in the first year, whereas transplants from edges flowered only after 5 years. Transplant trials were also established in nearby Princess Royal Harbour at a site selected to test the effect of disturbance by bioturbation from large sand-burrowing worms or by sediment erosion. Survival was lower than in Oyster Harbour, 75-89% in areas with bioturbation but only 14% in areas where sediments were eroded. Growth was poor, <1-2 shoots per shoot yr -1 with high shoot mortality, and low rates of increase in rhizome length, <5 cm yr -1. In areas affected by worm bioturbation, there was almost no horizontal expansion of plants because rhizomes grew vertically to keep pace with sediment deposition. This study showed that

  5. The Power of Three: Coral Reefs, Seagrasses and Mangroves Protect Coastal Regions and Increase Their Resilience

    PubMed Central

    Guannel, Greg; Arkema, Katie; Ruggiero, Peter; Verutes, Gregory

    2016-01-01

    Natural habitats have the ability to protect coastal communities against the impacts of waves and storms, yet it is unclear how different habitats complement each other to reduce those impacts. Here, we investigate the individual and combined coastal protection services supplied by live corals on reefs, seagrass meadows, and mangrove forests during both non-storm and storm conditions, and under present and future sea-level conditions. Using idealized profiles of fringing and barrier reefs, we quantify the services supplied by these habitats using various metrics of inundation and erosion. We find that, together, live corals, seagrasses, and mangroves supply more protection services than any individual habitat or any combination of two habitats. Specifically, we find that, while mangroves are the most effective at protecting the coast under non-storm and storm conditions, live corals and seagrasses also moderate the impact of waves and storms, thereby further reducing the vulnerability of coastal regions. Also, in addition to structural differences, the amount of service supplied by habitats in our analysis is highly dependent on the geomorphic setting, habitat location and forcing conditions: live corals in the fringing reef profile supply more protection services than seagrasses; seagrasses in the barrier reef profile supply more protection services than live corals; and seagrasses, in our simulations, can even compensate for the long-term degradation of the barrier reef. Results of this study demonstrate the importance of taking integrated and place-based approaches when quantifying and managing for the coastal protection services supplied by ecosystems. PMID:27409584

  6. Salt marsh and seagrass communities of Bakkhali Estuary, Cox's Bazar, Bangladesh

    NASA Astrophysics Data System (ADS)

    Hena, M. K. Abu; Short, F. T.; Sharifuzzaman, S. M.; Hasan, M.; Rezowan, M.; Ali, M.

    2007-10-01

    The species identification, distribution pattern, density and biomass of salt marsh and seagrass plants with some of the ecological parameters were studied in the Bakkhali river estuary, Cox's Bazar, Bangladesh during the first half of 2006. Two salt marsh species ( Spartina sp. and Imperata cylindrica) and one seagrass species ( Halophila beccarii) were identified during this investigation, providing the first reports of Spartina sp. and H. beccarii in coastal Bangladesh. Seagrass H. beccarii was found in an accreted area and co-existing with salt marsh, and scattered sparsely in the salt marsh habitat and macroalgae Ulva intestinalis. Flowering and fruiting were recorded from the seagrass H. beccarri during January and February. No flowers and fruits were observed for the salt marsh Spartina sp. during the study period. Results showed that the shoot density of Spartina ranged from 400 to 2875 shoots m -2 with the highest total biomass (165.80 g dry weight (DW) m -2) in March. Shoot density of H. beccarii ranged from 2716 to 14320 shoots m -2 in this estuarine coastal environment. The total biomass of seagrass was higher (17.56 g DW m -2) in March compared to the other months. The highest H. beccarii above ground (AG) biomass and below ground (BG) biomass were 9.59 g DW m -2 and 9.42 g DW m -2, respectively. These parameters are comparable with those generally observed for the salt marsh and seagrass species in the other places of the world.

  7. The Power of Three: Coral Reefs, Seagrasses and Mangroves Protect Coastal Regions and Increase Their Resilience.

    PubMed

    Guannel, Greg; Arkema, Katie; Ruggiero, Peter; Verutes, Gregory

    2016-01-01

    Natural habitats have the ability to protect coastal communities against the impacts of waves and storms, yet it is unclear how different habitats complement each other to reduce those impacts. Here, we investigate the individual and combined coastal protection services supplied by live corals on reefs, seagrass meadows, and mangrove forests during both non-storm and storm conditions, and under present and future sea-level conditions. Using idealized profiles of fringing and barrier reefs, we quantify the services supplied by these habitats using various metrics of inundation and erosion. We find that, together, live corals, seagrasses, and mangroves supply more protection services than any individual habitat or any combination of two habitats. Specifically, we find that, while mangroves are the most effective at protecting the coast under non-storm and storm conditions, live corals and seagrasses also moderate the impact of waves and storms, thereby further reducing the vulnerability of coastal regions. Also, in addition to structural differences, the amount of service supplied by habitats in our analysis is highly dependent on the geomorphic setting, habitat location and forcing conditions: live corals in the fringing reef profile supply more protection services than seagrasses; seagrasses in the barrier reef profile supply more protection services than live corals; and seagrasses, in our simulations, can even compensate for the long-term degradation of the barrier reef. Results of this study demonstrate the importance of taking integrated and place-based approaches when quantifying and managing for the coastal protection services supplied by ecosystems.

  8. Community metabolism in shallow coral reef and seagrass ecosystems, lower Florida Keys

    USGS Publications Warehouse

    Turk, Daniela; Yates, Kimberly K.; Vega-Rodriguez, Maria; Toro-Farmer, Gerardo; L'Esperance, Chris; Melo, Nelson; Ramsewak, Deanesch; Estrada, S. Cerdeira; Muller-Karger, Frank E.; Herwitz, Stan R.; McGillis, Wade

    2016-01-01

    Diurnal variation of net community production (NEP) and net community calcification (NEC) were measured in coral reef and seagrass biomes during October 2012 in the lower Florida Keys using a mesocosm enclosure and the oxygen gradient flux technique. Seagrass and coral reef sites showed diurnal variations of NEP and NEC, with positive values at near-seafloor light levels >100–300 µEinstein m-2 s-1. During daylight hours, we detected an average NEP of 12.3 and 8.6 mmol O2 m-2 h-1 at the seagrass and coral reef site, respectively. At night, NEP at the seagrass site was relatively constant, while on the coral reef, net respiration was highest immediately after dusk and decreased during the rest of the night. At the seagrass site, NEC values ranged from 0.20 g CaCO3 m-2 h-1 during daylight to -0.15 g CaCO3 m-2 h-1 at night, and from 0.17 to -0.10 g CaCO3 m-2 h-1 at the coral reef site. There were no significant differences in pH and aragonite saturation states (Ωar) between the seagrass and coral reef sites. Decrease in light levels during thunderstorms significantly decreased NEP, transforming the system from net autotrophic to net heterotrophic.

  9. Mangroves as a major source of soil carbon storage in adjacent seagrass meadows

    PubMed Central

    Chen, Guangcheng; Azkab, Muhammad Husni; Chmura, Gail L.; Chen, Shunyang; Sastrosuwondo, Pramudji; Ma, Zhiyuan; Dharmawan, I. Wayan Eka; Yin, Xijie; Chen, Bin

    2017-01-01

    Mangrove forests have the potential to export carbon to adjacent ecosystems but whether mangrove-derived organic carbon (OC) would enhance the soil OC storage in seagrass meadows adjacent to mangroves is unclear. In this study we examine the potential for the contribution of mangrove OC to seagrass soils on the coast of North Sulawesi, Indonesia. We found that seagrass meadows adjacent to mangroves had significantly higher soil OC concentrations, soil OC with lower δ 13C, and lower bulk density than those at the non-mangrove adjacent meadows. Soil OC storage to 30 cm depth ranged from 3.21 to 6.82 kg C m−2, and was also significantly higher at the mangrove adjacent meadows than those non-adjacent meadows. δ13C analyses revealed that mangrove OC contributed 34 to 83% to soil OC at the mangrove adjacent meadows. The δ13C value of seagrass plants was also different between the seagrasses adjacent to mangroves and those which were not, with lower values measured at the seagrasses adjacent to mangroves. Moreover, we found significant spatial variation in both soil OC concentration and storage, with values decreasing toward sea, and the contribution of mangrove-derived carbon also reduced with distance from the forest. PMID:28186151

  10. Epiphyte dynamics and carbon metabolism in a nutrient enriched Mediterranean seagrass ( Posidonia oceanica ) ecosystem

    NASA Astrophysics Data System (ADS)

    Apostolaki, Eugenia T.; Holmer, Marianne; Marbà, Núria; Karakassis, Ioannis

    2011-08-01

    The study aimed at examining the relationship between epiphyte dynamics and carbon metabolism in seagrass ecosystems under nutrient enrichment. Temporal variability of epiphytes and factors controlling their dynamics (i.e. environmental conditions, substratum availability, substratum stability and herbivore pressure) were assessed in a fish farm impacted and an unaffected Mediterranean seagrass ( Posidonia oceanica) meadow in the Aegean Sea (Greece). The factors controlling epiphyte dynamics responded differently to nutrient enrichment and partly interacted, rendering their cumulative effect on epiphyte load difficult to elucidate. Yet epiphytes accumulated on seagrass leaves near to the fish farm throughout the year, contributing 2 times more in above-ground biomass at cages than the control station. Reduction in substratum availability (i.e. decrease in leaf biomass) and increase in herbivore pressure affected epiphyte load, albeit their effects were not strong enough to counterbalance the effect of nutrient input from fish farm effluents. Moderate yet continuous nutrient input possibly stimulated epiphyte growth in excess of herbivory, shifting the control of epiphytes from top-down to bottom-up. Epiphyte accumulation affected carbon metabolism in the seagrass ecosystem by contributing to enhanced dissolved organic carbon (DOC) release, but seagrass loss was so acute that increased epiphyte cover could not counterbalance the decrease in community carbon production which was mainly driven by seagrass decline.

  11. Mangroves as a major source of soil carbon storage in adjacent seagrass meadows

    NASA Astrophysics Data System (ADS)

    Chen, Guangcheng; Azkab, Muhammad Husni; Chmura, Gail L.; Chen, Shunyang; Sastrosuwondo, Pramudji; Ma, Zhiyuan; Dharmawan, I. Wayan Eka; Yin, Xijie; Chen, Bin

    2017-02-01

    Mangrove forests have the potential to export carbon to adjacent ecosystems but whether mangrove-derived organic carbon (OC) would enhance the soil OC storage in seagrass meadows adjacent to mangroves is unclear. In this study we examine the potential for the contribution of mangrove OC to seagrass soils on the coast of North Sulawesi, Indonesia. We found that seagrass meadows adjacent to mangroves had significantly higher soil OC concentrations, soil OC with lower δ 13C, and lower bulk density than those at the non-mangrove adjacent meadows. Soil OC storage to 30 cm depth ranged from 3.21 to 6.82 kg C m‑2, and was also significantly higher at the mangrove adjacent meadows than those non-adjacent meadows. δ13C analyses revealed that mangrove OC contributed 34 to 83% to soil OC at the mangrove adjacent meadows. The δ13C value of seagrass plants was also different between the seagrasses adjacent to mangroves and those which were not, with lower values measured at the seagrasses adjacent to mangroves. Moreover, we found significant spatial variation in both soil OC concentration and storage, with values decreasing toward sea, and the contribution of mangrove-derived carbon also reduced with distance from the forest.

  12. Species specific effects of three morphologically different belowground seagrasses on sediment properties

    NASA Astrophysics Data System (ADS)

    Rattanachot, Ekkalak; Prathep, Anchana

    2015-12-01

    Roots and rhizomes of seagrass play an important role in coastline zone by anchoring the substrate firmly which prevent resuspension and also controlling sediment biogeochemistry. The aim of this study was to compare the physical and chemical differences of sediments for 3 seagrass species, which have different root morphology between summer (February 2013) and the monsoon month (September 2013). Seven seagrass communities were studied and are: the mono stand of Halophila ovalis, Thalassia hemprichii, and Cymodocea rotundata, the mixed patches of H. ovalis with T. hemprichii, H. ovalis with C. rotundata, and T. hemprichii with C. rotundata and the mixed patches of 3 seagrass species. The roots of seagrasses were the main driver of differences in sediment properties; the branched, long root species, C. rotundata, showed an increasing redox potential by means of oxygen releasing from their roots. The unbranched, long root with dense root hair species, T. hemprichii, tended to cause more poorly sorted sediments. The carbon storage was also estimated and results showed a trend of higher organic carbon density was in the multispecific patches, the mono specific patches and bare sand, respectively. Season also influenced the sediment properties; high wave action in the monsoon stirred up the sediments, this led to lower organic carbon density and high redox potential. Our results suggest that the roots of seagrass species both increase and decrease sediment properties.

  13. Ecosystem Engineering by Seagrasses Interacts with Grazing to Shape an Intertidal Landscape

    PubMed Central

    van der Heide, Tjisse; Eklöf, Johan S.; van Nes, Egbert H.; van der Zee, Els M.; Donadi, Serena; Weerman, Ellen J.; Olff, Han; Eriksson, Britas Klemens

    2012-01-01

    Self-facilitation through ecosystem engineering (i.e., organism modification of the abiotic environment) and consumer-resource interactions are both major determinants of spatial patchiness in ecosystems. However, interactive effects of these two mechanisms on spatial complexity have not been extensively studied. We investigated the mechanisms underlying a spatial mosaic of low-tide exposed hummocks and waterlogged hollows on an intertidal mudflat in the Wadden Sea dominated by the seagrass Zostera noltii. A combination of field measurements, an experiment and a spatially explicit model indicated that the mosaic resulted from localized sediment accretion by seagrass followed by selective waterfowl grazing. Hollows were bare in winter, but were rapidly colonized by seagrass during the growth season. Colonized hollows were heavily grazed by brent geese and widgeon in autumn, converting these patches to a bare state again and disrupting sediment accretion by seagrass. In contrast, hummocks were covered by seagrass throughout the year and were rarely grazed, most likely because the waterfowl were not able to employ their preferred but water requiring feeding strategy (‘dabbling’) here. Our study exemplifies that interactions between ecosystem engineering by a foundation species (seagrass) and consumption (waterfowl grazing) can increase spatial complexity at the landscape level. PMID:22905115

  14. Influence of New Zealand cockles (Austrovenus stutchburyi) on primary productivity in sandflat-seagrass (Zostera muelleri) ecotones

    NASA Astrophysics Data System (ADS)

    Lohrer, Andrew M.; Townsend, Michael; Hailes, Sarah F.; Rodil, Iván F.; Cartner, Katie; Pratt, Daniel R.; Hewitt, Judi E.

    2016-11-01

    New Zealand cockles (Austrovenus stutchburyi) are ecologically important, intertidal bivalves that have been shown to influence nutrient cycles and the productivity of microphytobenthos on sandflats. Here, we investigated the potential for cockles to impact the productivity of seagrass, Zostera muelleri, and examined interactions between these habitat-defining species where they co-occur. We sampled bivalve densities and sizes, sediment properties, and seagrass shoot densities across the boundaries of two seagrass patches on an intertidal sandflat in northern New Zealand, and measured dissolved oxygen and nutrient fluxes in light and dark benthic incubation chambers in conjunction with a 0-97% gradient in seagrass cover. Although gross primary production (GPP, μmol O2 m-2 h-1) increased predictably with the cover of live seagrass, the density of cockles and sediment properties also contributed directly and indirectly. Seagrass cover was positively correlated with cockle density (ranging from 225 to 1350 individuals per m2), sediment mud percentage (0.5-9.5%), and organic matter content (0.5-2.2%), all of which can affect the efflux of ammonium (readily utilisable inorganic nitrogen) from sediments. Moreover, the cover of green seagrass blades plateaued (never exceeded 70%) in the areas of highest total seagrass cover, adding complexity to cockle-seagrass interactions and contributing to a unimodal cockle-GPP relationship.

  15. Declines of seagrasses in a tropical harbour, North Queensland, Australia, are not the result of a single event.

    PubMed

    McKENNA, Skye; Jarvis, Jessie; Sankey, Tonia; Reason, Carissa; Coles, Robert; Rasheed, Michael

    2015-06-01

    A recent paper inferred that all seagrass in Cairns Harbour, tropical north-eastern Australia, had undergone 'complete and catastrophic loss' as a result of tropical cyclone Yasi in 2011. While we agree with the concern expressed, we would like to correct the suggestion that the declines were the result of a single climatic event and that all seagrass in Cairns Harbour were lost. Recent survey data and trend analysis from an on-ground monitoring program show that seagrasses in Cairns Harbour do remain, albeit at low levels, and the decline in seagrasses occurred over several years with cyclone Yasi having little additional impact. We have conducted annual on-ground surveys of seagrass distribution and the above-ground meadow biomass in Cairns Harbour and Trinity Inlet since 2001. This has shown a declining trend in biomass since a peak in 2004 and in area since it peaked in 2007. In 2012, seagrass area and above-ground biomass were significantly below the long-term (12 year) average but seagrass was still present. Declines were associated with regional impacts on coastal seagrasses from multiple years of above-average rainfall and severe storm and cyclone activity, similar to other nearby seagrass areas, and not as a result of a single event.

  16. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 7 Agriculture 15 2011-01-01 2011-01-01 false Bedding, bed linens, and towels. 2902.15 Section 2902... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  17. 7 CFR 3201.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 7 Agriculture 15 2013-01-01 2013-01-01 false Bedding, bed linens, and towels. 3201.15 Section 3201... PROCUREMENT Designated Items § 3201.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  18. 7 CFR 3201.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 7 Agriculture 15 2012-01-01 2012-01-01 false Bedding, bed linens, and towels. 3201.15 Section 3201... PROCUREMENT Designated Items § 3201.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  19. 7 CFR 2902.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 7 Agriculture 15 2010-01-01 2010-01-01 false Bedding, bed linens, and towels. 2902.15 Section 2902... PROCUREMENT Designated Items § 2902.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  20. 7 CFR 3201.15 - Bedding, bed linens, and towels.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 7 Agriculture 15 2014-01-01 2014-01-01 false Bedding, bed linens, and towels. 3201.15 Section 3201... PROCUREMENT Designated Items § 3201.15 Bedding, bed linens, and towels. (a) Definition. (1) Bedding is that..., bedspreads, comforters, and quilts. (2) Bed linens are woven cloth sheets and pillowcases used in bedding....

  1. Response of a seagrass fish assemblage to improved wastewater treatment.

    PubMed

    Ourgaud, M; Ruitton, S; Bell, J D; Letourneur, Y; Harmelin, J G; Harmelin-Vivien, M L

    2015-01-15

    We compared the structure of a seagrass fish assemblage near a sewage outlet before and after improvements to wastewater treatment. To determine whether responses by the fish assemblage were due to changes in water quality or to other factors, comparisons were made with the structure of a fish assemblage from a nearby site unaffected by sewage effluent. Total species richness, density and biomass of fish, decreased at both sites over the 30-year period. An increase in mean trophic level near the sewage outlet following improvements in water quality indicated that wastewater treatment had another important effect. This result is consistent with the reductions in food webs supporting pelagic and benthic fishes that typically accompany decreases in nutrient inputs. Although improvements to wastewater treatment explained much of the variation in the structure of the fish assemblage at PC, our results also suggest that fishing and climate change, at both sites.

  2. Using vertical Sidescan Sonar as a tool for seagrass cartography

    NASA Astrophysics Data System (ADS)

    Sánchez-Carnero, N.; Rodríguez-Pérez, D.; Couñago, E.; Aceña, S.; Freire, J.

    2012-12-01

    An acoustic method, a vertically oriented Sidescan Sonar (SSSv), is used to detect and map Posidonia oceanica meadows in the bay of Agua Amarga (SE of the Mediterranean coast of Spain). Sidescan sonar, among other active hydroacoustic techniques, has shown its ability to detect, map and monitor seagrass based on its acoustic backscatter; however, some limitations linked to its power based approach have been reported in the literature. Our method is based on the SSSv measurement of canopy height distribution, making the most use of the SSSv acoustic data and using existing algorithms as statistical mapping methods. The results show a spatially coherent and statistically consistent classification. The comparison with groundtruthing is difficult due to the steep variations in the seafloor cover found in the area of interest, nevertheless the validation is successful (proving low-order discrimination) in a zone with a large range of depth variations (0-25 m).

  3. Seagrass tolerance to herbivory under increased ocean temperatures.

    PubMed

    Garthwin, Ruby G; Poore, Alistair G B; Vergés, Adriana

    2014-06-30

    Climate change is acknowledged as a major threat to marine ecosystems, but the effect of temperature on species interactions remains poorly understood. We quantified the effects of long-term warming on plant-herbivore interactions of a dominant seagrass, Zostera muelleri. Growth, herbivory and tolerance to damage were compared between a meadow warmed by the thermal plume from a power station for 30 years (2-3 °C above background temperatures) and three control locations. Leaf growth rates and tissue loss were spatially variable but unrelated to temperature regimes. Natural herbivory was generally low. Simulated herbivory experiments showed that the tolerance of Z. muelleri to defoliation did not differ between warm and unimpacted meadows, with damaged and undamaged plants maintaining similar growth rates irrespective of temperature. These results suggest that the ability of temperate Z. muelleri to tolerate herbivory is not strongly influenced by warming, and this species may be relatively resilient to future environmental change.

  4. Leadership Abstracts, 2001.

    ERIC Educational Resources Information Center

    Wilson, Cynthia, Ed.

    2001-01-01

    This is volume 14 of Leadership Abstracts, a newsletter published by the League for Innovation (California). Issue 1 of February 2001, "Developmental Education: A Policy Primer," discusses developmental programs in the community college. According to the article, community college trustees and presidents would serve their constituents well by…

  5. Abstract Film and Beyond.

    ERIC Educational Resources Information Center

    Le Grice, Malcolm

    A theoretical and historical account of the main preoccupations of makers of abstract films is presented in this book. The book's scope includes discussion of nonrepresentational forms as well as examination of experiments in the manipulation of time in films. The ten chapters discuss the following topics: art and cinematography, the first…

  6. Leadership Abstracts, 1993.

    ERIC Educational Resources Information Center

    Doucette, Don, Ed.

    1993-01-01

    This document includes 10 issues of Leadership Abstracts (volume 6, 1993), a newsletter published by the League for Innovation in the Community College (California). The featured articles are: (1) "Reinventing Government" by David T. Osborne; (2) "Community College Workforce Training Programs: Expanding the Mission to Meet Critical Needs" by…

  7. Leadership Abstracts, 1999.

    ERIC Educational Resources Information Center

    Leadership Abstracts, 1999

    1999-01-01

    This document contains five Leadership Abstracts publications published February-December 1999. The article, "Teaching the Teachers: Meeting the National Teacher Preparation Challenge," authored by George R. Boggs and Sadie Bragg, examines the community college role and makes recommendations and a call to action for teacher education.…

  8. Computers in Abstract Algebra

    ERIC Educational Resources Information Center

    Nwabueze, Kenneth K.

    2004-01-01

    The current emphasis on flexible modes of mathematics delivery involving new information and communication technology (ICT) at the university level is perhaps a reaction to the recent change in the objectives of education. Abstract algebra seems to be one area of mathematics virtually crying out for computer instructional support because of the…

  9. 2002 NASPSA Conference Abstracts.

    ERIC Educational Resources Information Center

    Journal of Sport & Exercise Psychology, 2002

    2002-01-01

    Contains abstracts from the 2002 conference of the North American Society for the Psychology of Sport and Physical Activity. The publication is divided into three sections: the preconference workshop, "Effective Teaching Methods in the Classroom;" symposia (motor development, motor learning and control, and sport psychology); and free…

  10. Reasoning abstractly about resources

    NASA Technical Reports Server (NTRS)

    Clement, B.; Barrett, A.

    2001-01-01

    r describes a way to schedule high level activities before distributing them across multiple rovers in order to coordinate the resultant use of shared resources regardless of how each rover decides how to perform its activities. We present an algorithm for summarizing the metric resource requirements of an abstract activity based n the resource usages of its potential refinements.

  11. Conference Abstracts: AEDS '84.

    ERIC Educational Resources Information Center

    Baird, William E.

    1985-01-01

    The Association of Educational Data Systems (AEDS) conference included 102 presentations. Abstracts of seven of these presentations are provided. Topic areas considered include LOGO, teaching probability through a computer game, writing effective computer assisted instructional materials, computer literacy, research on instructional…

  12. Leadership Abstracts, 2002.

    ERIC Educational Resources Information Center

    Wilson, Cynthia, Ed.; Milliron, Mark David, Ed.

