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Sample records for benthic nepheloid layer

  1. Benthic nepheloid layers in the Gulf of Maine and Alexandrium cyst inventories

    PubMed Central

    Pilskaln, C.H.; Hayashi, K.; Keafer, B.A.; Anderson, D.M.; McGillicuddy, D.J.

    2014-01-01

    Cysts residing in benthic nepheloid layers (BNLs) documented in the Gulf of Maine have been proposed as a possible source of inoculum for annual blooms of a toxic dinoflagellate in the region. Herein we present a spatially extensive data set of the distribution and thickness of benthic nepheloid layers in the Gulf of Maine and the abundance and inventories of suspended Alexandrium fundyense cysts within these near-bottom layers. BNLs are pervasive throughout the gulf and adjacent Bay of Fundy with maximum layer thicknesses of 50–60 m observed. Mean BNL thickness is 30 m in the eastern gulf and Bay of Fundy, and 20 m in the western gulf. Cyst densities in the near-bottom particle resuspension layers varied by three orders of magnitude across the gulf with maxima of 105 cysts m−3. An important interconnection of elevated BNL cyst densities is observed between the Bay of Fundy, the Maine Coastal Current and the south-central region of the gulf. BNL cyst inventories estimated for the eastern and western gulf are each on the order of 1015 cysts, whereas the BNL inventory in the Bay of Fundy is on the order of 1016 . Although BNL cyst inventories in the eastern and western gulf are 1–2 orders of magnitude smaller than the abundance of cysts in the upper 1 cm of sediment in those regions, BNL and sediment-bound cyst inventories are comparable in the Bay of Fundy. The existence of widespread BNLs containing substantial cyst inventories indicates that these near-bottom layers represent an important source of germinating A. fundyense cysts in the region. PMID:25419055

  2. Benthic nepheloid layers in the Gulf of Maine and Alexandrium cyst inventories

    NASA Astrophysics Data System (ADS)

    Pilskaln, C. H.; Hayashi, K.; Keafer, B. A.; Anderson, D. M.; McGillicuddy, D. J.

    2014-05-01

    Cysts residing in benthic nepheloid layers (BNLs) documented in the Gulf of Maine have been proposed as a possible source of inoculum for annual blooms of a toxic dinoflagellate in the region. Herein we present a spatially extensive data set of the distribution and thickness of benthic nepheloid layers in the Gulf of Maine and the abundance and inventories of suspended Alexandrium fundyense cysts within these near-bottom layers. BNLs are pervasive throughout the gulf and adjacent Bay of Fundy with maximum layer thicknesses of 50-60 m observed. Mean BNL thickness is 30 m in the eastern gulf and Bay of Fundy, and 20 m in the western gulf. Cyst densities in the near-bottom particle resuspension layers varied by three orders of magnitude across the gulf with maxima of 105 cysts m-3. An important interconnection of elevated BNL cyst densities is observed between the Bay of Fundy, the Maine Coastal Current and the south-central region of the gulf. BNL cyst inventories estimated for the eastern and western gulf are each on the order of 1015 cysts, whereas the BNL inventory in the Bay of Fundy is on the order of 1016. Although BNL cyst inventories in the eastern and western gulf are 1-2 orders of magnitude smaller than the abundance of cysts in the upper 1 cm of sediment in those regions, BNL and sediment-bound cyst inventories are comparable in the Bay of Fundy. The existence of widespread BNLs containing substantial cyst inventories indicates that these near-bottom layers represent an important source of germinating A. fundyense cysts in the region.

  3. Sedimentary sources of old high molecular weight dissolved organic carbon from the ocean margin benthic nepheloid layer

    SciTech Connect

    Guo, L. Santschi, P.H.

    2000-02-01

    Average {sup 14}C ages of dissolved organic carbon (DOC) in the ocean are 3--6,000 years, and are influenced by old DOC from continental margins. However, sources of DOC from terrestrial, autochthonous, and sedimentary organic carbon seem to be too young to be responsible for the old DOC observed in the ocean. Since colloidal organic carbon (COC, i.e., high molecular weight DOC), which is chemically very similar to that of bulk DOC, can be effectively isolated from seawater using cross-flow ultrafiltration, it can hold clues to sources and pathways of DOC turnover in the ocean. Radiocarbon measurements on COC in the water column and benthic nepheloid layer (BNL) from two continental margin areas (the Middle Atlantic Bight and the Gulf of Mexico) and controlled laboratory experiments were carried out to study sources of old DOC in the ocean margin areas. Vertical distributions of suspended particulate matter (SPM), particulate organic carbon (POC), nitrogen (PON), and DOC in the water column and bottom waters near the sediment-water interface all demonstrate a well developed benthic nepheloid layer in both ocean margin areas. COC from the BNL was much older than COC from the overlying water column. These results, together with strong concentration gradients of SPM, POC, PON, and DOC, suggest a sedimentary source for organic carbon species and possibly for old COC as well in BNL waters. This is confirmed by the results from controlled laboratory experiments. The heterogeneity of {Delta}{sup 14}C signatures in bulk SOC thus points to a preferential release of old organic components from sediment resuspension, which can be the transport mechanism of the old benthic COC observed in ocean margin areas. Old COC from continental margin nepheloid layers may thus be a potential source of old DOC to the deep ocean.

  4. Aerobic methanotrophs drive the formation of a seasonal anoxic benthic nepheloid layer in monomictic Lake Lugano

    NASA Astrophysics Data System (ADS)

    Blees, Jan; Niemann, Helge; Wenk, Christine B.; Zopfi, Jacob; Schubert, Carsten J.; Jenzer, Joël S.; Veronesi, Mauro L.; Lehmann, Moritz F.

    2014-05-01

    In the southern basin of Lake Lugano, thermal stratification of the water column during summer and autumn leads to a lack of exchange between surface and deep water masses, and consequently to seasonal bottom water anoxia, associated with high methane concentrations. With the onset of bottom water anoxia, a dense layer of high particulate matter concentration - a so-called benthic nepheloid layer (BNL) - develops in the bottom waters. A sharp redox gradient marks the upper boundary of the BNL. At its maximum, the BNL extends 15 - 30 m from the sediment into the water column. We investigated the identity of the BNL and key environmental factors controlling its formation in the framework of a seasonal study. Compound specific C-isotope measurements and Fluorescence In Situ Hybridisation (FISH) of suspended particulate organic matter, radioactive tracer based measurements of methane oxidation, as well as investigation of geochemical water column parameters were performed in spring and autumn. Our analyses revealed that the microbial biomass within the BNL is dominated by methanotrophic bacteria. Aerobic methane oxidation (MOx) was restricted to a narrow zone at the top of the BNL, reaching maximum rates of up to 1.8 μM/day. The rates of MOx activity effectively consumed most (>99%) of the uprising methane, leading to the formation of a sharp CH4 concentration gradient and a strongly suppressed kinetic isotope effect (ɛ = -2.8o). CH4 oxidation was limited by the diffusive supply of O2 from the upper hypolimnion, implying that methanotrophy is the primary driver of the seasonal expansion of the anoxic bottom water volume, and explaining the vertical migration of the BNL in response to its own O2 consumption. The bulk organic matter extracted from the BNL was strongly depleted in 13C (δ13C < -60o), providing evidence for the incorporation of CH4-derived carbon into the biomass, suggesting that the BNL was composed of MOx-communities. This was further evidenced by four

  5. Mass-physical properties of surficial sediments on the Rhoˆne continental margin: implications for the nepheloid benthic layer

    NASA Astrophysics Data System (ADS)

    Chassefiere, Bernard

    1990-09-01

    Mass-physical properties of the surficial (upper 5 m) sediments on the Gulf of Lions continental margin were analysed, from more than 100 short (1 m) and longer (5 m) cores obtained during several cruises. Data include water content, unit weight, Atterberg limits (liquid limit, plastic limit, plasticity index), shear strength and compression index, and are used to determine: first, the mass property distribution, according to the main parameters influencing mass-physical properties; the relationships between these properties and the nepheloid layer on the shelf. The shoreline (lagoons) and inner shelf are characterized by low density and shear strength and high water content deposits, due to electrochemical flocculation of the sediment. The outer shelf is blanketed by higher density and shear strength and lower water content deposits generated by normal settling of suspended particles. On the inner shelf, during river peak discharges, a short-term thin bottom layer of "yogurt-like" [ FASS (1985) Geomarine Letters, 4, 147-152; FASS (1986) Continental Shelf Research, 6, 189-208] fluid-mud (unit weight lower than 1.3 mg m -3) is supplied, by a bottom nepheloid layer. During stormy periods, this "yogurt-like" layer (about 10 cm thick) partly disappears by resuspension of suspended particulate matter; this is advected, in the bottom nepheloid layer, over the shelf and the canyons within the upper slope.

  6. Development of the benethic nepheloid layer on the south Texas continental shelf, western Gulf of Mexico

    USGS Publications Warehouse

    Shideler, G.L.

    1981-01-01

    A monitoring study of suspended sediment on the South Texas Continental Shelf indicates that a turbid benthic nepheloid layer is regionally persistent. A sequence of quasi-synoptic measurements of the water column obtained during six cruises in an 18-month period indicates substantial spatial and temporal variability in nepheloidlayer characteristics. Regionally, the thickness of the shelf nepheloid layer increases both seaward and in a convergent alongshelf direction. Greatest thicknesses occur over a muddy substrate, indicating a causal relationship; maximum observed local thickness is 35 m which occurs along the southern shelf break. Analyses of suspended particulate matter in shelf bottom waters indicate mean concentrations ranging from 49 ?? 104 to 111 ?? 104 particle counts/cc; concentrations persistently increase shoreward throughout the region. Bottom particulate matter is predominantly composed of inorganic detritus. Admixtures of organic skeletal particles, primarily diatoms, are generally present but average less than 10% of the total particulate composition. Texturally, the particulate matter in bottom waters is predominantly poorly sorted sediment composed of very fine silt (3.9-7.8 ??m). The variability in nepheloid-layer characteristics indicates a highly dynamic shelf feature. The relationship of nepheloid-layer characteristics to hydrographic and substrate conditions suggests a conceptual model whereby nepheloid-layer development and maintenance are the results of the resuspension of sea-floor sediment. Bottom turbulence is attributed primarily to vertical shear and shoaling progressive internal waves generated by migrating shelf-water masses, especially oceanic frontal systems, and secondarily to shoaling surface gravity waves. ?? 1981.

  7. The nepheloid bottom layer and water masses at the shelf break of the western Ross Sea

    NASA Astrophysics Data System (ADS)

    Capello, Marco; Budillon, Giorgio; Cutroneo, Laura; Tucci, Sergio

    2009-06-01

    In the austral summers of 2000/2001 and 2002/2003 the Italian CLIMA Project carried out two oceanographic cruises along the northwestern margin of the Ross Sea, where the Antarctic Bottom Water forms. Here there is an interaction between the water masses on the sea floor of the outer shelf and slope with a consequent evolution of benthic nepheloid layers and an increase in total particulate matter. We observed three different situations: (a) the presence of triads (bottom structures characterized by a concomitant jump in turbidity, temperature, and salinity data) and high re-suspension phenomena related to the presence of the Circumpolar Deep Water and its mixing with cold, salty shelf waters associated with gravity currents; (b) the absence of triads with high re-suspension, implying that when the gravity currents are no longer active the benthic nepheloid layer may persist until the suspended particles settle to the sea floor, suggesting that the turbidity data can be used to study recent gravity current events; and (c) the absence of turbidity and sediment re-suspension phenomena supports the theory that a steady situation had been re-established and the current interaction no longer occurred or had finished sometime before.

  8. Nepheloid layers and internal waves over continental shelves and slopes

    USGS Publications Warehouse

    Cacchione, D.A.; Drake, D.E.

    1986-01-01

    Theoretical and laboratory results indicate that bottom velocities within shoaling internal gravity waves intensify upslope approximately inversely proportional to the water depth. The elevated velocities (and bottom stresses) caused by shoaling and, possibly, breaking internal waves might explain the generation and maintenance of near-bottom nepheloid zones and attached turbid plumes that have been observed over certain continental shelves and slopes. This process is proposed as an explanation of zones of relatively low transmissibility that emanate from the upper continental slope near Newport submarine canyon off southern California. ?? 1986 Springer-Verlag New York Inc.

  9. Ciliated protists from the nepheloid layer and water column of sites affected by the Deepwater Horizon oil spill in the Northeastern Gulf of Mexico

    NASA Astrophysics Data System (ADS)

    Moss, Joseph A.; McCurry, Chelsea; Tominack, Sarah; Romero, Isabel C.; Hollander, David; Jeffrey, Wade H.; Snyder, Richard A.

    2015-12-01

    Benthic marine protists have been well documented from shallow marine benthic habitats but remain understudied in deeper habitats on continental shelves and slopes, particularly in the Northeastern Gulf of Mexico (NEGOM). This region was affected by a deep water oil well failure (BP-Deepwater Horizon, 2010). The combination of a lack of information on deep sea microbenthic communities and the potential for benthic microbial petroleum mineralization prompted this investigation. Water column and nepheloid layer samples were obtained via Niskin bottles and a multicorer respectively at stations across the NEGOM to: (1) determine whether nepheloid and water column communities are distinct and (2) assess benthic species richness relative to sediment PAH contamination. Phylum specific 18S rRNA gene amplification was used to construct clone libraries of ciliate assemblages. BLAST searches in the NCBI database indicated that a majority (~75%) of the clone sequences corresponded (94-100% similarity) with listed, yet unclassified sequences. Several putative species were common at most site locations and depths. Many known benthic ciliates, such as Uronychia transfuga, Uronychia setigera, and Spirotrachelostyla tani, were common in the nepheloid layer samples and not recovered in water column samples. Ciliated protist species richness increased with PAH levels found in surface sediments, suggesting a positive microbial response to petroleum enrichment of the benthos. The presence of previously unknown microbenthic communites in the nephaloid layer over oceanic clay-silt muds alters our view of microbial processes in the deep sea and merits investigation of the microbial processes and rates of microbial mineralization and biomass production important to global biogeochemistry.

  10. Estuarine sediment transport by gravity-driven movement of the nepheloid layer, Long Island Sound

    USGS Publications Warehouse

    Poppe, L.J.; McMullen, K.Y.; Williams, S.J.; Crocker, J.M.; Doran, E.F.

    2008-01-01

    Interpretation of sidescan-sonar imagery provides evidence that down-slope gravity-driven movement of the nepheloid layer constitutes an important mode of transporting sediment into the basins of north-central Long Island Sound, a major US East Coast estuary. In the Western Basin, this transport mechanism has formed dendritic drainage systems characterized by branching patterns of low backscatter on the seafloor that exceed 7.4 km in length and progressively widen down-slope, reaching widths of over 0.6 km at their southern distal ends. Although much smaller, dendritic patterns of similar morphology are also present in the northwestern part of the Central Basin. Because many contaminants display affinities for adsorption onto fine-grained sediments, and because the Sound is affected by seasonal hypoxia, mechanisms and dispersal pathways by which inorganic and organic sediments are remobilized and transported impact the eventual fate of the contaminants and environmental health of the estuary. ?? Springer-Verlag 2008.

  11. Suspended particulate loads and transports in the nepheloid layer of the abyssal Atlantic Ocean

    USGS Publications Warehouse

    Biscaye, P.E.; Eittreim, S.L.

    1977-01-01

    Vertical profiles of light scattering from over 1000 L-DGO nephelometer stations in the Atlantic Ocean have been used to calculate mass concentrations of suspended particles based on a calibration from the western North American Basin. From these data are plotted the distributions of particulate concentrations at clear water and in the more turbid near-bottom water. Clear water is the broad minimum in concentration and light scattering that occurs at varying mid-depths in the water column. Concentrations at clear water are as much as one-to-two orders of magnitude lower than those in surface water but still reflect a similar geographic distribution: relatively higher concentrations at ocean margins, especially underneath upwelling areas, and the lowest concentrations underneath central gyre areas. These distributions within the clear water reflect surface-water biogenic productivity, lateral injection of particles from shelf areas and surface circulation patterns and require that the combination of downward vertical and horizontal transport processes of particles retain this pattern throughout the upper water column. Below clear water, the distribution of standing crops of suspended particulate concentrations in the lower water column are presented. The integration of mass of all particles per unit area (gross particulate standing crop) reflects a relative distribution similar to that at the surface and at clear water levels, superimposed on which is the strong imprint of boundary currents along the western margins of the Atlantic. Reducing the gross particulate standing crop by the integral of the concentration of clear water yields a net particulate standing crop. The distribution of this reflects primarily the interaction of circulating abyssal waters with the ocean bottom, i.e. a strong nepheloid layer which is coincident with western boundary currents and which diminishes in intensity equatorward. The resuspended particulate loads in the nepheloid layer of the

  12. Observations of intermediate nepheloid layers on the northern California continental margin

    NASA Astrophysics Data System (ADS)

    McPhee-Shaw, E. E.; Sternberg, R. W.; Mullenbach, B.; Ogston, A. S.

    2004-04-01

    Conductivity-temperature-depth and transmissometer surveys were undertaken to investigate the characteristics and seasonal nature of intermediate nepheloid layers (INLs) over the outer shelf and upper slope of the northern California margin, near Eureka, CA. Observed INLs could generally be grouped into one of two categories: INLs that formed and spread seaward from the continental shelf, and INLs generated at continental slope depths greater than 150 m. Shelf INLs, forming between 70 and 150-m depth on the outer shelf and extending seaward 15-20 km past the shelf break, were prevalent during winter and early spring. Continental slope INLs were found during all seasons of the year. Their suspended particulate matter concentration was lower than that of the shelf INLs, and their horizontal extent was 3-7 km seaward from the slope. Mooring data from 450-m depth show strong bottom-trapped semidiurnal internal tidal energy and asymmetry between upslope and downslope semidiurnal motions, indicative of bore-like behavior. These analyses suggest that critical reflection of internal tides is a common feature of the outer continental slope in this region. The location of slope-depth INLs was often observed to coincide with regions where the topographic slope angle was critical for internal tide reflection. In addition, seasonal variability in the span of critical topography over the slope matches seasonal variability in the density of observed INLs over the continental slope. Slope-depth INLs appear to be associated with energetic tidal motions and interaction between internal tides and bathymetry, whereas shelf-depth INLs are likely formed by resuspension events on the outer shelf and subsequent transport offshore by mesoscale circulation processes.

  13. Acquiring Peak Samples from Phytoplankton Thin Layers and Intermediate Nepheloid Layers by an Autonomous Underwater Vehicle with Adaptive Triggering

    NASA Astrophysics Data System (ADS)

    Zhang, Y.; McEwen, R.; Ryan, J. P.; Bellingham, J. G.; Harvey, J.; Vrijenhoek, R.

    2010-12-01

    Phytoplankton thin layers (PTLs) affect many fundamental aspects of coastal ocean ecology including primary productivity, development of harmful algal blooms (HABs) and the survival and growth of zooplankton and fish larvae. Intermediate nepheloid layers (INLs) that contain suspended particulate matter transported from the bottom boundary layer of continental shelves and slopes also affect biogeochemistry and ecology of ocean margins. To better understand the impacts of these types of layers, we have developed an adaptive sampling method for an autonomous underwater vehicle (AUV) to detect a layer (adjusting detection parameters in situ), acquire water samples from peaks in the layer, and acquire control samples outside the layer. We have used the method in a number of field experiments with the AUV Dorado, which is equipped with ten water samplers (called "gulpers"). In real time, the algorithm tracks background levels of fluorescence and optical backscatter and the peaks' baseline to ensure that detection is tuned to the ambient conditions. The algorithm cross-checks fluorescence and backscatter signals to differentiate PTLs from INLs. To capture peak water samples with minimal delay, the algorithm exploits the AUV's sawtooth (i.e., yo-yo) trajectory: the vehicle crosses the detected layer twice in one yo-yo cycle. At the first crossing, it detects the layer's peak and saves its signal height. Sampling is triggered at the second crossing when the signal reaches the saved peak height plus meeting additional timing and depth conditions. The algorithm is also capable of triggering gulpers to acquire control samples outside the layer for comparison with ambient water. The sequence of peak and control samples can be set based on need. In recent AUV Dorado missions, the algorithm triggered the gulpers to acquire peak and control samples from INLs and PTLs in Monterey Bay. Zooplankton analysis of some peak samples showed very high concentrations of mussel and barnacle

  14. Chemical Characterization of Suspended Particulate Organic Matter by Pyrolysis-Gas Chromatography Coupled with Mass Spectrometry and High Performance Liquid Chromatography in the Bottom Nepheloid Layer of the Rhône Delta

    NASA Astrophysics Data System (ADS)

    Gadel, François; Charrière, Bruno; Serve, Léon

    1993-09-01

    During the DYPOL-6 Mission in the Rhône delta the use of a metallic frame provided water samples at three levels of the underlying water column, 2, 1, and 0·5 m above the sea bottom. These sampling levels allowed determination of the characteristics of suspended organic material at the deeper layers of the bottom nepheloid layer and, eventually, their relations with the overlying suspended particulate matter. The results obtained by the measurement of the suspended particulate organic matter, the elemental analysis, the analysis of the main classes of organic compounds by pyrolysis-gas chromatography coupled with mass spectrometry and the determination of phenolic compounds by high performance liquid chromatography (HPLC) emphasized the functional characteristics of the Rhône deltaic system. Near the bottom, the lower water levels of the benthic nepheloid layer showed some obvious biogeochemical gradients related to the location of the sampling station: the amount of pyrolysis-derived phenolic compounds, aromatic hydrocarbons and carbohydrates in the suspended material was high at the stations directly exposed to input of the Rhône River. The stations from the river mouth to offshore areas showed the influence of the Rhône inflow. But sometimes, according to the river regime and the current orientation, the influence of the Liguro-provencal current oriented East-West was noticeable even near the river mouth. In the eastern region of the surveyed area, the stations submitted to this current indicated some specific characteristics: the nepheloid layer, concentrated 1 m above the bottom, had a high particulate organic carbon content and a relatively high amount of phenolic compounds which indicated a possible seagrass ( Posidonia oceanica) origin. At the more seaward stations, although the influence of the river input was always detectable, the suspended particulate matter was less abundant and essentially supplied by the local biogenic input: the lower water

  15. Benthic boundary layer - IOS modelling programme

    NASA Astrophysics Data System (ADS)

    Richards, K. J.

    1983-04-01

    Factors which control the height of the benthic boundary layer in the deep ocean and the residence time of fluid and a tracer within it, were modeled numerically. In one model, the effects of steady and unsteady currents and variations in fluid density are examined. In conditions similar to those observed in the abyssal regions of the E.N. Atlantic the model predicts an average bottom layer height close to the value observed. A second model examines the effects of spatial variations in currents. Due to convergences and divergences produced by these variations, the height of the bottom mixed layer is distorted. Where thinning is large, mixing results in warm patches flanked by benthic fronts. It is proposed that within the warm regions, the bottom mixed layer is exchanged within the ocean above. The residence time of a tracer released within the bottom mixed layer, average value 100 days, is predicted to vary between 20 and 800 days.

  16. The Benthic Boundary Layer: Transport Processes and Biogeochemistry

    NASA Astrophysics Data System (ADS)

    van Duren, Luca A.; Middelburg, Jack J.

    Interdisciplinary research is certainly one of the current buzzwords that needs to be incorporated in virtually every grant proposal. The idea that integration of different scientific fields is a prerequisite for progress in Earth sciences is now well recognized. The benthic boundary layer (BBL) is one area of research in which physicists, chemists, biologists, geologists, and engineers have worked in close and fruitful cooperation for several decades. The BBL comprises the near-bottom layer of water, the sediment-water interface, and the top layer of sediment that is directly influenced by the overlying water. In 1974, a BBL conference in France resulted in a book titled The Benthic Boundary Layer edited by I.N. McCave. This publication contained contributions from scientists from a wide range of disciplines and gave an overview of the state-of-the-art of BBL research. However, science has moved on in the past 25 years. Significant conceptual and technological progress has been made, and it is definitely time for an update.

  17. Particle fluxes, benthic processes and the palaeoenvironmental record in the Northern Weddell Sea

    NASA Astrophysics Data System (ADS)

    Pudsey, Carol J.; King, Penny

    1997-11-01

    At the northern edge of the Weddell Gyre, Antarctica, fine-grained sediments accumulate beneath eastward-flowing Weddell Sea Bottom Water. We report on sediment trap material and core tops from four sites, with relevant water-column data. In this cold, low-productivity oceanographic setting it is the processes in the benthic nepheloid layer (resuspension, transport, winnowing of fines) and in the upper few cm of sediment (bioturbation, dissolution of biogenic silica and carbonate, degradation of organic matter) that dominate the palaeoenvironmental record. Biogenic productivity is low and seasonal because of sea-ice cover; terrigenous sediment is supplied by resuspension of Weddell Sea slope and rise sediments and by ice-rafting. The benthic nepheloid layer is up to 150 m thick, with particulate matter concentrations of up to 0.51 mg/l. Sediment traps moored for 2 years 827 m above the seabed collected mainly biogenic opal with well-preserved and diverse diatoms and radiolarians. Traps 21 m above the seabed recorded additional high fluxes of terrigenous silt and clay. Core tops are terrigenous with very little organic matter or opal except at the northernmost site and a very restricted diatom assemblage. Core tops consist of silty clay or sandy silty clay, depending on current regime; the proportion of fine sand is related to the annual frequency of high ( > 15 cm/sec) current speeds at each site. AMS 14C dates on organic carbon in sediment traps are 965±50 and 1895±55 radiocarbon years, reflecting the high reservoir age of Southern Ocean surface waters. Core top ages of particulate organic carbon are 10500 and 13000 calendar years B.P. These high ages are related to the glacial-age source of resuspended slope and rise sediments. Cores from this area contain a textural record of Weddell Sea Bottom Water flow, but only fragmentary data on palaeo-surface conditions.

  18. An instrument system for monitoring and sampling suspended sediment in the benthic boundary layer

    USGS Publications Warehouse

    Sternberg, R.W.; Johnson, R.V.; Cacchione, D.A.; Drake, D.E.

    1986-01-01

    An instrument system has been constructed that can monitor and sample suspended sediment distributions in the benthic boundary layer. It consists of miniature nephelometers and suspended sediment samplers placed within one meter of the seabed. The system is capable of continuously monitoring suspended sediment profiles at eight levels between 14 and 100 cm above the seabed and collecting suspended sediment samples at four levels (20, 50, 70 and 100 cm) at three times during a deployment period. The suspended sediment system is designed to fit onto the instrumented tripod GEOPROBE which contains four electromagnetic current meters, pressure sensor, bottom stereo camera, two temperature sensors, transmissometer, and a Savonius rotor current meter. Sensor operation, data recording, and sediment sampling events are synchronized. Thus detailed measurements of the near-bottom flow conditions are made concurrently with suspended sediment measurements. The combined system has been used in sediment transporting environments within San Francisco Bay, California, and Puget Sound, Washington. ?? 1986.

  19. Modeling basic features of biogeochemical structure of water column, bottom boundary layer and benthic boundary layer in changeable redox conditions

    NASA Astrophysics Data System (ADS)

    Yakushev, Evgeniy

    2013-04-01

    Climate Change affects oxygen depletion and leads to spreading of the bottom areas with hypoxic and anoxic conditions in the coastal areas of the seas and inland waters. This work aimed in estimation of a role of changes of redox conditions in the biogeochemical structure there. We use a 1-dimensional C-N-P-Si-O-S-Mn-Fe vertical transport-reaction model describing the water column, bottom boundary layer and benthic boundary layer with biogeochemical block simulating redox conditions changeability. A biogeochemical block is based on ROLM (RedOx Layer Model), that was constructed to simulate basic features of the water column biogeochemical structure changes in oxic, anoxic and changeable conditions (Yakushev et al., 2007). Organic matter formation and decay, reduction and oxidation of species of nitrogen, sulfur, manganese, iron, and the transformation of phosphorus species are parameterized in the model. ROLM includes a simplified ecological model with phytoplankton, zooplankton, aerobic autotrophic and heterotrophic bacteria, anaerobic autotrophic and heterotrophic bacteria. We simulate changes in the parameters distributions and fluxes connected with the vertical displacement of redox interface from the sediments to the water.

  20. Laboratory measurements of scalar and momentum structure in turbulent aquatic benthic boundary layers

    NASA Astrophysics Data System (ADS)

    Dombroski, Daniel Edward

    In aquatic benthic environments, hydrodynamic transport of mass and momentum have shaped the evolution of form-function relationships. Animals whose life cycle depends on success in such environments have developed the biological structure and behavioral mechanisms to sustain dynamic stresses and complex chemical signals. It has become increasingly clear that understanding the ecology of these organisms is dependent on examining the complexities of the turbulent environment. In this dissertation, hydrodynamics and the structure of chemical signals within turbulent boundary layer flows are examined in the context of natural and biological systems. Experiments were conducted in the benthic region of a water flume using a combination of point-measurement and full-field imaging techniques. There are three areas of focus within the complete body of work: (1) The accuracy of an acoustic measurement technique commonly used in natural flows was evaluated. Errors in the technique, primarily attributed to a sampling volume that is large relative to the scales of motion in turbulent flows, were found to be larger than and extend farther from the bed than previously reported. (2) A three-dimensional laser-based imaging system was developed for quantifying turbulent scalar structure. The system was employed to study the topology and orientation of structure within a bed-level, passively released scalar plume. (3) Hydrodynamic stresses were measured near marine fouling communities in a study aimed at predicting larval settlement probabilities. Turbulent stresses, and by extension, the suitability of microhabitats, were found to be highly dependent on local topography and outer-scale flow conditions. This body of work advances the field of experimental fluid mechanics by contributing to the development of methods for quantifying turbulent flows, as well as furthering current understanding of the capabilities and limitations associated with new and existing techniques. Statistical

  1. Microbial activities at the benthic boundary layer in the Aegean Sea

    NASA Astrophysics Data System (ADS)

    Bianchi, A.; Tholosan, O.; Garcin, J.; Polychronaki, T.; Tselepides, A.; Buscail, R.; Duineveld, G.

    2003-05-01

    During the Aegean Sea component of the EU MTP-MATER project, benthic samples were acquired along a depth gradient from two continental margins in the Aegean Sea. Sampling was undertaken during spring and summer 1997 and the microbial metabolic activities measured (Vmax for aminopeptidase activity, 14C-glutamate respiration and assimilation) displayed seasonal variability even in deep-sea conditions. The metabolic rates encountered in the North Aegean (average depth 566±234 m), were approximately five-fold higher than in the deeper (1336±140 m) Southern part of the Aegean. The aminopeptidase rates, however, were the exception with higher values recorded in the more oligotrophic sediments of the Southern stations (1383±152 vs. 766±297 nmol MCA cm -2 h -1). A discrepancy in bacterial metabolism also appeared in the near bottom waters. In the Southern stations, 80% of the glutamate uptake was used for energy yielding processes and only 20% devoted to biomass production, while in the North Aegean, most of the used glutamate was incorporated into bacterial cells. During the early burial stages, bacterial mineralization rates estimated from 14C-glutamate respiration decreased drastically compared to the rates of biopolymer hydrolysis estimated by aminopeptidase assays. Thus, at the 2-cm depth layer, these rates were only 32 and up to 77% of the corresponding average values, respectively, in the superficial layer. Such a discrepancy between the evolution of these two metabolic activities is possibly due to the rapid removal of readily utilizable monomers in the surface deposits. The correlation between bacterial respiration and total organic carbon, or total organic nitrogen, is higher in the surficial sediment (0-2 and 2-4 cm) than in the underlying layer. Conversely, it is only at 4-cm depth layer that the hydrolysis rates appear correlated with organic carbon and nitrogen concentrations. This pattern confirms the drastic degradation of organic matter during the

  2. Trophic relationships of deep-sea calanoid copepods from the benthic boundary layer of the Santa Catalina Basin, California

    NASA Astrophysics Data System (ADS)

    Gowing, Marcia M.; Wishner, Karen F.

    1986-07-01

    Benthopelagic zooplankton were collected and preserved in situ in the benthic boundary layer of the Santa Catalina Basin, using a multiple sampling opening-closing net system attached to the DSRV Alvin. Gut content analysis performed with transmission electron microscopy (TEM) showed that the majority of benthopelagic calanoid copepods examined were predominantly detritivores. They had ingested detritus and associated bacteria, including metal-precipitating bacteria; no attached enteric bacteria were observed in the copepods' guts. The gut particles indicated generalized feeding and qualitatively resembled material present in the environment at the time of collection, i.e. suspended particles, large fecal pellets, particles from the surface layer of the sediment, and phaeodia of phaeodarian radiolarians. TEM was necessary for identifying some of the amorphous material in copepod guts as either digested tissue or detrital material; some of the amorphous material was unidentifiable even with the resolution of TEM. TEM was also essential for detecting metal-precipitating bacteria and their capsules from the copepod guts and from particles in the water. Because they ingest metal-precipitating bacteria, detritivorous copepods may influence the distribution of metals in the ocean.

  3. Two-dimensional distribution of living benthic foraminifera in anoxic sediment layers of an estuarine mudflat (Loire estuary, France)

    NASA Astrophysics Data System (ADS)

    Thibault de Chanvalon, A.; Metzger, E.; Mouret, A.; Cesbron, F.; Knoery, J.; Rozuel, E.; Launeau, P.; Nardelli, M. P.; Jorissen, F. J.; Geslin, E.

    2015-10-01

    We present a new rapid and accurate protocol to simultaneously sample benthic living foraminifera in two dimensions in a centimetre-scale vertical grid and dissolved iron and phosphorus in two dimensions at high resolution (200 μm). Such an approach appears crucial for the study of foraminiferal ecology in highly dynamic and heterogeneous sedimentary systems, where dissolved iron shows a strong variability at the centimetre scale. On the studied intertidal mudflat of the Loire estuary, foraminiferal faunas are dominated by Ammonia tepida, which accounts for 92 % of the living (CellTracker Green(CTG)-labelled) assemblage. The vertical distribution shows a maximum density in the oxygenated 0-0.4 cm surface layer. A sharp decrease is observed in the next 2 cm, followed by a second, well-defined maximum in the suboxic sediment layer (3-8 cm depth). The presented method yields new information concerning the 2-D distribution of living A. tepida in suboxic layers. First, the identification of recent burrows by visual observation of the sediment cross section and the burrowing activity as deduced from the dissolved iron spatial distribution show no direct relation to the distribution of A. tepida at the centimetre scale. This lack of relation appears contradictory to previous studies (Aller and Aller, 1986; Berkeley et al., 2007). Next, the heterogeneity of A. tepida in the 3-8 cm depth layer was quantified by means of Moran's index to identify the scale of parameters controlling the A. tepida distribution. The results reveal horizontal patches with a characteristic length of 1-2 cm. These patches correspond to areas enriched in dissolved iron likely generated by anaerobic degradation of labile organic matter. These results suggest that the routine application of our new sampling strategy could yield important new insights about foraminiferal life strategies, improving our understanding of the role of these organisms in coastal marine ecosystems.

  4. High Energy Benthic Boundary Layer Experiment (HEBBLE): Preliminary program plan and conceptual design

    NASA Technical Reports Server (NTRS)

    Frewing, K.

    1980-01-01

    Deep sea processes of flow-sediment interaction, particularly the role of high energy ocean bottom current events in forming the seafloor topography, transporting material, and mixing the bottom of the water column are examined. A series of observations at and near the sea bottom, in water depths of 4 to 5 km, in areas of the western North Atlantic where high energy current events occur, include site surveys and physical reconnaissance to identify suitable areas and positions, and one or more six month experiments to investigate temporal and spatial variations of high energy events within the boundary layer and their interaction with the seabed. Descriptions of proposed HEBBLE activities are included, with emphasis on technology transfer to the oceanographic community through design, fabrication, testing, and operation of an instrumented ocean bottom lander.

  5. Shining light on benthic macroalgae: mechanisms of complementarity in layered macroalgal assemblages.

    PubMed

    Tait, Leigh W; Hawes, Ian; Schiel, David R

    2014-01-01

    Phototrophs underpin most ecosystem processes, but to do this they need sufficient light. This critical resource, however, is compromised along many marine shores by increased loads of sediments and nutrients from degraded inland habitats. Increased attenuation of total irradiance within coastal water columns due to turbidity is known to reduce species' depth limits and affect the taxonomic structure and architecture of algal-dominated assemblages, but virtually no attention has been paid to the potential for changes in spectral quality of light energy to impact production dynamics. Pioneering studies over 70 years ago showed how different pigmentation of red, green and brown algae affected absorption spectra, action spectra, and photosynthetic efficiency across the PAR (photosynthetically active radiation) spectrum. Little of this, however, has found its way into ecological syntheses of the impacts of optically active contaminants on coastal macroalgal communities. Here we test the ability of macroalgal assemblages composed of multiple functional groups (including representatives from the chlorophyta, rhodophyta and phaeophyta) to use the total light resource, including different light wavelengths and examine the effects of suspended sediments on the penetration and spectral quality of light in coastal waters. We show that assemblages composed of multiple functional groups are better able to use light throughout the PAR spectrum. Macroalgal assemblages with four sub-canopy species were between 50-75% more productive than assemblages with only one or two sub-canopy species. Furthermore, attenuation of the PAR spectrum showed both a loss of quanta and a shift in spectral distribution with depth across coastal waters of different clarity, with consequences to productivity dynamics of diverse layered assemblages. The processes of light complementarity may help provide a mechanistic understanding of how altered turbidity affects macroalgal assemblages in coastal waters

  6. Shining light on benthic macroalgae: mechanisms of complementarity in layered macroalgal assemblages.

    PubMed

    Tait, Leigh W; Hawes, Ian; Schiel, David R

    2014-01-01

    Phototrophs underpin most ecosystem processes, but to do this they need sufficient light. This critical resource, however, is compromised along many marine shores by increased loads of sediments and nutrients from degraded inland habitats. Increased attenuation of total irradiance within coastal water columns due to turbidity is known to reduce species' depth limits and affect the taxonomic structure and architecture of algal-dominated assemblages, but virtually no attention has been paid to the potential for changes in spectral quality of light energy to impact production dynamics. Pioneering studies over 70 years ago showed how different pigmentation of red, green and brown algae affected absorption spectra, action spectra, and photosynthetic efficiency across the PAR (photosynthetically active radiation) spectrum. Little of this, however, has found its way into ecological syntheses of the impacts of optically active contaminants on coastal macroalgal communities. Here we test the ability of macroalgal assemblages composed of multiple functional groups (including representatives from the chlorophyta, rhodophyta and phaeophyta) to use the total light resource, including different light wavelengths and examine the effects of suspended sediments on the penetration and spectral quality of light in coastal waters. We show that assemblages composed of multiple functional groups are better able to use light throughout the PAR spectrum. Macroalgal assemblages with four sub-canopy species were between 50-75% more productive than assemblages with only one or two sub-canopy species. Furthermore, attenuation of the PAR spectrum showed both a loss of quanta and a shift in spectral distribution with depth across coastal waters of different clarity, with consequences to productivity dynamics of diverse layered assemblages. The processes of light complementarity may help provide a mechanistic understanding of how altered turbidity affects macroalgal assemblages in coastal waters

  7. Shining Light on Benthic Macroalgae: Mechanisms of Complementarity in Layered Macroalgal Assemblages

    PubMed Central

    Tait, Leigh W.; Hawes, Ian; Schiel, David R.

    2014-01-01

    Phototrophs underpin most ecosystem processes, but to do this they need sufficient light. This critical resource, however, is compromised along many marine shores by increased loads of sediments and nutrients from degraded inland habitats. Increased attenuation of total irradiance within coastal water columns due to turbidity is known to reduce species' depth limits and affect the taxonomic structure and architecture of algal-dominated assemblages, but virtually no attention has been paid to the potential for changes in spectral quality of light energy to impact production dynamics. Pioneering studies over 70 years ago showed how different pigmentation of red, green and brown algae affected absorption spectra, action spectra, and photosynthetic efficiency across the PAR (photosynthetically active radiation) spectrum. Little of this, however, has found its way into ecological syntheses of the impacts of optically active contaminants on coastal macroalgal communities. Here we test the ability of macroalgal assemblages composed of multiple functional groups (including representatives from the chlorophyta, rhodophyta and phaeophyta) to use the total light resource, including different light wavelengths and examine the effects of suspended sediments on the penetration and spectral quality of light in coastal waters. We show that assemblages composed of multiple functional groups are better able to use light throughout the PAR spectrum. Macroalgal assemblages with four sub-canopy species were between 50–75% more productive than assemblages with only one or two sub-canopy species. Furthermore, attenuation of the PAR spectrum showed both a loss of quanta and a shift in spectral distribution with depth across coastal waters of different clarity, with consequences to productivity dynamics of diverse layered assemblages. The processes of light complementarity may help provide a mechanistic understanding of how altered turbidity affects macroalgal assemblages in coastal

  8. Diapycnal nutrient fluxes across the benthic boundary layers at the continental slopes off Peru and Mauritania based on 224Ra/223Ra-ratios

    NASA Astrophysics Data System (ADS)

    Reichert, P.; Scholten, J. C.; Eisenhauer, A.; Miquel, J. C.; Gasser, B.; Liebetrau, V.; Sommer, S.; Dengler, M.; Bryant, L. D.

    2014-12-01

    Marine sediments may act as sources and/or sinks of nutrients in oxygen minimum zones (OMZs) where solute fluxes between sediments and the above water column are believed to be an important component for the bioproductivity in the mixed layer. However, solute fluxes between sediments and the water column above are difficult to obtain. We determined the diapycnal nutrient fluxes across the benthic boundary layer at the OMZs off Peru and Mauritania using nutrient concentration profiles and vertical diffusion coefficients derived from 224Ra/223Ra isotope ratios. The radium isotopes 223Ra (half-life: 11.4 days) and 224Ra (half-life: 3.66 days) are produced in sediments by radioactive decay of 227Th and 228Th ,respectively: Diffusion of radium out of the sediments results in gradients of 224Ra/223Ra above the sediments; and these gradients may be used to estimate vertical diffusion coefficients. We determined 224Ra/223Ra along two transects at the continental slopes off Peru (12° S) and off Mauritania (18° N) in water depths between 65m - 1000mand 53m - 1100m, respectively. For the 223Ra/224Ra sampling we used acrylic fibers/cartridges coated with MnO2. The Mn-fibers were attached to benthic landers (moored for ~ 24 hours at the sea floor) and the Mn-cartridges were placed in series on several in-situ filtration pumps (Challenger Oceanic and McLane pumps). 223Ra and 224Ra were measured on-board using a delayed coincidence counting system (RaDeCC). In our presentation we will present the 224Ra/223Ra distribution along these transects investigated and we will compare the diapycnal radium-derived nutrient fluxes with those determined using benthic chambers and microstructure measurements.

  9. Benthic processes affecting contaminant transport in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Kuwabara, James S.; Topping, Brent R.; Carter, James L.; Carlson, Rick A; Parchaso, Francis; Fend, Steven V.; Stauffer-Olsen, Natalie; Manning, Andrew J.; Land, Jennie M.

    2016-09-30

    characteristics and settling velocities were analyzed from the water column near the surface (sample dp_10) and lakebed (sample dp_90) at two lake sites (open-lake site ML and littoral site LS01). The term “floc” refers herein to suspended particles that may aggregate or disaggregate to change in size, composition, and settling velocity. During pre-bloom (May) conditions, where maximum suspended particulate matter concentration (SPMC) was 140 milligrams per liter (mg L−1) was now observed at site LS01 in close proximity to the bed, where Dmean peaked at 305 μm, and the corresponding Wsmean was 3.9 millimeters per second (mm s−1). The high near-bed SPMC (828 mg L−1) experienced during post-bloom October 2015 at LS01 formed a benthic nepheloid layer (BNL) above the lake’s bed. Numerous low density, fast settling macrofloc-sized organic aggregates (D >160 μm) were observed (some up to 1 mm in size) near bed at LS01 both during the bloom and post-bloom conditions; many of these flocs displayed fibrous organic structures. In terms of mass settling fluxes, the post-bloom BNL produced a total MSF of 4,139 milligrams per square meter per second (mg m−2 s−1) (92.1 percent of MSF credited to the macrofloc-sized organic aggregates/cyanobacterial colonies); that was nearly three times the corresponding near-bed settling flux observed during the July 2015 bloom and 360 times greater than the pre-bloom conditions from May 2015 (98.8 percent and 14 percent of MSF credited to the macrofloc-sized fractions for those respective months). Such changes in the near-bed settling flux demonstrate the highly significant seasonal effects that the AFA bloom has on the floc depositional fluxes in UKL and highlights the importance of seasonal monitoring of these conditions in order to correctly parameterize the wide range in depositional characteristics and floc properties measured throughout UKL. Collectively, floc populations observed within UKL demonstrated a wide range in settling

  10. Benthic cyanobacterial mats in the high arctic: multi-layer structure and fluorescence responses to osmotic stress.

    PubMed

    Lionard, Marie; Péquin, Bérangère; Lovejoy, Connie; Vincent, Warwick F

    2012-01-01

    Cyanobacterial mats are often a major biological component of extreme aquatic ecosystems, and in polar lakes and streams they may account for the dominant fraction of total ecosystem biomass and productivity. In this study we examined the vertical structure and physiology of Arctic microbial mats relative to the question of how these communities may respond to ongoing environmental change. The mats were sampled from Ward Hunt Lake (83°5.297'N, 74°9.985'W) at the northern coast of Arctic Canada, and were composed of three visibly distinct layers. Microsensor profiling showed that there were strong gradients in oxygen within each layer, with an overall decrease from 100% saturation at the mat surface to 0%, at the bottom, accompanied by an increase of 0.6 pH units down the profile. Gene clone libraries (16S rRNA) revealed the presence of Oscillatorian sequences throughout the mat, while Nostoc related species dominated the two upper layers, and Nostocales and Synechococcales sequences were common in the bottom layer. High performance liquid chromatography analyses showed a parallel gradient in pigments, from high concentrations of UV-screening scytonemin in the upper layer to increasing zeaxanthin and myxoxanthin in the bottom layer, and an overall shift from photoprotective to photosynthetic carotenoids down the profile. Climate change is likely to be accompanied by lake level fluctuations and evaporative concentration of salts, and thus increased osmotic stress of the littoral mat communities. To assess the cellular capacity to tolerate increasing osmolarity on physiology and cell membrane integrity, mat sections were exposed to a gradient of increasing salinities, and PAM measurements of in vivo chlorophyll fluorescence were made to assess changes in maximum quantum yield. The results showed that the mats were tolerant of up to a 46-fold increase in salinity. These features imply that cyanobacterial mats are resilient to ongoing climate change, and that in the

  11. Seasonal variation in concentration, size, and settling velocity of muddy marine flocs in the benthic boundary layer

    NASA Astrophysics Data System (ADS)

    Fettweis, Michael; Baeye, Matthias

    2015-08-01

    Suspended Particulate Matter (SPM) concentration profiles of the lowest 2 m of the water column and particle size distribution at 2 m above the bed were measured in a coastal turbidity maximum area (southern North Sea) during more than 700 days between 2006 and 2013. The long-term data series of SPM concentration, floc size, and settling velocity have been ensemble averaged according to tidal range, alongshore residual flow direction, and season, in order to investigate the seasonal SPM dynamics and its relation with physical and biological processes. The data show that the SPM is more concentrated in the near-bed layer in summer, whereas in winter, the SPM is better mixed throughout the water column. The decrease of the SPM concentration in the water column during summer is compensated by a higher near-bed concentration indicating that a significant part of the SPM remains in the area during summer rather than being advected out of it. The opposite seasonality between near-bed layer and water column has to our knowledge not yet been presented in literature. Physical effects such as wave heights, wind climate, or storms have a weak correlation with the observed seasonality. The argument to favor microbial activity as main driver of the seasonality lies in the observed variations in floc size and settling velocity. On average, the flocs are larger and thus settling velocities higher in summer than winter.

  12. Trophic interactions in the benthic boundary layer of the Beaufort Sea shelf, Arctic Ocean: Combining bulk stable isotope and fatty acid signatures

    NASA Astrophysics Data System (ADS)

    Connelly, Tara L.; Deibel, Don; Parrish, Christopher C.

    2014-01-01

    The food web structure and diets of 26 taxa of benthic boundary layer (BBL) zooplankton on the Beaufort Sea shelf were studied using carbon and nitrogen stable isotopes and fatty acids. Mean δ15N values ranged from 7.3‰ for the amphipod Melita formosa to 14.9‰ for an unidentified polychaete, suggesting that taxa sampled came from three trophic levels. For 8 taxa, the lightest carbon signature occurred near the mouth of the Mackenzie River. Stable isotope ratios helped clarify the origin of signature fatty acids. Levels of certain polyunsaturated fatty acids (PUFA) were negatively correlated with δ15N, with the exception of 22:6ω3, which was positively correlated with δ15N, suggesting that this essential PUFA was retained through the food web. Discriminant analysis proved to be a powerful tool, predicting taxa from fatty acid profiles with 99% accuracy, and revealing strong phylogenetic trends in fatty acid profiles. The amphipod Arrhis phyllonyx had higher levels of ω6 PUFA, especially 20:4ω6 with several possible sources, than other peracarid crustaceans. The holothurian had high levels of odd numbered and branched chain fatty acids, indicative of bacterial consumption, while fatty acids of phytoplankton origin were important discriminants for Calanus hyperboreus and the chaetognaths Eukrohnia hamata and Parasagitta elegans. This relationship indicates that the conventional phytoplankton-copepod-chaetognath food web found in the water column also exists in the BBL. This observation, as well as generally low δ15N and high levels of certain PUFA in samples with lower δ15N, strongly suggests that BBL zooplankton on the Beaufort Sea shelf have access to fresh material of phytoplankton origin either by feeding on sedimenting matter or by active migration to surface waters.

  13. Marine benthic dynamics

    SciTech Connect

    Tenore, K.R.; Coull, B.C.

    1980-01-01

    The proceedings from this symposium contain an overview of the benthic ecosystem. The structure, population dynamics, and secondary production of benthic ecosystems are discussed in light of the role of detritus and nutrient cycling in the food chain. The twenty three articles of presentation are grouped by categories of secondary production, population studies, nutrient cycling, and detritus and are summarized and indexed with an abstract for each presentation. (DS)

  14. Benthic foraminiferal thanatocoenoses from the Cap-Ferret Canyon area (NE Atlantic): A complex interplay between hydro-sedimentary and biological processes

    NASA Astrophysics Data System (ADS)

    Duros, P.; Jorissen, F. J.; Cesbron, F.; Zaragosi, S.; Schmidt, S.; Metzger, E.; Fontanier, C.

    2014-06-01

    Benthic foraminiferal thanatocoenoses from the Cap-Ferret Canyon area were studied in the >150-μm fraction of 4-5 cm deep sediment levels, at 13 stations. The shallowest station (151 m depth) is located at the shelf break, close to the canyon head. All other stations are located along two bathymetric transects: seven stations along the canyon axis between 300 and 3000 m depth, and five stations from 300 m to 2000 m depth along the southern flank of the canyon. The comparison between the live (Rose-Bengal-stained) and dead assemblages shows that biological (i.e. population dynamic) and taphonomic processes (i.e. test destruction, transport) generate important discrepancies between live and dead assemblages. An important question is, to what degree post-mortem transport and redeposition of foraminiferal tests contribute to the difference between living and dead assemblages? The composition of the thanatocoenoses (<1% of neritic species) indicates that there is no substantial transport of shells >150 μm from the inner continental shelf to the Cap-Ferret Canyon axis. However, transport of tests from outer shelf or upper canyon axis towards deeper sites occurs, as indicated by an increase of diversity indices of the dead fauna along the canyon axis. Moreover, some species (e.g., Cassidulina carinata) are observed in the living fauna restricted to the shallow sites, but occur in important amounts in the dead fauna at deeper stations, suggesting that these taxa have been transported from upper canyon stations toward deeper sites. Since Cap-Ferret Canyon is inactive in terms of massive sediment transport (i.e. gravity events), downslope transport of foraminiferal tests probably takes place in nepheloid layers. Downslope transports of foraminiferal tests may create important biases for the utilisation of paleoceanographic proxies using the assemblage characteristics and/or the geochemical composition of selected species. However, the study of dead assemblages along a

  15. Layers

    NASA Astrophysics Data System (ADS)

    Hong, K. J.; Jeong, T. S.; Youn, C. J.

    2014-09-01

    The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states Γ4( z), Γ5( x), and Γ5( y) to the conduction-band state Γ1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states Γ4( z), Γ5( x), and Γ5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

  16. INDIVIDUAL TURBULENT CELL INTERACTION: BASIS FOR BOUNDARY LAYER ESTABLISHMENT

    EPA Science Inventory

    Boundary layers are important in determining the forces on objects in flowing fluids, mixing characteristics, and other phenomena. For example, benthic boundary layers are frequently active resuspension layers that determine bottom turbidity and transniissivity. Traditionally, bo...

  17. Novel developments in benthic modelling to address scientific and policy challenges

    NASA Astrophysics Data System (ADS)

    Lessin, Gennadi; Artioli, Yuri; Bruggeman, Jorn; Aldridge, John; Blackford, Jerry

    2016-04-01

    Understanding the role of benthic systems in supporting, regulating and providing marine ecosystem services requires better understanding of their functioning and their response and resilience to stressors. Novel observational methods for the investigation of dynamics of benthic-pelagic coupling in shelf seas are being developed and new data is being collected. Therefore there is an increasing demand for robust representation of benthic processes in marine biogeochemical and ecosystem models, which would improve our understanding of whole systems and benthic-pelagic coupling, rather than act as mere closure terms for pelagic models. However, for several decades development of benthic models has lagged behind their pelagic counterparts. To address contemporary scientific, policy and societal challenges, the biogeochemical and ecological model ERSEM (European Regional Seas Ecosystem Model), including its benthic sub-model, was recently recoded in a scalable and modular format adopting the approach of FABM (Framework for Aquatic Biogeochemical Models). Within the Shelf Sea Biogeochemistry research programme, a series of additional processes have been included, such as a sedimentary carbonate system, a resuspendable fluff layer, and the simulation of advective sediments. It was shown that the inclusion of these processes changes the dynamics of benthic-pelagic fluxes as well as modifying the benthic food web. Comparison of model results with in-situ data demonstrated a general improvement of model performance and highlighted the importance of the benthic system in overall ecosystem dynamics. As an example, our simulations have shown that inclusion of a resuspendable fluff layer facilitates regeneration of inorganic nutrients in the water column due to degradation of resuspended organic material by pelagic bacteria. Moreover, the composition of fluff was found to be important for trophic interactions, and therefore indirectly affects benthic community composition. Where

  18. Carbon fate in a large temperate human-impacted river system: Focus on benthic dynamics

    NASA Astrophysics Data System (ADS)

    Vilmin, Lauriane; Flipo, Nicolas; Escoffier, Nicolas; Rocher, Vincent; Groleau, Alexis

    2016-07-01

    Fluvial networks play an important role in regional and global carbon (C) budgets. The Seine River, from the Paris urban area to the entrance of its estuary (220 km), is studied here as an example of a large human-impacted river system subject to temperate climatic conditions. We assess organic C (OC) budgets upstream and downstream from one of the world's largest wastewater treatment plants and for different hydrological conditions using a hydrobiogeochemical model. The fine representation of sediment accumulation on the river bed allows for the quantification of pelagic and benthic effects on OC export toward the estuary and on river metabolism (i.e., net CO2 production). OC export is significantly affected by benthic dynamics during the driest periods, when 25% of the inputs to the system is transformed or stored in the sediment layer. Benthic processes also substantially affect river metabolism under any hydrological condition. On average, benthic respiration accounts for one third of the total river respiration along the studied stretch (0.27 out of 0.86 g C m-2 d-1). Even though the importance of benthic processes was already acknowledged by the scientific community for headwater streams, these results stress the major influence of benthic dynamics, and thus of physical processes such as sedimentation and resuspension, on C cycling in downstream river systems. It opens the door to new developments in the quantification of C emissions by global models, whereby biogeochemical processing and benthic dynamics should be taken into account.

  19. Assessing benthic oxygen fluxes in oligotrophic deep sea sediments (HAUSGARTEN observatory)

    NASA Astrophysics Data System (ADS)

    Donis, Daphne; McGinnis, Daniel F.; Holtappels, Moritz; Felden, Janine; Wenzhoefer, Frank

    2016-05-01

    Benthic oxygen fluxes, an established proxy for total organic carbon mineralization, were investigated in oligotrophic deep sea sediments. We used three different in situ technologies to estimate the benthic oxygen fluxes at an Arctic deep sea site (2500 m depth, HAUSGARTEN observatory) with limiting conditions of low oxygen gradients and fluxes, low turbulence and low particle content in the benthic boundary layer. The resolved eddy covariance turbulent oxygen flux (-0.9±0.2 (SD) mmol O2 m-2 d-1) compared well with simultaneous dissolved oxygen flux measurements carried out with a microprofiler (-1.02±0.3 (SD) mmol O2 m-2 d-1) and total oxygen uptake obtained by benthic chamber incubations (-1.1±0.1 (SD) mmol O2 m-2 d-1). The agreement between these different techniques revealed that microbial-mediated oxygen consumption was dominant at this site. The average benthic flux equals a carbon mineralization rate of 4.3 g C m-2 yr-1, which exceeds the annual sedimentation of particulate organic matter measured by sediment traps. The present study represents a detailed comparison of different in situ technologies for benthic flux measurements at different spatial scales in oligotrophic deep sea sediments. The use of eddy covariance, so far rarely used for deep sea investigations, is presented in detail.

  20. Benthic protists: the under-charted majority.

    PubMed

    Forster, Dominik; Dunthorn, Micah; Mahé, Fréderic; Dolan, John R; Audic, Stéphane; Bass, David; Bittner, Lucie; Boutte, Christophe; Christen, Richard; Claverie, Jean-Michel; Decelle, Johan; Edvardsen, Bente; Egge, Elianne; Eikrem, Wenche; Gobet, Angélique; Kooistra, Wiebe H C F; Logares, Ramiro; Massana, Ramon; Montresor, Marina; Not, Fabrice; Ogata, Hiroyuki; Pawlowski, Jan; Pernice, Massimo C; Romac, Sarah; Shalchian-Tabrizi, Kamran; Simon, Nathalie; Richards, Thomas A; Santini, Sébastien; Sarno, Diana; Siano, Raffaele; Vaulot, Daniel; Wincker, Patrick; Zingone, Adriana; de Vargas, Colomban; Stoeck, Thorsten

    2016-08-01

    Marine protist diversity inventories have largely focused on planktonic environments, while benthic protists have received relatively little attention. We therefore hypothesize that current diversity surveys have only skimmed the surface of protist diversity in marine sediments, which may harbor greater diversity than planktonic environments. We tested this by analyzing sequences of the hypervariable V4 18S rRNA from benthic and planktonic protist communities sampled in European coastal regions. Despite a similar number of OTUs in both realms, richness estimations indicated that we recovered at least 70% of the diversity in planktonic protist communities, but only 33% in benthic communities. There was also little overlap of OTUs between planktonic and benthic communities, as well as between separate benthic communities. We argue that these patterns reflect the heterogeneity and diversity of benthic habitats. A comparison of all OTUs against the Protist Ribosomal Reference database showed that a higher proportion of benthic than planktonic protist diversity is missing from public databases; similar results were obtained by comparing all OTUs against environmental references from NCBI's Short Read Archive. We suggest that the benthic realm may therefore be the world's largest reservoir of marine protist diversity, with most taxa at present undescribed.

  1. Benthic phosphorus regeneration in the Potomac River Estuary

    USGS Publications Warehouse

    Callender, E.