    2002-01-01

    This 2002 volume of Leadership Abstracts contains issue numbers 1-12. Articles include: (1) "Skills Certification and Workforce Development: Partnering with Industry and Ourselves," by Jeffrey A. Cantor; (2) "Starting Again: The Brookhaven Success College," by Alice W. Villadsen; (3) "From Digital Divide to Digital Democracy," by Gerardo E. de los…

  13. Abstraction and art.

    PubMed Central

    Gortais, Bernard

    2003-01-01

    In a given social context, artistic creation comprises a set of processes, which relate to the activity of the artist and the activity of the spectator. Through these processes we see and understand that the world is vaster than it is said to be. Artistic processes are mediated experiences that open up the world. A successful work of art expresses a reality beyond actual reality: it suggests an unknown world using the means and the signs of the known world. Artistic practices incorporate the means of creation developed by science and technology and change forms as they change. Artists and the public follow different processes of abstraction at different levels, in the definition of the means of creation, of representation and of perception of a work of art. This paper examines how the processes of abstraction are used within the framework of the visual arts and abstract painting, which appeared during a period of growing importance for the processes of abstraction in science and technology, at the beginning of the twentieth century. The development of digital platforms and new man-machine interfaces allow multimedia creations. This is performed under the constraint of phases of multidisciplinary conceptualization using generic representation languages, which tend to abolish traditional frontiers between the arts: visual arts, drama, dance and music. PMID:12903659

  14. Annual Conference Abstracts

    ERIC Educational Resources Information Center

    Journal of Engineering Education, 1972

    1972-01-01

    Includes abstracts of papers presented at the 80th Annual Conference of the American Society for Engineering Education. The broad areas include aerospace, affiliate and associate member council, agricultural engineering, biomedical engineering, continuing engineering studies, chemical engineering, civil engineering, computers, cooperative…

  15. Abstracts of SIG Sessions.

    ERIC Educational Resources Information Center

    Proceedings of the ASIS Annual Meeting, 1994

    1994-01-01

    Includes abstracts of 18 special interest group (SIG) sessions. Highlights include natural language processing, information science and terminology science, classification, knowledge-intensive information systems, information value and ownership issues, economics and theories of information science, information retrieval interfaces, fuzzy thinking…

  16. RESEARCH ABSTRACTS, VOLUME VI.

    ERIC Educational Resources Information Center

    COLETTE, SISTER M.

    THIS SIXTH VOLUME OF RESEARCH ABSTRACTS PRESENTS REPORTS OF 35 RESEARCH STUDIES COMPLETED BY CANDIDATES FOR THE MASTER'S DEGREE AT THE CARDINAL STRITCH COLLEGE IN 1964. TWENTY-NINE STUDIES ARE CONCERNED WITH READING, AND SIX ARE CONCERNED WITH THE EDUCATION OF THE MENTALLY HANDICAPPED. OF THE READING STUDIES, FIVE PERTAIN TO THE JUNIOR HIGH LEVEL…

  17. Learning Abstracts, 1999.

    ERIC Educational Resources Information Center

    League for Innovation in the Community Coll.

    This document contains volume two of Learning Abstracts, a bimonthly newsletter from the League for Innovation in the Community College. Articles in these seven issues include: (1) "Get on the Fast Track to Learning: An Accelerated Associate Degree Option" (Gerardo E. de los Santos and Deborah J. Cruise); (2) "The Learning College:…

  18. Annual Conference Abstracts

    ERIC Educational Resources Information Center

    Engineering Education, 1976

    1976-01-01

    Presents the abstracts of 158 papers presented at the American Society for Engineering Education's annual conference at Knoxville, Tennessee, June 14-17, 1976. Included are engineering topics covering education, aerospace, agriculture, biomedicine, chemistry, computers, electricity, acoustics, environment, mechanics, and women. (SL)

  19. Making the Abstract Concrete

    ERIC Educational Resources Information Center

    Potter, Lee Ann

    2005-01-01

    President Ronald Reagan nominated a woman to serve on the United States Supreme Court. He did so through a single-page form letter, completed in part by hand and in part by typewriter, announcing Sandra Day O'Connor as his nominee. While the document serves as evidence of a historic event, it is also a tangible illustration of abstract concepts…

  20. Abstracts of SIG Sessions.

    ERIC Educational Resources Information Center

    Proceedings of the ASIS Annual Meeting, 1995

    1995-01-01

    Presents abstracts of 15 special interest group (SIG) sessions. Topics include navigation and information utilization in the Internet, natural language processing, automatic indexing, image indexing, classification, users' models of database searching, online public access catalogs, education for information professions, information services,…

  1. Seismic Consequence Abstraction

    SciTech Connect

    M. Gross

    2004-10-25

    The primary purpose of this model report is to develop abstractions for the response of engineered barrier system (EBS) components to seismic hazards at a geologic repository at Yucca Mountain, Nevada, and to define the methodology for using these abstractions in a seismic scenario class for the Total System Performance Assessment - License Application (TSPA-LA). A secondary purpose of this model report is to provide information for criticality studies related to seismic hazards. The seismic hazards addressed herein are vibratory ground motion, fault displacement, and rockfall due to ground motion. The EBS components are the drip shield, the waste package, and the fuel cladding. The requirements for development of the abstractions and the associated algorithms for the seismic scenario class are defined in ''Technical Work Plan For: Regulatory Integration Modeling of Drift Degradation, Waste Package and Drip Shield Vibratory Motion and Seismic Consequences'' (BSC 2004 [DIRS 171520]). The development of these abstractions will provide a more complete representation of flow into and transport from the EBS under disruptive events. The results from this development will also address portions of integrated subissue ENG2, Mechanical Disruption of Engineered Barriers, including the acceptance criteria for this subissue defined in Section 2.2.1.3.2.3 of the ''Yucca Mountain Review Plan, Final Report'' (NRC 2003 [DIRS 163274]).

  2. Abstraction through Game Play

    ERIC Educational Resources Information Center

    Avraamidou, Antri; Monaghan, John; Walker, Aisha

    2012-01-01

    This paper examines the computer game play of an 11-year-old boy. In the course of building a virtual house he developed and used, without assistance, an artefact and an accompanying strategy to ensure that his house was symmetric. We argue that the creation and use of this artefact-strategy is a mathematical abstraction. The discussion…

  3. EBS Radionuclide Transport Abstraction

    SciTech Connect

    R. Schreiner

    2001-06-27

    The purpose of this work is to develop the Engineered Barrier System (EBS) radionuclide transport abstraction model, as directed by a written development plan (CRWMS M&O 1999a). This abstraction is the conceptual model that will be used to determine the rate of release of radionuclides from the EBS to the unsaturated zone (UZ) in the total system performance assessment-license application (TSPA-LA). In particular, this model will be used to quantify the time-dependent radionuclide releases from a failed waste package (WP) and their subsequent transport through the EBS to the emplacement drift wall/UZ interface. The development of this conceptual model will allow Performance Assessment Operations (PAO) and its Engineered Barrier Performance Department to provide a more detailed and complete EBS flow and transport abstraction. The results from this conceptual model will allow PA0 to address portions of the key technical issues (KTIs) presented in three NRC Issue Resolution Status Reports (IRSRs): (1) the Evolution of the Near-Field Environment (ENFE), Revision 2 (NRC 1999a), (2) the Container Life and Source Term (CLST), Revision 2 (NRC 1999b), and (3) the Thermal Effects on Flow (TEF), Revision 1 (NRC 1998). The conceptual model for flow and transport in the EBS will be referred to as the ''EBS RT Abstraction'' in this analysis/modeling report (AMR). The scope of this abstraction and report is limited to flow and transport processes. More specifically, this AMR does not discuss elements of the TSPA-SR and TSPA-LA that relate to the EBS but are discussed in other AMRs. These elements include corrosion processes, radionuclide solubility limits, waste form dissolution rates and concentrations of colloidal particles that are generally represented as boundary conditions or input parameters for the EBS RT Abstraction. In effect, this AMR provides the algorithms for transporting radionuclides using the flow geometry and radionuclide concentrations determined by other

  4. Seed germination in a southern Australian temperate seagrass.

    PubMed

    Cumming, Erin; Jarvis, Jessie C; Sherman, Craig D H; York, Paul H; Smith, Timothy M

    2017-01-01

    In a series of experiments, seeds from a temperate seagrass species, Zostera nigricaulis collected in Port Phillip Bay, Victoria, Australia were exposed to a range of salinities (20 PSU pulse/no pulse, 25 PSU, 30 PSU, 35 PSU), temperatures (13 °C, 17 °C, 22 °C), burial depths (0 cm, 1 cm, 2 cm) and site specific sediment characteristics (fine, medium, coarse) to quantify their impacts on germination rate and maximum overall germination. In southern Australia the seagrass Z. nigricaulis is a common subtidal species; however, little is known about the factors that affect seed germination which is a potential limiting factor in meadow resilience to natural and anthropogenic disturbances. Overall seed germination was low (<20%) with germination decreasing to <10% when seeds were placed in the sediment. When germination of Z. nigricaulis seeds was observed, it was enhanced (greater overall germination and shorter time to germination) when seeds were exposed to a 20 PSU pulse for 24 h, maintained at salinity of 25 PSU, temperatures <13 °C, in sediments with fine or medium grain sand and buried at a depth of <1 cm. These results indicate that germination of Z. nigricaulis seeds under in situ conditions may be seasonally limited by temperatures in southern Australia. Seed germination may be further restricted by salinity as freshwater pulses reaching 20 PSU are typically only observed in Port Phillip Bay following large scale rainfall events. As a result, these populations may be particularly susceptible to disturbance with only a seasonally limited capacity for recovery.

  5. Seed germination in a southern Australian temperate seagrass

    PubMed Central

    Jarvis, Jessie C.; Sherman, Craig D.H.; York, Paul H.; Smith, Timothy M.

    2017-01-01

    In a series of experiments, seeds from a temperate seagrass species, Zostera nigricaulis collected in Port Phillip Bay, Victoria, Australia were exposed to a range of salinities (20 PSU pulse/no pulse, 25 PSU, 30 PSU, 35 PSU), temperatures (13 °C, 17 °C, 22 °C), burial depths (0 cm, 1 cm, 2 cm) and site specific sediment characteristics (fine, medium, coarse) to quantify their impacts on germination rate and maximum overall germination. In southern Australia the seagrass Z. nigricaulis is a common subtidal species; however, little is known about the factors that affect seed germination which is a potential limiting factor in meadow resilience to natural and anthropogenic disturbances. Overall seed germination was low (<20%) with germination decreasing to <10% when seeds were placed in the sediment. When germination of Z. nigricaulis seeds was observed, it was enhanced (greater overall germination and shorter time to germination) when seeds were exposed to a 20 PSU pulse for 24 h, maintained at salinity of 25 PSU, temperatures <13 °C, in sediments with fine or medium grain sand and buried at a depth of <1 cm. These results indicate that germination of Z. nigricaulis seeds under in situ conditions may be seasonally limited by temperatures in southern Australia. Seed germination may be further restricted by salinity as freshwater pulses reaching 20 PSU are typically only observed in Port Phillip Bay following large scale rainfall events. As a result, these populations may be particularly susceptible to disturbance with only a seasonally limited capacity for recovery. PMID:28348932

  6. Review of nekton patterns and ecological processes in seagrass landscapes

    NASA Astrophysics Data System (ADS)

    Connolly, Rod M.; Hindell, Jeremy S.

    2006-07-01

    We reviewed seagrass landscape studies on nekton (fish and larger mobile crustaceans) to summarise: (1) patterns of nekton abundance in relation to patch attributes; and (2) models used to explain processes underpinning observed patterns. The response of nekton to landscape attributes is highly variable. Different taxa showed increasing densities with: increasing and decreasing patch size (12 and 11 taxa, respectively), increasing and decreasing proximity within a patch to edge (9, 14), increasing and decreasing distances from nearest seagrass patch (4, 11), and with patches perpendicular and parallel to currents (1, 2). The majority of taxa (213 out of 281, or 82%) showed no relationships. Landscape scale patterns are important for some species but evidence so far does not demonstrate major landscape effects overall. The lack of pattern might reflect the overriding importance of other factors such as within-patch characteristics, water depth or position within an estuary. It might also result from measurements at the wrong scale. The rigour of surveys can be improved by avoiding confounding of patch attributes by other factors, increasing awareness of statistical power, and more considered survey designs for attributes such as edge effects. The predation model is the most frequently invoked and tested model. Other explanatory models are based on disturbance, rates of encounter, food availability, larval supply, migration and reproductive success, but in many cases are not based on observed patterns. The best experimental work has been done on nekton species for which landscape studies have been built on a detailed understanding of the ecology of the species, such as for blue crabs ( Callinectes sapidus). As this basic ecological platform is laid for more species, the landscape approach will become increasingly fruitful.

  7. Hybrid fluidized bed combuster

    DOEpatents

    Kantesaria, Prabhudas P.; Matthews, Francis T.

    1982-01-01

    A first atmospheric bubbling fluidized bed furnace is combined with a second turbulent, circulating fluidized bed furnace to produce heat efficiently from crushed solid fuel. The bed of the second furnace receives the smaller sizes of crushed solid fuel, unreacted limestone from the first bed, and elutriated solids extracted from the flu gases of the first bed. The two-stage combustion of crushed solid fuel provides a system with an efficiency greater than available with use of a single furnace of a fluidized bed.

  8. A GIS Analysis of Seagrass Resources and Condition Within Padre Island National Seashore, Texas

    USGS Publications Warehouse

    Onuf, Christopher P.; Ingold, Jaimie J.

    2007-01-01

    A survey of the seagrass resources of Padre Island National Seashore was conducted in fall 2002 and 2003, with additional sampling through 2006, to resolve distribution questions. Location coordinates were recorded to thousandths of minutes of latitude and longitude and converted to decimal degrees (minus decimal degrees for longitude) for import into ArcView (Environmental Systems Research Institute, Inc.). The seagrass core frequency data were developed as a theme in ArcView and overlaid on digital orthophoto quarter quadrangles of the U.S. Geological Survey to show sample depth with respect to mean sea level and frequency of occurrence of seagrass for five samples collected from every station sampled. These data were used to draw boundaries of area submerged at mean sea level and seagrass meadow in relation to the boundary of Padre Island National Seashore. Frequency of seagrass occurrence, mean plant height, shoot density, plant height multiplied by shoot density, live biomass, and dead biomass on a 1' latitude by 0.25' longitude grid were collected, and their distribution was plotted in space and according to depth. A User Guide for displaying data in ArcView is included at the end of this report. Seagrasses covered almost two-thirds of the regularly flooded part of Laguna Madre within the borders of Padre Island National Seashore. Comparisons with earlier surveys showed that substantial areas of seagrass cover had been lost in deep water between 1988 and 1998 as a result of a persistent phytoplankton bloom, and little recovery has occurred since. Maximum depth of seagrass occurrence responded to changes in water clarity. In contrast, much of the cover at shallow to intermediate depths lost at the south end of the study area between 1988 and 1998 was replaced by 2003. The seven stations with greatest plant height were located in this area of recent recolonization. Continuity of cover as measured by frequency of occurrence was high except near the edge of

  9. Bed material agglomeration during fluidized bed combustion

    SciTech Connect

    Brown, R.C.; Dawson, M.R.; Noble, S.

    1993-02-01

    The purpose of this project is to determine the physical and chemical reactions which led to the undesired agglomeration of bed material during fluidized bed combustion and to relate these reactions to specific causes. Survey of industrial-scale fluidized bed combustors is being conducted to determine the occurrence of bed agglomeration and the circumstances under which agglomeration took place. This task should be finished by the end of February. Samples of bed material, agglomerate material, and boiler deposits are being requested from boiler operators as part of the survey. Once received, these sample will be analyzed to determine chemical and mineralogic composition. The bulk chemical determination will be performed using x-ray fluorescence and inductively coupled plasma-optical emission (ICP). Mineralogy will be detected by x-ray diffraction (XRD). Chemical and mineral reactions will be determined by scanning electron microscopy, optical microscopy, and electron microprobe.

  10. Generalized Abstract Symbolic Summaries

    NASA Technical Reports Server (NTRS)

    Person, Suzette; Dwyer, Matthew B.

    2009-01-01

    Current techniques for validating and verifying program changes often consider the entire program, even for small changes, leading to enormous V&V costs over a program s lifetime. This is due, in large part, to the use of syntactic program techniques which are necessarily imprecise. Building on recent advances in symbolic execution of heap manipulating programs, in this paper, we develop techniques for performing abstract semantic differencing of program behaviors that offer the potential for improved precision.

  11. Abstraction Augmented Markov Models.

    PubMed

    Caragea, Cornelia; Silvescu, Adrian; Caragea, Doina; Honavar, Vasant

    2010-12-13

    High accuracy sequence classification often requires the use of higher order Markov models (MMs). However, the number of MM parameters increases exponentially with the range of direct dependencies between sequence elements, thereby increasing the risk of overfitting when the data set is limited in size. We present abstraction augmented Markov models (AAMMs) that effectively reduce the number of numeric parameters of k(th) order MMs by successively grouping strings of length k (i.e., k-grams) into abstraction hierarchies. We evaluate AAMMs on three protein subcellular localization prediction tasks. The results of our experiments show that abstraction makes it possible to construct predictive models that use significantly smaller number of features (by one to three orders of magnitude) as compared to MMs. AAMMs are competitive with and, in some cases, significantly outperform MMs. Moreover, the results show that AAMMs often perform significantly better than variable order Markov models, such as decomposed context tree weighting, prediction by partial match, and probabilistic suffix trees.

  12. Bed Bugs and Schools

    EPA Pesticide Factsheets

    Bed bugs have long been a pest – feeding on blood, causing itchy bites and generally irritating their human hosts. They are successful hitchhikers, and can move from an infested site to furniture, bedding, baggage, boxes, and clothing.

  13. Bed rest during pregnancy

    MedlinePlus

    ... on the inferior vena cava. How Can I Deal with Discomfort from Bed Rest? Bed rest can ... Group Health Cooperative, Bellevue, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the ...

  14. Application of Landsat images to seagrass areal cover change analysis for Lawas, Terengganu and Kelantan of Malaysia

    NASA Astrophysics Data System (ADS)

    Hossain, M. S.; Bujang, J. S.; Zakaria, M. H.; Hashim, M.

    2015-11-01

    Seagrass mapping and monitoring using remote sensing has been established using various imageries and mapping methods, ranging from complex optical modeling to manual interpretations. Few attempts have been made to find relations between spatiotemporal changes within seagrass habitats and their surrounding environment in the mapping efforts. In this study, issues of spatiotemporal changes in seagrass habitat including water quality, and causes and processes of seagrass degradation were addressed through assessing the ability of integrated manual enhancement and seed pixel growing techniques on multi-date Landsat images for mapping and monitoring seagrass resources. This integrated approach was tested on a total of forty-nine Landsat 5, 7 and 8 images of the seagrass meadow spatial distribution and cover change analysis for Punag-Sari estuary (Lawas), Pengkalan Nangka (Kelantan) lagoon, and Paka (Terengganu) lagoon of Malaysia. The resulted maps demonstrated the ability of Landsat images for producing spatially extensive maps and allowed quantitative estimation of seagrass coverage, accretion/erosion, and describe changes in noticeable areas. The findings indicated that a noticeable loss of seagrass habitats at varying magnitude occurred between 2000 and 2014 for Punang-Sari, between 1998 and 2014 for Pegkalan Nangka, and between 1988 and 2014 for Paka. The natural event mainly sand shifting was the main cause of seagrass habitat loss for Punang-Sari Lawas. Coastline change was identified as the most significant factor that caused seagrass spatial cover loss of the Pengkalan Nangka lagoon. The seagrass meadows of Pengkalan Nangka and Paka were greatly affected by natural events including floods, and local human-induced interferences such as dredging, and sand mining. The mapping approach and the map products presented in this paper will be a useful information source for the coastal management agencies involved in monitoring and management programs.

  15. EBS Radionuclide Transport Abstraction

    SciTech Connect

    J. Prouty

    2006-07-14

    The purpose of this report is to develop and analyze the engineered barrier system (EBS) radionuclide transport abstraction model, consistent with Level I and Level II model validation, as identified in Technical Work Plan for: Near-Field Environment and Transport: Engineered Barrier System: Radionuclide Transport Abstraction Model Report Integration (BSC 2005 [DIRS 173617]). The EBS radionuclide transport abstraction (or EBS RT Abstraction) is the conceptual model used in the total system performance assessment (TSPA) to determine the rate of radionuclide releases from the EBS to the unsaturated zone (UZ). The EBS RT Abstraction conceptual model consists of two main components: a flow model and a transport model. Both models are developed mathematically from first principles in order to show explicitly what assumptions, simplifications, and approximations are incorporated into the models used in the TSPA. The flow model defines the pathways for water flow in the EBS and specifies how the flow rate is computed in each pathway. Input to this model includes the seepage flux into a drift. The seepage flux is potentially split by the drip shield, with some (or all) of the flux being diverted by the drip shield and some passing through breaches in the drip shield that might result from corrosion or seismic damage. The flux through drip shield breaches is potentially split by the waste package, with some (or all) of the flux being diverted by the waste package and some passing through waste package breaches that might result from corrosion or seismic damage. Neither the drip shield nor the waste package survives an igneous intrusion, so the flux splitting submodel is not used in the igneous scenario class. The flow model is validated in an independent model validation technical review. The drip shield and waste package flux splitting algorithms are developed and validated using experimental data. The transport model considers advective transport and diffusive transport

  16. Local competition and metapopulation processes drive long-term seagrass-epiphyte population dynamics.

    PubMed

    Lobelle, Delphine; Kenyon, Emma J; Cook, Kevan J; Bull, James C

    2013-01-01

    It is well known that ecological processes such as population regulation and natural enemy interactions potentially occur over a range of spatial scales, and there is a substantial body of literature developing theoretical understanding of the interplay between these processes. However, there are comparatively few studies quantifying the long-term effects of spatial scaling in natural ecosystems. A key challenge is that trophic complexity in real-world biological communities quickly obscures the signal from a focal process. Seagrass meadows provide an excellent opportunity in this respect: in many instances, seagrasses effectively form extensive natural monocultures, in which hypotheses about endogenous dynamics can be formulated and tested. We present amongst the longest unbroken, spatially explict time series of seagrass abundance published to date. Data include annual measures of shoot density, total above-ground abundance, and associated epiphyte cover from five Zostera marina meadows distributed around the Isles of Scilly, UK, from 1996 to 2011. We explore empirical patterns at the local and metapopulation scale using standard time series analysis and develop a simple population dynamic model, testing the hypothesis that both local and metapopulation scale feedback processes are important. We find little evidence of an interaction between scales in seagrass dynamics but that both scales contribute approximately equally to observed local epiphyte abundance. By quantifying the long-term dynamics of seagrass-epiphyte interactions we show how measures of density and extent are both important in establishing baseline information relevant to predicting responses to environmental change and developing management plans. We hope that this study complements existing mechanistic studies of physiology, genetics and productivity in seagrass, whilst highlighting the potential of seagrass as a model ecosystem. More generally, this study provides a rare opportunity to test

  17. Seagrasses are negatively affected by organic matter loading and Arenicola marina activity in a laboratory experiment.

    PubMed

    Govers, Laura L; Pieck, Timon; Bouma, Tjeerd J; Suykerbuyk, Wouter; Smolders, Alfons J P; van Katwijk, Marieke M

    2014-06-01

    When two ecosystem engineers share the same natural environment, the outcome of their interaction will be unclear if they have contrasting habitat-modifying effects (e.g., sediment stabilization vs. sediment destabilization). The outcome of the interaction may depend on local environmental conditions such as season or sediment type, which may affect the extent and type of habitat modification by the ecosystem engineers involved. We mechanistically studied the interaction between the sediment-stabilizing seagrass Zostera noltii and the bioturbating and sediment-destabilizing lugworm Arenicola marina, which sometimes co-occur for prolonged periods. We investigated (1) if the negative sediment destabilization effect of A. marina on Z. noltii might be counteracted by positive biogeochemical effects of bioirrigation (burrow flushing) by A. marina in sulfide-rich sediments, and (2) if previously observed nutrient release by A. marina bioirrigation could affect seagrasses. We tested the individual and combined effects of A. marina presence and high porewater sulfide concentrations (induced by organic matter addition) on seagrass biomass in a full factorial lab experiment. Contrary to our expectations, we did not find an effect of A. marina on porewater sulfide concentrations. A. marina activities affected the seagrass physically as well as by pumping nutrients, mainly ammonium and phosphate, from the porewater to the surface water, which promoted epiphyte growth on seagrass leaves in our experimental set-up. We conclude that A. marina bioirrigation did not alleviate sulfide stress to seagrasses. Instead, we found synergistic negative effects of the presence of A. marina and high sediment sulfide levels on seagrass biomass.

  18. Introduction to Bed Bugs

    EPA Pesticide Factsheets

    The common bed bug (Cimex lectularius) is a pest – feeding on blood, causing itchy bites and generally irritating their human hosts. EPA and other agencies all consider bed bugs a public health pest, but bed bugs are not known to transmit disease.

  19. Making a Bed

    ERIC Educational Resources Information Center

    Wexler, Anthony; Stein, Sherman

    2005-01-01

    The origins of this paper lay in making beds by putting pieces of plywood on a frame: If beds need to be 4 feet 6 inches by 6 feet 3 inches, and plywood comes in 4-foot by 8-foot sheets, how should one cut the plywood to minimize waste (and have stable beds)? The problem is of course generalized.

  20. Research Abstracts of 1980.

    DTIC Science & Technology

    1980-12-01

    ABSTRACTS OF 1980. 9 - DTIC ELECTEf ii S AN3O 1981j _NAVAL DISTRIBUTION SMT:MIT DENTAL RESEARCH Approved for PUbDiC T INSTITE iii~2 YA3 It81 Naval...Medical Research apd Development Command 30 £ Bethesda, Maryland ( *- i - NTIS - GRA&I DTIC TAB - Urrannouneed NAVAL DENTAL RESEARCH INSTITUTE...r1 w American Assoctat/ion for Dental Research, 58th Annual Session, Los Angeles, California, March 20-23, 1980. 1. AV6ERSON*, D. N., LANGELAND, K

  1. Research Abstracts of 1979.

    DTIC Science & Technology

    1979-12-01

    7 AD-AO82 309 NAVAL DENTAL RESEARCH INST GREAT LAKES IL F/6 6/9 RESCH ABTAT79 991 UNCLASSIFIED NORI-PR-79-11 NL ’NDRI-PR 79-11 December 1979...RESEARCH ABSTRACTS OF 1979 OTICSELZCreD MAR 2?718 S A NAVAL DENTAL RESEARCH INSTITUTE Naval Medical Research and Development Command Bethesda, Maryland...8G 3 23 O4ൌ p.,. ... ....-- - I -- - ’.... .I l l ---,, .. . = ., , ." .;’.- I 1 IV NAVAL DENTAL RESEARCH INSTITUTE NAVAL BASE, BLDG. I-H GREAT LAKES

  2. Temporal pattern in biometrics and nutrient stoichiometry of the intertidal seagrass Zostera japonica and its adaptation to air exposure in a temperate marine lagoon (China): Implications for restoration and management.

    PubMed

    Zhang, Xiaomei; Zhou, Yi; Liu, Peng; Wang, Feng; Liu, Bingjian; Liu, Xujia; Yang, Hongsheng

    2015-05-15

    In coastal areas of China, the seagrass Zostera japonica has drastically decreased in the past decades. Swan Lake is an exception, where we found extensive areas of Z. japonica beds. The growth of Z. japonica in the lagoon exhibited strong seasonal variation. The maximum shoot density of 9880±2786 shoots m(-2) occurred in August. The maximum specific growth rate (SGR) of 4.99±1.99%⋅d(-1) was recorded in June 2012. SGR might be a good parameter for assessing the growth status of Z. japonica population. N and P contents in the rhizome were significantly lower than those in the leaf and leaf sheath. Lower C/P ratios suggested P enrichment of the seagrass. The occurrence of Z. japonica in Swan Lake was featured by adapting to the intertidal harsh environments. The transplantation method using sectioned rhizomes would be a potential way for restoration of degraded Z. japonica beds. The establishment of the Rongcheng Swan National Nature Reserve in China has contributed to the survival and expansion of Z. japonica in Swan Lake.

  3. Variability of the carbonate chemistry in a shallow, seagrass-dominated ecosystem: implications for ocean acidification experiments

    USGS Publications Warehouse

    Challener, Roberta; Robbins, Lisa L.; Mcclintock, James B.

    2016-01-01

    Open ocean observations have shown that increasing levels of anthropogenically derived atmospheric CO2 are causing acidification of the world's oceans. Yet little is known about coastal acidification and studies are just beginning to characterise the carbonate chemistry of shallow, nearshore zones where many ecologically and economically important organisms occur. We characterised the carbonate chemistry of seawater within an area dominated by seagrass beds (Saint Joseph Bay, Florida) to determine the extent of variation in pH and pCO2 over monthly and daily timescales. Distinct diel and seasonal fluctuations were observed at daily and monthly timescales respectively, indicating the influence of photosynthetic and respiratory processes on the local carbonate chemistry. Over the course of a year, the range in monthly values of pH (7.36-8.28), aragonite saturation state (0.65-5.63), and calculated pCO2 (195-2537 μatm) were significant. When sampled on a daily basis the range in pH (7.70-8.06), aragonite saturation state (1.86-3.85), and calculated pCO2 (379-1019 μatm) also exhibited significant range and indicated variation between timescales. The results of this study have significant implications for the design of ocean acidification experiments where nearshore species are utilised and indicate that coastal species are experiencing far greater fluctuations in carbonate chemistry than previously thought.

  4. Patterns of Abundance of Seagrasses and Associated Infaunal Communities at Inhaca Island, Mozambique

    NASA Astrophysics Data System (ADS)

    Paula, J.; Fidalgo Ecosta, P.; Martins, A.; Gove, D.

    2001-09-01

    This study was conducted at Inhaca Island, south Mozambique, and focused on three different seagrass associations, dominated respectively by Thalassodendron ciliatum, Thalassia hemprichii and Zostera capensis. The main objective of this study was to compare the three seagrass associations, in what concerns vegetal and associated infaunal communities biomass. The approach was a nested design, which intended to provide information on seasonal effects and variability at decreasing spatial scales. Nested ANOVA was performed for all biological and porewater parameters and a cluster analysis of different biotic and abiotic parameters was performed. Nutrient concentration was consistently higher during the dry period as well as mean values of organic matter. Consistently lower values of chlorophyll a (chl a) were obtained at T. hemprichii meadow sites and the highest values were found at Z. capensis meadow. Phaeopigments have shown an opposite pattern when compared to chl a, and average values were consistently higher during the dry season. There were no net differences of seagrass standing crop during both sampled seasons, however at meadow level major differences were found, and higher biomass was obtained at T. ciliatum meadow, followed by T. hemprichii. Mean values of epibiota have shown that higher biomass was obtained at T. ciliatum meadow, the remaining meadows presented very low values. Meiofauna biomass showed fluctuations between seagrass meadows, stations and also between seasons. Macrofauna biomass showed clear fluctuations between seasons, being strongly more homogeneous during the dry season and highly variable in the wet season. ANOVA results have shown different significance at the different levels of the analysis, suggesting different spatial and temporal patterns and interactions between parameters. The dendrogram produced two main groups of variables, the first one comprised of OM, phaeopigments, nitrites, nitrates, meiofauna, grain size and chl a. The

  5. Processes affecting the spatial distribution of seagrass meadow sedimentary material on Yao Yai Island, Thailand

    NASA Astrophysics Data System (ADS)

    Quak, Michelle S. Y.; Ziegler, Alan D.; Benner, Shawn G.; Evans, Sam; Todd, Peter A.; Gillis, Lucy G.; Vongtanaboon, Sukanya; Jachowski, Nick; Bouma, Tjeerd J.

    2016-12-01

    Many islands throughout SE Asia are experiencing rapid development and land-cover conversion that potentially threaten sensitive coastal ecosystems, such as seagrasses, through increased loading of sediment and nutrients originating from disturbed catchments draining to the sea. To evaluate this threat for one such island in Southern Thailand (Yao Yai), we perform sediment source tracing via end-member mixing analysis using stable isotopes δ13C and δ15N in organic matter to explore sediment loading in a seagrass meadow. The analysis indicates that sedimentary material in the meadow originates mostly from ocean-associated sources (∼62% from seagrass detritus, seston, and ocean sediments). Terrestrial material comprises ∼19% of the organic material found in the seagrass meadow, with another 20% originating from an adjacent mangrove forest. Approximately one-fourth of the seagrass meadow material (24%) is detritus that has been (re)deposited internally. The high contribution of terrestrial-derived organic matter deposited near the river mouth demonstrates that substantial quantities of sediment are being transferred from upslope erosion sources into the seagrass meadow. However, only a small amount of this material is deposited throughout the entire bay because much of the terrestrial- and mangrove-derived sediment is transferred to the open ocean via channels that are periodically dredged to allow boat access to two small inland harbours. This positive affect of dredging has not received very much attention in existing literature. River water flowing to the channels during falling tide delivers sediment to these efficient pathways, where much of it bypasses the seagrass meadow at periods of time when sediment deposition would normally be the greatest. There is growing concern that ongoing land-cover changes and planned urbanization related to tourism and agriculture on the island may boost sediment/nutrients above a critical threshold, beyond that revealed in

  6. Importance of seagrass as a carbon source for heterotrophic bacteria in a subtropical estuary (Florida Bay)

    NASA Astrophysics Data System (ADS)

    Williams, Clayton J.; Jaffé, Rudolf; Anderson, William T.; Jochem, Frank J.

    2009-11-01

    A stable carbon isotope approach was taken to identify potential organic matter sources incorporated into biomass by the heterotrophic bacterial community of Florida Bay, a subtropical estuary with a recent history of seagrass loss and phytoplankton blooms. To gain a more complete understanding of bacterial carbon cycling in seagrass estuaries, this study focused on the importance of seagrass-derived organic matter to pelagic, seagrass epiphytic, and sediment surface bacteria. Particulate organic matter (POM), seagrass epiphytic, seagrass ( Thalassia testudinum) leaf, and sediment surface samples were collected from four Florida Bay locations with historically different organic matter inputs, macrophyte densities, and primary productivities. Bulk (observed and those reported previously) and compound-specific bacterial fatty acid δ 13C values were used to determine important carbon sources to the estuary and benthic and pelagic heterotrophic bacteria. The δ 13C values of T. testudinum green leaves with epiphytes removed ranged from -9.9 to -6.9‰. Thalassia testudinum δ 13C values were significant more enriched in 13C than POM, epiphytic, and sediment samples, which ranged from -16.4 to -13.5, -16.2 to -9.6, and -16.7 to -11.0‰, respectively. Bacterial fatty acid δ 13C values (measured for br14:0, 15:0, i15:0, a15:0, br17:0, and 17:0) ranged from -25.5 to -8.2‰. Assuming a -3‰ carbon source fractionation from fatty acid to whole bacteria, pelagic, epiphytic, and sediment bacterial δ 13C values were generally more depleted in 13C than T. testudinum δ 13C values, more enriched in 13C than reported δ 13C values for mangroves, and similar to reported δ 13C values for algae. IsoSource mixing model results indicated that organic matter derived from T. testudinum was incorporated by both benthic and pelagic bacterial communities, where 13-67% of bacterial δ 13C values could arise from consumption of seagrass-derived organic matter. The IsoSource model

  7. The effect of oyster aquaculture on seagrass (Zostera marina) at the estuarine landscape scale in Willapa Bay, Washington (USA)

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Both seagrasses and bivalve shellfish provide valuable ecosystem services including nursery habitat in estuaries worldwide. Seagrasses are protected by no-net-loss provisions in US federal and state regulations resulting in a precautionary approach by managers that avoids any direct impacts from d...

  8. The Great Barrier Reef World Heritage Area seagrasses: Managing this iconic Australian ecosystem resource for the future

    NASA Astrophysics Data System (ADS)

    Coles, Robert G.; Rasheed, Michael A.; McKenzie, Len J.; Grech, Alana; York, Paul H.; Sheaves, Marcus; McKenna, Skye; Bryant, Catherine

    2015-02-01

    The Great Barrier Reef World Heritage Area (GBRWHA) includes one of the world's largest areas of seagrass (35,000 km2) encompassing approximately 20% of the world's species. Mapping and monitoring programs sponsored by the Australian and Queensland Governments and Queensland Port Authorities have tracked a worrying decrease in abundance and area since 2007. This decline has almost certainly been the result of a series of severe tropical storms and associated floods exacerbating existing human induced stressors. A complex variety of marine and terrestrial management actions and plans have been implemented to protect seagrass and other habitats in the GBRWHA. For seagrasses, these actions are inadequate. They provide an impression of effective protection of seagrasses; reduce the sense of urgency needed to trigger action; and waste the valuable and limited supply of "conservation capital". There is a management focus on ports, driven by public concerns about high profile development projects, which exaggerates the importance of these relatively concentrated impacts in comparison to the total range of threats and stressors. For effective management of seagrass at the scale of the GBRWHA, more emphasis needs to be placed on the connectivity between seagrass meadow health, watersheds, and all terrestrial urban and agricultural development associated with human populations. The cumulative impacts to seagrass from coastal and marine processes in the GBRWHA are not evenly distributed, with a mosaic of high and low vulnerability areas. This provides an opportunity to make choices for future coastal development plans that minimise stress on seagrass meadows.

  9. ROLE OF SEAGRASS (THALASSIA TESTUDINUM) AS A SOURCE OF CHROMOPHORIC DISSOLVED ORGANIC MATTER IN COASTAL SOUTH FLORIDA

    EPA Science Inventory

    Seagrasses play a variety of important ecological roles in coastal ecosystems. Here we present evidence that seagrass detritus from the widespread species, Thalassia testudinum, is an important source of ocean color and UV-protective substances in a low latitude coastal shelf re...

  10. Contrasting metabolic patterns among seagrass and sand-bottom habitats: relative roles of plankton and benthic metabolism

    EPA Science Inventory

    Human activities can alter the ecological function of estuaries, affecting the ecosystem metabolic balance, which in turn dictates the magnitude and mode of organic matter accumulation. Because human perturbations can cause a loss of seagrass habitat, seagrasses can be a sensitiv...

  11. MODELING THE DYNAMICS OF THREE FUNCTIONAL GROUPS OF MACROALGAE IN TROPICAL SEAGRASS HABITATS. (R828677C004)

    EPA Science Inventory

    A model of three functional groups of macroalgae, drift algae, rhizophytic calcareous algae, and seagrass epiphytes, was developed to complement an existing seagrass production model for tropical habitats dominated by Thalassia testudinum (Turtle-grass). The current modeling e...

  12. Effects of salinity on survival of the exotic seagrass Zostera japonica subjected to extreme high temperature stress

    EPA Science Inventory

    Zostera japonica is a non-indigenous seagrass that is expanding along the Pacific Coast of North America. The ecophysiology of this seagrass is poorly studied and management of the species is fragmented. We collected Z. japonica plants from Padilla Bay, WA., Yaquina Bay and Coo...

  13. Collaborative Strategy on Bed Bugs

    EPA Pesticide Factsheets

    The Collaborative Strategy on Bed Bugs was developed by the Federal Bed Bug Workgroup to clarify the federal role in bed bug control and highlight ways that government, community, academia and private industry can work together on bed bug issues.

  14. Landscape ecology of interactions between seagrass and mobile epifauna: The matrix matters

    NASA Astrophysics Data System (ADS)

    Tanner, Jason E.

    2006-07-01

    There is increasing interest among ecologists about how the type of matrix surrounding a habitat patch influences the organisms living in that patch. This question is virtually unstudied in marine systems. In this paper I show that the mobile faunal assemblage in seagrass patches does depend on the surrounding matrix. Faunal assemblages in patches of Posidonia surrounded by sand are different than in those surrounded by Heterozostera, another seagrass, having more than double the abundance of both amphipods and polychaetes. However, the differences are not simply due to spillover from the matrix habitat, but rather are an emergent property of the patch context that cannot be predicted. Posidonia surrounded by sand actually has an assemblage that is intermediate between Heterozostera and Posidonia surrounded by Heterozostera. Differences in habitat structure do not account for this pattern, as seagrass biomass did not vary, and the same result was found in artificial seagrass. The faunal assemblage did not vary depending on the location within the patch (edge or centre) for Heterozostera, Posidonia or artificial seagrass. Patch size, however, did have an effect for Heterozostera, with smaller patches having 2-3 times as many isopods per sample as large, but less than half the number of some amphipod families. These results suggest that the landscape context is as important in marine systems as it is known to be in terrestrial systems.

  15. Use of digital multispectral videography to assess seagrass distribution in San Quintin Bay, Baja California, Mexico

    USGS Publications Warehouse

    Ward, D.H.; Tibbitts, T.L.; Morton, Alexandra; Carrera-Gonzalez, Eduardo; Kempka, R.

    2004-01-01

    Apparent threats to the spatial distribution of seagrass in San Quintín Bay prompted us to make a detailed assessment of habitats in the bay. Six coastal habitats and three seagrass subclasses were delineated using airborne digital multispectral videography (DMSV). Eelgrass, Zostera marina, was the predominant seagrass and covered 40% (1949 ha) of the areal extent of the bay in 1999. Eelgrass grew over a wide range of tidal depths from about –3.0 m mean lower low water (MLLW) to about 1.0 m MLLW, but greatest spatial extent occurred in intertidal areas –0.6 m to 1.0 m MLLW. Exposed-continuous (i.e., high density) eelgrass was the most abundant habitat in the bay. Widgeongrass, Ruppia maritima, was the only other seagrass present and covered 3% (136 ha) of the areal extent of the entire bay. Widgeongrass grew in single species stands in the upper intertidal (≥ 0.4 MLLW) and intermixed with eelgrass at lower tidal depths. Overall accuracy of the six habitat classes and three subclasses in the DMSV map was relatively high at 84%. Our detailed map of San Quintín Bay can be used in future change detection analyses to monitor the health of seagrasses in the bay.

  16. Genome-wide survey of the seagrass Zostera muelleri suggests modification of the ethylene signalling network

    PubMed Central

    Golicz, Agnieszka A.; Schliep, Martin; Lee, Huey Tyng; Larkum, Anthony W.D.; Dolferus, Rudy; Batley, Jacqueline; Chan, Chon-Kit Kenneth; Sablok, Gaurav; Ralph, Peter J.; Edwards, David

    2015-01-01

    Seagrasses are flowering plants which grow fully submerged in the marine environment. They have evolved a range of adaptations to environmental challenges including light attenuation through water, the physical stress of wave action and tidal currents, high concentrations of salt, oxygen deficiency in marine sediment, and water-borne pollination. Although, seagrasses are a key stone species of the costal ecosystems, many questions regarding seagrass biology and evolution remain unanswered. Genome sequence data for the widespread Australian seagrass species Zostera muelleri were generated and the unassembled data were compared with the annotated genes of five sequenced plant species (Arabidopsis thaliana, Oryza sativa, Phoenix dactylifera, Musa acuminata, and Spirodela polyrhiza). Genes which are conserved between Z. muelleri and the five plant species were identified, together with genes that have been lost in Z. muelleri. The effect of gene loss on biological processes was assessed on the gene ontology classification level. Gene loss in Z. muelleri appears to influence some core biological processes such as ethylene biosynthesis. This study provides a foundation for further studies of seagrass evolution as well as the hormonal regulation of plant growth and development. PMID:25563969

  17. EBS Radionuclide Transport Abstraction

    SciTech Connect

    J.D. Schreiber

    2005-08-25

    The purpose of this report is to develop and analyze the engineered barrier system (EBS) radionuclide transport abstraction model, consistent with Level I and Level II model validation, as identified in ''Technical Work Plan for: Near-Field Environment and Transport: Engineered Barrier System: Radionuclide Transport Abstraction Model Report Integration'' (BSC 2005 [DIRS 173617]). The EBS radionuclide transport abstraction (or EBS RT Abstraction) is the conceptual model used in the total system performance assessment for the license application (TSPA-LA) to determine the rate of radionuclide releases from the EBS to the unsaturated zone (UZ). The EBS RT Abstraction conceptual model consists of two main components: a flow model and a transport model. Both models are developed mathematically from first principles in order to show explicitly what assumptions, simplifications, and approximations are incorporated into the models used in the TSPA-LA. The flow model defines the pathways for water flow in the EBS and specifies how the flow rate is computed in each pathway. Input to this model includes the seepage flux into a drift. The seepage flux is potentially split by the drip shield, with some (or all) of the flux being diverted by the drip shield and some passing through breaches in the drip shield that might result from corrosion or seismic damage. The flux through drip shield breaches is potentially split by the waste package, with some (or all) of the flux being diverted by the waste package and some passing through waste package breaches that might result from corrosion or seismic damage. Neither the drip shield nor the waste package survives an igneous intrusion, so the flux splitting submodel is not used in the igneous scenario class. The flow model is validated in an independent model validation technical review. The drip shield and waste package flux splitting algorithms are developed and validated using experimental data. The transport model considers

  18. Trophic implications and faunal resilience following one-off and successive disturbances to an Amphibolis griffithii seagrass system.

    PubMed

    Gartner, Adam; Lavery, Paul S; Lonzano-Montes, Hector

    2015-05-15

    Disturbances in seagrass systems often lead to considerable loss of seagrass fauna. We examined the capacity for seagrass fauna, across multiple trophic levels, to recover from disturbances, using empirical and modelling techniques. Model outputs, using Ecosim with Ecopath (EwE), were consistent with the results of field investigations, highlighting the models robustness. Modelled outcomes suggest second and third order consumers are likely to be negatively effected by disturbances in the seagrass canopy. Particularly piscivores, which once disturbed, appear unlikely to recover following severe declines in primary productivity. EwE also revealed the complex interaction between the duration and intensity of disturbances on seagrass fauna, which may differentially affect higher order consumers. Further, modelling predicted a variable capacity of higher order consumers to recover from successive disturbances, suggesting taxa with comparatively fast reproductive cycles and short generation terms would be more resilient than taxa with comparatively long generation terms and slow reproductive cycles.

  19. Towards adaptive management of the natural capital: Disentangling trade-offs among marine activities and seagrass meadows.

    PubMed

    Bas Ventín, Leticia; de Souza Troncoso, Jesús; Villasante, Sebastián

    2015-12-15

    This paper investigates the ecological, social and institutional dimensions of the synergies and trade-offs between seagrasses and human activities operating in the Natura 2000 protected site of San Simón Bay (Galicia, NW Spain). By means of a multidisciplinary approach that brings together the development of a biological inventory combined with participatory mapping processes we get key spatial and contextual understanding regarding how, where and why marine users interact with seagrasses and how seagrasses are considered in policy making. The results highlight the fisheries' reliance on seagrass meadows and the controversial links with shellfisheries. The study also reveals unresolved conflicts among those management plans that promote the protection of natural values and those responsible for the exploitation of marine resources. We conclude that the adoption of pre-planning bottom-up participatory processes is crucial for the design of realistic strategies where both seagrasses and human activities were considered as a couple system.

  20. Writing a successful research abstract.

    PubMed

    Bliss, Donna Z

    2012-01-01

    Writing and submitting a research abstract provides timely dissemination of the findings of a study and offers peer input for the subsequent development of a quality manuscript. Acceptance of abstracts is competitive. Understanding the expected content of an abstract, the abstract review process and tips for skillful writing will improve the chance of acceptance.

  1. Water quality in the Great Barrier Reef region: responses of mangrove, seagrass and macroalgal communities.

    PubMed

    Schaffelke, Britta; Mellors, Jane; Duke, Norman C

    2005-01-01

    Marine plants colonise several interconnected ecosystems in the Great Barrier Reef region including tidal wetlands, seagrass meadows and coral reefs. Water quality in some coastal areas is declining from human activities. Losses of mangrove and other tidal wetland communities are mostly the result of reclamation for coastal development of estuaries, e.g. for residential use, port infrastructure or marina development, and result in river bank destabilisation, deterioration of water clarity and loss of key coastal marine habitat. Coastal seagrass meadows are characterized by small ephemeral species. They are disturbed by increased turbidity after extreme flood events, but generally recover. There is no evidence of an overall seagrass decline or expansion. High nutrient and substrate availability and low grazing pressure on nearshore reefs have lead to changed benthic communities with high macroalgal abundance. Conservation and management of GBR macrophytes and their ecosystems is hampered by scarce ecological knowledge across macrophyte community types.

  2. The Genome of a Southern Hemisphere Seagrass Species (Zostera muelleri)1[OPEN

    PubMed Central

    Golicz, Agnieszka A.; Paterson, Andrew H.; Sablok, Gaurav; Krishnaraj, Rahul R.; Chan, Chon-Kit Kenneth; Batley, Jacqueline; Ralph, Peter J.

    2016-01-01

    Seagrasses are marine angiosperms that evolved from land plants but returned to the sea around 140 million years ago during the early evolution of monocotyledonous plants. They successfully adapted to abiotic stresses associated with growth in the marine environment, and today, seagrasses are distributed in coastal waters worldwide. Seagrass meadows are an important oceanic carbon sink and provide food and breeding grounds for diverse marine species. Here, we report the assembly and characterization of the Zostera muelleri genome, a southern hemisphere temperate species. Multiple genes were lost or modified in Z. muelleri compared with terrestrial or floating aquatic plants that are associated with their adaptation to life in the ocean. These include genes for hormone biosynthesis and signaling and cell wall catabolism. There is evidence of whole-genome duplication in Z. muelleri; however, an ancient pan-commelinid duplication event is absent, highlighting the early divergence of this species from the main monocot lineages. PMID:27373688

  3. Airborne Hyperspectral Imaging of Seagrass and Coral Reef

    NASA Astrophysics Data System (ADS)

    Merrill, J.; Pan, Z.; Mewes, T.; Herwitz, S.

    2013-12-01

    This talk presents the process of project preparation, airborne data collection, data pre-processing and comparative analysis of a series of airborne hyperspectral projects focused on the mapping of seagrass and coral reef communities in the Florida Keys. As part of a series of large collaborative projects funded by the NASA ROSES program and the Florida Fish and Wildlife Conservation Commission and administered by the NASA UAV Collaborative, a series of airborne hyperspectral datasets were collected over six sites in the Florida Keys in May 2012, October 2012 and May 2013 by Galileo Group, Inc. using a manned Cessna 172 and NASA's SIERRA Unmanned Aerial Vehicle. Precise solar and tidal data were used to calculate airborne collection parameters and develop flight plans designed to optimize data quality. Two independent Visible and Near-Infrared (VNIR) hyperspectral imaging systems covering 400-100nm were used to collect imagery over six Areas of Interest (AOIs). Multiple collections were performed over all sites across strict solar windows in the mornings and afternoons. Independently developed pre-processing algorithms were employed to radiometrically correct, synchronize and georectify individual flight lines which were then combined into color balanced mosaics for each Area of Interest. The use of two different hyperspectral sensor as well as environmental variations between each collection allow for the comparative analysis of data quality as well as the iterative refinement of flight planning and collection parameters.