    1982-01-01

    The flux of dissolved reactive phosphate from Potomac riverine and estuarine sediments is controlled by processes occurring at the water-sediment interface and within surficial sediment. In situ benthic fluxes (0.1 to 2.0 mmoles m-2 day-1) are generally five to ten times higher than calculated diffusive fluxes (0.020 to 0.30 mmoles m-2 day-1). The discrepancy between the two flux estimates is greatest in the transition zone (river mile 50 to 70) and is attributd to macrofaunal irrigation. Both in situ and diffusive fluxes of dissolved reactive phosphate from Potomac tidal river sediments are low while those from anoxic lower estuarine sediments are high. The net accumulation rate of phosphorus in benthic sediment exhibits an inverse pattern. Thus a large fraction of phosphorus is retained by Potomac tidal river sediments, which contain a surficial oxidized layer and oligochaete worms tolerant of low oxygen conditions, and a large fraction of phosphorus is released from anoxic lower estuary sediments. Tidal river sediment pore waters are in equilibrium with amorphous Fe (OH)3 while lower estuary pore waters are significantly undersaturated with respect to this phase. Benthic regeneration of dissolved reactive phosphorus is sufficient to supply all the phosphorus requirements for net primary production in the lower tidal river and transition-zone waters of the Potomac River Estuary. Benthic regeneration supplies approximately 25% as much phosphorus as inputs from sewage treatment plants and 10% of all phosphorus inputs to the tidal Potomac River. When all available point source phosphorus data are put into a steady-state conservation of mass model and reasonable coefficients for uptake of dissolved phosphorus, remineralization of particulate phosphorus, and sedimentation of particulate phosphorus are used in the model, a reasonably accurate simulation of dissolved and particulate phosphorus in the water column is obtained for the summer of 1980. ?? 1982 Dr W. Junk

  2. Velocity and bottom-stress measurements in the bottom boundary layer, outer Norton Sound, Alaska.

    USGS Publications Warehouse

    Cacchione, D.A.; Drake, D.E.; Wiberg, P.

    1982-01-01

    We have used long-term measurements of near-bottom velocities at four heights above the sea floor in Norton Sound, Alaska, to compute hourly values of shear velocity u., roughness and bottom-drag coefficient. Maximum sediment resuspension and transport, predicted for periods when the computed value of u. exceeds a critical level, occur during peak tidal currents associated with spring tides. The fortnightly variation in u. is correlated with a distinct nepheloid layer that intensifies and thickens during spring tides and diminishes and thins during neap tides. The passage of a storm near the end of the experiment caused significantly higher u. values than those found during fair weather.-from Authros

  3. Feasibility of remote sensing benthic microalgae

    NASA Technical Reports Server (NTRS)

    Zingmark, R. G.

    1979-01-01

    Results of data analyses from multispectral scanning data are presented. The data was collected in July 1977 for concentration of chlorophyll in benthic microalgae (mainly diatoms) on an estuary mudflat.

  4. EPA'S BENTHIC HABITAT DATA FOR YAQUINA ESTUARY

    EPA Science Inventory

    Scientists at EPA's National Health and Environmental Effects Research Laboratory, Western Ecology Division (WED) have been studying seafloor (benthic) habitats in Yaquina estuary for several years. Those studies were conducted as parts of several research projects, including: e...

  5. BENTHIC MACROFAUNAL ALIENS IN WILLAPA BAY

    EPA Science Inventory

    Benthic macrofaunal samples were collected at random stations in Willapa Bay, WA, in four habitats [eelgrass (Zostera marina), Atlantic cordgrass (Spartina alterniflora), mud shrimp (Upogebia pugettensis), ghost shrimp (Neotrypaea californiensis)] in 1996 and in seven habitats (Z...

  6. The benthic biological submodel in the European regional seas ecosystem model

    NASA Astrophysics Data System (ADS)

    Ebenhöh, W.; Kohlmeier, C.; Radford, P. J.

    The submodel describing benthic biology including a bioturbation module as incorporated in the European Regional Seas Ecosystem Model (ERSEM) is discussed. It is linked to a nutrient dynamic model. The structure of the benthic model food web is presented. There are four macrobenthic functional groups, meiobenthos and aerobic and anaerobic bacteria. The modelling uses 'standard organisms' as basic building blocks. The choice of parameter values is discussed. The results demonstrate the dependence of the benthic system on the pelagic system. The importance of features such as predation within functional groups for stability of the system is investigated. Detritus input from the pelagic system and detritus recycling is most important in the benthic food web. The web of carbon and nutrient fluxes through the system is analysed. On the basis of the food web analysis, the trophic positions of the functional groups are calculated. Besides the benthic biology, the mathematical formulation of the bioturbation and diffusion enhancement is discussed. Macrobenthic presence and activity enhance diffusion in the sediment and contribute essentially to vertical transport of particulate matter. This is of great importance for the vertical distribution of detritus, and as a consequence, for microbial activity in the sediment layers.

  7. Using Regional Distribution of Estuarine and Coastal Benthic Invertebrates to Calibrate Benthic Indices of Ecological Condition

    EPA Science Inventory

    The biogeography of marine benthic macroinvertebrates of the U.S. Atlantic coast from Delaware Bay north to Passamaquoddy Bay, Maine, was studied to define physical-chemical factors affecting broad taxa distributions and provide information needed to calibrate benthic indices of ...

  8. Carbon fate in a large temperate human-impacted river system: focus on benthic dynamics

    NASA Astrophysics Data System (ADS)

    Vilmin, Lauriane; Flipo, Nicolas; Escoffier, Nicolas; Rocher, Vincent; Groleau, Alexis

    2016-04-01

    During the last decade, several studies highlighted the important role of fluvial networks in regional and global carbon (C) budgets. Therefore, for sustainable C management, in-river C processing needs to be well understood. The Seine River from the Paris urban area to the entrance of its estuary (220 km) is studied here as a pertinent example of a large human impacted river system subject to temperate climatic conditions. We assess organic C (OC) budgets up- and downstream one of the world's largest waste water treatment plants and for different hydrological conditions through hydro-biogeochemical distributed modelling. The fine representation of sediment accumulation on the river bed allows the quantification of the effect of pelagic and benthic processes on OC export towards the estuary and on river metabolism (i.e. net CO2 emission). OC export is significantly affected by benthic dynamics during the driest periods, when 25 % of the inputs to the system is transformed or stored in the sediment layer. River metabolism is also significantly affected by benthic processes, whatever the hydrological conditions. On average, benthic respiration accounts for one third of the total ecosystem respiration along the studied stretch (0.23 out of 0.86 gC.m-2.d-1). These results stress the major influence of benthic dynamics, and thus of physical processes such as sedimentation and re-suspension on C cycling, in large human-impacted temperate river systems and on C export to the estuaries. Even though the importance of benthos processes was already acknowledged by the scientific community for headwater streams, this work highlights its importance for downstream river systems and opens the door to new developments in the quantification of C emissions by global models, in which biogeochemical processing and benthic dynamics must be taken into account.

  9. Cross-channel variability in benthic habitat

    USGS Publications Warehouse

    Vayssieres, Marc; Peterson, Heather

    2003-01-01

    The Interagency Ecological Program’s Environmental Monitoring Program (EMP) has monitored benthic invertebrates since the mid-1970s. A recent review of the EMP found that the spatial study design of the benthos monitoring element was in need of a thorough reexamination through intense special studies and extensive historic data analyses. This article reports the results of preliminary analyses of historical EMP data focusing on cross-channel variability. Specific questions are: (1) do benthic habitats and community assemblages vary between positions across a river channel? (2) Are benthic samples taken at a single channel position sufficiently representative of benthos assemblages across the channel to characterize long term changes in the benthos community of a particular section of a river?

  10. Estimates the Effects of Benthic Fluxes on the Water Quality of the Reservoir

    NASA Astrophysics Data System (ADS)

    Lee, H.; Huh, I. A.; Park, S.; Choi, J. H.

    2014-12-01

    Reservoirs located in highly populated and industrialized regions receive discharges of nutrients and pollutants from the watershed that have great potential to impair water quality and threaten aquatic life. The Euiam reservoir is a multiple-purpose water body used for tourism, fishery, and water supply and has been reported as eutrophic since 1990s. The external nutrients loading is considered to be the main cause of eutrophication of water bodies, and control strategies therefore focus on its reduction. However, algae blooms often continue even after external nutrients loading has been controlled, being benthic nutrient loading the main source of nutrients in the water column. Attempts to quantify benthic nutrients fluxes and their role as a source of nutrients to the water column have produced ambiguous results. Benthic flux is dependent on the upward flow of pore water caused by hydrostatic pressure, molecular diffusion, and mixing of sediment and water. In addition, it is controlled by dissolved oxygen (DO) levels, pH values and temperature in the overlying water. Therefore, linking a benthic flux to a water quality model should give us more insight on the effects of benthic fluxes to better quantify nutrient concentration within an entire reservoir system where physical, chemical, biological properties are variable. To represent temporal and spatial variations in the nutrient concentrations of the reservoir, a three-dimensional time variable model, Generalized Longitudinal-Lateral-Vertical Hydrodynamic and Transport (GLLVHT) was selected. The GLLVHT model is imbedded within the Generalized Environmental Modeling System for Surface waters (GEMSS). The computational grid of the three-dimensional model was developed using the GIS. The horizontal grid is composed of 580 active cells at the surface layer with spacing varies from 54.2 m to 69.8 m. There are 15 vertical layers with uniform thickness of 1.9 m resolution. To calibrate the model, model prediction for

  11. Long term cultivation of larger benthic Foraminifera

    NASA Astrophysics Data System (ADS)

    Wöger, Julia; Eder, Wolfgang; Kinoshita, Shunichi; Antonino, Briguglio; Carles, Ferrandes-Cañadell; Hohenegger, Johann

    2015-04-01

    Benthic Foraminifera are used in a variety of applications employing numerous different methods, i.e. ecological monitoring, studying the effects of ocean acidification, reconstructing palaeo-bathymetry or investigating palaeo-salinity and palaeo-temperature to name only a few. To refine our understanding of ecological influences on larger benthic foraminiferal biology and to review inferences from field observations, culture experiments have become an indispensable tool. While culture experiments on smaller benthic foraminifera have become increasingly frequent in the past century, reports of the cultivation of symbiont bearing larger Foraminifera are rare. Generally, cultivation experiments can be divided into two groups: Culturing of populations and cultivation of single specimens allowing individual investigation. The latter differ form the former by several restrictions resulting from the need to limit individual motility without abridging microenvironmental conditions in the Foraminiferans artificial habitat, necessary to enable the individual to development as unfettered as possible. In this study we present first experiences and preliminary results of the long-term cultivation of larger benthic Foraminifera conducted at the 'Tropical Biosphere Research Station Sesoko Island, University of the Ryukyus', Japan, trying to reproduce natural conditions as closely as possible. Individuals of three species of larger benthic Foraminifera (Heterostegina depressa, Palaeonummulites venosus and Operculina complanata) have been cultured since April 2014. At the time of the general assembly the cultivation experiments will have been going on for more than one year, with the aim to investigate growth rates, longevities and reproduction strategies for comparison with results statistically inferred from application of the of the 'natural laboratory' method. The most important factor influencing foraminiferal health and development was found to be light intensity and light

  12. Hadal disturbance in the Japan Trench induced by the 2011 Tohoku–Oki Earthquake

    PubMed Central

    Oguri, Kazumasa; Kawamura, Kiichiro; Sakaguchi, Arito; Toyofuku, Takashi; Kasaya, Takafumi; Murayama, Masafumi; Fujikura, Katsunori; Glud, Ronnie N.; Kitazato, Hiroshi

    2013-01-01

    In situ video observations and sediment core samplings were performed at two hadal sites in the Japan Trench on July, 2011, four months after the Tohoku–Oki earthquake. Video recordings documented dense nepheloid layers extending ~30–50 m above the sea bed. At the trench axis, benthic macrofauna was absent and dead organisms along with turbid downslope current were observed. The top 31 cm of sediment in the trench axis revealed three recent depositions events characterized by elevated 137Cs levels and alternating sediment densities. At 4.9 km seaward from the trench axis, little deposition was observed but the surface sediment contained 134Cs from the Fukushima Dai–ichi nuclear disaster. We argue that diatom blooms observed by remote sensing facilitated rapid deposition of 134Cs to hadal environment and the aftershocks induced successive sediment disturbances and maintained dense nepheloid layers in the trench even four months after the mainshock. PMID:23715086

  13. Time-response of cultured deep-sea benthic foraminifera to different algal diets

    NASA Astrophysics Data System (ADS)

    Heinz, P.; Hemleben, Ch; Kitazato, H.

    2002-03-01

    The vertical distribution of benthic foraminifera in the surface sediment is influenced by environmental factors, mainly by food and oxygen supply. An experiment of three different time series was performed to investigate the response of deep-sea benthic foraminifera to simulated phytodetritus pulses under stable oxygen concentrations. Each series was fed constantly with one distinct algal species in equivalent amounts. The temporal reactions of the benthic foraminifera with regard to the vertical distribution in the sediment, the total number, and the species composition were observed and compared within the three series. Additionally, oxygen contents and bacterial cell numbers were measured to ensure that these factors were invariable and did not influence foraminiferal communities. The addition of algae leads to higher population densities 21 days after food was added. Higher numbers of individuals were probably caused by higher organic levels, which in turn induced reproduction. A stronger response is found after feeding with Amphiprora sp. and Pyramimonas sp., compared to Dunaliella tertiolecta. At a constant high oxygen supply, no migration to upper layers was observed after food addition, and more individuals were found in deeper layers. The laboratory results thus agree with the predictions of the TROX-model. An epifaunal microhabitat preference was shown for Adercotryma glomerata. Hippocrepina sp. was spread over the entire sediment depth with a shallow infaunal maximum. Melonis barleeanum preferred a deeper infaunal habitat. Bacterial cell concentrations were stable during the laboratory experiments and showed no significant response to higher organic fluxes.

  14. Relationship between the location of chemosynthetic benthic communities and geologic structure on the Cascadia subduction zone

    SciTech Connect

    Lewis, B.T.R. ); Cochrane, G.C. )

    1990-06-10

    Chemosynthetic benthic communities, which live symbiotically with microbes capable of metabolizing nutrients dissolved in water seeping out of the seafloor, are widespread along the Cascadia subduction zone. These seeps and vents are therefore indicative of one mode of fluid migration out of the subduction zone sediments. The authors have used deep-towed seismic methods, including hydrophones mounted on Alvin, to examine the detailed geologic structure under two of these vent sites. At one of the sites, located on a seaward dipping thrust zone, the benthic communities are associated with a disruption of the subsurface acoustic layering in the thrust zone. It appears that at this site, dewatering is occurring along fractures in the disrupted sediments which connect to permeable layers in the undeformed sediments and not along the main thrust fault. The other site is located near the top of a ridge which has been uplifted by thrusting along a landward dipping thrust. Most of the benthic communities are found to exist at the outcrop of a steeply dipping unconformity between recent slope-basin sediments and the older uplifted sediments, with the unconformity serving as the fluid pathway. Underlying this unconformity at the most active dewatering location is a complexly deformed structure which appears to enhance the flow of fluid to the unconformity. The source of the fluids could be the older uplifted sediments or the recent slope-basin turbidites. In either case the source is shallow, less than about 1 km.

  15. Harnessing the self-harvesting capability of benthic cyanobacteria for use in benthic photobioreactors

    PubMed Central

    2011-01-01

    Benthic species of algae and cyanobacteria (i.e., those that grow on surfaces), may provide potential advantages over planktonic species for some commercial-scale biotechnological applications. A multitude of different designs of photobioreactor (PBR) are available for growing planktonic species but to date there has been little research on PBR for benthic algae or cyanobacteria. One notable advantage of some benthic cyanobacterial species is that during their growth cycle they become positively buoyant, detach from the growth surface and form floating mats. This 'self-harvesting' capability could be advantageous in commercial PBRs as it would greatly reduce dewatering costs. In this study we compared the growth rates and efficiency of 'self-harvesting' among three species of benthic cyanobacteria; Phormidium autumnale; Phormidium murrayi and Planktothrix sp.. Phormidium autumnale produced the greatest biomass and formed cohesive mats once detached. Using this strain and an optimised MLA media, a variety of geometries of benthic PBRs (bPBRs) were trialed. The geometry and composition of growth surface had a marked effect on cyanobacterial growth. The highest biomass was achieved in a bPBR comprising of a vertical polyethylene bag with loops of silicone tubing to provide additional growth surfaces. The productivity achieved in this bPBR was a similar order of magnitude as planktonic species, with the additional advantage that towards the end of the exponential phase the bulk of the biomass detached forming a dense mat at the surface of the medium. PMID:21906375

  16. Assessing benthic community condition in Chesapeake Bay: does the use of different benthic indices matter?

    PubMed

    Llansó, Roberto J; Vølstad, Jon H; Dauer, Daniel M; Dew, Jodi R

    2009-03-01

    Federal and state environmental agencies conduct several programs to characterize the environmental condition of Chesapeake Bay. These programs use different benthic indices and survey designs, and have produced assessments that differ in the estimate of the extent of benthic community degradation in Chesapeake Bay. Provided that the survey designs are unbiased, differences may exist in the ability of these indices to identify environmental degradation. In this study we compared the results of three indices calculated on the same data, and the assessments of two programs: the Chesapeake Bay Program and the Mid-Atlantic Integrated Assessment (MAIA). We examined the level of agreement of index results using site-based measures of agreement, evaluated sampling designs and statistical estimation methods, and tested for significant differences in assessments. Comparison of ratings of individual sites was done within separate categories of water and sediment quality to identify which indices summarize best pollution problems in Chesapeake Bay. The use of different benthic indices by these programs produced assessments that differed significantly in the estimate of degradation. A larger fraction of poor sites was classified as good by the Environmental Monitoring and Assessment Program's Virginian Province and MAIA benthic indices compared to the Chesapeake Bay benthic index of biotic integrity, although overall classification efficiencies were similar for all indices. Differences in survey design also contributed to differences in assessments. The relative difference between the indices remained the same when they were applied to an independent dataset, suggesting that the indices can be calibrated to produce consistent results.

  17. Benthic habitat mapping using hyperspectral remote sensing

    NASA Astrophysics Data System (ADS)

    Vélez-Reyes, Miguel; Goodman, James A.; Castrodad-Carrau, Alexey; Jiménez-Rodriguez, Luis O.; Hunt, Shawn D.; Armstrong, Roy

    2006-09-01

    Benthic habitats are the different bottom environments as defined by distinct physical, geochemical, and biological characteristics. Remote sensing is increasingly being used to map and monitor the complex dynamics associated with estuarine and nearshore benthic habitats. Advantages of remote sensing technology include both the qualitative benefits derived from a visual overview, and more importantly, the quantitative abilities for systematic assessment and monitoring. Advancements in instrument capabilities and analysis methods are continuing to expand the accuracy and level of effectiveness of the resulting data products. Hyperspectral sensors in particular are rapidly emerging as a more complete solution, especially for the analysis of subsurface shallow aquatic systems. The spectral detail offered by hyperspectral instruments facilitates significant improvements in the capacity to differentiate and classify benthic habitats. This paper reviews two techniques for mapping shallow coastal ecosystems that both combine the retrieval of water optical properties with a linear unmixing model to obtain classifications of the seafloor. Example output using AVIRIS hyperspectral imagery of Kaneohe Bay, Hawaii is employed to demonstrate the application potential of the two approaches and compare their respective results.

  18. THE BENTHIC COMMUNITIES COMPARISON BETWEEN ORGANIC AND CONVENTIONAL RICE FIELDS.

    PubMed

    Kasamesiri, P; Thaimuangphol, W

    2015-01-01

    Rice fields are temporary wetlands prone to contamination from agricultural chemicals which affect their ecotoxicology and benthic community composition. The diversity of benthic fauna in both organic and conventional rice fields in Kalasin Province, Thailand was investigated. Benthos samples were collected by grab sampling from 20 stations in organic and conventional rice fields during one successive crop in August 2014. The number of benthic organisms found at each sampling station ranged from 16-518 and 24-137 individuals for organic and conventional rice fields, respectively. The benthic fauna in organic rice fields were dominated by crustaceans 41%, insects 31%, annelids 26%, and gastropods 2%. The conventional rice fields benthic fauna was composed of insects 51%, annelids 41%, and gastropods 8%. The abundance and composition of the benthic fauna demonstrated that organic rice farming practices are beneficial to sustaining the biodiversity in rice field ecosystems.

  19. State of the benthic ecosystem on western Black Sea shelf in spring 2008

    NASA Astrophysics Data System (ADS)

    Friedrich, J.; Aleynik, D.; Eulenburg, A.; Kusch, St.; Mee, L. D.; Minicheva, G.; Stevens, T. F.; Teaca, A.; Shapiro, G. I.; Soloviev, D.

    2009-04-01

    : thermal heating and freshwater input created a double front structure on the western shelf, and intrusion of the Cold Intermediate Layer (CIL) into shelf waters was observed. Surface distribution of dissolved nutrients reflects clear signals of silica and total dissolved nitrogen input from the Danube River. Phosphate appears to have a different source, e.g. benthic and/or from the CIL. The benthic ecosystem remains fragile; diversity indices reflect small recovery, quantities in biomass of both zoo- and phytobenthos indicate ongoing perturbations in nearshore areas. A full recovery of historical beds of Phyllophora is not evident, coverage both in winter and summer is less than 10%, and its role as habitat could be compromised by overgrowth of filamentous algae. The benthic system with an epibenthic community in balance releases less nutrients than a disturbed system without benthic life. Nutrients release from the sediment is lower in winter than in summer. The oxygen penetration depth in the sediment triggers denitrification. A spectacular population development of opportunistic species both in zoo- and phytobenthos was observed. The question remains whether or not those opportunistic species can ensure ecosystem functionality and stability. Our findings will help to identify locations crucial for the functioning for the benthic shelf ecosystem, to define "Good Environmental Status" and help to provide recommendations for Marine protected areas on the western Black Sea shelf. It is hoped that the data will make an important contribution to the information base underpinning the new European Marine Strategy Directive and the Bucharest Convention for the Protection of the Black Sea.

  20. Benthic Macroinvertebrate Assemblages and Environmental Correlates in Springs of the Ridge and Valley Province

    EPA Science Inventory

    Springs are unique features in the landscape that provide important habitat for benthic invertebrates, yet there are few studies characterizing the distribution of benthic macro invertebrates in springs. Benthic macroinvertebrate and water quality data were collected at 35 spring...

  1. Diachronous benthic δ18O responses during late Pleistocene terminations

    NASA Astrophysics Data System (ADS)

    Lisiecki, Lorraine E.; Raymo, Maureen E.

    2009-09-01

    Benthic δ18O is often used as a stratigraphic tool to place marine records on a common age model and as a proxy for the timing of ice volume/sea level change. However, Skinner and Shackleton (2005) found that the timing of benthic δ18O change at the last termination differed by 3900 years between one Atlantic site and one Pacific site. These results suggest that benthic δ18O change may not always accurately record the timing of deglaciation. We compare benthic δ18O records from 20 Atlantic sites and 14 Pacific sites to evaluate systematic differences in the timing of terminations in benthic δ18O. Analysis of sedimentation rates derived from the alignment of benthic δ18O suggests a statistically significant Atlantic lead over Pacific benthic δ18O change during the last six terminations. We estimate an average Pacific benthic δ18O lag of 1600 years for Terminations 1-5, slightly larger than the delay expected from ocean mixing rates given that most glacial meltwater probably enters the North Atlantic. We additionally find evidence of ˜4000-year Pacific δ18O lags at approximately 128 ka and 330 ka, suggesting that stratigraphic correlation of δ18O has the potential to generate age model errors of several thousand years during terminations. A simple model demonstrates that these lags can be generated by diachronous temperature changes and do not require slower circulation rates. Most importantly, diachronous benthic δ18O responses must be taken into account when comparing Atlantic and Pacific benthic δ18O records or when using benthic δ18O records as a proxy for the timing of ice volume change.

  2. Benthic fluxes in San Francisco Bay

    USGS Publications Warehouse

    Hammond, Douglas E.; Fuller, C.; Harmon, D.; Hartman, Blayne; Korosec, M.; Miller, L.G.; Rea, R.; Warren, S.; Berelson, W.; Hager, S.W.

    1985-01-01

    Measurements of benthic fluxes have been made on four occasions between February 1980 and February 1981 at a channel station and a shoal station in South San Francisco Bay, using in situ flux chambers. On each occasion replicate measurements of easily measured substances such as radon, oxygen, ammonia, and silica showed a variability (??1??) of 30% or more over distances of a few meters to tens of meters, presumably due to spatial heterogeneity in the benthic community. Fluxes of radon were greater at the shoal station than at the channel station because of greater macrofaunal irrigation at the former, but showed little seasonal variability at either station. At both stations fluxes of oxygen, carbon dioxide, ammonia, and silica were largest following the spring bloom. Fluxes measured during different seasons ranged over factors of 2-3, 3, 4-5, and 3-10 (respectively), due to variations in phytoplankton productivity and temperature. Fluxes of oxygen and carbon dioxide were greater at the shoal station than at the channel station because the net phytoplankton productivity is greater there and the organic matter produced must be rapidly incorporated in the sediment column. Fluxes of silica were greater at the shoal station, probably because of the greater irrigation rates there. N + N (nitrate + nitrite) fluxes were variable in magnitude and in sign. Phosphate fluxes were too small to measure accurately. Alkalinity fluxes were similar at the two stations and are attributed primarily to carbonate dissolution at the shoal station and to sulfate reduction at the channel station. The estimated average fluxes into South Bay, based on results from these two stations over the course of a year, are (in mmol m-2 d-1): O2 = -27 ?? 6; TCO2 = 23 ?? 6; Alkalinity = 9 ?? 2; N + N = -0.3 ?? 0.5; NH3 = 1.4 ?? 0.2; PO4 = 0.1 ?? 0.4; Si = 5.6 ?? 1.1. These fluxes are comparable in magnitude to those in other temperate estuaries with similar productivity, although the seasonal

  3. Use of a novel sediment exposure to determine the effects of triclosan on estuarine benthic communities.

    PubMed

    Ho, Kay T; Chariton, Anthony A; Portis, Lisa M; Proestou, Dina; Cantwell, Mark G; Baguley, Jeffrey G; Burgess, Robert M; Simpson, Stuart; Pelletier, Marguerite C; Perron, Monique M; Gunsch, Claudia K; Bik, Holly M; Katz, David; Kamikawa, Anthony

    2013-02-01

    Triclosan (5-chloro-2-[2,4-dichlorophenoxy]phenol) is a relatively new, commonly used antimicrobial compound found in many personal care products. Triclosan is toxic to marine organisms at the micrograms per liter level, can photodegrade to a dioxin, can accumulate in humans, and has been found to be stable in marine sediments for over 30 years. To determine the effects of triclosan on marine benthic communities, intact sediment cores were brought into the laboratory and held under flowing seawater conditions. A 2-cm layer of triclosan-spiked sediment was applied to the surface, and after a two-week exposure the meio- and macrofaunal communities were assessed for differences in composition relative to nonspiked cores. A high triclosan treatment (180 mg/kg dry wt) affected both the meio- and the macrobenthic communities. There were no discernible differences with a low-triclosan treatment (14 mg/kg dry wt). This exposure method is effective for testing the benthic community response to sediment contaminants, but improvements should be made with regard to the amount and method of applying the overlying sediment to prevent smothering of fragile benthic organisms.

  4. A MORE COST-EFFECTIVE EMAP BENTHIC MACROFAUNAL SAMPLING PROTOCOL

    EPA Science Inventory

    Benthic macrofaunal sampling protocols in the U.S. Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) are to collect 30 to 50 random benthic macrofauna [defined as animals retained on a 0.5 mm (East and Gulf Coasts, USA) or a 1.0 mm mesh siev...

  5. BENTHIC NUTRIENT FLUX IN A SMALL ESTUARY IN NORTHWESTERNFLORIDA (USA)

    EPA Science Inventory

    Benthic Nutrient Flux in a Small Estuary in Northwestern Florida(USA).Gulf and Caribbean Research 18, 15-25, 2006.

    Benthic nutrient fluxes of ammonium (NH4+), nitrite/nitrate (NO2-+NO3-), phosphate (PO4-), and dissolved silica (DSi) were measured in Escambia Bay, an estuar...

  6. LATITUDINAL GRADIENTS IN BENTHIC COMMUNITY COMPOSITION IN WESTERN ATLANTIC ESTUARIES

    EPA Science Inventory

    The community structure of benthic macroinvertebrates from estuaries along the Atlantic coast of North America from Cape Cod, MA, to Biscayne Bay, FL, were compared. Benthic data were collected over a 5 year period (1990 to 1995) by the U.S. Environmental Protection Agency's Envi...

  7. Generalized analytical model for benthic water flux forced by surface gravity waves

    USGS Publications Warehouse

    King, J.N.; Mehta, A.J.; Dean, R.G.

    2009-01-01

    A generalized analytical model for benthic water flux forced by linear surface gravity waves over a series of layered hydrogeologic units is developed by adapting a previous solution for a hydrogeologic unit with an infinite thickness (Case I) to a unit with a finite thickness (Case II) and to a dual-unit system (Case III). The model compares favorably with laboratory observations. The amplitude of wave-forced benthic water flux is shown to be directly proportional to the amplitude of the wave, the permeability of the hydrogeologic unit, and the wave number and inversely proportional to the kinematic viscosity of water. A dimensionless amplitude parameter is introduced and shown to reach a maximum where the product of water depth and the wave number is 1.2. Submarine groundwater discharge (SGD) is a benthic water discharge flux to a marine water body. The Case I model estimates an 11.5-cm/d SGD forced by a wave with a 1 s period and 5-cm amplitude in water that is 0.5-m deep. As this wave propagates into a region with a 0.3-m-thick hydrogeologic unit, with a no-flow bottom boundary, the Case II model estimates a 9.7-cm/d wave-forced SGD. As this wave propagates into a region with a 0.2-m-thick hydrogeologic unit over an infinitely thick, more permeable unit, the Case III quasi-confined model estimates a 15.7-cm/d wave-forced SGD. The quasi-confined model has benthic constituent flux implications in coral reef, karst, and clastic regions. Waves may undermine tracer and seepage meter estimates of SGD at some locations. Copyright 2009 by the American Geophysical Union.

  8. Benthic processes affecting contaminant transport in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Kuwabara, James S.; Topping, Brent R.; Carter, James L.; Carlson, Rick A; Parchaso, Francis; Fend, Steven V.; Stauffer-Olsen, Natalie; Manning, Andrew J.; Land, Jennie M.

    2016-09-30

    Executive SummaryMultiple sampling trips during calendar years 2013 through 2015 were coordinated to provide measurements of interdependent benthic processes that potentially affect contaminant transport in Upper Klamath Lake (UKL), Oregon. The measurements were motivated by recognition that such internal processes (for example, solute benthic flux, bioturbation and solute efflux by benthic invertebrates, and physical groundwater-surface water interactions) were not integrated into existing management models for UKL. Up until 2013, all of the benthic-flux studies generally had been limited spatially to a number of sites in the northern part of UKL and limited temporally to 2–3 samplings per year. All of the benthic invertebrate studies also had been limited to the northern part of the lake; however, intensive temporal (weekly) studies had previously been completed independent of benthic-flux studies. Therefore, knowledge of both the spatial and temporal variability in benthic flux and benthic invertebrate distributions for the entire lake was lacking. To address these limitations, we completed a lakewide spatial study during 2013 and a coordinated temporal study with weekly sampling of benthic flux and benthic invertebrates during 2014. Field design of the spatially focused study in 2013 involved 21 sites sampled three times as the summer cyanobacterial bloom developed (that is, May 23, June 13, and July 3, 2013). Results of the 27-week, temporally focused study of one site in 2014 were summarized and partitioned into three periods (referred to herein as pre-bloom, bloom and post-bloom periods), each period involving 9 weeks of profiler deployments, water column and benthic sampling. Partitioning of the pre-bloom, bloom, and post-bloom periods were based on water-column chlorophyll concentrations and involved the following date intervals, respectively: April 15 through June 10, June 17 through August 13, and August 20 through October 16, 2014. To examine

  9. New Benthic δ18o Stacks and Age Models for the Last Glacial Cycle (0-150 kyr ago)

    NASA Astrophysics Data System (ADS)

    Lisiecki, L. E.; Stern, J. V.

    2014-12-01

    The δ18O of formainiferal calcite is a common paleoceanographic proxy, which measures ice volume and deep water temperature change. Foraminiferal δ18O is also often used to create marine sediment core age models by aligning down-core variations in δ18O to a global stack, or average. However, the most commonly used stack, known as "LR04," has an outdated age model, assumes global benthic δ18O synchrony, and is biased to the Atlantic [Lisiecki and Raymo, 2005]. Here we present six regional benthic δ18O stacks of the last glacial cycle (0-150 kyr) that are combined to form a volume-weighted global stack with data from 263 sites. We develop new benthic δ18O age models using regional radiocarbon dates from 0-40 ka and correlations to the GICC05 layer-counted Greenland age model from 40-56 ka [Svensson et al., 2008] and U-Th-dated Chinese speleothems from 56-150 kyr [Wang et al., 2001; Cheng et al., 2009; Barker et al, 2011]. Additional features of the new stacks are diachronous benthic δ18O changes during the last two glacial terminations and explicit age uncertainty estimates throughout. Our new global stack indicates that some portions of the LR04 stack are up to 4 kyr too young. We estimate corrections to the LR04 age model throughout the Pleistocene that imply faster climate responses to orbital forcing than previously estimated.

  10. Diel Variability in Seawater pH Relates to Calcification and Benthic Community Structure on Coral Reefs

    PubMed Central

    Martz, Todd R.; Brainard, Russell E.

    2012-01-01

    Community structure and assembly are determined in part by environmental heterogeneity. While reef-building corals respond negatively to warming (i.e. bleaching events) and ocean acidification (OA), the extent of present-day natural variability in pH on shallow reefs and ecological consequences for benthic assemblages is unknown. We documented high resolution temporal patterns in temperature and pH from three reefs in the central Pacific and examined how these data relate to community development and net accretion rates of early successional benthic organisms. These reefs experienced substantial diel fluctuations in temperature (0.78°C) and pH (>0.2) similar to the magnitude of ‘warming’ and ‘acidification’ expected over the next century. Where daily pH within the benthic boundary layer failed to exceed pelagic climatological seasonal lows, net accretion was slower and fleshy, non-calcifying benthic organisms dominated space. Thus, key aspects of coral reef ecosystem structure and function are presently related to natural diurnal variability in pH. PMID:22952785

  11. Assessment of Arctic community wastewater impacts on marine benthic invertebrates.

    PubMed

    Krumhansl, Kira A; Krkosek, Wendy H; Greenwood, Mark; Ragush, Colin; Schmidt, Jordan; Grant, Jon; Barrell, Jeff; Lu, Lin; Lam, Buuan; Gagnon, Graham A; Jamieson, Rob C

    2015-01-20

    This study sought to understand the performance of arctic treatment systems and the impact of wastewater effluent on benthic invertebrate communities in arctic receiving water habitats. Effluent quality and benthic impacts were monitored in the receiving water of five communities across Nunavut that differed in the type and level of treatment achieved by wastewater infrastructure, the volume of effluent and receiving water mixing environment. We detected minimal impacts to benthic communities (<225 m linear distance from the effluent source) in four out of the five communities (Grise Fiord, Kugaaruk, Pond Inlet, and Pangnirtung), where the population was <2000 people. In these small communities impacts were characterized by increases or decreases in species richness, diversity, evenness, and density, and some differences in benthic species composition. This was in contrast to benthic sediments in Iqaluit (population 6699), which were devoid of benthic fauna up to 580 m from the effluent source in response to sediment anoxia. Variation in benthic community response between sampling locations was attributed primarily to differences in effluent volume, with effluent quality and receiving water hydrodynamics playing secondary roles. The results of this study will help to inform the development of northern specific treatment performance standards which will aid in prioritizing community wastewater system upgrades in arctic communities.

  12. Preliminary results from a shallow water benthic grazing study

    USGS Publications Warehouse

    Jones, N.L.; Monismith, Stephen G.; Thompson, Janet K.

    2005-01-01

    Despite great improvements in our knowledge on the effects of benthic grazers on seston concentrations in water columns, the effects of different hydrodynamic conditions on grazing rates has not been formulated. This makes it difficult to assess the system-wide effect of the benthic ecosystem on phytoplankton concentrations. Furthermore, it affects our ability to predict the potential success of a benthic species, such as the invasive clams Corbicula fluminea and Potamocorbula amurensis. This paper presents the preliminary results of a control volume approach to elucidate the effect of different hydrodynamic conditions on the grazing rates of Corbicula fluminea.

  13. Post-depositional alteration of benthic foraminifera in a methane seep environment

    NASA Astrophysics Data System (ADS)

    Schneider, Andrea; Cremiere, Antoine; Panieri, Giuliana; Lepland, Aivo; Knies, Jochen

    2016-04-01

    Benthic foraminifera tests from the sediment cores taken from the Vestnesa Ridge, one of the northernmost known marine methane hydrate reservoir, were studied for their visual appearance, mineral and stable carbon isotopic composition in order to explore their indicator potential in a methane seep environment. The Vestnesa Ridge is a sediment drift located in 1200m water depth at 79°N at Svalbard's northwestern continental margin. Observations of gas flares originating from pockmarks that are aligned along the crest of the ridge show ongoing methane emission. A distinct sediment layer containing a fossilized assemblage of chemosynthetic bivalves indicates methane seepage activity at least in the late Pleistocene. We have examined the state of preservation and geochemical characteristics of foraminifera tests from this bivalve shell horizon. Tests of the benthic foraminifera species Cassidulina neoteretis display a variable degree of post-depositional alteration and formation of diagenetic carbonate overgrowths on calcitic primary tests. Using binoculars, scanning electron microscope imagery and energy dispersive x-ray spectroscopy, we distinguish visually and mineralogically different diagenetic phases on the external and internal test surfaces. Pristine and smooth test surfaces act as nucleation templates for precipitation of authigenic Mg-calcite crystals causing complete filling of chambers and encrustation of the external test surfaces. The presence of Mg-calcite indicates the overgrowth is precipitating in sulfate-poor sediments. In addition to benthic foraminifera, we have studied the mineralogical and stable carbon and oxygen isotope composition of authigenic carbonate nodules found in the bivalve shell horizon. The mineralogical nature of the carbonates and overgrowths on the foraminifera tests were found to be identical. The δ13C value of the carbonate nodules is as low as -32.3‰ indicating their methane-derived origin. Authigenic carbonate coated

  14. WASP7 BENTHIC ALGAE - MODEL THEORY AND USER'S GUIDE

    EPA Science Inventory

    The standard WASP7 eutrophication module includes nitrogen and phosphorus cycling, dissolved oxygen-organic matter interactions, and phytoplankton kinetics. In many shallow streams and rivers, however, the attached algae (benthic algae, or periphyton, attached to submerged substr...

  15. BENTHIC MACROFAUNA-HABITAT RELATIONSHIPS IN WILLAPA BAY, WA

    EPA Science Inventory

    Benthic macrofauna-habitat relationships were determined estuary-wide in Willapa Bay, WA for four intertidal habitats ((1) eelgrass, Zostera marina, (2) Atlantic cordgrass, Spartina alterniflora, (3) ghost shrimp, Neotrypaea californiensis, (4) mud shrimp, Upogebia pugettensis) i...

  16. BENTHIC MACROFAUNA-HABITAT ASSOCIATIONS IN WILLAPA BAY, WASHINGTON, USA

    EPA Science Inventory

    Estuary-wide benthic macrofauna-habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [Zostera marina], Atlantic cordgrass [Spartina alterniflora], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis]) in 1...

  17. SAMPLING LARGE RIVERS FOR ALGAE, BENTHIC MACROINVERTEBRATES AND FISH

    EPA Science Inventory

    Multiple projects are currently underway to increase our understanding of the effects of different sampling methods and designs used for the biological assessment and monitoring of large (boatable) rivers. Studies include methods used to assess fish, benthic macroinvertebrates, ...

  18. DECLINE IN LAKE ONTARIO POPULATIONS OF BENTHIC MACROINVERTEBRATES

    EPA Science Inventory

    Surveys of benthic macroinvertebrates conducted in Lake Ontario during 1994 and 1997 revealed declines in populations of three major groups of organisms: oligochaetes, sphariids, and Diporeia spp. (Amphipoda), with the most drastic reductions occurring in the latter. Based on phy...

  19. Influence of sea squirt (Halocynthia roretzi) aquaculture on benthic-pelagic coupling in coastal waters: A study of the South Sea in Korea

    NASA Astrophysics Data System (ADS)

    Lee, Jae Seong; Kim, Sung-Han; Kim, Yong-Tae; Hong, Sok Jin; Han, Jeong Hee; Hyun, Jung-Ho; Shin, Kyung-Hoon

    2012-03-01

    The influence of sea squirt aquaculture on benthic-pelagic coupling was evaluated in semi-enclosed Korean coastal waters with an in situ benthic chamber and results show for the first time that suspended sea squirt cultures play an important role in benthic-pelagic coupling in the coastal zone. Measurements of primary production, vertical particulate fluxes, and benthic fluxes were made at two stations, a sea squirt (Halocynthia roretzi) farm (SSF) and an area of organic-matter-enriched sediment in Jinhae Bay. The vertical material fluxes of organic carbon, nitrogen, and biogenic silicate (BSi) were significantly higher at SSF than in Jinhae Bay, indicating massive biodeposits in the surface sediments at SSF. The organic carbon oxidation rates (Cox) were estimated after correction for CaCO3 dissolution. The average Cox at SSF (204 mmol C m-2 d-1) was significantly higher than that in the organic-enriched Jinhae Bay sediment (77 mmol C m-2 d-1). The organic carbon burial fluxes were determined using vertical profiles of organic carbon of up to 30 cm and the sedimentation rate calculated from the excess 210Pb distribution. At both stations, ˜95% of the settled organic carbon was oxidized and only ˜5% was buried in the deep sediment layer. The benthic fluxes of dissolved inorganic nitrogen and phosphate at SSF were 2-12 times higher than in Jinhae Bay, corresponding to 85%, and 270%, respectively, of the requirements for primary production.

  20. Modelling benthic biophysical drivers of ecosystem structure and biogeochemical response

    NASA Astrophysics Data System (ADS)

    Stephens, Nicholas; Bruggeman, Jorn; Lessin, Gennadi; Allen, Icarus

    2016-04-01

    The fate of carbon deposited at the sea floor is ultimately decided by biophysical drivers that control the efficiency of remineralisation and timescale of carbon burial in sediments. Specifically, these drivers include bioturbation through ingestion and movement, burrow-flushing and sediment reworking, which enhance vertical particulate transport and solute diffusion. Unfortunately, these processes are rarely satisfactorily resolved in models. To address this, a benthic model that explicitly describes the vertical position of biology (e.g., habitats) and biogeochemical processes is presented that includes biological functionality and biogeochemical response capturing changes in ecosystem structure, benthic-pelagic fluxes and biodiversity on inter-annual timescales. This is demonstrated by the model's ability to reproduce temporal variability in benthic infauna, vertical pore water nutrients and pelagic-benthic solute fluxes compared to in-situ data. A key advance is the replacement of bulk parameterisation of bioturbation by explicit description of the bio-physical processes responsible. This permits direct comparison with observations and determination of key parameters in experiments. Crucially, the model resolves the two-way interaction between sediment biogeochemistry and ecology, allowing exploration of the benthic response to changing environmental conditions, the importance of infaunal functional traits in shaping benthic ecological structure and the feedback the resulting bio-physical processes exert on pore water nutrient profiles. The model is actively being used to understand shelf sea carbon cycling, the response of the benthos to climatic change, food provision and other societal benefits.

  1. Partially repeatable genetic basis of benthic adaptation in threespine sticklebacks.

    PubMed

    Erickson, Priscilla A; Glazer, Andrew M; Killingbeck, Emily E; Agoglia, Rachel M; Baek, Jiyeon; Carsanaro, Sara M; Lee, Anthony M; Cleves, Phillip A; Schluter, Dolph; Miller, Craig T

    2016-04-01

    The extent to which convergent adaptation to similar ecological niches occurs by a predictable genetic basis remains a fundamental question in biology. Threespine stickleback fish have undergone an adaptive radiation in which ancestral oceanic populations repeatedly colonized and adapted to freshwater habitats. In multiple lakes in British Columbia, two different freshwater ecotypes have evolved: a deep-bodied benthic form adapted to forage near the lake substrate, and a narrow-bodied limnetic form adapted to forage in open water. Here, we use genome-wide linkage mapping in marine × benthic F2 genetic crosses to test the extent of shared genomic regions underlying benthic adaptation in three benthic populations. We identify at least 100 Quantitative Trait Loci (QTL) harboring genes influencing skeletal morphology. The majority of QTL (57%) are unique to one cross. However, four genomic regions affecting eight craniofacial and armor phenotypes are found in all three benthic populations. We find that QTL are clustered in the genome and overlapping QTL regions are enriched for genomic signatures of natural selection. These findings suggest that benthic adaptation has occurred via both parallel and nonparallel genetic changes. PMID:26947264

  2. Lake Malawi cichlid evolution along a benthic/limnetic axis

    PubMed Central

    Hulsey, C D; Roberts, R J; Loh, Y-H E; Rupp, M F; Streelman, J T

    2013-01-01

    Divergence along a benthic to limnetic habitat axis is ubiquitous in aquatic systems. However, this type of habitat divergence has largely been examined in low diversity, high latitude lake systems. In this study, we examined the importance of benthic and limnetic divergence within the incredibly species-rich radiation of Lake Malawi cichlid fishes. Using novel phylogenetic reconstructions, we provided a series of hypotheses regarding the evolutionary relationships among 24 benthic and limnetic species that suggests divergence along this axis has occurred multiple times within Lake Malawi cichlids. Because pectoral fin morphology is often associated with divergence along this habitat axis in other fish groups, we investigated divergence in pectoral fin muscles in these benthic and limnetic cichlid species. We showed that the eight pectoral fin muscles and fin area generally tended to evolve in a tightly correlated manner in the Lake Malawi cichlids. Additionally, we found that larger pectoral fin muscles are strongly associated with the independent evolution of the benthic feeding habit across this group of fish. Evolutionary specialization along a benthic/limnetic axis has occurred multiple times within this tropical lake radiation and has produced repeated convergent matching between exploitation of water column habitats and locomotory morphology. PMID:23919168

  3. Parameterisation of clastic sediments including benthic structures

    NASA Astrophysics Data System (ADS)

    Bobertz, B.; Harff, J.; Bohling, B.

    2009-02-01

    The sediment transport processes in the south-western Baltic Sea are predicted by means of a numerical model in the project DYNAS. There are two sediment parameters that influence the results of modelling remarkably: critical shear stress velocity and bottom roughness. This paper presents the way how to parameterise these factors and extrapolate them into the investigation area. The critical shear stress velocity is parameterised basing on grain size data, combining approximations after Hjulström [Hjulström, F., 1935: Studies in the morphological activity of rivers as illustrated by the river Fyris. Geological Institution of University of Uppsala: Bulletin (25): 221-528.], Shields [Shields, A., 1936: Anwendung der Ähnlichkeits-Mechanik und der Turbulenzforschung auf die Geschiebebewegung. Mitteilungen der Preussischen Versuchsanstalt für Wasserbau und Schiffahrt (26): 26 pp.] and Bohling [Bohling, B., 2003: Untersuchungen zur Mobilität natürlicher und anthropogener Sedimente in der Mecklenburger Bucht. unpublished doctoral thesis, Mathematisch-Naturwissenschaftliche Fakultät, Ernst-Moritz-Arndt-Universität Greifswald/Germany, 156 pp.]. The roughness length, in the case of absence of macro zoo-benthos and their structures, is parameterised basing on grain size too employing Soulsby [Soulsby, R.L., 1997: Dynamics of Marine Sands: a Manual for Practical Applications. London, Thomas Telford Publications. 249 pp.], Nielsen [Nielsen, P., 1983: Analytical determination of nearshore wave height variation due to refraction shoaling and friction. Coastal Engineering 7, 233-251.] and Yalin [Yalin, M.S., 1977: Mechanics of Sediment Transport. Pergamon Press, New York. 298 pp.]. No equivalent simple parameterisations for biologically caused bed roughness exist. Here, findings of Friedrichs [Friedrichs, M., 2004: Flow-induced effects of macro zoo-benthic structures on the near-bed sediment transport. Dissertation, Universität Rostock, 80 S.] and estimations by the DYNAS

  4. Miocene benthic foraminiferal isotope records: A synthesis

    USGS Publications Warehouse

    Savin, S.M.; Douglas, R.G.; Keller, G.; Killingley, J.S.; Shaughnessy, L.; Sommer, M.A.; Vincent, E.; Woodruff, F.

    1981-01-01

    18O 16O and 13C 12C ratios of Miocene benthic foraminifera from a number of Atlantic, Pacific and Indian Ocean DSDP sites (71, 77B, 206, 208, 238, 279, 289, 296, 329, 357 and 366A) have been compiled. These provide a rather detailed history of Miocene deep water especially in the Pacific Ocean. Bottom-water temperatures rose during the early Miocene and then declined rapidly during the middle Miocene. This decline was accompanied by an increase in Antarctic glaciation. Late Miocene bottom temperatures and Antarctic ice volumes are inferred to be similar to today's, but exhibited some fluctuation. The early Miocene ocean was less thermally stratified at intermediate and abyssal depths while the late Miocene deep ocean had a thermal structure generally similar to the modern ocean. Foraminiferal carbon isotope ratios at most of the sites varied quasi-sympathetically throughout the Miocene. These variations must reflect comparable variations in the mean 13C 12C of marine HCO3-. However, the causes of such variations are not yet clear. ?? 1981.

  5. Hydrothermal exploration with the Autonomous Benthic Explorer

    NASA Astrophysics Data System (ADS)

    German, Christopher R.; Yoerger, Dana R.; Jakuba, Michael; Shank, Timothy M.; Langmuir, Charles H.; Nakamura, Ko-ichi

    We describe a three-phase use of the Woods Hole Oceanographic Institution's Autonomous Benthic Explorer ( ABE), to locate, map and photograph previously undiscovered fields of high temperature submarine hydrothermal vents. Our approach represents both a complement to and a significant advance beyond the prior state of the art. Previously, hydrothermal exploration relied upon deep-tow instruments equipped with sensors that could locate sites of active "black smoker" venting to within a few kilometers. Follow-on CTD tow-yos could then resolve the sites of seafloor venting to length scales of less than a kilometer but rarely to better than a few hundreds of meters. In our new approach ABE: (i) uses sensors to locate the center of a dispersing non-buoyant hydrothermal plume 100-400 m above the seabed; (ii) makes high-resolution maps of the seafloor beneath the plume center whilst simultaneously detecting interception of any rising, buoyant hydrothermal plumes; and (iii) dives to the seafloor to take photographs in and around any new vent site to characterize its geologic setting and reveal the nature of any chemosynthetic ecosystems it may host. By conducting all of the above under long-baseline navigation, precise sites of venting can be determined to within 5 m. Our approach can be used both to address important scientific issues in their own right and to ensure much more efficient use of other deep-submergence assets such as human occupied vehicles (HOVs) and remotely operated vehicles (ROVs) during follow-on studies.

  6. Long-term impact of bottom trawling on pelagic-benthic coupling in the southern North Sea (German Bight)

    NASA Astrophysics Data System (ADS)

    Friedrich, Jana; van Beusekom, Justus E. E.; Neumann, Andreas; Naderipour, Celine; Janssen, Felix; Ahmerkamp, Soeren; Holtappels, Moritz; Schueckel, Ulrike

    2016-04-01

    The southern North Sea, and the German Bight, has been systematically bottom-trawled at least since the late 19th century (Christiansen, 2009; Reiss et al., 2009; Kröncke 2011; Emeis et al., 2015, Neumann et al., 2016). As a result, benthic habitats and benthic biogenic structures created by bivalves, polychaetes and hydroids where destroyed or reduced. The parallel removal of hard substrate (gravel and boulders) avoids the resettlement of hard-substrate depended species. For example, the Oyster ground, a huge oyster bank a hundred years ago (Olsen, 1883), turned into a muddy depression today. In addition, shallow depth of max 40 m, strong tidal currents and frequent storms result in a high-energy environment with low sedimentation rates and recurrent sediment resuspension. The decrease in benthic filtering capacity by disturbance in epifauna and bottom roughness (Callaway et al., 2007) apparently influence pelagic-benthic coupling of biogeochemical fluxes. Heip et al. (1995) indicate that benthic respiration at depths prevailing in the German Bight accounts for 10-40% of total respiration, whereas pelagic respiration accounts for 60-90%. Previous estimates are in the middle of this range (Heip et al., 1995). To test these hypotheses and to assess the partitioning of benthic and pelagic processes, and the factors influencing organic matter mineralization, we measured pelagic production and respiration based on Winkler titration, in-situ benthic fluxes using chamber landers, we did ex-situ incubations of intact sediment cores and analysed still images from a towed benthic video sled. In addition, O2 fluxes in permeable sediments were estimated by integrating the volumetric rate measurements of the upper sediment layer over in-situ microsensor-measured O2 penetration depth. Our current results show significant seasonality in benthic respiration, with highest rates in summer and lowest rates in winter. No significant differences in total benthic respiration rates

  7. Temporal variation of diatom benthic propagules in a monsoon-influenced tropical estuary

    NASA Astrophysics Data System (ADS)

    Patil, Jagadish S.; Anil, Arga Chandrashekar

    2008-10-01

    Temporal variations in the diatom benthic propagule (DBP) community and their role in the phytoplankton community in a monsoon-affected tropical estuary, Zuari estuary, Goa (India) are presented. The DBP from the sediments was enumerated using an extinction dilution method (most probable number method), which allows estimation of resting stages through examination of germinated vegetative cells in culture. The DBP community was dominated by planktonic species belonging to the genera Skeletonema, Fragilariopsis, Thalassiosira, and Chaetoceros. Benthic propagules (BPs) of Skeletonema costatum and Fragilariopsis sp. were dominant throughout the year. Between these two species, only S. costatum showed a linear relationship between the BP and planktonic cells, indicating that this species is particularly important in coupling of pelagic and benthic ecosystems. During the onset and restart of monsoon after an intermittent break, water column was stratified, with a low-salinity layer arising from riverine discharge and precipitation at the surface and relatively cold, saline, low-oxygen waters at the bottom. Stratification favored blooming of S. costatum and Fragilariopsis sp. in nutrient-rich surface and bottom waters, respectively. The decline in these blooms ensuing nitrate depletion and salinity change resulted in an increased abundance of BP. Chaetoceros bloom was observed during the monsoon break as well as during non-monsoon period and on both the occasions the decline in bloom was coupled with freshwater discharge. During the non-monsoon season, Thalassiosira blooms were encountered subsequent to high nitrate inputs. These findings suggest that in such shallow tropical regions, physical processes during monsoon (freshwater discharge) and non-monsoon seasons (currents, waves and tides) cause resuspension of diatom BP. Since light is not a limiting factor for germination in such regions, the blooming of resuspended BP depends on nutrient availability.

  8. Quo vadis NW Black Sea benthic ecosystems?

    NASA Astrophysics Data System (ADS)

    Traian Gomoiu, Marian

    2016-04-01

    The author briefly presents a general review on the evolution trends of benthic ecosystems at the Romanian Black Sea coast, referring to some recent data from the literature. The Black Sea represents a "unicum hydrobiologicum" by some of its basic characteristics, such as: 1. a large semi-enclosed basin with an intense exchange of waters; 2. a sea receiving a large amount of fresh water, especially in its northwestern sector, brought by the Danube, Dnieper and Dniester Rivers; 3. a large meromictic sea - euxinic-azoic below depths of 150 - 200 m; 4. around the sea there is a large filter-holding belt consisting of bivalves (Mytilus galloprovincialis and Modiolula phaseolina); 5. a sea having in its northwestern sector a large area covered by red algae of the genus Phyllophora; 6. a sea undergoing, in the last 50 years, intense environmental pressures (pollution by large rivers and direct discharges of wastewater from urban areas, the development of maritime traffic, overfishing by bottom trawling, coastal facilities and especially by many defense works of the new port); 7. a sea registering in the last decades of the past century many events of eutrophication; 8. a sea enriching its biodiversity by alien species. After the political and socio-economic changes triggered by the events of 1989 and especially after Romania's accession to EU, the state of the northwestern Black Sea coastal ecosystems, has recorded positive changes: • Decrease in environmental pressures; • Decreasing pollutant / fertilizing discharges into the Danube; • Reduction of domestic sewage quantities from coastal settlements; • Improvement in the quality of the wastewater discharged into the sea; • Reduction of active fishing by bottom trawling; • Adopting and implementing a national / international set of guidelines concerning marine environment; • Adopting regulations on the protection of the marine environment against pollution in marine economy: transport / shipping, tourism

  9. Structure of Benthic Communities along the Taiwan Latitudinal Gradient.

    PubMed

    Ribas-Deulofeu, Lauriane; Denis, Vianney; De Palmas, Stéphane; Kuo, Chao-Yang; Hsieh, Hernyi Justin; Chen, Chaolun Allen

    2016-01-01

    The distribution and the structure of benthic assemblages vary with latitude. However, few studies have described benthic communities along large latitudinal gradients, and patterns of variation are not fully understood. Taiwan, lying between 21.90°N and 25.30°N, is located at the center of the Philippine-Japan arc and lies at the northern margin of coral reef development. A wide range of habitats is distributed along this latitudinal gradient, from extensive fringing coral reefs at the southern coast to non-reefal communities at the north. In this study, we examined the structure of benthic communities around Taiwan, by comparing its assemblages in four regions, analyzing the effects of the latitudinal gradient, and highlighting regional characteristics. A total of 25 sites, 125 transects, and 2,625 photographs were used to analyze the benthic communities. Scleractinian corals present an obvious gradient of increasing diversity from north to south, whereas macro-algae diversity is higher on the north-eastern coast. At the country scale, Taiwanese coral communities were dominated by turf algae (49%). At the regional scale, we observed an important heterogeneity that may be caused by local disturbances and habitat degradation that smooths out regional differences. In this context, our observations highlight the importance of managing local stressors responsible for reef degradation. Overall, this study provides an important baseline upon which future changes in benthic assemblages around Taiwan can be assessed. PMID:27513665

  10. Structure of Benthic Communities along the Taiwan Latitudinal Gradient

    PubMed Central

    De Palmas, Stéphane; Kuo, Chao-Yang; Hsieh, Hernyi Justin; Chen, Chaolun Allen

    2016-01-01

    The distribution and the structure of benthic assemblages vary with latitude. However, few studies have described benthic communities along large latitudinal gradients, and patterns of variation are not fully understood. Taiwan, lying between 21.90°N and 25.30°N, is located at the center of the Philippine-Japan arc and lies at the northern margin of coral reef development. A wide range of habitats is distributed along this latitudinal gradient, from extensive fringing coral reefs at the southern coast to non-reefal communities at the north. In this study, we examined the structure of benthic communities around Taiwan, by comparing its assemblages in four regions, analyzing the effects of the latitudinal gradient, and highlighting regional characteristics. A total of 25 sites, 125 transects, and 2,625 photographs were used to analyze the benthic communities. Scleractinian corals present an obvious gradient of increasing diversity from north to south, whereas macro-algae diversity is higher on the north-eastern coast. At the country scale, Taiwanese coral communities were dominated by turf algae (49%). At the regional scale, we observed an important heterogeneity that may be caused by local disturbances and habitat degradation that smooths out regional differences. In this context, our observations highlight the importance of managing local stressors responsible for reef degradation. Overall, this study provides an important baseline upon which future changes in benthic assemblages around Taiwan can be assessed. PMID:27513665

  11. Structure of Benthic Communities along the Taiwan Latitudinal Gradient.

    PubMed

    Ribas-Deulofeu, Lauriane; Denis, Vianney; De Palmas, Stéphane; Kuo, Chao-Yang; Hsieh, Hernyi Justin; Chen, Chaolun Allen

    2016-01-01

    The distribution and the structure of benthic assemblages vary with latitude. However, few studies have described benthic communities along large latitudinal gradients, and patterns of variation are not fully understood. Taiwan, lying between 21.90°N and 25.30°N, is located at the center of the Philippine-Japan arc and lies at the northern margin of coral reef development. A wide range of habitats is distributed along this latitudinal gradient, from extensive fringing coral reefs at the southern coast to non-reefal communities at the north. In this study, we examined the structure of benthic communities around Taiwan, by comparing its assemblages in four regions, analyzing the effects of the latitudinal gradient, and highlighting regional characteristics. A total of 25 sites, 125 transects, and 2,625 photographs were used to analyze the benthic communities. Scleractinian corals present an obvious gradient of increasing diversity from north to south, whereas macro-algae diversity is higher on the north-eastern coast. At the country scale, Taiwanese coral communities were dominated by turf algae (49%). At the regional scale, we observed an important heterogeneity that may be caused by local disturbances and habitat degradation that smooths out regional differences. In this context, our observations highlight the importance of managing local stressors responsible for reef degradation. Overall, this study provides an important baseline upon which future changes in benthic assemblages around Taiwan can be assessed.