  4. Seagrass meadows (Posidonia oceanica) distribution and trajectories of change

    PubMed Central

    Telesca, Luca; Belluscio, Andrea; Criscoli, Alessandro; Ardizzone, Giandomenico; Apostolaki, Eugenia T.; Fraschetti, Simonetta; Gristina, Michele; Knittweis, Leyla; Martin, Corinne S.; Pergent, Gérard; Alagna, Adriana; Badalamenti, Fabio; Garofalo, Germana; Gerakaris, Vasilis; Louise Pace, Marie; Pergent-Martini, Christine; Salomidi, Maria

    2015-01-01

    Posidonia oceanica meadows are declining at alarming rates due to climate change and human activities. Although P. oceanica is considered the most important and well-studied seagrass species of the Mediterranean Sea, to date there has been a limited effort to combine all the spatial information available and provide a complete distribution of meadows across the basin. The aim of this work is to provide a fine-scale assessment of (i) the current and historical known distribution of P. oceanica, (ii) the total area of meadows and (iii) the magnitude of regressive phenomena in the last decades. The outcomes showed the current spatial distribution of P. oceanica, covering a known area of 1,224,707 ha, and highlighted the lack of relevant data in part of the basin (21,471 linear km of coastline). The estimated regression of meadows amounted to 34% in the last 50 years, showing that this generalised phenomenon had to be mainly ascribed to cumulative effects of multiple local stressors. Our results highlighted the importance of enforcing surveys to assess the status and prioritize areas where cost-effective schemes for threats reduction, capable of reversing present patterns of change and ensuring P. oceanica persistence at Mediterranean scale, could be implemented. PMID:26216526

  5. Effects of tributyltin (TBT) on the seagrass Ruppia maritima.

    PubMed

    Jensen, H F; Holmer, M; Dahllöf, I

    2004-10-01

    The effects of tributyltin (TBT) on the seagrass Ruppia maritima were studied in two growth experiments. Plants were sampled at stations in Odense Fjord and Lunkebugten, Denmark, and replanted in reference sediment without TBT, reference sediment spiked with TBT, and in impacted sediment sampled in the highly TBT contaminated (7-57 microg kg (-1) dw) Odense Fjord. Plant performance was studied at weekly intervals for 3-4 weeks, by measuring net photosynthetic activity, respiration, relative growth rate (RGR) and number of leaves. Net photosynthetic activity in plants from spiked and impacted sediment was reduced by up to 60% relative to reference plants. Respiration both increased and decreased in response to TBT exposure, while RGR was generally lower in plants from contaminated sediments (reduced by 8-25%). The effects of spiked and impacted sediment differed between the experiments, which could be partly explained by the bioavailability of TBT in the two treatments, but also by adaptation of the plants from Odense Fjord to TBT. Measurements of enhanced TBT concentrations in the sediments in Odense Fjord suggest an impact of TBT on R. maritima is possible under in situ conditions.

  6. The Role of Seagrass Traits in Mediating Zostera noltei Vulnerability to Mesograzers

    PubMed Central

    Martínez-Crego, Begoña; Arteaga, Pedro; Tomas, Fiona; Santos, Rui

    2016-01-01

    Understanding how intra-specific differences in plant traits mediate vulnerability to herbivores of relevant habitat-forming plants is vital to attain a better knowledge on the drivers of the structure and functioning of ecosystems. Such studies, however, are rare in seagrass-mesograzer systems despite the increasingly recognized relevance of mesograzers as seagrass consumers. We investigated the role and potential trade-offs of multiple leaf traits in mediating the vulnerability of the seagrass Zostera noltei to different mesograzer species, the amphipod Gammarus insensibilis and the isopod Idotea chelipes. We worked with plants from two different meadows for which contrasting chemical and structural traits were expected based on previous information. We found that plants with high vulnerability to mesograzers (i.e. those preferred and subjected to higher rates of leaf area loss) had not only higher nitrogen content and lower C:N, fibre, and phenolics, but also tender and thinner leaves. No trade-offs between chemical and structural traits of the seagrass were detected, as they were positively correlated. When leaf physical structure was removed using agar-reconstituted food, amphipod preference towards high-susceptibility plants disappeared; thus indicating that structural rather than chemical traits mediated the feeding preference. Removal of plant structure reduced the size of isopod preference to less than half, indicating a stronger contribution of structural traits (> 50%) but combined with chemical/nutritional traits in mediating the preference. We then hypothesized that the high environmental nutrient levels recorded in the meadow exhibiting high susceptibility modulate the differences observed between meadows in seagrass traits. To test this hypothesis, we exposed low-vulnerability shoots to eutrophic nutrient levels in a 6-week enrichment experiment. Nutrient enrichment increased Z. noltei nitrogen content and lowered C:N, fibre, and phenolics, but had

  7. Remote influence of off-shore fish farm waste on Mediterranean seagrass (Posidonia oceanica) meadows.

    PubMed

    Ruiz, J M; Marco-Méndez, C; Sánchez-Lizaso, J L

    2010-04-01

    The aim of this study was estimating the remote influence of waste dispersed from a large off-shore fish farm complex (6197 ton year(-1)) on the near-shore Posidonia oceanica meadow (26-27 m deep) located at a distance of 3 km. Measurements of isotopic nitrogen content in epiphytes and seagrass leaf tissues, epiphyte biomass, shoot size, herbivory pressure, shoot density and seagrass meadow cover, performed in this meadow (FA area) were compared with those obtained in an undisturbed control meadow (CA area) to evaluate: (1) the remote influence of waste and (2) the impact of such influence on seagrass condition. In addition, delta(15)N measurements in particulate organic matter of natural and anthropogenic origin were used in a single-isotope mixing model to elucidate the relative contributions of these sources to the isotopic N signal measured in epiphytes and leaf tissues. Total tissue N content was similar between meadow areas, but delta(15)N signatures were significantly higher in the FA area than in the CA area both in epiphytes and seagrass leaf tissues. Results from the mixing model, together with available information on local currents and previous studies, support the conclusion that the dispersion of farm wastes over large areas (spanning kilometres) are responsible for the elevated delta(15)N signatures found in the FA meadow area. Despite this, no changes in meadow structure were detected and only some changes at the level of seagrass community (epiphytes abundances and herbivores activity) could be interpreted at the light of nutrient-induced effects in the FA area. Results from this study indicate that concentrating aquaculture facilities in off-shore areas is a strategy not totally exempt of environmental risk on near-shore sensitive habitats such as seagrass meadows.

  8. Seagrass Herbivory Levels Sustain Site-Fidelity in a Remnant Dugong Population

    PubMed Central

    Patankar, Vardhan; Marbà, Núria

    2015-01-01

    Herds of dugong, a largely tropical marine megaherbivore, are known to undertake long-distance movements, sequentially overgrazing seagrass meadows in their path. Given their drastic declines in many regions, it is unclear whether at lower densities, their grazing is less intense, reducing their need to travel between meadows. We studied the effect of the feeding behaviour of a small dugong population in the Andaman and Nicobar archipelago, India to understand how small isolated populations graze seagrasses. In the seven years of our observation, all recorded dugongs travelled either solitarily or in pairs, and their use of seagrasses was limited to 8 meadows, some of which were persistently grazed. These meadows were relatively large, contiguous and dominated by short-lived seagrasses species. Dugongs consumed approximately 15% of meadow primary production, but there was a large variation (3–40% of total meadow production) in consumption patterns between meadows. The impact of herbivory was relatively high, with shoot densities c. 50% higher inside herbivore exclosures than in areas exposed to repeated grazing. Our results indicate that dugongs in the study area repeatedly graze the same meadows probably because the proportion of primary production consumed reduces shoot density to levels that are still above values that can trigger meadow abandonment. This ability of seagrasses to cope perhaps explains the long-term site fidelity shown by individual dugongs in these meadows. The fact that seagrass meadows in the archipelago are able to support dugong foraging requirements allows us to clearly identify locations where this remnant population persists, and where urgent management efforts can be directed. PMID:26492558

  9. Chemoreception of the Seagrass Posidonia Oceanica by Benthic Invertebrates is Altered by Seawater Acidification.

    PubMed

    Zupo, Valerio; Maibam, Chingoileima; Buia, Maria Cristina; Gambi, Maria Cristina; Patti, Francesco Paolo; Scipione, Maria Beatrice; Lorenti, Maurizio; Fink, Patrick

    2015-08-01

    Several plants and invertebrates interact and communicate by means of volatile organic compounds (VOCs). These compounds may play the role of infochemicals, being able to carry complex information to selected species, thus mediating inter- or intra-specific communications. Volatile organic compounds derived from the wounding of marine diatoms, for example, carry information for several benthic and planktonic invertebrates. Although the ecological importance of VOCs has been demonstrated, both in terrestrial plants and in marine microalgae, their role as infochemicals has not been demonstrated in seagrasses. In addition, benthic communities, even the most complex and resilient, as those associated to seagrass meadows, are affected by ocean acidification at various levels. Therefore, the acidification of oceans could produce interference in the way seagrass-associated invertebrates recognize and choose their specific environments. We simulated the wounding of Posidonia oceanica leaves collected at two sites (a control site at normal pH, and a naturally acidified site) off the Island of Ischia (Gulf of Naples, Italy). We extracted the VOCs and tested a set of 13 species of associated invertebrates for their specific chemotactic responses in order to determine if: a) seagrasses produce VOCs playing the role of infochemicals, and b) their effects can be altered by seawater pH. Our results indicate that several invertebrates recognize the odor of wounded P. oceanica leaves, especially those strictly associated to the leaf stratum of the seagrass. Their chemotactic reactions may be modulated by the seawater pH, thus impairing the chemical communications in seagrass-associated communities in acidified conditions. In fact, 54% of the tested species exhibited a changed behavioral response in acidified waters (pH 7.7). Furthermore, the differences observed in the abundance of invertebrates, in natural vs. acidified field conditions, are in agreement with these behavioral

  10. Seagrass Herbivory Levels Sustain Site-Fidelity in a Remnant Dugong Population.

    PubMed

    D'Souza, Elrika; Patankar, Vardhan; Arthur, Rohan; Marbà, Núria; Alcoverro, Teresa

    2015-01-01

    Herds of dugong, a largely tropical marine megaherbivore, are known to undertake long-distance movements, sequentially overgrazing seagrass meadows in their path. Given their drastic declines in many regions, it is unclear whether at lower densities, their grazing is less intense, reducing their need to travel between meadows. We studied the effect of the feeding behaviour of a small dugong population in the Andaman and Nicobar archipelago, India to understand how small isolated populations graze seagrasses. In the seven years of our observation, all recorded dugongs travelled either solitarily or in pairs, and their use of seagrasses was limited to 8 meadows, some of which were persistently grazed. These meadows were relatively large, contiguous and dominated by short-lived seagrasses species. Dugongs consumed approximately 15% of meadow primary production, but there was a large variation (3-40% of total meadow production) in consumption patterns between meadows. The impact of herbivory was relatively high, with shoot densities c. 50% higher inside herbivore exclosures than in areas exposed to repeated grazing. Our results indicate that dugongs in the study area repeatedly graze the same meadows probably because the proportion of primary production consumed reduces shoot density to levels that are still above values that can trigger meadow abandonment. This ability of seagrasses to cope perhaps explains the long-term site fidelity shown by individual dugongs in these meadows. The fact that seagrass meadows in the archipelago are able to support dugong foraging requirements allows us to clearly identify locations where this remnant population persists, and where urgent management efforts can be directed.

  11. Nitrogen removal by anammox and denitrification in a subtropical seagrass ecosystem

    NASA Astrophysics Data System (ADS)

    Salk, K.; Ostrom, N. E.; Erler, D.; Eyre, B.; Carlson-Perret, N.

    2015-12-01

    Anammox is now recognized as a globally important process that may rival denitrification in its removal of inorganic N from aquatic systems. Owing to its fairly recent discovery, however, measurements of anammox in coastal environments are sparse. This study measured the N removal processes, denitrification and anammox, in a seagrass ecosystem in New South Wales, Australia, using a modified version of the isotope pairing technique. This previously published method has yet to be applied to seagrass environments and relies on the measurement of both N2O and N2 to calculate rates of anammox and denitrification. Intact sediment cores were incubated under in situ conditions and amended with 15N-NO3- as a tracer. The role of organic C quality in controlling N removal rates was evaluated through addition of seagrass or phytoplankton detritus. In control cores (i.e., no C addition), the total N removal rate was 0.48 ± 0.22 μmol N m-2 h-1. These are among the lowest rates measured in seagrasses and other coastal areas. N removal rates were stimulated when seagrass detritus was added (3.3 times higher than control) whereas the addition of phytoplankton detritus did not stimulate N removal. This is surprising, as phytoplankton detritus is generally a more labile C source than seagrass detritus. These results indicate that the microbial community responds more quickly to organic matter they are conditioned to process. Regardless of C treatment, anammox made up a greater proportion of N2 production (71 ± 16%) than denitrification (24 ± 13%), in contrast to most other studies. The high proportion of anammox-derived N2 production implies that previous N removal rates measured in other systems without anammox inclusion could be significantly underestimated.

  12. Fluidized bed combustor modeling

    NASA Technical Reports Server (NTRS)

    Horio, M.; Rengarajan, P.; Krishnan, R.; Wen, C. Y.

    1977-01-01

    A general mathematical model for the prediction of performance of a fluidized bed coal combustor (FBC) is developed. The basic elements of the model consist of: (1) hydrodynamics of gas and solids in the combustor; (2) description of gas and solids contacting pattern; (3) kinetics of combustion; and (4) absorption of SO2 by limestone in the bed. The model is capable of calculating the combustion efficiency, axial bed temperature profile, carbon hold-up in the bed, oxygen and SO2 concentrations in the bubble and emulsion phases, sulfur retention efficiency and particulate carry over by elutriation. The effects of bed geometry, excess air, location of heat transfer coils in the bed, calcium to sulfur ratio in the feeds, etc. are examined. The calculated results are compared with experimental data. Agreement between the calculated results and the observed data are satisfactory in most cases. Recommendations to enhance the accuracy of prediction of the model are suggested.

  13. The Seagrass Effect Turned Upside Down Changes the Prospective of Sea Urchin Survival and Landscape Implications

    PubMed Central

    Farina, Simone; Guala, Ivan; Oliva, Silvia; Piazzi, Luigi; Pires da Silva, Rodrigo; Ceccherelli, Giulia

    2016-01-01

    Habitat structure plays an important mediating role in predator-prey interactions. However the effects are strongly dependent on regional predator pools, which can drive predation risk in habitats with very similar structure in opposite directions. In the Mediterranean Sea predation on juvenile sea urchins is commonly known to be regulated by seagrass structure. In this study we test whether the possibility for juvenile Paracentrotus lividus to be predated changes in relation to the fragmentation of the seagrass Posidonia oceanica (four habitat classes: continuous, low-fragmentation, high-fragmentation and rocks), and to the spatial arrangement of such habitat classes at a landscape scale. Sea urchin predation risk was measured in a 20-day field experiment on tethered individuals placed in three square areas 35×35 m2 in size. Variability of both landscape and habitat structural attributes was assessed at the sampling grain 5×5 m2. Predation risk changed among landscapes, as it was lower where more ‘rocks’, and thus less seagrass, were present. The higher risk was found in the ‘continuous’ P. oceanica rather than in the low-fragmentation, high-fragmentation and rock habitats (p-values = 0.0149, 0.00008, and 0.0001, respectively). Therefore, the expectation that juvenile P. lividus survival would have been higher in the ‘continuous’ seagrass habitat, which would have served as shelter from high fish predation pressure, was not met. Predation risk changed across habitats due to different success between attack types: benthic attacks (mostly from whelks) were overall much more effective than those due to fish activity, the former type being associated with the ‘continuous’ seagrass habitat. Fish predation on juvenile sea urchins on rocks and ‘high-fragmentation’ habitat was less likely than benthic predation in the ‘continuous’ seagrass, with the low seagrass patch complexity increasing benthic activity. Future research should be aimed at

  14. Bathymetric Lidar Mapping of Seagrass Distribution within Redfish Bay State Scientific Area, Texas

    NASA Astrophysics Data System (ADS)

    Starek, M. J.; Fernandez-Diaz, J. C.; Singhania, A.; Shrestha, R. L.; Gibeaut, J. C.; Su, L.; Reisinger, A. S.; Lord, A.

    2013-05-01

    Monitoring seagrass habitat, species growth, and population decline is an important environmental initiative for coastal ecosystem sustainability. However, measuring details about seagrass distribution and canopy structure over large areas via remote sensing has proved challenging. Developments in airborne bathymetric light detection and ranging (lidar) provide great potential in this regard. Traditional bathymetric lidar systems have been limited in their ability to map within the shallow water zone (< 1 m) where seagrass is typically present due to limitations in receiver response and laser pulse length. Emergent short-pulse width bathymetric lidar sensors and waveform processing algorithms enable depth measurements in shallow water environments not previously accessible. This 3D information of the benthic layer can be applied to extract metrics about the seagrass canopy. On September 10, 2012, researchers with the National Center for Airborne Laser Mapping (NCALM) at the University of Houston (UH) and the Coastal and Marine Geospatial Sciences Lab (CMGL) of the Harte Research Institute at Texas A&M University-Corpus Christi conducted a coordinated airborne and ground-based survey of the Redfish Bay State Scientific Area as part of a collaborative study to investigate the capabilities of bathymetric lidar and hyperspectral imaging for seagrass mapping (standalone and in-fusion). Redfish Bay, located along the middle Texas coast of the Gulf of Mexico, is a state scientific area designated for the purposes of protecting and studying the native seagrasses. For this survey, UH acquired high resolution (2.5 shots/m^2) very-shallow water bathymetry data using their new lidar system , the Optech Aquarius Green (532 nm) system. In a separate flight, UH collected 2 sets of hyperspectral imaging data (1.2-m pixel resolution and 72 bands, and 0.6m pixel resolution and 36 bands) with their CASI 1500 hy sensor. For this survey the sensors were mounted on a PA-31 Chieftain

  15. The Seagrass Effect Turned Upside Down Changes the Prospective of Sea Urchin Survival and Landscape Implications.

    PubMed

    Farina, Simone; Guala, Ivan; Oliva, Silvia; Piazzi, Luigi; Pires da Silva, Rodrigo; Ceccherelli, Giulia

    2016-01-01

    Habitat structure plays an important mediating role in predator-prey interactions. However the effects are strongly dependent on regional predator pools, which can drive predation risk in habitats with very similar structure in opposite directions. In the Mediterranean Sea predation on juvenile sea urchins is commonly known to be regulated by seagrass structure. In this study we test whether the possibility for juvenile Paracentrotus lividus to be predated changes in relation to the fragmentation of the seagrass Posidonia oceanica (four habitat classes: continuous, low-fragmentation, high-fragmentation and rocks), and to the spatial arrangement of such habitat classes at a landscape scale. Sea urchin predation risk was measured in a 20-day field experiment on tethered individuals placed in three square areas 35×35 m2 in size. Variability of both landscape and habitat structural attributes was assessed at the sampling grain 5×5 m2. Predation risk changed among landscapes, as it was lower where more 'rocks', and thus less seagrass, were present. The higher risk was found in the 'continuous' P. oceanica rather than in the low-fragmentation, high-fragmentation and rock habitats (p-values = 0.0149, 0.00008, and 0.0001, respectively). Therefore, the expectation that juvenile P. lividus survival would have been higher in the 'continuous' seagrass habitat, which would have served as shelter from high fish predation pressure, was not met. Predation risk changed across habitats due to different success between attack types: benthic attacks (mostly from whelks) were overall much more effective than those due to fish activity, the former type being associated with the 'continuous' seagrass habitat. Fish predation on juvenile sea urchins on rocks and 'high-fragmentation' habitat was less likely than benthic predation in the 'continuous' seagrass, with the low seagrass patch complexity increasing benthic activity. Future research should be aimed at investigating, derived from

  16. Sea urchin overgrazing of seagrasses: A review of current knowledge on causes, consequences, and management

    NASA Astrophysics Data System (ADS)

    Eklöf, J. S.; de la Torre-Castro, M.; Gullström, M.; Uku, J.; Muthiga, N.; Lyimo, T.; Bandeira, S. O.

    2008-09-01

    Sea urchins are one of the most common seagrass macro-grazers in contemporary seagrass systems. Occasionally their grazing rates exceed seagrass growth rates, a phenomenon sometimes referred to as overgrazing. Because of a reported increasing frequency of overgrazing events, concomitant with loss of seagrass-associated ecosystem services, it has been suggested that overgrazing is one of the key threats to tropical and subtropical seagrasses. In light of this, we review the current knowledge on causes, consequences, and management of sea urchin overgrazing of seagrasses. Initially we argue that the definition of overgrazing must include scale and impairment of ecosystem services, since this is the de facto definition used in the literature, and will highlight the potential societal costs of seagrass overgrazing. A review of 16 identified cases suggests that urchin overgrazing is a global phenomenon, ranging from temperate to tropical coastal waters and involving at least 11 seagrass and 7 urchin species. Even though most overgrazing events seem to affect areas of <0.5 km 2, and recovery often occurs within a few years, overgrazing can have a range of large, long-term indirect effects such as loss of associated fauna and decreased sediment stabilization. A range of drivers behind overgrazing have been suggested, including bottom-up (nutrient enrichment), top-down (reduced predation control due to e.g. overfishing), "side-in" mechanisms (e.g. changes in water temperature) and natural population fluctuations. Based on recent studies, there seems to be fairly strong support for the top-down and bottom-up hypotheses. However, many potential drivers often co-occur and interact, especially in areas with high anthropogenic pressure, suggesting that multiple disturbances—by simultaneously reducing predation control, increasing urchin recruitment and reducing the resistance of seagrasses—could pave the way for overgrazing. In management, the most common response to

  17. Automated Supernova Discovery (Abstract)

    NASA Astrophysics Data System (ADS)

    Post, R. S.

    2015-12-01

    (Abstract only) We are developing a system of robotic telescopes for automatic recognition of Supernovas as well as other transient events in collaboration with the Puckett Supernova Search Team. At the SAS2014 meeting, the discovery program, SNARE, was first described. Since then, it has been continuously improved to handle searches under a wide variety of atmospheric conditions. Currently, two telescopes are used to build a reference library while searching for PSN with a partial library. Since data is taken every night without clouds, we must deal with varying atmospheric and high background illumination from the moon. Software is configured to identify a PSN, reshoot for verification with options to change the run plan to acquire photometric or spectrographic data. The telescopes are 24-inch CDK24, with Alta U230 cameras, one in CA and one in NM. Images and run plans are sent between sites so the CA telescope can search while photometry is done in NM. Our goal is to find bright PSNs with magnitude 17.5 or less which is the limit of our planned spectroscopy. We present results from our first automated PSN discoveries and plans for PSN data acquisition.

  18. Exoplanets and Multiverses (Abstract)

    NASA Astrophysics Data System (ADS)

    Trimble, V.

    2016-12-01

    (Abstract only) To the ancients, the Earth was the Universe, of a size to be crossed by a god in a day, by boat or chariot, and by humans in a lifetime. Thus an exoplanet would have been a multiverse. The ideas gradually separated over centuries, with gradual acceptance of a sun-centered solar system, the stars as suns likely to have their own planets, other galaxies beyond the Milky Way, and so forth. And whenever the community divided between "just one' of anything versus "many," the "manies" have won. Discoveries beginning in 1991 and 1995 have gradually led to a battalion or two of planets orbiting other stars, very few like our own little family, and to moderately serious consideration of even larger numbers of other universes, again very few like our own. I'm betting, however, on habitable (though not necessarily inhabited) exoplanets to be found, and habitable (though again not necessarily inhabited) universes. Only the former will yield pretty pictures.

  19. Stellar Presentations (Abstract)

    NASA Astrophysics Data System (ADS)

    Young, D.

    2015-12-01

    (Abstract only) The AAVSO is in the process of expanding its education, outreach and speakers bureau program. powerpoint presentations prepared for specific target audiences such as AAVSO members, educators, students, the general public, and Science Olympiad teams, coaches, event supervisors, and state directors will be available online for members to use. The presentations range from specific and general content relating to stellar evolution and variable stars to specific activities for a workshop environment. A presentation—even with a general topic—that works for high school students will not work for educators, Science Olympiad teams, or the general public. Each audience is unique and requires a different approach. The current environment necessitates presentations that are captivating for a younger generation that is embedded in a highly visual and sound-bite world of social media, twitter and U-Tube, and mobile devices. For educators, presentations and workshops for themselves and their students must support the Next Generation Science Standards (NGSS), the Common Core Content Standards, and the Science Technology, Engineering and Mathematics (STEM) initiative. Current best practices for developing relevant and engaging powerpoint presentations to deliver information to a variety of targeted audiences will be presented along with several examples.

  20. Abstraction of Drift Seepage

    SciTech Connect

    J.T. Birkholzer

    2004-11-01

    This model report documents the abstraction of drift seepage, conducted to provide seepage-relevant parameters and their probability distributions for use in Total System Performance Assessment for License Application (TSPA-LA). Drift seepage refers to the flow of liquid water into waste emplacement drifts. Water that seeps into drifts may contact waste packages and potentially mobilize radionuclides, and may result in advective transport of radionuclides through breached waste packages [''Risk Information to Support Prioritization of Performance Assessment Models'' (BSC 2003 [DIRS 168796], Section 3.3.2)]. The unsaturated rock layers overlying and hosting the repository form a natural barrier that reduces the amount of water entering emplacement drifts by natural subsurface processes. For example, drift seepage is limited by the capillary barrier forming at the drift crown, which decreases or even eliminates water flow from the unsaturated fractured rock into the drift. During the first few hundred years after waste emplacement, when above-boiling rock temperatures will develop as a result of heat generated by the decay of the radioactive waste, vaporization of percolation water is an additional factor limiting seepage. Estimating the effectiveness of these natural barrier capabilities and predicting the amount of seepage into drifts is an important aspect of assessing the performance of the repository. The TSPA-LA therefore includes a seepage component that calculates the amount of seepage into drifts [''Total System Performance Assessment (TSPA) Model/Analysis for the License Application'' (BSC 2004 [DIRS 168504], Section 6.3.3.1)]. The TSPA-LA calculation is performed with a probabilistic approach that accounts for the spatial and temporal variability and inherent uncertainty of seepage-relevant properties and processes. Results are used for subsequent TSPA-LA components that may handle, for example, waste package corrosion or radionuclide transport.