  12. Naturally Ocurring Polyphosphate-accumulating Bacteria in Benthic Biofilms

    NASA Astrophysics Data System (ADS)

    Locke, N. A.; Saia, S. M.; Walter, M. T.; Carrick, H. J.; Buda, A. R.; Regan, J. M.

    2014-12-01

    Polyphosphate accumulating organisms (PAOs), known to store excess phosphorus (P) as polyphosphate (poly-P), influence P transport in the environment. Enhanced biological phosphorus removal (EBPR) from wastewater has long served as a basis to study bacterial PAOs, yet little research has genetically identified similar organisms in natural settings. Aerobic/anaerobic cycles, used to select for PAOs in EBPR, can result from changing environmental conditions such as night/day cycles for benthic biofilms. Benthic biofilms from eight Pennsylvanian streams were studied for naturally-occurring bacterial PAOs similar to those typically found in EBPR systems. PAOs were confirmed in the benthic biofilms by a characteristic yellow fluorescent emission from DAPI staining. Cells containing yellow fluorescence were separated from the rest of the sample using a flow cytometer, resulting in a physically enriched culture of PAOs from the benthic biofilms. Amplicon-based metagenomic sequencing will reveal the phylogeny of bacteria responsible for poly-P accumulation in these benthic biofilms. Sequencing data will be used to develop fluorescent in-situ hybridization (FISH) probes, and hybridizations will be performed on DAPI-stained cells to confirm poly-P accumulation by targeted phylotypes. Identifying PAOs in natural settings is a critical step towards studying environments that support high concentrations of PAOs, serving as significant factors in the P cycle. PAOs can then be connected to P transport models to help understand and mitigate P pollution in agricultural watersheds.

  13. Ecology and role of benthic copepods in northern lakes

    NASA Astrophysics Data System (ADS)

    Sarvala, J.

    1998-06-01

    Freshwater benthic Harpacticoida consist of species capable of swimming, but mostly burrowing in organic sediments, and small, vermiform species that are poor swimmers and live in interstitial systems. Freshwater benthic Cyclopoida are either agile epibenthic and often relatively large herbivores, carnivores and omnivores, or small infaunal omnivores. Harpacticoids seem to have few, mainly invertebrate, predators, and consequently low mortality and long life span. These are evolutionarily linked to slow growth and low production to biomass ratio (typically 1-7 a -1). Cyclopoids are characterized by more rapid growth and higher production to biomass ratio (typically 3-13 a -1). Due to their active mode of life, they are preyed upon by fish and other predators, which results in high mortality and a short adult life span. Harpacticoid numbers and biomass may reach 250,000 ind/m 2 and 120 mgC/m 2. True benthic cyclopoids are usually much less abundant (up to 20,000 ind/m 2 and 9 mgC/m 2). Thus, although the quantitative importance of freshwater meiofauna as a whole may often be comparable to that of macrofauna, the few biomass and production data on benthic copepods suggest that at least harpacticoids have a minor role in the benthic food web of northern lakes.

  14. Detecting Benthic Megafauna in Underwater Video

    NASA Astrophysics Data System (ADS)

    Edgington, D. R.; Kerkez, I.; Oliver, D.; Kuhnz, L.; Cline, D. E.; Walther, D.; Itti, L.

    2004-12-01

    Remotely operated vehicles (ROVs) have revolutionized oceanographic research, supplementing traditional technologies of acoustics and trawling as tools which assess animal diversity, distribution and abundance. Video equipment deployed on ROVs enable quantitative video transects (QVTs) to be recorded from ocean habitats, providing high-resolution imagery on the scale of individual organisms and their associated habitat. Currently, the manual method employed by trained scientists analyzing QVTs is labor-intensive and costly, limiting the amount of data analyzed from ROV dives. An automated system for detecting organisms and identifying objects visible in video would address these concerns. Automated event detection (scene segmentation) is a step towards an automated analytical system for QVTs. In the work presented here, video frames are processed with a neuromorphic selective-attention algorithm. The candidate locations identified by the attention selection module are subject to a number of parameters. These parameters, combined with successful tracking over several frames, determine whether detected events are deemed "interesting" or "boring". "Interesting" events are marked in the video frames for subsequent identification and processing. As reported previously for mid-water QVTs, the system agrees with professional annotations 80% of the time. Poor contrast of small translucent animals in conjunction with the presence of debris ("marine snow") complicates automated event detection. While the visual characteristics of the seafloor (benthic) habitat are very different from the mid-water environment, the system yields a 92% correlation of detected animals on the seafloor compared with professional annotations. We present results detailing the comparison between a) automated detection and b) professional detection and classification, and we outline plans for future development of automated analysis.

  15. Deep water circulation in the eastern Mediterranean Sea for the last 95 kyr: new insights from stable isotopes and benthic foraminiferal assemblages

    NASA Astrophysics Data System (ADS)

    Cornuault, Marine; Vidal, Laurence; Tachikawa, Kazuyo; Licari, Laetitia; Rouaud, Guillaume; Sonzogni, Corinne; Revel, Marie

    2016-04-01

    The response of the Eastern Mediterranean Sea circulation to climate forcing over the last 95 kyr BP was studied using core MD04-2722 collected at 1780m water depth in the Levantine Sea. Foraminiferal stable isotopes and benthic foraminiferal assemblages were combined to reconstruct deep water ventilation and oxygenation in relation to surface water freshening. Over the last deglaciation, benthic foraminiferal δ13C values and benthic foraminiferal oxygen index decreased while δ18O gradient between benthic and planktonic foraminifera increased. These results testify respectively of slower ventilation, bottom water oxygen depletion and stronger stratification prior to S1 sapropel deposition. Similar conditions were deduced for S3 sapropel. Combination of deglacial sea level rise and fresher North Atlantic surface water contribution were evaluated to be a precondition of S1 formation in the Levantine Sea. Local Nile freshwater supply during the African Humid Period further strengthened the water column stratification. For the last glacial period, three events at around 53, 46 and 37 ka BP were marked by benthic δ13C decrease demonstrating deep water circulation reduction at the core location. Bottom water oxygenation was only slightly lowered. Considering the effect of North Atlantic surface water salinity to the Mediterranean Sea circulation, we propose the 46 and 37 ka BP events as responses to the Heinrich Events 4 and 5 that supplied fresher surface water to the Mediterranean Sea. Since the '53 ka event' is characterized by the appearance of an anoxic benthic foraminiferal species observed for S1 and S3 layers, we tentatively attributed it to the 'missing' sapropel S2. Our results indicate that intense stagnation in the Eastern Mediterranean Sea could occur when both local freshwater supply and fresher North Atlantic surface water contributed. The influence of North Atlantic condition was significant on the eastern Mediterranean circulation under warm and cold

  16. Long-term impact of bottom trawling on pelagic-benthic coupling in the southern North Sea (German Bight)

    NASA Astrophysics Data System (ADS)

    Friedrich, Jana; van Beusekom, Justus E. E.; Neumann, Andreas; Naderipour, Celine; Janssen, Felix; Ahmerkamp, Soeren; Holtappels, Moritz; Schueckel, Ulrike

    2016-04-01

    The southern North Sea, and the German Bight, has been systematically bottom-trawled at least since the late 19th century (Christiansen, 2009; Reiss et al., 2009; Kröncke 2011; Emeis et al., 2015, Neumann et al., 2016). As a result, benthic habitats and benthic biogenic structures created by bivalves, polychaetes and hydroids where destroyed or reduced. The parallel removal of hard substrate (gravel and boulders) avoids the resettlement of hard-substrate depended species. For example, the Oyster ground, a huge oyster bank a hundred years ago (Olsen, 1883), turned into a muddy depression today. In addition, shallow depth of max 40 m, strong tidal currents and frequent storms result in a high-energy environment with low sedimentation rates and recurrent sediment resuspension. The decrease in benthic filtering capacity by disturbance in epifauna and bottom roughness (Callaway et al., 2007) apparently influence pelagic-benthic coupling of biogeochemical fluxes. Heip et al. (1995) indicate that benthic respiration at depths prevailing in the German Bight accounts for 10-40% of total respiration, whereas pelagic respiration accounts for 60-90%. Previous estimates are in the middle of this range (Heip et al., 1995). To test these hypotheses and to assess the partitioning of benthic and pelagic processes, and the factors influencing organic matter mineralization, we measured pelagic production and respiration based on Winkler titration, in-situ benthic fluxes using chamber landers, we did ex-situ incubations of intact sediment cores and analysed still images from a towed benthic video sled. In addition, O2 fluxes in permeable sediments were estimated by integrating the volumetric rate measurements of the upper sediment layer over in-situ microsensor-measured O2 penetration depth. Our current results show significant seasonality in benthic respiration, with highest rates in summer and lowest rates in winter. No significant differences in total benthic respiration rates

  17. Benthic foraminiferal assemblage formation: Theory and observation for the European Arctic margin

    NASA Astrophysics Data System (ADS)

    Loubere, Paul; Rayray, Shan

    2016-09-01

    We use theory and observation to determine how benthic foraminiferal populations living in a range of sedimentary microenvironments are translated into fossil assemblages along the continental margin of the European Arctic. We examine downcore stained (cell tracker green and rose Bengal) and total species shell abundances through the sediment mixing (bioturbation) zone. This, in combination with porewater geochemical measurements, allows us to establish zones of production and destruction for species' shells, and deduce how the fossil record is being generated by the living community. For many taxa, shell production is high in the upper, oxic, sedimentary layer, but destruction in this zone is also high. Hence, contribution to the fossil record is biased to more infaunal populations and species. Taxa producing near, or below, the anoxic boundary of the sediments are particularly important to the developing fossil record of the fjord environment. We find that taxon relative and absolute abundances change continuously through the biologically active sediment profile. This has implications for reconstructing paleoenvironments using benthic foraminiferal assemblages, and potentially for the geochemistry of individual fossil taxa.

  18. A Study on Benthic Foraminifera Assemblages in the Upper Slope off Southwest Taiwan

    NASA Astrophysics Data System (ADS)

    Yeh, Jen-Chu; Lin, Andrew T.; Chien, Chih-Wei

    2016-04-01

    This study attempts to establish the spatial distribution of benthic foraminifera in the upper accretionary wedge off SW Taiwan. A few box cores (each core up to 49 cm thick) are retrieved onboard R/V Ocean Researcher I during 1092 cruise in 2014 at water depths ranging from 1,135 to 1,586 m lying in between the Good Weather Ridge and the Yuan-An Ridge. Analyses on grain size reveal that the sediment size ranges from clay to silt for all sites with the exception of YT1 site, where a small percentage of fine sand (< 20%) is found to distribute evenly in a 32 cm-thick box core. Core images from X-radiographs show some layers of foraminifera ooze and rare traces of bioturbation. Age of sedimentation is obtained by using 210Pb dating method. The 210Pb concentration profile decays exponentially down core, indicating sedimentation from suspension. The measured sedimentation rate ranges from 0.47 to 2.4 mm/yr. Site YT1 has the lowest sedimentation rate (around 0.47 mm/yr), leading to high abundance of individual benthic foraminiferal species. Living foraminiferal individuals were distinguished from dead assemblages by Rose Bengal staining method during the cruise. Our results show that the dominant living species of all studied cores is Chilostomella oolina, with subsidiary occurrences of Bulimina aculeata, Bolivinita quadrilateral, and Lenticulina spp. etc. Cluster analysis suggests that the forams have similar spatial distribution pattern at all studied sites, indicating uniform and stable hemipelagic sedimentation. Analyses of dead assemblages reveal a remarkable decrease in the abundance of Bulimina and Uvigerina for the last 100 years at YT-2 site, with increasing abundance of Chilostomella. This indicates that the water masses may have turned from suboxic to dysoxic conditions since c. 100 year ago. This is the first study to report the living benthic foraminifera distribution in water depths up to c. 1,600 m off SW Taiwan, providing a basis for future studies

  19. Benthic metabolic feedbacks to carbonate chemistry on coral reefs:implications for ocean acidification

    NASA Astrophysics Data System (ADS)

    Price, N.; Rohwer, F. L.; Stuart, S. A.; Andersson, A.; Smith, J.

    2012-12-01

    The metabolic activity of resident organisms can cause spatio-temporal variability in carbonate chemistry within the benthic boundary layer, and thus potentially buffer the global impacts of ocean acidification. But, little is known about the capacity for particular species assemblages to contribute to natural daily variability in carbonate chemistry. We encapsulated replicate areas (~3m2) of reef across six Northern Line Islands in the central Pacific for 24 hrs to quantify feedbacks to carbonate chemistry within the benthic boundary layer from community metabolism. Underneath each 'tent', we quantified relative abundance and biomass of each species of corals and algae. We coupled high temporal resolution time series data on the natural diurnal variability in pH, dissolved oxygen, salinity, and temperature (using autonomous sensors) with resident organisms' net community calcification and productivity rates (using change in total dissolved carbon and total alkalinity over time) to examine feedbacks from reef metabolism to boundary layer carbonate chemistry. These reefs experienced large ranges in pH (> 0.2 amplitude) each day, similar to the magnitude of 'acidification' expected over the next century. Daily benthic pH, pCO2, and aragonite saturation state (Ωaragonite) were contrasted with seasonal threshold values estimated from open ocean climatological data extrapolated at each island to determine relative inter-island feedbacks. Diurnal amplitude in pH, pCO2, and Ωaragonite at each island was dependent upon the resident species assemblage of the benthos and was particularly reliant upon the biomass, productivity, and calcification rate of Halimeda. Net primary productivity of fleshy algae (algal turfs and Lobophora spp.) predominated on degraded, inhabited islands where net community calcification was negligible. In contrast, the chemistry over reefs on 'pristine', uninhabited islands was driven largely by net calcification of calcareous algae and stony

  20. Pelagic and benthic ecology of the lower interface of the Eastern Tropical Pacific oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Wishner, Karen F.; Ashjian, Carin J.; Gelfman, Celia; Gowing, Marcia M.; Kann, Lisa; Levin, Lisa A.; Mullineaux, Lauren S.; Saltzman, Jennifer

    1995-01-01

    The distributions of pelagic and benthic fauna were examined in relation to the lower boundary of the oxygen minimum zone (OMZ) on and near Volcano 7, a seamount that penetrates this feature in the Eastern Tropical Pacific. Although the broad, pronounced OMZ in this region is an effective barrier for most zooplankton, zooplankton abundances, zooplankton feeding rates, and ambient suspended particulate organic carbon (POC) peaked sharply in the lower OMZ (about 740-800 m), in association with the minimum oxygen concentration and the increasing oxygen levels just below it. Zooplankton in the lower OMZ were also larger in size, and the pelagic community included some very abundant, possibly opportunistic, species. Elevated POC and scatter in the light transmission data suggested the existence of a thin, particle-rich, and carbon-rich pelagic layer at the base of the OMZ. Gut contents of planktonic detrifvores implied opportunistic ingestion of bacterial aggregates, possibly from this layer. Benthic megafaunal abundances on the seamount, which extended up to 730 m, peaked at about 800 m. There was a consistent vertical progression in the depth of first occurrence of different megafaunal taxa in this depth range, similar to intertidal zonation. Although the vertical gradients of temperature, salinity, and oxygen were gradual at the lower OMZ interface (in contrast to the upper OMZ interface at the thermocline), temporal variability in oxygen levels due to internal wave-induced vertical excursions of the OMZ may produce the distinct zonation in the benthic fauna. The characteristics of the lower OMZ interface result from biological interactions with the chemical and organic matter gradients of the OMZ. Most zooplankton are probably excluded physiologically from pronounced OMZs. The zooplankton abundance peak at the lower interface of the OMZ occurs where oxygen becomes sufficiently high to permit the zooplankton to utilize the high concentrations of organic particles

  1. Spatial and temporal distributions of benthic green macroalgae in Yaquina bay, Oregon

    EPA Science Inventory

    Coastal estuaries of Oregon, USA, typically support relatively large accumulations of benthic green macroalgae (BGM) during the summer/early fall growing season. This raises questions regarding possible (positive and negative) effects on eelgrass and benthic epifauna and infauna...

  2. Application of multiple index development approaches to benthic invertebrate data from the Virginian Biogeographic Province

    EPA Science Inventory

    Benthic invertebrate indices have commonly been utilized to assess benthic invertebrate communities. These indices have been constructed using different techniques, but have shown different levels of application success. For example, the EMAP Virginian Province Index did not pe...

  3. Linkages between benthic macroinvertebrate assemblages and landscape stressors in the US Great Lakes

    EPA Science Inventory

    We used multiple linear regression analysis to investigate relationships between benthic macroinvertebrate assemblages in the nearshore region of the Laurentian Great Lakes and landscape characteristics in adjacent watersheds. Benthic invertebrate data were obtained from the 201...

  4. Spatial Patterns of Subtidal Benthic Invertebrates and Environmental Factors in the Nearshore Gulf of Maine

    EPA Science Inventory

    The spatial patterns of subtidal benthic invertebrates and physical-chemical variables in the nearshore Gulf of Maine (Acadian Biogeographic Province) were studied to provide information needed to calibrate benthic indices of environmental condition, determine physical-chemical f...

  5. RELATIONSHIPS BETWEEN ENVIRONMENTAL VARIABLES AND BENTHIC DIATOM ASSEMBLAGES IN CALIFORNIA CENTRAL VALLEY STREAMS (USA)

    EPA Science Inventory

    Streams and rivers in the California Central Valley Ecoregion have been substantially modified by human activities. This study examines distributional patterns of benthic diatom assemblages in relation to environmental characteristics in streams and rivers of this region. Benthic...

  6. Benthic plastic debris in marine and fresh water environments.

    PubMed

    Corcoran, Patricia L

    2015-08-01

    This review provides a discussion of the published literature concerning benthic plastic debris in ocean, sea, lake, estuary and river bottoms throughout the world. Although numerous investigations of shoreline, surface and near-surface plastic debris provide important information on plastic types, distribution, accumulation, and degradation, studies of submerged plastic debris have been sporadic in the past and have become more prominent only recently. The distribution of benthic debris is controlled mainly by combinations of urban proximity and its association with fishing-related activities, geomorphology, hydrological conditions, and river input. High density plastics, biofouled products, polymers with mineral fillers or adsorbed minerals, and plastic-metal composites all have the potential to sink. Once deposited on the bottoms of water basins and channels, plastics are shielded from UV light, thus slowing the degradation process significantly. Investigations of the interactions between benthic plastic debris and bottom-dwelling organisms will help shed light on the potential dangers of submerged plastic litter.

  7. Benthic plastic debris in marine and fresh water environments.

    PubMed

    Corcoran, Patricia L

    2015-08-01

    This review provides a discussion of the published literature concerning benthic plastic debris in ocean, sea, lake, estuary and river bottoms throughout the world. Although numerous investigations of shoreline, surface and near-surface plastic debris provide important information on plastic types, distribution, accumulation, and degradation, studies of submerged plastic debris have been sporadic in the past and have become more prominent only recently. The distribution of benthic debris is controlled mainly by combinations of urban proximity and its association with fishing-related activities, geomorphology, hydrological conditions, and river input. High density plastics, biofouled products, polymers with mineral fillers or adsorbed minerals, and plastic-metal composites all have the potential to sink. Once deposited on the bottoms of water basins and channels, plastics are shielded from UV light, thus slowing the degradation process significantly. Investigations of the interactions between benthic plastic debris and bottom-dwelling organisms will help shed light on the potential dangers of submerged plastic litter. PMID:26129903

  8. Acute bioassays with benthic macroinvertebrates conducted in situ

    SciTech Connect

    Whaley, M.; Garcia, R.; Sy, J. )

    1989-10-01

    Several methods of toxicity testing using macroinvertebrates in controlled laboratory experiments have been reported. Researchers conducted bioassays with natural assemblages of benthic macroinvertebrates exposed to several petroleum refinery effluents. They found that the populations of invertebrates declined after only a few days of exposure. The objective of the study was to determine the acute toxic effects of discharge water from a petrochemical complex on a natural assemblage of benthic macroinvertebrates. The discharge water consisted of refinery wastewater and sanitary wastewater, as well as brine discharge from a power/desalination plant. The benthic macroinvertebrates were transplanted from a healthy reef area to the outfall channel receiving the discharge water. The study began on October 7, 1985, and concluded that same week. Any decrease in specific species would indicate that the discharge was toxic to these species. These species could also serve as indicators of toxic conditions at other locations.

  9. Clinch River remedial investigation task 9 -- benthic macroinvertebrates

    SciTech Connect

    Scott, E.M. Jr.

    1994-08-01

    This report summarizes the results of Task 9 of the TVA/Department of Energy (DOE) Interagency Agreement supporting DOE`s Clinch River Remedial Investigation. Species lists and densities (numbers/m{sup 2}) of benthic macroinvertebrates sampled at 16 sites in the Clinch River and Poplar Creek embayments of upper Watts Bar Reservoir near Oak Ridge, Tennessee, in March, 1994, are presented and briefly discussed. Data are also analyzed to assess and compare quality of benthic communities at each site, according to methods developed for TVA`s Reservoir Vital Signs Monitoring Program. Results of this study will be incorporated with other program tasks in a comprehensive report prepared by Oak Ridge National Laboratory in 1995, which will, in part, assess the effect of sediment contaminants on benthic macroinvertebrate communities in Watts Bar Reservoir.

  10. Fish stomach contents in benthic macroinvertebrate assemblage assessments.

    PubMed

    Tupinambás, T H; Pompeu, P S; Gandini, C V; Hughes, R M; Callisto, M

    2015-01-01

    The choice of sampling gears to assess benthic macroinvertebrate communities depends on environmental characteristics, study objectives, and cost effectiveness. Because of the high foraging capacity and diverse habitats and behaviors of benthophagous fishes, their stomach contents may offer a useful sampling tool in studies of benthic macroinvertebrates, especially in large, deep, fast rivers that are difficult to sample with traditional sediment sampling gear. Our objective was to compare the benthic macroinvertebrate communities sampled from sediments with those sampled from fish stomachs. We collected benthic macroinvertebrates and fish from three different habitat types (backwater, beach, riffle) in the wet season, drying season, and dry season along a single reach of the Grande River (Paraná River Basin, southeast Brazil). We sampled sediments through use of a Petersen dredge (total of 216 grabs) and used gill nets to sample fish (total of 36 samples). We analyzed the stomach contents of three commonly occurring benthophagous fish species (Eigenmannia virescens, Iheringichthys labrosus, Leporinus amblyrhynchus). Chironomids dominated in both sampling methods. Macroinvertebrate taxonomic composition and abundances from fish stomachs differed from those from sediment samples, but less so from riffles than from backwater and beach habitats. Macroinvertebrate taxa from E. virescens stomachs were more strongly correlated with sediment samples from all three habitats than were those from the other two species. The species accumulation curves and higher mean dispersion values, compared with with sediment samples suggest that E. virescens is more efficient than sediment samples and the other fish studied at collecting benthic taxa. We conclude that by analyzing the stomach contents of benthophagous fishes it is possible to assess important characteristics of benthic communities (dispersion, taxonomic composition and diversity). This is especially true for studies

  11. Rates of Ocean Acidification: Decoupling of Planktic and Benthic Extinctions?

    NASA Astrophysics Data System (ADS)

    Thomas, E.; Alegret, L.

    2012-12-01

    Deep-sea benthic organisms derive food from export of organic matter produced in the photic zone, so that pelagic and benthic productivity are coupled, suggesting that severe extinction of plankton and benthos in the geological past should have been coupled. An asteroid impact at the Cretaceous/Paleogene (K/Pg) boundary (~65 Ma), however, caused mass extinction of calcifying plankton (foraminifera and nannoplankton), whereas benthic calcifyers (foraminifera) did not suffer significant extinction. Also, pelagic calcifyers did not suffer severe extinction during the carbon-cycle perturbation and global warming at the Paleocene-Eocene (P/E) boundary 10 myr later, when deep-sea benthic foraminifera did. The K/Pg extinction has been interpreted as darkness-caused collapse of productivity, but this is not supported by the lack of benthic extinction. To evaluate extinction mechanisms, we compared benthic foraminiferal and stable isotope records at ODP sites in the Pacific, SE Atlantic and Southern Oceans. Across the K/Pg boundary, the decrease in export productivity was moderate, regionally variable, and insufficient to explain the mass extinction at higher levels of the food chain. Across the P/E boundary, productivity increased in epicontinental seas and on continental margins, whereas pelagic productivity may have declined (increased trophic resource continuum). We thus found no evidence that the different benthic and pelagic extinction patterns at K/Pg and P/E were linked to changes in (export) productivity. Instead, the difference between planktic and benthic extinction patterns may have been caused by the occurrence of ocean acidification at different rates. Very rapid (faster than present anthropogenic) surface ocean acidification at the K/Pg boundary may have been due to influx of impact-generated nitric acid, followed by rapid oceanic buffering. This may have been a factor in the massive extinction of pelagic calcifyers, ammonites and top-level predators such as

  12. COMPARISON OF TWO INDICES OF BENTHIC COMMUNITY CONDITION IN CHESAPEAKE BAY

    EPA Science Inventory

    The Chesapeake Benthic Index of Biotic Integrity (B-IBI) and the EMAP-VP Benthic Index were applied to samples from 239 sites in Chesapeake Bay. The B-IBI weights several community measures equally and uses a simple scoring system while the EMAP-VP Benthic Index uses discriminant...

  13. APPLICATION OF TWO INDICES OF BENTHIC COMMUNITY CONDITION IN CHESAPEAKE BAY

    EPA Science Inventory

    The Chesapeake Bay Benthic Index of Biotic Integrity (B-161) and the Environmental Monitoring and Assessment Program's Virginian Province Benthic Index (EMAP-VP BI) were applied to 294 sampling events in Chesapeake Bay and the results were compared. These benthic indices are inte...

  14. REFINEMENT, VALIDATION, AND APPLICATION OF A BENTHIC CONDITION INDEX FOR NORTHERN GULF OF MEXICO ESTUARIES

    EPA Science Inventory

    By applying discriminant analysis to benthic macroinvertebrate data to produce a benthic index, we have developed an indicator of benthic condition for northern Gulf of Mexico estuaries. The data used were collected by the U.S. Environmental Protection Agency's (USEPA) Environmen...

  15. Responses of benthic foraminifera to the 2011 oil spill in the Bohai Sea, PR China.

    PubMed

    Lei, Yan Li; Li, Tie Gang; Bi, Hongsheng; Cui, Wen Lin; Song, Wen Peng; Li, Ji Ye; Li, Cheng Chun

    2015-07-15

    The 2011 oil spill in the Bohai Sea was the largest spill event in China. Nine sediment cores were taken near the spill site and environmental factors including Polycyclic Aromatic Hydrocarbon (PAHs), oils, sulfides, organic carbon were measured 6 months later. Benthic foraminifera were separated into >150 μm (large) and 63-150 μm (small) size fractions for 2-cm depth interval of each sediment core. Statistical analyses suggested that the species composition of living foraminifera was impacted by oils, PAHs and sulfides. Large foraminifera were more sensitive to the oils than the small. Abnormal specimens were positively correlated with oils or PAHs. Small forms, however, tended to have high reproduction and mortality. Pollution-resistant and opportunistic taxa were identified to calculate a Foraminiferal Index of Environmental Impacts (FIEI). The FIEI increased from low to high oil-polluted station and from deep layer to surface sediment reflects the impact of oil pollution in this area. PMID:26002093

  16. Pattern analysis in a benthic bacteria-nutrient system.

    PubMed

    Wetzel, Daniel

    2016-04-01

    We study steady states in a reaction-diffusion system for a benthic bacteria-nutrient model in a marine sediment over 1D and 2D domains by using Landau reductions and numerical path following methods. We point out how the system reacts to changes of the strength of food supply and ingestion. We find that the system has a stable homogeneous steady state for relatively large rates of food supply and ingestion, while this state becomes unstable if one of these rates decreases and Turing patterns such as hexagons and stripes start to exist. One of the main results of the present work is a global bifurcation diagram for solutions over a bounded 2D domain. This bifurcation diagram includes branches of stripes, hexagons, and mixed modes. Furthermore, we find a number of snaking branches of stationary states, which are spatial connections between homogeneous states and hexagons, homogeneous states and stripes as well as stripes and hexagons in parameter ranges, where both corresponding states are stable. The system under consideration originally contains some spatially varying coefficients and with these exhibits layerings of patterns. The existence of spatial connections between different steady states in bistable ranges shows that spatially varying patterns are not necessarily due to spatially varying coefficients. The present work gives another example, where these effects arise and shows how the analytical and numerical observations can be used to detect signs that a marine bacteria population is in danger to die out or on its way to recovery, respectively. We find a type of hexagon patches on a homogeneous background, which seems to be new discovery. We show the first numerically calculated solution-branch, which connects two different types of hexagons in parameter space. We check numerically for bounded domains whether the stability changes for hexagons and stripes, which are extended homogeneously into the third dimension. We find that stripes and one type of

  17. BENTHIC MACROFAUNA AND HABITAT RELATIONSHIPS IN TILLAMOOK BAY

    EPA Science Inventory

    Tillamook Bay is subject to natural and man-made stressors, such as increased nutrients and sediments, which can alter its habitats and, thereby, impact its productivity and ecological resources. The benthic macrofauna are small, sediment-dwelling invertebrates which have strong...

  18. Benthic Species Richness of U.S. Pacific Estuaries

    EPA Science Inventory

    Understanding the spatial distribution of biodiversity is of paramount importance due to the potential consequences of its loss on human welfare. We demonstrate that biodiversity of soft-bottomed estuarine benthic organisms can be predicted with relatively high accuracy at multi...

  19. BENTHIC MACROFAUNA-HABITAT RELATIONSHIPS IN TWO PACIFIC NORTHWEST ESTUARIES

    EPA Science Inventory

    Habitat-based ecological risk assessments rely, in part, on estimates of the ecological value of the habitats at risk. As part of a larger programmatic effort to estimate estuarine habitat values, we determined benthic macrofauna-habitat relationships for 8 intertidal habitats i...

  20. PHOTOINDUCED TOXICITY OF FLUORANTHENE TO SEVEN MARINE BENTHIC CRUSTACEANS

    EPA Science Inventory

    Seven marine benthic crustaceans were exposed in 4 d water-only toxicity tests to five concentrations of fluoranthene.After exposures, mortality (LC50) and the ability to bury in clean sediment (EC50) were determined. Survivors were then exposed to UV radiation for 1 h. The diffe...

  1. Relating Remotely Sensed Optical Variability to Marine Benthic Biodiversity

    PubMed Central

    Herkül, Kristjan; Kotta, Jonne; Kutser, Tiit; Vahtmäe, Ele

    2013-01-01

    Biodiversity is important in maintaining ecosystem viability, and the availability of adequate biodiversity data is a prerequisite for the sustainable management of natural resources. As such, there is a clear need to map biodiversity at high spatial resolutions across large areas. Airborne and spaceborne optical remote sensing is a potential tool to provide such biodiversity data. The spectral variation hypothesis (SVH) predicts a positive correlation between spectral variability (SV) of a remotely sensed image and biodiversity. The SVH has only been tested on a few terrestrial plant communities. Our study is the first attempt to apply the SVH in the marine environment using hyperspectral imagery recorded by Compact Airborne Spectrographic Imager (CASI). All coverage-based diversity measures of benthic macrophytes and invertebrates showed low but statistically significant positive correlations with SV whereas the relationship between biomass-based diversity measures and SV were weak or lacking. The observed relationships did not vary with spatial scale. SV had the highest independent effect among predictor variables in the statistical models of coverage-derived total benthic species richness and Shannon index. Thus, the relevance of SVH in marine benthic habitats was proved and this forms a prerequisite for the future use of SV in benthic biodiversity assessments. PMID:23405180

  2. The Macroevolutionary Interplay Between Planktic Larvae and Benthic Predators

    NASA Astrophysics Data System (ADS)

    Peterson, K. J.

    2004-12-01

    Many marine invertebrates have a complex life cycle whereby the egg, rather than developing directly to the juvenile stage, develops instead into a intermediate larval form which may spend weeks to months feeding in the plankton before it becomes competent to undergo metamorphosis into the benthic juvenile. Because the selective advantages provided to the animal by having a planktotrophic larval stage are largely unknown, the reasons behind their origin and subsequent maintenance over geological time are not well understood. Using both a molecular clock and the fossil record, I show that four primitively non-feeding larval forms evolved sometime between the late Ediacaran and Early Cambrian, and feeding larvae appear to have evolved from non-feeding ancestors sometime between the Late Cambrian and Middle Ordovician in at least five, if not eight, of eight different clades analyzed. Thus, the initial exploitation of the predator-free pelagos by larvae was achieved independently multiple times by the end of the Early Cambrian, most likely driven by benthic predation pressures upon developing eggs and embryos. Then, because the evolution of larval planktotrophy from lecithotrophic ancestors correlates with the dramatic rise in the generic number of benthic suspension feeders in the Early Ordovician, it seems likely that benthic suspension feeding selected for fecundity, and thus indirectly for planktotrophy, in multiple lineages of marine invertebrates by the end of the Middle Ordovician.

  3. DETECTING BENTHIC COMMUNITY DIFFERENCES: INFLUENCE OF STATISTICAL INDEX AND SEASON

    EPA Science Inventory

    An accurate assessment of estuarine condition is critical to determining whether there has been a change from baseline or 'natural' conditions; benthic communities are routinely used as an ecological endpoint to make this assessment. We addressed two issues which arise when attem...

  4. A review of benthic faunal surveys in San Francisco Bay

    USGS Publications Warehouse

    Nichols, Frederic H.

    1973-01-01

    During the past 60 years, considerable effort has been expended in studies of the relations of the biotic community and physicochemical characteristics of San Francisco Bay water. In very recent years these studies have emphasized the relations between the 'state of health' of bottom-living invertebrates (the benthos) and the levels of pollutants in the bay. Benthic organisms, generally sessile, are unable to escape deleterious environmental changes, and they reflect these changes in alterations of normal species composition of assemblages and species abundance. Data that expands understanding of these relations in urbanized areas such as San Francisco Bay are critical. Because of the implications of such data in control of water quality, the U.S. Geological Survey undertook a review of the results and major conclusions of San Francisco Bay benthic surveys. The size and species composition of faunal assemblages are largely controlled by the salinity of the water, the texture of the bottom sediments, and locally by wastes discharged into the bay. Efforts to describe the structure and function of benthic communities of the bay and to quantify the effects of waste discharge on them have been hampered by inconsistent and often faulty sampling methodology and species identification. Studies made show a lack of information on the normal life processes of the organisms concerned. The diversity index (a mathematical expression of the number of kinds of organisms present at a location), commonly used to describe the 'health' of the benthic community, has been employed without regard for the need for standardizing methodology and species identifications or for understanding natural biological processes that affect such mathematical indices. There are few reliable quantitative data on the distribution of benthic organisms in San Francisco Bay with which future assessments of the 'health' of the benthic community might be compared. Methods for study of the benthos must be

  5. Benthic nitrogen loss in the arabian sea off pakistan.

    PubMed

    Sokoll, Sarah; Holtappels, Moritz; Lam, Phyllis; Collins, Gavin; Schlüter, Michael; Lavik, Gaute; Kuypers, Marcel M M

    2012-01-01

    A pronounced deficit of nitrogen (N) in the oxygen minimum zone (OMZ) of the Arabian Sea suggests the occurrence of heavy N-loss that is commonly attributed to pelagic processes. However, the OMZ water is in direct contact with sediments on three sides of the basin. Contribution from benthic N-loss to the total N-loss in the Arabian Sea remains largely unassessed. In October 2007, we sampled the water column and surface sediments along a transect cross-cutting the Arabian Sea OMZ at the Pakistan continental margin, covering a range of station depths from 360 to 1430 m. Benthic denitrification and anammox rates were determined by using (15)N-stable isotope pairing experiments. Intact core incubations showed declining rates of total benthic N-loss with water depth from 0.55 to 0.18 mmol N m(-2) day(-1). While denitrification rates measured in slurry incubations decreased from 2.73 to 1.46 mmol N m(-2) day(-1) with water depth, anammox rates increased from 0.21 to 0.89 mmol N m(-2) day(-1). Hence, the contribution from anammox to total benthic N-loss increased from 7% at 360 m to 40% at 1430 m. This trend is further supported by the quantification of cd(1)-containing nitrite reductase (nirS), the biomarker functional gene encoding for cytochrome cd(1)-Nir of microorganisms involved in both N-loss processes. Anammox-like nirS genes within the sediments increased in proportion to total nirS gene copies with water depth. Moreover, phylogenetic analyses of NirS revealed different communities of both denitrifying and anammox bacteria between shallow and deep stations. Together, rate measurement and nirS analyses showed that anammox, determined for the first time in the Arabian Sea sediments, is an important benthic N-loss process at the continental margin off Pakistan, especially in the sediments at deeper water depths. Extrapolation from the measured benthic N-loss to all shelf sediments within the basin suggests that benthic N-loss may be

  6. Benthic Nitrogen Loss in the Arabian Sea Off Pakistan

    PubMed Central

    Sokoll, Sarah; Holtappels, Moritz; Lam, Phyllis; Collins, Gavin; Schlüter, Michael; Lavik, Gaute; Kuypers, Marcel M. M.

    2012-01-01

    A pronounced deficit of nitrogen (N) in the oxygen minimum zone (OMZ) of the Arabian Sea suggests the occurrence of heavy N-loss that is commonly attributed to pelagic processes. However, the OMZ water is in direct contact with sediments on three sides of the basin. Contribution from benthic N-loss to the total N-loss in the Arabian Sea remains largely unassessed. In October 2007, we sampled the water column and surface sediments along a transect cross-cutting the Arabian Sea OMZ at the Pakistan continental margin, covering a range of station depths from 360 to 1430 m. Benthic denitrification and anammox rates were determined by using 15N-stable isotope pairing experiments. Intact core incubations showed declining rates of total benthic N-loss with water depth from 0.55 to 0.18 mmol N m−2 day−1. While denitrification rates measured in slurry incubations decreased from 2.73 to 1.46 mmol N m−2 day−1 with water depth, anammox rates increased from 0.21 to 0.89 mmol N m−2 day−1. Hence, the contribution from anammox to total benthic N-loss increased from 7% at 360 m to 40% at 1430 m. This trend is further supported by the quantification of cd1-containing nitrite reductase (nirS), the biomarker functional gene encoding for cytochrome cd1-Nir of microorganisms involved in both N-loss processes. Anammox-like nirS genes within the sediments increased in proportion to total nirS gene copies with water depth. Moreover, phylogenetic analyses of NirS revealed different communities of both denitrifying and anammox bacteria between shallow and deep stations. Together, rate measurement and nirS analyses showed that anammox, determined for the first time in the Arabian Sea sediments, is an important benthic N-loss process at the continental margin off Pakistan, especially in the sediments at deeper water depths. Extrapolation from the measured benthic N-loss to all shelf sediments within the basin suggests that benthic N-loss may be

  7. Synthesis of benthic flux components in the Patos Lagooncoastal zone, Rio Grande do Sul, Brazil

    USGS Publications Warehouse

    King, Jeffrey N.

    2012-01-01

    The primary objective of this work is to synthesize components of benthic flux in the Patos Lagoon coastal zone, Rio Grande do Sul, Brazil. Specifically, the component of benthic discharge flux forced by the terrestrial hydraulic gradient is 0.8 m3 d-1; components of benthic discharge and recharge flux associated with the groundwater tidal prism are both 2.1 m3 d-1; components of benthic discharge and recharge flux forced by surface-gravity wave setup are both 6.3 m3 d-1; the component of benthic discharge flux that transports radium-228 is 350 m3 d-1; and components of benthic discharge and recharge flux forced by surface-gravity waves propagating over a porous medium are both 1400 m3 d-1. (All models are normalized per meter shoreline.) Benthic flux is a function of components forced by individual mechanisms and nonlinear interactions that exist between components. Constructive and destructive interference may enhance or diminish the contribution of benthic flux components. It may not be possible to model benthic flux by summing component magnitudes. Geochemical tracer techniques may not accurately model benthic discharge flux or submarine groundwater discharge (SGD). A conceptual model provides a framework on which to quantitatively characterize benthic discharge flux and SGD with a multifaceted approach.

  8. Synthesis of benthic flux components in the Patos Lagoon coastal zone, Rio Grande do Sul, Brazil

    NASA Astrophysics Data System (ADS)

    King, J. N.

    2012-12-01

    The primary objective of this work is to synthesize components of benthic flux in the Patos Lagoon coastal zone, Rio Grande do Sul, Brazil. Specifically, the component of benthic discharge flux forced by the terrestrial hydraulic gradient is 0.8 m3 d-1; components of benthic discharge and recharge flux associated with the groundwater tidal prism are both 2.1 m3 d-1; components of benthic discharge and recharge flux forced by surface-gravity wave setup are both 6.3 m3 d-1; the component of benthic discharge flux that transports radium-228 is 350 m3 d-1; and components of benthic discharge and recharge flux forced by surface-gravity waves propagating over a porous medium are both 1400 m3 d-1. (All models are normalized per meter shoreline.) Benthic flux is a function of components forced by individual mechanisms and nonlinear interactions that exist between components. Constructive and destructive interference may enhance or diminish the contribution of benthic flux components. It may not be possible to model benthic flux by summing component magnitudes. Geochemical tracer techniques may not accurately model benthic discharge flux or submarine groundwater discharge (SGD). A conceptual model provides a framework on which to quantitatively characterize benthic discharge flux and SGD with a multifaceted approach.

  9. Orbital forcing of deep-sea benthic species diversity

    USGS Publications Warehouse

    Cronin, T. M.; Raymo, M.E.

    1997-01-01

    Explanations for the temporal and spatial patterns of species biodiversity focus on stability-time, disturbance-mosaic (biogenic microhabitat heterogeneity) and competition-predation (biotic interactions) hypotheses. The stability-time hypothesis holds that high species diversity in the deep sea and in the tropics reflects long-term climatic stability. But the influence of climate change on deep-sea diversity has not been studied and recent evidence suggests that deep-sea environments undergo changes in climatically driven temperature and flux of nutrients and organic-carbon during glacial-interglacial cycles. Here we show that Pliocene (2.85-2.40 Myr) deep-sea North Atlantic benthic ostracod (Crustacea) species diversity is related to solar insolation changes caused by 41,000-yr cycles of Earth's obliquity (tilt). Temporal changes in diversity, as measured by the Shannon- Weiner index, H(S), correlate with independent climate indicators of benthic foraminiferal oxygen-isotope ratios (mainly ice volume) and ostracod Mg:Ca ratios (bottomwater temperature). During glacial periods, H(S) = 0.2-0.6, whereas during interglacials, H(S) = 1.2-1.6, which is three to four times as high. The control of deep-sea benthic diversity by cyclic climate change at timescales of 103-104 yr does not support the stability-time hypothesis because it shows that the deep sea is a temporally dynamic environment. Diversity oscillations reflect large-scale response of the benthic community to climatically driven changes in either thermohaline circulation, bottom temperature (or temperature-related factors) and food, and a coupling of benthic diversity to surface productivity.

  10. Benthic macrofauna habitat associations in Willapa Bay, Washington, USA

    NASA Astrophysics Data System (ADS)

    Ferraro, Steven P.; Cole, Faith A.

    2007-02-01

    Estuary-wide benthic macrofauna-habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [ Zostera marina], Atlantic cordgrass [ Spartina alterniflora], mud shrimp [ Upogebia pugettensis], ghost shrimp [ Neotrypaea californiensis]) in 1996 and 7 habitats (eelgrass, Atlantic cordgrass, mud shrimp, ghost shrimp, oyster [ Crassostrea gigas], bare mud/sand, subtidal) in 1998. Most benthic macrofaunal species inhabited multiple habitats; however, 2 dominants, a fanworm, Manayunkia aestuarina, in Spartina, and a sand dollar, Dendraster excentricus, in subtidal, were rare or absent in all other habitats. Benthic macrofaunal Bray-Curtis similarity varied among all habitats except eelgrass and oyster. There were significant differences among habitats within- and between-years on several of the following ecological indicators: mean number of species ( S), abundance ( A), biomass ( B), abundance of deposit (AD), suspension (AS), and facultative (AF) feeders, Swartz's index (SI), Brillouin's index ( H), and jackknife estimates of habitat species richness (HSR). In the 4 habitats sampled in both years, A was about 2.5× greater in 1996 (a La Niña year) than 1998 (a strong El Niño year) yet relative values of S, A, B, AD, AS, SI, and H among the habitats were not significantly different, indicating strong benthic macrofauna-habitat associations despite considerable climatic and environmental variability. In general, the rank order of habitats on indicators associated with high diversity and productivity (high S, A, B, SI, H, HSR) was eelgrass = oyster ≥ Atlantic cordgrass ≥ mud shrimp ≥ bare mud/sand ≥ ghost shrimp = subtidal. Vegetation, burrowing shrimp, and oyster density and sediment %silt + clay and %total organic carbon were generally poor, temporally inconsistent predictors of ecological indicator variability within habitats. The benthic macrofauna-habitat associations in this study can be used to help identify

  11. Phototoxicity of TiO2 nanoparticles to a freshwater benthic amphipod: are benthic systems at risk?

    EPA Science Inventory

    This study investigated phototoxicity of TiO2 nanoparticles (nano-TiO2) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was p...

  12. Floating mucus aggregates derived from benthic microorganisms on rocky intertidal reefs: Potential as food sources for benthic animals

    NASA Astrophysics Data System (ADS)

    Tamura, Y.; Tsuchiya, M.

    2011-09-01

    Mucus films, flocs or foams consisting of fine sand, algae and detritus frequently occur in the surface waters of rocky intertidal reef flats during incoming tide. These masses are referred to as mucus aggregates. We examined the developmental process of mucus aggregates and their abundance, distribution, migration and trophic composition. The trophic composition of mucus aggregates was then compared to those of sediments to evaluate their potential nutritional value for benthic animals. The organic matter content, chlorophyll a concentration, microalgal density and bacteria-derived fatty acid contents of mucus aggregates were higher than those observed in sediment, suggesting that mucus aggregates contain not only high levels of organic matter but also dense concentrations of microalgae and bacteria; therefore, mucus aggregates may serve as a qualitatively more energetic food source for benthic fauna compared to sediments. Benthic diatoms were the most abundant organisms in mucus aggregates. Large numbers of diatoms were trapped in fine mineral particles and mucilage-like strings, suggesting that a portion of the mucus is secreted by these benthic microalgae. Mucus aggregate accounted for only 0.01-3.9% of the daily feeding requirements of the dominant detritivore, Ophiocoma scolopendrina (Echinodermata: Ophiuroidea) over the entire sampling area. In contrast, for the species population on the back reef, where mucus aggregates ultimately accumulate, mucus aggregates provided from 0.4 to 113.3% of food for this species. These results suggest that mucus aggregate availability varies spatiotemporally and that they do not always provide adequate food sources for O. scolopendrina populations.

  13. Utilizing Multibeam Bathymetry and Geographic Information Systems (GIS) to Expand Our Mapping Ability of Potential Rockfish Benthic Habitats in the San Juan Islands, Washington

    NASA Astrophysics Data System (ADS)

    Kelly-Slatten, K.

    2013-12-01

    In order to construct an accurate cartographic representation of the potential rockfish habitat zone in the San Juan Archipelago, Washington, bathymetric data is needed to form layers within Geographic Information Systems (GIS) that include, but are not limited to, slope, hillshade, and aspect. Backscatter data is also important in order to demonstrate the induration of the marine floor, which in turn may tell the researcher what type of sediment and substrate makes up that part of the benthic region. Once these layers are added to the GIS map, another layer (referred to as Potential Benthic Habitats) is created and inserted. This layer uses the same induration data but groups them into polygons, which are then color-coded and displayed on the map. With all the layers now pictured, it is clear that the intertidal zones are not complete. Aerial photographs are then added to fill in the gaps according to the GPS coordinates associated with the middle section of each picture. When all pictures and layers have been included, the GIS map is a somewhat three-dimensional, color-coordinated, aerial photograph enhanced depiction of Skipjack, Waldron, Orcas, and Sucia Islands. The bathymetric and backscatter data are plugged into Excel to graphically illustrate specific numbers that represent the various potential habitats. The given data support the idea that potential rockfish habitat (Sedimentary Bedrock and Fractured Bedrock) must be closely monitored and maintained in attempt to preserve and conserve the three either threatened or endangered rockfish species within the Puget Sound locale.

  14. Partitioning of Total Dissolved Salts, Boron and Selenium in Pariette Wetland Water, Sediments and Benthic Organisms

    NASA Astrophysics Data System (ADS)

    Jacobson, A. R.; Jones, C. P.; Vasudeva, P.; Powelson, D.; Grossl, P.

    2014-12-01

    The Pariette Wetlands located in the Uinta Basin, UT, were developed by the BLM in part to mitigate salinity associated with irrigation drainage and runoff from flowing to the Green River, a tributary of the Colorado River. The wetlands are fed by runoff from upstream agricultural irrigation, and natural subsurface and overland flow through the Uintah formation, which is seleniferous, and saline. Concentrations of Total Dissolved Salts (TDS), boron (B) and selenium (Se) in the wetlands exceed the total maximum daily loads developed to meet the US EPA's water quality planning and management regulations (40CFR 130). This is of concern because the wetlands are home to populations of migratory birds, waterfowl, raptors, and numerous small mammals. A mass balance of the Se concentrations of water flowing into and out of the wetlands indicates that 80% of the Se is stored or lost within the system. Additional data suggest that the majority of the Se is associated with the sediments. Little information is available regarding the TDS and B. Therefore we will determine the whether B and other salts are accumulating in the wetland systems, and if so where. We sampled water, sediment, benthic organisms, and wetland plants, in 4 of the 23 ponds from the flood control inlet to water flowing out to the Green River. Sediments were collected at 3 depths (0-2 cm, 2-7 cm, and 7+ cm) at 3-4 locations within each pond including the inlet, outlet and at least one site near a major wetland plant community. Benthic organisms were sampled from the 0-2 cm and 2-7 cm sediment layers. Sediment and organism samples were digested with HNO3 and HClO4 prior to analysis of total Se by HGAAS. Hot water extractable B and DPTA extractable B were analyzed by ICP-AES. TDS was estimated from EC in the sediment and organisms extracts and direct analysis in the water. Preliminary results found that Se in the sediments decreases with depth. Se concentrations in the benthic organisms is approximately 4

  15. Age and correlation of California Paleogene benthic foraminiferal stages

    USGS Publications Warehouse

    Poore, Richard Z.

    1980-01-01

    Comparisons of age determinations and correlations derived from calcareous plankton with those derived from benthic foraminifers in a number of sections in California show significant overlap in time of the Ynezian through the Ulatisian Stages. Thus interbasin time correlations deduced from these stage assignments must be treated with caution. Calcareous plankton occasionally associated with benthic foraminifers diagnostic of the Narizian through the Zemorrian Stages indicate that the Narizian-Refugian boundary is within the upper Eocene of international usage and that the Refugian is entirely upper Eocene. Overlap of the Narizian and the Refugian appears to be minimal. The Zemorrian correlates, mostly, with the Oligocene, although the upper limit of the Zemorrian might be in the lower Miocene.

  16. Underwater microscopy for in situ studies of benthic ecosystems.

    PubMed

    Mullen, Andrew D; Treibitz, Tali; Roberts, Paul L D; Kelly, Emily L A; Horwitz, Rael; Smith, Jennifer E; Jaffe, Jules S

    2016-01-01

    Microscopic-scale processes significantly influence benthic marine ecosystems such as coral reefs and kelp forests. Due to the ocean's complex and dynamic nature, it is most informative to study these processes in the natural environment yet it is inherently difficult. Here we present a system capable of non-invasively imaging seafloor environments and organisms in situ at nearly micrometre resolution. We overcome the challenges of underwater microscopy through the use of a long working distance microscopic objective, an electrically tunable lens and focused reflectance illumination. The diver-deployed instrument permits studies of both spatial and temporal processes such as the algal colonization and overgrowth of bleaching corals, as well as coral polyp behaviour and interspecific competition. By enabling in situ observations at previously unattainable scales, this instrument can provide important new insights into micro-scale processes in benthic ecosystems that shape observed patterns at much larger scales. PMID:27403715

  17. [Impacts of large hydropower station on benthic algal communities].

    PubMed

    Jia, Xing-Huan; Jiang, Wan-Xiang; Li, Feng-Qing; Tang, Tao; Duan, Shu-Gui; Cai, Qing-Hua

    2009-07-01

    To investigate the impacts of large hydropower station in Gufu River on benthic algae, monthly samplings were conducted from September 2004 to June 2007 at the site GF04 which was impacted by the hydropower station, with the site GL03 in Gaolan River as reference. During sampling period, no significant differences were observed in the main physicochemical variables between GF04 and GL03, but the hydrodynamics differed significantly. GL03 was basically at a status of slow flow; while GF04, owing to the discharging from the reservoir, was at a riffle status during more than 60% of the sampling period. Such a difference in hydrodynamics induced significant differences in the community similarity of benthic algae and the relative abundance of unattached diatoms, erect diatoms, and stalked diatoms between GF04 and GL03, which could better reflect the impacts of irregular draw-off by large hydropower station on river eco-system.

  18. Underwater microscopy for in situ studies of benthic ecosystems

    PubMed Central

    Mullen, Andrew D.; Treibitz, Tali; Roberts, Paul L. D.; Kelly, Emily L. A.; Horwitz, Rael; Smith, Jennifer E.; Jaffe, Jules S.

    2016-01-01

    Microscopic-scale processes significantly influence benthic marine ecosystems such as coral reefs and kelp forests. Due to the ocean's complex and dynamic nature, it is most informative to study these processes in the natural environment yet it is inherently difficult. Here we present a system capable of non-invasively imaging seafloor environments and organisms in situ at nearly micrometre resolution. We overcome the challenges of underwater microscopy through the use of a long working distance microscopic objective, an electrically tunable lens and focused reflectance illumination. The diver-deployed instrument permits studies of both spatial and temporal processes such as the algal colonization and overgrowth of bleaching corals, as well as coral polyp behaviour and interspecific competition. By enabling in situ observations at previously unattainable scales, this instrument can provide important new insights into micro-scale processes in benthic ecosystems that shape observed patterns at much larger scales. PMID:27403715

  19. Ural River benthic communities response on the chemical spill

    SciTech Connect

    Tarasov, A.G.

    1995-12-31

    The Ural River is the second river of the North Caspian basin, on the north-west border of the Kazakhstan and Russian. The middle flow of the Ural River is limited by the dam of Iriklin water reservoirs (about 80 km up from Orsk town, Orenburg district) to the mouth of Barbastay River (about 45 km down from Ural`sk town). On 13--17 November 1991, after an industrial incident in Orsk oil refinery enterprise effluent polluted the Ural River. An assessment of the Middle flow Ural River benthic communities by oil and phenols spill response is described. The paper is based on a study of the short-term response of benthic biocenosises compared with natural transformation of the community structure before pollution.

  20. Seafloor geology and benthic habitats, San Pedro Shelf, southern California

    USGS Publications Warehouse

    Wong, Florence L.; Dartnell, Peter; Edwards, Brian D.; Phillips, Eleyne L.

    2012-01-01

    Seafloor samples, videography, still photography, and real-time descriptions of geologic and biologic constituents at or near the seafloor of the San Pedro Shelf, southern California, advance the study of natural and man-made processes on this coastal area off the metropolitan Los Angeles area. Multibeam echo-sounder data collected by the U.S. Geological Survey in 1998 and 1999 guided sampling and camera work in 2004 resulting in a new seafloor character map that shows possible benthic habitats in much higher resolution (4- and 16-m pixels) than previously available. The seafloor is characterized by primarily muddy sand and sand with outcrops of Miocene and Pliocene bedrock along the Palos Verdes Fault Zone. Observed benthic populations indicate low abiotic complexity, low biotic complexity, and low biotic coverage. The data are provided for use in geographic information systems (GIS).

  1. Underwater microscopy for in situ studies of benthic ecosystems

    NASA Astrophysics Data System (ADS)

    Mullen, Andrew D.; Treibitz, Tali; Roberts, Paul L. D.; Kelly, Emily L. A.; Horwitz, Rael; Smith, Jennifer E.; Jaffe, Jules S.

    2016-07-01

    Microscopic-scale processes significantly influence benthic marine ecosystems such as coral reefs and kelp forests. Due to the ocean's complex and dynamic nature, it is most informative to study these processes in the natural environment yet it is inherently difficult. Here we present a system capable of non-invasively imaging seafloor environments and organisms in situ at nearly micrometre resolution. We overcome the challenges of underwater microscopy through the use of a long working distance microscopic objective, an electrically tunable lens and focused reflectance illumination. The diver-deployed instrument permits studies of both spatial and temporal processes such as the algal colonization and overgrowth of bleaching corals, as well as coral polyp behaviour and interspecific competition. By enabling in situ observations at previously unattainable scales, this instrument can provide important new insights into micro-scale processes in benthic ecosystems that shape observed patterns at much larger scales.

  2. Estimating benthic fluxes of trace elements to hypoxic coastal waters using 210Po

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hoon; Kim, Guebuem

    2014-12-01

    The activities of colloidal (10 kDa-0.45 μm) and truly dissolved (<10 kDa) 210Po and 210Pb, dissolved inorganic nutrients, and trace elements (Al, V, Co, Ni, Cu, Mo, Mn, and Fe) were measured in the artificial and saline Lake Shihwa, South Korea in July 2011. The boundary between oxic and hypoxic layers, indexed by NH4+, Mn, and dissolved oxygen, was determined by the pycnocline formed at the depth of 2-4 m. The total activities of 210Po and 210Pb in Lake Shihwa were in the range of 10.5-20.4 dpm 100 L-1 and 6.4 to 9.8 dpm 100 L-1, respectively. The proportions of the truly dissolved, colloidal, and particulate phases were, respectively, 55 ± 6%, 29 ± 5%, and 16 ± 3% for 210Po, and 48 ± 6%, 29 ± 7%, and 23 ± 4% for 210Pb. The activities of 210Po were 20-55% higher than those of 210Pb. The benthic flux of 210Po is determined on the basis of the 210Po mass balance model in the water column. Since the excess activities of dissolved 210Po relative to 210Pb showed a positive correlation with the concentrations of trace elements (except for Al), the benthic fluxes of the trace elements from bottom sediment were successfully calculated using these relationships and the 210Po fluxes. Our study highlights that 210Po can be used as a powerful tracer for estimating trace element fluxes from bottom sediment in a hypoxic environment.