  1. Geographic variability in organic carbon stock and accumulation rate in sediments of East and Southeast Asian seagrass meadows

    NASA Astrophysics Data System (ADS)

    Miyajima, Toshihiro; Hori, Masakazu; Hamaguchi, Masami; Shimabukuro, Hiromori; Adachi, Hiroshi; Yamano, Hiroya; Nakaoka, Masahiro

    2015-04-01

    Organic carbon (OC) stored in the sediments of seagrass meadows has been considered a globally significant OC reservoir. However, the sparsity and regional bias of studies on long-term OC accumulation in coastal sediments have limited reliable estimation of the capacity of seagrass meadows as a global OC sink. We evaluated the amount and accumulation rate of OC in sediment of seagrass meadows and adjacent areas in East and Southeast Asia. In temperate sites, the average OC concentration in the top 30 cm of sediment was higher in seagrass meadows (780-1080 mmol g-1) than in sediments without seagrass cover (52-430 mmol g-1). The average OC in the top 30 cm of subtropical and tropical seagrass meadow sediments ranged from 140 to 440 mmol g-1. Carbon isotope mass balancing suggested that the contribution of seagrass-derived carbon to OC stored in sediments was often relatively minor (temperate: 10-40%; subtropical: 35-82%; tropical: 4-34%) and correlated to the habitat type, being particularly low in estuarine habitats. Stock of OC in the top meter of sediment of all the studied meadows ranged from 38 to 120 Mg ha-1. The sediment accumulation rates were estimated by radiocarbon dating of six selected cores (0.32-1.34 mm yr-1). The long-term OC accumulation rates calculated from the sediment accumulation rate and the top 30 cm average OC concentration for the seagrass meadows (24-101 kg ha-1 yr-1) were considerably lower than the OC accumulation rates previously reported for Mediterranean Posidonia oceanica meadows (580 kg ha-1 yr-1 on average). Current estimates for the global carbon sink capacity of seagrass meadows, which rely largely on Mediterranean studies, may be considerable overestimations.

  2. Error, Power, and Blind Sentinels: The Statistics of Seagrass Monitoring

    PubMed Central

    Schultz, Stewart T.; Kruschel, Claudia; Bakran-Petricioli, Tatjana; Petricioli, Donat

    2015-01-01

    We derive statistical properties of standard methods for monitoring of habitat cover worldwide, and criticize them in the context of mandated seagrass monitoring programs, as exemplified by Posidonia oceanica in the Mediterranean Sea. We report the novel result that cartographic methods with non-trivial classification errors are generally incapable of reliably detecting habitat cover losses less than about 30 to 50%, and the field labor required to increase their precision can be orders of magnitude higher than that required to estimate habitat loss directly in a field campaign. We derive a universal utility threshold of classification error in habitat maps that represents the minimum habitat map accuracy above which direct methods are superior. Widespread government reliance on blind-sentinel methods for monitoring seafloor can obscure the gradual and currently ongoing losses of benthic resources until the time has long passed for meaningful management intervention. We find two classes of methods with very high statistical power for detecting small habitat cover losses: 1) fixed-plot direct methods, which are over 100 times as efficient as direct random-plot methods in a variable habitat mosaic; and 2) remote methods with very low classification error such as geospatial underwater videography, which is an emerging, low-cost, non-destructive method for documenting small changes at millimeter visual resolution. General adoption of these methods and their further development will require a fundamental cultural change in conservation and management bodies towards the recognition and promotion of requirements of minimal statistical power and precision in the development of international goals for monitoring these valuable resources and the ecological services they provide. PMID:26367863

  3. Fluidized-bed boilers

    SciTech Connect

    Makansi, J.; Schwieger, B.

    1982-08-01

    This report reviews the current state of atmospheric fluidized-bed combustion. The fundamentals of fluidized-bed combustion and design considerations are first discussed. Tables provide details of manufacturers, worldwide, and of the boilers now installed. Eight plants in various countries and burning a variety of fuels, are described more fully.

  4. Fluidized bed calciner apparatus

    DOEpatents

    Owen, Thomas J.; Klem, Jr., Michael J.; Cash, Robert J.

    1988-01-01

    An apparatus for remotely calcining a slurry or solution feed stream of toxic or hazardous material, such as ammonium diurante slurry or uranyl nitrate solution, is disclosed. The calcining apparatus includes a vertical substantially cylindrical inner shell disposed in a vertical substantially cylindrical outer shell, in which inner shell is disposed a fluidized bed comprising the feed stream material to be calcined and spherical beads to aid in heat transfer. Extending through the outer and inner shells is a feed nozzle for delivering feed material or a cleaning chemical to the beads. Disposed in and extending across the lower portion of the inner shell and upstream of the fluidized bed is a support member for supporting the fluidized bed, the support member having uniform slots for directing uniform gas flow to the fluidized bed from a fluidizing gas orifice disposed upstream of the support member. Disposed in the lower portion of the inner shell are a plurality of internal electric resistance heaters for heating the fluidized bed. Disposed circumferentially about the outside length of the inner shell are a plurality of external heaters for heating the inner shell thereby heating the fluidized bed. Further, connected to the internal and external heaters is a means for maintaining the fluidized bed temperature to within plus or minus approximately 25.degree. C. of a predetermined bed temperature. Disposed about the external heaters is the outer shell for providing radiative heat reflection back to the inner shell.

  5. Bed Bugs FAQs

    MedlinePlus

    ... allow them to fit into the smallest of spaces and stay there for long periods of time, even without a blood meal. Bed bugs are usually transported from place to place as people travel. The bed bugs travel in the seams and ...

  6. FPGA Based Reconfigurable ATM Switch Test Bed

    NASA Technical Reports Server (NTRS)

    Chu, Pong P.; Jones, Robert E.

    1998-01-01

    Various issues associated with "FPGA Based Reconfigurable ATM Switch Test Bed" are presented in viewgraph form. Specific topics include: 1) Network performance evaluation; 2) traditional approaches; 3) software simulation; 4) hardware emulation; 5) test bed highlights; 6) design environment; 7) test bed architecture; 8) abstract sheared-memory switch; 9) detailed switch diagram; 10) traffic generator; 11) data collection circuit and user interface; 12) initial results; and 13) the following conclusions: Advances in FPGA make hardware emulation feasible for performance evaluation, hardware emulation can provide several orders of magnitude speed-up over software simulation; due to the complexity of hardware synthesis process, development in emulation is much more difficult than simulation and requires knowledge in both networks and digital design.

  7. Science and Management of the Introduced Seagrass Zostera japonica in North America

    EPA Science Inventory

    Healthy seagrass is considered a prime indicator of estuarine ecosystem function. On the Pacific coast of North America, at least two congeners of Zostera occur: native Zostera marina, and introduced, Z. japonica. Z. japonica is considered “invasive” and therefore, ecologically...

  8. Seagrass responses to and recovery (?) from seven years of brown tide

    USGS Publications Warehouse

    Onuf, C.P.

    2000-01-01

    Most harmful algal blooms are relatively short, violent paroxysms to aquatic systems. The Texas brown tide was unique in its 7-year domination of upper Laguna Madre wherein it reduced light penetrating 1 m from 31 to 63% on an annual basis between June 1990 and May 1997. In response, seagrasses declined in biomass in deep areas for two years. Over the next three years, bare areas opened up in the deepest areas of the seagrass meadow and the outer seagrass boundary retreated landward. In the last two years of the brown tide, regression of the dominant species, Halodule wrightii, slowed and stopped, and Halophila engelmanni, a previously minor species, revegetated some areas. Subsequent to cessation of meadow retreat, water clarity improved to pre-brown tide levels, consistent with the hypothesis that regeneration of nutrients from retreating seagrass meadow may have been the source of the nutrient subsidy required to sustain the brown tide at high concentration. However, after a short interlude of clear water and Halodule recovery, a resurgence of the bloom occurred and areas of regrowth succumbed. Although human activities did not seem to be involved in initiation or persistence of the brown tide, nutrients brought in by runoff from agricultural lands may have contributed to the return of bloom conditions.

  9. Ion concentrations in seagrass: A comparison of results from field and controlled-environment studies

    NASA Astrophysics Data System (ADS)

    Garrote-Moreno, Aurora; Cambridge, Marion; Sánchez-Lizaso, Jose Luis

    2016-11-01

    Osmoregulation is essential for the survival of seagrasses in marine and hypersaline environments. The aim of this study was to examine ion concentrations of four seagrass species (Posidonia australis, P. sinuosa, Amphibolis antarctica and A. griffithii) after exposure to salinity changes. Plant fragments were placed in a series of aquaria at marine salinity (35) and, after one week of acclimation, exposed for 7 days to salinities between 20 and 70. Cl-, Na+ and total ion concentration increased with salinity in leaf tissue of the four seagrasses species. These results were compared with those of P. australis and A. antarctica samples collected at three locations at Shark Bay, Western Australia where higher salinities occurred, ranging from 46 to 51. Concentrations of K+ and Ca+2 were higher in seagrass tissues from Shark Bay than in those in aquarium trials. Cl-, Na+ and total ions in P. australis and A. antarctica from Shark Bay were lowest at the highest salinity location. The K+/Na+ ratio in the aquarium trials (under ambient conditions) was in the following order: A. antarctica = A. griffithii > P. australis > P. sinuosa and Ca+2/Na+ ratio was: A. antarctica = A. griffithii > P. sinuosa > P. australis. This species order indicates a physiological capacity to tolerate variation in salinity. Furthermore, these ratios were higher in the locality with highest salinity in Shark Bay, indicating acclimation and adaptation of ion concentrations to the salinity regime in the environment.

  10. Fungal Community Successions in Rhizosphere Sediment of Seagrasses Enhalus acoroides under PAHs Stress

    PubMed Central

    Ling, Juan; Zhang, Yanying; Wu, Meilin; Wang, Youshao; Dong, Junde; Jiang, Yufeng; Yang, Qingsong; Zeng, Siquan

    2015-01-01

    Seagrass meadows represent one of the highest productive marine ecosystems and are of great ecological and economic values. Recently, they have been confronted with worldwide decline. Fungi play important roles in sustaining the ecosystem health as degraders of polycyclic aromatic hydrocarbons (PAHs), but fewer studies have been conducted in seagrass ecosystems. Hence, we investigated the dynamic variations of the fungal community succession under PAH stress in rhizosphere sediment of seagrasses Enhalus acoroides in this study. Polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), quantitative PCR (qPCR) and a clone library have been employed to analyze the fungal community’s shifts. Sequencing results of DGGE and the clone library showed that the predominant species belong to phyla Ascomycota and Basidiomycota. The abundance of three groups decreased sharply over the incubation period, whereas they demonstrated different fungal diversity patterns. Both the exposure time and the PAH concentrations affected the microbial diversity as assessed by PCR-DGGE analysis. Redundancy analysis (RDA) indicated that significant factors driving community shifts were ammonium and pH (p < 0.05). Significant amounts of the variations (31.1%) were explained by pH and ammonium, illustrating that those two parameters were the most likely ones to influence or be influenced by the fungal communities’ changes. Investigation results also indicated that fungal communities in seagrass meadow were very sensitive to PAH-induced stress and may be used as potential indicators for the PAH contamination. PMID:26096007

  11. REMOTE SENSING OF SEAGRASS WITH AVIRIS AND HIGH ALTITUDE AERIAL PHOTOGRAPHY

    EPA Science Inventory

    On May 15,2002 AVIRlS (Advanced VisuaJ/lnfrared Imaging Spectrometer) data and high altitude aerial photographs were acquired tor coastal .waters from Cape Lookout to Oregon Inlet, North Carolina. The study encompasses extensive areas of seagrass, federally protected submersed, r...

  12. Utilizing Depth of Colonization of Seagrasses to Develop Numeric Water Quality Criteria for Florida Estuaries

    EPA Science Inventory

    US EPA is working with state and local partners in Florida to develop numeric water quality criteria to protect estuaries from nutrient pollution. Similar to other nutrient management programs in Florida, EPA is considering status of seagrass habitats as an indicator of biologic...

  13. Quantifying Seagrass Light Requirements Using an Algorithm to Spatially Resolve Depth of Colonization

    EPA Science Inventory

    The maximum depth of colonization (Zc) is a useful measure of seagrass growth that describes response to light attenuation in the water column. However, lack of standardization among methods for estimating Zc has limited the description of habitat requirements at spatial scales m...

  14. Nitrate fertilisation does not enhance CO2 responses in two tropical seagrass species

    PubMed Central

    Ow, Y. X.; Vogel, N.; Collier, C. J.; Holtum, J. A. M.; Flores, F.; Uthicke, S.

    2016-01-01

    Seagrasses are often considered “winners” of ocean acidification (OA); however, seagrass productivity responses to OA could be limited by nitrogen availability, since nitrogen-derived metabolites are required for carbon assimilation. We tested nitrogen uptake and assimilation, photosynthesis, growth, and carbon allocation responses of the tropical seagrasses Halodule uninervis and Thalassia hemprichii to OA scenarios (428, 734 and 1213 μatm pCO2) under two nutrients levels (0.3 and 1.9 μM NO3−). Net primary production (measured as oxygen production) and growth in H. uninervis increased with pCO2 enrichment, but were not affected by nitrate enrichment. However, nitrate enrichment reduced whole plant respiration in H. uninervis. Net primary production and growth did not show significant changes with pCO2 or nitrate by the end of the experiment (24 d) in T. hemprichii. However, nitrate incorporation in T. hemprichii was higher with nitrate enrichment. There was no evidence that nitrogen demand increased with pCO2 enrichment in either species. Contrary to our initial hypothesis, nutrient increases to levels approximating present day flood plumes only had small effects on metabolism. This study highlights that the paradigm of increased productivity of seagrasses under ocean acidification may not be valid for all species under all environmental conditions. PMID:26976685

  15. CARBON AND NITROGEN ALLOCATION MODEL FOR THE SEAGRASS THALASSIA TESTUDUNUM IN LOWER LAGUNA MADRE

    EPA Science Inventory

    Inverse modeling methods are a powerful tool for understanding complex physiological relationships between seagrasses and their environment. The power of the method is a result of using ranges of data in a system of constraints to describe the biological system, in this case, t...

  16. EFFECTS OF A COASTAL GOLF COMPLEX ON WATER QUALITY, PERIPHYTON, AND SEAGRASS.

    EPA Science Inventory

    The objective of this study was to determine the effects of a golf course complex on water quality, colonized periphyton and seagrass meadows in adjacent freshwater, near-coastal and wetland areas. The environmental impact of the recreational facility, which uses spray wastewater...

  17. Nitrate fertilisation does not enhance CO2 responses in two tropical seagrass species

    NASA Astrophysics Data System (ADS)

    Ow, Y. X.; Vogel, N.; Collier, C. J.; Holtum, J. A. M.; Flores, F.; Uthicke, S.

    2016-03-01

    Seagrasses are often considered “winners” of ocean acidification (OA); however, seagrass productivity responses to OA could be limited by nitrogen availability, since nitrogen-derived metabolites are required for carbon assimilation. We tested nitrogen uptake and assimilation, photosynthesis, growth, and carbon allocation responses of the tropical seagrasses Halodule uninervis and Thalassia hemprichii to OA scenarios (428, 734 and 1213 μatm pCO2) under two nutrients levels (0.3 and 1.9 μM NO3‑). Net primary production (measured as oxygen production) and growth in H. uninervis increased with pCO2 enrichment, but were not affected by nitrate enrichment. However, nitrate enrichment reduced whole plant respiration in H. uninervis. Net primary production and growth did not show significant changes with pCO2 or nitrate by the end of the experiment (24 d) in T. hemprichii. However, nitrate incorporation in T. hemprichii was higher with nitrate enrichment. There was no evidence that nitrogen demand increased with pCO2 enrichment in either species. Contrary to our initial hypothesis, nutrient increases to levels approximating present day flood plumes only had small effects on metabolism. This study highlights that the paradigm of increased productivity of seagrasses under ocean acidification may not be valid for all species under all environmental conditions.

  18. Quantifying the dispersal potential of seagrass vegetative fragments: A comparison of multiple subtropical species

    NASA Astrophysics Data System (ADS)

    Weatherall, E. J.; Jackson, E. L.; Hendry, R. A.; Campbell, M. L.

    2016-02-01

    Seagrass meadows are threatened by anthropogenic and natural disturbances on both a local and global scale. Understanding the potential for seagrasses to disperse, connecting populations separated by unsuitable habitat is important to assess the resilience of regional populations. This study investigated the relative dispersal potential of vegetative fragments of seagrass from five subtropical species (Zostera muelleri, Halodule uninervis, Halophila ovalis, Halophila spinulosa, Halophila decipiens). Five questions were examined: 1) do vegetative fragments of different species settle at different velocities; 2) does a species morphometric variables influence settling velocities; 3) is a species settling velocity related to the species local distribution; 4) does temperature stress affect settling velocity; and 5) what is the composition and potential viability of seagrass fragments floating in the bay. A proportional distribution index for each species was determined using data from a habitat prediction model. It was found that H. spinulosa settled significantly faster than the remaining species and Z. muelleri settled the slowest. Variables influencing settling velocity included rhizome length, weight and surface area. In both Z. muelleri and H. ovalis settling velocities were significantly greater at higher temperatures (although there was no significant difference between approximately 5 and 10 °C above ambient temperature). H. uninervis was not significantly influenced by temperature. There was a significant negative correlation between species settling velocities and their distribution.

  19. Waves in Seagrass Systems: Review and Technical Recommendations

    DTIC Science & Technology

    2006-11-01

    T. Terawaki. 1998. Relationship between Zostera marina beds and bottom sediments, wave action offshore in Naruto , southern Japan (original title... Naruto chisaki ni okeru amamo-ba to teishitsu oyobi haro tono kankei). Fisheries Engineering (Japan)/Suisan Kogaku (Japan) 34:299-304. Dean, R. G

  20. Using abstract language signals power.

    PubMed

    Wakslak, Cheryl J; Smith, Pamela K; Han, Albert

    2014-07-01

    Power can be gained through appearances: People who exhibit behavioral signals of power are often treated in a way that allows them to actually achieve such power (Ridgeway, Berger, & Smith, 1985; Smith & Galinsky, 2010). In the current article, we examine power signals within interpersonal communication, exploring whether use of concrete versus abstract language is seen as a signal of power. Because power activates abstraction (e.g., Smith & Trope, 2006), perceivers may expect higher power individuals to speak more abstractly and therefore will infer that speakers who use more abstract language have a higher degree of power. Across a variety of contexts and conversational subjects in 7 experiments, participants perceived respondents as more powerful when they used more abstract language (vs. more concrete language). Abstract language use appears to affect perceived power because it seems to reflect both a willingness to judge and a general style of abstract thinking.

  1. Turning patients over in bed

    MedlinePlus

    Roll patients in bed ... following steps should be followed: Explain to the patient what you are planning to do so the ... Stand on the side of the bed the patient will be turning towards and lower the bed ...

  2. Distribution and stability of eelgrass beds at Izembek Lagoon, Alaska

    USGS Publications Warehouse

    Ward, David H.; Markon, Carl J.; Douglas, David C.

    1997-01-01

    Spatial change in eelgrass meadows, Zostera marina L., was assessed between 1978 and 1987 and between 1987 and 1995 at Izembek Lagoon, Alaska. Change in total extent was evaluated through a map to map comparison of data interpreted from a 1978 Landsat multi-spectral scanner image and 1987 black and white aerial photographs. A ground survey in 1995 was used to assess spatial change from 1987. Eelgrass beds were the predominant vegetation type in the lagoon, comprising 44-47% (15000-16000 ha) of the total area in 1978 and 1987. Izembek Lagoon contains the largest bed of seagrass along the Pacific Coast of North America and largest known single stand of eelgrass in the world. There was a high degree of overlap in the spatial distribution of eelgrass among years of change detection. The overall net change was a 6% gain between, 1978 and 1987 and a <1% gain between 1987 and 1995. The lack of significant change in eelgrass cover suggests that eelgrass meadows in Izembek Lagoon have been stable during the 17-year period of our study.

  3. Evidence of Season-Dependency in Vegetation Effects on Macrofauna in Temperate Seagrass Meadows (Baltic Sea)

    PubMed Central

    Włodarska-Kowalczuk, Maria; Jankowska, Emilia; Kotwicki, Lech; Balazy, Piotr

    2014-01-01

    Seagrasses and associated macrophytes are important components of coastal systems as ecosystem engineers, habitat formers, and providers of food and shelter for other organisms. The positive impacts of seagrass vegetation on zoobenthic abundance and diversity (as compared to bare sands) are well documented, but only in surveys performed in summer, which is the season of maximum canopy development. Here we present the results of the first study of the relationship between the seasonal variability of seagrass vegetation and persistence and magnitude of contrasts in faunal communities between vegetated and bare sediments. The composition, abundance, biomass, and diversity of macrozoobenthos in both habitats were compared five times throughout the year in temperate eelgrass meadows in the southern Baltic Sea. Significant positive effects of macrophyte cover on invertebrate density and biomass were recorded only in June, July, and October when the seagrass canopy was relatively well developed. The effects of vegetation cover on faunal species richness, diversity, and composition persisted throughout the year, but the magnitude of these effects varied seasonally and followed changes in macrophyte biomass. The strongest effects were observed in July and coincided with maximums in seagrass biomass and the diversity and biomass of other macrophytes. These observations indicate that in temperate, clearly seasonal systems the assessment of macrophyte impact cannot be based solely on observations performed in just one season, especially when that season is the one in which macrophyte growth is at its maximum. The widely held belief that macrophyte cover strongly influences benthic fauna in marine coastal habitats, which is based on summer surveys, should be revisited and complemented with information obtained in other seasons. PMID:25000560

  4. Seagrass dynamics in shallow coastal lagoons: Interactions with fluid dynamics, sediment resuspension and light conditions

    NASA Astrophysics Data System (ADS)

    Carr, J. A.; D'Odorico, P.; McGlathery, K.; Wiberg, P. L.

    2010-12-01

    Sea grasses have been recognized for their ability to stabilize the benthic sediments of shallow coastal lagoons, thereby reducing the turbidity of the water column and providing a light environment that is more favorable for sea grass establishment and growth. Sea grasses are complex, in that they involve different strategies of carbon allocation between below and above ground biomass, and the partitioning of the overall biomass into a discrete number of stems and leaves. Stem density and canopy height, in turn, modify the flow field, sediment resuspension, and the light environment. It is still unclear how these seasonal and interannual dynamics of seagrass vegetation may be affected by and interact with the process of sediment resuspension under fluctuating climatic and hydrologic conditions. To this end, a coupled model hydrodynamic model of vegetation-sediment-water flow interactions and vegetation growth is developed and used to examine the feedback between seagrass vegetation density and sediment resuspension and water column turbidity. The daily growth model is designed to capture underground biomass and the growth and senescence of above ground biomass structural components (e.g., leaves and stems). This allows for investigating how the interseasonal and seasonal variability in shoot and leaf density within a meadow affects the strength of positive feedback between seagrass and their light environment. Eight years of hourly wind, light, tides and water temperature are used to drive the coupled model from an initial mature meadow state as well as a seedling state. The model demonstrates both the emergence of bistable behavior as well as the limited resilience of seagrass meadows due to the strength of the positive feedback. The effects of increased water depths and water temperatures on the health and resilience of a seagrass meadow were also investigated. As both water depth and water temperatures increase, the system only exhibits bistable behavior with

  5. Responses of seagrass to anthropogenic and natural disturbances do not equally translate to its consumers.

    PubMed

    Tomas, Fiona; Martínez-Crego, Begoña; Hernán, Gema; Santos, Rui

    2015-11-01

    Coastal communities are under threat from many and often co-occurring local (e.g., pollution, eutrophication) and global stressors (e.g., climate change), yet understanding the interactive and cumulative impacts of multiple stressors in ecosystem function is far from being accomplished. Ecological redundancy may be key for ecosystem resilience, but there are still many gaps in our understanding of interspecific differences within a functional group, particularly regarding response diversity, that is, whether members of a functional group respond equally or differently to anthropogenic stressors. Herbivores are critical in determining plant community structure and the transfer of energy up the food web. Human disturbances may alter the ecological role of herbivory by modifying the defense strategies of plants and thus the feeding patterns and performance of herbivores. We conducted a suite of experiments to examine the independent and interactive effects of anthropogenic (nutrient and CO2 additions) and natural (simulated herbivory) disturbances on a seagrass and its interaction with two common generalist consumers to understand how multiple disturbances can impact both a foundation species and a key ecological function (herbivory) and to assess the potential existence of response diversity to anthropogenic and natural changes in these systems. While all three disturbances modified seagrass defense traits, there were contrasting responses of herbivores to such plant changes. Both CO2 and nutrient additions influenced herbivore feeding behavior, yet while sea urchins preferred nutrient-enriched seagrass tissue (regardless of other experimental treatments), isopods were deterred by these same plant tissues. In contrast, carbon enrichment deterred sea urchins and attracted isopods, while simulated herbivory only influenced isopod feeding choice. These contrasting responses of herbivores to disturbance-induced changes in seagrass help to better understand the ecological

  6. Production and consumption of tropical seagrass fields in Eastern Indonesia measured with bell jars and microelectrodes

    NASA Astrophysics Data System (ADS)

    Lindeboom, H. J.; Sandee, A. J. J.