  3. Global warming and mass mortalities of benthic invertebrates in the Mediterranean Sea.

    PubMed

    Rivetti, Irene; Fraschetti, Simonetta; Lionello, Piero; Zambianchi, Enrico; Boero, Ferdinando

    2014-01-01

    Satellite data show a steady increase, in the last decades, of the surface temperature (upper few millimetres of the water surface) of the Mediterranean Sea. Reports of mass mortalities of benthic marine invertebrates increased in the same period. Some local studies interpreted the two phenomena in a cause-effect fashion. However, a basin-wide picture of temperature changes combined with a systematic assessment on invertebrate mass mortalities was still lacking. Both the thermal structure of the water column in the Mediterranean Sea over the period 1945-2011 and all documented invertebrate mass mortality events in the basin are analysed to ascertain if: 1- documented mass mortalities occurred under conditions of positive temperature trends at basin scale, and 2- atypical thermal conditions were registered at the smaller spatial and temporal scale of mass mortality events. The thermal structure of the shallow water column over the last 67 years was reconstructed using data from three public sources: MEDAR-MEDATLAS, World Ocean Database, MFS-VOS programme. A review of the mass mortality events of benthic invertebrates at Mediterranean scale was also carried out. The analysis of in situ temperature profiles shows that the Mediterranean Sea changed in a non-homogeneous fashion. The frequency of mass mortalities is increasing. The areas subjected to these events correspond to positive thermal anomalies. Statistically significant temperature trends in the upper layers of the Mediterranean Sea show an increase of up to 0.07°C/yr for a large fraction of the basin. Mass mortalities are consistent with both the temperature increase at basin scale and the thermal changes at local scale, up to 5.2°C. Our research supports the existence of a causal link between positive thermal anomalies and observed invertebrate mass mortalities in the Mediterranean Sea, invoking focused mitigation initiatives in sensitive areas. PMID:25535973

  4. Global warming and mass mortalities of benthic invertebrates in the Mediterranean Sea.

    PubMed

    Rivetti, Irene; Fraschetti, Simonetta; Lionello, Piero; Zambianchi, Enrico; Boero, Ferdinando

    2014-01-01

    Satellite data show a steady increase, in the last decades, of the surface temperature (upper few millimetres of the water surface) of the Mediterranean Sea. Reports of mass mortalities of benthic marine invertebrates increased in the same period. Some local studies interpreted the two phenomena in a cause-effect fashion. However, a basin-wide picture of temperature changes combined with a systematic assessment on invertebrate mass mortalities was still lacking. Both the thermal structure of the water column in the Mediterranean Sea over the period 1945-2011 and all documented invertebrate mass mortality events in the basin are analysed to ascertain if: 1- documented mass mortalities occurred under conditions of positive temperature trends at basin scale, and 2- atypical thermal conditions were registered at the smaller spatial and temporal scale of mass mortality events. The thermal structure of the shallow water column over the last 67 years was reconstructed using data from three public sources: MEDAR-MEDATLAS, World Ocean Database, MFS-VOS programme. A review of the mass mortality events of benthic invertebrates at Mediterranean scale was also carried out. The analysis of in situ temperature profiles shows that the Mediterranean Sea changed in a non-homogeneous fashion. The frequency of mass mortalities is increasing. The areas subjected to these events correspond to positive thermal anomalies. Statistically significant temperature trends in the upper layers of the Mediterranean Sea show an increase of up to 0.07°C/yr for a large fraction of the basin. Mass mortalities are consistent with both the temperature increase at basin scale and the thermal changes at local scale, up to 5.2°C. Our research supports the existence of a causal link between positive thermal anomalies and observed invertebrate mass mortalities in the Mediterranean Sea, invoking focused mitigation initiatives in sensitive areas.

  5. Red List of macrofaunal benthic invertebrates of the Wadden Sea

    NASA Astrophysics Data System (ADS)

    Petersen, G. H.; Madsen, P. B.; Jensen, K. T.; van Bernem, K. H.; Harms, J.; Heiber, W.; Kröncke, I.; Michaelis, H.; Rachor, E.; Reise, K.; Dekker, R.; Visser, G. J. M.; Wolff, W. J.

    1996-10-01

    In the Wadden Sea, in total, 93 species of macrofaunal benthic invertebrates are threatened in at least one subregion. Of these, 72 species are threatened in the entire area and are therefore placed on the trilateral Red List. 7 species are (probably) extinct in the entire Wadden Sea area. The status of 9 species of macrofaunal invertebrates is critical, 13 species are (probably) endangered, the status of 25 species is (probably) vulnerable and of 17 species (probably) susceptible.

  6. An assessment of seabird influence on Arctic coastal benthic communities

    NASA Astrophysics Data System (ADS)

    Zmudczyńska-Skarbek, Katarzyna; Balazy, Piotr; Kuklinski, Piotr

    2015-04-01

    It is well recognized that seabirds, particularly those nesting in coastal colonies, can provide significant nutrient enrichment to Arctic terrestrial ecosystems. However, little is known about the fate of bird-derived nutrients that return to the marine environment and potentially concentrate below the colonies. To attempt to assess the influence of this potential nutrient enrichment of the coastal benthic community, samples of macroalgae, sea urchins (mainly algivores), and hermit crabs (scavengers) were collected at two Arctic localities (Spitsbergen), (1) below a mixed colony of guillemots and kittiwakes, and (2) in an adjacent geomorphologically similar location not influenced by the seabird colony. A much higher nitrogen stable isotope ratio (δ15N) and total nitrogen content were found in terrestrial plants sampled below the colony than away from it. In benthic macroalgae, however, there were no δ15N differences. This might result from the timing of an intensive growth period in macroalgae in late winter/early spring, when there is little or no runoff from the land, and/or ornithogenic nutrients being directly incorporated by phytoplankton. Sea urchins showed higher δ15N and total N in the control site comparing to the colony-influenced area, suggesting differential food sources in their diet and a role of scavenging/carnivory on higher trophic levels there. Opportunistically feeding hermit crabs showed δ15N and total N enrichment below the seabird colony, suggesting dependence on detritus derived from food chains originating from pelagic producers. Our results indicate that seabirds in the Arctic may fertilize coastal benthic communities through pelagic-benthic coupling, while having no direct impact on bottom primary production.

  7. The benthic fauna of the Northern Bering Sea

    USGS Publications Warehouse

    Rowland, Robert W.

    1973-01-01

    the Macoma balthica community which inhabits the brackish coastal lagoons. These associations were compared with the classic boreal benthic communities of Peterson & Thorson. Although the Bering Sea fauna is compositionally similar to the Scandinavian, the species associations differ markedly. These differences are believed to be due to substrate differences. The Bering Sea sediments are more poorly sorted and patchily distributed than those of Scandinavian waters.

  8. Mobile fishing gear reduces benthic megafaunal production on Georges Bank

    USGS Publications Warehouse

    Hermsen, J.M.; Collie, J.S.; Valentine, P.C.

    2003-01-01

    This study addresses the effect of mobile fishing gear disturbance on benthic megafaunal production on the gravel pavement of northern Georges Bank. From 1994 to 2000, we sampled benthic megafauna with a 1 m Naturalists' dredge at shallow (47 to 62 m) and deep (80 to 90 m) sites. The cessation of fishing in large areas of Georges Bank in January 1995 allowed us to monitor changes in production at a previously disturbed site. Production at a shallow disturbed site varied little over the sampling period (32 to 57 kcal m-2 yr-1) and was markedly lower than production at the nearby recovering site, where production increased from 17 kcal m-2yr -1 in 1994 before the closure to 215 kcal m-2 yr -1 in 2000. Atlantic sea scallops Placopecten magellanicus and green sea urchins Strongylocentrotus droebachiensis dominated production at the recovering site. The community production:biomass ratio decreased over time at the recovering site as the sea scallop population matured. At the deep sites, production remained significantly higher at undisturbed sites (174 to 256 kcal m-2 yr-1) than at disturbed sites (30 to 52 kcal m -2 yr-1). The soft-bodied tube-building polychaete Thelepus cincinnatus dominated production at the undisturbed site, while hard-shelled bivalve molluscs Astarte spp. and P. magellanicus were prevalent at the disturbed site. Mobile fishing gear disturbance has a conspicuous effect on benthic megafaunal production in this hard-bottom habitat. Cessation of mobile fishing has resulted in a marked increase in benthic megafaunal production. These findings should help fishery managers to gauge the costs and benefits of management tools such as area closures and low-impact fishing gears.

  9. Reservoir vital signs monitoring, 1991: Benthic macroinvertebrate community results

    SciTech Connect

    Masters, A.E.

    1992-08-01

    As part of an extensive Reservoir Monitoring program to examine the ecological health of reservoirs in the TVA system, benthic communities were sampled and evaluated at 41 locations on 14 TVA reservoirs. Up to ten dredge samples were collected at locations from the forebay, inflow and transition zones. Surveys were conducted between mid-March and mid-April, 1991. The results of these surveys are presented and discussed in this report.

  10. Zebra mussel effects on benthic invertebrates: physical or biotic?

    USGS Publications Warehouse

    Botts, P. Silver; Patterson, Benjamin A.; Schloesser, Don W.

    1996-01-01

    In soft sediments, Dreissena spp. create firm substrate in the form of aggregates of living mussels (druses) that roll free on the sediments. Druses provide physical structure which increases habitat heterogeneity, and the mussels increase benthic organic matter through the production of pseudofeces and feces. Descriptive and experimental studies were used to determine: 1) whether the density of benthic invertebrates in soft sediments increased in the presence of druses, and 2) whether the invertebrate assemblage responded to the physical structure provided by a druse or to some biotic effect associated with the presence of living mussels. In core samples collected biweekly during summer in Presque Isle Bay, Erie, Pennsylvania, amphipods, chironomids, oligochaetes, turbellarians, and hydrozoans were significantly more abundant in sand with druses than in bare sand. When mesh bags containing either a living druse, non-living druse, or no druse were incubated in the bay for 33 d, we found that chironomids were significantly more abundant in treatments with living druses than with non-living druses, and in treatments with non-living druses than with no druse; turbellarians, amphipods, and hydrozoans were significantly more abundant in treatments with living or non-living druses than with no druse; oligochaetes showed no significant differences among treatments. This study demonstrates that most taxa of benthic invertebrates in soft substrate respond specifically to the physical structure associated with aggregates of mussel shells, but further study is needed to examine chironomid responses to some biotic effect dependent on the presence of living mussels.

  11. Traditional Ecological Knowledge and the mapping of benthic marine habitats.

    PubMed

    Teixeira, João Batista; Martins, Agnaldo Silva; Pinheiro, Hudson Tercio; Secchin, Nelio Augusto; Leão de Moura, Rodrigo; Bastos, Alex Cardoso

    2013-01-30

    Traditional Ecological Knowledge (TEK) is the empirically accumulated knowledge of local communities whose livelihoods depend directly on natural resources. TEK has a considerable potential as a reliable, rapid and low cost information source. However, its use for decision making in environmental management is frequently challenged due to the lack of scientific validation and the multiple and poorly understood biases deriving from measurement and analytical errors, as well as from political, cultural and religious sources. During the planning stage of a Marine Protected Area (MPA) in Southeastern Brazil we assessed fisherfolk TEK regarding seabed features, comparing it with results from a conventional oceanographic assessment. TEK was acquired and synthesized during a survey involving 19 fishing villages and a consensus analysis that minimized variation among individual fisherfolks and communities. The oceanographic survey included high resolution benthic habitat mapping tools such as sidescan sonar and ground-truthing with SCUBA near the interfaces of benthic features identified by fisherfolk. Nearly 3000 km(2) of seafloor were mapped by local fisherfolk as "gravel", "sand", "mud" and "reef structures", while side-scan sonar surveys covered approximately 360 km with an average 400 m swath. Analyses of overlap and proximity showed that TEK is relatively cost-effective and accurate for large-scale benthic surveys, especially as a starting point for planning oceanographic surveys. Moreover, including TEK in the planning stage of MPAs may increase communities' participation and understanding of the costs and benefits of the new access and fishing effort regulations.

  12. Modern benthic foraminifer distribution in the Amerasian Basin, Arctic Ocean

    USGS Publications Warehouse

    Ishman, S.E.; Foley, K.M.

    1996-01-01

    A total of 38 box cores were collected from the Amerasian Basin, Arctic Ocean during the U.S. Geological Survey 1992 (PI92-AR) and 1993 (PI93-AR) Arctic Cruises aboard the U.S. Coast Guard Icebreaker Polar Star. In addition, the cruises collected geophysical data, piston cores and hydrographic data to address the geologic and oceanographic history of the western Arctic Ocean. This paper reports the results of the quantitative analyses of benthic foraminifer distribution data of the total (live + dead) assemblages derived from 22 box core-top samples. The results show that a distinct depth distribution of three dominant benthic foraminifer assemblages, the Textularia spp. - Spiroplectammina biformis, Cassidulina teretis and Oridorsalis tener - Eponides tumidulus Biofacies are strongly controlled by the dominant water masses within the Canada Basin: the Arctic Surface Water, Arctic Intermediate Water and Canada Basin Deep Water. The faunal distributions and their oceanographic associations in the Canada Basin are consistent with observations of benthic foraminifer distributions from other regions within the Arctic Ocean.

  13. Sediment toxicity and benthic communities in mildly contaminated mudflats

    SciTech Connect

    Nipper, M.G.; Roper, D.S.; Williams, E.K.; Martin, M.L.; Van Dam, L.F.; Mills, G.N.

    1998-03-01

    Sediment physicochemical characteristics, benthic community structure, and toxicity were measured at reference and contaminated intertidal mudflats around the North Island of New Zealand. Chronic whole-sediment toxicity tests were conducted with the estuarine amphipod, Chaetocorophium lucasi and the marine bivalve, Macomona lilana, and pore-water toxicity tests were conducted with embryos of the echinoid, Fellaster zelandiae. Although concentrations of organic chemicals and heavy metals were up to several orders of magnitude higher at the sites considered to be contaminated, levels of contamination were relatively low compared to internationally based sediment quality guidelines. Although no pronounced difference was found in benthic community structure between reference and contaminated sites, multivariate analysis indicated that natural sediment characteristics and factors related to contamination may have been affecting community structure. Although benthic effects caused by present levels of contamination are not yet dramatic, subtle changes in community structure related to pollution may be occurring. The two whole-sediment and the pore-water toxicity tests presented different response patterns. Growth of C. lucasi and M. liliana was a less sensitive endpoint than survival. None of the three toxicity tests responded more strongly to the contaminated than to the reference sites, that is, neither natural-sediment and pore-water characteristics nor unmeasured contaminants affected the test organisms. It is possible that sediment collection and handling may have induced chemical changes, confounding interpretation of toxicity tests.

  14. Surviving mass extinction by bridging the benthic/planktic divide

    PubMed Central

    Darling, Kate F.; Thomas, Ellen; Kasemann, Simone A.; Seears, Heidi A.; Smart, Christopher W.; Wade, Christopher M.

    2009-01-01

    Evolution of planktic organisms from benthic ancestors is commonly thought to represent unidirectional expansion into new ecological domains, possibly only once per clade. For foraminifera, this evolutionary expansion occurred in the Early–Middle Jurassic, and all living and extinct planktic foraminifera have been placed within 1 clade, the Suborder Globigerinina. The subsequent radiation of planktic foraminifera in the Jurassic and Cretaceous resulted in highly diverse assemblages, which suffered mass extinction at the end of the Cretaceous, leaving an impoverished assemblage dominated by microperforate triserial and biserial forms. The few survivor species radiated to form diverse assemblages once again in the Cenozoic. There have, however, long been doubts regarding the monophyletic origin of planktic foraminifera. We present surprising but conclusive genetic evidence that the Recent biserial planktic Streptochilus globigerus belongs to the same biological species as the benthic Bolivina variabilis, and geochemical evidence that this ecologically flexible species actively grows within the open-ocean surface waters, thus occupying both planktic and benthic domains. Such a lifestyle (tychopelagic) had not been recognized as adapted by foraminifera. Tychopelagic are endowed with great ecological advantage, enabling rapid recolonization of the extinction-susceptible pelagic domain from the benthos. We argue that the existence of such forms must be considered in resolving foraminiferal phylogeny. PMID:19574452

  15. Effects of an oil spill on benthic community production and respiration on subtropical intertidal sandflats.

    PubMed

    Lee, Li-Hua; Lin, Hsing-Juh

    2013-08-15

    This study determined effects of an oil spill on subtropical benthic community production and respiration by monitoring CO2 fluxes in benthic chambers on intertidal sandflats during emersion before and after an accidental spill. The oil spill decreased sediment chlorophyll a concentrations, altered benthic macrofaunal community, and affected ecological functioning by suppressing or even stopping microalgal production, increasing bacterial respiration, and causing a shift from an autotrophic system to a heterotrophic system. Effects of the oil spill on the macrofauna were more severe than on benthic microalgae, and affected sedentary infauna more than motile epifauna. Despite the oil spill's impact on the benthic community and carbon metabolism, the affected area appeared to return to normal in about 23 days. Our results suggest that the prompt response of benthic metabolism to exposure to petroleum hydrocarbons can serve as a useful indicator of the impact of an oil spill.

  16. An assessment of benthic condition in several small watersheds of the Chesapeake Bay, USA.

    PubMed

    Leight, Andrew K; Slacum, Ward H; Wirth, Ed F; Fulton, Mike H

    2011-05-01

    We examined benthic condition in three small watersheds in the Chesapeake Bay. Characterization of benthic condition was based on the combined measurements of benthic fauna, sediment toxicity, and sediment contaminant loads. Significant differences between watersheds were detected for sediment contaminant concentrations and water quality. The intensity of benthic impairment was greatest in the river surrounded by the most developed watershed. Spatial patterns of benthic condition were detected within all three watersheds. In contrast to current, intense focus on nutrient pollution in the Chesapeake Bay, qualitative comparison of our findings to land-use patterns supports findings of other studies that suggest benthic condition in tributaries of the Chesapeake Bay may more closely relate to urbanization than agricultural land uses.

  17. Do benthic biofilters contribute to sustainability and restoration of the benthic environment impacted by offshore cage finfish aquaculture?

    PubMed

    Aguado-Giménez, F; Piedecausa, M A; Carrasco, C; Gutiérrez, J M; Aliaga, V; García-García, B

    2011-08-01

    Benthic biofilters were deployed under a cage fish farm and in two reference locations to assess the influence of the farm on the biofilters and the surroundings, as well as to verify the usefulness of this technology as a mitigation tool. The biofilters underneath the farm recruited a fouling community practically identical to that of the control biofilters, which included a variety of trophic strategies. The former showed a higher 15N enrichment, indicating that fouling beneath the farm was benefiting from the farm waste. The waste retention efficiency was low (0.02 g N m(-2) month(-1)) beneath the farm. Benthic biofilters aggregated demersal wild fish around and within them. Pelagic wild fish also frequently used the biofilters beneath the farm, forming compact shoals around them. The increased complexity of the habitat below the fish farm enhanced biodiversity, but this improvement did not lead to the recovery of the sediments around the biofilters.

  18. USGS-NPS Servicewide Benthic Mapping Program (SBMP) workshop report

    USGS Publications Warehouse

    Moses, Christopher S.; Nayagandhi, Amar; Brock, John; Beavers, Rebecca

    2010-01-01

    The National Park Service (NPS) Inventory and Monitoring (I&M) Program recently allocated funds to initiate a benthic mapping program in ocean and Great Lakes parks in alignment with the NPS Ocean Park Stewardship 2007-2008 Action Plan. Seventy-four (ocean and Great Lakes) parks, spanning more than 5,000 miles of coastline, many affected by increasing coastal storms and other natural and anthropogenic processes, make the development of a Servicewide Benthic Mapping Program (SBMP) timely. The resulting maps and associated reports will be provided to NPS managers in a consistent servicewide format to help park managers protect and manage the 3 million acres of submerged National Park System natural and cultural resources. Of the 74 ocean and Great Lakes park units, the 40 parks with submerged acreage will be the focus in the early years of the SBMP. The NPS and U.S. Geological Survey (USGS) convened a workshop (June 3-5, 2008) in Lakewood, CO. The assembly of experts from the NPS and other Federal and non-Federal agencies clarified the needs and goals of the NPS SBMP and was one of the key first steps in designing the benthic mapping program. The central needs for individual parks, park networks, and regions identified by workshop participants were maps including bathymetry, bottom type, geology, and biology. This workshop, although not an exhaustive survey of data-acquisition technologies, highlighted the more promising technologies being used, existing sources of data, and the need for partnerships to leverage resources. Workshop products include recommended classification schemes and management approaches for consistent application and products similar to other long-term NPS benthic mapping efforts. As part of the SBMP, recommendations from this workshop, including application of an improved version of the Coastal and Marine Ecological Classification Standard (CMECS), will be tested in several pilot parks. In 2008, in conjunction with the findings of this workshop

  19. Multi- and hyperspectral remote sensing of tropical marine benthic habitats

    NASA Astrophysics Data System (ADS)

    Mishra, Deepak R.

    Tropical marine benthic habitats such as coral reef and associated environments are severely endangered because of the environmental degradation coupled with hurricanes, El Nino events, coastal pollution and runoff, tourism, and economic development. To monitor and protect this diverse environment it is important to not only develop baseline maps depicting their spatial distribution but also to document their changing conditions over time. Remote sensing offers an important means of delineating and monitoring coral reef ecosystems. Over the last twenty years the scientific community has been investigating the use and potential of remote sensing techniques to determine the conditions of the coral reefs by analyzing their spectral characteristics from space. One of the problems in monitoring coral reefs from space is the effect of the water column on the remotely sensed signal. When light penetrates water its intensity decreases exponentially with increasing depth. This process, known as water column attenuation, exerts a profound effect on remotely sensed data collected over water bodies. The approach presented in this research focuses on the development of semi-analytical models that resolves the confounding influence water column attenuation on substrate reflectance to characterize benthic habitats from high resolution remotely sensed imagery on a per-pixel basis. High spatial resolution satellite and airborne imagery were used as inputs in the models to derive water depth and water column optical properties (e.g., absorption and backscattering coefficients). These parameters were subsequently used in various bio-optical algorithms to deduce bottom albedo and then to classify the benthos, generating a detailed map of benthic habitats. IKONOS and QuickBird multispectral satellite data and AISA Eagle hyperspectral airborne data were used in this research for benthic habitat mapping along the north shore of Roatan Island, Honduras. The AISA Eagle classification was

  20. More rapid shift to a benthic niche in larger Gadus morhua juveniles.

    PubMed

    Ólafsdóttir, G Á; Gunnarsson, G S; Karlsson, H

    2015-08-01

    Trophic use by Atlantic cod Gadus morhua juveniles was examined early and late in the shift from pelagic to benthic habitats. Changes in the proportion of pelagic copepods, estimates of benthic prey indicated by isotope mixing models and stable-isotope values between sample periods suggested a gradual shift towards a benthic niche. Values of the trophic proxies, however, changed most markedly in the largest juvenile group, suggesting a more rapid trophic niche shift, and in turn competitive advantage, of larger juveniles.

  1. A Servicewide Benthic Mapping Program for National Parks

    USGS Publications Warehouse

    Moses, Christopher S.; Nayegandhi, Amar; Beavers, Rebecca; Brock, John

    2010-01-01

    In 2007, the National Park Service (NPS) Inventory and Monitoring Program directed the initiation of a benthic habitat mapping program in ocean and coastal parks in alignment with the NPS Ocean Park Stewardship 2007-2008 Action Plan. With 74 ocean and Great Lakes parks stretching over more than 5,000 miles of coastline across 26 States and territories, this Servicewide Benthic Mapping Program (SBMP) is essential. This program will deliver benthic habitat maps and their associated inventory reports to NPS managers in a consistent, servicewide format to support informed management and protection of 3 million acres of submerged National Park System natural and cultural resources. The NPS and the U.S. Geological Survey (USGS) convened a workshop June 3-5, 2008, in Lakewood, Colo., to discuss the goals and develop the design of the NPS SBMP with an assembly of experts (Moses and others, 2010) who identified park needs and suggested best practices for inventory and mapping of bathymetry, benthic cover, geology, geomorphology, and some water-column properties. The recommended SBMP protocols include servicewide standards (such as gap analysis, minimum accuracy, final products) as well as standards that can be adapted to fit network and park unit needs (for example, minimum mapping unit, mapping priorities). SBMP Mapping Process. The SBMP calls for a multi-step mapping process for each park, beginning with a gap assessment and data mining to determine data resources and needs. An interagency announcement of intent to acquire new data will provide opportunities to leverage partnerships. Prior to new data acquisition, all involved parties should be included in a scoping meeting held at network scale. Data collection will be followed by processing and interpretation, and finally expert review and publication. After publication, all digital materials will be archived in a common format. SBMP Classification Scheme. The SBMP will map using the Coastal and Marine Ecological

  2. BENTHIC MACROINVERTEBRATES AS INDICATORS OF ENVIRONMENTAL CONDITION IN THREE GREAT LAKES

    EPA Science Inventory

    Biological, physical, and chemical data were collected from surficial sediments of Lakes Ontario, Michigan, and Superior to examine benthic macroinvertebrate community structure as an indicator of environmental condition.

  3. Timing of active methane seep events in the eastern margin of the Japan Sea based on benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Oi, T.

    2015-12-01

    We study the late Quaternary assemblages and stable isotope analyses of benthic foraminifera from the marine core sediments around three methane seep area in the eastern margin of the Japan Sea. Study samples are collected on the Umitaka Spur (MD179-3304), a west part of the Oki Trough (UT14-PC1303&PC1305), and a north part of the Mogami Trough (HR14-RC1408). Each sedimentation rate is calculated by the ages of 14C, tephra, oxygen isotope events, and bottoms of the thin laminated layer.Obvious occurrences of the methane related foraminifera, Rutherfordoides sp., are found from three all core sediments, and these sedimentation ages range to 28-25ka, early part of the MIS 2. However, we never find the unique occurrences from RC1408 sections except of MIS 2 even if another low stand stage of MIS 6. Above Rutherfordoides distributions, rare benthic foraminiferal number shows an anoxic bottom condition where most benthic foraminifera couldn't live during the LGM (Oba et al., 1991), nonetheless, Rutherfordoides sp. lived continuously until the LGM. From the surface sediments, Rutherfordoides cornuta, lives on plural area from the northwest Pacific but not from the Japan Sea (Matoba and Nakagawa, 2009) is related to high methane gas content of the sediments in the Sagami Bay (Akimoto et al., 1996). Nakagawa et al. (2009) reported that distributions of Rutherfordoides rotundata (closely related R. cornuta) indicate that an expulsion of a large amount of methane occurred on the Umitaka Spur during the LGM due to a massive dissociation of subsurface methane hydrate. And, the negative carbon isotope peak signal of Rutherfordoides sp. from RC1408 in the Mogami Trough, also indicate to dissociations of methane hydrate and active methane seeps by the lowest sea level same as Umitaka Spur (Takeuchi et al., 2007). Acknowledgement This research was a part of METI's project entitled "FY2014 Promoting research and development on methane hydrate" .

  4. Application of a spectrofluorimetric tool (bbe BenthoTorch) for monitoring potentially toxic benthic cyanobacteria in rivers.

    PubMed

    Echenique-Subiabre, Isidora; Dalle, Caroline; Duval, Charlotte; Heath, Mark W; Couté, Alain; Wood, Susanna A; Humbert, Jean-François; Quiblier, Catherine

    2016-09-15

    Over the last decade reports of animal poisoning following accidental consumption of neurotoxin-producing benthic cyanobacteria (mainly Phormidium spp.) have increased. There is a need for rapid and cost-effective tools to survey benthic cyanobacteria. In this study we assessed the performance of the BenthoTorch, a fluorometric probe that provides in situ estimations of cyanobacteria, diatoms and green algae biomass in biofilms. Biofilms (n = 288) were analysed from two rivers in France and eight in New Zealand. Correlations between chlorophyll-a measured using the BenthoTorch and spectrophotometry were higher for thin (<2 mm) compared to thick (>2 mm) biofilms (r(2) = 0.58 and 0.27 respectively; p < 0.001). When cyanobacteria represented less than 50% of the total biomass (based on biovolumes), microscopic and BenthoTorch compositional estimations were significantly correlated (r(2) = 0.53, p < 0.001). Conversely, there was no correlation when cyanobacteria exceeded 50% of the total biomass. Under this scenario diatoms were overestimated. Our results suggest that the observed biases occur because the BenthoTorch only measures the upper biofilm layer and it underestimates the biomass of phycoerythrin-containing cyanobacteria. To improve the performance of this sensor and render it a useful tool for a rapid evaluation of benthic cyanobacterial biomass in rivers, we propose that: (i) the algorithms based on the LEDs responses currently available on this tool need revision, (ii) new excitation wavelengths should be included that allow the fingerprints of phycoerythrin-containing cyanobacteria to be discriminated, and (iii) a sensor that penetrates the biofilms is needed to obtain more accurate estimates of cyanobacterial biomass. PMID:27286469

  5. Orbital-scale stratigraphy and paleoenvironmental changes in the Japan Sea during the last 230 kyr based on oxygen and carbon isotopes of benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Nakahashi, K.; Kimoto, K.; Tada, R.; Tamaki, K.

    2009-12-01

    Paleoceanographic conditions in the Japan Sea changed drastically during the late Quaternary in association with orbital and suborbital cycles and glacio-eustatic sea level changes. However, few studies had been examined long-term sediment records older than last intergracial period because of the lack of long cores which contains continuous paleoclimatic records and difficulties reconstructing high-resolution age models. Especially disappearance of benthic foraminifers by euxinic bottom water conditions during glacial maxima makes it difficult to understand specific bottom water environments. In this study, we reconstructed benthic foraminiferal stable isotopic stratigraphy of the Japan Sea core with the resolution in 2 kyr. and compared the global stack of benthic foraminfieral δ18O curve (LR04, Lisiecki & Raymo, 2005). The investigated core MD01-2408, was recovered from 806 m water depth, off Akita Prefecture during IMAGES VII cruise. It had recorded continuous paleoenvironmental histories during the last 230 kyr through the core. This core was mainly consisted of alternating layers of homogeneous light colored silty clay and laminated or bioturbated dark colored silty clay, occasionally intercalating volcanic ash layers. The most abundant benthic foraminiferal species are Uvigerina akitaensis, Angulogerina kokozuraensis and Islandiella norcrossi. Abundance of these species fluctuated drastically through the core. No benthic foraminifera is found in two dark layer intervals 4 ~ 5 mbsf and 25 ~ 25.5 mbsf, corresponding 15 ~ 25 kyr and 149 ~ 152 kyr, respectively, probably representing super anoxic bottom water conditions(Oba et al 1984 1991;Tada et al., 1999). δ18O of U. akitaensis and A. kokozuraensis showed a similar values with a precision of ± 0.27‰ and it was inferred that both species had similar habitat. δ18O of both species in core MD01-2408 fluctuated with the range of 2‰ over 230 kyr. Although benthic δ18O stack of LR04 reached to 5 ‰ during

  6. Boundary Layer

    NASA Technical Reports Server (NTRS)

    Loitsianskii. L. G.

    1956-01-01

    The fundamental, practically the most important branch of the modern mechanics of a viscous fluid or a gas, is that branch which concerns itself with the study of the boundary layer. The presence of a boundary layer accounts for the origin of the resistance and lift force, the breakdown of the smooth flow about bodies, and other phenomena that are associated with the motion of a body in a real fluid. The concept of boundary layer was clearly formulated by the founder of aerodynamics, N. E. Joukowsky, in his well-known work "On the Form of Ships" published as early as 1890. In his book "Theoretical Foundations of Air Navigation," Joukowsky gave an account of the most important properties of the boundary layer and pointed out the part played by it in the production of the resistance of bodies to motion. The fundamental differential equations of the motion of a fluid in a laminar boundary layer were given by Prandtl in 1904; the first solutions of these equations date from 1907 to 1910. As regards the turbulent boundary layer, there does not exist even to this day any rigorous formulation of this problem because there is no closed system of equations for the turbulent motion of a fluid. Soviet scientists have done much toward developing a general theory of the boundary layer, and in that branch of the theory which is of greatest practical importance at the present time, namely the study of the boundary layer at large velocities of the body in a compressed gas, the efforts of the scientists of our country have borne fruit in the creation of a new theory which leaves far behind all that has been done previously in this direction. We shall herein enumerate the most important results by Soviet scientists in the development of the theory of the boundary layer.

  7. A decline in benthic foraminifera following the deepwater horizon event in the northeastern Gulf of Mexico.

    PubMed

    Schwing, Patrick T; Romero, Isabel C; Brooks, Gregg R; Hastings, David W; Larson, Rebekka A; Hollander, David J

    2015-01-01

    Sediment cores were collected from three sites (1000-1200 m water depth) in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic foraminiferal density related to the Deepwater Horizon (DWH) event (April-July 2010, 1500 m water depth). Short-lived radioisotope geochronologies (²¹⁰Pb, ²³⁴Th), organic geochemical assessments, and redox metal concentrations were determined to relate changes in sediment accumulation rate, contamination, and redox conditions with benthic foraminiferal density. Cores collected in December 2010 indicated a decline in density (80-93%). This decline was characterized by a decrease in benthic foraminiferal density and benthic foraminiferal accumulation rate (BFAR) in the surface 10 mm relative to the down-core mean in all benthic foraminifera, including the dominant genera (Bulimina spp., Uvigerina spp., and Cibicidoides spp.). Cores collected in February 2011 documented a site-specific response. There was evidence of a recovery in the benthic foraminiferal density and BFAR at the site closest to the wellhead (45 NM, NE). However, the site farther afield (60 NM, NE) recorded a continued decline in benthic foraminiferal density and BFAR down to near-zero values. This decline in benthic foraminiferal density occurred simultaneously with abrupt increases in sedimentary accumulation rates, polycyclic aromatic hydrocarbon (PAH) concentrations, and changes in redox conditions. Persistent reducing conditions (as many as 10 months after the event) in the surface of these core records were a possible cause of the decline. Another possible cause was the increase (2-3 times background) in PAH's, which are known to cause benthic foraminifera mortality and inhibit reproduction. Records of benthic foraminiferal density coupled with short-lived radionuclide geochronology and organic geochemistry were effective in quantifying the benthic response and will continue to be a valuable tool in determining the long

  8. A Decline in Benthic Foraminifera following the Deepwater Horizon Event in the Northeastern Gulf of Mexico

    PubMed Central

    Schwing, Patrick T.; Romero, Isabel C.; Brooks, Gregg R.; Hastings, David W.; Larson, Rebekka A.; Hollander, David J.

    2015-01-01

    Sediment cores were collected from three sites (1000–1200 m water depth) in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic foraminiferal density related to the Deepwater Horizon (DWH) event (April-July 2010, 1500 m water depth). Short-lived radioisotope geochronologies (210Pb, 234Th), organic geochemical assessments, and redox metal concentrations were determined to relate changes in sediment accumulation rate, contamination, and redox conditions with benthic foraminiferal density. Cores collected in December 2010 indicated a decline in density (80–93%). This decline was characterized by a decrease in benthic foraminiferal density and benthic foraminiferal accumulation rate (BFAR) in the surface 10 mm relative to the down-core mean in all benthic foraminifera, including the dominant genera (Bulimina spp., Uvigerina spp., and Cibicidoides spp.). Cores collected in February 2011 documented a site-specific response. There was evidence of a recovery in the benthic foraminiferal density and BFAR at the site closest to the wellhead (45 NM, NE). However, the site farther afield (60 NM, NE) recorded a continued decline in benthic foraminiferal density and BFAR down to near-zero values. This decline in benthic foraminiferal density occurred simultaneously with abrupt increases in sedimentary accumulation rates, polycyclic aromatic hydrocarbon (PAH) concentrations, and changes in redox conditions. Persistent reducing conditions (as many as 10 months after the event) in the surface of these core records were a possible cause of the decline. Another possible cause was the increase (2–3 times background) in PAH’s, which are known to cause benthic foraminifera mortality and inhibit reproduction. Records of benthic foraminiferal density coupled with short-lived radionuclide geochronology and organic geochemistry were effective in quantifying the benthic response and will continue to be a valuable tool in determining the long

  9. A decline in benthic foraminifera following the deepwater horizon event in the northeastern Gulf of Mexico.

    PubMed

    Schwing, Patrick T; Romero, Isabel C; Brooks, Gregg R; Hastings, David W; Larson, Rebekka A; Hollander, David J

    2015-01-01

    Sediment cores were collected from three sites (1000-1200 m water depth) in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic foraminiferal density related to the Deepwater Horizon (DWH) event (April-July 2010, 1500 m water depth). Short-lived radioisotope geochronologies (²¹⁰Pb, ²³⁴Th), organic geochemical assessments, and redox metal concentrations were determined to relate changes in sediment accumulation rate, contamination, and redox conditions with benthic foraminiferal density. Cores collected in December 2010 indicated a decline in density (80-93%). This decline was characterized by a decrease in benthic foraminiferal density and benthic foraminiferal accumulation rate (BFAR) in the surface 10 mm relative to the down-core mean in all benthic foraminifera, including the dominant genera (Bulimina spp., Uvigerina spp., and Cibicidoides spp.). Cores collected in February 2011 documented a site-specific response. There was evidence of a recovery in the benthic foraminiferal density and BFAR at the site closest to the wellhead (45 NM, NE). However, the site farther afield (60 NM, NE) recorded a continued decline in benthic foraminiferal density and BFAR down to near-zero values. This decline in benthic foraminiferal density occurred simultaneously with abrupt increases in sedimentary accumulation rates, polycyclic aromatic hydrocarbon (PAH) concentrations, and changes in redox conditions. Persistent reducing conditions (as many as 10 months after the event) in the surface of these core records were a possible cause of the decline. Another possible cause was the increase (2-3 times background) in PAH's, which are known to cause benthic foraminifera mortality and inhibit reproduction. Records of benthic foraminiferal density coupled with short-lived radionuclide geochronology and organic geochemistry were effective in quantifying the benthic response and will continue to be a valuable tool in determining the long

  10. Flow enhances photosynthesis in marine benthic autotrophs by increasing the efflux of oxygen from the organism to the water.

    PubMed

    Mass, Tali; Genin, Amatzia; Shavit, Uri; Grinstein, Mor; Tchernov, Dan

    2010-02-01

    Worldwide, many marine coastal habitats are facing rapid deterioration due in part to human-driven changes in habitat characteristics, including changes in flow patterns, a factor known to greatly affect primary production in corals, algae, and seagrasses. The effect of flow traditionally is attributed to enhanced influx of nutrients and dissolved inorganic carbon (DIC) across the benthic boundary layer from the water to the organism however, here we report that the organism's photosynthetic response to changes in the flow is nearly instantaneous, and that neither nutrients nor DIC limits this rapid response. Using microelectrodes, dual-pulse amplitude-modulated fluorometry, particle image velocimetry, and real time mass-spectrometry with the common scleractinian coral Favia veroni, the alga Gracilaria cornea, and the seagrass Halophila stipulacea, we show that this augmented photosynthesis is due to flow-driven enhancement of oxygen efflux from the organism to the water, which increases the affinity of the RuBisCO to CO(2). No augmentation of photosynthesis was found in the absence of flow or when flow occurred, but the ambient concentration of oxygen was artificially elevated. We suggest that water motion should be considered a fundamental factor, equivalent to light and nutrients, in determining photosynthesis rates in marine benthic autotrophs.

  11. Benthic phosphorus cycling in the Peruvian oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Lomnitz, U.; Sommer, S.; Dale, A. W.; Löscher, C. R.; Noffke, A.; Wallmann, K.; Hensen, C.

    2015-10-01

    Oxygen minimum zones (OMZs) that impinge on continental margins favor the release of phosphorus (P) from the sediments to the water column, enhancing primary productivity and the maintenance or expansion of low-oxygen waters. A comprehensive field program in the Peruvian OMZ was undertaken to identify the sources of benthic P, including the analysis of particles from the water column, surface sediments and pore fluids as well as in situ benthic flux measurements. A major fraction of solid phase P was bound as particulate inorganic P (PIP) both in the water column and in sediments. Sedimentary PIP increased with depth in the sediment at the expense of particulate organic P (POP). The ratio of particulate organic carbon (POC) to POP exceeded the Redfield Ratio both in the water column (202 ± 29) and in surface sediments (303 ± 77). However, the POC to total particulate P (TPP = POP + PIP) ratio was close to Redfield in the water column (103 ± 9) and in sediment samples (102 ± 15) taken from the core of the OMZ. This observation suggests that the burial efficiencies of POC and TPP are similar under the low oxygen conditions prevailing in the Peruvian OMZ. Benthic fluxes of dissolved P were extremely high (up to 1.04 ± 0.31 mmol m-2 d-1) and exceeded the fluxes resulting from the degradation of particulate organic matter raining to the seabed. Most of the excess P may have been released by bacterial mats that had stored P during previous periods when bottom waters were less reducing. At one station located at the lower rim of the OMZ, dissolved P was taken up by the sediments indicating recent phosphorite formation.

  12. Deep-sea benthic footprint of the deepwater horizon blowout.

    PubMed

    Montagna, Paul A; Baguley, Jeffrey G; Cooksey, Cynthia; Hartwell, Ian; Hyde, Larry J; Hyland, Jeffrey L; Kalke, Richard D; Kracker, Laura M; Reuscher, Michael; Rhodes, Adelaide C E

    2013-01-01

    The Deepwater Horizon (DWH) accident in the northern Gulf of Mexico occurred on April 20, 2010 at a water depth of 1525 meters, and a deep-sea plume was detected within one month. Oil contacted and persisted in parts of the bottom of the deep-sea in the Gulf of Mexico. As part of the response to the accident, monitoring cruises were deployed in fall 2010 to measure potential impacts on the two main soft-bottom benthic invertebrate groups: macrofauna and meiofauna. Sediment was collected using a multicorer so that samples for chemical, physical and biological analyses could be taken simultaneously and analyzed using multivariate methods. The footprint of the oil spill was identified by creating a new variable with principal components analysis where the first factor was indicative of the oil spill impacts and this new variable mapped in a geographic information system to identify the area of the oil spill footprint. The most severe relative reduction of faunal abundance and diversity extended to 3 km from the wellhead in all directions covering an area about 24 km(2). Moderate impacts were observed up to 17 km towards the southwest and 8.5 km towards the northeast of the wellhead, covering an area 148 km(2). Benthic effects were correlated to total petroleum hydrocarbon, polycyclic aromatic hydrocarbons and barium concentrations, and distance to the wellhead; but not distance to hydrocarbon seeps. Thus, benthic effects are more likely due to the oil spill, and not natural hydrocarbon seepage. Recovery rates in the deep sea are likely to be slow, on the order of decades or longer.

  13. Disturbance, colonization and development of Antarctic benthic communities.

    PubMed

    Barnes, David K A; Conlan, Kathleen E

    2007-01-29

    A decade has yielded much progress in understanding polar disturbance and community recovery-mainly through quantifying ice scour rates, other disturbance levels, larval abundance and diversity, colonization rates and response of benthos to predicted climate change. The continental shelf around Antarctica is clearly subject to massive disturbance, but remarkably across so many scales. In summer, millions of icebergs from sizes smaller than cars to larger than countries ground out and gouge the sea floor and crush the benthic communities there, while the highest wind speeds create the highest waves to pound the coast. In winter, the calm associated with the sea surface freezing creates the clearest marine water in the world. But in winter, an ice foot encases coastal life and anchor ice rips benthos from the sea floor. Over tens and hundreds of thousands of years, glaciations have done the same on continental scales-ice sheets have bulldozed the seabed and the zoobenthos to edge of shelves. We detail and rank modern disturbance levels (from most to least): ice; asteroid impacts; sediment instability; wind/wave action; pollution; UV irradiation; volcanism; trawling; non-indigenous species; freshwater inundation; and temperature stress. Benthic organisms have had to recolonize local scourings and continental shelves repeatedly, yet a decade of studies have demonstrated that they have (compared with lower latitudes) slow tempos of reproduction, colonization and growth. Despite massive disturbance levels and slow recolonization potential, the Antarctic shelf has a much richer fauna than would be expected for its area. Now, West Antarctica is among the fastest warming regions and its organisms face new rapid changes. In the next century, temperature stress and non-indigenous species will drastically rise to become dominant disturbances to the Antarctic life. Here, we describe the potential for benthic organisms to respond to disturbance, focusing particularly on what we

  14. Northern Florida reef tract benthic metabolism scaled by remote sensing

    USGS Publications Warehouse

    Brock, J.C.; Yates, K.K.; Halley, R.B.; Kuffner, I.B.; Wright, C.W.; Hatcher, B.G.

    2006-01-01

    Holistic rates of excess organic carbon production (E) and calcification for a 0.5 km2 segment of the backreef platform of the northern Florida reef tract (NFRT) were estimated by combining biotope mapping using remote sensing with community metabolic rates determined with a benthic incubation system. The use of ASTER multispectral satellite imaging for the spatial scaling of benthic metabolic processes resulted in errors in E and net calcification (G) of 48 and 431% respectively, relative to estimates obtained using AISA hyperspectral airborne scanning. At 19 and 125%, the E and G errors relative to the AISA-based estimates were less pronounced for an analysis that used IKONOS multispectral satellite imagery to spatially extrapolate the chamber process measurements. Our scaling analysis indicates that the holistic calcification rate of the backreef platform of the northern Florida reef tract is negligible at 0.07 g CaCO3 m-2 d-1. All of the mapped biotopes in this reef zone are net heterotrophic, resulting in an estimated holistic excess production rate of -0.56 g C m-2 d-1, and an overall gross primary production to respiration ratio of 0.85. Based on our finding of ubiquitous heterotrophy, we infer that the backreef platform of the NFRT is a sink for external inputs of suspended particulate organic matter. Further, our results suggest that the inward advection of inorganic nutrients is not a dominant forcing mechanism for benthic biogeochemical function in the NFRT. We suggest that the degradation of the northern Florida reef tract may parallel the community phase shifts documented within other reef systems polluted by organic detritus.

  15. Disturbance, colonization and development of Antarctic benthic communities

    PubMed Central

    Barnes, David K.A; Conlan, Kathleen E

    2006-01-01

    A decade has yielded much progress in understanding polar disturbance and community recovery—mainly through quantifying ice scour rates, other disturbance levels, larval abundance and diversity, colonization rates and response of benthos to predicted climate change. The continental shelf around Antarctica is clearly subject to massive disturbance, but remarkably across so many scales. In summer, millions of icebergs from sizes smaller than cars to larger than countries ground out and gouge the sea floor and crush the benthic communities there, while the highest wind speeds create the highest waves to pound the coast. In winter, the calm associated with the sea surface freezing creates the clearest marine water in the world. But in winter, an ice foot encases coastal life and anchor ice rips benthos from the sea floor. Over tens and hundreds of thousands of years, glaciations have done the same on continental scales—ice sheets have bulldozed the seabed and the zoobenthos to edge of shelves. We detail and rank modern disturbance levels (from most to least): ice; asteroid impacts; sediment instability; wind/wave action; pollution; UV irradiation; volcanism; trawling; non-indigenous species; freshwater inundation; and temperature stress. Benthic organisms have had to recolonize local scourings and continental shelves repeatedly, yet a decade of studies have demonstrated that they have (compared with lower latitudes) slow tempos of reproduction, colonization and growth. Despite massive disturbance levels and slow recolonization potential, the Antarctic shelf has a much richer fauna than would be expected for its area. Now, West Antarctica is among the fastest warming regions and its organisms face new rapid changes. In the next century, temperature stress and non-indigenous species will drastically rise to become dominant disturbances to the Antarctic life. Here, we describe the potential for benthic organisms to respond to disturbance, focusing particularly on what

  16. Benthic buffers and boosters of ocean acidification on coral reefs

    NASA Astrophysics Data System (ADS)

    Anthony, K. R. N.; Diaz-Pulido, G.; Verlinden, N.; Tilbrook, B.; Andersson, A. J.

    2013-02-01

    Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (pn) and calcification (gn). Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to changes in seawater aragonite saturation state (Ωa). Results of flume studies showed a hierarchy of responses across groups, depending on CO2 level, time of day and water flow. At low CO2 (350-450 μatm), macroalgae (Chnoospora implexa), turfs and sand elevated Ωa of the flume water by around 0.10 to 1.20 h-1 - normalised to contributions from 1 m2 of benthos to a 1 m deep water column. The rate of Ωa increase in these groups was doubled under acidification (560-700 μatm) and high flow (35 compared to 8 cm s-1). In contrast, branching corals (Acropora aspera) increased Ωa by 0.25 h-1 at ambient CO2 (350-450 μatm) during the day, but reduced Ωa under acidification and high flow. Nighttime changes in Ωa by corals were highly negative (0.6-0.8 h-1) and exacerbated by acidification. Calcifying macroalgae (Halimeda spp.) raised Ωa by day (by around 0.13 h-1), but lowered Ωa by a similar or higher amount at night. Analyses of carbon flux contributions from four different benthic compositions to the reef water carbon chemistry across Heron Reef flat and lagoon indicated that the net lowering of Ωa by coral-dominated areas can to some extent be countered by long water residence times in neighbouring areas dominated by turfs, macroalgae and potentially sand.

  17. Antarctic Porifera database from the Spanish benthic expeditions.

    PubMed

    Rios, Pilar; Cristobo, Javier

    2014-01-01

    THE INFORMATION ABOUT THE SPONGES IN THIS DATASET IS DERIVED FROM THE SAMPLES COLLECTED DURING FIVE SPANISH ANTARCTIC EXPEDITIONS: Bentart 94, Bentart 95, Gebrap 96, Ciemar 99/00 and Bentart 2003. Samples were collected in the Antarctic Peninsula and Bellingshausen Sea at depths ranging from 4 to 2044 m using various sampling gears. The Antarctic Porifera database from the Spanish benthic expeditions is unique as it provides information for an under-explored region of the Southern Ocean (Bellingshausen Sea). It fills an information gap on Antarctic deep-sea sponges, for which there were previously very few data. This phylum is an important part of the Antarctic biota and plays a key role in the structure of the Antarctic marine benthic community due to its considerable diversity and predominance in different areas. It is often a dominant component of Southern Ocean benthic communities. The quality of the data was controlled very thoroughly with GPS systems onboard the R/V Hesperides and by checking the data against the World Porifera Database (which is part of the World Register of Marine Species, WoRMS). The data are therefore fit for completing checklists, inclusion in biodiversity pattern analysis and niche modelling. The authors can be contacted if any additional information is needed before carrying out detailed biodiversity or biogeographic studies. The dataset currently contains 767 occurrence data items that have been checked for systematic reliability. This database is not yet complete and the collection is growing. Specimens are stored in the author's collection at the Spanish Institute of Oceanography (IEO) in the city of Gijón (Spain). The data are available in GBIF.

  18. Antarctic Porifera database from the Spanish benthic expeditions

    PubMed Central

    Rios, Pilar; Cristobo, Javier

    2014-01-01

    Abstract The information about the sponges in this dataset is derived from the samples collected during five Spanish Antarctic expeditions: Bentart 94, Bentart 95, Gebrap 96, Ciemar 99/00 and Bentart 2003. Samples were collected in the Antarctic Peninsula and Bellingshausen Sea at depths ranging from 4 to 2044 m using various sampling gears. The Antarctic Porifera database from the Spanish benthic expeditions is unique as it provides information for an under-explored region of the Southern Ocean (Bellingshausen Sea). It fills an information gap on Antarctic deep-sea sponges, for which there were previously very few data. This phylum is an important part of the Antarctic biota and plays a key role in the structure of the Antarctic marine benthic community due to its considerable diversity and predominance in different areas. It is often a dominant component of Southern Ocean benthic communities. The quality of the data was controlled very thoroughly with GPS systems onboard the R/V Hesperides and by checking the data against the World Porifera Database (which is part of the World Register of Marine Species, WoRMS). The data are therefore fit for completing checklists, inclusion in biodiversity pattern analysis and niche modelling. The authors can be contacted if any additional information is needed before carrying out detailed biodiversity or biogeographic studies. The dataset currently contains 767 occurrence data items that have been checked for systematic reliability. This database is not yet complete and the collection is growing. Specimens are stored in the author’s collection at the Spanish Institute of Oceanography (IEO) in the city of Gijón (Spain). The data are available in GBIF. PMID:24843257

  19. Antarctic sea ice losses drive gains in benthic carbon drawdown.

    PubMed

    Barnes, D K A

    2015-09-21

    Climate forcing of sea-ice losses from the Arctic and West Antarctic are blueing the poles. These losses are accelerating, reducing Earth's albedo and increasing heat absorption. Subarctic forest (area expansion and increased growth) and ice-shelf losses (resulting in new phytoplankton blooms which are eaten by benthos) are the only significant described negative feedbacks acting to counteract the effects of increasing CO2 on a warming planet, together accounting for uptake of ∼10(7) tonnes of carbon per year. Most sea-ice loss to date has occurred over polar continental shelves, which are richly, but patchily, colonised by benthic animals. Most polar benthos feeds on microscopic algae (phytoplankton), which has shown increased blooms coincident with sea-ice losses. Here, growth responses of Antarctic shelf benthos to sea-ice losses and phytoplankton increases were investigated. Analysis of two decades of benthic collections showed strong increases in annual production of shelf seabed carbon in West Antarctic bryozoans. These were calculated to have nearly doubled to >2x10(5) tonnes of carbon per year since the 1980s. Annual production of bryozoans is median within wider Antarctic benthos, so upscaling to include other benthos (combined study species typically constitute ∼3% benthic biomass) suggests an increased drawdown of ∼2.9x10(6) tonnes of carbon per year. This drawdown could become sequestration because polar continental shelves are typically deeper than most modern iceberg scouring, bacterial breakdown rates are slow, and benthos is easily buried. To date, most sea-ice losses have been Arctic, so, if hyperboreal benthos shows a similar increase in drawdown, polar continental shelves would represent Earth's largest negative feedback to climate change.

  20. Deep-sea benthic footprint of the deepwater horizon blowout.

    PubMed

    Montagna, Paul A; Baguley, Jeffrey G; Cooksey, Cynthia; Hartwell, Ian; Hyde, Larry J; Hyland, Jeffrey L; Kalke, Richard D; Kracker, Laura M; Reuscher, Michael; Rhodes, Adelaide C E

    2013-01-01

    The Deepwater Horizon (DWH) accident in the northern Gulf of Mexico occurred on April 20, 2010 at a water depth of 1525 meters, and a deep-sea plume was detected within one month. Oil contacted and persisted in parts of the bottom of the deep-sea in the Gulf of Mexico. As part of the response to the accident, monitoring cruises were deployed in fall 2010 to measure potential impacts on the two main soft-bottom benthic invertebrate groups: macrofauna and meiofauna. Sediment was collected using a multicorer so that samples for chemical, physical and biological analyses could be taken simultaneously and analyzed using multivariate methods. The footprint of the oil spill was identified by creating a new variable with principal components analysis where the first factor was indicative of the oil spill impacts and this new variable mapped in a geographic information system to identify the area of the oil spill footprint. The most severe relative reduction of faunal abundance and diversity extended to 3 km from the wellhead in all directions covering an area about 24 km(2). Moderate impacts were observed up to 17 km towards the southwest and 8.5 km towards the northeast of the wellhead, covering an area 148 km(2). Benthic effects were correlated to total petroleum hydrocarbon, polycyclic aromatic hydrocarbons and barium concentrations, and distance to the wellhead; but not distance to hydrocarbon seeps. Thus, benthic effects are more likely due to the oil spill, and not natural hydrocarbon seepage. Recovery rates in the deep sea are likely to be slow, on the order of decades or longer. PMID:23950956

  1. Antarctic sea ice losses drive gains in benthic carbon drawdown.

    PubMed

    Barnes, D K A

    2015-09-21

    Climate forcing of sea-ice losses from the Arctic and West Antarctic are blueing the poles. These losses are accelerating, reducing Earth's albedo and increasing heat absorption. Subarctic forest (area expansion and increased growth) and ice-shelf losses (resulting in new phytoplankton blooms which are eaten by benthos) are the only significant described negative feedbacks acting to counteract the effects of increasing CO2 on a warming planet, together accounting for uptake of ∼10(7) tonnes of carbon per year. Most sea-ice loss to date has occurred over polar continental shelves, which are richly, but patchily, colonised by benthic animals. Most polar benthos feeds on microscopic algae (phytoplankton), which has shown increased blooms coincident with sea-ice losses. Here, growth responses of Antarctic shelf benthos to sea-ice losses and phytoplankton increases were investigated. Analysis of two decades of benthic collections showed strong increases in annual production of shelf seabed carbon in West Antarctic bryozoans. These were calculated to have nearly doubled to >2x10(5) tonnes of carbon per year since the 1980s. Annual production of bryozoans is median within wider Antarctic benthos, so upscaling to include other benthos (combined study species typically constitute ∼3% benthic biomass) suggests an increased drawdown of ∼2.9x10(6) tonnes of carbon per year. This drawdown could become sequestration because polar continental shelves are typically deeper than most modern iceberg scouring, bacterial breakdown rates are slow, and benthos is easily buried. To date, most sea-ice losses have been Arctic, so, if hyperboreal benthos shows a similar increase in drawdown, polar continental shelves would represent Earth's largest negative feedback to climate change. PMID:26394097

  2. Hydrologic controls on basin-scale distribution of benthic macroinvertebrates

    NASA Astrophysics Data System (ADS)

    Bertuzzo, E.; Ceola, S.; Singer, G. A.; Battin, T. J.; Montanari, A.; Rinaldo, A.

    2013-12-01

    The presentation deals with the role of streamflow variability on basin-scale distributions of benthic macroinvertebrates. Specifically, we present a probabilistic analysis of the impacts of the variability along the river network of relevant hydraulic variables on the density of benthic macroinvertebrate species. The relevance of this work is based on the implications of the predictability of macroinvertebrate patterns within a catchment on fluvial ecosystem health, being macroinvertebrates commonly used as sensitive indicators, and on the effects of anthropogenic activity. The analytical tools presented here outline a novel procedure of general nature aiming at a spatially-explicit quantitative assessment of how near-bed flow variability affects benthic macroinvertebrate abundance. Moving from the analytical characterization of the at-a-site probability distribution functions (pdfs) of streamflow and bottom shear stress, a spatial extension to a whole river network is performed aiming at the definition of spatial maps of streamflow and bottom shear stress. Then, bottom shear stress pdf, coupled with habitat suitability curves (e.g., empirical relations between species density and bottom shear stress) derived from field studies are used to produce maps of macroinvertebrate suitability to shear stress conditions. Thus, moving from measured hydrologic conditions, possible effects of river streamflow alterations on macroinvertebrate densities may be fairly assessed. We apply this framework to an Austrian river network, used as benchmark for the analysis, for which rainfall and streamflow time-series and river network hydraulic properties and macroinvertebrate density data are available. A comparison between observed vs "modeled" species' density in three locations along the examined river network is also presented. Although the proposed approach focuses on a single controlling factor, it shows important implications with water resources management and fluvial

  3. Benthic macroinvertebrate richness along Sausal Creek, Oakland, California

    NASA Astrophysics Data System (ADS)

    Lara, D.; Ahumada, E.; Leon, Y.; Bracho, H.; Telles, C.

    2012-12-01

    Sausal Creek, 5.0 km long, is one of the principal watercourses in Oakland, California. The headwaters of Sausal Creek arise in the Oakland Hills and the creek flows southwestward through the city, discharging into the tidal canal that separates the island of Alameda from Oakland; the creek ultimately flows into San Francisco Bay. Due to the presence of rainbow trout, the stream health of Sausal Creek is a local conservation priority. In the present study, a survey of benthic macroinvertebrates in the creek was conducted and possible correlations between environmental variables and taxonomic richness were analyzed. Three stations along the creek were sampled using a 30.5cm 500 micron aquatic d-net, and temperature, pH and dissolved oxygen levels were measured in creek samples obtained at each station. Temperature, pH and dissolved oxygen levels remained constant along the creek. Taxonomic richness was highest at the upstream site of Palo Seco, located in an eastern section of the creek, and furthest downstream at Dimond Park, in the western portion of the creek. The Monterrey site, just west of Palo Seco was found to be significantly low in benthic macroinvertebrates. The Palo Seco and Monterrey sites are separated by Highway 13 and storm drain inputs may bring contaminants into the creek at this site. At the Monterrey site Sausal Creek follows the Hayward Fault, gas emissions or change in substrate may also affect the local population of benthic invertebrates. Further research will be conducted to determine what factors are contributing to this local anomaly.

  4. Spallanzani Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    31 March 2006 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a layered, light-toned mesa among other layered materials exposed in a mound that covers much of the floor of Spallanzani Crater.

    Location near: 58.3oS, 273.9oW Image width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Summer

  5. Ecological periodic tables for benthic macrofaunal usage of estuarine habitats : Insights from a case study in Tillamook bay, Oregon, USA

    EPA Science Inventory

    This study validates the ecological relevance of estuarine habitat types to the benthic macrofaunal community and, together with previous similar studies, suggests they can serve as elements in ecological periodic tables of benthic macrofaunal usage in the bioregion. We compared...

  6. Benthic macroinvertebrate assemblages in the US nearshore zone of Lake Erie, 2009: Status and linkages to landscape-derived stressors

    EPA Science Inventory

    Benthic macroinvertebrate assemblages have been used as indicators of ecological condition because their responses integrate localized environmental conditions of the sediments and overlying water. Assemblages of benthic invertebrates in the near coastal region are of particular...

  7. Application of Multiple Index Development Approaches to Benthic Invertebrate Data from the Virginian Biogeographic Province (SETAC NA)

    EPA Science Inventory

    Benthic invertebrate indices have commonly been utilized to assess benthic invertebrate communities. These indices have been constructed using different techniques, but have shown different levels of application success. For example, the EMAP Virginian Province Index did not pe...

  8. Benthic phosphorus cycling in the Peruvian oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Lomnitz, Ulrike; Sommer, Stefan; Dale, Andrew W.; Löscher, Carolin R.; Noffke, Anna; Wallmann, Klaus; Hensen, Christian

    2016-03-01

    Oxygen minimum zones (OMZs) that impinge on continental margins favor the release of phosphorus (P) from the sediments to the water column, enhancing primary productivity and the maintenance or expansion of low-oxygen waters. A comprehensive field program in the Peruvian OMZ was undertaken to identify the sources of benthic P at six stations, including the analysis of particles from the water column, surface sediments, and pore fluids, as well as in situ benthic flux measurements. A major fraction of solid-phase P was bound as particulate inorganic P (PIP) both in the water column and in sediments. Sedimentary PIP increased with depth in the sediment at the expense of particulate organic P (POP). The ratio of particulate organic carbon (POC) to POP exceeded the Redfield ratio both in the water column (202 ± 29) and in surface sediments (303 ± 77). However, the POC to total particulate P (TPP = POP + PIP) ratio was close to Redfield in the water column (103 ± 9) and in sediment samples (102 ± 15). This suggests that the relative burial efficiencies of POC and TPP are similar under low-oxygen conditions and that the sediments underlying the anoxic waters on the Peru margin are not depleted in P compared to Redfield. Benthic fluxes of dissolved P were extremely high (up to 1.04 ± 0.31 mmol m-2 d-1), however, showing that a lack of oxygen promotes the intensified release of dissolved P from sediments, whilst preserving the POC / TPP burial ratio. Benthic dissolved P fluxes were always higher than the TPP rain rate to the seabed, which is proposed to be caused by transient P release by bacterial mats that had stored P during previous periods when bottom waters were less reducing. At one station located at the lower rim of the OMZ, dissolved P was taken up by the sediments, indicating ongoing phosphorite formation. This is further supported by decreasing porewater phosphate concentrations with sediment depth, whereas solid-phase P concentrations were comparatively

  9. Analytical characterization of selective benthic flux components in estuarine and coastal waters

    USGS Publications Warehouse

    King, Jeffrey N.

    2011-01-01

    Benthic flux is the rate of flow across the bed of a water body, per unit area of bed. It is forced by component mechanisms, which interact. For example, pressure gradients across the bed, forced by tide, surface gravity waves, density gradients, bed–current interaction, turbulence, and terrestrial hydraulic gradients, drive an advective benthic flux of water and constituents between estuarine and coastal waters, and surficial aquifers. Other mechanisms also force benthic flux, such as chemical gradients, bioturbation, and dispersion. A suite of component mechanisms force a total benthic flux at any given location, where each member of the suite contributes a component benthic flux. Currently, the types and characteristics of component interactions are not fully understood. For example, components may interact linearly or nonlinearly, and the interaction may be constructive or destructive. Benthic flux is a surface water–groundwater interaction process. Its discharge component to a marine water body is referred to, in some literature, as submarine groundwater discharge. Benthic flux is important in characterizing water and constituent budgets of estuarine and coastal systems. Analytical models to characterize selective benthic flux components are reviewed. Specifically, these mechanisms are for the component associated with the groundwater tidal prism, and forced by surface gravity wave setup, surface gravity waves on a plane bed, and the terrestrial hydraulic gradient. Analytical models are applied to the Indian River Lagoon, Florida; Great South Bay, New York; and the South Atlantic Bight in South Carolina and portions of North Carolina.

  10. Turbulence and nutrient interactions that control benthic algal production in an engineered cultivation raceway

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Flow turbulence can be a controlling factor to the growth of benthic algae, but few studies have quantified this relationship in engineered cultivation systems. Experiments were performed to understand the limiting role of turbulence to algal productivity in an algal turf scrubber for benthic algal...

  11. ALLOMETRIC LENGTH-WEIGHT RELATIONSHIPS FOR BENTHIC PREY OF AQUATIC WILDLIFE IN COASTAL MARINE HABITATS

    EPA Science Inventory

    We developed models to estimate the soft tissue content of benthic marine invertebrates that are prey for aquatic wildlife. Allometric regression models of tissue wet weight with shell length for 10 species of benthic invertebrates had r2 values ranging from 0.29 for hermit crabs...

  12. Refinement, validation, and application of a benthic condition index for northern Gulf of Mexico estuaries

    USGS Publications Warehouse

    Engle, V.D.; Summers, J.K.

    1999-01-01

    By applying discriminant analysis to benthic macroinvertebrate data, we have developed an indicator of benthic condition for northern Gulf of Mexico estuaries. The data used were collected by the United States Environmental Protection Agency's Environmental Monitoring and Assessment Program (EMAP) in the Louisianian Province from 1991 to 1994. This benthic index represents a linear combination of the following weighted parameters: the proportion of expected species diversity, the mean abundance of tubificid oligochaetes, the percent of total abundance represented by capitellid polychaetes, the percent of total abundance represented by bivalve mollusks, and the percent of total abundance represented by amphipods. We successfully validated and retrospectively applied the benthic index to all of the benthic data collected by EMAP in the Louisianian Province. This benthic index was also calculated for independent data collected from Pensacola Bay, Florida, in order to demonstrate its flexibility and applicability to different estuarine systems within the same biogeographic region. The benthic index is a useful and valid indicator of estuarine condition that is intended to provide environmental managers with a simple tool for assessing the health of benthic macroinvertebrate communities.

  13. Development of a National-Scale Indicator of Benthic Condition for the National Coastal Condition Assessment.

    EPA Science Inventory

    The US EPA has evaluated the application of a national-scale indicator of estuarine benthic condition for the National Coastal Condition Assessment (NCCA). Historically, in the National Coastal Condition Reports (NCCR I-IV), estuarine benthic condition was assessed by applying m...

  14. The Power of Computer-aided Tomography to Investigate Marine Benthic Communities

    EPA Science Inventory

    Utilization of Computer-aided-Tomography (CT) technology is a powerful tool to investigate benthic communities in aquatic systems. In this presentation, we will attempt to summarize our 15 years of experience in developing specific CT methods and applications to marine benthic co...

  15. A MORE COST-EFFECTIVE EMAP-ESTUARIES BENTHIC MACROFAUNAL SAMPLING PROTOCOL

    EPA Science Inventory

    The standard benthic macrofaunal sampling protocol in the U.S. Environmental Protection Agency's Pacific Coast Environmental Monitoring and Assessment Program (EMAP) is to collect a minimum of 30 random benthic samples per reporting unit (e.g., estuary) using a 0.1 m2 grab and to...

  16. BENTHIC INFAUNAL VARIATION IN GULLMARSFJORD, WESTERN SWEDEN - IS CLIMATE VARIATION A MAJOR FACTOR?

    EPA Science Inventory

    In October 1987, there was extensive mortality of benthic organisms in relatively shallow water areas of the inner part of the Gullmarsfjord on the Swedish west coast, probably caused by low oxygen levels. Benthic disturbance caused by a continuation of hypoxia was also seen in J...

  17. A MORE COST-EFFECTIVE EMAP-W BENTHIC MACROFAUNAL SAMPLE UNIT

    EPA Science Inventory

    The standard EPA West Coast Environmental Monitoring and Assessment Program (EMAP-W) benthic macrofaunal sampling protocol is to collect 30-50 random benthic samples per reporting unit (e.g., estuary, region) using a 0.1 m2 grab and to sort out macrofauna using a 1.0 mm mesh scre...

  18. Benthic control freaks: Effects of the tubiculous amphipod Haploops nirae on the specific diversity and functional structure of benthic communities

    NASA Astrophysics Data System (ADS)

    Rigolet, Carinne; Dubois, Stanislas F.; Thiébaut, Eric

    2014-01-01

    Haploops nirae is a gregarious tubiculous amphipod which extended its habitat over thousands of hectares in shallow waters of South Brittany bays (Bay of Biscay, Atlantic) over the last decades and created uniquely large and dense tube mats. In the bay of Concarneau, we investigated the specific diversity (i.e. species richness and species composition) and the functional structure (using biological traits) of the macrofauna associated with this Haploops community as a comparison with several surrounding soft-sediment communities to determine the effect of this engineer species on ecosystem functions. We showed that the occurrence of Haploops tubes and individuals significantly modifies sediment features (e.g. change in sediment grain size, increase in C and N organic content) but also largely affect species diversity and benthic composition. The species richness was significantly higher in Haploops community but the species assemblage associated with Haploops habitat was very homogeneous compared to the neighboring habitats and unique with 33% of all species exclusively found in this community. Multivariate analysis (dbRDA) revealed that Haploops density was by far the factor explaining the variation in species composition of benthic communities. No differences in species diversity and assemblage were detected in relationship to Haploops density. A biological trait analysis performed on the whole ecosystem (Haploops included) revealed that Haploops largely dominates the functional structure of the Haploops community by its own functional traits. When performed on selected traits of the associated fauna only (Haploops excluded) the functional structure of the Haploops community was characterized by a greatly reduced proportion of small to medium long lived, sensitive to disturbance, free living or burrowing/tube-building filter-feeding species. H. nirae appears to be a bioengineer and a foundation species that largely modifies its hydro-sedimentary features

  19. The influence of reduced light intensity on the response of benthic diatoms to herbicide exposure.

    PubMed

    Wood, Rebecca J; Mitrovic, Simon M; Lim, Richard P; Kefford, Ben J

    2016-09-01

    Herbicide pollution events in aquatic ecosystems often coincide with increased turbidity and reduced light intensity. It is therefore important to determine whether reduced light intensity can influence herbicide toxicity, especially to primary producers such as benthic diatoms. Benthic diatoms collected from 4 rivers were exposed to herbicides in 48 h rapid toxicity tests under high light (100 µmol m(-2)  s(-1) ) and low light (20 µmol m(-2)  s(-1) ) intensities. The effects of 2 herbicides (atrazine and glyphosate) were assessed on 26 freshwater benthic diatom taxa. There was no significant interaction of light and herbicide effects at the community level or on the majority (22 of 26) of benthic diatom taxa. This indicates that low light levels will likely have only a minor influence on the response of benthic diatoms to herbicides. Environ Toxicol Chem 2016;35:2252-2260. © 2016 SETAC.

  20. The influence of reduced light intensity on the response of benthic diatoms to herbicide exposure.

    PubMed

    Wood, Rebecca J; Mitrovic, Simon M; Lim, Richard P; Kefford, Ben J

    2016-09-01

    Herbicide pollution events in aquatic ecosystems often coincide with increased turbidity and reduced light intensity. It is therefore important to determine whether reduced light intensity can influence herbicide toxicity, especially to primary producers such as benthic diatoms. Benthic diatoms collected from 4 rivers were exposed to herbicides in 48 h rapid toxicity tests under high light (100 µmol m(-2)  s(-1) ) and low light (20 µmol m(-2)  s(-1) ) intensities. The effects of 2 herbicides (atrazine and glyphosate) were assessed on 26 freshwater benthic diatom taxa. There was no significant interaction of light and herbicide effects at the community level or on the majority (22 of 26) of benthic diatom taxa. This indicates that low light levels will likely have only a minor influence on the response of benthic diatoms to herbicides. Environ Toxicol Chem 2016;35:2252-2260. © 2016 SETAC. PMID:26801964

  1. One Step forward: Benthic Pelagic Coupling and Indicators for Environmental Status

    PubMed Central

    Dimitriou, Panagiotis D.; Papageorgiou, Nafsika; Arvanitidis, Christos; Assimakopoulou, Georgia; Pagou, Kalliopi; Papadopoulou, Konstantia N.; Pavlidou, Alexandra; Pitta, Paraskevi; Reizopoulou, Sofia; Simboura, Nomiki; Karakassis, Ioannis

    2015-01-01

    A large data set from the Eastern Mediterranean was analyzed to explore the relationship between seawater column variables and benthic community status. Our results showed a strong quantitative link between the seawater column variables (Chlorophyll a and Eutrophication Index) and various indicators describing benthic diversity and community composition. The percentage of benthic opportunistic species increased significantly in the stations with high trophic status of the seawater column and so did the strength of the coupling between values of seawater column and benthic indicators. The Eutrophication Index threshold level of 0.85, separating the “Bad and Poor” from “Moderate to High” conditions could serve as an acceptable critical value above which there is a readily observable change in benthic community composition. PMID:26496714

  2. Bioaccumulation of heavy metals by benthic invertebrates at the Arkansas River, Colorado

    SciTech Connect

    Kiffney, P.M.; Clements, W.H. . Dept. of Fisheries and Wildlife Biology)

    1993-08-01

    A one-year biomonitoring study was conducted to determine the extent of metal contamination (Cd, Cu, and Zn) in a benthic community from the Arkansas River (CO), a subalpine stream impacted by discharges from historic mining operations. Elevated concentrations of metals in water were paralleled by higher concentrations in benthic organisms. Significant differences (p < 0.05) in metal concentrations in aufwuchs and benthic macroinvertebrates among upstream (reference) and downstream stations were observed. Metal concentration in aufwuchs and benthic invertebrates remained elevated at some downstream stations, despite decreases in water concentrations. Time of year and functional group contributed to the variation in metal bioaccumulation in benthic macroinvertebrates. Monitoring metal concentrations in aquatic macroinvertebrates was a better indicator of metal bioavailability in the Arkansas River than ambient (water) metal concentrations.

  3. Riparian shading controls instream spring phytoplankton and benthic algal growth.

    PubMed

    Halliday, S J; Skeffington, R A; Wade, A J; Bowes, M J; Read, D S; Jarvie, H P; Loewenthal, M

    2016-06-15

    Dissolved oxygen (DO) concentrations showed a striking pattern in a multi-year study of the River Enborne, a small river in SE England. In each of three years (2010-2012), maximum DO concentrations were attained in mid-April, preceded by a period of steadily increasing diurnal amplitudes, followed by a steady reduction in both amplitude and concentration. Flow events during the reduction period reduce DO to low concentrations until the following spring. Evidence is presented that this pattern is mainly due to benthic algal growth which is eventually suppressed by the growth of the riparian tree canopy. Nitrate and silicate concentrations are too high to inhibit the growth of either benthic algae or phytoplankton, but phosphate concentrations might have started to reduce growth if the tree canopy development had been delayed. This interpretation is supported by evidence from weekly flow cytometry measurements and analysis of the diurnal, seasonal and annual patterns of nutrient concentrations. As the tree canopy develops, the river switches from an autotrophic to a heterotrophic state. The results support the use of riparian shading to help control algal growth, and highlight the risks of reducing riparian shade.

  4. Riparian shading controls instream spring phytoplankton and benthic algal growth.

    PubMed

    Halliday, S J; Skeffington, R A; Wade, A J; Bowes, M J; Read, D S; Jarvie, H P; Loewenthal, M

    2016-06-15

    Dissolved oxygen (DO) concentrations showed a striking pattern in a multi-year study of the River Enborne, a small river in SE England. In each of three years (2010-2012), maximum DO concentrations were attained in mid-April, preceded by a period of steadily increasing diurnal amplitudes, followed by a steady reduction in both amplitude and concentration. Flow events during the reduction period reduce DO to low concentrations until the following spring. Evidence is presented that this pattern is mainly due to benthic algal growth which is eventually suppressed by the growth of the riparian tree canopy. Nitrate and silicate concentrations are too high to inhibit the growth of either benthic algae or phytoplankton, but phosphate concentrations might have started to reduce growth if the tree canopy development had been delayed. This interpretation is supported by evidence from weekly flow cytometry measurements and analysis of the diurnal, seasonal and annual patterns of nutrient concentrations. As the tree canopy develops, the river switches from an autotrophic to a heterotrophic state. The results support the use of riparian shading to help control algal growth, and highlight the risks of reducing riparian shade. PMID:27192431

  5. An apparatus for preparing benthic samples aboard ship

    USGS Publications Warehouse

    Pepper, Phillip N.; Girard, Thomas L.; Stapanian, Martin A.

    2001-01-01

    We describe a safe and effective apparatus for washing and reducing the volume of benthic samples collected by grab samplers aboard ship. The sample is transferred directly from the dredge to the apparatus and then washed with water pumped through pipes in the apparatus and from onboard hoses. Wastewater and materials smaller than 0.541 mm in diameter are washed overboard. Larger materials, including benthic organisms, collect on an upper 0.64-cm screen and on a lower 30-mm-mesh stainless steel bolt cloth. A collection jar is screwed into the bottom of the apparatus. Therefore, transfer of sample material from the apparatus to the jar is quick and easy. This apparatus has several advantages for use aboard ship over others described in the literature, especially in rough seas, in cold weather, and at night. The apparatus provides a safe and convenient platform for washing and reducing samples, and samples can be prepared while the vessel is traveling at full speed.

  6. Spatial dynamics of benthic competition on coral reefs.

    PubMed

    Sandin, Stuart A; McNamara, Dylan E

    2012-04-01

    The community structure of sedentary organisms is largely controlled by the outcome of direct competition for space. Understanding factors defining competitive outcomes among neighbors is thus critical for predicting large-scale changes, such as transitions to alternate states within coral reefs. Using a spatially explicit model, we explored the importance of variation in two spatial properties in benthic dynamics on coral reefs: (1) patterns of herbivory are spatially distinct between fishes and sea urchins and (2) there is wide variation in the areal extent into which different coral species can expand. We reveal that the size-specific, competitive asymmetry of corals versus fleshy algae highlights the significance of spatial patterning of herbivory and of coral growth. Spatial dynamics that alter the demographic importance of coral recruitment and maturation have profound effects on the emergent structure of the reef benthic community. Spatially constrained herbivory (as by sea urchins) is more effective than spatially unconstrained herbivory (as by many fish) at opening space for the time needed for corals to settle and to recruit to the adult population. Further, spatially unconstrained coral growth (as by many branching coral species) reduces the number of recruitment events needed to fill a habitat with coral relative to more spatially constrained growth (as by many massive species). Our model predicts that widespread mortality of branching corals (e.g., Acropora spp) and herbivorous sea urchins (particularly Diadema antillarum) in the Caribbean has greatly reduced the potential for restoration across the region. PMID:22009340

  7. Mapping coral reef benthic cover with fused IKONOS imagery

    NASA Astrophysics Data System (ADS)

    Wang, Yuanyuan; Chen, Yunhao; Li, Jing

    2007-06-01

    In this article, we present some experiments on coral reef benthic cover mapping with fused IKONOS image. The objective of our study is to establish an efficient approach for the classification task on hand. Four scenarios are designed and in each scenario two classification methods (Maximum Likelihood and Decision Tree) are implemented. Ground truth data is obtained through visual interpretation and manual digitization, against which accuracy of classification map is calculated. Results indicate that mining spectral information deeply (scenario III and IV) can increase classification accuracy dramatically. Compared with conventional utilization of spectral data (scenarioI), classification accuracy of ML and DT respectively increases by 3.94% and 5.15% under scenario IV. However, when spectral and spatial information is combined together (scenario II), accuracy of ML and DT is respectively reduced by 8.02% and 2.31%. It can be concluded from our study that when classify benthic cover with high-resolution remote sensing data in pixel-based pattern, utilization of spatial information should not be excessively emphasized. Fully exploiting spectral information may bring more benefits. Moreover, DT is more robust and can produce more accurate classification results than ML. Our results help scientists and managers in applying IKONOS-class data for coral reef mapping applications.

  8. Measuring coral reef community metabolism using new benthic chamber technology

    USGS Publications Warehouse

    Yates, K.K.; Halley, R.B.

    2003-01-01

    Accurate measurement of coral reef community metabolism is a necessity for process monitoring and in situ experimentation on coral reef health. Traditional methodologies used for these measurements are effective but limited by location and scale constraints. We present field trial results for a new benthic chamber system called the Submersible Habitat for Analyzing Reef Quality (SHARQ). This large, portable incubation system enables in situ measurement and experimentation on community- scale metabolism. Rates of photosynthesis, respiration, and calcification were measured using the SHARQ for a variety of coral reef substrate types on the reef flat of South Molokai, Hawaii, and in Biscayne National Park, Florida. Values for daily gross production, 24-h respiration, and net calcification ranged from 0.26 to 6.45 g O2 m-2 day-1, 1.96 to 8.10 g O2 m-2 24 h-1, and 0.02 to 2.0 g CaCO3 m -2 day-1, respectively, for all substrate types. Field trials indicate that the SHARQ incubation chamber is an effective tool for in situ isolation of a water mass over a variety of benthic substrate types for process monitoring, experimentation, and other applications.

  9. Predicting the Presence of Large Fish through Benthic Geomorphic Features

    NASA Astrophysics Data System (ADS)

    Knuth, F.; Sautter, L.; Levine, N. S.; Kracker, L.

    2013-12-01

    Marine Protected Areas are critical in sustaining the resilience of fish populations to commercial fishing operations. Using acoustic data to survey these areas promises efficiency, accuracy, and minimal environmental impact. In July, 2013, the NOAA Ship Pisces collected bathymetric, backscatter and water column data for 10 proposed MPA sites along the U.S. Southeast Atlantic continental shelf. A total of 205 km2 of seafloor were mapped between Mayport, FL and Wilmington, NC, using the SIMRAD ME70 and EK60 echosounder systems. These data were processed in Caris HIPS, QPS FMGT, MATLAB and ArcGIS. The backscatter and bathymetry reveal various benthic geomorphic features, including flat sand, rippled sand, and rugose hard bottom. Water column data directly above highly rugose hardbottom contains the greatest counts for large fish populations. Using spatial statistics, such as a geographically weighted regression model, we aim to identify features of the benthic profile, including rugosity, curvature and slope, that can predict the presence of large fish. The success of this approach will greatly expedite fishery surveys, minimize operational cost and aid in making timely management decisions.

  10. Compound-Specific Amino Acid Isotopic Analysis of Benthic Food Webs in the Chukchi Sea

    NASA Astrophysics Data System (ADS)

    Zhang, M.; Cooper, L. W.; Biasatti, D. M.; Grebmeier, J. M.

    2014-12-01

    The Chukchi Sea is known for locally high standing stocks of benthic macrofauna and strong coupling between pelagic-benthic components of the ecosystem. However, benthic food structure is not fully understood, due to varied sources of particulate organic matter (POM) and the high diversity of benthic invertebrates. We provide the first demonstration of the application of compound-specific amino acid isotope analysis to study the dietary sources and trophic structure for this Arctic marginal sea. About 20 stations in Chukchi Sea were sampled during cruises in August of 2012 and 2013. At each station, phytoplankton, POM and benthic fauna were collected, processed and analyzed using GC-C-IRMS (gas chromatography-combustion-isotope ratio mass spectrometry). Among benthic fauna, dominant species included the following taxonomic groups: Ophiuroidea, Amphipoda, Polychaeta, Gastropoda, Bivalvia, and Cnidaria. The benthic fauna showed similar patterns of individual amino acid δ13C, with glycine the most enriched in 13C and leucine the most depleted in 13C. Specific amino acids including phenylalanine showed spatial variability in δ13C and δ15N values within the sampled area, indicating contributions of different dietary sources including phytoplankton, sea ice algae, benthic algae and terrestrial organic materials. δ15N values of individual amino acids such as the difference between glutamic acid and phenylalanine, i.e. Δ15Nglu-phe (δ15Nglu - δ15Nphe), were also used to identify trophic levels of benthic invertebrates relative to estimates available from bulk δ15N values. These data will ultimately be used to evaluate the spatial variability of organic carbon sources and trophic level interactions of dominant benthic species in the Chukchi Sea.

  11. The mismatch between bioaccumulation in field and laboratory environments: Interpreting the differences for metals in benthic bivalves.

    PubMed

    Belzunce-Segarra, Maria J; Simpson, Stuart L; Amato, Elvio D; Spadaro, David A; Hamilton, Ian L; Jarolimek, Chad V; Jolley, Dianne F

    2015-09-01

    Laboratory-based bioaccumulation and toxicity bioassays are frequently used to predict the ecological risk of contaminated sediments in the field. This study investigates the bioassay conditions most relevant to achieving environmentally relevant field exposures. An identical series of metal-contaminated marine sediments were deployed in the field and laboratory over 31 days. Changes in metal concentrations and partitioning in both sediments and waters were used to interpret differences in metal exposure and bioaccumulation to the benthic bivalve Tellina deltoidalis. Loss of resuspended sediments and deposition of suspended particulate matter from the overlying water resulted in the concentrations of Cu, Pb and Zn (major contaminants) becoming lower in the 1-cm surface layer of field-deployed sediments. Lower exchange rates of overlying waters in the laboratory resulted in higher dissolved metal exposures. The prediction of metal bioaccumulation by the bivalves in field and laboratory was improved by considering the metal partitioning within the surface sediments.

  12. Polar Layers

    NASA Technical Reports Server (NTRS)

    2005-01-01

    12 August 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows a slope upon which are exposed some of the layered materials that underlie the south polar cap of Mars. The layers are generally considered to be sediments--perhaps dust--that may have been cemented by water ice.

    Location near: 84.1oS, 343.9oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

  13. Environmental influences on living marine stromatolites: insights from benthic microalgal communities.

    PubMed

    Rishworth, Gavin M; van Elden, Sean; Perissinotto, Renzo; Miranda, Nelson A F; Steyn, Paul-Pierre; Bornman, Thomas G

    2016-02-01

    Extant marine stromatolites act as partial analogues of their Achaean counterparts, but are rare due to depleted ocean calcium carbonate levels and suppression by eukaryotic organisms. Unique, peritidal tufa stromatolites at the interface between marine and freshwater inputs were discovered in South Africa in the past decade. Our aim was to investigate the benthic microalgal community (green algae, diatoms and cyanobacteria) of these stromatolites to assess succession and dominance patterns using real-time, in situ measurements of algal concentrations and composition. These biological measurements were modelled using generalized linear modelling (GLM) multivariate statistics against water physical and chemical parameters measured at regular monthly intervals, from January to December 2014. Salinity peaked and temperature dipped in winter, with both correlated to microalgal community change (GLM: P < 0.01). Diatoms and cyanobacteria, which construct the stromatolites, were consistently the dominant groups within the algal community, with minimal green algae present throughout the year. Importantly, this demonstrates a unique, relatively stable microalgal stromatolite community as opposed to those of other marine stromatolites, which likely require seasonal and stochastic disturbance to persist. This has implications in terms of interpreting community succession and differential layering in modern and fossilized stromatolites respectively.

  14. Stable-isotope analysis of a deep-sea benthic-fish assemblage: evidence of an enriched benthic food web.

    PubMed

    Boyle, M D; Ebert, D A; Cailliet, G M

    2012-04-01

    In this study, fishes and invertebrates collected from the continental slope (1000 m) of the eastern North Pacific Ocean were analysed using stable-isotope analysis (SIA). Resulting trophic positions (T(P) ) were compared to known diets and habitats from the literature. Dual isotope plots indicated that most species groups (invertebrates and fishes) sorted as expected along the carbon and nitrogen axes, with less intraspecific variability than interspecific variability. Results also indicated an isotopically distinct benthic and pelagic food web, as the benthic food web was more enriched in both nitrogen and carbon isotopes. Trophic positions from SIA supported this finding, resulting in the assignment of fishes to different trophic positions from those expected based on published dietary information. These differences can be explained largely by the habitat of the prey and the percentage of the diet that was scavenged. A mixing model estimated dietary contributions of prey similar to those of the known diet of Bathyraja trachura from stomach-content analysis (SCA). Linear regressions indicated that trophic positions calculated from SIA and SCA, when plotted against B. trachura total length for 32 individuals, exhibited similar variation and patterns. Only the T(P) from SCA yielded significant results (stomach content: P < 0·05, stable isotope: P > 0·05). PMID:22497394

  15. Stable-isotope analysis of a deep-sea benthic-fish assemblage: evidence of an enriched benthic food web.

    PubMed

    Boyle, M D; Ebert, D A; Cailliet, G M

    2012-04-01

    In this study, fishes and invertebrates collected from the continental slope (1000 m) of the eastern North Pacific Ocean were analysed using stable-isotope analysis (SIA). Resulting trophic positions (T(P) ) were compared to known diets and habitats from the literature. Dual isotope plots indicated that most species groups (invertebrates and fishes) sorted as expected along the carbon and nitrogen axes, with less intraspecific variability than interspecific variability. Results also indicated an isotopically distinct benthic and pelagic food web, as the benthic food web was more enriched in both nitrogen and carbon isotopes. Trophic positions from SIA supported this finding, resulting in the assignment of fishes to different trophic positions from those expected based on published dietary information. These differences can be explained largely by the habitat of the prey and the percentage of the diet that was scavenged. A mixing model estimated dietary contributions of prey similar to those of the known diet of Bathyraja trachura from stomach-content analysis (SCA). Linear regressions indicated that trophic positions calculated from SIA and SCA, when plotted against B. trachura total length for 32 individuals, exhibited similar variation and patterns. Only the T(P) from SCA yielded significant results (stomach content: P < 0·05, stable isotope: P > 0·05).

  16. Using Benthic Macroinvertebrate and Fish Communities as Bioindicators of the Tanshui River Basin Around the Greater Taipei Area — Multivariate Analysis of Spatial Variation Related to Levels of Water Pollution

    PubMed Central

    Young, Shuh-Sen; Yang, Hsi-Nan; Huang, Da-Ji; Liu, Su-Miao; Huang, Yueh-Han; Chiang, Chung-Ting; Liu, Jin-Wei

    2014-01-01

    After decades of strict pollution control and municipal sewage treatment, the water quality of the Tanshui River increased significantly after pollution mitigation as indicated by the River Pollution Index (RPI). The pollution level of the estuarine region decreased from severe pollution to mostly moderately impaired. The most polluted waters are presently restricted to a flow track length between 15–35 km relative to the river mouth. From July 2011 to September 2012, four surveys of fish and benthic macroinvertebrates were conducted at 45 sampling sites around the Tanshui River basin. The pollution level of all the study area indicated by the RPI could also be explained by the Family Biotic Index (FBI) and Biotic Index (BI) from the benthic macroinvertebrate community, and the Index of Biotic Integrity (IBI) of the fish community. The result of canonical correlation analysis between aquatic environmental factors and community structure indicated that the community structure was closely related to the level of water pollution. Fish species richness in the estuarine area has increased significantly in recent years. Some catadromous fish and crustaceans could cross the moderate polluted water into the upstream freshwater, and have re-colonized their populations. The benthic macroinvertebrate community relying on the benthic substrate of the estuarine region is still very poor, and the water layer was still moderately polluted. PMID:25026081

  17. Using benthic macroinvertebrate and fish communities as bioindicators of the Tanshui River basin around the greater Taipei area - multivariate analysis of spatial variation related to levels of water pollution.

    PubMed

    Young, Shuh-Sen; Yang, Hsi-Nan; Huang, Da-Ji; Liu, Su-Miao; Huang, Yueh-Han; Chiang, Chung-Ting; Liu, Jin-Wei

    2014-07-14

    After decades of strict pollution control and municipal sewage treatment, the water quality of the Tanshui River increased significantly after pollution mitigation as indicated by the River Pollution Index (RPI). The pollution level of the estuarine region decreased from severe pollution to mostly moderately impaired. The most polluted waters are presently restricted to a flow track length between 15-35 km relative to the river mouth. From July 2011 to September 2012, four surveys of fish and benthic macroinvertebrates were conducted at 45 sampling sites around the Tanshui River basin. The pollution level of all the study area indicated by the RPI could also be explained by the Family Biotic Index (FBI) and Biotic Index (BI) from the benthic macroinvertebrate community, and the Index of Biotic Integrity (IBI) of the fish community. The result of canonical correlation analysis between aquatic environmental factors and community structure indicated that the community structure was closely related to the level of water pollution. Fish species richness in the estuarine area has increased significantly in recent years. Some catadromous fish and crustaceans could cross the moderate polluted water into the upstream freshwater, and have re-colonized their populations. The benthic macroinvertebrate community relying on the benthic substrate of the estuarine region is still very poor, and the water layer was still moderately polluted.

  18. Benthic foraminifera at the Paleocene/Eocene thermal maximum in the western Tethys (Forada section): variability in climate and productivity

    NASA Astrophysics Data System (ADS)

    Giusberti, L.; Boscolo Galazzo, F.; Thomas, E.

    2015-09-01

    The Forada section (northeastern Italy) provides a continuous, expanded deep-sea record of the Paleocene/Eocene thermal maximum (PETM) in the central-western Tethys. We combine a new, high resolution, benthic foraminiferal assemblage record with published calcareous plankton, mineralogical and biomarker data to document climatic and environmental changes across the PETM, highlighting the benthic foraminiferal extinction event (BEE). The onset of the PETM, occurring ~ 30 kyr after a precursor event, is marked by a thin, black, barren clay layer, possibly representing a brief pulse of anoxia and carbonate dissolution. The BEE occurred within the 10 cm interval including this layer. During the first 3.5 kyr of the PETM several agglutinated recolonizing taxa show rapid species turnover, indicating a highly unstable, CaCO3-corrosive environment. Calcareous taxa reappeared after this interval, and the next ~ 9 kyr were characterized by rapid alternation of peaks in abundance of various calcareous and agglutinant recolonizers. These observations suggest that synergistic stressors including deep water CaCO3-corrosiveness, low oxygenation, and high environmental instability caused the extinction. Combined faunal and biomarker data (BIT index, higher plant n-alkane average chain length) and the high abundance of the mineral chlorite suggest that erosion and weathering increased strongly at the onset of the PETM, due to an overall wet climate with invigorated hydrological cycle, which led to storm flood-events carrying massive sediment discharge into the Belluno Basin. This interval was followed by the core of the PETM, characterized by four precessionally paced cycles in CaCO3%, hematite%, δ13C, abundant occurrence of opportunistic benthic foraminiferal taxa, as well as calcareous nannofossil and planktonic foraminiferal taxa typical of high productivity environments, radiolarians, and lower δDn-alkanes. We interpret these cycles as reflecting alternation between an

  19. Layered materials

    NASA Astrophysics Data System (ADS)

    Johnson, David; Clarke, Simon; Wiley, John; Koumoto, Kunihito

    2014-06-01

    Layered compounds, materials with a large anisotropy to their bonding, electrical and/or magnetic properties, have been important in the development of solid state chemistry, physics and engineering applications. Layered materials were the initial test bed where chemists developed intercalation chemistry that evolved into the field of topochemical reactions where researchers are able to perform sequential steps to arrive at kinetically stable products that cannot be directly prepared by other approaches. Physicists have used layered compounds to discover and understand novel phenomena made more apparent through reduced dimensionality. The discovery of charge and spin density waves and more recently the remarkable discovery in condensed matter physics of the two-dimensional topological insulating state were discovered in two-dimensional materials. The understanding developed in two-dimensional materials enabled subsequent extension of these and other phenomena into three-dimensional materials. Layered compounds have also been used in many technologies as engineers and scientists used their unique properties to solve challenging technical problems (low temperature ion conduction for batteries, easy shear planes for lubrication in vacuum, edge decorated catalyst sites for catalytic removal of sulfur from oil, etc). The articles that are published in this issue provide an excellent overview of the spectrum of activities that are being pursued, as well as an introduction to some of the most established achievements in the field. Clusters of papers discussing thermoelectric properties, electronic structure and transport properties, growth of single two-dimensional layers, intercalation and more extensive topochemical reactions and the interleaving of two structures to form new materials highlight the breadth of current research in this area. These papers will hopefully serve as a useful guideline for the interested reader to different important aspects in this field and

  20. Isotopic Constraints on Sources and Benthic Turnover at Mound 12, Western Costa Rican Margin

    NASA Astrophysics Data System (ADS)

    Rehder, G.; Mau, S.; Linke, P.; Stange, K.

    2004-12-01

    During several expeditions, we investigated the emission and isotopic signature of methane at several mounds of the western continental margin off Costa Rica and Nicaragua. All of the mounds investigated, either created by mud volcanism or mud diapirism, show indications of fluid venting, including authigenic carbonates, chemoautotrophic consortia, salt depleted pore waters, and methane plumes in the water column. However, the amount of methane released as well as the stable carbon isotopic ratio (del C-13) vary considerably. Here we report on results from Mound 12, a mound with a very weak morphological expression; that is only 30 m high and elongated in northeast-southwest direction with diameters of about 1 to 1.6 km. Data were gathered using standard CTD/rosette equipment, a bottom water sampler enabling to resolve the methane distribution within the lowermost meter of the water column, a benthic chamber lander (BCL), multicorer and piston corer deployments. Data show a very light biogenic methane source (del C-13 < -90 permil within the sediments), -76 permil in the lowermost water samples with concentrations up to 100 nmo/L, and a methane background of - 45 permil 20 m above the vent site. High oxygen demand immediately at a site with bacterial mats in connection to lower carbon stable isotopic ratios with increasing sediment depth is in contrast to low oxygen demand and heavier stable isotopic ratios with increasing sediment depth only one meter apart. Moreover, the relation of methane concentration vs. isotopic signature above the vent sites implies considerable oxidation and fractionation in the benthic boundary layer (BBL) above the vent site, which is supported by some biomarker investigations at the same site. Significant oxidation of methane above vent sites within the BBL has not been reported so far. An alternative explanation, which is the existence of an additional methane source with an isotopic signature similar to the background ( del C-13 =-45

  1. Modelling Changes of the Paleogene Ca Budget Using Benthic Foraminifera

    NASA Astrophysics Data System (ADS)

    Pabich, S.; Gussone, N. C.; Vollmer, C.; Palike, H.; Rabe, K.; Teichert, B. M.

    2014-12-01

    Understanding the earth's climate as well as the oceanic chemical and isotopic evolution in the past is one of the main aims in earth science. Ca as one of the major elements in the ocean is especially important. Its variation in concentration are controlled by different factors including the CO2 concentration of the atmosphere, continental weathering and Ca carbonate sedimentation. We used samples from IODP Exp. 320/321 to establish a δ44/40Ca paleo-seawater record between 45 and 25 Ma and model changes in the Ca budget through time. Our results show differences in the Eocene and Oligocene Ca isotope record of benthic foraminifers. The δ44/40Ca values during the Eocene are relatively constant with no significant fluctuations during phases of large short term CCD fluctuations[1]. The Oligocene is characterized by sediments with uniformly high carbonate content and increasing δ44/40Ca towards the late Oligocene. Past seawater δ44/40Ca values (Fig. 1) were calculated from the measured benthic foraminifer record applying the calibration for Gyroidinoides spp.[2]. The Ca budget during the Eocene is relatively constant and not affected by short term CCD fluctuations, indicating that they are too small to alter the isotopic Ca budget. The Oligocene, in contrast is characterized by a general increase in δ44/40Ca seawater values and a continuously deep CCD[1]. This is consistent with a massive long term (>1Ma) CaCO3 deposition and decreasing Ca concentration in the ocean water. To examine the preservation (dissolution and recrystallization) of the foraminifer test through time, we studied additionally the changes in the crystallographic orientations trough time by Electron Backscatter Diffraction (EBSD) analysis and Raman spectroscopy. As a final step we use our δ44/40Ca seawater record to run a combined Ca and C model showing the effect of Ca weathering input, carbonate remobilization and dolomitization on the Ca and carbonate system of seawater [1]. [1]Pälike H

  2. Benthic nitrogen cycling traversing the capitalize peruvian oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Bohlen, L.; Dale, A. W.; Sommer, S.; Mosch, T.; Hensen, C.; Noffke, A.; Scholz, F.; Wallmann, K.

    2011-10-01

    Benthic nitrogen (N) cycling was investigated at six stations along a transect traversing the Peruvian oxygen minimum zone (OMZ) at 11°S. An extensive dataset including porewater concentration profiles and in situ benthic fluxes of nitrate (NO 3-), nitrite (NO 2-) and ammonium (NH 4+) was used to constrain a 1-D reaction-transport model designed to simulate and interpret the measured data at each station. Simulated rates of nitrification, denitrification, anammox and dissimilatory nitrate reduction to ammonium (DNRA) by filamentous large sulfur bacteria (e.g. Beggiatoa and Thioploca) were highly variable throughout the OMZ yet clear trends were discernible. On the shelf and upper slope (80-260 m water depth) where extensive areas of bacterial mats were present, DNRA dominated total N turnover (⩽2.9 mmol N m -2 d -1) and accounted for ⩾65% of NO 3- + NO 2- uptake by the sediments from the bottom water. Nonetheless, these sediments did not represent a major sink for dissolved inorganic nitrogen (DIN = NO 3- + NO 2- + NH 4+) since DNRA reduces NO 3- and, potentially NO 2-, to NH 4+. Consequently, the shelf and upper slope sediments were recycling sites for DIN due to relatively low rates of denitrification and high rates of ammonium release from DNRA and ammonification of organic matter. This finding contrasts with the current opinion that sediments underlying OMZs are a strong sink for DIN. Only at greater water depths (300-1000 m) did the sediments become a net sink for DIN. Here, denitrification was the major process (⩽2 mmol N m -2 d -1) and removed 55-73% of NO 3- and NO 2- taken up by the sediments, with DNRA and anammox accounting for the remaining fraction. Anammox was of minor importance on the shelf and upper slope yet contributed up to 62% to total N 2 production at the 1000 m station. The results indicate that the partitioning of oxidized N (NO 3-, NO 2-) into DNRA or denitrification is a key factor determining the role of marine sediments as DIN

  3. Benthic buffers and boosters of ocean acidification on coral reefs

    NASA Astrophysics Data System (ADS)

    Anthony, K. R. N.; Diaz-Pulido, G.; Verlinden, N.; Tilbrook, B.; Andersson, A. J.

    2013-07-01

    Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (NCP) and calcification (NCC). Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to changes in the seawater aragonite saturation state (Ωa). Results of flume studies using intact reef habitats (1.2 m by 0.4 m), showed a hierarchy of responses across groups, depending on CO2 level, time of day and water flow. At low CO2 (350-450 μatm), macroalgae (Chnoospora implexa), turfs and sand elevated Ωa of the flume water by around 0.10 to 1.20 h-1 - normalised to contributions from 1 m2 of benthos to a 1 m deep water column. The rate of Ωa increase in these groups was doubled under acidification (560-700 μatm) and high flow (35 compared to 8 cm s-1). In contrast, branching corals (Acropora aspera) increased Ωa by 0.25 h-1 at ambient CO2 (350-450 μatm) during the day, but reduced Ωa under acidification and high flow. Nighttime changes in Ωa by corals were highly negative (0.6-0.8 h-1) and exacerbated by acidification. Calcifying macroalgae (Halimeda spp.) raised Ωa by day (by around 0.13 h-1), but lowered Ωa by a similar or higher amount at night. Analyses of carbon flux contributions from benthic communities with four different compositions to the reef water carbon chemistry across Heron Reef flat and lagoon indicated that the net lowering of Ωa by coral-dominated areas can to some extent be countered by long water-residence times in neighbouring areas dominated by turfs, macroalgae and carbonate sand.

  4. Ecological periodic tables for benthic macrofaunal usage of estuarine habitats in the US Pacific Northwest

    NASA Astrophysics Data System (ADS)

    Ferraro, Steven P.; Cole, Faith A.

    2011-07-01

    This study shows that spatially and temporally recurring benthic macrofauna-habitat patterns validate the ecological relevance of habitat types to benthic macrofauna and suggest they can serve as elements in ecological periodic tables of benthic macrofaunal usage. We discovered patterns across nine habitat types (intertidal eelgrass [ Zostera marina], dwarf eelgrass [ Zostera japonica], oyster [ Crassostrea gigas] ground culture, burrowing mud shrimp [ Upogebia pugettensis], burrowing ghost shrimp [ Neotrypaea californiensis], shell, sand, mud, and subtidal) on a variety of benthic macrofaunal community state variables in Grays Harbor, Washington, USA and compared them to those in Willapa Bay, Washington, USA. There were nominal differences in benthic macrofaunal Bray-Curtis similarity between all the habitats investigated except eelgrass and oyster in both estuaries. Across-habitat patterns on mean benthic macrofaunal species richness, abundance, biomass, abundance of deposit, suspension and facultative feeders, a dominance and a diversity index for the five habitats common to both studies were the same on a rank measurement scale: eelgrass ≈ oyster > mud shrimp > ghost shrimp ≈ subtidal. The patterns for most of the habitats and benthic macrofaunal measures were the same on a ratio measurement scale.

  5. Environmental Drivers of Benthic Flux Variation and Ecosystem Functioning in Salish Sea and Northeast Pacific Sediments.

    PubMed

    Belley, Rénald; Snelgrove, Paul V R; Archambault, Philippe; Juniper, S Kim

    2016-01-01

    The upwelling of deep waters from the oxygen minimum zone in the Northeast Pacific from the continental slope to the shelf and into the Salish Sea during spring and summer offers a unique opportunity to study ecosystem functioning in the form of benthic fluxes along natural gradients. Using the ROV ROPOS we collected sediment cores from 10 sites in May and July 2011, and September 2013 to perform shipboard incubations and flux measurements. Specifically, we measured benthic fluxes of oxygen and nutrients to evaluate potential environmental drivers of benthic flux variation and ecosystem functioning along natural gradients of temperature and bottom water dissolved oxygen concentrations. The range of temperature and dissolved oxygen encountered across our study sites allowed us to apply a suite of multivariate analyses rarely used in flux studies to identify bottom water temperature as the primary environmental driver of benthic flux variation and organic matter remineralization. Redundancy analysis revealed that bottom water characteristics (temperature and dissolved oxygen), quality of organic matter (chl a:phaeo and C:N ratios) and sediment characteristics (mean grain size and porosity) explained 51.5% of benthic flux variation. Multivariate analyses identified significant spatial and temporal variation in benthic fluxes, demonstrating key differences between the Northeast Pacific and Salish Sea. Moreover, Northeast Pacific slope fluxes were generally lower than shelf fluxes. Spatial and temporal variation in benthic fluxes in the Salish Sea were driven primarily by differences in temperature and quality of organic matter on the seafloor following phytoplankton blooms. These results demonstrate the utility of multivariate approaches in differentiating among potential drivers of seafloor ecosystem functioning, and indicate that current and future predictive models of organic matter remineralization and ecosystem functioning of soft-muddy shelf and slope seafloor

  6. Antarctic Benthic Fauna in the Global Climate Change

    NASA Astrophysics Data System (ADS)

    Kidawa, Anna; Janecki, Tomasz

    2011-01-01

    In the last 50 years a significant climatic shift has been observed along the Antarctic Peninsula (air and seawater temperature rise, glacial retreat, localized instances of lowered shallow waters salinities). Many Antarctic marine benthic invertebrates are adapted to specific environmental conditions (e.g. low stable temperatures, high salinity and oxygen content). Changes caused by global climate changes and subsequent glacial melting can be expected to have significant impacts on species physiology and distribution. The rise of sea water temperature coupled with such additional stress factors as melt water run-off, increased ice disturbance, disruption of food webs or invasion of alien species can be a serious problem for their long-term survival.

  7. Effect of exposure method on benthic organism responses

    SciTech Connect

    Rowland, C.; Burton, G.A. Jr.

    1995-12-31

    Organism response to non-polar organics and inorganic contaminants is affected by the route and method of exposure. Little data exists, however, on the effect of different exposures on freshwater benthic and epibenthic organisms. The amphipod, Hyalella azteca and the oligochaete, Lumbriculus variegatus were exposed to contaminated sediments and overlying waters in the laboratory using traditional static-renewal exposure systems as well as in situ using different exposure chamber designs. Laboratory and field exposures were compared, focusing on survival and tissue residues of polycyclic aromatic hydrocarbons (PAHs). Responses of test organisms were compared also to indigenous species. Results showed that laboratory and in situ exposures differ frequently, but optimal exposure systems are possible which reduce uncertainty in risk or hazard assessments that predict toxicity or bioaccumulation.

  8. The physics of broadcast spawning in benthic invertebrates.

    PubMed

    Crimaldi, John P; Zimmer, Richard K

    2014-01-01

    Most benthic invertebrates broadcast their gametes into the sea, whereupon successful fertilization relies on the complex interaction between the physics of the surrounding fluid flow and the biological properties and behavior of eggs and sperm. We present a holistic overview of the impact of instantaneous flow processes on fertilization across a range of scales. At large scales, transport and stirring by the flow control the distribution of gametes. Although mean dilution of gametes by turbulence is deleterious to fertilization, a variety of instantaneous flow phenomena can aggregate gametes before dilution occurs. We argue that these instantaneous flow processes are key to fertilization efficiency. At small scales, sperm motility and taxis enhance contact rates between sperm and chemoattractant-releasing eggs. We argue that sperm motility is a biological adaptation that replaces molecular diffusion in conventional mixing processes and enables gametes to bridge the gap that remains after aggregation by the flow.

  9. Knowledge of Brazilian benthic marine fauna throughout time.

    PubMed

    Longo, Leila de Lourdes; Amado Filho, Gilberto Menezes

    2014-01-01

    The ecosystems of Brazil's continental shelf and oceanic islands comprise a variety of environments that display unique geomorphological and geophysical features and biotic components. The quest to attain knowledge of Brazilian marine fauna is hampered by coastline length, biodiversity, a high rate of endemism, and a shortage of specialized researchers. Based on a systematic bibliographic review, the article offers an overview of the history, current knowledge, and outlook for the field of marine biodiversity in Brazil. Our findings show that government initiatives have afforded greater knowledge of Brazilian marine fauna species and opened new perspectives, including reliance on complex tools to describe benthic marine habitats in terms of their geological, geophysical, and biotic composition.

  10. Selective responses of benthic foraminifera to thermal pollution.

    PubMed

    Titelboim, Danna; Almogi-Labin, Ahuva; Herut, Barak; Kucera, Michal; Schmidt, Christiane; Hyams-Kaphzan, Orit; Ovadia, Ofer; Abramovich, Sigal

    2016-04-15

    Persistent thermohaline pollution at a site along the northern coast of Israel, due to power and desalination plants, is used as a natural laboratory to evaluate the effects of rising temperature and salinity levels on benthic foraminifera living in shallow hard-bottom habitats. Biomonitoring of the disturbed area and a control station shows that elevated temperature is a more significant stressor compared to salinity, thus causing a decrease in abundance and richness. Critical temperature thresholds were observed at 30 and 35°C, the latter representing the most thermally tolerant species in the studied area Pararotalia calcariformata, which is the only symbiont-bearing species observed within the core of the heated area. Common species of the shallow hard-bottom habitats including several Lessepsian invaders are almost absent in the most exposed site indicating that excess warming will likely impede the survival of these species that currently benefit from the ongoing warming of the Eastern Mediterranean.

  11. Methods applied in studies of benthic marine debris.

    PubMed

    Spengler, Angela; Costa, Monica F

    2008-02-01

    The ocean floor is one of the main accumulation sites of marine debris. The study of this kind of debris still lags behind that of shorelines. It is necessary to identify the methods used to evaluate this debris and how the results are presented and interpreted. From the available literature on benthic marine debris (26 studies), six sampling methods were registered: bottom trawl net, sonar, submersible, snorkeling, scuba diving and manta tow. The most frequent method used was bottom trawl net, followed by the three methods of diving. The majority of the debris was classified according to their former use and the results usually expressed as items per unity of area. To facilitate comparisons of the contamination levels among sites and regions some standardization requirements are suggested.

  12. Geologic characteristics of benthic habitats in Glacier Bay, southeast Alaska

    USGS Publications Warehouse

    Harney, Jodi N.; Cochrane, Guy R.; Etherington, Lisa L.; Dartnell, Pete; Golden, Nadine E.; Chezar, Hank

    2006-01-01

    In April 2004, more than 40 hours of georeferenced submarine digital video was collected in water depths of 15-370 m in Glacier Bay to (1) ground-truth existing geophysical data (bathymetry and acoustic reflectance), (2) examine and record geologic characteristics of the sea floor, and (3) investigate the relation between substrate types and benthic communities, and (4) construct predictive maps of seafloor geomorphology and habitat distribution. Common substrates observed include rock, boulders, cobbles, rippled sand, bioturbated mud, and extensive beds of living horse mussels and scallops. Four principal sea-floor geomorphic types are distinguished by using video observations. Their distribution in lower and central Glacier Bay is predicted using a supervised, hierarchical decision-tree statistical classification of geophysical data.

  13. Benthic foraminifera of the Panamanian Province: distribution and origins.

    USGS Publications Warehouse

    Crouch, R.W.; Poag, C.W.

    1987-01-01

    Two hundred twenty-nine species of benthic foraminifera have been identified from 96 stations representing 33 localities on the eastern Pacific inner continental shelf, ranging from southern Peru to northern Baja California. Their distributions mark nearshore provincial boundaries that are nearly identical with those previously documented from the distribution of ostracodes and molluscs. Thirteen species are characteristic of the Panamanian Province, one is characteristic of the Chilean-Peruvian Province, and one is characteristic of the newly proposed Sonoran Subprovince. Seventeen species (7%) appear to be endemic to the eastern Pacific. Fifty-eight (25%) of the species recognized are disjunct from population centers in the western Pacific, 134 species (59%) are disjunct from modern assemblages of the Atlanto-Carribean region, and 40 species (17%) are disjunct from both the western Pacific and the Atlanto-Caribbean. The distribution of the remaining 57 species (25%) is poorly documented; we classify them as of unknown origin. -Authors

  14. Selective responses of benthic foraminifera to thermal pollution.

    PubMed

    Titelboim, Danna; Almogi-Labin, Ahuva; Herut, Barak; Kucera, Michal; Schmidt, Christiane; Hyams-Kaphzan, Orit; Ovadia, Ofer; Abramovich, Sigal

    2016-04-15

    Persistent thermohaline pollution at a site along the northern coast of Israel, due to power and desalination plants, is used as a natural laboratory to evaluate the effects of rising temperature and salinity levels on benthic foraminifera living in shallow hard-bottom habitats. Biomonitoring of the disturbed area and a control station shows that elevated temperature is a more significant stressor compared to salinity, thus causing a decrease in abundance and richness. Critical temperature thresholds were observed at 30 and 35°C, the latter representing the most thermally tolerant species in the studied area Pararotalia calcariformata, which is the only symbiont-bearing species observed within the core of the heated area. Common species of the shallow hard-bottom habitats including several Lessepsian invaders are almost absent in the most exposed site indicating that excess warming will likely impede the survival of these species that currently benefit from the ongoing warming of the Eastern Mediterranean. PMID:26895595

  15. Benthic exchange and biogeochemical cycling in permeable sediments.

    PubMed

    Huettel, Markus; Berg, Peter; Kostka, Joel E

    2014-01-01

    The sandy sediments that blanket the inner shelf are situated in a zone where nutrient input from land and strong mixing produce maximum primary production and tight coupling between water column and sedimentary processes. The high permeability of the shelf sands renders them susceptible to pressure gradients generated by hydrodynamic and biological forces that modulate spatial and temporal patterns of water circulation through these sediments. The resulting dynamic three-dimensional patterns of particle and solute distribution generate a broad spectrum of biogeochemical reaction zones that facilitate effective decomposition of the pelagic and benthic primary production products. The intricate coupling between the water column and sediment makes it challenging to quantify the production and decomposition processes and the resultant fluxes in permeable shelf sands. Recent technical developments have led to insights into the high biogeochemical and biological activity of these permeable sediments and their role in the global cycles of matter.

  16. Response of benthic insect species to changes in stream velocity resulting from stripmining disturbance

    SciTech Connect

    Stair, Jr., D. M.; Tolbert, V. R.

    1980-01-01

    Increased stream velocity resulting from increased runoff may cause considerable alterations in benthic communities. Stream velocity in disturbed watersheds can exceed tolerance limits of even the most resistant species. Increased velocities may also adversely impact benthic communities by increasing bedload movement, thus destroying habitats or physically abrading individuals. Studies are underway to document bedload movement and effects on benthic communities in mining disturbed streams. Additional studies are being initiated to determine if there are additive effects from the combination of increased stream velocity and sediment movement.

  17. Fish-derived nutrient hotspots shape coral reef benthic communities.

    PubMed

    Shantz, Andrew A; Ladd, Mark C; Schrack, Elizabeth; Burkepile, Deron E

    2015-12-01

    Animal-derived nutrients play an important role in structuring nutrient regimes within and between ecosystems. When animals undergo repetitive, aggregating behavior through time, they can create nutrient hotspots where rates of biogeochemical activity are higher than those found in the surrounding environment. In turn, these hotspots can influence ecosystem processes and community structure. We examined the potential for reef fishes from the family Haemulidae (grunts) to create nutrient hotspots and the potential impact of these hotspots on reef communities. To do so, we tracked the schooling locations of diurnally migrating grunts, which shelter at reef sites during the day but forage off reef each night, and measured the impact of these fish schools on benthic communities. We found that grunt schools showed a high degree of site fidelity, repeatedly returning to the same coral heads. These aggregations created nutrient hotspots around coral heads where nitrogen and phosphorus delivery was roughly 10 and 7 times the respective rates of delivery to structurally similar sites that lacked schools of these fishes. In turn, grazing rates of herbivorous fishes at grunt-derived hotspots were approximately 3 times those of sites where grunts were rare. These differences in nutrient delivery and grazing led to distinct benthic communities with higher cover of crustose coralline algae and less total algal abundance at grunt aggregation sites. Importantly, coral growth was roughly 1.5 times greater at grunt hotspots, likely due to the important nutrient subsidy. Our results suggest that schooling reef fish and their nutrient subsidies play an important role in mediating community structure on coral reefs and that overfishing may have important negative consequences on ecosystem functions. As such, management strategies must consider mesopredatory fishes in addition to current protection often offered to herbivores and top-tier predators. Furthermore, our results suggest that

  18. Benthic macrofauna data for San Francisco Bay, California, September 1986

    USGS Publications Warehouse

    Schemel, Laurence E.; Thompson, J.K.; Harmon, J.G.; Yost, B.T.

    1995-01-01

    Benthic macrofauna were collected during September 1986 to evaluate locations for long-term monitoring stations as part of the U.S. Geological Survey Regional Effects Monitoring Program in San Francisco Bay, California. Three to ten replicate samples were collected with a modified Van Veen sampler (0.05 m2 area) at ten locations. One box core sample (0.06 m2 area) was collected at seven to the ten locations. Six of the box core samples were split into an upper 10 cm sample and a deeper sample before analysis. Macrofauna specimens were identified to the lowest possible taxon, usually genus and species, then counted. An average of 88 percent of the benthic macrofauna specimens were identified to the species level. The fraction identified varied among stations from 54 to 98 percent. Nematodes and oligochaetes accounted for most of the unidentified specimens. Relative to the total number of species identified in five replicates at each location, an average of 90 percent of the species were collected with three replicates. In general, species with high to moderate abundances were present in all replicates, and species collected only after three or more replicates averaged less than one specimen per replicate. Results from the box cores showed that the dominant species were most abundant in the upper 10 cm, the depth of sediment that can be adequately sampled with a modified Van Veen sampler. On the basis of the number of species and their abundances at each location, seven of the ten locations were selected for sampling in the regular program, which began in March 1987.

  19. Effects of triclosan on marine benthic and epibenthic organisms.

    PubMed

    Perron, Monique M; Ho, Kay T; Cantwell, Mark G; Burgess, Robert M; Pelletier, Marguerite C

    2012-08-01

    Triclosan is an antimicrobial compound that has been widely used in consumer products such as toothpaste, deodorant, and shampoo. Because of its widespread use, triclosan has been detected in various environmental media, including wastewater, sewage sludge, surface waters, and sediments. Triclosan is acutely toxic to numerous aquatic organisms, but very few studies have been performed on estuarine and marine benthic organisms. For whole sediment toxicity tests, the sediment-dwelling estuarine amphipod, Ampelisca abdita, and the epibenthic mysid shrimp, Americamysis bahia, are commonly used organisms. In the present study, median lethal concentration values (LC50) were obtained for both of these organisms using water-only and whole sediment exposures. Acute 96-h water-only toxicity tests resulted in LC50 values of 73.4 and 74.3 µg/L for the amphipod and mysid, respectively. For the 7-d whole sediment toxicity test, LC50 values were 303 and 257 mg/kg (dry wt) for the amphipod and mysid, respectively. Using equilibrium partitioning theory, these whole sediment values are equivalent to interstitial water LC50 values of 230 and 190 µg/L for the amphipod and mysid, respectively, which are within a threefold difference of the observed 96-h LC50 water-only values. Triclosan was found to accumulate in polychaete tissue in a 28-d bioaccumulation study with a biota-sediment accumulation factor of 0.23 kg organic carbon/kg lipid. These data provide some of the first toxicity data for triclosan with marine benthic and epibenthic species while also indicating a need to better understand the effects of other forms of sediment carbon, triclosan ionization, and organism metabolism of triclosan on the chemical's behavior and toxicity in the aquatic environment.