    During the Indonesian-Dutch Snellius-II Expedition the production and consumption of tropical seagrass species were measured with bell jars at four sampling stations in eastern Indonesia. Applying a conversion factor of 0.29, the amount of carbon fixed and mineralized was calculated from the recorded oxygen evolution. The gross production of the different seagrass communities was found to be between 1230 and 4700 mg C·m -2·d -1. The consumption lay between 860 and 3860 mg C·m -2·d -1. From these data a relatively low net production of 60 to 1060 mg C·m -2· -1 could be calculated. At one sampling station incubations were carried out at different depths in a sloping Halodule uninervis (Forssk.) Aschers meadow, which indicated that seagrasses above a depth of about 2 m may become subject to photoinhibition. A linear correlation between biomass and measured production was found for Thalassia hemprichii (Ehrenb.) Aschers. Above a biomass of 100 g DW·m -2 the production per unit of biomass decreased due to self shading. Using microelectrodes the oxygen production of epiphytes was found to be 230 mg C·m -2 leaf surface·d -1. at 1900 μE·m -2·s -1 assuming an epiphyte coverage of 40%. This indicated that up to 36% of the primary production in a seagrass community may be attributed to epiphytes. The seagrass fields in Indonesia were found to be healthy ecosystems with a high primary production, but organisms within the communities use the abundance of organic matter very efficiently, creating net production rates of 100 to 300 mg C·m -2·d -1 which are similar to barren areas.

  7. Loading and Unloading Finishing Pigs: Effects of Bedding Types, Ramp Angle, and Bedding Moisture

    PubMed Central

    Garcia, Arlene; McGlone, John J.

    2014-01-01

    Simple Summary Current guidelines suggest the use of ramps below 20 degrees to load and unload pigs; however, they do not suggest the use of any specific bedding. Bedding types (nothing, feed, sand, wood shavings, and hay) were tested with finishing pigs (70–120 kg) to determine which was most effective in reducing slips, falls, and vocalizations at three ramp angles, two moisture levels, over two seasons. Slips, falls, and vocalizations were summed to establish a scoring system for the types of beddings. Heart rate and the total time it took to load and unload pigs, increased as the slope increased. Bedding, bedding moisture, season, and ramp slope interacted to impact the total time it took for finishing pigs to load and unload the ramp. Selection of the best bedding depends on ramp slope, season, and wetness of bedding. Abstract The use of non-slip surfaces during loading and unloading of finishing pigs plays an important role in animal welfare and economics of the pork industry. Currently, the guidelines available only suggest the use of ramps with a slope below 20 degrees to load and unload pigs. However, the total time it takes to load and unload animals and slips, falls, and vocalizations are a welfare concern. Three ramp angles (0, 10 or 20 degrees), five bedding materials (nothing, sand, feed, wood shavings or wheat straw hay), two moistures (dry or wet bedding, >50% moisture) over two seasons (>23.9 °C summer, <23.9 °C winter) were assessed for slips/falls/vocalizations (n = 2400 pig observations) and analyzed with a scoring system. The use of bedding during summer or winter played a role in the total time it took to load and unload the ramp (p < 0.05). Bedding, bedding moisture, season, and slope significantly interacted to impact the total time to load and unload finishing pigs (p < 0.05). Heart rate and the total time it took to load and unload the ramp increased as the slope of the ramp increased (p < 0.05). Heart rates were higher during the

  8. Grounding Abstractness: Abstract Concepts and the Activation of the Mouth.

    PubMed

    Borghi, Anna M; Zarcone, Edoardo

    2016-01-01

    One key issue for theories of cognition is how abstract concepts, such as freedom, are represented. According to the WAT (Words As social Tools) proposal, abstract concepts activate both sensorimotor and linguistic/social information, and their acquisition modality involves the linguistic experience more than the acquisition of concrete concepts. We report an experiment in which participants were presented with abstract and concrete definitions followed by concrete and abstract target-words. When the definition and the word matched, participants were required to press a key, either with the hand or with the mouth. Response times and accuracy were recorded. As predicted, we found that abstract definitions and abstract words yielded slower responses and more errors compared to concrete definitions and concrete words. More crucially, there was an interaction between the target-words and the effector used to respond (hand, mouth). While responses with the mouth were overall slower, the advantage of the hand over the mouth responses was more marked with concrete than with abstract concepts. The results are in keeping with grounded and embodied theories of cognition and support the WAT proposal, according to which abstract concepts evoke linguistic-social information, hence activate the mouth. The mechanisms underlying the mouth activation with abstract concepts (re-enactment of acquisition experience, or re-explanation of the word meaning, possibly through inner talk) are discussed. To our knowledge this is the first behavioral study demonstrating with real words that the advantage of the hand over the mouth is more marked with concrete than with abstract concepts, likely because of the activation of linguistic information with abstract concepts.

  9. Grounding Abstractness: Abstract Concepts and the Activation of the Mouth

    PubMed Central

    Borghi, Anna M.; Zarcone, Edoardo

    2016-01-01

    One key issue for theories of cognition is how abstract concepts, such as freedom, are represented. According to the WAT (Words As social Tools) proposal, abstract concepts activate both sensorimotor and linguistic/social information, and their acquisition modality involves the linguistic experience more than the acquisition of concrete concepts. We report an experiment in which participants were presented with abstract and concrete definitions followed by concrete and abstract target-words. When the definition and the word matched, participants were required to press a key, either with the hand or with the mouth. Response times and accuracy were recorded. As predicted, we found that abstract definitions and abstract words yielded slower responses and more errors compared to concrete definitions and concrete words. More crucially, there was an interaction between the target-words and the effector used to respond (hand, mouth). While responses with the mouth were overall slower, the advantage of the hand over the mouth responses was more marked with concrete than with abstract concepts. The results are in keeping with grounded and embodied theories of cognition and support the WAT proposal, according to which abstract concepts evoke linguistic-social information, hence activate the mouth. The mechanisms underlying the mouth activation with abstract concepts (re-enactment of acquisition experience, or re-explanation of the word meaning, possibly through inner talk) are discussed. To our knowledge this is the first behavioral study demonstrating with real words that the advantage of the hand over the mouth is more marked with concrete than with abstract concepts, likely because of the activation of linguistic information with abstract concepts. PMID:27777563

  10. Cultivation-dependent analysis of the microbial diversity associated with the seagrass meadows in Xincun Bay, South China Sea.

    PubMed

    Jiang, Yu-Feng; Ling, Juan; Wang, You-Shao; Chen, Biao; Zhang, Yan-Ying; Dong, Jun-De

    2015-10-01

    Microbial communities have largely existed in the seagrass meadows. A total of 496 strains of the bacteria in the seagrass meadows, which belonged to 50 genera, were obtained by the plate cultivation method from three sites of Xincun Bay, South China Sea. The results showed that Bacillales and Vibrionales accounted for the highest proportions of organisms in all communities. The diversity of the bacteria in the sediment was higher than that associated with seagrass. Thalassia hemperichii possessed the highest abundance of bacteria, followed by Enhalus acoroides and Cymodocea rotundata. Robust seasonal dynamics in microbial community composition were also observed. It was found that microbial activities were closely tied to the growth stage of the seagrass. The microbial distribution was the lowest in site 3. The abundance of the bacteria was linked to the interactions between bacteria and plants, the condition of plant and even the coastal water quality and the nutrition level in the sediment.

  11. Using MODIS data for mapping of water types within river plumes in the Great Barrier Reef, Australia: towards the production of river plume risk maps for reef and seagrass ecosystems.

    PubMed

    Petus, Caroline; da Silva, Eduardo Teixeira; Devlin, Michelle; Wenger, Amelia S; Alvarez-Romero, Jorge G

    2014-05-01

    River plumes are the major transport mechanism for nutrients, sediments and other land-based pollutants into the Great Barrier Reef (GBR, Australia) and are a major threat to coastal and marine ecosystems such as coral reefs and seagrass beds. Understanding the spatial extent, frequency of occurrence, loads and ecological impacts of land-based pollutants discharged through river plumes is essential to drive catchment management actions. In this study, a framework to produce river plume risk maps for seagrass and coral ecosystems, using supervised classification of MODIS Level 2 (L2) satellite products, is presented. Based on relevant L2 thresholds, river plumes are classified into Primary, Secondary, and Tertiary water types, which represent distinct water quality (WQ) parameters concentrations and combinations. Annual water type maps are produced over three wet seasons (2010-2013) as a case of study. These maps provide a synoptic basis to assess the likelihood and magnitude of the risk of reduced coastal WQ associated with the river discharge (river plume risk) and in combination with sound knowledge of the regional ecosystems can serve as the basis to assess potential ecological impacts for coastal and marine GBR ecosystems. The methods described herein provide relevant and easily reproducible large-scale information for river plume risk assessment and management.

  12. Mechanical Engineering Department technical abstracts

    SciTech Connect

    Denney, R.M.

    1982-07-01

    The Mechanical Engineering Department publishes listings of technical abstracts twice a year to inform readers of the broad range of technical activities in the Department, and to promote an exchange of ideas. Details of the work covered by an abstract may be obtained by contacting the author(s). Overall information about current activities of each of the Department's seven divisions precedes the technical abstracts.

  13. The ecological importance of the dwarf seagrass Zostera japonica in intertidal areas on the southern coast of Korea

    NASA Astrophysics Data System (ADS)

    Choi, Sun Kyeong; Kim, Sangil; Lee, Kun-Seop; Li, Wen-Tao; Park, Sang Rul

    2016-03-01

    The intertidal seagrass Zostera japonica, which is distributed in the intertidal and shallow subtidal zones, is exposed to nutrients from over-enriched land-based discharge and storm water runoff before they can be washed out to sea. Despite its ecological importance, only a few studies have examined the ecology and physiology of Z. japonica in northeast Asia. In this study, we investigated the productivity and tissue nutrient contents of above- and below-ground tissues to evaluate the potential role of Z. japonica in carbon capture and as a nutrient sink. The average total, above-, and below-ground productivity per shoot was 0.56, 0.34, and 0.21 mg DW shoot-1 day-1, respectively. Annual leaf production was 1.5 times higher than annual below-ground production. Estimated annual whole-plant carbon, nitrogen, and phosphorus incorporation based on shoot production and tissue nutrient contents was 312.8 g C m-2 y-1, 25.7 g N m-2 y-1, and 1.6 g P m-2 y-1, respectively. These values were equivalent to 7.8 × 103 kg C y-1, 6.4 × 102 kg N y-1, and 40 kg P y-1 for all Z. japonica beds in Geoje Bay. This suggests that Z. japonica meadows can incorporate a considerable amount of carbon, nitrogen, and phosphorus in the intertidal zone. High N:P ratios of above- and below-ground tissues suggest that Z. japonica growth is probably limited by phosphorus availability in the study area.

  14. A halocarbon survey from a seagrass dominated subtropical lagoon, Ria Formosa (Portugal): flux pattern and isotopic composition

    NASA Astrophysics Data System (ADS)

    Weinberg, I.; Bahlmann, E.; Eckhardt, T.; Michaelis, W.; Seifert, R.

    2014-07-01

    Here we report fluxes of chloromethane (CH3Cl), bromomethane (CH3Br), iodomethane (CH3Cl), and bromoform (CHBr3) from two sampling campaigns (summer and spring) in the seagrass dominated subtropical lagoon Ria Formosa, Portugal. Dynamic flux chamber measurements were performed when seagrass patches were air-exposed and submerged. Overall, we observed highly variable fluxes from the seagrass meadows and attributed them to diurnal cycles, tidal effects, and the variety of possible sources and sinks in the seagrass meadows. Highest emissions with up to 130 nmol m-2 h-1 for CH3Br were observed during tidal changes from air exposure to submergence and conversely. Furthermore, at least during the spring campaign, the emissions of halocarbons were significantly elevated during tidal inundation as compared to air exposure. Accompanying water sampling during both campaigns revealed elevated concentrations of CH3Cl and CH3Br indicating productive sources within the lagoon. Stable carbon isotopes of halocarbons from the air and water phase along with source signatures were used to allocate the distinctive sources and sinks in the lagoon. Results suggest CH3Cl rather originating from seagrass meadows and water column than from salt marshes. Aqueous and atmospheric CH3Br was substantially enriched in 13C in comparison to source signatures for seagrass meadows and salt marshes. This suggests a significant contribution of the water column to the atmospheric CH3Br in the lagoon. A rough global upscaling yields annual productions from seagrass meadows of 2.3-4.5 Gg yr-1, 0.5-1.0 Gg yr-1, 0.6-1.2 Gg yr-1, and 1.9-3.7 Gg yr-1 for CH3Cl, CH3Br, CH3I, and CHBr3 respectively. This suggests a minor contribution from seagrass meadows to the global production of these halocarbons with about 0.1% for CH3Cl and about 0.7% for CH3Br.

  15. Bed Bug Information Clearinghouse

    EPA Pesticide Factsheets

    Its purpose is to help states, communities, and consumers in efforts to prevent and control bed bug infestations. Currently includes only reviewed material from federal/state/local government agencies, extension services, and universities.

  16. Bed Bug Tips

    EPA Pesticide Factsheets

    How to deal with bed bugs in one printable page. Ten tips include ensuring correct insect identification, reducing clutter, understand integrated pest management, using mattress and box spring encasements, and heat treatment.

  17. Tapered bed bioreactor

    DOEpatents

    Scott, Charles D.; Hancher, Charles W.

    1977-01-01

    A vertically oriented conically shaped column is used as a fluidized bed bioreactor wherein biologically catalyzed reactions are conducted in a continuous manner. The column utilizes a packing material a support having attached thereto a biologically active catalytic material.

  18. Particle fuel bed tests

    SciTech Connect

    Horn, F.L.; Powell, J.R.; Savino, J.M.

    1985-01-01

    Gas-cooled reactors, using packed beds of small diameter coated fuel particles have been proposed for compact, high-power systems. The particulate fuel used in the tests was 800 microns in diameter, consisting of a thoria kernel coated with 200 microns of pyrocarbon. Typically, the bed of fuel particles was contained in a ceramic cylinder with porous metallic frits at each end. A dc voltage was applied to the metallic frits and the resulting electric current heated the bed. Heat was removed by passing coolant (helium or hydrogen) through the bed. Candidate frit materials, rhenium, nickel, zirconium carbide, and zirconium oxide were unaffected, while tungsten and tungsten-rhenium lost weight and strength. Zirconium-carbide particles were tested at 2000 K in H/sub 2/ for 12 hours with no visible reaction or weight loss.

  19. Moving-bed sorbents

    SciTech Connect

    Ayala, R.E.; Gupta, R.P.; Chuck, T.

    1995-12-01

    The objective of this program is to develop mixed-metal oxide sorbent formulations that are suitable for moving-bed, high-temperature, desulfurization of coal gas. Work continues on zinc titanates formulations and Z-sorb III sorbent.

  20. Are all abstracts created equal??

    PubMed

    Weinert, Clarann

    2010-05-01

    The preparation of a strong, convincing abstract is a necessary professional skill and prized art form for nurse scientists and clinical scholars. The power and the role of an abstract are often overlooked. Abstracts are used in a variety of scholarly forums including articles submitted for publication, research proposals, and responses to "calls for abstracts" for presentations at scientific conferences. The purpose of this article is to emphasize the highlights of the "art" rather than the "cookbook" details associated with preparing an abstract. Each of the critical stages of abstract development is explored-planning, drafting, reviewing, peer reviewing, editing, and packaging. Likewise, a few, hopefully helpful, hints on developing the six key elements-background, purpose, sample, methods, results, and implications-of the scientific abstract are given. Polishing, the essential skill of preparing an abstract, takes time and persistence and will pay off in the long run. The well-crafted abstract is an initial step in the process of getting research and scholarly pursuits noticed and accepted.

  1. Test Bed For Telerobots

    NASA Technical Reports Server (NTRS)

    Matijevic, Jacob R.; Zimmerman, Wayne F.; Dolinsky, Shlomo

    1990-01-01

    Assembly of electromechanical and electronic equipment (including computers) constitutes test bed for development of advanced robotic systems for remote manipulation. Combines features not found in commercial systems. Its architecture allows easy growth in complexity and level of automation. System national resource for validation of new telerobotic technology. Intended primarily for robots used in outer space, test bed adapted to development of advanced terrestrial telerobotic systems for handling radioactive materials, dangerous chemicals, and explosives.

  2. Bed exit alarms.

    PubMed

    2004-09-01

    Bed-exit alarms alert caregivers that a patient who should not get out of bed unassisted is doing so. These alarms can help reduce the likelihood of falls and can promote speedy assistance to patients who have already fallen. But as we described in our May 2004 Guidance Article on bed-exit alarms, they don't themselves prevent falls. They are only effective if used as part of an overall fall-prevention program and with a clear understanding of their limitations. This Evaluation examines the effectiveness of 16 bed-exit alarms from seven suppliers. Our ratings focus primarily on each product's reliability in detecting bed-exit events and alerting caregivers, its ability to minimize nuisance alarms (alarms that sound even though the patient isn't leaving the bed or that sound while a caregiver is helping the patient to leave the bed), and its resistance to deliberate or inadvertent tampering. Twelve of the products use pressure-sensor-activated alarms (mainly sensor pads placed on or under the mattress); three use a cord that can attach to the patient's garment, alarming if the cord is pulled loose from the control unit; and one is a position-sensitive alarm attached to a leg cuff. All the products reliably detect attempted or successful bed exits. But they vary greatly in how effectively they alert staff, minimize nuisance alarms, and resist tampering. Ease of use and battery performance also vary for many units. Of the pressure-sensor units, three are rated Preferred. Those units meet most of our criteria and have no significant disadvantages. Five of the other pressure-sensor products are Acceptable, and the remaining four are Not Recommended. All three cord-activated alarms are rated Acceptable, as is the patient-worn alarm.

  3. Seagrass Identification Using High-Resolution 532nm Bathymetric LiDAR and Hyperspectral Imagery

    NASA Astrophysics Data System (ADS)

    Pan, Z.; Prasad, S.; Starek, M. J.; Fernandez Diaz, J. C.; Glennie, C. L.; Carter, W. E.; Shrestha, R. L.; Singhania, A.; Gibeaut, J. C.

    2013-12-01

    Seagrass provides vital habitat for marine fisheries and is a key indicator species of coastal ecosystem vitality. Monitoring seagrass is therefore an important environmental initiative, but measuring details of seagrass distribution over large areas via remote sensing has proved challenging. Developments in airborne bathymetric light detection and ranging (LiDAR) provide great potential in this regard. Traditional bathymetric LiDAR systems have been limited in their ability to map within the shallow water zone (< 1 m) where seagrass is typically present due to limitations in receiver response and laser pulse length. Emergent short-pulse width bathymetric LiDAR sensors and waveform processing algorithms enable depth measurements in shallow water environments previously inaccessible. This 3D information of the benthic layer can be applied to detect seagrass and characterize its distribution. Researchers with the National Center for Airborne Laser Mapping (NCALM) at the University of Houston (UH) and the Coastal and Marine Geospatial Sciences Lab (CMGL) of the Harte Research Institute at Texas A&M University-Corpus Christi conducted a coordinated airborne and boat-based survey of the Redfish Bay State Scientific Area as part of a collaborative study to investigate the capabilities of bathymetric LiDAR and hyperspectral imaging for seagrass mapping. Redfish Bay, located along the middle Texas coast of the Gulf of Mexico, is a state scientific area designated for the purpose of protecting and studying native seagrasses. Redfish Bay is part of the broader Coastal Bend Bays estuary system recognized by the US Environmental Protection Agency (EPA) as a national estuary of significance. For this survey, UH acquired high-resolution discrete-return and full-waveform bathymetric data using their Optech Aquarius 532 nm green LiDAR. In a separate flight, UH collected 2 sets of hyperspectral imaging data (1.2-m pixel resolution and 72 bands, and 0.6m pixel resolution and 36

  4. Bed rest and immunity

    NASA Astrophysics Data System (ADS)

    Sonnenfeld, Gerald; Aviles, Hernan; Butel, Janet S.; Shearer, William T.; Niesel, David; Pandya, Utpal; Allen, Christopher; Ochs, Hans D.; Blancher, Antoine; Abbal, Michel

    2007-02-01

    Space flight has been shown to result in altered immune responses. The current study was designed to investigate this possibility by using the bed rest model of some space flight conditions. A large number of women are included as subjects in the study. The hypothesis being tested is: 60 days head-down tilt bed rest of humans will affect the immune system and resistance to infection. Blood, urine and saliva samples will be obtained from bed rest subjects prior to, at intervals during, and after completion of 60 days of head-down tilt bed rest. Leukocyte blastogenesis, cytokine production and virus reactivation will be assessed. The ability of the subjects to respond appropriately to immunization with the neoantigen bacteriophage φX-174 will also be determined. Bed rest is being carried out at MEDES, Toulouse France, and the University of Texas Medical Branch, Galveston, TX. The studies to be carried out in France will also allow assessment of the effects of muscle/bone exercise and nutritional countermeasures on the immune system in addition to the effects of bed rest.

  5. Resilience and stability of Cymodocea nodosa seagrass meadows over the last four decades in a Mediterranean lagoon

    NASA Astrophysics Data System (ADS)

    Garrido, Marie; Lafabrie, Céline; Torre, Franck; Fernandez, Catherine; Pasqualini, Vanina

    2013-09-01

    Understanding what controls the capacity of a coastal lagoon ecosystem to recover following climatic and anthropogenic perturbations and how these perturbations can alter this capacity is critical to efficient environmental management. The goal of this study was to examine the resilience and stability of Cymodocea nodosa-dominated seagrass meadows in Urbino lagoon (Corsica, Mediterranean Sea) by characterizing the spatio-temporal dynamics of seagrass meadows over a 40-year period and comparing (anthropogenic and climatic) environmental fluctuations. The spatio-temporal evolution of seagrass meadows was investigated using previous maps (1973, 1979, 1990, 1994, 1996, 1999) and a 2011 map realized by aerial photography-remote sensing combined with GIS technology. Environmental fluctuation was investigated via physical-chemical parameters (rainfall, water temperature, salinity, turbidity, dissolved oxygen) and human-impact changes (aquaculture, artificial channel). The results showed a severe decline (estimated at -49%) in seagrass meadows between 1973 and 1994 followed by a period of strong recovery (estimated to +42%) between 1994 and 2011. Increased turbidity, induced either by rainfall events, dredging or phytoplankton growth, emerged as the most important driver of the spatio-temporal evolution of Cymodocea nodosa-dominated meadows in Urbino lagoon over the last four decades. Climate events associated to increased turbidity and reduced salinity and temperature could heavily impact seagrass dynamics. This study shows that Urbino lagoon, a system relatively untouched by human impact, shelters seagrass meadows that exhibit high resilience and stability.

  6. Field data sets for seagrass biophysical properties for the Eastern Banks, Moreton Bay, Australia, 2004-2014

    NASA Astrophysics Data System (ADS)

    Roelfsema, Chris M.; Kovacs, Eva M.; Phinn, Stuart R.

    2015-08-01

    This paper describes seagrass species and percentage cover point-based field data sets derived from georeferenced photo transects. Annually or biannually over a ten year period (2004-2014) data sets were collected using 30-50 transects, 500-800 m in length distributed across a 142 km2 shallow, clear water seagrass habitat, the Eastern Banks, Moreton Bay, Australia. Each of the eight data sets include seagrass property information derived from approximately 3000 georeferenced, downward looking photographs captured at 2-4 m intervals along the transects. Photographs were manually interpreted to estimate seagrass species composition and percentage cover (Coral Point Count excel; CPCe). Understanding seagrass biology, ecology and dynamics for scientific and management purposes requires point-based data on species composition and cover. This data set, and the methods used to derive it are a globally unique example for seagrass ecological applications. It provides the basis for multiple further studies at this site, regional to global comparative studies, and, for the design of similar monitoring programs elsewhere.

  7. Field data sets for seagrass biophysical properties for the Eastern Banks, Moreton Bay, Australia, 2004–2014

    PubMed Central

    Roelfsema, Chris M.; Kovacs, Eva M.; Phinn, Stuart R.

    2015-01-01

    This paper describes seagrass species and percentage cover point-based field data sets derived from georeferenced photo transects. Annually or biannually over a ten year period (2004–2014) data sets were collected using 30–50 transects, 500–800 m in length distributed across a 142 km2 shallow, clear water seagrass habitat, the Eastern Banks, Moreton Bay, Australia. Each of the eight data sets include seagrass property information derived from approximately 3000 georeferenced, downward looking photographs captured at 2–4 m intervals along the transects. Photographs were manually interpreted to estimate seagrass species composition and percentage cover (Coral Point Count excel; CPCe). Understanding seagrass biology, ecology and dynamics for scientific and management purposes requires point-based data on species composition and cover. This data set, and the methods used to derive it are a globally unique example for seagrass ecological applications. It provides the basis for multiple further studies at this site, regional to global comparative studies, and, for the design of similar monitoring programs elsewhere. PMID:26396742

  8. Metabolomics Reveals Cryptic Interactive Effects of Species Interactions and Environmental Stress on Nitrogen and Sulfur Metabolism in Seagrass.

    PubMed

    Hasler-Sheetal, Harald; Castorani, Max C N; Glud, Ronnie N; Canfield, Donald E; Holmer, Marianne

    2016-11-01

    Eutrophication of estuaries and coastal seas is accelerating, increasing light stress on subtidal marine plants and changing their interactions with other species. To date, we have limited understanding of how such variations in environmental and biological stress modify the impact of interactions among foundational species and eventually affect ecosystem health. Here, we used metabolomics to assess the impact of light reductions on interactions between the seagrass Zostera marina, an important habitat-forming marine plant, and the abundant and commercially important blue mussel Mytilus edulis. Plant performance varied with light availability but was unaffected by the presence of mussels. Metabolomic analysis, on the other hand, revealed an interaction between light availability and presence of M. edulis on seagrass metabolism. Under high light, mussels stimulated seagrass nitrogen and energy metabolism. Conversely, in low light mussels impeded nitrogen and energy metabolism, and enhanced responses against sulfide toxicity, causing inhibited oxidative energy metabolism and tissue degradation. Metabolomic analysis thereby revealed cryptic changes to seagrass condition that could not be detected by traditional approaches. Our findings suggest that coastal eutrophication and associated reductions in light may shift seagrass-bivalve interactions from mutualistic to antagonistic, which is important for conservation management of seagrass meadows.

  9. Control of bed height in a fluidized bed gasification system

    DOEpatents

    Mehta, Gautam I.; Rogers, Lynn M.

    1983-12-20

    In a fluidized bed apparatus a method for controlling the height of the fdized bed, taking into account variations in the density of the bed. The method comprises taking simultaneous differential pressure measurements at different vertical elevations within the vessel, averaging the differential pressures, determining an average fluidized bed density, then periodically calculating a weighting factor. The weighting factor is used in the determination of the actual bed height which is used in controlling the fluidizing means.

  10. Leadership Abstracts; Volume 4, 1991.

    ERIC Educational Resources Information Center

    Doucette, Don, Ed.

    1991-01-01

    "Leadership Abstracts" is published bimonthly and distributed to the chief executive officer of every two-year college in the United States and Canada. This document consists of the 15 one-page abstracts published in 1991. Addressing a variety of topics of interest to the community college administrators, this volume includes: (1) "Delivering the…

  11. Innovation Abstracts, Volume XV, 1993.

    ERIC Educational Resources Information Center

    Roueche, Suanne D., Ed.

    1993-01-01

    This volume of 30 one- to two-page abstracts from 1993 highlights a variety of innovative approaches to teaching and learning in the community college. Topics covered in the abstracts include: (1) role-playing to encourage critical thinking; (2) team learning techniques to cultivate business skills; (3) librarian-instructor partnerships to create…

  12. Vague Language in Conference Abstracts

    ERIC Educational Resources Information Center

    Cutting, Joan

    2012-01-01

    This study examined abstracts for a British Association for Applied Linguistics conference and a Sociolinguistics Symposium, to define the genre of conference abstracts in terms of vague language, specifically universal general nouns (e.g. people) and research general nouns (e.g. results), and to discover if the language used reflected the level…

  13. Water quality, isoscapes and stoichioscapes of seagrasses indicate general P limitation and unique N cycling in shallow water benthos of Bermuda

    NASA Astrophysics Data System (ADS)

    Fourqurean, J. W.; Manuel, S. A.; Coates, K. A.; Kenworthy, W. J.; Boyer, J. N.

    2015-10-01

    Striking spatial patterns in stable isotope ratios (isoscapes) and elemental ratios (stoichioscapes) of seagrass leaves and the water column nutrients indicate general P-limitation of both water column and benthic primary productivity on the Bermuda Platform, and they highlight the role of the Bermuda Islands as a source of N and P. We found consistent differences among the four seagrass species (Syringodium filiforme, Thalassia testudinum, Halodule sp. and Halophila decipiens) in the N, P, δ13C and δ15N of leaf tissues. The δ15N of seagrass leaves was especially variable, with values from -10.1 to 8.8 ‰, greatly expanding the reported range of values for all seagrass species globally. Spatial patterns from both the water column and the seagrass leaves indicated that P availability was higher near shore, and δ15N values suggest this was likely a result of human waste disposal. Spatially contiguous areas of extremely depleted seagrass 15N suggest unique N sources and cycling compared to other seagrass-dominated environments. Seagrass N : P values were not as far from the stoichiometric balance between N and P availability as in the water column, and there were no strong relationships between the water column N : P and the seagrass N : P. Such isoscapes and stoichioscapes provide valuable ecogeochemical tools to infer ecosystem processes as well as provide information that can inform food web and animal movement studies.

  14. Water quality, isoscapes and stoichioscapes of seagrasses indicate general P limitation and unique N cycling in shallow water benthos of Bermuda

    NASA Astrophysics Data System (ADS)

    Fourqurean, J. W.; Manuel, S. A.; Coates, K. A.; Kenworthy, W. J.; Boyer, J. N.

    2015-07-01

    Striking spatial patterns in stable isotope ratios (isoscapes) and elemental ratios (stoichioscapes) of seagrass leaves and the water column nutrients indicate general P-limitation of both water column and benthic primary productivity on the Bermuda Platform, and they highlight the role of the Bermuda Islands as a source of N and P. We found consistent differences among the four seagrass species (Syringodium filiforme, Thalassia testudinum, Halodule sp. and Halophila decipiens) in the N, P, δ13C and δ15N of leaf tissues. The δ15N of seagrass leaves was especially variable, with values from -10.1 to 8.8‰, greatly expanding the reported range of values for all seagrass species globally. Spatial patterns from both the water column and the seagrass leaves indicated that P availability was higher near shore, and δ15N values suggest this was likely a result of human waste disposal. Spatially-contiguous areas of extremely depleted seagrass δ15N suggest unique N sources and cycling compared to other seagrass-dominated environments. Seagrass N : P values were not as far from the stoichiometric balance between N and P availability as in the water column, and there were no strong relationships between the water column N : P and the seagrass N : P. Such isoscapes and stoichioscapes provide valuable ecogeochemical tools to infer ecosystem processes as well as provide information that can inform food web and animal movement studies.

  15. 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

  16. Technical abstracts: Mechanical engineering, 1990

    SciTech Connect

    Broesius, J.Y.

    1991-03-01

    This document is a compilation of the published, unclassified abstracts produced by mechanical engineers at Lawrence Livermore National Laboratory (LLNL) during the calendar year 1990. Many abstracts summarize work completed and published in report form. These are UCRL-JC series documents, which include the full text of articles to be published in journals and of papers to be presented at meetings, and UCID reports, which are informal documents. Not all UCIDs contain abstracts: short summaries were generated when abstracts were not included. Technical Abstracts also provides descriptions of those documents assigned to the UCRL-MI (miscellaneous) category. These are generally viewgraphs or photographs presented at meetings. An author index is provided at the back of this volume for cross referencing.

  17. Stable isotope analyses reveal the importance of seagrass beds as feeding areas for juvenile Myrophic punctatus in Florida

    EPA Science Inventory

    The feeding habits and habitats of the speckled worm eel Myrophis punctatus were studied on the mangrove edge of the Indian River Lagoon (Florida) using stomach contents and stable isotope analyses of carbon (δ13C) and nitrogen (δ15N). Stomach dietary analyses identified four tax...

  18. Abstracts

    NASA Astrophysics Data System (ADS)

    2012-09-01

    Measuring cosmological parameters with GRBs: status and perspectives New interpretation of the Amati relation The SED Machine - a dedicated transient spectrograph PTF10iue - evidence for an internal engine in a unique Type Ic SN Direct evidence for the collapsar model of long gamma-ray bursts On pair instability supernovae and gamma-ray bursts Pan-STARRS1 observations of ultraluminous SNe The influence of rotation on the critical neutrino luminosity in core-collapse supernovae General relativistic magnetospheres of slowly rotating and oscillating neutron stars Host galaxies of short GRBs GRB 100418A: a bridge between GRB-associated hypernovae and SNe Two super-luminous SNe at z ~ 1.5 from the SNLS Prospects for very-high-energy gamma-ray bursts with the Cherenkov Telescope Array The dynamics and radiation of relativistic flows from massive stars The search for light echoes from the supernova explosion of 1181 AD The proto-magnetar model for gamma-ray bursts Stellar black holes at the dawn of the universe MAXI J0158-744: the discovery of a supersoft X-ray transient Wide-band spectra of magnetar burst emission Dust formation and evolution in envelope-stripped core-collapse supernovae The host galaxies of dark gamma-ray bursts Keck observations of 150 GRB host galaxies Search for properties of GRBs at large redshift The early emission from SNe Spectral properties of SN shock breakout MAXI observation of GRBs and short X-ray transients A three-dimensional view of SN 1987A using light echo spectroscopy X-ray study of the southern extension of the SNR Puppis A All-sky survey of short X-ray transients by MAXI GSC Development of the CALET gamma-ray burst monitor (CGBM)

  19. Abstracts

    ERIC Educational Resources Information Center

    Parsegian, V. L., Ed.

    1972-01-01

    Includes summaries of six articles dealing with engineering education, population management, blood sampling, international pollution control, environmental quality index, and scientific phases in political science. (CC)

  20. EPA-Registered Bed Bug Products

    MedlinePlus

    ... Pest Bed Bugs EPA Registered Bed Bug Products EPA-Registered Bed Bug Products Resources Bed Bug Main ... Bugs Tips Joint Statement on Bed Bug Control EPA has developed a search tool that can help ...

  1. Cross hospital bed management system.

    PubMed

    Abedian, S; Kazemi, H; Riazi, H; Bitaraf, E

    2014-01-01

    The lack of adequate numbers of hospital beds to accommodate the injured is a main problem in public hospitals. For control of occupancy of bed, we design a dynamic system that announces status of bed when it change with admission or discharge of a patient. This system provide a wide network in country for bed management, especially for ICU and CCU beds that help us to distribute injured patient in the hospitals.

  2. Spatial patterns of sub-tidal seagrasses and their tissue nutrients in the Torres Strait, northern Australia: Implications for management

    NASA Astrophysics Data System (ADS)

    Sheppard, James K.; Carter, Alex B.; McKenzie, Len J.; Pitcher, C. Roland; Coles, Robert G.

    2008-09-01

    The distribution and nutritional profiles of sub-tidal seagrasses from the Torres Strait were surveyed and mapped across an area of 31,000 km 2. Benthic sediment composition, water depth, seagrass species type and nutrients were sampled at 168 points selected in a stratified representative pattern. Eleven species of seagrass were present at 56 (33.3%) of the sample points. Halophila spinulosa, Halophila ovalis, Cymodocea serrulata and Syringodium isoetifolium were the most common species and these were nutrient profiled. Sub-tidal seagrass distribution (and associated seagrass nutrient concentrations) was generally confined to northern-central and south-western regions of the survey area (Seagrass nitrogen and starch content, the most important nutrients for marine herbivores, were significantly correlated with species and with the plant component (above or below ground). For all seagrass species, the above-ground component (shoots and leaves) possessed greater nitrogen concentrations than the below-ground component (roots and rhizomes), which possessed greater starch concentrations. S. isoetifolium had the highest total nitrogen concentrations (1.40±0.05% DW). However, it also had higher fibre concentrations (38.2±0.68% DW) relative to the other four species. H. ovalis possessed the highest starch concentrations (2.76±0.12% DW) and highest digestibility (83.24±0.66% DW) as well as the lowest fibre (27.2±0.66% DW). The high relative abundance (found at 55% of the sites that had seagrass) and nutrient quality characteristics of H. ovalis make it an important source of energy to marine herbivores that forage sub-tidally in the Torres Strait. There were two regions in Torres Strait (north-central and south-western) where sub-tidal seagrass meadows were prevalent and of relatively higher

  3. Newborn infants perceive abstract numbers.

    PubMed

    Izard, Véronique; Sann, Coralie; Spelke, Elizabeth S; Streri, Arlette

    2009-06-23

    Although infants and animals respond to the approximate number of elements in visual, auditory, and tactile arrays, only human children and adults have been shown to possess abstract numerical representations that apply to entities of all kinds (e.g., 7 samurai, seas, or sins). Do abstract numerical concepts depend on language or culture, or do they form a part of humans' innate, core knowledge? Here we show that newborn infants spontaneously associate stationary, visual-spatial arrays of 4-18 objects with auditory sequences of events on the basis of number. Their performance provides evidence for abstract numerical representations at the start of postnatal experience.

  4. Responses of four Indo-West Pacific seagrass species to shading.

    PubMed

    Collier, Catherine J; Waycott, Michelle; Ospina, Ana Giraldo

    2012-01-01

    Seagrasses of the Great Barrier Reef predominantly occur in coastal regions where terrestrial inputs modify water quality and photosynthetic light is highly variable. Responses to shading were tested for Cymodocea serrulata, Halodule uninervis, Thalassia hemprichii and Zostera muelleri. In aquaria, four light treatments - high (66% surface light), moderate (31%), low (14%) and very low light (1%) treatments - were applied for 102d. Stress responses in the low and very low light treatments occurred in the following sequence: metabolic and physiological changes (reduced growth, increased pigment concentrations and photosynthetic efficiency); shedding (leaf loss, shoot loss) and production of new, altered tissue (leaves with reduced length, width and thickness). Complete shoot loss was projected after 76 (Z. muelleri) to 130d (T. hemprichii). Responses were slower in the low than in the very low treatment, therefore, efforts to minimize water quality degradation will be rewarded with delayed impacts to seagrasses.

  5. The detrimental consequences for seagrass of ineffective marine park management related to boat anchoring.

    PubMed

    La Manna, G; Donno, Y; Sarà, G; Ceccherelli, G

    2015-01-15

    Posidonia oceanica (L.) Delile meadows are recognized as priority habitat for conservation by the EU Habitats Directive. The La Maddalena Archipelago National Park (Mediterranean Sea) P. oceanica meadow, the dominant coastal habitat of the area, is mostly threatened by boat anchoring. 12 years after the establishment of mooring fields and anchoring restrictions, a study was conducted to measure their effectiveness on the conservation of seagrass and the mitigation of anchoring damage. We found that: (i) the condition of P. oceanica was disturbed, both in the mooring fields and in control locations; (ii) mooring fields and anchoring restrictions did not show to be an efficient system for the protection of seagrass, in fact anchor scars increased after the tourist season; (iii) the mooring systems had an impact on the surrounding area of the meadow, probably due to their misuse. On the basis of these results, management recommendations for marine parks are proposed.

  6. Effects of Copper Exposure on Photosynthesis and Growth of the Seagrass Cymodocea nodosa: An Experimental Assessment.

    PubMed

    Llagostera, Izaskun; Cervantes, Daniel; Sanmartí, Neus; Romero, Javier; Pérez, Marta

    2016-09-01

    Seagrasses form some of the most important coastal habitats. They may be negatively affected by trace metal contamination in certain coastal areas. In this study we experimentally assessed selected morphological and physiological traits of the seagrass Cymodocea nodosa, with increasing concentrations of copper (Cu) under controlled laboratory conditions. Short term (21 days) sub-lethal effects such as decreased maximum quantum yield, increased leaf necrosis and decreased shoot growth and shoot recruitment were clearly observed at the highest Cu exposure (5 mg L(-1)), while the effects were weaker at the intermediate concentration (2.5 mg L(-1)) and almost absent at the lowest concentration (1 mg L(-1)), indicating that this species is highly tolerant to copper exposure, at least in the short term. This fact could help to explain its distribution in relatively polluted coastal waters.

  7. Salinity fluctuation of the brine discharge affects growth and survival of the seagrass Cymodocea nodosa.

    PubMed

    Garrote-Moreno, A; Fernández-Torquemada, Y; Sánchez-Lizaso, J L

    2014-04-15

    The increase of seawater desalination plants may affect seagrasses as a result of its hypersaline effluents. There are some studies on the salinity tolerance of seagrasses under controlled laboratory conditions, but few have been done in situ. To this end, Cymodocea nodosa shoots were placed during one month at four localities: two close to a brine discharge; and the other two not affected by the discharge, and this experiment was repeated four times. The results obtained showed a decrease in growth and an increased mortality at the localities affected by the brine discharge. An increase was detected in the percentage of horizontal shoots in respect to vertical shoots at the impacted localities. It is probably that not only the average salinity, but also the constant salinity fluctuations and slightly higher temperatures associated with the brine that may have caused physiological stress thus reducing C. nodosa growth and survival.

  8. Resource utilization and trophic position of nematodes and harpacticoid copepods in and adjacent to Zostera noltii beds

    NASA Astrophysics Data System (ADS)

    Vafeiadou, A.-M.; Materatski, P.; Adão, H.; De Troch, M.; Moens, T.

    2014-07-01

    This study examines the resource use and trophic position of nematodes and harpacticoid copepods at the genus/species level in an estuarine food web in Zostera noltii beds and in adjacent bare sediments using the natural abundance of stable carbon and nitrogen isotopes. Microphytobenthos and/or epiphytes are among the main resources of most taxa, but seagrass detritus and sediment particulate organic matter contribute as well to meiobenthos nutrition, which are also available in deeper sediment layers and in unvegetated patches close to seagrass beds. A predominant dependence on chemoautotrophic bacteria was demonstrated for the nematode genus Terschellingia and the copepod family Cletodidae. A predatory feeding mode is illustrated for Paracomesoma and other Comesomatidae, which were previously considered first-level consumers (deposit feeders) according to their buccal morphology. The considerable variation found in both resource use and trophic level among nematode genera from the same feeding type, and even among congeneric nematode species, shows that the interpretation of nematode feeding ecology based purely on mouth morphology should be avoided.

  9. Population structure and genetic diversity among eelgrass (Zostera marina) beds and depths in San Francisco Bay.

    PubMed

    Ort, Brian S; Cohen, C Sarah; Boyer, Katharyn E; Wyllie-Echeverria, Sandy

    2012-07-01

    The seagrass Zostera marina is widely distributed in coastal regions throughout much of the northern hemisphere, forms the foundation of an important ecological habitat, and is suffering population declines. Studies in the Atlantic and Pacific oceans indicate that the degree of population genetic differentiation is location dependent. San Francisco Bay, California, USA, is a high-current, high-wind environment where rafting of seed-bearing shoots has the potential to enhance genetic connectivity among Z. marina populations. We tested Z. marina from six locations, including one annual population, within the bay to assess population differentiation and to compare levels of within-population genetic diversity. Using 7 microsatellite loci, we found significant differentiation among all populations. The annual population had significantly higher clonal diversity than the others but showed no detectible differences in heterozygosity or allelic richness. There appears to be sufficient input of genetic variation through sexual reproduction or immigration into the perennial populations to prevent significant declines in the number and frequency of alleles. In additional depth comparisons, we found differentiation among deep and shallow portions in 1 of 3 beds evaluated. Genetic drift, sweepstakes recruitment, dispersal limitation, and possibly natural selection may have combined to produce genetic differentiation over a spatial scale of 3-30 km in Z. marina. This implies that the scale of genetic differentiation may be smaller than expected for seagrasses in other locations too. We suggest that populations in close proximity may not be interchangeable for use as restoration material.

  10. Treatment bed microbiological control

    NASA Technical Reports Server (NTRS)

    Janauer, Gilbert E.; Fitzpatrick, Timothy W.; Kril, Michael B.; Wilber, Georgia A.; Sauer, Richard L.

    1987-01-01

    The effects of microbial fouling on treatment bed (TB) performance are being studied. Fouling of activated carbon (AC) and ion exchange resins (IEX) by live and devitalized bacteria can cause decreased capacity for selected sorbates with AC and IEX TB. More data are needed on organic species removal in the trace region of solute sorption isotherms. TB colonization was prevented by nonclassical chemical disinfectant compositions (quaternary ammonium resins) applied in suitable configurations. Recently, the protection of carbon beds via direct disinfectant impregnation has shown promise. Effects (of impregnation) upon bed sorption/removal characteristics are to be studied with representative contaminants. The potential need to remove solutes added or produced during water disinfection and/or TB microbiological control must be investigated.

  11. Reconstruction of large area defect of the nail bed by cross finger fascial flap combined with split-thickness toe nail bed graft

    PubMed Central

    Yang, Jianyun; Wang, Tao; Yu, Cong; Gu, Yudong; Jia, Xiaotian

    2017-01-01

    Abstract Fingertip injury commonly results in avulsion of the nail bed. For large area defects of the nail bed with distal phalanx exposure, methods for reconstruction of soft tissue defects are scarcely mentioned in the literature. From May 2014 to January 2016, 6 patients with large area defects of the nail bed with distal phalanx exposure were enrolled. A new surgical method, cross finger fascial flap combined with thin split-thickness toe nail bed graft, was applied in all patients. All the 6 patients were followed-up at least 3 months. Good blood supply and no infections were observed. The lengths of the thumb or fingers were preserved. Acceptable appearance and nail bed growth were noted. The donor sites showed no dysfunction or deformity. Cross finger fascial flap combined with thin split-thickness toe nail bed graft is a new and rewarding surgical method to reconstruct large area defect of the nail bed with distal phalanx exposure. PMID:28178151

  12. Seagrass Proliferation Precedes Mortality during Hypo-Salinity Events: A Stress-Induced Morphometric Response

    PubMed Central

    Collier, Catherine J.; Villacorta-Rath, Cecilia; van Dijk, Kor-jent; Takahashi, Miwa; Waycott, Michelle

    2014-01-01

    Halophytes, such as seagrasses, predominantly form habitats in coastal and estuarine areas. These habitats can be seasonally exposed to hypo-salinity events during watershed runoff exposing them to dramatic salinity shifts and osmotic shock. The manifestation of this osmotic shock on seagrass morphology and phenology was tested in three Indo-Pacific seagrass species, Halophila ovalis, Halodule uninervis and Zostera muelleri, to hypo-salinity ranging from 3 to 36 PSU at 3 PSU increments for 10 weeks. All three species had broad salinity tolerance but demonstrated a moderate hypo-salinity stress response – analogous to a stress induced morphometric response (SIMR). Shoot proliferation occurred at salinities <30 PSU, with the largest increases, up to 400% increase in shoot density, occurring at the sub-lethal salinities <15 PSU, with the specific salinity associated with peak shoot density being variable among species. Resources were not diverted away from leaf growth or shoot development to support the new shoot production. However, at sub-lethal salinities where shoots proliferated, flowering was severely reduced for H. ovalis, the only species to flower during this experiment, demonstrating a diversion of resources away from sexual reproduction to support the investment in new shoots. This SIMR response preceded mortality, which occurred at 3 PSU for H. ovalis and 6 PSU for H. uninervis, while complete mortality was not reached for Z. muelleri. This is the first study to identify a SIMR in seagrasses, being detectable due to the fine resolution of salinity treatments tested. The detection of SIMR demonstrates the need for caution in interpreting in-situ changes in shoot density as shoot proliferation could be interpreted as a healthy or positive plant response to environmental conditions, when in fact it could signal pre-mortality stress. PMID:24705377

  13. Extreme temperatures, foundation species, and abrupt ecosystem change: an example from an iconic seagrass ecosystem.

    PubMed

    Thomson, Jordan A; Burkholder, Derek A; Heithaus, Michael R; Fourqurean, James W; Fraser, Matthew W; Statton, John; Kendrick, Gary A

    2015-04-01

    Extreme climatic events can trigger abrupt and often lasting change in ecosystems via the reduction or elimination of foundation (i.e., habitat-forming) species. However, while the frequency/intensity of extreme events is predicted to increase under climate change, the impact of these events on many foundation species and the ecosystems they support remains poorly understood. Here, we use the iconic seagrass meadows of Shark Bay, Western Australia--a relatively pristine subtropical embayment whose dominant, canopy-forming seagrass, Amphibolis antarctica, is a temperate species growing near its low-latitude range limit--as a model system to investigate the impacts of extreme temperatures on ecosystems supported by thermally sensitive foundation species in a changing climate. Following an unprecedented marine heat wave in late summer 2010/11, A. antarctica experienced catastrophic (>90%) dieback in several regions of Shark Bay. Animal-borne video footage taken from the perspective of resident, seagrass-associated megafauna (sea turtles) revealed severe habitat degradation after the event compared with a decade earlier. This reduction in habitat quality corresponded with a decline in the health status of largely herbivorous green turtles (Chelonia mydas) in the 2 years following the heat wave, providing evidence of long-term, community-level impacts of the event. Based on these findings, and similar examples from diverse ecosystems, we argue that a generalized framework for assessing the vulnerability of ecosystems to abrupt change associated with the loss of foundation species is needed to accurately predict ecosystem trajectories in a changing climate. This includes seagrass meadows, which have received relatively little attention in this context. Novel research and monitoring methods, such as the analysis of habitat and environmental data from animal-borne video and data-logging systems, can make an important contribution to this framework.

  14. Influence of Sedimentary and Seagrass Microbial Communities on Shallow-Water Benthic Optical Properties

    DTIC Science & Technology

    2008-09-30

    Similarly, determine the biomass, composition, and temporal variation of microorganisms epiphytic on seagrass blades at Lee Stocking Island (turtle...following section. 1) In October, we will submit a manuscript, authored by Drake, Dobbs, and Zimmerman, and entitled “Effects of epiphyte load on... epiphytes collected from LSI and Monterey Bay. There are two types of lipid analyses we have performed. The first yields a microbial biomass value

  15. An Annotated Bibliography of Seagrasses with Emphasis on Planting and Propagation Techniques.

    DTIC Science & Technology

    1980-09-01

    of the total algal flora . Two groups of epi- phytes are recognized, the year-round species and the seasonal annuals. Among the year-round species are...research, especially in Veracruz , Mexico. Also included is an assessment of the effects of human activity on seagrass ecosystems, and suggestions of...approximately 11 species of submerged aquatic vegetation dominant in the waters of the Chesapeake Bay. Submerged aquatic flora con- stitutes the principal source

  16. Seagrass sediments reveal the long-term deterioration of an estuarine ecosystem.

    PubMed

    Serrano, Oscar; Lavery, Paul; Masque, Pere; Inostroza, Karina; Bongiovanni, James; Duarte, Carlos

    2016-04-01

    The study of a Posidonia australis sediment archive has provided a record of ecosystem dynamics and processes over the last 600 years in Oyster Harbour (SW Australia). Ecosystem shifts are a widespread phenomenon in coastal areas, and this study identifies baseline conditions and the time-course of ecological change (cycles, trends, resilience and thresholds of ecosystem change) under environmental stress in seagrass-dominated ecosystem. The shifts in the concentrations of chemical elements, carbonates, sediments <0.125 mm and stable carbon isotope signatures (δ(13) C) of the organic matter were detected between 1850s and 1920s, whereas the shift detected in P concentration occurred several decades later (1960s). The first degradation phase (1850s-1950s) follows the onset of European settlement in Australia and was characterized by a strong increase in sediment accumulation rates and fine-grained particles, driven primarily by enhanced run-off due to land clearance and agriculture in the catchment. About 80% of total seagrass area at Oyster Harbour was lost during the second phase of environmental degradation (1960s until present). The sharp increase in P concentration and the increasing contribution of algae and terrestrial inputs into the sedimentary organic matter pool around 1960s provides compelling evidence of the documented eutrophication of the estuary and the subsequent loss of seagrass meadows. The results presented demonstrate the power of seagrass sedimentary archives to reconstruct the trajectories of anthropogenic pressures on estuarine ecosystem and the associated regime shifts, which can be used to improve the capacity of scientists and environmental managers to understand, predict and better manage ecological change in these ecosystems.