  20. Benthic foraminifera and environmental changes in Long Island Sound

    USGS Publications Warehouse

    Thomas, E.; Gapotchenko, T.; Varekamp, J.C.; Mecray, E.I.; Buchholtz ten Brink, M. R.

    2000-01-01

    Benthic foraminiferal faunas in Long Island Sound (LIS) in the 1940s and 1960s were of low diversity, and dominated by species of the genus Elphidium, mainly Elphidium excavatum clavatum, with common Buccella frigida and Eggerella advena. The distribution of these species was dominantly correlated with depth, but it was not clear which depth-related environmental variable was most important. Differences between faunas collected in 1996 and 1997, and in the 1940s and 1960s include a strong decrease in relative abundance of Eggerella advena over all LIS, an increase in relative abundance of Ammonia beccarii in western LIS, and a decrease in species diversity. The decreased diversity suggests that environmental stress caused the faunal changes. Oxygen isotope data for E. excavatum clavatum indicate that a change in salinity is not a probable cause. Carbon isotope data suggest that the supply of organic matter to the benthos increased since the early 1960s, with a stronger increase in western LIS where algal blooms have occurred since the early 1970s, possibly as a result of nutrient input by waste water treatment plants. These blooms or the resulting episodes of anoxia/hypoxia may have played a role in the increased relative abundance of A. beccarii. There is no clear explanation for the decreased abundance of E. advena, but changes in the phytoplankton composition (thus food supply) are a possible cause. Benthic foraminiferal faunal and stable isotope data have excellent potential as indicators of physicochemical environmental changes and their effects on the biota in LIS.

  1. Anthropogenic and natural disturbances to marine benthic communities in Antarctica

    SciTech Connect

    Lenihan, H.; Oliver, J.S.

    1995-05-01

    Sampling and field experiments were conducted from 1975 to 1990 to test how the structure of marine benthic communities around McMurdo Station, Antarctica varied with levels of anthropogenic contaminants in marine sediments. The structure of communities (e.g., infauna density, species composition, and life history characteristics) in contaminated and uncontaminated areas were compared with the structure of communities influenced by two large-scale natural disturbances, anchor ice formation and uplift or iceberg scour. Benthic communities changed radically along a steep spatial gradient of anthropogenic hydrocarbon, metal, and PCB contamination around McMurdo Station. The heavily contaminated end of the gradient, Winter Quarters Bay, was low in infaunal and epifaunal abundance and was dominated by a few opportunistic species of polychaete worms. The edge of the heavily contaminated bay, the transition area, contained several motile polychaete species with less opportunistic life histories. Uncontaminated sedimentary habitats harbored dense tube mats of infaunal animals numerically dominated by populations of polychaete worms, crustaceans, and a large suspension feeding bivalve. These species are generally large and relatively sessile, except for several crustacean species living among the tubes. Although the community patterns around anthropogenic and natural disturbances were similar, particularly motile and opportunistic species at heavily disturbed and marginal areas, the natural disturbances cover much greater areas of the sea floor about the entire Antarctic continent. On the other hand, recovery from chemical contamination is likely to take many more decades than recovery from natural disturbances as contaminant degradation is a slow process. 77 refs., 6 figs., 5 tabs.

  2. Benthic perspective on Earth's oldest evidence for oxygenic photosynthesis.

    PubMed

    Lalonde, Stefan V; Konhauser, Kurt O

    2015-01-27

    The Great Oxidation Event (GOE) is currently viewed as a protracted process during which atmospheric oxygen increased above ∼10(-5) times the present atmospheric level (PAL). This threshold represents an estimated upper limit for sulfur isotope mass-independent fractionation (S-MIF), an Archean signature of atmospheric anoxia that begins to disappear from the rock record at 2.45 Ga. However, an increasing number of papers have suggested that the timing for oxidative continental weathering, and by conventional thinking the onset of atmospheric oxygenation, was hundreds of million years earlier than previously thought despite the presence of S-MIF. We suggest that this apparent discrepancy can be resolved by the earliest oxidative-weathering reactions occurring in benthic and soil environments at profound redox disequilibrium with the atmosphere, such as biological soil crusts and freshwater microbial mats covering riverbed, lacustrine, and estuarine sediments. We calculate that oxygenic photosynthesis in these millimeter-thick ecosystems provides sufficient oxidizing equivalents to mobilize sulfate and redox-sensitive trace metals from land to the oceans while the atmosphere itself remained anoxic with its attendant S-MIF signature. As continental freeboard increased significantly between 3.0 and 2.5 Ga, the chemical and isotopic signatures of benthic oxidative weathering would have become more globally significant from a mass-balance perspective. These observations help reconcile evidence for pre-GOE oxidative weathering with the history of atmospheric chemistry, and support the plausible antiquity of a terrestrial biosphere populated by cyanobacteria well before the GOE.

  3. Fish-derived nutrient hotspots shape coral reef benthic communities.

    PubMed

    Shantz, Andrew A; Ladd, Mark C; Schrack, Elizabeth; Burkepile, Deron E

    2015-12-01

    Animal-derived nutrients play an important role in structuring nutrient regimes within and between ecosystems. When animals undergo repetitive, aggregating behavior through time, they can create nutrient hotspots where rates of biogeochemical activity are higher than those found in the surrounding environment. In turn, these hotspots can influence ecosystem processes and community structure. We examined the potential for reef fishes from the family Haemulidae (grunts) to create nutrient hotspots and the potential impact of these hotspots on reef communities. To do so, we tracked the schooling locations of diurnally migrating grunts, which shelter at reef sites during the day but forage off reef each night, and measured the impact of these fish schools on benthic communities. We found that grunt schools showed a high degree of site fidelity, repeatedly returning to the same coral heads. These aggregations created nutrient hotspots around coral heads where nitrogen and phosphorus delivery was roughly 10 and 7 times the respective rates of delivery to structurally similar sites that lacked schools of these fishes. In turn, grazing rates of herbivorous fishes at grunt-derived hotspots were approximately 3 times those of sites where grunts were rare. These differences in nutrient delivery and grazing led to distinct benthic communities with higher cover of crustose coralline algae and less total algal abundance at grunt aggregation sites. Importantly, coral growth was roughly 1.5 times greater at grunt hotspots, likely due to the important nutrient subsidy. Our results suggest that schooling reef fish and their nutrient subsidies play an important role in mediating community structure on coral reefs and that overfishing may have important negative consequences on ecosystem functions. As such, management strategies must consider mesopredatory fishes in addition to current protection often offered to herbivores and top-tier predators. Furthermore, our results suggest that

  4. Selective responses of benthic foraminifera to thermal pollution

    NASA Astrophysics Data System (ADS)

    Titelboim, Danna; Almogi-Labin, Ahuva; Herut, Barak; Kucera, Michal; Schmidt, Christiane; Hyams-Kaphzan, Orit; Ovadia, Ofer; Abramovich, Sigal

    2016-04-01

    Predictions of future climate and recent observations point towards a trend of rising temperatures in the Middle East region. The temperature rise propagates into the marine environment, with shallow, coastal ecosystems being most affected. An ideal model system to study the effect of increased temperatures in coastal ecosystems is presented by benthic foraminifera. The persistent of thermohaline pollution at a site along the northern coast of Israel, attributed to a power and desalination plant, is used as a natural laboratory to evaluate the effects of rising temperature and salinity on benthic foraminifera living in shallow hard bottom habitats. Biomonitoring of the disturbed area and a control station shows that elevated temperature is a more significant stressor than salinity. The deleterious effect of extreme temperatures is indicated by a decrease in numerical abundances and reduced species richness, eventually leading to substantial changes in community composition. Critical temperature thresholds were observed at 30° C and 35° C, the latter observed by the most thermally tolerant species Pararotalia calcariformata, the only symbiont bearing species observed within the heated area. Common species of the shallow hard bottom habitats are almost absent from the most extreme site indicating that they presently live very close to their upper temperature threshold, and that excess warming will likely impede their future survival in the Eastern Mediterranean. Several of these species are either proven or suspected to be tropical Lessepsian. Thus, considering present models of expected north-western future expansion of Lessepsian species in the Mediterranean, our study show that it is important to consider excess warming as a major stressor that will limit their distribution.

  5. Benthic nutrient sources to hypereutrophic Upper Klamath Lake, Oregon, USA

    USGS Publications Warehouse

    Kuwabara, J.S.; Topping, B.R.; Lynch, D.D.; Carter, J.L.; Essaid, H.I.

    2009-01-01

    Three collecting trips were coordinated in April, May, and August 2006 to sample the water column and benthos of hypereutrophic Upper Klamath Lake (OR, USA) through the annual cyanophyte bloom of Aphanizomenon flos-aquae. A porewater profiler was designed and fabricated to obtain the first high-resolution (centimeter-scale) estimates of the vertical, concentration gradients of macro- and micronutrients for diffusive-flux determinations. A consistently positive benthic flux for soluble reactive phosphorus (SRP) was observed with solute release from the sediment, ranging between 0.4 and 6.1 mg/m2/d. The mass flux over an approximate 200-km2 lake area was comparable in magnitude to riverine inputs. An additional concern, related to fish toxicity was identified when dissolved ammonium also displayed consistently positive benthic fluxes of 4 to 134 mg/m2/d, again, comparable to riverine inputs. Although phosphorus was a logical initial choice by water quality managers for the limiting nutrient when nitrogen-fixing cyanophytes dominate, initial trace-element results from the lake and major inflowing tributaries suggested that the role of iron limitation on primary productivity should be investigated. Dissolved iron became depleted in the lake water column during the course of the algal bloom, while dissolved ammonium and SRP increased. Elevated macroinvertebrate densities, at least of the order of 104 individuals/m2, suggested, that the diffusive-flux estimates may be significantly enhanced, by bioturbation. In addition, heat-flux modeling indicated that groundwater advection of nutrients could also significantly contribute to internal nutrient loading. Accurate environmental assessments of lentic systems and reasonable expectations for point-source management require quantitative consideration of internal solute sources ?? 2009 SETAC.

  6. Holocene Deep Ocean Variability Detected with Individual Benthic Foraminifera

    NASA Astrophysics Data System (ADS)

    Bova, S. C.; Herbert, T.; Fox-Kemper, B.

    2015-12-01

    Historical observations of deep ocean temperatures (>700 m water depth) show apparently unprecedented rates of warming over the past half century that parallel observed surface warming, on the order of 0.1°C/decade (Purkey and Johnson 2010). Most water masses below 700 m depth, however, have not been at the sea surface where they exchange heat and carbon with the atmosphere since well before industrialization (Gebbie and Huybers 2012). How then has the heat content of isolated deep water masses responded to climate change over the last century? In models, wave mechanisms propagate thermocline anomalies quickly (Masuda et al. 2010), but these dynamics are not fully understood. We therefore turn to the sedimentary record to constrain the bounds of earlier variability from Holocene anomalies. The oxygen isotopic composition (δ18O) of individual benthic foraminifera provide approximately month-long snapshots of the temperature and salinity of ambient deep water during calcification. We exploit the short lifespan of these organisms to reconstruct variability in δ18Oshell, and thus the variability in deep water temperature and salinity, during five 200-yr Holocene intervals at 1000 m water depth in the Eastern Equatorial Pacific (EEP). Modern variability in benthic foraminifer δ18O was too weak to detect but variability at 1000 m water depth in the EEP exceeded our detection limit during two Holocene intervals at high confidence (p<0.01), with δ18O anomalies up to ~0.6 ± 0.15‰ that persist for a month or longer. Although the source of these anomalies remains speculative, rapid communication between the surface and deep ocean that operates on human timescales, faster than previously recognized, or intrinsic variability that has not been active during the history of ocean observations are potential explanations. Further work combining models and high-resolution proxy data is needed to identify the mechanism and global extent of this type of subsurface variability

  7. Abundance fluctuations among benthic invertebrates in two pacific estuaries

    USGS Publications Warehouse

    Nichols, Frederic H.

    1985-01-01

    Long-term studies were used to examine (1) contrasting time scales and mechanisms of structural variations within two benthic communities and (2) the usefulness of long data sets for evaluating human impact. A 10-year study of a San Francisco Bay mudflat, the details of which are reported elsewhere, has revealed large short-term (on the order of months) variations in species abundances within a community composed predominantly of opportunistic species. The study site, located in a highly urbanized estuary, is subject to the influence of a nearby sewage-treatment facility. However, rapid changes in population size of the common species, in part due to periodic natural habitat disturbance, impedes the detection of anthropogenic influences on community composition. Only a very long-term data set may provide evidence of progressive change. Data collected for a 20-year period on the benthic community at 200 m depth in the main basin of Puget Sound, an environment subject to little apparent habitat disturbance show that numerical abundance of the common species can also change markedly. Here, however, numerical dominance shifts from one species to another at irregular, multiyear intervals. Recent increases in two heretofore rare species, and a significant increase in total numbers of individuals suggest that long-term changes may be occurring in this community. These two long-term data sets demonstrate the importance of measuring both the amplitude and the periodicity of fluctuations in population size of aquatic species as well as long-term fluctuations and patterns in environmental factors before attempting to demonstrate the effect of anthropogenic influences on aquatic communities. The results of these studies also demonstrate the usefulness of long-term data sets for revealing the potential importance of interactions among species in determining abundance patterns in the soft-bottom benthos.

  8. Benthic perspective on Earth's oldest evidence for oxygenic photosynthesis.

    PubMed

    Lalonde, Stefan V; Konhauser, Kurt O

    2015-01-27

    The Great Oxidation Event (GOE) is currently viewed as a protracted process during which atmospheric oxygen increased above ∼10(-5) times the present atmospheric level (PAL). This threshold represents an estimated upper limit for sulfur isotope mass-independent fractionation (S-MIF), an Archean signature of atmospheric anoxia that begins to disappear from the rock record at 2.45 Ga. However, an increasing number of papers have suggested that the timing for oxidative continental weathering, and by conventional thinking the onset of atmospheric oxygenation, was hundreds of million years earlier than previously thought despite the presence of S-MIF. We suggest that this apparent discrepancy can be resolved by the earliest oxidative-weathering reactions occurring in benthic and soil environments at profound redox disequilibrium with the atmosphere, such as biological soil crusts and freshwater microbial mats covering riverbed, lacustrine, and estuarine sediments. We calculate that oxygenic photosynthesis in these millimeter-thick ecosystems provides sufficient oxidizing equivalents to mobilize sulfate and redox-sensitive trace metals from land to the oceans while the atmosphere itself remained anoxic with its attendant S-MIF signature. As continental freeboard increased significantly between 3.0 and 2.5 Ga, the chemical and isotopic signatures of benthic oxidative weathering would have become more globally significant from a mass-balance perspective. These observations help reconcile evidence for pre-GOE oxidative weathering with the history of atmospheric chemistry, and support the plausible antiquity of a terrestrial biosphere populated by cyanobacteria well before the GOE. PMID:25583484

  9. Benthic foraminiferal distribution in deep-water periplatform carbonate environments

    SciTech Connect

    Martin, R.E.

    1987-05-01

    In contrast to clastic depositional environments, bathymetric distribution of benthic foraminifera in deep-water carbonate environments has been largely neglected. Approximately 260 species and morphotypes of benthic foraminifera were identified from 12 sediment samples (piston core top and grab) collected along two transverses approximately 25 km apart across the northern (windward) margin of Little Bahama Bank at depths of 275 to 1135 m. Most species exhibit great variation in abundance with depth. However, Globocassidulina subglobosa, Cibicides rugosus, and Cibicides wuellerstorfi are all reliable depth indicators (Spearman's r > 0.91; p < 0.005), being most abundant at depths > 1000 m, and correspond to lower slope (> 900 m) periplatform aprons. Individual foraminiferal suborders (Miliolina, Rotaliina, Textulariina) show no consistent depth-related trends. However, certain operational taxonomic groups, such as reef-dwelling peneroplids and soritids (suborder Miliolina) and rotaliines (suborder Rotaliina) are significant more abundant at depths < 300 m (95% C.I.: 2.6 +/- 2.2% and 6.9 +/- 2.7%, respectively) than at greater depths (95% C.I.: 0.3 +/- 0.2% and 2.0 +/- 0.8%; Mann-Whitney U, p < 0.01), reflecting downslope bottom transport in proximity to bank-margin reefs. Small miliolines (i.e., suborder Miliolina minus peneroplids and soritids) and rosalinids and discorbids (suborder Rotaliina) are also more abundant at depths < 300 m (95% C.I.: 27.5 +/- 7.4% and 32.6 +/- 8.5%, respectively) than at greater depths (95% C.I.: 10.0 +/- 3.9% and 1.5 +/- 1.6%; Mann-Whitney U, p < 0.01) and are winnowed from the carbonate platform. Assemblages exhibit greatest variation in diversity (species number, s; Shannon-Weaver, H'; evenness, J') at depths > 900 m; indices for shallower assemblages tend to be grouped more tightly at relatively high values.

  10. Polar Layers

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA02153 Polar Layers

    This image of the south polar region shows layered material. It is not known if the layers are formed yearly or if they form over the period of 10s to 100s of years or more.

    Image information: VIS instrument. Latitude -80.3N, Longitude 296.2E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  11. Water conditions and geochemistry in northern Adriatic anoxia-prone areas and response of benthic faunas to oxygen deficiencies

    NASA Astrophysics Data System (ADS)

    Zuschin, Martin; Riedel, Bettina; Stachowitsch, Michael; Cermelj, Branko

    2010-05-01

    One predicted effect of global climate change, specifically global warming, is the increase in the temperatures and stratification of shallow coastal and estuarine systems. This, coupled with ongoing anthropogenic eutrophication, will exacerbate hypoxia and benthic mortalities, significantly damaging these critical marine ecosystems. These phenomena are particularly severe on sublitoral soft-bottoms such as the poorly sorted silty sands at the study site in the northern Adriatic Sea. We deployed a specially developed underwater chamber to artificially induce anoxia in situ. Our Experimental Anoxia Generating Unit (EAGU) is a large plexiglass chamber that combines a digital camera with oxygen/hydrogen sulphide/pH sensors along with flashes and battery packs. The unit can be deployed for up to five days to autonomously generate oxygen crises and quantify both physico-chemical parameters and benthic responses. The system is initially positioned in an "open" configuration (open-sided aluminium frame) over the benthic fauna ("control" experiment). After 24 h the EAGU is switched to its "closed" configuration (plexiglass enclosure) and repositioned over the same assemblage. In this contribution, we focus on the natural oxygen content, temperature and pH of bottom waters during summer, the course of oxygen decrease during our experiments and the onset of H2S development. Oxygen content of the bottom water, a few centimetres above the sediment-water interface, ranges from ~3.5-8 but is mostly between 4-6 ml l-1 during July to September of the study periods (2005 and 2006) and decreases to zero within ~1-3 days after initiation of our experiments. In parallel, H2S starts to develop at the onset of anoxia. Water temperatures at the bottom were stable during experiments and ranged from 18.5°C to 21.4°C, but pH decreased from 8.3 to 8.1 at the beginning to 7.9 to 7.7 at the end of the experiments. Sediment profiling indicates that the diffusive benthic boundary layer is

  12. Similarity & Instability in Flows Over Permeable Layers (Invited)

    NASA Astrophysics Data System (ADS)

    Ghisalberti, M.

    2013-12-01

    Permeable obstructions (such as seagrass meadows) are prevalent in the benthic region of freshwater and coastal environments. Their impact on the near-bed flow, turbulence and vertical transport is profound. Here, I use particle imaging and point velocity measurements in both steady and oscillatory flows to demonstrate three salient features of environmental flows over permeable layers: (1) A framework developed for vegetation canopies has the capacity to predict flow, turbulence and mixing properties over a wide range of permeable layers (from sediment beds to coral reefs to 'urban' canopies to ancient rangeomorph communities). (2) Steady flows are characterized by the development of a Kelvin-Helmholtz-type instability at the interface between the permeable layer and the free flow. These coherent structures dominate vertical mixing at the interface and generate regular oscillations in flow and transport. The height of the permeable layer relative to its drag length scale defines three regimes of obstructed shear flow. (3) Such instability is also observed in oscillatory flow when both the Reynolds and Keulegan-Carpenter numbers exceed threshold values. This is important in the prediction of residence time in ecologically-significant benthic habitats that exist in shallow (and therefore, typically, wave-dominated) coastal regions.

  13. Comparison of benthic foraminifera inside and outside a sulphur-oxidizing bacterial mat from the present oxygen-minimum zone off Pakistan (NE Arabian Sea)

    NASA Astrophysics Data System (ADS)

    Erbacher, Jochen; Nelskamp, Susanne

    2006-05-01

    Assemblages of live (Rose-Bengal-stained) and dead benthic foraminifera and stable oxygen and carbon isotopic composition of live benthic foraminifera were studied in and outside a bacterial mat composed of the large sulphur-oxidizing bacteria Thioploca and Beggiatoa from the oxygen-minimum zone off Pakistan (NE Arabian Sea). Two cores from the same Multicorer retrieved a bacterial mat and ambient sediment. The dominant species ( Globobulimina affinis, G. turgida, Bolivina pacifica, B. pseudopunctata, Uvigerina peregrina and Buliminella tenuata) in both cores are characteristic for dysoxic oxygen minimum zone conditions. The most significant difference between the two cores is the reduced number of stained benthic foraminifera (SBF) in the top 0.5 cm of the bacterial mat. Faunal densities of stained species are more than four times higher in the sediment surface sample (0-0.5 cm) outside the bacterial mat, at a distance of only 1.5 m. All stained species, however, observed outside the Beggiatoa/Thioploca mat were also observed in the core with the mat. Two species, Virgulinella fragilis and Bolivina dilatata, occur exclusively in the core with the bacterial mat. The diversity within the bacterial mat core is thus slightly higher than outside. Furthermore, the abundances of the species Buliminella morgani, B. tenuata and Alliatina primitiva are substantially higher in the bacterial mat than outside. Globobuliminids, on the other hand, seem to prefer the conditions outside the bacterial mat and are five times more frequent in the core taken outside the bacterial mat. Benthic foraminifers inhabit a broader microhabitat range outside the bacterial mat (˜5 cm) than within (3.5 cm). A marked decrease in SBF abundances was observed at the level of a black sulphur-rich layer which is interpreted to mark the shallow redox front below the bacterial mat. Stable carbon isotope analyses on live benthic foraminifera do not support a relation of the investigated Beggiatoa

  14. PROCEDURES FOR DERIVING EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: ENDRIN

    EPA Science Inventory

    This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations of the insecticide endrin in sediment which are protective of the presence of benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it accoun...

  15. RESPONSES OF ESTUARINE BENTHIC INVERTEBRATES TO SEDIMENT BURIAL: THE IMPORTANCE OF MOBILITY AND ADAPTATION

    EPA Science Inventory

    Estuarine benthic organisms are frequently subjected to disturbance events caused by hydrodynamic processes that disrupt and move the sediment in which the animals reside, however the mechanisms by which physical disturbance processes affect infaunal and epifaunal populations and...

  16. Ecological periodic tables for nekton and benthic macrofaunal community usage of estuarine habitats Slides

    EPA Science Inventory

    Ecological periodic tables for nekton and benthic macrofaunal community usage of estuarine habitats Steven P. Ferraro, U.S. Environmental Protection Agency, Newport, OR Background/Questions/Methods The chemical periodic table, the Linnaean system of classification, and the Her...

  17. Relationship Between Nutrient Enrichment and Benthic Function: Local Effects and Spatial Patterns

    EPA Science Inventory

    Eutrophication-induced changes to benthic structure and function are problems of enormous ecological and economic significance. Understanding the relationships between nutrient enrichment and effects, modifying factors such as localized transport time, and symptoms of eutrophica...

  18. RELATIONSHIP BETWEEN METABOLISM AND BIOACCUMULATION OF BENZO[A]PYRENE IN BENTHIC INVERTEBRATES

    EPA Science Inventory

    The potential influence of polycyclic aromatic hydrocarbon (PAH) metabolism on bioaccumulation is well accepted, but rarely has been examined in many species of benthic invertebrates that commonly are found in contaminated sediments, or used in bioaccumulation or toxicity tests. ...

  19. PROCEDURES FOR DERIVING EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: DIELDRIN

    EPA Science Inventory

    This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations of the insecticide dieldrin in sediment which are protective of the presence of benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it acco...

  20. Ecological periodic tables for benthic macrofaunal usage of estuarine habitats in the US Pacific Northwest

    EPA Science Inventory

    Estuary-wide benthic macrofauna─habitat associations were determined for 9 habitats (intertidal eelgrass [Zostera marina], dwarf eelgrass [Zostera japonica], oyster [Crassostrea gigas], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis], shell, sand, mud,...

  1. Seasonal variation of benthic macro invertebrates from Tons River of Garhwal Himalaya Uttarakhand.

    PubMed

    Negi, R K; Mamgain, Sheetal

    2013-11-15

    Present investigation was carried out to assess the seasonal variation of benthic macro-invertebrates from the Tons river, a tributary of Yamuna River in Garhwal Himalaya, Uttrakhand during December, 2007 to November, 2009. The seasonal benthic diversity was correlated with various physic-chemical parameters which documented that the macrobenthic diversity is mostly regulated by the dissolved oxygen in the water while temperature and free CO2 were found to be inversely correlated with the benthic fauna. Maximum diversity of benthos was reported at the upstream site ('H' 0.204) during the winter season while it was recorded minimum during the rainy season at all the sites. Maximum diversity is reported during the winter season at all the sites. The benthic fauna is represented by three phylum, 4 classes and 10 orders with Insecta emerging as the most dominant class. Maximum genera were reported from midstream site as it acts as ecotone between upstream and downstream.

  2. DEVELOPMENT OF BENTHIC MACROINVERTEBRATE INDEX FOR MEASURING THE CONDITION OF STREAMS AT A REGIONAL SCALE

    EPA Science Inventory

    A multimetric macroinvertebrate index of stream condition was developed for the Mid-Atlantic Highlands Region of the United States. Benthic macroinvertebrate samples were collected from 562 first through third order streams between 1993 and 1995. Macroinvertebrates were collect...

  3. ABUNDANCE AND DISTRIBUTION OF INDIGENOUS, NONINDIGENOUS, AND CRYPTOGENIC BENTHIC MACROFAUNA IN WILLAPA BAY, WASHINGTON, USA

    EPA Science Inventory

    Benthic macrofaunal samples were collected in Willapa Bay, WA, in four habitats [eelgrass (Zostera marina), Atlantic cordgrass (Spartina alterniflora), mud shrimp (Upogebia pugettensis), ghost shrimp (Neotrypaea californiensis)] in 1996 and in seven habitats (Zostera, Spartina, U...

  4. Biogeographical Patterns of Marine Benthic Invertebrates Along the Atlantic Coast of the Northeastern USA

    EPA Science Inventory

    Aim Examine the biogeography of marine benthic invertebrates of the Atlantic coast of the northeastern USA, compare the results to historical biogeographic studies, define physical-chemical factors affecting species distributions, and provide biogeographic information needed to ...

  5. Seasonal variation of benthic macro invertebrates from Tons River of Garhwal Himalaya Uttarakhand.

    PubMed

    Negi, R K; Mamgain, Sheetal

    2013-11-15

    Present investigation was carried out to assess the seasonal variation of benthic macro-invertebrates from the Tons river, a tributary of Yamuna River in Garhwal Himalaya, Uttrakhand during December, 2007 to November, 2009. The seasonal benthic diversity was correlated with various physic-chemical parameters which documented that the macrobenthic diversity is mostly regulated by the dissolved oxygen in the water while temperature and free CO2 were found to be inversely correlated with the benthic fauna. Maximum diversity of benthos was reported at the upstream site ('H' 0.204) during the winter season while it was recorded minimum during the rainy season at all the sites. Maximum diversity is reported during the winter season at all the sites. The benthic fauna is represented by three phylum, 4 classes and 10 orders with Insecta emerging as the most dominant class. Maximum genera were reported from midstream site as it acts as ecotone between upstream and downstream. PMID:24511693

  6. BIOGEOGRAPHY OF BENTHIC MACROINVERTEBRATES IN ESTUARIES ALONG THE GULF OF MEXICO AND WESTERN ATLANTIC COASTS

    EPA Science Inventory

    The community composition of benthic macroinvertebrates from 870 estuarine sites was examined to determine boundaries of biogeographical provinces along the Gulf of Mexico and western Atlantic coasts of the United States. Our objective was to confirm or challenge established boun...

  7. Effect of Organic Enrichment and Hypoxia on the Biodiversity of Benthic Communities in Narragansett Bay

    EPA Science Inventory

    Excessive input of nitrogen to coastal waters leads to eutrophication and hypoxia that reduce biodiversity and impair key ecosystem services provided by benthic communities; for example, fish and shellfish production, bioturbation, nutrient cycling, and water filtration. Hypoxia ...

  8. Validation of soft bottom benthic habitats identified by single-beam acoustics.

    PubMed

    Freitas, R; Sampaio, L; Oliveira, J; Rodrigues, A M; Quintino, V

    2006-01-01

    Acoustic diversity charts were produced for a Portuguese soft bottom mid-shelf area, depth from 30 to 90 m, using a single-beam echo sounder coupled to the acoustic systems QTC VIEW Series IV and V. A similar acoustic pattern was identified by both systems, which, after ground-truth interpretation based in available sediment and biological data, established a preliminary spatial distribution model of the benthic habitats in this coastal area. However, some of the acoustic areas were interpreted using one or very few sediment and benthic samples. A specific validation survey was conducted a posteriori, in which the positioning of the sediment and benthic community sampling sites was based on the acoustic diversity previously identified. The results clearly confirm the benthic habitats distribution model suggested by the acoustic method, indicating a high potential for the use of such approach in the identification and mapping of large-scale soft bottom coastal shelf habitat diversity. PMID:16266728

  9. PROCEDURES FOR DERIVING EQUILIBRIUM PARTITIONING BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISM: PAH MIXTURES

    EPA Science Inventory

    This equilibrium partitioning sediment benchmark (ESB) document describes procedures to derive concentrations of PAH mixtures in sediment which are protective of the presence of benthic organisms. The equilibrium partitioning (EqP) approach was chosen because it accounts for t...

  10. A cross-continental comparison of the effects of flow intermittence on benthic invertebrate assemblages

    EPA Science Inventory

    Although temporary rivers are widespread freshwater systems, they have been poorly studied by ecologists and are largely ignored in water management plans, practices and policies. If the effects of dry events on benthic invertebrates have been reported individually from different...

  11. Rates of benthic protozoan grazing on free and attached sediment bacteria measured with fluorescently stained sediment.

    PubMed

    Starink, M; Krylova, I N; Bär-Gilissen, M J; Bak, R P; Cappenberg, T E

    1994-07-01

    In order to determine the importance of benthic protozoa as consumers of bacteria, grazing rates have been measured by using monodispersed fluorescently labeled bacteria (FLB). However, high percentages of nongrazing benthic protists are reported in the literature. These are related to serious problems of the monodispersed FLB method. We describe a new method using 5-(4,6-dichlorotriazin-2-yl)-aminofluorescein (DTAF)-stained sediment to measure in situ bacterivory by benthic protists. This method is compared with the monodispersed FLB technique. Our estimates of benthic bacterivory range from 61 to 73 bacteria protist h and are about twofold higher than the results of the monodispersed FLB method. The number of nongrazing protists after incubation for 15 min with DTAF-stained sediment is in agreement with theoretical expectation. We also tested the relative affinity for FLB of protists and discuss the results with respect to a grazing model.

  12. Benthic community and sediment quality assessment of Port Hope Harbour, Lake Ontario

    SciTech Connect

    Hart, D.R.; McKee, P.M.; Burt, A.J.; Goffin, M.J.

    1986-01-01

    Sediments in Port Hope Harbour, Lake Ontario, have been heavily contaminated by radionuclides and heavy metals from a radium recovery plant, a uranium refinery, and other industrial activities. Spatial patterns in surficial sediment contamination, benthic community structure, and bioaccumulation of contaminants were assessed to determine possible relationships and potential environmental hazards in the event of dredging. Benthic community differences in species composition and density between inner and outer harbour areas corresponded with both habitat and sediment quality differences. Sediment loss-on-ignition, nitrogen, iron, copper, lead, chromium, zinc, and nickel concentrations in the inner harbour exceeded provincial guidelines for open water disposal of dredged spoils. Only iron exceeded those guidelines in the other harbour. Tissue levels of radionuclides and heavy metals in benthic invertebrates were greatest at the most heavily contaminated stations in the inner harbour. Reduced benthic densities and maximum sediment contamination occurred near a refinery cooling water discharge. 59 references, 3 figures, 5 tables.

  13. Mud, Macrofauna and Microbes: An ode to benthic organism-abiotic interactions at varying scales

    EPA Science Inventory

    Benthic environments are dynamic habitats, subject to variable sources and rates of sediment delivery, reworking from the abiotic and biotic processes, and complex biogeochemistry. These activities do not occur in a vacuum, and interact synergistically to influence food webs, bi...

  14. ENVIRONMENTAL INFLUENCES ON BENTHIC COMMUNITY STRUCTURE IN A GREAT LAKES EMBAYMENT

    EPA Science Inventory

    An Intensified Environmental Monitoring and Assessment Program (EMAP) sampling grid in the St. Louis River estuary of western Lake Superior was used toassess the relationship between surficial sediment characteristics and benthic community structure. Ninety sites within two habit...

  15. Benthic status of near-shore fishing grounds in the central Philippines and associated seahorse densities.

    PubMed

    Marcus, J E; Samoilys, M A; Meeuwig, J J; Villongco, Z A D; Vincent, A C J

    2007-09-01

    Benthic status of 28 near-shore, artisanal, coral reef fishing grounds in the central Philippines was assessed (2000-2002) together with surveys of the seahorse, Hippocampus comes. Our measures of benthic quality and seahorse densities reveal some of the most degraded coral reefs in the world. Abiotic structure dominated the fishing grounds: 69% of the benthos comprised rubble (32%), sand/silt (28%) and dead coral (9%). Predominant biotic structure included live coral (12%) and Sargassum (11%). Rubble cover increased with increasing distance from municipal enforcement centers and coincided with substantial blast fishing in this region of the Philippines. Over 2 years, we measured a significant decrease in benthic 'heterogeneity' and a 16% increase in rubble cover. Poor benthic quality was concomitant with extremely low seahorse densities (524 fish per km(2)). Spatial management, such as marine reserves, may help to minimize habitat damage and to rebuild depleted populations of seahorses and other reef fauna.

  16. Benthic biotope index for classifying habitats in the Sado Estuary: Portugal.

    PubMed

    Caeiro, S; Costa, M H; Goovaerts, P; Martins, F

    2005-12-01

    An integration of sediment physical, chemical, biological, and toxicity data is necessary for a meaningful interpretation of the complex sediment conditions in the marine environment. Assessment of benthic community is a vital component for that interpretation, yet their evaluation is complex and requires a large expenditure of time and funds. Thus, there is a need for new tools that are less expensive and more understandable for managers. This paper presents a benthic biotope index to predict from physical and chemical variables the occurrence of macrobenthic habitats. Parameters such as sediment type, organic matter, depth, and hydrodynamic parameters were selected, through a discriminant analysis, to compute the index. Other authors have used multivariate methods to determine the benthic biotopes for Sado Estuary. The index proved to be a valid tool to classify and assess the spatial patterns of benthic habitat and to synthesize stress biotope gradients.

  17. POTENTIAL USE OF BENTHIC ALGAE AS HYDROLOGIC INDICATORS FOR HEADWATER STREAMS: SOME DATA EXPLORATION

    EPA Science Inventory

    Benthic algae were sampled to determine the utility of algal communities as indicators of hydrologic regime as part of a national survey involving habitat measurements and community assessments. Streams from four forests near Cincinnati were classified according to hydrologic pe...

  18. Turnover and paleoenvironmental changes across the Cretaceous/Paleogene boundary at the Galanderud section (Northern Alborz, Iran) based on benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Asgharianrostami, Masoud; Leckie, R. Mark; Font, Eric; Frontalini, Fabrizio; Koeberl, Christian

    2014-05-01

    A high-resolution quantitative study of benthic foraminifera across the expanded and continuous Cretaceous/Paleogene (K/Pg) boundary at the Galanderud section in northern Iran provides an excellent record of the K/Pg event. The benthic foraminiferal assemblages, in contrast to the planktic foraminifers, did not suffer mass extinction at the K/Pg boundary. Uppermost Maastrichtian assemblages are well preserved and highly diverse. Only ~3% of the benthic species became extinct, including Bolivinoides draco, Eouvigerina subsculptura, Neoflabellina sp. and Praebulimina reussi. Other species are temporarily absent for a short interval after the K/Pg boundary. Benthic foraminifera indicate outer neritic-uppermost bathyal depths during the Plummerita hantkeninoides Zone until 70 cm below the K/Pg boundary. This interval contains abundant species of Bolivinoides draco, Gaudryina pyramidata, Cibicidoides hyphalus, P. reussi, and Sitella cushmani. The paleodepth decreased to outer neritic in the uppermost Maastrichtian based on the dominance of Stensioeina excolata, G. pyramidata, Cibicidoides pseudoacutus, and Coryphostoma incrassata forma gigantea. On the other hand, some species such as P. reussi and C. hyphalus, which are normally found at bathyal depths, decreased in their abundances. These data suggest a sea-level fall at the end of Maastrichtian. Additional evidence for sea-level fall is a decrease of planktic/benthic ratio from ~60% to ~40% in the uppermost Maastrichtian. The K/Pg clay layer is characterized by a high abundance of opportunistic species such as Cibicidoides spp., C. pseudoacutus, and Tappanina selemensis. The drastic change of benthic foraminiferal assemblages coincides with a sharp drop in magnetic susceptibility and %CaCO3, mass extinction of planktic foraminifera, a sharp enrichment in Ir, and a 2.25‰ negative excursion in ∂13C at the K/Pg boundary, which is largely compatible with the catastrophic effects of an asteroid impact on Earth that

  19. Spatial variability of benthic-pelagic coupling in an estuary ecosystem: consequences for microphytobenthos resuspension phenomenon.

    PubMed

    Ubertini, Martin; Lefebvre, Sébastien; Gangnery, Aline; Grangeré, Karine; Le Gendre, Romain; Orvain, Francis

    2012-01-01

    The high degree of physical factors in intertidal estuarine ecosystem increases material processing between benthic and pelagic compartments. In these ecosystems, microphytobenthos resuspension is a major phenomenon since its contribution to higher trophic levels can be highly significant. Understanding the sediment and associated microphytobenthos resuspension and its fate in the water column is indispensable for measuring the food available to benthic and pelagic food webs. To identify and hierarchize the physical/biological factors potentially involved in MPB resuspension, the entire intertidal area and surrounding water column of an estuarine ecosystem, the Bay des Veys, was sampled during ebb tide. A wide range of physical parameters (hydrodynamic regime, grain size of the sediment, and suspended matter) and biological parameters (flora and fauna assemblages, chlorophyll) were analyzed to characterize benthic-pelagic coupling at the bay scale. Samples were collected in two contrasted periods, spring and late summer, to assess the impact of forcing variables on benthic-pelagic coupling. A mapping approach using kriging interpolation enabled us to overlay benthic and pelagic maps of physical and biological variables, for both hydrological conditions and trophic indicators. Pelagic Chl a concentration was the best predictor explaining the suspension-feeders spatial distribution. Our results also suggest a perennial spatio-temporal structure of both benthic and pelagic compartments in the ecosystem, at least when the system is not imposed to intense wind, with MPB distribution controlled by both grain size and bathymetry. The benthic component appeared to control the pelagic one via resuspension phenomena at the scale of the bay. Co-inertia analysis showed closer benthic-pelagic coupling between the variables in spring. The higher MPB biomass observed in summer suggests a higher contribution to filter-feeders diets, indicating a higher resuspension effect in

  20. Spatial Variability of Benthic-Pelagic Coupling in an Estuary Ecosystem: Consequences for Microphytobenthos Resuspension Phenomenon

    PubMed Central

    Ubertini, Martin; Lefebvre, Sébastien; Gangnery, Aline; Grangeré, Karine; Le Gendre, Romain; Orvain, Francis

    2012-01-01

    The high degree of physical factors in intertidal estuarine ecosystem increases material processing between benthic and pelagic compartments. In these ecosystems, microphytobenthos resuspension is a major phenomenon since its contribution to higher trophic levels can be highly significant. Understanding the sediment and associated microphytobenthos resuspension and its fate in the water column is indispensable for measuring the food available to benthic and pelagic food webs. To identify and hierarchize the physical/biological factors potentially involved in MPB resuspension, the entire intertidal area and surrounding water column of an estuarine ecosystem, the Bay des Veys, was sampled during ebb tide. A wide range of physical parameters (hydrodynamic regime, grain size of the sediment, and suspended matter) and biological parameters (flora and fauna assemblages, chlorophyll) were analyzed to characterize benthic-pelagic coupling at the bay scale. Samples were collected in two contrasted periods, spring and late summer, to assess the impact of forcing variables on benthic-pelagic coupling. A mapping approach using kriging interpolation enabled us to overlay benthic and pelagic maps of physical and biological variables, for both hydrological conditions and trophic indicators. Pelagic Chl a concentration was the best predictor explaining the suspension-feeders spatial distribution. Our results also suggest a perennial spatio-temporal structure of both benthic and pelagic compartments in the ecosystem, at least when the system is not imposed to intense wind, with MPB distribution controlled by both grain size and bathymetry. The benthic component appeared to control the pelagic one via resuspension phenomena at the scale of the bay. Co-inertia analysis showed closer benthic-pelagic coupling between the variables in spring. The higher MPB biomass observed in summer suggests a higher contribution to filter-feeders diets, indicating a higher resuspension effect in

  1. Effects of coral reef benthic primary producers on dissolved organic carbon and microbial activity.

    PubMed

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

    2011-01-01

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

  2. A review of approaches for classifying benthic habitats and evaluating habitat quality.

    PubMed

    Diaz, Robert J; Solan, Martin; Valente, Raymond M

    2004-11-01

    We have assessed the current state of knowledge relative to methods used in assessing sub-tidal benthic habitat quality and the classification of benthic habitats. While our main focus is on marine habitat, we extensively draw on knowledge gained in freshwater systems where benthic assessment procedures are at an advanced stage of maturity. We found a broad range of sophistication/complication in terms of the methods applied in assessing and mapping benthic habitats. The simplest index or metric involved some assessment of species richness, while the most complicated required utilizing multi-variate analysis. The simplest mapping attempts equated physical substrate with benthic habitat while the most sophisticated relied on extensive environmental preference and groundtruth data for species of concern. The leading edge of methods for benthic habitat mapping involves combining the advances in optical and acoustic methods that allow for routine classifying and mapping of the seafloor with biological and habitat data for species of concern. The objective of this melding of dispirit methods is to produce benthic habitat maps with broad system wide coverage and sound biological underpinning. It is clear that the disparity in information density between the physical and biological sides of the equation currently hinder applicability and acceptability of benthic habitat mapping efforts. In addition to the lack of basic information on the biological and environmental tolerances of targeted species, the proliferation of metrics for characterizing and assessing biological conditions further clouds the usefulness of any broad scale mapping attempt. The problem of data density mismatch between physical and biological methods will likely not be solved until acoustic methods can routinely resolve the elusive biological components that make a physical substrate a habitat.

  3. Age differences between Atlantic and Pacific benthic d18O change at terminations

    NASA Astrophysics Data System (ADS)

    Lisiecki, L. E.; Raymo, M. E.

    2007-12-01

    Because a large fraction of benthic δ18O change is due to global ice volume change, benthic δ18O is often used as stratigraphic tool to place marine records on a common age model and as a proxy for the timing of ice volume/sea level change. These applications require the assumptions that δ18O change is rapidly transmitted throughout the deep ocean and that the effects of hydrographic changes are in phase with ice volume. Recently, Skinner and Shackleton [2005] found that the timing of benthic δ18O change at the last termination differed by 4500 years between two sites in the Atlantic and Pacific. Based on Mg/Ca paleothermometry, they argued that these age discrepancies resulted from a late temperature increase in the Pacific and millennial-scale circulation changes in the Atlantic. Do these results imply that benthic δ18O change may not accurately record the timing of terminations? We compare benthic δ18O records from 34 sites in the Atlantic and Pacific to evaluate the impact of ocean mixing rates and deep water changes on the relative timing of terminations recorded in benthic δ18O. Statistical analysis of sedimentation rates derived from the alignment of benthic δ18O suggests an Atlantic lead over Pacific benthic δ18O change for all terminations of the last 600 kyr. The magnitude of sedimentation rate change suggests an average termination age difference of 1000-1500 years between the Atlantic and Pacific, consistent with or slightly greater than the delay expected due to ocean mixing rates, given that most glacial meltwater probably enters the North Atlantic.

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

    PubMed Central

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

    2011-01-01

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

  5. Environmental Drivers of Benthic Flux Variation and Ecosystem Functioning in Salish Sea and Northeast Pacific Sediments

    PubMed Central

    Belley, Rénald; Snelgrove, Paul V. R.; Archambault, Philippe; Juniper, S. Kim

    2016-01-01

    The upwelling of deep waters from the oxygen minimum zone in the Northeast Pacific from the continental slope to the shelf and into the Salish Sea during spring and summer offers a unique opportunity to study ecosystem functioning in the form of benthic fluxes along natural gradients. Using the ROV ROPOS we collected sediment cores from 10 sites in May and July 2011, and September 2013 to perform shipboard incubations and flux measurements. Specifically, we measured benthic fluxes of oxygen and nutrients to evaluate potential environmental drivers of benthic flux variation and ecosystem functioning along natural gradients of temperature and bottom water dissolved oxygen concentrations. The range of temperature and dissolved oxygen encountered across our study sites allowed us to apply a suite of multivariate analyses rarely used in flux studies to identify bottom water temperature as the primary environmental driver of benthic flux variation and organic matter remineralization. Redundancy analysis revealed that bottom water characteristics (temperature and dissolved oxygen), quality of organic matter (chl a:phaeo and C:N ratios) and sediment characteristics (mean grain size and porosity) explained 51.5% of benthic flux variation. Multivariate analyses identified significant spatial and temporal variation in benthic fluxes, demonstrating key differences between the Northeast Pacific and Salish Sea. Moreover, Northeast Pacific slope fluxes were generally lower than shelf fluxes. Spatial and temporal variation in benthic fluxes in the Salish Sea were driven primarily by differences in temperature and quality of organic matter on the seafloor following phytoplankton blooms. These results demonstrate the utility of multivariate approaches in differentiating among potential drivers of seafloor ecosystem functioning, and indicate that current and future predictive models of organic matter remineralization and ecosystem functioning of soft-muddy shelf and slope seafloor

  6. Trace metals, PCBs, and PAHs in benthic (epipelic) diatoms from intertidal sediments; a pilot study

    SciTech Connect

    Stronkhorst, J.; Misdorp, R. ); Vos, P.C. )

    1994-06-01

    Intertidal sediments in many estuaries around the world have a history of contamination resulting from long term discharges of industrial, agricultural and domestic waste effluents. These contaminated sediments are now regarded as a major source of toxicants for bottom-related organisms which, in turn, may pass on certain contaminants (e.g. methylmercury, polychlorinated biphenyls (PCBs)) to organisms higher in the foodchain. Many studies have been conducted on the contamination of benthic macrofauna, estuarine fish and birds, but to our knowledge no research has yet been carried out on benthic diatoms which form the lowest trophic level of an intertidal ecosystem. Research on the effects of micro-contaminants on primary producers in marine ecosystems is mainly performed with phytoplankton. In the estuaries of temperate regions, benthic diatoms make a significant contribution to primary production in the ecosystem and are predated especially by deposit feeding Polychaete and Mollusca. Knowledge of the level of contamination in benthic diatoms is of major importance to recognize possible effects on growth rate and species composition of the benthic diatom populations and to understand the accumulation of toxicants into the foodchain. For chemical analysis it is difficult to obtain [open quote]pure[close quote] samples of benthic diatoms because they form part of the sediment. A similar problem occurs with the sampling of phytoplankton in turbid estuarine waters. The aim of this pilot study was (a) to improve a trap technique to collect pure samples of benthic diatoms of at least 2 gram dry weight for analysis of trace metals, PCBs and polyaromatic hydrocarbons (PAHs) and (b) to compare the concentrations in benthic diatoms with levels in sediment and some bottom-related organisms. 16 refs., 2 figs., 2 tabs.

  7. Benthic mineralization rates at two locations in the southern North Sea

    NASA Astrophysics Data System (ADS)

    Osinga, Ronald; Kop, Arjen J.; Duineveld, Gerard C. A.; Prins, Rudolf A.; Van Duyl, Fleur C.

    1996-12-01

    Benthic oxygen uptake, sulphate reduction and benthic bacterial production were measured at two contrasting locations in the southern North Sea: the shallow and turbulent Broad Fourteens area in the Southern Bight, and the deeper Oyster Grounds, a deposition area, where thermohaline stratification occurs during summer. Oxygen uptake and sulphate reduction showed a clear seasonal pattern in the Broad Fourteens area, indicating a supply of carbon to the benthic system that is closely related to the standing stock of carbon in the water column. This close benthic-pelagic coupling is probably due to the influence of the tide in this part of the North Sea, which keeps the water column permanently mixed. At the Oyster Grounds, no seasonal pattern was observed. Peaks in oxygen uptake and sulphate reduction were found in winter. Irregularly occurring events, such as storms and fishery-related activities, are likely to affect the benthic mineralization patterns in this area. Annual benthic carbon mineralization rates estimated from oxygen uptake rates were 44 gC·m -2 at the Broad Fourteens, and 131 gC·m -2 at the Oyster Grounds, of which 26 and 28%, respectively, could be attributed to sulphate reduction (assuming an annual sulphide reoxidation rate of 100%). Although sulphate reduction rates in the southern North Sea are higher than previously suggested, aerobic respiration is the most important pathway for benthic carbon mineralization at the stations visited. Production rates of benthic bacterial carbon measured with labelled leucine were much higher than carbon mineralization rates based on oxygen uptake or sulphate reduction. This may either imply a very high bacterial carbon conversion efficiency, or point to shortcomings in the accuracy of the techniques. A critical evaluation of the techniques is recommended.

  8. An evaluation of benthic community measures using laboratory-derived sediment effect concentrations

    SciTech Connect

    Dwyer, F.J.; Canfield, T.J.; Ingersoll, C.G.; Kemble, N.E.; Mount, D.R.

    1995-12-31

    Sediment effect concentrations (SECs) are contaminant sediment concentrations which are frequently associated with sediment toxicity. Recently, a number of different SECs have been calculated from laboratory toxicity tests with field collected sediments using Chironomus tentans, Chironomus riparius, and Hyalella azteca. Toxicity endpoints included (depending upon species) lethality, growth and sexual maturation. The authors selected the Effect Range Median (ERM) calculated for 28-d Hyalella azteca as an SEC for evaluating six different benthic community measures as indicators of contaminated sediment. The benthic measures included: taxa richness, chironomid genera richness, percent chironomid deformity, chironomid biotic index, ratio of chironomids/oligochaetes, and oligochaete biotic index. Benthic measures were obtained for 31 stations from the Great Lakes and 13 stations from Milltown Reservoir and Clark Fork River, MT. Each benthic measure was ranked from 1 to 100 and individual ranks and various combinations of ranks were plotted against the ratio of chemical concentration at the site/ERM calculated for that chemical (similar to a toxic unit approach) and the sum of the ERM ratios (sum of toxic units). Preliminary analysis indicates that, in general, benthic measures varied widely in relatively uncontaminated stations, confounding any underlying relationship that may have existed. The absence of chironomids, in areas with suitable habitat, seems to be indicative of grossly contaminated stations, but not an endpoint useful for discriminating stations with contaminant concentrations closer to the SEC. The usefulness of benthic measures as diagnostic tools for contaminated sediments and potential ways to improve these measures will be discussed.

  9. Associations between degraded benthic communities and contaminated sediments: Sabine Lake, Lake Pontchartrain, and Choctawhatchee Bay

    SciTech Connect

    Engle, V.D.; Summers, J.K.; Macauley, J.M.

    1994-12-31

    The Environmental Monitoring and Assessment Program for Estuaries (EMAP-E) in the Gulf of Mexico supplements its base sampling effort each year with localized, intensive spatial sampling in selected large estuarine systems. By selecting random locations within 70 km{sup 2} hexagonal areas, individual estuaries were sampled using EMAP methods but at four times the density as base sampling. In 1992, 19 sites were sampled in Lake Pontchartrain, Louisiana. In 1 993, 18 sites were sampled in Sabine Lake, Texas and 12 sites were sampled in Choctawhatchee Bay, Florida. At all sites, sediment grabs were taken and analyzed for benthic species composition and abundance, for toxicity to Ampelisca, and for organic and inorganic sediment contaminants. An indicator of biotic integrity, the benthic index, was calculated to represent the status of benthic communities. A series of statistical techniques, such as stepwise regression analysis, were employed to determine whether the variation in the benthic index could be associated with variation in sediment contaminants, sediment toxicity, or levels of dissolved oxygen. Spatial distributions of these parameters were examined to determine the geographical co-occurrence of degraded benthic communities and environmental stressors. In Lake Pontchartrain, for example, 85% of the variation in the benthic index was associated with decreased levels of dissolved oxygen, and increased concentrations of PCBs, alkanes, copper, tin, and zinc in the sediments.

  10. Assessment of the direct effects of biogenic and petrogenic activated carbon on benthic organisms.

    PubMed

    Lillicrap, Adam; Schaanning, Morten; Macken, Ailbhe

    2015-03-17

    Activated carbon (AC) has long been associated with the capacity to effectively remove organic substances from aquatic and sediment matrices; however, its use in remediation purposes has drawn some concern due to possible impacts on benthic communities. Within the inner Oslofjord, the use of AC has been well documented for reducing the risks associated with dioxins or dioxin-like compounds from contaminated areas. However, benthic surveys performed on areas treated with AC have revealed that the abundance of organisms inhabiting these areas can be reduced significantly in the subsequent years following treatment. The reason for the reduction in the benthic communities is currently unknown, and therefore, an integrated approach to assess the effects of 2 different forms of AC (biogenic and petrogenic) on benthic organisms has been performed. A battery of 3 different benthic organisms with different feeding and life-cycle processes has been used encompassing sediment surface feeders, sediment ingestors, and sediment reworkers. Results of the tests indicated that although AC is not acutely toxic at concentrations up to 1000 mg/L, there may be physical effects of the substance on benthic dwelling organisms at environmentally relevant concentrations of AC at remediated sites.

  11. Metal contamination in benthic macroinvertebrates in a sub-basin in the southeast of Brazil.

    PubMed

    Chiba, W A C; Passerini, M D; Tundisi, J G

    2011-05-01

    Benthic macroinvertebrates have many useful properties that make possible the use of these organisms as sentinel in biomonitoring programmes in freshwater. Combined with the characteristics of the water and sediment, benthic macroinvertebrates are potential indicators of environmental quality. Thus, the spatial occurrence of potentially toxic metals (Al, Zn, Cr, Co, Cu, Fe, Mn and Ni) in the water, sediment and benthic macroinvertebrates samples were investigated in a sub-basin in the southeast of Brazil in the city of São Carlos, São Paulo state, with the aim of verifying the metals and environment interaction with benthic communities regarding bioaccumulation. Hypothetically, there can be contamination by metals in the aquatic environment in the city due to lack of industrial effluent treatment. All samples were analysed by the USEPA adapted method and processed in an atomic absorption spectrophotometer. The sub-basin studied is contaminated by toxic metals in superficial water, sediment and benthic macroinvertebrates. The Bioaccumulation Factor showed a tendency for metal bioaccumulation by the benthic organisms for almost all the metal species. The results show a potential human and ecosystem health risk, contributing to metal contamination studies in aquatic environments in urban areas.

  12. Preliminary estimates of benthic fluxes of dissolved metals in Coeur d'Alene Lake, Idaho

    USGS Publications Warehouse

    Balistrieri, L.S.

    1998-01-01

    This report presents porewater and selected water column data collected from Coeur d'Alene Lake in September of 1992. Despite probable oxidation of the porewater samples during collection and handling, these data are used to calculate molecular diffusive fluxes of dissolved metals (that is, Zn, Pb, Cu, and Mn) across the sediment-water interface. While these data and calculations provide preliminary information on benthic metal fluxes in Coeur d'Alene Lake, further work is needed to verify their direction and magnitude. The benthic flux calculations indicate that the sediment is generally a source of dissolved Zn, Cu, Mn, and, possibly, Pb to the overlying water column. These benthic fluxes are compared with two other major sources of metals to Coeur d'Alene Lake-the Coeur d'Alene and St. Joe Rivers. Comparisons indicate that benthic fluxes of Zn, Pb, and Cu are generally less than half of the fluxes of these metals into the lake from the Coeur d'Alene River. However, in a few cases, the calculated benthic metal fluxes exceed the Coeur d'Alene River fluxes. Benthic fluxes of Zn and, possibly, Pb may be greater than the corresponding metal fluxes from the St. Joe River. These results have implications for changes in the relative importance of metal sources to the lake as remediation activities in the Coeur d'Alene River basin proceed.

  13. Invasive dreissenid mussels and benthic algae in Lake Michigan: characterizing effects on sediment bacterial communities.

    PubMed

    Lee, Philip O; McLellan, Sandra L; Graham, Linda E; Young, Erica B

    2015-01-01

    Dreissenid mussels have invaded the Laurentian Great Lakes causing dramatic changes to benthic-pelagic interactions. Despite research on food web impacts, there is limited data on mussel effects on benthic bacterial communities. This study examined effects of dreissenid mussels and benthic algae on sediment bacterial community composition and diversity. Triplicate experimental sediment plus lake water microcosms were used and either mussels, benthic algae or both were added. Changes in water nutrient chemistry and sediment bacterial communities were monitored using 16S rRNA amplicon sequencing, over 21 days. When mussels were present, nitrate and soluble reactive P increased significantly as the dominant N and P forms. Bacterial diversity increased in all microcosms, although bacterial community composition was distinct between treatment. Higher nitrate in mussel microcosms was accompanied by increases in nitrifying taxa (Nitrospira, Nitrosomonas), which are important in oxidizing mussel-excreted ammonium. Microcosms with algal additions showed increases in bacterial taxa capable of degrading algal cellulose, and Pelagibacter (SAR11) disappeared from all but control microcosms. This study suggests that bacterial communities in lake sediments respond to mussels and algae. Functional analysis of bacterial communities provides insights into changes in microbially mediated benthic nutrient transformations associated with invasive dreissenid mussels and benthic algae in lake ecosystems.

  14. Benthic Foraminifera in the Changing Ecosystem of Long Island Sound

    NASA Astrophysics Data System (ADS)

    Thaler, B.; Thomas, E.; Varekamp, J. C.