  17. Deficiencies in structured medical abstracts.

    PubMed

    Froom, P; Froom, J

    1993-07-01

    This study was carried out to determine if the content of structured abstracts conforms with recommendations of the Ad Hoc Working Group for the critical appraisal of the medical literature as adopted by the Annals of Internal Medicine. The study design was a survey. All articles published in Annals of Internal Medicine in 1991, excluding editorials, case-reports, literature reviews, decision analysis, studies in medical education, descriptive studies of clinical and basic phenomena, and papers lacking a structured abstract, were studied. Of a total of 150 articles, 20 were excluded. The abstract and text of each article were assessed for the presence of the following items; patient selection criteria, statements concerning extrapolation of findings, need for further study, and whether or not the information should be used now. Number of refusers, drop outs and reason(s) for drop outs were assessed for intervention and prospective cohort studies only. Deficiencies of assessed items were noted in both abstracts and texts. For abstracts, patient selection criteria, numbers of refusers, number of drop outs and reason(s) for drop outs were reported in 44.6% (58/130), 3.1% (4/130), 16.9% (14/83) and 2.4% (2/83) respectively. These items were reported more frequently in the texts 87.7% (114/130), 9.2% (12/130), 60.2% (50/83) and 37.3% (31/83) respectively (p < 0.05). Statements concerning extrapolation of findings, need for further study and use of information now were also more frequent in texts than abstracts (p < 0.0001). A large number of structured abstracts published in the Annals of Internal Medicine in 1991, lack information recommended by the Ad Hoc Working Group. Our findings should not be extrapolated to other journals requiring structured abstracts.

  18. Fluidized bed coal desulfurization

    NASA Technical Reports Server (NTRS)

    Ravindram, M.

    1983-01-01

    Laboratory scale experiments were conducted on two high volatile bituminous coals in a bench scale batch fluidized bed reactor. Chemical pretreatment and posttreatment of coals were tried as a means of enhancing desulfurization. Sequential chlorination and dechlorination cum hydrodesulfurization under modest conditions relative to the water slurry process were found to result in substantial sulfur reductions of about 80%. Sulfur forms as well as proximate and ultimate analyses of the processed coals are included. These studies indicate that a fluidized bed reactor process has considerable potential for being developed into a simple and economic process for coal desulfurization.

  19. Staged fluidized bed

    DOEpatents

    Mallon, R.G.

    1983-05-13

    The invention relates to oil shale retorting and more particularly to staged fluidized bed oil shale retorting. Method and apparatus are disclosed for narrowing the distribution of residence times of any size particle and equalizing the residence times of large and small particles in fluidized beds. Particles are moved up one fluidized column and down a second fluidized column with the relative heights selected to equalize residence times of large and small particles. Additional pairs of columns are staged to narrow the distribution of residence times and provide complete processing of the material.

  20. Interactions between Seagrass Complexity, Hydrodynamic Flow and Biomixing Alter Food Availability for Associated Filter-Feeding Organisms

    PubMed Central

    González-Ortiz, Vanessa; Egea, Luis G.; Jiménez-Ramos, Rocio; Moreno-Marín, Francisco; Pérez-Lloréns, José L.; Bouma, Tjeed J.; Brun, Fernando G.

    2014-01-01

    Seagrass shoots interact with hydrodynamic forces and thereby a positively or negatively influence the survival of associated species. The modification of these forces indirectly alters the physical transport and flux of edible particles within seagrass meadows, which will influence the growth and survivorship of associated filter-feeding organisms. The present work contributes to gaining insight into the mechanisms controlling the availability of resources for filter feeders inhabiting seagrass canopies, both from physical (influenced by seagrass density and patchiness) and biological (regulated by filter feeder density) perspectives. A factorial experiment was conducted in a large racetrack flume, which combined changes in hydrodynamic conditions, chlorophyll a concentration in the water and food intake rate (FIR) in a model active filter-feeding organism (the cockle). Results showed that seagrass density and patchiness modified both hydrodynamic forces and availability of resources for filter feeders. Chlorophyll a water content decreased to 50% of the initial value when densities of both seagrass shoots and cockles were high. Also, filter feeder density controlled resource availability within seagrass patches, depending on its spatial position within the racetrack flume. Under high density of filter-feeding organisms, chlorophyll a levels were lower between patches. This suggests that the pumping activity of cockles (i.e. biomixing) is an emergent key factor affecting both resource availability and FIR for filter feeders in dense canopies. Applying our results to natural conditions, we suggest the existence of a direct correlation between habitat complexity (i.e. shoot density and degree of patchiness) and filter feeders density. Fragmented and low-density patches seem to offer both greater protection from hydrodynamic forces and higher resource availability. In denser patches, however, resources are allocated mostly within the canopy, which would benefit

  1. Interactions between seagrass complexity, hydrodynamic flow and biomixing alter food availability for associated filter-feeding organisms.

    PubMed

    González-Ortiz, Vanessa; Egea, Luis G; Jiménez-Ramos, Rocio; Moreno-Marín, Francisco; Pérez-Lloréns, José L; Bouma, Tjeed J; Brun, Fernando G

    2014-01-01

    Seagrass shoots interact with hydrodynamic forces and thereby a positively or negatively influence the survival of associated species. The modification of these forces indirectly alters the physical transport and flux of edible particles within seagrass meadows, which will influence the growth and survivorship of associated filter-feeding organisms. The present work contributes to gaining insight into the mechanisms controlling the availability of resources for filter feeders inhabiting seagrass canopies, both from physical (influenced by seagrass density and patchiness) and biological (regulated by filter feeder density) perspectives. A factorial experiment was conducted in a large racetrack flume, which combined changes in hydrodynamic conditions, chlorophyll a concentration in the water and food intake rate (FIR) in a model active filter-feeding organism (the cockle). Results showed that seagrass density and patchiness modified both hydrodynamic forces and availability of resources for filter feeders. Chlorophyll a water content decreased to 50% of the initial value when densities of both seagrass shoots and cockles were high. Also, filter feeder density controlled resource availability within seagrass patches, depending on its spatial position within the racetrack flume. Under high density of filter-feeding organisms, chlorophyll a levels were lower between patches. This suggests that the pumping activity of cockles (i.e. biomixing) is an emergent key factor affecting both resource availability and FIR for filter feeders in dense canopies. Applying our results to natural conditions, we suggest the existence of a direct correlation between habitat complexity (i.e. shoot density and degree of patchiness) and filter feeders density. Fragmented and low-density patches seem to offer both greater protection from hydrodynamic forces and higher resource availability. In denser patches, however, resources are allocated mostly within the canopy, which would benefit

  2. 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

  3. Use of carbon monoxide and hydrogen by a bacteria-animal symbiosis from seagrass sediments.

    PubMed

    Kleiner, Manuel; Wentrup, Cecilia; Holler, Thomas; Lavik, Gaute; Harder, Jens; Lott, Christian; Littmann, Sten; Kuypers, Marcel M M; Dubilier, Nicole

    2015-12-01

    The gutless marine worm Olavius algarvensis lives in symbiosis with chemosynthetic bacteria that provide nutrition by fixing carbon dioxide (CO2 ) into biomass using reduced sulfur compounds as energy sources. A recent metaproteomic analysis of the O. algarvensis symbiosis indicated that carbon monoxide (CO) and hydrogen (H2 ) might also be used as energy sources. We provide direct evidence that the O. algarvensis symbiosis consumes CO and H2 . Single cell imaging using nanoscale secondary ion mass spectrometry revealed that one of the symbionts, the γ3-symbiont, uses the energy from CO oxidation to fix CO2 . Pore water analysis revealed considerable in-situ concentrations of CO and H2 in the O. algarvensis environment, Mediterranean seagrass sediments. Pore water H2 concentrations (89-2147 nM) were up to two orders of magnitude higher than in seawater, and up to 36-fold higher than previously known from shallow-water marine sediments. Pore water CO concentrations (17-51 nM) were twice as high as in the overlying seawater (no literature data from other shallow-water sediments are available for comparison). Ex-situ incubation experiments showed that dead seagrass rhizomes produced large amounts of CO. CO production from decaying plant material could thus be a significant energy source for microbial primary production in seagrass sediments.

  4. Seagrasses, Dredging and Light in Laguna Madre, Texas, U.S.A.

    NASA Astrophysics Data System (ADS)

    Onuf, Christopher P.

    1994-07-01

    Light reduction resulting from maintenance dredging was the suspected cause of large-scale loss of seagrass cover in deep parts of Laguna Madre between surveys conducted in 1965 and 1974. Additional changes to 1988, together with an analysis of dredging frequency and intensity for different parts of the laguna, were consistent with this interpretation. Intensive monitoring of the underwater light regime and compilation of detailed environmental data for 3 months before and 15 months after a dredging project in 1988 revealed reduced light attributable to dredging in four of eight subdivisions of the study area, including the most extensive seagrass meadow in the study area. Dredging effects were strongest close to disposal areas used during this project but still were detectable on transects >1·2 km from the nearest dredge disposal area. In the subdivision of the study area where most of the dredge disposal occurred, light attenuation was increased throughout the 15 months of observation after dredging. In the seagrass meadow and the transition zone at the outer edge of the meadow, effects were evident up to 10 months after dredging. Resuspension and dispersion events caused by wind-generated waves are responsible for the propagation of dredge-related turbidity over space and time in this system.

  5. Watershed discharge patterns, secondary consumer abundances, and seagrass habitat condition in Yap, Micronesia.

    PubMed

    Houk, Peter; Golbuu, Yimnang; Gorong, Berna; Gorong, Thomas; Fillmed, Christina

    2013-06-15

    Watershed discharge, water quality, and seagrass assemblages were examined along the western coast of Yap Proper, Micronesia. Submarine groundwater discharge (SGD) during low tides associated with new and full moons contributed disproportionally to freshwater delivery where compromised Thalassia habitats existed. Despite SGD influence, nutrient sampling indicated that one characteristic regime may be a net import of new nitrogen and phosphorous (NO3 and PO4) from offshore to inshore waters, agreeing with sparse watershed development. Biologically recycled nitrogen (NH4), however, was highest where SGD contribution was largest. Time-and-tide-limited sampling likely precluded generalized relationships between SGD and NH4 across the entire study area, however, spatial profiling of SGD during low-tide events (i.e., a proxy to nutrient input) was strongly associated with seagrass habitat condition (defined within). Concomitantly, sea cucumber densities were over a magnitude of order lower than in regionally comparable Thalassia habitats, and negatively correlated with seagrass condition. Both top-down and bottom-up considerations are discussed.

  6. Burial Duration and Frequency Influences Resilience of Differing Propagule Types in a Subtidal Seagrass, Posidonia australis.

    PubMed

    Campbell, Marnie L

    2016-01-01

    Sedimentation that leads to periodic, and often prolonged, burial events is becoming more common on the world's coastlines as human populations expand and create urbanised marine environments. Different seagrass species react differently to sediment burial but many species in the southern hemisphere are yet to be examined. How seagrasses react to burial has restoration implications. There is a need to critically assess seagrass transplant propagule responses to periodic (pulse) and prolonged (press) burial events before selecting the most appropriate species, transplant propagule, and transplant site. In my study, mesocosm experiments, coupled with field measurements were used to assess how sexual (seedlings) and vegetative (sprigs) propagules of Posidonia australis responded to pulse and press burial events. Seedlings were highly susceptible to burial (both pulse and press), with no survival at the end of the experimental period. In contrast, rhizome growth in vegetative propagules was stimulated by pulse burial, although press burial events resulted in mortality. The implication for Posidonia australis restoration efforts in areas where burial is periodic, was that vegetative propagules are optimal transplant units, in comparison to seedlings. Press burial however, renders a transplant site sub-optimal for both seedling and sprig transplants.

  7. Use of carbon monoxide and hydrogen by a bacteria-animal symbiosis from seagrass sediments

    DOE PAGES

    Kleiner, Manuel; Wentrup, Cecilia; Holler, Thomas; ...

    2015-05-27

    The gutless marine worm Olavius algarvensis lives in symbiosis with chemosynthetic bacteria that provide nutrition by fixing carbon dioxide (CO2) into biomass using reduced sulfur compounds as energy sources. A recent metaproteomic analysis of the O. algarvensis symbiosis indicated that carbon monoxide (CO) and hydrogen (H2) might also be used as energy sources. We provide direct evidence that the O. algarvensis symbiosis consumes CO and H2. Single cell imaging using nanoscale secondary ion mass spectrometry revealed that one of the symbionts, the γ3-symbiont, uses the energy from CO oxidation to fix CO2. Pore water analysis revealed considerable in-situ concentrations ofmore » CO and H2 in the O. algarvensis environment, Mediterranean seagrass sediments. Pore water H2 concentrations (89-2147 nM) were up to two orders of magnitude higher than in seawater, and up to 36-fold higher than previously known from shallow-water marine sediments. Pore water CO concentrations (17-51 nM) were twice as high as in the overlying seawater (no literature data from other shallow-water sediments are available for comparison). Ex-situ incubation experiments showed that dead seagrass rhizomes produced large amounts of CO. Lastly, CO production from decaying plant material could thus be a significant energy source for microbial primary production in seagrass sediments.« less

  8. Use of carbon monoxide and hydrogen by a bacteria–animal symbiosis from seagrass sediments

    PubMed Central

    Holler, Thomas; Lavik, Gaute; Harder, Jens; Lott, Christian; Littmann, Sten; Kuypers, Marcel M. M.; Dubilier, Nicole

    2015-01-01

    Summary The gutless marine worm O lavius algarvensis lives in symbiosis with chemosynthetic bacteria that provide nutrition by fixing carbon dioxide (CO 2) into biomass using reduced sulfur compounds as energy sources. A recent metaproteomic analysis of the O . algarvensis symbiosis indicated that carbon monoxide (CO) and hydrogen (H 2) might also be used as energy sources. We provide direct evidence that the O . algarvensis symbiosis consumes CO and H 2. Single cell imaging using nanoscale secondary ion mass spectrometry revealed that one of the symbionts, the γ3‐symbiont, uses the energy from CO oxidation to fix CO 2. Pore water analysis revealed considerable in‐situ concentrations of CO and H 2 in the O . algarvensis environment, Mediterranean seagrass sediments. Pore water H 2 concentrations (89–2147 nM) were up to two orders of magnitude higher than in seawater, and up to 36‐fold higher than previously known from shallow‐water marine sediments. Pore water CO concentrations (17–51 nM) were twice as high as in the overlying seawater (no literature data from other shallow‐water sediments are available for comparison). Ex‐situ incubation experiments showed that dead seagrass rhizomes produced large amounts of CO. CO production from decaying plant material could thus be a significant energy source for microbial primary production in seagrass sediments. PMID:26013766

  9. Gradients in the Number of Species at Reef-Seagrass Ecotones Explained by Gradients in Abundance

    PubMed Central

    Tuya, Fernando; Vanderklift, Mathew A.; Wernberg, Thomas; Thomsen, Mads S.

    2011-01-01

    Gradients in the composition and diversity (e.g. number of species) of faunal assemblages are common at ecotones between juxtaposed habitats. Patterns in the number of species, however, can be confounded by patterns in abundance of individuals, because more species tend to be found wherever there are more individuals. We tested whether proximity to reefs influenced patterns in the composition and diversity (‘species density’ = number of species per area and ‘species richness’ = number of species per number of individuals) of prosobranch gastropods in meadows of two seagrasses with different physiognomy: Posidonia and Amphibolis. A change in the species composition was observed from reef-seagrass edges towards the interiors of Amphibolis, but not in Posidonia meadows. Similarly, the abundance of gastropods and species density was higher at edges relative to interiors of Amphibolis meadows, but not in Posidonia meadows. However, species richness was not affected by proximity to reefs in either type of seagrass meadow. The higher number of species at the reef-Amphibolis edge was therefore a consequence of higher abundance, rather than species richness per se. These results suggest that patterns in the composition and diversity of fauna with proximity to adjacent habitats, and the underlying processes that they reflect, likely depend on the physiognomy of the habitat. PMID:21629654

  10. Gradients in the number of species at reef-seagrass ecotones explained by gradients in abundance.

    PubMed

    Tuya, Fernando; Vanderklift, Mathew A; Wernberg, Thomas; Thomsen, Mads S

    2011-01-01

    Gradients in the composition and diversity (e.g. number of species) of faunal assemblages are common at ecotones between juxtaposed habitats. Patterns in the number of species, however, can be confounded by patterns in abundance of individuals, because more species tend to be found wherever there are more individuals. We tested whether proximity to reefs influenced patterns in the composition and diversity ('species density'  =  number of species per area and 'species richness'  =  number of species per number of individuals) of prosobranch gastropods in meadows of two seagrasses with different physiognomy: Posidonia and Amphibolis. A change in the species composition was observed from reef-seagrass edges towards the interiors of Amphibolis, but not in Posidonia meadows. Similarly, the abundance of gastropods and species density was higher at edges relative to interiors of Amphibolis meadows, but not in Posidonia meadows. However, species richness was not affected by proximity to reefs in either type of seagrass meadow. The higher number of species at the reef-Amphibolis edge was therefore a consequence of higher abundance, rather than species richness per se. These results suggest that patterns in the composition and diversity of fauna with proximity to adjacent habitats, and the underlying processes that they reflect, likely depend on the physiognomy of the habitat.

  11. The effects of in situ shading on the growth of a seagrass, Syringodium isoetifolium

    NASA Astrophysics Data System (ADS)

    Fokeera-Wahedally, S. B. M.; Bhikajee, M.

    2005-08-01

    The effect of light reduction on a tropical seagrass, Syringodium isoetifolium, was examined over a period of six months (July 2001 to December 2001) in relation to leaf elongation rates, shoot densities and chlorophyll content of the leaf blades. The experiment was carried out at Poste Lafayette, Mauritius, in winter (July to September) and summer (October to December) in the same seagrass meadow. In both seasons three plots were shaded with Sarlon cloth (75% light cut-off), with three unshaded plots as controls. The growth rate for both winter and summer was higher in the shaded plots than in the control. Leaf elongation rates were higher in shaded plots in summer than in the shaded plots in winter. Blade chlorophyll was also higher in the shaded plots than in unshaded plots both in winter and in summer. There was no significant difference in the shoot density between plots. These results are consistent with the suggestion that high irradiance brings about a reduction in seagrass growth. The results also show that light is one of the factors that control the vertical growth response of S. isoetifolium as well as its photoreceptors.

  12. Model fit versus biological relevance: Evaluating photosynthesis-temperature models for three tropical seagrass species

    NASA Astrophysics Data System (ADS)

    Adams, Matthew P.; Collier, Catherine J.; Uthicke, Sven; Ow, Yan X.; Langlois, Lucas; O’Brien, Katherine R.

    2017-01-01

    When several models can describe a biological process, the equation that best fits the data is typically considered the best. However, models are most useful when they also possess biologically-meaningful parameters. In particular, model parameters should be stable, physically interpretable, and transferable to other contexts, e.g. for direct indication of system state, or usage in other model types. As an example of implementing these recommended requirements for model parameters, we evaluated twelve published empirical models for temperature-dependent tropical seagrass photosynthesis, based on two criteria: (1) goodness of fit, and (2) how easily biologically-meaningful parameters can be obtained. All models were formulated in terms of parameters characterising the thermal optimum (Topt) for maximum photosynthetic rate (Pmax). These parameters indicate the upper thermal limits of seagrass photosynthetic capacity, and hence can be used to assess the vulnerability of seagrass to temperature change. Our study exemplifies an approach to model selection which optimises the usefulness of empirical models for both modellers and ecologists alike.

  13. Determining the trophic guilds of fishes and macroinvertebrates in a seagrass food web

    USGS Publications Warehouse

    Luczkovich, J.J.; Ward, G.P.; Johnson, J.C.; Christian, R.R.; Baird, D.; Neckles, H.; Rizzo, W.M.

    2002-01-01

    We established trophic guilds of macroinvertebrate and fish taxa using correspondence analysis and a hierarchical clustering strategy for a seagrass food web in winter in the northeastern Gulf of Mexico. To create the diet matrix, we characterized the trophic linkages of macroinvertebrate and fish taxa. present in Hatodule wrightii seagrass habitat areas within the St. Marks National Wildlife Refuge (Florida) using binary data, combining dietary links obtained from relevant literature for macroinvertebrates with stomach analysis of common fishes collected during January and February of 1994. Heirarchical average-linkage cluster analysis of the 73 taxa of fishes and macroinvertebrates in the diet matrix yielded 14 clusters with diet similarity greater than or equal to 0.60. We then used correspondence analysis with three factors to jointly plot the coordinates of the consumers (identified by cluster membership) and of the 33 food sources. Correspondence analysis served as a visualization tool for assigning each taxon to one of eight trophic guilds: herbivores, detritivores, suspension feeders, omnivores, molluscivores, meiobenthos consumers, macrobenthos consumers, and piscivores. These trophic groups, cross-classified with major taxonomic groups, were further used to develop consumer compartments in a network analysis model of carbon flow in this seagrass ecosystem. The method presented here should greatly improve the development of future network models of food webs by providing an objective procedure for aggregating trophic groups.

  14. Determining the trophic guilds of fishes and macroinvertebrates in a seagrass food web

    USGS Publications Warehouse

    Luczkovich, J.J.; Ward, G.P.; Johnson, J.C.; Christian, R.R.; Baird, D.; Neckles, H.; Rizzo, W.M.

    2002-01-01

    We established trophic guilds of macroinvertebrate and fish taxa using correspondence analysis and a hierarchical clustering strategy for a seagrass food web in winter in the northeastern Gulf of Mexico. To create the diet matrix, we characterized the trophic linkages of macroinvertebrate and fish taxa present in Halodule wrightii seagrass habitat areas within the St. Marks National Wildlife Refuge (Florida) using binary data, combining dietary links obtained from relevant literature for macroinvertebrates with stomach analysis of common fishes collected during January and February of 1994. Heirarchical average-linkage cluster analysis of the 73 taxa of fishes and macroinvertebrates in the diet matrix yielded 14 clusters with diet similarity ??? 0.60. We then used correspondence analysis with three factors to jointly plot the coordinates of the consumers (identified by cluster membership) and of the 33 food sources. Correspondence analysis served as a visualization tool for assigning each taxon to one of eight trophic guilds: herbivores, detritivores, suspension feeders, omnivores, molluscivores, meiobenthos consumers, macrobenthos consumers, and piscivores. These trophic groups, cross-classified with major taxonomic groups, were further used to develop consumer compartments in a network analysis model of carbon flow in this seagrass ecosystem. The method presented here should greatly improve the development of future network models of food webs by providing an objective procedure for aggregating trophic groups.

  15. Effects of intertidal seagrass habitat fragmentation on turbulent diffusion and retention time of solutes.

    PubMed

    Lara, M; Peralta, G; Alonso, J J; Morris, E P; González-Ortiz, V; Rueda-Márquez, J J; Pérez-Lloréns, J L

    2012-11-01

    An in-depth knowledge of solutes advection and turbulent diffusion is crucial to estimate dispersion area and retention time (t(R)) of pollutants within seagrass habitats. However, there is little knowledge on the influence of seagrass habitat fragmentation on such mechanisms. A set of dye tracer experiments and acoustic Doppler velocimeter measurements (ADV) were conducted. Solute transport conditions were compared in between fragmented (FM) vs homogeneous (HM) intertidal meadows, and in vertical gradients (canopy vs overlaying flow). Results showed the highest horizontal diffusion coefficient (K(y), c.a. 10(-3)m(2)s(-1)) on FM and at the canopy-water column interface, whereas t(R) (2.6-5.6 min) was not affected by fragmentation. It suggests that (1) FM are more vulnerable to pollution events in terms of dispersion area and (2) at low tide, advection rather than turbulent diffusion determines t(R). Furthermore, Taylor's theorem is revealed as a powerful tool to analyze vertical gradients on K(y) within seagrass canopies.

  16. Burial Duration and Frequency Influences Resilience of Differing Propagule Types in a Subtidal Seagrass, Posidonia australis

    PubMed Central

    2016-01-01

    Sedimentation that leads to periodic, and often prolonged, burial events is becoming more common on the world’s coastlines as human populations expand and create urbanised marine environments. Different seagrass species react differently to sediment burial but many species in the southern hemisphere are yet to be examined. How seagrasses react to burial has restoration implications. There is a need to critically assess seagrass transplant propagule responses to periodic (pulse) and prolonged (press) burial events before selecting the most appropriate species, transplant propagule, and transplant site. In my study, mesocosm experiments, coupled with field measurements were used to assess how sexual (seedlings) and vegetative (sprigs) propagules of Posidonia australis responded to pul