    2004-05-01

    Long Island Sound (LIS) is an estuary in a heavily urbanized region; Long Island lies to its South, New York City (NYC) to its West and Connecticut to its North. The Connecticut River contributes >70% of the fresh water influx. LIS has a narrow opening to the West (into East River), but exchange with the ocean occurs dominantly at its eastern end, resulting in an east-west gradient in salinity. An east-west gradient is also present in indicators of anthropogenic contamination in the surface sediments (e.g., trace metals) because western LIS is close to the major source of anthropogenic input (NYC). In addition, bottom currents focus fine-grained, contaminant-loaded sediments there. Since the early 1970's western LIS and parts of central LIS have suffered summer hypoxia, probably as a result of increased algal growth caused by anthropogenic nitrogen input. Benthic foraminifera are eukaryote heterotrophic organisms with a calcareous or agglutinated test. We investigated changes in their populations over time in about 2m-long gravity cores in westernmost (WLIS75GGC1; 73o 40'W, 40o 52'N, 19m waterdepth) and coastal central LIS (B1GGC1; 73o 4'W, 41o 10'N, 8m water depth), to document environmental changes over the last millennium, including the time of European settlement and the industrial revolution and population increase. An age model was derived from metal pollution records and 14C dating. Before European settlement, the low-diversity benthic faunas in core B1GGC1, at a depth within the zone of light penetration, were dominated by Elphidium excavatum, a species feeding on living diatoms. In western LIS (below the zone of light penetration) this species was less abundant and Elphidium incertum and Buccella frigida were common. In both cores, the absolute abundance of benthic foraminifera and the relative abundance of Elphidium excavatum increased in the early 1800's, coinciding with a time of rapid increase in human population around LIS and slightly before an

  15. Double Layers in Astrophysics

    NASA Technical Reports Server (NTRS)

    Williams, Alton C. (Editor); Moorehead, Tauna W. (Editor)

    1987-01-01

    Topics addressed include: laboratory double layers; ion-acoustic double layers; pumping potential wells; ion phase-space vortices; weak double layers; electric fields and double layers in plasmas; auroral double layers; double layer formation in a plasma; beamed emission from gamma-ray burst source; double layers and extragalactic jets; and electric potential between plasma sheet clouds.

  16. Boron in Pariette Wetland Sediments, Aquatic Vegetation & Benthic Organisms

    NASA Astrophysics Data System (ADS)

    Vasudeva, P.; Jones, C. P.; Powelson, D.; Jacobson, A. R.

    2015-12-01

    The Pariette Wetlands are comprised of 20 ponds located in Utah's Uintah Basin. Boron concentration in the Pariette Wetlands have been observed to exceed the total maximum daily limit of 750 µg L-1. Considering water flow in and out of the wetlands, boron is accumulating within the wetlands where it is sorbed to sediments and bioconcentrated by wetland plant and macro invertebrates. Since boron is an avian teratogen, an estimate of boron ingestion exposure is warranted. Samples from 3 of the 23 Pariette Wetland ponds with one pond near the inlet, one near the outlet, and one in the middle were collected. Five sampling points were designated along a 100 m transect of each pond. At each sampling point duplicate (or triplicate) samples of water, sediments, benthic organisms and wetland vegetation were collected. The sediments were collected with a KB-corer and divided at depths of 0-2 cm, 2-7 cm, and 7+ cm from the sediment surface. Sample splits were sent to the USU Bug lab for identification of invertebrate species. Whenever this transect was not intercepting vegetation, 2-3 additional sample sites were identified at the pond within stands of representative vegetation where bird nests are located. The plant parts used for boron analyses will include seeds, shoot and roots of vascular plants, as well as algae or duckweeds skimmed from the surface. Samples were processed within 2 days of collection. Water samples filtered through a 0.45 μ membrane filter were analyzed for DOC, pH and ECe. The dried and washed vegetation samples were ground and stored. The benthic organisms and macro invertebrates were netted at the water surface. The dried samples were weighed, ground and stored. Samples were weighed, oven dried and reweighed. For plant and macro-invertebrate samples, a nitric and hydrogen peroxide digestion procedure is used to dissolve environmentally available elements. The Hot Water extraction and DTPA-Sorbitol extraction were compared to estimate wetland plant

  17. Acoustic scattering by benthic and planktonic shelled animals.

    PubMed

    Stanton, T K; Chu, D; Wiebe, P H; Eastwood, R L; Warren, J D

    2000-08-01

    Acoustic backscattering measurements and associated scattering modeling were recently conducted on a type of benthic shelled animal that has a spiral form of shell (Littorina littorea). Benthic and planktonic shelled animals with this shape occur on the seafloor and in the water column, respectively, and can be a significant source of acoustic scattering in the ocean. Modeling of the scattering properties allows reverberation predictions to be made for sonar performance predictions as well as for detection and classification of animals for biological and ecological applications. The studies involved measurements over the frequency range 24 kHz to 1 MHz and all angles of orientation in as small as 1 degree increments. This substantial data set is quite revealing of the physics of the acoustic scattering by these complex shelled bodies and served as a basis for the modeling. Specifically, the resonance structure of the scattering was strongly dependent upon angle of orientation and could be traced to various types of rays (e.g., subsonic Lamb waves and rays entering the opercular opening). The data are analyzed in both the frequency and time domain (compressed pulse processing) so that dominant scattering mechanisms could be identified. Given the complexity of the animal body (irregular elastic shell with discontinuities), approximate scattering models are used with only the dominant scattering properties retained. Two models are applied to the data, both approximating the body as a deformed sphere: (1) an averaged form of the exact modal-series-based solution for the spherical shell, which is used to estimate the backscattering by a deformed shell averaged over all angles of orientation, and produces reasonably accurate predictions over all k1a(esr) (k1 is the acoustic wave number of the surrounding water and a(esr) is the equivalent spherical radius of the body), and (2) a ray-based formula which is used to estimate the scattering at fixed angle of orientation, but

  18. Polar Layers

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03581 Polar Layers

    This image shows just one example of the bright and dark markings that appear during summer time. The marks are related to the polar layers. If you happen to see a wild-eyed guy sticking his tongue out at you, you'll know why this image qualifies for the old 'art' category of THEMIS releases.

    Image information: VIS instrument. Latitude 80.6S, Longitude 34.1E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  19. Coupled effects of vertical mixing and benthic grazing on phytoplankton populations in shallow, turbid estuaries

    USGS Publications Warehouse

    Koseff, Jeffrey R.; Holen, Jacqueline K.; Monismith, Stephen G.; Cloern, James E.

    1993-01-01

    Coastal ocean waters tend to have very different patterns of phytoplankton biomass variability from the open ocean, and the connections between physical variability and phytoplankton bloom dynamics are less well established for these shallow systems. Predictions of biological responses to physical variability in these environments is inherently difficult because the recurrent seasonal patterns of mixing are complicated by aperiodic fluctuations in river discharge and the high-frequency components of tidal variability. We might expect, then, less predictable and more complex bloom dynamics in these shallow coastal systems compared with the open ocean. Given this complex and dynamic physical environment, can we develop a quantitative framework to define the physical regimes necessary for bloom inception, and can we identify the important mechanisms of physical-biological coupling that lead to the initiation and termination of blooms in estuaries and shallow coastal waters? Numerical modeling provides one approach to address these questions. Here we present results of simulation experiments with a refined version of Cloern's (1991) model in which mixing processes are treated more realistically to reflect the dynamic nature of turbulence generation in estuaries. We investigated several simple models for the turbulent mixing coefficient. We found that the addition of diurnal tidal variation to Cloern's model greatly reduces biomass growth indicating that variations of mixing on the time scale of hours are crucial. Furthermore, we found that for conditions representative of South San Francisco Bay, numerical simulations only allowed for bloom development when the water column was stratified and when minimal mixing was prescribed in the upper layer. Stratification, however, itself is not sufficient to ensure that a bloom will develop: minimal wind stirring is a further prerequisite to bloom development in shallow turbid estuaries with abundant populations of benthic

  20. Stimulating sediment bioremediation with benthic microbial fuel cells.

    PubMed

    Li, Wen-Wei; Yu, Han-Qing

    2015-01-01

    Efficient and sustainable technologies for cleaning up of contaminated sediments are under urgent demand. Bioremediation by utilizing the natural metabolic activities of sediment-inhabited microorganisms has been widely accepted as a viable option, but the relatively low efficiency and poor controllability severely limite its application. Here, we bring out the concept that electrochemical approaches may be used as an efficient means to stimulate sediment bioremediation. Although still at the very beginning, benthic microbial fuel cells (BMFC) as a remediation technology show many potential benefits, such as accelerated decontamination, self-sustained operation, relatively easy deployment and control, and environmental benignity. The unique features of BMFC setup and operation also give rise to substantially different challenges compared to conventional MFCs. In this review, we present a critical overview on the characteristics, possible application niches, and state-of-the-art progress of this technology. Especially, the current limitations in respect of system design, electrode selection, microbial control and selection of deployment environment are discussed in details, and the needed future research endeavors to promote its practical application are highlighted.

  1. Molar tooth carbonates and benthic methane fluxes in Proterozoic oceans.

    PubMed

    Shen, Bing; Dong, Lin; Xiao, Shuhai; Lang, Xianguo; Huang, Kangjun; Peng, Yongbo; Zhou, Chuanming; Ke, Shan; Liu, Pengju

    2016-01-01

    Molar tooth structures are ptygmatically folded and microspar-filled structures common in early- and mid-Proterozoic (∼2,500-750 million years ago, Ma) subtidal successions, but extremely rare in rocks <750 Ma. Here, on the basis of Mg and S isotopes, we show that molar tooth structures may have formed within sediments where microbial sulphate reduction and methanogenesis converged. The convergence was driven by the abundant production of methyl sulphides (dimethyl sulphide and methanethiol) in euxinic or H2S-rich seawaters that were widespread in Proterozoic continental margins. In this convergence zone, methyl sulphides served as a non-competitive substrate supporting methane generation and methanethiol inhibited anaerobic oxidation of methane, resulting in the buildup of CH4, formation of degassing cracks in sediments and an increase in the benthic methane flux from sediments. Precipitation of crack-filling microspar was driven by methanogenesis-related alkalinity accumulation. Deep ocean ventilation and oxygenation around 750 Ma brought molar tooth structures to an end. PMID:26739600

  2. Sensitivity of Heterogeneous Marine Benthic Habitats to Subtle Stressors

    PubMed Central

    Rodil, Iván F.; Lohrer, Andrew M.; Thrush, Simon F.

    2013-01-01

    It is important to understand the consequences of low level disturbances on the functioning of ecological communities because of the pervasiveness and frequency of this type of environmental change. In this study we investigated the response of a heterogeneous, subtidal, soft-sediment habitat to small experimental additions of organic matter and calcium carbonate to examine the sensitivity of benthic ecosystem functioning to changes in sediment characteristics that relate to the environmental threats of coastal eutrophication and ocean acidification. Our results documented significant changes between key biogeochemical and sedimentary variables such as gross primary production, ammonium uptake and dissolved reactive phosphorus flux following treatment additions. Moreover, the application of treatments affected relationships between macrofauna communities, sediment characteristics (e.g., chlorophyll a content) and biogeochemical processes (oxygen and nutrient fluxes). In this experiment organic matter and calcium carbonate showed persistent opposing effects on sedimentary processes, and we demonstrated that highly heterogeneous sediment habitats can be surprisingly sensitive to subtle perturbations. Our results have important biological implications in a world with relentless anthropogenic inputs of atmospheric CO2 and nutrients in coastal waters. PMID:24312332

  3. Potential Marine Benthic Habitat Map of Elkhorn Slough, California

    NASA Astrophysics Data System (ADS)

    Walton, K.; Garcia-Garcia, A.; Endris, C.

    2015-12-01

    While marine benthic habitat maps have been created for a big portion of California's coastline, the Elkhorn Slough Reserve lacks one. We have tentatively mapped its types of seafloor using a well-known classification system, which includes various types of large-scale and small-scale features, bottom induration, vegetation, surface texture, and slope. Seismic lines and sediment cores were collected to create the map. CSUMB's Seafloor Mapping Lab as well as the Elkhorn Slough National Estuarine Research Reserve provided bathymetry, raster files, and shapefiles to be incorporated into the project. We divided the Slough into three main sections: the Lower, Central, and Upper Slough. Sand sediments were found in the Lower Slough, which is a high-energy environment, whilst mud or silt sediments dominated the rest of the Slough. Five classification categories were used to describe the Slough's seafloor: flat sand sediments, sloped sand sediments, flat mud sediments, sloped mud sediments, and eelgrass on sandy sediment. Bathymetry data was used to discuss the Slough's sediment erosion and accretion. This preliminary map can be used to understand the location of various marine habitats, which is important for the wildlife conservation and planning efforts in the Slough. Acknowledgments: CSUMB (chirp), Ron Eby (ESNEER), Geoff (Triton Imaging Inc.). The Non-Senate Faculty Professional Development Award 19900-433332-ESGARC and ONR grant N00014-14-1-0172 supported this research.

  4. Optical Delineation of Benthic Habitat Using an Autonomous Underwater Vehicle

    SciTech Connect

    Moline, Mark A.; Woodruff, Dana L.; Evans, Nathan R.

    2007-06-01

    To improve understanding and characterization of coastal regions, there has been an increasing emphasis on autonomous systems that can sample the ocean on relevant scales. Autonomous underwater vehicles (AUVs) with active propulsion are especially well suited for studies of the coastal ocean because they are able to provide systematic and near-synoptic spatial observations. With this capability, science users are beginning to integrate sensor suits for a broad range of specific and often novel applications. Here, the relatively mature Remote Environmental Monitoring Units (REMUS) AUV system is configured with multi-spectral radiometers to delineate benthic habitat in Sequim Bay, WA. The vehicle was deployed in a grid pattern along 5 km of coastline in depths from 30 to less than 2 meters. Similar to satellite and/or aerial remote sensing, the bandwidth ratios from the downward looking radiance sensor and upward looking irradiance sensor were used to identify beds of eelgrass on sub-meter scales. Strong correlations were found between the optical reflectance signals and the geo-referenced in situ data collected with underwater video within the grid. Results demonstrate the ability of AUVs to map littoral habitats at high resolution and highlight the overall utility of the REMUS vehicle for nearshore oceanography.

  5. Modeling the effect of tides and waves on benthic biofilms

    NASA Astrophysics Data System (ADS)

    Mariotti, G.; Fagherazzi, S.

    2012-12-01

    We propose a simple model for growth of benthic biofilm subject to variable hydrodynamic disturbances and with a biofilm-dependent erodibility (biostabilization). Model results show that, for disturbances with equal intensity, the biofilm is eroded or not depending on its current biomass, which is a function of the past evolution trajectory. Because of the finite time needed for a biofilm to develop, both the intensity and frequency of periodical disturbances, such as tidal currents, determine whether the biofilm can approach its equilibrium biomass. Spring-neap tidal modulation favors biofilm development, since the reduction of the current shear stress associated with neap tides allows biofilm growth, thus increasing biostabilization and the biofilm's likelihood to withstand the subsequent energetic spring tides. On the other hand, diurnal tidal modulations are negative for biofilm development, because the diel biofilm growth is almost negligible. Under stochastic disturbances associated with wind waves, there are two most-likely states for the biofilm biomass: either close to zero or close to the equilibrium value, depending on wave intensity. If biostabilization is reduced or eliminated, the probability of intermediate values for biofilm biomass becomes also significant. The role of biostabilization is hence to exacerbate the probability of the end-member states. Finally, because of the nonmonotonic relationship between water depth and wave induced bed stresses, only extremely shallow and deep areas favor biofilm persistence. If light attenuation with depth is considered, deep water becomes unsuitable for biofilm growth when water turbidity is high.

  6. On the acoustic diffraction by the edges of benthic shells.

    PubMed

    Stanton, Timothy K; Chu, Dezhang

    2004-07-01

    Recent laboratory measurements of acoustic backscattering by individual benthic shells have isolated the edge-diffracted echo from echoes due to the surface of the main body of the shell. The data indicate that the echo near broadside incidence is generally the strongest for all orientations and is due principally to the surface of the main body. At angles well away from broadside, the echo levels are lower and are due primarily to the diffraction from the edge of the shell. The decrease in echo levels from broadside incidence to well off broadside is shown to be reasonably consistent with the decrease in acoustic backscattering from normal incidence to well off normal incidence by a shell-covered seafloor. The results suggest the importance of the edge of the shell in off-normal-incidence backscattering by a shell-covered seafloor. Furthermore, when considering bistatic diffraction by edges, there are implications that the edge of the shell (lying on the seafloor) can cause significant scattering in many directions, including at subcritical angles. PMID:15295983

  7. Li partitioning in the benthic foraminifera Amphistegina lessonii

    NASA Astrophysics Data System (ADS)

    Langer, Gerald; Sadekov, Aleksey; Thoms, Silke; Mewes, Antje; Nehrke, Gernot; Greaves, Mervyn; Misra, Sambuddha; Bijma, Jelle; Elderfield, Henry

    2015-12-01

    The shallow water benthic foraminifer Amphistegina lessonii was grown in seawater of variable Li and Ca concentration and shell Li/Ca was determined by means of LA-ICPMS. Shell Li/Ca is positively correlated to seawater Li/Ca only when the Li concentration of seawater is changed. If the seawater Ca concentration is changed, shell Li/Ca remains constant. This indicates that Li does not compete with Ca for incorporation in the shell of A. lessonii. A recently proposed calcification model can be applied to divalent cations (e.g., Mg and Sr), which compete for binding sites of ion transporters and positions in the calcite lattice. By contrast, the transport pathway of monovalent cations such as Li is probably diffusion based (e.g., ion-channels), and monovalent cations do not compete with Ca for a position in the calcite lattice. Here we present a new model for Li partitioning into foraminiferal calcite which predicts our experimental results and should also be applicable to other alkali metals.

  8. Standardising the assessment of Functional Integrity in benthic ecosystems

    NASA Astrophysics Data System (ADS)

    de Juan, Silvia; Hewitt, Judi; Thrush, Simon; Freeman, Debbie

    2015-04-01

    Ecological integrity is an overarching concept that integrates multiple properties of ecosystems, including structure, function and resilience to external change. We explore the links between ecological integrity and structural surrogates for ecosystem functioning to develop a cost-effective assessment of Functional Integrity for marine habitats based on biological traits, abundance and heterogeneity, focused on the visible components of the seafloor, i.e., epibenthic flora and fauna and seabed biogenic habitat features. The assessment was based on diversity and redundancy of functional traits of the identified benthic components, supplemented by estimates of spatial heterogeneity (habitat transitions) and vertical habitat complexity. This approach was developed using video data collected in different years with different sampling strategies in two locations: Kawau Bay in North Island of New Zealand, and Port Pegasus in Stewart Island, off South Island of New Zealand; this last location was a priori expected to be nearly-pristine. Despite variability in sampling techniques and environmental settings, the approach proved effective and evidenced higher measures of Functional Integrity in the Port Pegasus location. This study introduces a first step to measure ecological integrity by successfully converting video data to surrogates of Functional Integrity, in a way expected to be habitat independent.

  9. Molar tooth carbonates and benthic methane fluxes in Proterozoic oceans

    NASA Astrophysics Data System (ADS)

    Shen, Bing; Dong, Lin; Xiao, Shuhai; Lang, Xianguo; Huang, Kangjun; Peng, Yongbo; Zhou, Chuanming; Ke, Shan; Liu, Pengju

    2016-01-01

    Molar tooth structures are ptygmatically folded and microspar-filled structures common in early- and mid-Proterozoic (~2,500-750 million years ago, Ma) subtidal successions, but extremely rare in rocks <750 Ma. Here, on the basis of Mg and S isotopes, we show that molar tooth structures may have formed within sediments where microbial sulphate reduction and methanogenesis converged. The convergence was driven by the abundant production of methyl sulphides (dimethyl sulphide and methanethiol) in euxinic or H2S-rich seawaters that were widespread in Proterozoic continental margins. In this convergence zone, methyl sulphides served as a non-competitive substrate supporting methane generation and methanethiol inhibited anaerobic oxidation of methane, resulting in the buildup of CH4, formation of degassing cracks in sediments and an increase in the benthic methane flux from sediments. Precipitation of crack-filling microspar was driven by methanogenesis-related alkalinity accumulation. Deep ocean ventilation and oxygenation around 750 Ma brought molar tooth structures to an end.

  10. Molar tooth carbonates and benthic methane fluxes in Proterozoic oceans

    PubMed Central

    Shen, Bing; Dong, Lin; Xiao, Shuhai; Lang, Xianguo; Huang, Kangjun; Peng, Yongbo; Zhou, Chuanming; Ke, Shan; Liu, Pengju

    2016-01-01

    Molar tooth structures are ptygmatically folded and microspar-filled structures common in early- and mid-Proterozoic (∼2,500–750 million years ago, Ma) subtidal successions, but extremely rare in rocks <750 Ma. Here, on the basis of Mg and S isotopes, we show that molar tooth structures may have formed within sediments where microbial sulphate reduction and methanogenesis converged. The convergence was driven by the abundant production of methyl sulphides (dimethyl sulphide and methanethiol) in euxinic or H2S-rich seawaters that were widespread in Proterozoic continental margins. In this convergence zone, methyl sulphides served as a non-competitive substrate supporting methane generation and methanethiol inhibited anaerobic oxidation of methane, resulting in the buildup of CH4, formation of degassing cracks in sediments and an increase in the benthic methane flux from sediments. Precipitation of crack-filling microspar was driven by methanogenesis-related alkalinity accumulation. Deep ocean ventilation and oxygenation around 750 Ma brought molar tooth structures to an end. PMID:26739600

  11. Underwater locomotion strategy by a benthic pennate diatom Navicula sp.

    PubMed

    Wang, Jiadao; Cao, Shan; Du, Chuan; Chen, Darong

    2013-10-01

    The mechanism of diatom locomotion has been widely researched but still remains a hypothesis. There are several questionable points on the prevailing model proposed by Edgar, and some of the observed phenomena cannot be completely explained by this model. In this paper, we undertook detailed investigations of cell structures, locomotion, secreted mucilage, and bending deformation for a benthic pennate diatom Navicula species. According to these broad evidences, an updated locomotion model is proposed. For Navicula sp., locomotion is realized via two or more pseudopods or stalks protruded out of the frustules. The adhesion can be produced due to the pull-off of one pseudopod or stalk from the substratum through extracellular polymeric substances. And the positive pressure is generated to balance the adhesion because of the push-down of another pseudopod or stalk onto the substratum. Because of the positive pressure, friction is generated, acting as a driving force of locomotion, and the other pseudopod or stalk can detach from the substratum, resulting in the locomotion. Furthermore, this model is validated by the force evaluation and can better explain observed phenomena. This updated model would provide a novel aspect on underwater locomotion strategy, hence can be useful in terms of artificial underwater locomotion devices.

  12. Layered Fan

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Context image for PIA03692 Layered Fan

    This beautiful fan deposit is located at the end of a mega-gully that empties into the southern trough of Coprates Chasma.

    Image information: VIS instrument. Latitude -14.9N, Longitude 299.8E. 17 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  13. Ecological periodic tables for benthic macrofaunal usage of estuarine habitats: Insights from a case study in Tillamook Bay, Oregon, USA

    NASA Astrophysics Data System (ADS)

    Ferraro, Steven P.; Cole, Faith A.

    2012-05-01

    This study validates the ecological relevance of estuarine habitat types to the benthic macrofaunal community and, together with previous similar studies, suggests they can serve as elements in ecological periodic tables of benthic macrofaunal usage in the bioregion. We compared benthic macrofaunal Bray-Curtis similarity and the means of eight benthic macrofaunal community measures across seven habitat types in Tillamook Bay, Oregon, USA: intertidal eelgrass (Zostera marina), dwarf eelgrass (Zostera japonica), oyster (Crassostrea gigas) ground culture, burrowing mud shrimp (Upogebia pugettensis), burrowing ghost shrimp (Neotrypaea californiensis), sand and subtidal. Benthic macrofaunal Bray-Curtis similarity differed among all the habitats except ghost shrimp and sand. The habitat rank order on mean benthic macrofaunal species richness, abundance and biomass was dwarf eelgrass ≈ oyster ≥ mud shrimp ≈ eelgrass > sand ≈ ghost shrimp ≈ subtidal. The benthic macrofaunal habitat usage pattern in Tillamook Bay was, with a few exceptions, similar to that in two other US Pacific Northwest estuaries. The exceptions indicate variants of eelgrass and ghost shrimp habitat that differ in benthic macrofaunal usage perhaps due to differences in the coarseness of the sand fraction of the sediments in which they live. The similarities indicate periodic benthic macrofaunal usage patterns across the other habitat types extend over a wider geographic scale and range of environmental conditions than previously known.

  14. Assessment of toxicity thresholds in aquatic environments: does benthic growth of diatoms affect their exposure and sensitivity to herbicides?

    PubMed

    Larras, Floriane; Montuelle, Bernard; Bouchez, Agnès

    2013-10-01

    Benthic diatoms evolved in a biofilm structure, at the interface between water and substrata. Biofilms can adsorb toxicants, such as herbicides, but little is known about the exposure of biofilm organisms, such as benthic diatoms, to these adsorbed herbicides. We assessed the sensitivity of 11 benthic diatoms species to 6 herbicides under both planktonic and benthic conditions using single-species bioassays. The concentration that reduced the growth rate of the population by 10% (EC10) and 50% (EC50), respectively, varied depending on the species, the herbicides, and the growth forms involved. As a general trend, the more hydrophobic the herbicide, the more species were found to be sensitive under benthic growth conditions. Statistical differences (alpha<5%) were observed between the sensitivities under planktonic and benthic growth conditions for many hydrophobic herbicides. A protective effect of the biofilm against herbicides was observed, and this tended to decrease (at both the EC10 and EC50 levels) with increasing hydrophobicity. The biofilm matrix appeared to control exposure to herbicides, and consequently their toxicity towards benthic diatoms. For metolachlor, terbutryn and irgarol, benthic thresholds derived from species sensitivity distributions were more protective than planktonic thresholds. For hydrophobic herbicides, deriving sensitivity thresholds from data obtained under benthic growth seems to offer a promising alternative.

  15. Effects of N and P enrichment on competition between phytoplankton and benthic algae in shallow lakes: a mesocosm study.

    PubMed

    Zhang, Xiufeng; Mei, Xueying; Gulati, Ramesh D; Liu, Zhengwen

    2015-03-01

    Competition for resources between coexisting phytoplankton and benthic algae, but with different habitats and roles in functioning of lake ecosystems, profoundly affects dynamics of shallow lakes in the process of eutrophication. An experiment was conducted to test the hypothesis that combined enrichment with nitrogen (N) and phosphorus (P) would be a greater benefit to phytoplankton than benthic algae. The growth of phytoplankton and benthic algae was measured as chlorophyll a (Chl a) in 12 shallow aquatic mesocosms supplemented with N, P, or both. We found that enrichment with N enhanced growth of benthic algae, but not phytoplankton. P enrichment had a negative effect on benthic algal growth, and no effect on the growth of phytoplankton. N+P enrichment had a negative effect on benthic algae, but enhanced the growth of phytoplankton, thus reducing the proportion of benthic algae contributing to the combined biomass of these two groups of primary producers. Thus, combined N+P enrichment is more favorable to phytoplankton in competition with benthic algae than enrichment with either N or P alone. Our study indicates that combined enrichment with N+P promotes the dominance of phytoplankton over benthic algae, with consequences for the trophic dynamics of shallow lake ecosystems.

  16. The role of the benthic-hyporheic zone in controlling nitrous oxide emissions along two stream networks draining watersheds with contrasting land use

    NASA Astrophysics Data System (ADS)

    Marzadri, Alessandra; Dee, Martha M.; Tonina, Daniele; Tank, Jennifer L.; Bellin, Alberto

    2016-04-01

    Nitrous oxide (N2O) is a potent greenhouse gas responsible of stratospheric ozone destruction. Denitrification in stream ecosystems occurs within the benthic layer at the sediment-water interface and within subsurface environments such as the hyporheic zone and results in N2O production that could be eventually emitted to the atmosphere. Here, we quantify the role of benthic and hyporheic zones as sources of N2O gas and explore the dependence of emissions from stream morphology, flow hydraulics, land use and climate using a recently-developed fully analytical framework. Variations in N2O emissions within and among catchments of contrasting land use can be explained with a new denitrification Damköhler number (DaD) that accounts for denitrification processes within both benthic and hyporheic zones. For initial model development, we found a strong relationship between DaD and stream N2O emissions using field data collected from multiple headwater streams (i.e., LINXII project) from different biomes draining contrasting land use. We then tested its generality by comparing N2O emissions predicted with DaD to those measured using a synoptic sampling campaign in two stream networks draining contrasting land use: Manistee R (Michigan, USA) and Tippecanoe R (Indiana, USA). Our dimensionless analysis shows that the effect of land use disappears after making the emissions dimensionless with respect to the nitrogen load. Reliable predictions of N2O emissions at the stream network scale can be obtained from a limited amount of information, consisting in relatively easy to obtain biogeochemical and hydromorphological quantities.

  17. Quantifying benthic nitrogen fluxes in Puget Sound, Washington: a review of available data

    USGS Publications Warehouse

    Sheibley, Richard W.; Paulson, Anthony J.

    2014-01-01

    Understanding benthic fluxes is important for understanding the fate of materials that settle to the Puget Sound, Washington, seafloor, as well as the impact these fluxes have on the chemical composition and biogeochemical cycles of marine waters. Existing approaches used to measure benthic nitrogen flux in Puget Sound and elsewhere were reviewed and summarized, and factors for considering each approach were evaluated. Factors for selecting an appropriate approach for gathering information about benthic flux include: availability of resources, objectives of projects, and determination of which processes each approach measures. An extensive search of literature was undertaken to summarize known benthic nitrogen fluxes in Puget Sound. A total of 138 individual flux chamber measurements and 38 sets of diffusive fluxes were compiled for this study. Of the diffusive fluxes, 35 new datasets were located, and new flux calculations are presented in this report. About 65 new diffusive flux calculations are provided across all nitrogen species (nitrate, NO3-; nitrite, NO2-; ammonium, NH4+). Data analysis of this newly compiled benthic flux dataset showed that fluxes beneath deep (greater than 50 meters) water tended to be lower than those beneath shallow (less than 50 meters) water. Additionally, variability in flux at the shallow depths was greater, possibly indicating a more dynamic interaction between the benthic and pelagic environments. The overall range of bottom temperatures from studies in the Puget Sound area were small (5–16 degrees Celsius), and only NH4+ flux showed any pattern with temperature. For NH4+, flux values and variability increased at greater than about 12 degrees Celsius. Collection of additional study site metadata about environmental factors (bottom temperature, depth, sediment porosity, sediment type, and sediment organic matter) will help with development of a broader regional understanding benthic nitrogen flux in the Puget Sound.

  18. Determining the relative sensitivity of benthic diatoms to atrazine using rapid toxicity testing: a novel method.

    PubMed

    Wood, Rebecca J; Mitrovic, Simon M; Kefford, Ben J

    2014-07-01

    Herbicides pose a potential threat to aquatic ecosystems, especially to phototrophic organisms such as benthic diatoms. Benthic diatoms may be a valuable indicator of the toxic impacts of herbicides in aquatic systems. However, this requires information on the herbicide sensitivity of a wide range of freshwater benthic diatom taxa. Unfortunately this information is only available for a limited number of species as current methods of developing new algae toxicity tests on individual taxa are lengthy and costly. To address this issue, we developed a new rapid toxicity test method to test natural benthic communities, from which the relative herbicide sensitivity of many individual taxa can be derived. This involved the collection of natural benthic communities from rocks in situ, which were placed directly into laboratory toxicity tests. Sensitivity data for several diatom genera in a 48 hour exposure toxicity test were produced, without the need for cultures or multiple site visits. After exposure to the highest treatment of atrazine (500 μg L(-1)) there were significant declines of healthy cells in the most sensitive genera: Gomphonema declined by 74%, Amphora by 62%, Cymbella by 54% and Ulnaria by 34% compared to control levels. In contrast, the genera, Eunotia, Achnanthidium and Navicula, had no statistically significant decline in cell health. This method can identify the diatom taxa most at risk of herbicide toxicity within the natural benthic diatom community. The rapid toxicity testing method presented is a simple and effective method to obtain sensitivity data for multiple taxa within a natural benthic diatom community in a relatively short period of time.

  19. Spatial-temporal feeding dynamics of benthic communities in an estuary-marine gradient

    NASA Astrophysics Data System (ADS)

    Antonio, Emily S.; Kasai, Akihide; Ueno, Masahiro; Ishihi, Yuka; Yokoyama, Hisashi; Yamashita, Yoh

    2012-10-01

    We investigated the fluctuations of carbon and nitrogen stable isotope ratios in benthic consumers and their potential food sources to determine the spatial and temporal variations in the utilization of available organic matter, indicating the origin and pathways of energy from Yura Estuary to Tango Sea, Japan. Field samplings were conducted from the upper estuary to offshore with sampling frequency of twice per season from April (spring) 2006 to February (winter) 2007. The δ13C signatures of the upper and lower estuary benthos showed depleted and in wide range (-28.9‰ to -13.5‰) compared to the enriched and within narrow range signatures of marine benthos (-20.6‰ to -14.0‰) in all seasons. On the contrary, the δ15N signatures of benthic communities showed decreasing trend seaward and summer values were different from the other seasons. Using the dual isotope and multisource mixing models, we estimated the relative contributions of potential food sources to the benthos diet. River POM played an important source of energy for the estuarine benthos, especially in winter when river discharge was high. Marine POM served as an important alternative food for the estuarine benthos from spring to autumn when seawater intruded the bottom estuary. Benthic microalgae were the major food source at the shallow coast throughout the year, while marine POM fueled the deep coast and offshore benthic food webs. Spatial and temporal feeding variations in estuarine benthic communities were driven by the hydrology of the estuary, whereas primary production and transport of food source dictated diet variations of marine benthic communities. The elucidation of the dynamic energy subsidy among aquatic systems highlights the importance of the land-sea transition zones that is crucial for benthic secondary productions.

  20. Long-term benthic infaunal monitoring at a deep-ocean dredged material disposal site off Northern California

    NASA Astrophysics Data System (ADS)

    Blake, James A.; Maciolek, Nancy J.; Ota, Allan Y.; Williams, Isabelle P.

    2009-09-01

    One hundred and thirty-five benthic infaunal samples were collected from the San Francisco Deep-Ocean Disposal Site (SF-DODS) over a 10-year period from January 1996 to September 2004. Each sample was 0.1 m 2, cut to a depth of 10 cm, and sieved through a 300-μm mesh. A total of 810 species of benthic invertebrates were identified; the majority of taxa (65.4%) new to science. The fauna represents a rich lower slope infaunal assemblage that rivals similarly studied locations in the western North Atlantic. No regional impact or degradation of benthic infauna due to dredged material disposal was detected. All reference stations and stations on the site boundary maintained high species richness and diversity during the monitoring period. Exceptions included an occasional sample with anomalously high numbers of one or two species that reduced the diversity and/or equitability. Within SF-DODS species richness and diversity were often reduced. Stations within the disposal site were recolonized by the same taxa that normally occurred in adjacent reference areas. Initial colonizers of fresh dredged material included spionid and paraonid polychaetes that were typical dominants at the site. At least one polychaete species, Ophelina sp. 1, sometimes colonized dredged materials containing coarse sand. One sample at Station 13, located in the middle of SF-DODS (September 2002), contained 57 species of benthic invertebrates, suggesting that colonization of fresh dredged material is rapid. It seems unlikely that larval dispersal and settlement account for this rapid recolonization; therefore it is postulated that adult organisms from adjacent areas move to the disturbed sites via boundary layer currents. The steep continental slope adjacent to SF-DODS is subject to turbidity flows and the resident fauna are likely pre-adapted to rapidly colonize disturbed sediments. Larval dispersal, especially by spionid polychaetes such as Prionospio delta, may also be important in colonizing

  1. Core layering

    NASA Astrophysics Data System (ADS)

    Jacobson, S. A.; Rubie, D. C.; Hernlund, J. W.; Morbidelli, A.

    2015-12-01

    We have created a planetary accretion and differentiation model that self-consistently builds and evolves Earth's core. From this model, we show that the core grows stably stratified as the result of rising metal-silicate equilibration temperatures and pressures, which increases the concentrations of light element impurities into each newer core addition. This stable stratification would naturally resist convection and frustrate the onset of a geodynamo, however, late giant impacts could mechanically mix the distinct accreted core layers creating large homogenous regions. Within these regions, a geodynamo may operate. From this model, we interpret the difference between the planetary magnetic fields of Earth and Venus as a difference in giant impact histories. Our planetary accretion model is a numerical N-body integration of the Grand Tack scenario [1]—the most successful terrestrial planet formation model to date [2,3]. Then, we take the accretion histories of Earth-like and Venus-like planets from this model and post-process the growth of each terrestrial planet according to a well-tested planetary differentiation model [4,5]. This model fits Earth's mantle by modifying the oxygen content of the pre-cursor planetesimals and embryos as well as the conditions of metal-silicate equilibration. Other non-volatile major, minor and trace elements included in the model are assumed to be in CI chondrite proportions. The results from this model across many simulated terrestrial planet growth histories are robust. If the kinetic energy delivered by larger impacts is neglected, the core of each planet grows with a strong stable stratification that would significantly impede convection. However, if giant impact mixing is very efficient or if the impact history delivers large impacts late, than the stable stratification can be removed. [1] Walsh et al. Nature 475 (2011) [2] O'Brien et al. Icarus 223 (2014) [3] Jacobson & Morbidelli PTRSA 372 (2014) [4] Rubie et al. EPSL 301

  2. Assessment of net community production and calcification of a coral reef using a boundary layer approach

    NASA Astrophysics Data System (ADS)

    Takeshita, Yuichiro; McGillis, Wade; Briggs, Ellen M.; Carter, Amanda L.; Donham, Emily M.; Martz, Todd R.; Price, Nichole N.; Smith, Jennifer E.

    2016-08-01

    Coral reefs are threatened worldwide, and there is a need to develop new approaches to monitor reef health under natural conditions. Because simultaneous measurements of net community production (NCP) and net community calcification (NCC) are used as important indicators of reef health, tools are needed to assess them in situ. Here we present the Benthic Ecosystem and Acidification Measurement System (BEAMS) to provide the first fully autonomous approach capable of sustained, simultaneous measurements of reef NCP and NCC under undisturbed, natural conditions on time scales ranging from tens of minutes to weeks. BEAMS combines the chemical and velocity gradient in the benthic boundary layer to quantify flux from the benthos for a variety of parameters to measure NCP and NCC. Here BEAMS was used to measure these rates from two different sites with different benthic communities on the western reef terrace at Palmyra Atoll for 2 weeks in September 2014. Measurements were made every ˜15 min. The trends in metabolic rates were consistent with the benthic communities between the two sites with one dominated by fleshy organisms and the other dominated by calcifiers (degraded and healthy reefs, respectively). This demonstrates the potential utility of BEAMS as a reef health monitoring tool. NCP and NCC were tightly coupled on time scales of minutes to days, and light was the primary driver for the variability of daily integrated metabolic rates. No correlation between CO2 levels and daily integrated NCC was observed, indicating that NCC at these sites were not significantly affected by CO2.

  3. In Situ Boundary Layer Coral Metabolism in the Atlantic Ocean Acidification Test Bed

    NASA Astrophysics Data System (ADS)

    McGillis, Wade

    2013-04-01

    and Chris Langdon, Brice Loose, Dwight Gledhill, Diana Hsueh, Derek Manzello, Ian Enochs, Ryan Moyer We present net ecosystem productivity (nep) and net ecosystem calcification (nec) in coral and seagrass ecosystems using the boundary layer gradient flux technique (CROSS). Coastal anthropogenic inputs and changes in global ocean chemistry in response to rising levels of atmospheric carbon dioxide has emerged in recent years as a topic of considerable concern. Coral reefs are particularly vulnerable from eroded environmental conditions including ocean acidification and water pollution. The Atlantic Ocean Acidification Testbed (AOAT) project monitors metabolism to ascertain the continuing health of coral reef ecosystems. The CROSS boundary layer nep/nec approach is one component of this diagnostic program. Certification of CROSS as an operational monitoring tool is underway in the AOAT. CROSS inspects a benthic community and measures productivity/respiration and calcification/dissolution over an area of 10 square meters. Being a boundary layer tool, advection and complex mesoscale flows are not a factor or concern and CROSS is autonomous and can be used at deep benthic sites. The interrogation area is not enclosed therefore exposed to ambient light, flow, and nutrient levels. CROSS is easy to deploy, unambiguous, and affordable. Repeated measurements have been made from 2011-2012 in reefal systems in La Parguera Puerto Rico and the Florida Keys, USA. Diurnal, seasonal and regional metabolism will be compared and discussed. The ability to accurately probe benthic ecosystems provides a powerful management and research tool to policy makers and researchers.

  4. Towards an integrated view of benthic and pelagic processes in the southern North Sea (German Bight)

    NASA Astrophysics Data System (ADS)

    Friedrich, Jana; van Beusekom, Justus; Neumann, Andreas; Naderipour, Celine

    2015-04-01

    The North Sea can be classified as a semi-enclosed shelf on the western-European continent. Atlantic influences are mainly through the Fair Isle current Channel in the North, and through the Strait of Dover in the South. An anti-clockwise circulation prevails, driven by mainly semi-diurnal tides and winds. The German Bight is located in the south-eastern part of the North Sea, and is strongly influenced by continental rivers. The outflow from the rivers Scheldt, Maas and Rhine is carried towards the German Bight with the residual currents. The German rivers Ems, Weser and Elbe directly debouche into the German Bight. On the shallow shelf, the water column is completely mixed by tidal forces and wind, largely preventing downward flux of particles and instead fostering temporary deposition and resuspension, which influences benthic mineralization. Hence, complex interactions between pelagic and benthic processes occur. Previous budget calculations indicate that the nutrient inventory has to be processed several times to support observed primary production, and, depending on water depth; only 10-20% remineralisation occurs in sediments of the German Bight whereas about 50% of organic matter is remineralised in the sediments of the shallow Wadden Sea. In this presentation, we use in-situ and ex-situ field data on pelagic and benthic oxygen respiration and benthic nutrient fluxes to assess the intense mineralization activity in the German Bight, the partitioning of benthic and pelagic processes and the factors influencing organic matter mineralization. Measurements of pelagic oxygen respiration based on Winkler titration, in-situ benthic oxygen uptake measurements based on flux-chamber landers and ex-situ incubations of intact sediment cores revealed that benthic remineralisation rates are about an order of magnitude smaller than pelagic rates, in agreement with previous budget estimates. Both benthic and pelagic oxygen respiration show a strong seasonality; with higher

  5. Benthic substrate classification map: Gulf Islands National Seashore

    USGS Publications Warehouse

    Lavoie, Dawn; Flocks, James; Twichell, Dave; Rose, Kate

    2013-01-01

    Island. Prevailing sediment transport processes will provide natural renourishment of the westward islands in the barrier system (U.S. Army Corps of Engineers, 2009b). One difficulty in developing the final recommendations is that few data are available to incorporate into restoration plans related to bathymetry, sediment type, and biota. For example, the most recent bathymetry available dates to when East and West Ship Islands were a single continuous island (1917). As a result, the MsCIP program has encouraged post-hurricane bathymetric data collection for future reference. Furthermore, managing a complex environment such as this barrier island system for habitat conservation and best resource usage requires significant knowledge about those habitats and resources. To effectively address these issues, a complete and comprehensive understanding of the type, geographic extent, and condition of marine resources included within the GUIS is required. However, the data related to the GUIS marine resources are limited either spatially or temporally. Specifically, there is limited knowledge and information about the distribution of benthic habitats and the characteristics of the offshore region of the GUIS, even though these are the habitats that will be most affected by habitat restoration. The goal of this project is to develop a comprehensive map of the benthic marine habitats within the GUIS to give park managers the ability to develop strategies for coastal and ocean-resource management and to aid decisionmakers in evaluating conservation priorities.

  6. Benthic foraminiferal assemblages reveal the history of the Burdigalian Seaway

    NASA Astrophysics Data System (ADS)

    Piller, W. E.; Grunert, P.; Harzhauser, M.

    2013-12-01

    The opening and closure of seaways have immanent paleoclimatic, paleoceanographic and paleobiogeographic consequences as they determine the exchange of water masses. During the Oligocene to Miocene severe alterations of marine gateway configuration shaped the evolution of the Mediterranean - Paratethys region. From early to middle Burdigalian (20.4-17.5 Myrs) the Burdigalian Seaway connected the western Mediterranean Sea with the Central Paratethys Sea via the North Alpine Foreland Basin (NAFB). Its evolution resulted in profound paleoceanograpic and -geographic changes, and initiated a wave of faunal immigration from the Atlantic and Mediterranean into the Paratethys that had a severe impact on marine ecosystems. A detailed Early Miocene proxy record integrating seismic images, microfossil assemblages and geochemical analyses has been recently established for the Puchkirchen Basin (PB) as part of the NAFB. Herein, we exemplarily show the reconstruction of the dynamic early to middle Burdigalian paleoenvironment based on a quantitative evaluation of benthic foraminiferal assemblages from drill-sites and outcrops. Four major phases in PB development are distinguished, and new stratigraphic constraints allow discussing the results in the context of the evolution of the Burdigalian Seaway: 1. The global early Burdigalian sea-level rise initiated a marine transgression in the NAFB. In the PB, a long-lived basin-axial channel system was reactivated resulting in turbiditic and mass-flow deposition. The unstable upper bathyal environment is reflected in a low diverse autochthonous benthic foraminiferal fauna mainly composed of Bathysiphon filiformis. 2. The perpetuating transgression flooded large shelf areas and established the Burdigalian Seaway. The channel belt was cut off from its sediment sources and shut down. Subsequently, sedimentation was controlled by episodic turbidites from the southern basin margin, and large NE prograding delta fans. High sedimentation

  7. Predicting ecological changes on benthic estuarine assemblages through decadal climate trends along Brazilian Marine Ecoregions

    NASA Astrophysics Data System (ADS)

    Bernardino, Angelo F.; Netto, Sérgio A.; Pagliosa, Paulo R.; Barros, Francisco; Christofoletti, Ronaldo A.; Rosa Filho, José S.; Colling, André; Lana, Paulo C.

    2015-12-01

    Estuaries are threatened coastal ecosystems that support relevant ecological functions worldwide. The predicted global climate changes demand actions to understand, anticipate and avoid further damage to estuarine habitats. In this study we reviewed data on polychaete assemblages, as a surrogate for overall benthic communities, from 51 estuaries along five Marine Ecoregions of Brazil (Amazonia, NE Brazil, E Brazil, SE Brazil and Rio Grande). We critically evaluated the adaptive capacity and ultimately the resilience to decadal changes in temperature and rainfall of the polychaete assemblages. As a support for theoretical predictions on changes linked to global warming we compared the variability of benthic assemblages across the ecoregions with a 40-year time series of temperature and rainfall data. We found a significant upward trend in temperature during the last four decades at all marine ecoregions of Brazil, while rainfall increase was restricted to the SE Brazil ecoregion. Benthic assemblages and climate trends varied significantly among and within ecoregions. The high variability in climate patterns in estuaries within the same ecoregion may lead to correspondingly high levels of noise on the expected responses of benthic fauna. Nonetheless, we expect changes in community structure and productivity of benthic species at marine ecoregions under increasing influence of higher temperatures, extreme events and pollution.

  8. Benthic invertebrate population characteristics as affected by water quality in coal-bearing regions of Tennessee

    USGS Publications Warehouse

    Bradfield, A.D.

    1986-01-01

    Benthic invertebrate and water quality data collected during previous U.S. Geological Survey studies to provide background hydrologic information on streams draining Tennessee coal reserves, were evaluated to identify possible relations between stream biota and water quality. Linear regressions produced low correlation coefficients relating the number of taxa/sample, total number of organisms/sample, sample diversity, and percentage composition of selected orders of invertebrates, with average water quality parameter values available at sampling stations (r is < 0.62 at p=0.05). Analyses of these data by linear regressions explained little of the variability in benthic invertebrate samples primarily because the distributions of benthic organisms along environmental gradients are nonlinear. Variability in substrate characteristics in the study area and seasonal insect emergence patterns also complicated interpretation of these data. However, analysis of variance tests did indicate significant trends towards reduced number of taxa, number of organisms, and sample diversity at stations with relatively poor water quality conditions. Decreasing percentage composition of Ephemeroptera was generally accompanied by an increase in percent Diptera at stations with higher water quality constituent concentrations and acidic pH ( > than 0.6 units). These trends indicate significant differences in benthic communities at sites with evidence of more severe land use impacts. Additional data on benthic invertebrates, water quality , and physical habitat conditions, along with analyses of data using multivariate statistical methods are needed to define ecological relations between specific groups of invertebrates and environmental conditions. (Author 's abstract)

  9. Decadal-scale effects of benthic habitat and marine reserve protection on Philippine goatfish (F: Mullidae)

    NASA Astrophysics Data System (ADS)

    Russ, Garry R.; Bergseth, Brock J.; Rizzari, Justin R.; Alcala, Angel C.

    2015-09-01

    Reef fish populations can be affected by both fishing and changes in benthic habitat. Yet, partitioning these effects is often difficult, usually requiring an appropriate sampling design and long-term monitoring. Here we quantify, over a 30-yr period, the effects of benthic habitat change and no-take marine reserve (NTMR) protection on the density and species richness of a lightly harvested benthic-feeding reef fish family, the Mullidae (goatfish), at four Philippine islands. Boosted regression trees demonstrated that goatfish density and species richness had strong negative associations with hard coral cover and strong positive associations with cover of dead substratum. No-take marine reserve protection had no effect on the density or species richness of goatfish over 19 and 30 yr at Sumilon and Apo islands, respectively. However, environmental disturbances (e.g., typhoons, coral bleaching) that reduced hard coral cover subsequently led to increases in goatfish numbers for periods ranging from 2 to 8 yr. After initial increases due to benthic disturbance, goatfish populations decreased during coral recovery, occurring on timescales of 10-20 yr. This long-term, "natural experiment" demonstrated that changes to benthic habitat (bottom-up control) had a far greater effect on Philippine goatfish populations than protection from fishing (a top-down effect) in NTMRs. Given the strong positive response of goatfish populations to loss of live hard coral cover, this group of fishes may be a valuable indicator species for habitat degradation on coral reefs.

  10. Eocene benthic foraminiferal assemblages from Central Anatolia (Turkey): Biostratigraphy, stable isotope data, paleoenvironmental and paleontological interpretations

    NASA Astrophysics Data System (ADS)

    Dinçer, Feyza

    2016-02-01

    Stable isotope (δ13C and δ18O) values from Eocene aged shallow marine deposits in two different basins (Haymana and Kırşehir-Kaman) of Central Anatolia and benthic foraminiferal biostratigraphy's corresponding sequences were analyzed to determine paleontological and paleoenvironmental changes. The shallow marine units (Çayraz and Altıpınar formations), deposited as a result of different geological processes in the same period, show differences in paleontological and geochemical properties of the tests. The geological process controlled by environmental factors affect the formation of the chemical structure of foraminiferal calcite. These Lutetian and Bartonian aged formations are represented by five Shallow Benthic Zones. While, the Çayraz section is represented by SBZ 14-18, Boztepe section is represented by SBZ 13-17. With an increase in temperature, the variety of benthic foraminifera decreased, and Assilina exponens became the dominant species in the warm conditions. The most important proxy is δ13C, which reflects the paleoproductivity (food supply) where benthic foraminifera lived. In addition, food supply can be considered to be a more important factor than temperature, as it controls the diversity and abundance of benthic foraminifera.

  11. Differentiating responses to contaminants from responses to other environmental factors for benthic biota in freshwater ecosystems

    SciTech Connect

    Day, K.E.; Reynoldson, T.B.; Rosenberg, D.M.

    1995-12-31

    Many ecological risk assessments (ERAS) of lakes, rivers and streams compare measurements of benthic community structure in specific areas of contamination to similar measurements in reference or ``clean`` areas as a basis for determining impact. However, despite numerous studies documenting alterations of benthic communities as a result of stress, the success of correctly assessing the ``health`` or degradation of these communities depends on how well responses to contamination can be discriminated from responses to other environmental factors. It is important in the ERA process to adequately describe benthic communities and to determine how natural environmental factors (e.g., substrate particle size and texture, organic content, water quality, pH, seston, etc.) may be driving benthic community structure. This knowledge is particularly important when reference areas are distant from stressed areas. This presentation will provide an overview of the environmental factors that are important in structuring natural benthic communities in rivers and lakes and discuss approaches that may be useful in differentiating between natural variability and anthropogenic stress in ERA. Several case studies from the Laurentian Great Lakes and the Fraser River watershed in British Columbia will be discussed.

  12. The MMCO-EOT conundrum: same benthic δ18O, different CO2

    NASA Astrophysics Data System (ADS)

    Stap, Lennert; van de Wal, Roderik; de Boer, Bas; Bintanja, Richard; Lourens, Lucas

    2016-04-01

    Knowledge on temporal variations of Earth's climate over the past 38 Myr largely stems from benthic δ18O records. These records are difficult to interpret, however, since they document combined effects of deep-sea temperature and ice volume variations. Information on CO2 is expanding, but remains highly uncertain and intermittent. Attempts to determine the long-term relations between δ18O, sea level and CO2 from proxy data suffer from paucity of data and apparent inconsistency among different records. One outstanding issue is the difference recorded in proxy CO2 data between the Eocene-Oligocene boundary (EOT) and the Middle-Miocene Climatic Optimum (MMCO), while similar levels of benthic δ18O are shown during these time periods. Here, we take a model-based approach to deconvolute the benthic δ18O signal, and reconcile knowledge on benthic δ18O, sea level, CO2 and temperature. We obtain continuous and mutually consistent 38-Myr-long simulations of these variables, by forcing a coupled ice sheet-climate model inversely with benthic δ18O observations. We investigate the factors influencing Arctic and Antarctic polar amplification, and the relation between sea level and CO2. Furthermore, we show that different CO2 between the EOT and MMCO, as indicated by proxy data, can only be obtained if we impose erosion or tectonic movement of the Antarctic continent over time.

  13. Effects of Stream Fishes on Benthic Primary Productivity: A Mechanistic Test

    NASA Astrophysics Data System (ADS)

    Hargrave, C. W.

    2005-05-01

    I simultaneously tested three alternative hypotheses (the trophic cascade, nutrient enhancement via terrestrial nutrient translocation, and nutrient enhancement via bioturbation) for consumer regulation of primary productivity (PPR) by three widely distributed stream fish species (Orangethroat Darter, Western Mosquitofish, and Bullhead Minnow). I used stream mesocosms fitted with fish and terrestrial input barriers to address relative importance of localized fish predation versus access to terrestrial inputs for fish consumer effects. Orangethroat Darter, a benthic invertivore, increased PPR through an apparent trophic cascade, by localized reduction of benthic grazing invertebrate densities. Western mosquitofish, a surface feeding insectivore, increased PPR by enhancing nutrients through terrestrial nutrient translocation, and had no effect on benthic grazer invertebrate density. Bullhead Minnow, a benthic omnivore that disturbed sediments during foraging, increased PPR through nutrient enhancement via bioturbation, but within specific stream mesocosm areas two which the fish was restricted it also reduced benthic grazing invertebrates. Thus, suggesting this species may have affected PPR through a combination bioturbation and trophic cascade mechanisms. These mechanistic pathways are likely common processes by which fish affect food web structure and ecosystem function in many stream ecosystems.

  14. Application of the benthic index of biotic integrity to environmental monitoring in Chesapeake Bay.

    PubMed

    Llansó, Roberto J; Dauer, Daniel M; Vølstad, Jon H; Scott, Lisa C

    2003-01-01

    The Chesapeake Bay benthic index of biotic integrity (B-IBI) was developed to assess benthic community health and environmental quality in Chesapeake Bay. The B-IBI provides Chesapeake Bay monitoring programs with a uniform tool with which to characterize bay-wide benthic community condition and assess the health of the Bay. A probability-based design permits unbiased annual estimates of areal degradation within the Chesapeake Bay and its tributaries with quantifiable precision. However, of greatest interest to managers is the identification of problem areas most in need of restoration. Here we apply the B-IBI to benthic data collected in the Bay since 1994 to assess benthic community degradation by Chesapeake Bay Program segment and water depth. We used a new B-IBI classification system that improves the reliability of the estimates of degradation. Estimates were produced for 67 Chesapeake Bay Program segments. Greatest degradation was found in areas that are known to experience hypoxia or show toxic contamination, such as the mesohaline portion of the Potomac River, the Patapsco River, and the Maryland mainstem. Logistic regression models revealed increased probability of degraded benthos with depth for the lower Potomac River, Patapsco River. Nanticoke River, lower York River, and the Maryland mainstem. Our assessment of degradation by segment and water depth provided greater resolution of relative condition than previously available, and helped define the extent of degradation in Chesapeake Bay.

  15. Seasonal dynamics of benthic macroinvertebrates of Pond B, Savannah River Plant Aiken, South Carolina

    SciTech Connect

    Whicker, A.D.

    1988-01-01

    This study was designed to evaluate the spatial and seasonal distributions, compositions, and abundances of benthic macroinvertebrates in Pond B after 20 years of postthermal recovery. There are both basic and applied uses for the data gathered during the study. The examination of species composition and abundances as a function of season and water depth adds to the base of general knowledge on the benthic invertebrates of lentic systems. The current species composition also provides an indication of a portion of the postthermal community succession. An estimate of the biomass of the benthic community permits a calculation of the radionuclide inventory in this ecosystem compartment, if average concentrations are concurrently determined. Such data may then be used to predict food chain transfers to higher consumers and potential export from the ecosystem. Specific hypotheses tested were: (1) densities of certain benthic invertebrate communities vary with season, (2) densities of benthic invertebrates vary with water depth, and (3) the effect of season on invertebrate density depends on water depth (i.e. there is an interaction between depth and season). Other community parameters considered were species composition, diversity, and relative biomass by taxa. 30 refs., 5 figs., 9 tabs.

  16. Taxonomic diversity and structure of benthic macroinvertebrates in Aby Lagoon (Ivory Coast, West Africa).

    PubMed

    Kouadio, K N; Diomandé, D; Ouattara, A; Koné, Y J M; Gourène, G

    2008-09-15

    The benthic macroinvertebrates of Aby lagoon (West Africa: Ivory coast) was studied during four seasons (high dry season, high rainy season, low dry season and low rainy season, respectively) from June 2006 to March 2007. The distribution of the benthic macroinvertebrates species was recorded at 13 stations on the whole of the lagoon. A total of 62 taxa of benthic macroinvertebrates belonging to 28 families and 10 orders were listed. The molluscs and crustaceans dominate qualitatively by adding up 51 and 24%, respectively of the total number of organisms. Five taxa (Corbula trigona (20%), Pachymelania aurita (12%), Clibernhardius cooki (7%), Oligochaeta (7%) and Crassostrea gasar (6%) accounted for 52% of total abundance. Classification analysis used to perform the characterisation of the lagoon on the basis of benthic macroinvertebrates showed the existence of four main clusters in which the seasonal pattern in benthic macroinvertebrates were very similar in the four seasons. In contrast the species richness and diversity indices were significantly different. Furthermore these indices where higher in the stations closer to the sea and surrounded by mangrove trees (southern area) compared to the inland ones.

  17. Benthic macroinvertebrates diversity and water quality assessment at Sungai Congkak recreational area, Hulu Langat, Selangor

    NASA Astrophysics Data System (ADS)

    Mustaqim-Alias, M.; Ahmad, A. K.

    2013-11-01

    A study on benthic macroinvertebrates diversity and water quality assessment was conducted at Sungai Congkak recreational area in Hulu Langat, Selangor. Sums of eight sampling stations were selected with a distance of 100-200 m interval between each station. Benthic macroinvertebrates was sampled using a Surber net, while water sampling and analysis were undertaken according to HACH standard methods. A total of 3754 individuals from 40 families of benthic macroinvertebrates were recorded at this river. Ecological indices namely Shannon diversity index (2.49), Pielou evenness index (0.77) and Margalef richness index (4.06) demonstrate that Sungai Congkak is at good condition and benthic macroinvertebrates has homogeneous distribution along the sampling sites. Elmidae, Hydrophilidae, Baetidae and Perlidae were most dominant families present in that area and adapted progressively with excellent water quality (> 300 individuals). As regards to Malaysian's Water Quality Index (WQI), the study area at Sungai Congkak is classified in class I which has good water quality conditions. The Pearson correlation test indicates that ecological indices have strong correlation toward WQI at all sampling stations. As a conclusion, the benthic macroinvertebrates and WQI data demonstrated that Sungai Congkak is clean and suitable as recreational stream based on this study.

  18. Extremely heat tolerant photosymbiosis in a shallow marine benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Schmidt, Christiane; Danna, Titelboim; Janett, Brandt; Raphael, Morard; Barak, Herut; Sigal, Abramovich; Ahuva, Almogi-Labin; Michal, Kucera

    2016-04-01

    Thermal stress leads to the loss of algal symbionts (bleaching) in many shallow marine calcifiers including foraminifera. The bleaching threshold often occurs at water temperatures, which are likely to be exceeded in the near future due to global warming. Preadaptation represents one mechanism allowing photosymbiotic organisms to persist under warmer conditions, providing the tolerance can be carried to new habitats. Here we provide evidence for the existence of such adaptation in the benthic foraminifera Pararotalia calcariformata recently discovered in the eastern Mediterranean. We identify its symbionts as a consortium of diatom species dominated by Minutocellus polymorphus. We show that in the field, the foraminifera retains its pigments at a thermally polluted site, where peak water temperatures reach 36°C. To test whether this tolerance represents a widespread adaptation, we conducted manipulative experiments exposing populations from an unpolluted site to elevated temperatures for up to three weeks. The populations were kept in co-culture with the more thermally sensitive diatom-bearing foraminifera Amphistegina lobifera. Reduced photosynthetic activity in A. lobifera occurred at 32°C whereas photochemical stress in P. calcariformata was first observed during exposure to 36°C and chronic photoinhibition (but not mortality) first occurred at 42°C. Survivorship was high in all treatments, and growth was observed under thermal conditions similar to summer maxima at the thermally polluted site (35-36°C). The photosymbiosis in P. calcariformata is unusually thermally tolerant for a photosymbiont-bearing eukaryote. The thermal tolerance of this photosymbiosis is present in a natural environment where its thermal threshold is never realized. These observations imply that photosymbiosis in marine protists can respond to elevated temperatures by drawing on a pool of naturally occurring pre-adaptations. It also provides a perspective on the massive occurrence of

  19. Biological vs. physical mixing effects on benthic food web dynamics.

    PubMed

    Braeckman, Ulrike; Provoost, Pieter; Moens, Tom; Soetaert, Karline; Middelburg, Jack J; Vincx, Magda; Vanaverbeke, Jan

    2011-01-01

    Biological particle mixing (bioturbation) and solute transfer (bio-irrigation) contribute extensively to ecosystem functioning in sediments where physical mixing is low. Macrobenthos transports oxygen and organic matter deeper into the sediment, thereby likely providing favourable niches to lower trophic levels (i.e., smaller benthic animals such as meiofauna and bacteria) and thus stimulating mineralisation. Whether this biological transport facilitates fresh organic matter assimilation by the metazoan lower part of the food web through niche establishment (i.e., ecosystem engineering) or rather deprives them from food sources, is so far unclear. We investigated the effects of the ecosystem engineers Lanice conchilega (bio-irrigator) and Abra alba (bioturbator) compared to abiotic physical mixing events on survival and food uptake of nematodes after a simulated phytoplankton bloom. The (13)C labelled diatom Skeletonema costatum was added to 4 treatments: (1) microcosms containing the bioturbator, (2) microcosms containing the bio-irrigator, (3) control microcosms and (4) microcosms with abiotic manual surface mixing. Nematode survival and subsurface peaks in nematode density profiles were most pronounced in the bio-irrigator treatment. However, nematode specific uptake (Δδ(13)C) of the added diatoms was highest in the physical mixing treatment, where macrobenthos was absent and the diatom (13)C was homogenised. Overall, nematodes fed preferentially on bulk sedimentary organic material rather than the added diatoms. The total C budget (µg C m(-2)), which included TO(13)C remaining in the sediment, respiration, nematode and macrobenthic uptake, highlighted the limited assimilation by the metazoan benthos and the major role of bacterial respiration. In summary, bioturbation and especially bio-irrigation facilitated the lower trophic levels mainly over the long-term through niche establishment. Since the freshly added diatoms represented only a limited food source

  20. Maximum ecological potential of tropical reservoirs and benthic invertebrate communities.

    PubMed

    Molozzi, Joseline; Feio, Maria João; Salas, Fuensanta; Marques, João Carlos; Callisto, Marcos

    2013-08-01

    The Reference Condition Approach (RCA) is now widely adopted as a basis for the evaluation of the ecological quality of water bodies. In accordance with the RCA, the integrity of communities found in a given location should be analyzed according to their deviation from the communities that would be expected in the absence of anthropogenic disturbances. The RCA was used here with the aim of defining the Maximum Ecological Potential (MEP) of tropical reservoirs located in the hydrographical basin of the Paraopeba River in the state of Minas Gerais, Brazil. Among the reservoirs, Serra Azul is used as a water supply and is located in a core area of environmental protection where tourism is not allowed and the native vegetation is conserved. The benthic macroinvertebrate communities at 90 sites located in three reservoirs were analyzed and sampled every 3 months over 2 years. The temporal patterns of the communities in the three reservoirs were analyzed (2nd-STAGE MDS and ANOSIM) and were not significantly related to seasonal fluctuations in temperature and precipitation. Twenty-eight sites belonging to the Serra Azul reservoir were selected to define the MEP of these reservoirs because these sites had the lowest human disturbance levels. The macroinvertebrate taxa present in the selected MEP sites are similar to those of natural lakes and different from the communities of disturbed sites. The biological classification of these sites revealed two groups with distinct macroinvertebrate communities. This distinction was related to climatic variables, bottom substrate type, the presence of gravel/boulders, coarse sand, silt, clay or muck, depth, and the shoreline substrate zone. These two subsets of biological communities and respective environmental conditions can serve as a basis for the future implementation of ecological quality monitoring programs for tropical reservoirs in the study area. This approach can also, however, be implemented in other geographic areas

  1. Biological vs. physical mixing effects on benthic food web dynamics.

    PubMed

    Braeckman, Ulrike; Provoost, Pieter; Moens, Tom; Soetaert, Karline; Middelburg, Jack J; Vincx, Magda; Vanaverbeke, Jan

    2011-01-01

    Biological particle mixing (bioturbation) and solute transfer (bio-irrigation) contribute extensively to ecosystem functioning in sediments where physical mixing is low. Macrobenthos transports oxygen and organic matter deeper into the sediment, thereby likely providing favourable niches to lower trophic levels (i.e., smaller benthic animals such as meiofauna and bacteria) and thus stimulating mineralisation. Whether this biological transport facilitates fresh organic matter assimilation by the metazoan lower part of the food web through niche establishment (i.e., ecosystem engineering) or rather deprives them from food sources, is so far unclear. We investigated the effects of the ecosystem engineers Lanice conchilega (bio-irrigator) and Abra alba (bioturbator) compared to abiotic physical mixing events on survival and food uptake of nematodes after a simulated phytoplankton bloom. The (13)C labelled diatom Skeletonema costatum was added to 4 treatments: (1) microcosms containing the bioturbator, (2) microcosms containing the bio-irrigator, (3) control microcosms and (4) microcosms with abiotic manual surface mixing. Nematode survival and subsurface peaks in nematode density profiles were most pronounced in the bio-irrigator treatment. However, nematode specific uptake (Δδ(13)C) of the added diatoms was highest in the physical mixing treatment, where macrobenthos was absent and the diatom (13)C was homogenised. Overall, nematodes fed preferentially on bulk sedimentary organic material rather than the added diatoms. The total C budget (µg C m(-2)), which included TO(13)C remaining in the sediment, respiration, nematode and macrobenthic uptake, highlighted the limited assimilation by the metazoan benthos and the major role of bacterial respiration. In summary, bioturbation and especially bio-irrigation facilitated the lower trophic levels mainly over the long-term through niche establishment. Since the freshly added diatoms represented only a limited food source

  2. Marine benthic ecological functioning over decreasing taxonomic richness

    NASA Astrophysics Data System (ADS)

    Törnroos, Anna; Bonsdorff, Erik; Bremner, Julie; Blomqvist, Mats; Josefson, Alf B.; Garcia, Clement; Warzocha, Jan

    2015-04-01

    Alterations to ecosystem function due to reductions in species richness are predicted to increase as humans continue to affect the marine environment, especially in coastal areas, which serve as the interface between land and sea. The potential functional consequences due to reductions in species diversity have attracted considerable attention recently but little is known about the consequence of such loss in natural communities. We examined how the potential for function is affected by natural reductions in taxon richness using empirical (non-simulated) coastal marine benthic macrofaunal data from the Skagerrak-Baltic Sea region (N. Europe), where taxon richness decreases 25-fold, from 151 to 6 taxa. To estimate functional changes we defined multiple traits (10 traits and 51 categories) on which trait category richness, functional diversity (FD) and number of taxa per trait category were calculated. Our results show that decrease in taxon richness leads to an overall reduction in function but functional richness remains comparatively high even at the lowest level of taxon richness. Although the taxonomic reduction was sharp, up to 96% of total taxon richness, we identified both potential thresholds in functioning and subtler changes where function was maintained along the gradient. The functional changes were not only caused by reductions in taxa per trait category, some categories were maintained or even increased. Primarily, the reduction in species richness altered trait categories related to feeding, living and movement and thus potentially could have an effect on various ecosystem processes. This highlights the importance of recognising ecosystem multifunctionality, especially at low taxonomic richness. We also found that in this system rare species (singletons) did not stand for the functional complexities and changes. Our findings were consistent with theoretical and experimental predictions and suggest that a large proportion of the information about

  3. Biological vs. Physical Mixing Effects on Benthic Food Web Dynamics

    PubMed Central

    Braeckman, Ulrike; Provoost, Pieter; Moens, Tom; Soetaert, Karline; Middelburg, Jack J.; Vincx, Magda; Vanaverbeke, Jan

    2011-01-01

    Biological particle mixing (bioturbation) and solute transfer (bio-irrigation) contribute extensively to ecosystem functioning in sediments where physical mixing is low. Macrobenthos transports oxygen and organic matter deeper into the sediment, thereby likely providing favourable niches to lower trophic levels (i.e., smaller benthic animals such as meiofauna and bacteria) and thus stimulating mineralisation. Whether this biological transport facilitates fresh organic matter assimilation by the metazoan lower part of the food web through niche establishment (i.e., ecosystem engineering) or rather deprives them from food sources, is so far unclear. We investigated the effects of the ecosystem engineers Lanice conchilega (bio-irrigator) and Abra alba (bioturbator) compared to abiotic physical mixing events on survival and food uptake of nematodes after a simulated phytoplankton bloom. The 13C labelled diatom Skeletonema costatum was added to 4 treatments: (1) microcosms containing the bioturbator, (2) microcosms containing the bio-irrigator, (3) control microcosms and (4) microcosms with abiotic manual surface mixing. Nematode survival and subsurface peaks in nematode density profiles were most pronounced in the bio-irrigator treatment. However, nematode specific uptake (Δδ13C) of the added diatoms was highest in the physical mixing treatment, where macrobenthos was absent and the diatom 13C was homogenised. Overall, nematodes fed preferentially on bulk sedimentary organic material rather than the added diatoms. The total C budget (µg C m−2), which included TO13C remaining in the sediment, respiration, nematode and macrobenthic uptake, highlighted the limited assimilation by the metazoan benthos and the major role of bacterial respiration. In summary, bioturbation and especially bio-irrigation facilitated the lower trophic levels mainly over the long-term through niche establishment. Since the freshly added diatoms represented only a limited food source for

  4. A workflow for reproducing mean benthic gas fluxes

    NASA Astrophysics Data System (ADS)

    Fulweiler, Robinson W.; Emery, Hollie E.; Maguire, Timothy J.

    2016-08-01

    Long-term data sets provide unique opportunities to examine temporal variability of key ecosystem processes. The need for such data sets is becoming increasingly important as we try to quantify the impact of human activities across various scales and in some cases, as we try to determine the success of management interventions. Unfortunately, long-term benthic flux data sets for coastal ecosystems are rare and curating them is a challenge. If we wish to make our data available to others now and into the future, however, then we need to provide mechanisms that allow others to understand our methods, access the data, reproduce the results, and see updates as they become available. Here we use techniques, learned through the EarthCube Ontosoft Geoscience Paper of the Future project, to develop best practices to allow us to share a long-term data set of directly measured net sediment N2 fluxes and sediment oxygen demand at two sites in Narragansett Bay, Rhode Island (USA). This technical report describes the process we used, the challenges we faced, and the steps we will take in the future to ensure transparency and reproducibility. By developing these data and software sharing tools we hope to help disseminate well-curated data with provenance as well as products from these data, so that the community can better assess how this temperate estuary has changed over time. We also hope to provide a data sharing model for others to follow so that long-term estuarine data are more easily shared and not lost over time.

  5. Pelagic-benthic coupling and diagenesis of nucleic acids in a deep-sea continental margin and an open-slope system of the Eastern Mediterranean.

    PubMed

    Dell'anno, Antonio; Corinaldesi, Cinzia; Stavrakakis, Spyros; Lykousis, Vasilis; Danovaro, Roberto

    2005-10-01

    Downward fluxes of nucleic acids adsorbed onto settling particles play a key role in the supply of organic phosphorus and genetic material to the ocean interior. However, information on pelagic-benthic coupling, diagenesis, and processes controlling nucleic acid preservation in deep-sea sediments is practically nonexistent. In this study, we compared nucleic acid fluxes, sedimentary DNA and RNA concentrations, and the enzymatically hydrolyzable fraction of DNA in a bathyal continental margin (North Aegean Sea) and an open-sea system (South Aegean Sea) of the Eastern Mediterranean. The two systems displayed contrasting patterns of nucleic acid fluxes, which increased significantly with depth in the North Aegean Sea and decreased with depth in the South Aegean Sea. These results suggest that in continental margin and open-ocean systems different processes control the nucleic acid supply to the sea floor. Differences in nucleic acid fluxes were reflected by nucleic acid concentrations in the sediments, which reached extremely high values in the North Aegean Sea. In this system, a large fraction of DNA may be buried, as suggested by the large fraction of DNA resistant to nuclease degradation and by estimates of burial efficiency (ca. eight times higher in the North than in the South Aegean Sea). Overall, the results reported here suggest that the preservation of DNA in deeper sediment layers may be favored in benthic systems characterized by high sedimentation rates.

  6. Size-fractionated major particle composition and concentrations from the US GEOTRACES North Atlantic Zonal Transect

    NASA Astrophysics Data System (ADS)

    Lam, Phoebe J.; Ohnemus, Daniel C.; Auro, Maureen E.

    2015-06-01

    The concentration and the major phase composition (particulate organic matter, CaCO3, opal, lithogenic matter, and iron and manganese oxyhydroxides) of marine particles is thought to determine the scavenging removal of particle-reactive TEIs. Particles are also the vector for transferring carbon from the atmosphere to the deep ocean via the biological carbon pump, and their composition may determine the efficiency and strength of this transfer. Here, we present the first full ocean depth section of size-fractionated (1-51 μm, >51 μm) suspended particulate matter (SPM) concentration and major phase composition from the US GEOTRACES North Atlantic Zonal Transect between Woods Hole, MA and Lisbon, Portugal conducted in 2010 and 2011. Several major particle features are notable in the section: intense benthic nepheloid layers were observed in the western North American margin with concentrations of SPM of up to 1648 μg/L, two to three orders of magnitude higher than surrounding waters, that were dominated by lithogenic material. A more moderate benthic nepheloid layer was also observed in the eastern Mauritanian margin (44 μg/L) that had a lower lithogenic content and, notably, significant concentrations of iron and manganese oxyhydroxides (2.5% each). An intermediate nepheloid layer reaching 102 μg/L, an order of magnitude above surrounding waters, was observed associated with the Mediterranean Outflow. Finally, there was a factor of two enhancement in SPM at the TAG hydrothermal plume due almost entirely to the addition of iron oxyhydroxides from the hydrothermal vent. We observe correlations between POC and CaCO3 in large (>51 μm) particles in the upper 2000 m, but not deeper than 2000 m, and no correlations between POC and CaCO3 at any depth in small (<51 μm) particles. There were also no correlations between POC and lithogenic material in large particles. Overall, there were very large uncertainties associated with all regression coefficients for mineral

  7. Benthic foraminiferal response to trace element pollution-the case study of the Gulf of Milazzo, NE Sicily (Central Mediterranean Sea).

    PubMed

    Cosentino, Claudia; Pepe, Fabrizio; Scopelliti, Giovanna; Calabrò, Monica; Caruso, Antonio

    2013-10-01

    The response of benthic foraminiferal assemblages to trace element pollution in the marine sediments of the Gulf of Milazzo (north-eastern Sicily) was investigated. Since the 1960s, this coastal area has been a preferred site for the development of two small marinas and a commercial harbour as well as for heavy industry. Forty samples collected in the uppermost 3-4 cm of an undisturbed layer of sediment in the littoral environment were used for this benthic foraminiferal analysis. The enrichment factors (EFs) of selected trace elements (As, Co, Cr, Cu, Mn, Ni, Pb and Zn) were also calculated. Changes both in benthic foraminiferal assemblages and in some trace elements concentrations have provided evidence that the gulf's littoral zone can be subdivided into three sectors characterised by environmental changes in the marine ecosystem. In the sector unpolluted, close to the Milazzo Cape, foraminiferal assemblages exhibit high values of species richness and foraminiferal density while trace element concentrations and their EFs are very low. Here, the highest densities of Miliolids and epiphytic species are present. On the contrary, in the sector polluted, from the marinas to the crude oil refinery, foraminiferal density and species diversity are low, and assemblages are dominated, albeit with very low densities, by species that tolerate stressed environmental conditions, such as LOFAs, agglutinants and Ammonia spp. Here, the highest trace elements concentrations of Pb, Zn and Cu and related EFs were detected. Eastwards, in the sector moderately polluted, foraminiferal populations are quite poor. They are characterised by low values of species richness and foraminiferal densities, nevertheless trace element concentrations become lower than in the other sectors and their EFs are often below 1. Deformed foraminifera, with percentages up to 7.14 %, were found in all three of the sectors. Differences in benthic foraminiferal assemblages, coupled with results from

  8. Benthic foraminiferal response to trace element pollution-the case study of the Gulf of Milazzo, NE Sicily (Central Mediterranean Sea).

    PubMed

    Cosentino, Claudia; Pepe, Fabrizio; Scopelliti, Giovanna; Calabrò, Monica; Caruso, Antonio

    2013-10-01

    The response of benthic foraminiferal assemblages to trace element pollution in the marine sediments of the Gulf of Milazzo (north-eastern Sicily) was investigated. Since the 1960s, this coastal area has been a preferred site for the development of two small marinas and a commercial harbour as well as for heavy industry. Forty samples collected in the uppermost 3-4 cm of an undisturbed layer of sediment in the littoral environment were used for this benthic foraminiferal analysis. The enrichment factors (EFs) of selected trace elements (As, Co, Cr, Cu, Mn, Ni, Pb and Zn) were also calculated. Changes both in benthic foraminiferal assemblages and in some trace elements concentrations have provided evidence that the gulf's littoral zone can be subdivided into three sectors characterised by environmental changes in the marine ecosystem. In the sector unpolluted, close to the Milazzo Cape, foraminiferal assemblages exhibit high values of species richness and foraminiferal density while trace element concentrations and their EFs are very low. Here, the highest densities of Miliolids and epiphytic species are present. On the contrary, in the sector polluted, from the marinas to the crude oil refinery, foraminiferal density and species diversity are low, and assemblages are dominated, albeit with very low densities, by species that tolerate stressed environmental conditions, such as LOFAs, agglutinants and Ammonia spp. Here, the highest trace elements concentrations of Pb, Zn and Cu and related EFs were detected. Eastwards, in the sector moderately polluted, foraminiferal populations are quite poor. They are characterised by low values of species richness and foraminiferal densities, nevertheless trace element concentrations become lower than in the other sectors and their EFs are often below 1. Deformed foraminifera, with percentages up to 7.14 %, were found in all three of the sectors. Differences in benthic foraminiferal assemblages, coupled with results from

  9. Complex spatial and temporal variation of subtropical benthic macrofauna under sewage impact.

    PubMed

    Souza, F M; Brauko, K M; Gilbert, E R; Martins, C C; Lana, P C; Camargo, M G

    2016-05-01

    To better understand variation in sewage-impacted benthic macrofauna from subtropical tidal flats over time and space, we applied a five-factor linear model at a hierarchy of spatial (Condition - Contaminated or Non-Contaminated, Tidal Flat and Plot) and temporal scales (Season and Fortnight). The Contaminated site showed high levels of coprostanol and the presence of Paranais cf frici as markers or indicators of organic enrichment. Differences between Seasons were more pronounced for the faunal variation patterns than for the other parameters, with lower species richness and abundance in summer. There were significant interactions between Fortnight and Tidal Flat for most variables, reflecting marked heterogeneity within Tidal Flats. Benthic community has significantly changed over short periods of time. These rapid changes may lead to erroneous interpretations and mask the true sources of variation. Our results clearly demonstrate the need to better understand benthic temporal variability even at small scales. PMID:26994465

  10. Evaluation of bioremediation potential of three benthic annelids in organically polluted marine sediment.

    PubMed

    Ito, Mana; Ito, Katsutoshi; Ohta, Kohei; Hano, Takeshi; Onduka, Toshimitsu; Mochida, Kazuhiko; Fujii, Kazunori

    2016-11-01

    This study aimed to evaluate the possible remedial effects of three marine benthic annelids on organically polluted sediments from the waters of Hatsukaichi Marina, Hiroshima, Japan. Two polychaetes, Perinereis nuntia and Capitella cf. teleta, and an oligochaete, Thalassodrilides sp., were incubated in sediments for 50 days. Their effects on physicochemical properties such as organic matter (loss on ignition), redox potential (Eh), acid volatile sulfides (AVS), and degradation of polycyclic aromatic hydrocarbons (PAHs) were assessed. The polychaetes P. nuntia and C. cf. teleta significantly increased Eh level and decreased AVS level compared with the oligochaete Thalassodrilides sp. and control (without benthic organisms). Total PAH concentration significantly decreased from the initial level with all three groups; Thalassodrilides sp. had a marked ability to reduce PAHs in sediment. These results indicate that benthic organisms have species-specific remediation properties and ecological functions in organically polluted sediments. PMID:27565306

  11. Empirical approaches to more accurately predict benthic-pelagic coupling in biogeochemical ocean models

    NASA Astrophysics Data System (ADS)

    Dale, Andy; Stolpovsky, Konstantin; Wallmann, Klaus

    2016-04-01

    The recycling and burial of biogenic material in the sea floor plays a key role in the regulation of ocean chemistry. Proper consideration of these processes in ocean biogeochemical models is becoming increasingly recognized as an important step in model validation and prediction. However, the rate of organic matter remineralization in sediments and the benthic flux of redox-sensitive elements are difficult to predict a priori. In this communication, examples of empirical benthic flux models that can be coupled to earth system models to predict sediment-water exchange in the open ocean are presented. Large uncertainties hindering further progress in this field include knowledge of the reactivity of organic carbon reaching the sediment, the importance of episodic variability in bottom water chemistry and particle rain rates (for both the deep-sea and margins) and the role of benthic fauna. How do we meet the challenge?

  12. Effects of Hurricane Katrina on benthic macroinvertebrate communities along the northern Gulf of Mexico coast.

    PubMed

    Engle, Virginia D; Hyland, Jeffrey L; Cooksey, Cynthia

    2009-03-01

    The effects of Hurricane Katrina on benthic fauna and habitat quality in coastal waters of Louisiana, Mississippi, and Alabama, USA, were assessed in October, 2005, 2 months after the hurricane made landfall between New Orleans, LA and Biloxi, MS. Benthic macrofaunal samples, sediment chemical concentrations, and water quality measurements from 60 sites in Lake Pontchartrain and Mississippi Sound were compared with pre-hurricane conditions from 2000-2004. Post-hurricane benthic communities had significant reductions in numbers of taxa, H(') diversity, and abundance as well as shifts in composition and ranking of dominant taxa. These effects were not associated with changes in chemical contamination, organic enrichment of sediments, or hypoxia and were likely due to hurricane-related scouring and changes in salinity.

  13. Effects of hypoxia on biofilms and subsequently larval settlement of benthic invertebrates.

    PubMed

    Cheung, S G; Chan, C Y S; Po, B H K; Li, A L; Leung, J Y S; Qiu, J W; Ang, P O; Thiyagarajan, V; Shin, P K S; Chiu, J M Y

    2014-08-30

    Biofilms on submerged surfaces are important in determining larval settlement of most marine benthic invertebrates. We investigated if exposure of biofilms to hypoxia would alter the larval settlement pattern and result in a shift in benthic invertebrate community structure in the field. Biofilms were first exposed to hypoxia or normoxia in laboratory microcosms for 7 days, and then deployed in the field for another 7 days to allow for larval settlement and recruitment to occur. Using terminal-restriction fragment length polymorphism of the 16S rRNA gene, this study showed that hypoxia altered the biofilm bacterial community composition, and the difference between the hypoxic and normoxic treatments increased with the time of exposure period. This study also demonstrated significantly different benthic invertebrate community structures as a result of biofilm exposure to hypoxia and that the hypoxic and normoxic treatments were dominated by Hydroides sp. and Folliculina sp., respectively.

  14. Detection and identification of benthic communities and shoreline features in Biscayne Bay

    NASA Technical Reports Server (NTRS)

    Kolipinski, M. C.; Higer, A. L.

    1970-01-01

    Progress made in the development of a technique for identifying and delinating benthic and shoreline communities using multispectral imagery is described. Images were collected with a multispectral scanner system mounted in a C-47 aircraft. Concurrent with the overflight, ecological ground- and sea-truth information was collected at 19 sites in the bay and on the shore. Preliminary processing of the scanner imagery with a CDC 1604 digital computer provided the optimum channels for discernment among different underwater and coastal objects. Automatic mapping of the benthic plants by multiband imagery and the mapping of isotherms and hydrodynamic parameters by digital model can become an effective predictive ecological tool when coupled together. Using the two systems, it appears possible to predict conditions that could adversely affect the benthic communities. With the advent of the ERTS satellites and space platforms, imagery data could be obtained which, when used in conjunction with water-level and meteorological data, would provide for continuous ecological monitoring.

  15. Evaluation of bioremediation potential of three benthic annelids in organically polluted marine sediment.

    PubMed

    Ito, Mana; Ito, Katsutoshi; Ohta, Kohei; Hano, Takeshi; Onduka, Toshimitsu; Mochida, Kazuhiko; Fujii, Kazunori

    2016-11-01

    This study aimed to evaluate the possible remedial effects of three marine benthic annelids on organically polluted sediments from the waters of Hatsukaichi Marina, Hiroshima, Japan. Two polychaetes, Perinereis nuntia and Capitella cf. teleta, and an oligochaete, Thalassodrilides sp., were incubated in sediments for 50 days. Their effects on physicochemical properties such as organic matter (loss on ignition), redox potential (Eh), acid volatile sulfides (AVS), and degradation of polycyclic aromatic hydrocarbons (PAHs) were assessed. The polychaetes P. nuntia and C. cf. teleta significantly increased Eh level and decreased AVS level compared with the oligochaete Thalassodrilides sp. and control (without benthic organisms). Total PAH concentration significantly decreased from the initial level with all three groups; Thalassodrilides sp. had a marked ability to reduce PAHs in sediment. These results indicate that benthic organisms have species-specific remediation properties and ecological functions in organically polluted sediments.

  16. Persistent organic pollutants in benthic and pelagic organisms off Adélie Land, Antarctica.

    PubMed

    Goutte, A; Chevreuil, M; Alliot, F; Chastel, O; Cherel, Y; Eléaume, M; Massé, G

    2013-12-15

    The concentrations of polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), pentachlorobenzene (PeCB) and polybrominated diphenylethers (PBDE) were described in benthic and pelagic species collected off Adélie Land, Antarctica. Strong differences were observed among species, with reduced PeCB and HCB levels in benthic species, and elevated PCB levels in the Antarctic yellowbelly rockcod, the Antarctic sea urchin and the snow petrel. Lower-chlorinated congeners were predominant in krill; penta-PCBs in benthic organisms; hexa- and hepta-PCBs in seabirds and cryopelagic fish. This segregation may result from sedimentation process, specific accumulation and excretion, and/or biotransformation processes. The presence of PBDEs in Antarctic coastal organisms may originate from atmospheric transport and partly from a contamination by local sources. Although POP levels in Antarctic marine organisms were substantially lower than in Arctic and temperate organisms, very little is known about their toxic effects on these cold-adapted species, with high degree of endemism. PMID:24237994

  17. Evaluation of potential relationships between benthic community structure and toxic metals in Laizhou Bay.

    PubMed

    Wu, Bin; Song, Jinming; Li, Xuegang

    2014-10-15

    The objective of the present study was to examine the relationships between benthic community structure and toxic metals using bivariate/multivariate techniques at 17 sediment locations in Laizhou Bay, North China. Sediment chemical data were evaluated against geochemical background values and sediment quality guidelines, which identified Cu and As as contaminants of concern with a moderate potential for adverse effects. Benthic community data were subjected to non-metric multidimensional scaling, which generated four groups of stations. Spearman rank correlation was then employed to explore the relationships between the major axes of heavy metals and benthic community structure. However, weak and insignificant correlations were found between these axes, indicating that contaminants of concern may not be the primary explanatory factors. Polychaeta were abundant in southern Laizhou Bay, serving as a warning regarding the health status of the ecosystem. Integrated sediment quality assessment showed sediments from northern central locations were impaired, displaying less diverse benthos and higher metal contamination.

  18. Sediment characteristics and benthic ecological status in contrasting marine environments of subtropical Hong Kong.

    PubMed

    Chan, Alice K Y; Xu, Wen-Zhe; Liu, Xiao-Shou; Cheung, Siu Gin; Shin, Paul K S

    2016-02-15

    Sediment characteristics and benthic communities on a finer sampling scale in four contrasting environments in subtropical Hong Kong were analyzed in summer and winter 2012. In two harbour habitats which suffered from historic sewage pollution or hypoxic events, organic carbon, nutrient and trace metal content in the sediment were significantly higher than that in an offshore area and a marine reserve. The relatively low organic and nutrient content in the offshore habitat could be resulted from enhanced resuspension of such materials from the seabed owing to intense water mixing and disturbance caused by bottom trawling. The biotic indices AMBI and M-AMBI were shown to be useful in assessing the benthic ecological status of these habitats. Such indices can also be more sensitive than sediment physico-chemical parameters in differentiating the response of macrofauna to seasonal changes in the benthic environment.

  19. Modelling impacts and recovery in benthic communities exposed to localised high CO2.

    PubMed

    Lessin, Gennadi; Artioli, Yuri; Queirós, Ana M; Widdicombe, Stephen; Blackford, Jerry C

    2016-08-15

    Regulations pertaining to carbon dioxide capture with offshore storage (CCS) require an understanding of the potential localised environmental impacts and demonstrably suitable monitoring practices. This study uses a marine ecosystem model to examine a comprehensive range of hypothetical CO2 leakage scenarios, quantifying both impact and recovery time within the benthic system. Whilst significant mortalities and long recovery times were projected for the larger and longer term scenarios, shorter-term or low level exposures lead to reduced projected impacts. This suggests that efficient monitoring and leak mitigation strategies, coupled with appropriate selection of storage sites can effectively limit concerns regarding localised environmental impacts from CCS. The feedbacks and interactions between physiological and ecological responses simulated reveal that benthic responses to CO2 leakage could be complex. This type of modelling investigation can aid the understanding of impact potential, the role of benthic community recovery and inform the design of baseline and monitoring surveys.

  20. Modelling impacts and recovery in benthic communities exposed to localised high CO2.

    PubMed

    Lessin, Gennadi; Artioli, Yuri; Queirós, Ana M; Widdicombe, Stephen; Blackford, Jerry C

    2016-08-15

    Regulations pertaining to carbon dioxide capture with offshore storage (CCS) require an understanding of the potential localised environmental impacts and demonstrably suitable monitoring practices. This study uses a marine ecosystem model to examine a comprehensive range of hypothetical CO2 leakage scenarios, quantifying both impact and recovery time within the benthic system. Whilst significant mortalities and long recovery times were projected for the larger and longer term scenarios, shorter-term or low level exposures lead to reduced projected impacts. This suggests that efficient monitoring and leak mitigation strategies, coupled with appropriate selection of storage sites can effectively limit concerns regarding localised environmental impacts from CCS. The feedbacks and interactions between physiological and ecological responses simulated reveal that benthic responses to CO2 leakage could be complex. This type of modelling investigation can aid the understanding of impact potential, the role of benthic community recovery and inform the design of baseline and monitoring surveys. PMID:27289279

  1. Methods for collecting benthic invertebrate samples as part of the National Water-Quality Assessment Program

    USGS Publications Warehouse

    Cuffney, Thomas F.; Gurtz, Martin E.; Meador, Michael R.

    1993-01-01

    Benthic invertebrate communities are evaluated as part of the ecological survey component of the U.S. Geological Survey's National Water-Quality Assessment Program. These biological data are collected along with physical and chemical data to assess water-quality conditions and to develop an understanding of the factors that affect water-quality conditions locally, regionally, and nationally. The objectives of benthic invertebrate community characterizations are to (1) develop for each site a list of tax a within the associated stream reach and (2) determine the structure of benthic invertebrate communities within selected habitats of that reach. A nationally consistent approach is used to achieve these objectives. This approach provides guidance on site, reach, and habitat selection and methods and equipment for qualitative multihabitat sampling and semi-quantitative single habitat sampling. Appropriate quality-assurance and quality-control guidelines are used to maximize the ability to analyze data within and among study units.

  2. Swept Away: Resuspension of Bacterial Mats Regulates Benthic-Pelagic Exchange of Sulfur

    NASA Astrophysics Data System (ADS)

    Grant, Jonathan; Bathmann, Ulrich V.

    1987-06-01

    Filaments and extracellular material from colorless sulfur bacteria (Beggiatoa spp.) form extensive white sulfur mats on surface sediments of coastal, oceanic, and even deep-sea environments. These chemoautotrophic bacteria oxidize soluble reduced sulfur compounds and deposit elemental sulfur, enriching the sulfur content of surface sediment fivefold over that of deeper sediments. Laboratory flume experiments with Beggiatoa mats from an intertidal sandflat (Nova Scotia) demonstrated that even slight erosion of sediment causes a flux of 160 millimoles of sulfur per square meter per hour, two orders of magnitude greater than the flux produced by sulfur transformations involving either sulfate reduction or sulfide oxidation by benthic bacteria. These experiments indicate that resuspension of sulfur bacterial mats by waves and currents is a rapid mechanism by which sediment sulfur is recycled to the water column. Benthic communities thus lose an important storage intermediate for reduced sulfur as well as a high-quality bacterial food source for benthic grazers.

  3. Benthic macroinvertebrates as indicators of environmental deterioration in a large microtidal estuary.

    PubMed

    Wildsmith, M D; Rose, T H; Potter, I C; Warwick, R M; Clarke, K R

    2011-03-01

    This study tested the hypothesis that, during recent years, the benthic macroinvertebrate fauna of the large basin of the Swan-Canning Estuary has changed in ways consistent with deteriorating environmental conditions in that estuary. Between 1986/7 and 2003/4, the compositions of that fauna altered markedly at the species and even family levels. Thus, the densities and number of species of molluscs, and especially of crustaceans, which are particularly susceptible to environmental stress, declined, while those of the more tolerant polychaetes increased. However, taxonomic distinctness declined consistently only at one of the four widely-spaced sampling sites and the dispersion of samples did not differ markedly between periods, indicating that the benthic fauna has not undergone such extreme changes as in the nearby Peel-Harvey Estuary. It is thus proposed that benthic macroinvertebrates can act as important indicators of the severity of environmental degradation in microtidal estuaries in regions where such perturbations are increasing.

  4. Benthic recovery during open sea fish farming abatement in Western Mediterranean, Spain.

    PubMed

    Sanz-Lázaro, Carlos; Marin, Arnaldo

    2006-12-01

    Fish farming is an important source of organic matter input in coastal waters, which contributes to eutrophication. In this study, the macrofaunal benthic community was studied after the cessation of fish farming with the aim of improving our understanding of benthic succession and sediment recovery in a marine ecosystem. The results showed that the best environmental variables for assessing organic pollution were acid-volatile sulfides (AVS) and redox potential. Succession and recovery was best explained by macrofaunal analysis based on community composition as well as on trophic groups. The patterns of recovery differed between each impacted station. For this reason, succession could not be accurately predicted due to the unique environmental parameters and the singular community functional structure of each location. The Azti Marine Benthic Index (AMBI) proved its validity for assessing pollution but did not distinguish between successional stages.

  5. Contrasting time trends of organic contaminants in Antarctic pelagic and benthic food webs.

    PubMed

    van den Brink, Nico W; Riddle, Martin J; van den Heuvel-Greve, Martine; van Franeker, Jan Andries

    2011-01-01

    We demonstrate that pelagic Antarctic seabirds show significant decreases in concentrations of some persistent organic pollutants. Trends in Adélie penguins and Southern fulmars fit in a general pattern revealed by a broad literature review. Downward trends are also visible in pelagic fish, contrasting sharply with steady or increasing concentrations in Antarctic benthic organisms. Transfer of contaminants between Antarctic pelagic and benthic food webs is associated with seasonal sea-ice dynamics which may influence the balance between the final receptors of contaminants under different climatic conditions. This complicates the predictability of future trends of emerging compounds in the Antarctic ecosystem, such as of the brominated compounds that we detected in Antarctic petrels. The discrepancy in trends between pelagic and benthic organisms shows that Antarctic biota are still final receptors of globally released organic contaminants and it remains questionable whether the total environmental burden of contaminants in the Antarctic ecosystem is declining.

  6. Development of a regional littoral benthic macroinvertebrate multi-metric index (MMI) for lakes from the National Lakes Assessment

    EPA Science Inventory

    During the 2007 National Lakes Assessment (NLA) benthic macroinvertebrate samples were collected from the lake littoral zone. The purpose of the sampling was to assess the feasibility of a multi-metric index (MMI) to assess the condition of the littoral benthic macroinvertebrate...

  7. BENTHIC MICROALGAL CONTROL ON THE NUTRIENT FLUX IN INTER-TIDAL FLATS OF THE LOWER YAQUINA ESTUARY, OREGON

    EPA Science Inventory

    Three sites were selected across the intertidal zone of the lower Yaquina Bay to investigate the role of benthic microalgae in benthic nutrient fluxes. Study sites were selected where microalage were present but without seagrass or mud shrimp. Sediment columns were collected th...

  8. Spatial variation in organic matter utilization by benthic communities from Yura River-Estuary to offshore of Tango Sea, Japan

    NASA Astrophysics Data System (ADS)

    Antonio, Emily S.; Kasai, Akihide; Ueno, Masahiro; Won, Nam-il; Ishihi, Yuka; Yokoyama, Hisashi; Yamashita, Yoh

    2010-01-01

    We investigated the distribution of δ 13C and δ 15N of organic matter among benthic communities from the upper estuary of Yura River to offshore of Tango Sea, Japan, to determine spatial variation in utilization of organic matter by benthic communities. The δ 13C values of benthic animals ranged from -27 to -15‰ in the upper estuary, -21 to -15‰ in the lower estuary, -20 to -16‰ in the shallow coast (5-10 m depths), -18 to -16‰ in the deep coast (30-60 m depths) and -19 to -15‰ in offshore (100-150 m depths) stations. Adapting the dual isotope values to mixing models, we estimated the relative contributions of potential food sources to the benthos diet. Phytoplankton and macroalgae that intruded the estuary in summer were utilized as alternative food aside from the terrestrial-origin organic matter assimilated by the estuarine benthic consumers. Resuspended benthic microalgae were important source of energy in the shallow coastal stations, while abundant supply of phytodetritus fueled the deep coastal and offshore benthic food webs. Spatial difference in the diet of benthic communities depends largely on the shifts in the primary carbon source. Thus, benthic communities are important link of autochthonous/allochthonous production and secondary production in the continuous river-estuary-marine system.

  9. Reconnaissance of benthic invertebrates from tributary streams of the Yampa and North Platte River basins, northwestern Colorado

    SciTech Connect

    Britton, L.J.

    1983-01-01

    The benthic invertebrate communities in selected streams in coal mining areas were described and quantified. Field water-quality measurements, including water temperature, specific conductance, pH, dissolved oxygen, and bed material size were made to aid in assessing the relationship of stream water-quality conditions to benthic invertebrate communities. Density of organisms generally increased downstream in all streams sampled.

  10. CHANGES IN THE FRESHWATER BENTHIC COMMUNITY OF LAKE ONTARIO SINCE THE INVASION OF DREISSENA 1972-1997

    EPA Science Inventory

    Population changes of three major benthic taxa are discussed in relation to Dreissena spp. Lake Ontario was sampled pre-invasion (1972) and post-invasion (1994, 1997) for abundance of benthic organisms. In offshore sediments of Lake Ontario, neither species composition nor abunda...

  11. Marine Benthic Communities of Block Island and Rhode Island Sounds and What they're Good For

    EPA Science Inventory

    The benthic invertebrates of Block Island and Rhode Island Sounds include those adapted to near-shore habitats with variable temperature and salinity, mid-shelf species with narrower requirements, and boreal species that avoid elevated temperatures. Studies of benthic fauna in th...

  12. Low benthic respiration and nutrient flux at the highly productive Amundsen Sea Polynya, Antarctica

    NASA Astrophysics Data System (ADS)

    Kim, Sung-Han; Choi, Ayeon; Jin Yang, Eun; Lee, SangHoon; Hyun, Jung-Ho

    2016-01-01

    We investigated rates of total oxygen uptake (TOU) sulfate reduction (SRR), and benthic nutrient flux (BNF) in sediments of polynya (730-825 m water depth), ice shelf (1064 m water depth), and marginal sea-ice zone (530 m water depth) to evaluate the role of benthic mineralization in degrading organic material produced by primary production in the Amundsen Sea polynya (ASP), Antarctica. Despite high primary production (110 mmol C m-2 d-1) in the water column, benthic carbon mineralization in the ASP (average, 2.1±0.3 mmol C m-2 d-1) was strikingly lower than in other less productive polar regions, accounting for only 1.9% of primary production. Low sediment accumulation rates (0.18-0.20 cm yr-1) and sinking fluxes of organic matter likely caused the low oxygen consumption rates (2.44-3.11 mmol m-2 d-1) and low effluxes of dissolved inorganic nitrogen (0.12-0.13 mmol m-2 d-1) and phosphate (0.017-0.018 mmol m-2 d-1) in the ASP. Carbon oxidation by sulfate reduction (0.11-0.19 mmol C m-2 d-1) comprised only 10% of total benthic mineralization, indicating that anaerobic C oxidation plays a minor role in total C oxidation. Our results, including low sediment accumulation rates and benthic metabolic rates, suggest that most organic carbon produced by Phaeocystis blooms would be respired to CO2 in the water column, and thus the organic carbon reaching the sediment is not adequate to stimulate benthic metabolism in the ASP.

  13. Necrophagy by a benthic omnivore influences biomagnification of methylmercury in fish.

    PubMed

    Bowling, Anna M; Hammerschmidt, Chad R; Oris, James T

    2011-04-01

    Omnivory has an important role in the movement of energy, nutrients, and contaminants between benthic and pelagic food webs. While top-predator fish are known to supplement a mostly piscivorous diet with benthic organisms, a more obscure benthic-pelagic coupling occurs when benthic invertebrates forage on fish carcasses, referred to as necrophagy. The combination of these two benthic-pelagic links, top-predator fish feeding on benthic organisms that have fed on dead fish, can generate a trophic feedback cycle that conserves energy and nutrients and may have implications for biomagnification of methylmercury (MeHg) in fish. We investigated the role of necrophagy by crayfish (Procambarus clarkii), via a trophic feedback cycle, on the biomagnification of MeHg in largemouth bass (Micropterus salmoides), a cosmopolitan top predator fish known to feed on crayfish. Controlled laboratory tests quantified the uptake of MeHg by both organisms from artificial and natural food (whole crayfish or bass tissue). Assimilation efficiency (AE) of MeHg was greater for bass fed crayfish (79±0.5%) than those fed artificial food (60±3%). Furthermore, AE of MeHg was greatest for largemouth bass fed crayfish that fed on MeHg-dosed dead fish (i.e., trophic feedback cycle; 94±17%). A model, parameterized with results of the laboratory experiments, was used to make steady-state projections of MeHg biomagnification factors. Model projections also indicate that MeHg biomagnification would be greatest for largemouth bass from a trophic feedback cycle. These results suggest that food web ecology has an important role in determining MeHg levels in predatory fish and underscore the need for further investigation into the magnitude that necrophagy may affect MeHg biomagnification in aquatic systems. PMID:21356175

  14. Campanian-Maastrichtian intermediate- to deep-water changes in the high latitudes: Benthic foraminiferal evidence

    NASA Astrophysics Data System (ADS)

    Koch, Mirjam C.; Friedrich, Oliver

    2012-06-01

    During the latest Cretaceous cooling phase, a positive shift in benthic foraminiferal δ18O values lasting about 1.5 Myr (71.5-70 Ma) can be observed at a global scale (Campanian-Maastrichtian Boundary Event, CMBE). This δ18O excursion is interpreted as being influenced by a change in intermediate- to deep-water circulation or by temporal build-up of Antarctic ice sheets. Here we test whether benthic foraminiferal assemblages from a southern high-latitudinal site near Antarctica (ODP Site 690) are influenced by the CMBE. If the δ18O transition reflects a change in intermediate- to deep-water circulation from low-latitude to high-latitude water masses, then this change would result in cooler temperatures, higher oxygen concentration, and possibly lower organic-matter flux at the seafloor, resulting in a major benthic foraminiferal assemblage change. If, however, the δ18O transition was mainly triggered by ice formation, no considerable compositional difference in benthic foraminiferal assemblages would be expected. Our data show a separation of the studied succession into two parts with distinctly different benthic foraminiferal assemblages. Species dominating the older part (73.0-70.5 Ma) tolerate less bottom water oxygenation and are typical components of low-latitude assemblages. In contrast, the younger part (70.0-68.0 Ma) is characterized by species that indicate well-oxygenated bottom waters and species common in high-latitude assemblages. We interpret the observed change in benthic foraminiferal assemblages toward a well-oxygenated environment to reflect the onset of a shift from low-latitude toward high-latitude dominated intermediate- to deep-water sources. This implies that a change in oceanic circulation was at least a major component of the CMBE.

  15. Crater lake cichlids individually specialize along the benthic-limnetic axis.

    PubMed

    Kusche, Henrik; Recknagel, Hans; Elmer, Kathryn Rebecca; Meyer, Axel

    2014-04-01

    A common pattern of adaptive diversification in freshwater fishes is the repeated evolution of elongated open water (limnetic) species and high-bodied shore (benthic) species from generalist ancestors. Studies on phenotype-diet correlations have suggested that population-wide individual specialization occurs at an early evolutionary and ecological stage of divergence and niche partitioning. This variable restricted niche use across individuals can provide the raw material for earliest stages of sympatric divergence. We investigated variation in morphology and diet as well as their correlations along the benthic-limnetic axis in an extremely young Midas cichlid species, Amphilophus tolteca, endemic to the Nicaraguan crater lake Asososca Managua. We found that A. tolteca varied continuously in ecologically relevant traits such as body shape and lower pharyngeal jaw morphology. The correlation of these phenotypes with niche suggested that individuals are specialized along the benthic-limnetic axis. No genetic differentiation within the crater lake was detected based on genotypes from 13 microsatellite loci. Overall, we found that individual specialization in this young crater lake species encompasses the limnetic-as well as the benthic macro-habitat. Yet there is no evidence for any diversification within the species, making this a candidate system for studying what might be the early stages preceding sympatric divergence. A common pattern of adaptive diversification in freshwater fishes is the repeated evolution of open water (limnetic) species and of shore (benthic) species. Individual specialization can reflect earliest stages of evolutionary and ecological divergence. We here demonstrate individual specialization along the benthic-limnetic axis in a young adaptive radiation of crater lake cichlid fishes.

  16. Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

    NASA Astrophysics Data System (ADS)

    Manasa, M.; Saraswat, Rajeev; Nigam, Rajiv

    2016-04-01

    Temporal changes in benthic foraminiferal morpho-groups were suggested as an effective proxy to reconstruct past monsoon intensity from the Arabian Sea. Here, in order to test the applicability of temporal variation in morpho-groups to reconstruct past monsoon intensity from the Bay of Bengal, we have documented recent benthic foraminiferal distribution from the continental shelf region of the northwestern Bay of Bengal. Based on the external morphology, benthic foraminifera were categorized into rounded symmetrical (RSBF) and angular asymmetrical benthic foraminifera (AABF). Additionally, a few other dominant groups were also identified based on test composition (agglutinated, calcareous) and abundance (Asterorotalids and Nonions). The relative abundance of each group was compared with the ambient physico-chemical conditions, including dissolved oxygen, organic matter, salinity and temperature. We report that the RSBF are abundant in comparatively warm and well oxygenated waters of low salinity, suggesting a preference for high energy environment, whereas AABF dominate relatively cold, hypersaline deeper waters with low dissolved oxygen, indicating a low energy environment. The agglutinated foraminifera, Asterorotalids and Nonions dominate shallow water, low salinity regions, whereas the calcareous benthic foraminiferal abundance increases away from the riverine influx regions. Food availability, as estimated from organic carbon abundance in sediments, has comparatively less influence on faunal distribution in the northwestern Bay of Bengal, as compared to dissolved oxygen, temperature and salinity. We conclude that the factors associated with freshwater influx affect the distribution of benthic foraminiferal morpho-groups in the northwestern Bay of Bengal and thus it can be used to reconstruct past monsoon intensity from the Bay of Bengal.

  17. Benthic marine calcifiers coexist with CaCO3-undersaturated seawater worldwide

    NASA Astrophysics Data System (ADS)

    Lebrato, M.; Andersson, A. J.; Ries, J. B.; Aronson, R. B.; Lamare, M. D.; Koeve, W.; Oschlies, A.; Iglesias-Rodriguez, M. D.; Thatje, S.; Amsler, M.; Vos, S. C.; Jones, D. O. B.; Ruhl, H. A.; Gates, A. R.; McClintock, J. B.

    2016-07-01

    Ocean acidification and decreasing seawater saturation state with respect to calcium carbonate (CaCO3) minerals have raised concerns about the consequences to marine organisms that build CaCO3 structures. A large proportion of benthic marine calcifiers incorporate Mg2+ into their skeletons (Mg-calcite), which, in general, reduces mineral stability. The relative vulnerability of some marine calcifiers to ocean acidification appears linked to the relative solubility of their shell or skeletal mineralogy, although some organisms have sophisticated mechanisms for constructing and maintaining their CaCO3 structures causing deviation from this dependence. Nevertheless, few studies consider seawater saturation state with respect to the actual Mg-calcite mineralogy (ΩMg-x) of a species when evaluating the effect of ocean acidification on that species. Here, a global dataset of skeletal mole % MgCO3 of benthic calcifiers and in situ environmental conditions spanning a depth range of 0 m (subtidal/neritic) to 5600 m (abyssal) was assembled to calculate in situ ΩMg-x. This analysis shows that 24% of the studied benthic calcifiers currently experience seawater mineral undersaturation (ΩMg-x < 1). As a result of ongoing anthropogenic ocean acidification over the next 200 to 3000 years, the predicted decrease in seawater mineral saturation will expose approximately 57% of all studied benthic calcifying species to seawater undersaturation. These observations reveal a surprisingly high proportion of benthic marine calcifiers exposed to seawater that is undersaturated with respect to their skeletal mineralogy, underscoring the importance of using species-specific seawater mineral saturation states when investigating the impact of CO2-induced ocean acidification on benthic marine calcification.

  18. Effects of management legacies on stream fish and aquatic benthic macroinvertebrate assemblages.

    PubMed

    Quist, Michael C; Schultz, Randall D

    2014-09-01

    Fish and benthic macroinvertebrate assemblages often provide insight on ecological conditions for guiding management actions. Unfortunately, land use and management legacies can constrain the structure of biotic communities such that they fail to reflect habitat quality. The purpose of this study was to describe patterns in fish and benthic macroinvertebrate assemblage structure, and evaluate relationships between biota and habitat characteristics in the Chariton River system of south-central Iowa, a system likely influenced by various potential management legacies (e.g., dams, chemical removal of fishes). We sampled fishes, benthic macroinvertebrates, and physical habitat from a total of 38 stream reaches in the Chariton River watershed during 2002-2005. Fish and benthic macroinvertebrate assemblages were dominated by generalist species tolerant of poor habitat quality; assemblages failed to show any apparent patterns with regard to stream size or longitudinal location within the watershed. Metrics used to summarize fish assemblages and populations [e.g., presence-absence, relative abundance, Index of Biotic Integrity for fish (IBIF)] were not related to habitat characteristics, except that catch rates of piscivores were positively related to the depth and the amount of large wood. In contrast, family richness of benthic macroinvertebrates, richness of Ephemeroptera, Trichoptera, and Plecoptera taxa, and IBI values for benthic macroinvertebrates (IBIBM) were positively correlated with the amount of overhanging vegetation and inversely related to the percentage of fine substrate. A long history of habitat alteration by row-crop agriculture and management legacies associated with reservoir construction has likely resulted in a fish assemblage dominated by tolerant species. Intolerant and sensitive fish species have not recolonized streams due to downstream movement barriers (i.e., dams). In contrast, aquatic insect assemblages reflected aquatic habitat, particularly

  19. Effects of Management Legacies on Stream Fish and Aquatic Benthic Macroinvertebrate Assemblages

    NASA Astrophysics Data System (ADS)

    Quist, Michael C.; Schultz, Randall D.

    2014-09-01

    Fish and benthic macroinvertebrate assemblages often provide insight on ecological conditions for guiding management actions. Unfortunately, land use and management legacies can constrain the structure of biotic communities such that they fail to reflect habitat quality. The purpose of this study was to describe patterns in fish and benthic macroinvertebrate assemblage structure, and evaluate relationships between biota and habitat characteristics in the Chariton River system of south-central Iowa, a system likely influenced by various potential management legacies (e.g., dams, chemical removal of fishes). We sampled fishes, benthic macroinvertebrates, and physical habitat from a total of 38 stream reaches in the Chariton River watershed during 2002-2005. Fish and benthic macroinvertebrate assemblages were dominated by generalist species tolerant of poor habitat quality; assemblages failed to show any apparent patterns with regard to stream size or longitudinal location within the watershed. Metrics used to summarize fish assemblages and populations [e.g., presence-absence, relative abundance, Index of Biotic Integrity for fish (IBIF)] were not related to habitat characteristics, except that catch rates of piscivores were positively related to the depth and the amount of large wood. In contrast, family richness of benthic macroinvertebrates, richness of Ephemeroptera, Trichoptera, and Plecoptera taxa, and IBI values for benthic macroinvertebrates (IBIBM) were positively correlated with the amount of overhanging vegetation and inversely related to the percentage of fine substrate. A long history of habitat alteration by row-crop agriculture and management legacies associated with reservoir construction has likely resulted in a fish assemblage dominated by tolerant species. Intolerant and sensitive fish species have not recolonized streams due to downstream movement barriers (i.e., dams). In contrast, aquatic insect assemblages reflected aquatic habitat, particularly

  20. Benthic Foraminifera, Food in the Deep Sea, and Limits to Bentho-Pelagic Coupling

    NASA Astrophysics Data System (ADS)

    Thomas, E.; Boscolo-Galazzo, F.; Arreguin-Rodrigu, G. J.; Ortiz, S.; Alegret, L.

    2015-12-01

    The deep-sea is the largest habitat on Earth, contains highly diverse biota, but is very little known. Many of its abundant benthic biota (e.g., nematodes) are not preserved in the fossil record. Calcareous and agglutinated benthic foraminifera (unicellular eukaryotes, Rhizaria; efficient dispersers) and ostracodes (Animalia, Crustacea; non-efficient dispersers) are the most common organisms providing a fossil record of deep-sea environments. Very little food is supplied to the deep-sea, because organic matter produced by photosynthesis is largely degraded before it arrives at the seafloor. Only a few % of organic matter is carried to the ocean bottom by 'marine snow', with its particle size and behavior in the water column controlled by surface ecosystem structure, including type of dominant primary producers (diatoms, cyanobacteria). Food supply and its seasonality are generally seen as the dominant control on benthic assemblages (combined with oxygenation), providing bentho-pelagic coupling between primary and benthic productivity. Benthic foraminiferal assemblages (composition and density) thus are used widely to estimate past productivity, especially during episodes of global climate change, ocean acidification, and mass extinction of primary producers. We show that some environmental circumstances may result in interrupting bentho-pelagic coupling, e.g. through lateral supply of organic matter along continental margins (adding more refractory organic matter), through trophic focusing and/or fine particle winnowing on seamounts (giving an advantage to suspension feeders), and through carbonate undersaturation (giving advantage to infaunal over epifaunal calcifyers). In addition, increased remineralization of organic matter combined with increased metabolic rates may cause assemblages to reflect more oligotrophic conditions at stable primary productivity during periods of global warming. As a result, benthic foraminiferal accumulation rates must be carefully

  1. Carbon transport in the bottom boundary layer. Final report

    SciTech Connect

    Lohrenz, S.E.; Asper, V.L.

    1997-09-01

    The authors objective was to characterize distributions of chloropigment fluorescence in relation to physical processes in the benthic boundary layer in support of the Department of Energy (DOE) Ocean Margins Program`s (OMP) goal of quantifying carbon transport across the continental shelf. Their approach involved participation in the Ocean Margins Program (OMP) field experiment on the continental shelf off Cape Hatteras by conducting multi-sensor fluorescence measurements of photosynthetic pigments. Specific tasks included (1) pre- and post-deployment calibration of multiple fluorescence sensors in conjunction with Woods Hole personnel; (2) collection and analysis of photosynthetic pigment concentrations and total particulate carbon in water column samples to aid in interpretation of the fluorescence time-series during the field experiment; (3) collaboration in the analysis and interpretation of 1994 and 1996 time-series data in support of efforts to quantify pigment and particulate organic carbon transport on the continental shelf off Cape Hatteras. This third component included analysis of data obtained with a multi-sensor fiber-optic fluorometer in the benthic boundary layer of the inner shelf off Cape Hatteras during summer 1994.

  2. Interactions between benthic predators and zooplanktonic prey are affected by turbulent waves.

    PubMed

    Robinson, H E; Finelli, C M; Koehl, M A R

    2013-11-01

    Predators capture prey in complex and variable environments. In the ocean, bottom-dwelling (benthic) organisms are subjected to water currents, waves, and turbulent eddies. For benthic predators that feed on small animals carried in the water (zooplankton), flow not only delivers prey, but can also shape predator-prey interactions. Benthic passive suspension feeders collect prey delivered by movement of ambient water onto capture-surfaces, whereas motile benthic predators, such as burrow-dwelling fish, dart out to catch passing zooplankton. How does the flow of ambient water affect these contrasting modes of predation by benthic zooplanktivores? We studied the effects of turbulent, wavy flow on the encounter, capture, and retention of motile zooplanktonic prey (copepods, Acartia spp.) by passive benthic suspension feeders (sea anemones, Anthopleura elegantissima). Predator-prey interactions were video-recorded in a wave-generating flume under two regimes of oscillating flow with different peak wave velocities and levels of turbulent kinetic energy ("weak" and "strong" waves). Rates of encounter (number of prey passing through a sea anemone's capture zone per time), capture (prey contacting and sticking to tentacles per time), and retention (prey retained on tentacles, without struggling free or washing off, per time) were measured at both strengths of waves. Strong waves enhanced encounter rates both for dead copepods and for actively swimming copepods, but there was so much variability in the behavior of the live prey that the effect of wave strength on encounter rates was not significant. Trapping efficiency (number of prey retained per number encountered) was the same in both flow regimes because, although fewer prey executed maneuvers to escape capture in strong waves, more of the captured prey was washed off the predators' tentacles. Although peak water velocities and turbulence of waves did not affect feeding rates of passive suspension-feeding sea anemones

  3. An unusually large phytoplankton spring bloom drives rapid changes in benthic diversity and ecosystem function

    NASA Astrophysics Data System (ADS)

    Zhang, Qingtian; Warwick, Richard M.; McNeill, Caroline L.; Widdicombe, Claire E.; Sheehan, Aaron; Widdicombe, Stephen

    2015-09-01

    In 2012, the Western English Channel experienced an unusually large and long-lived phytoplankton spring bloom. When compared with data from the past 20 years, average phytoplankton biomass at Station L4 (part of the Western Channel Observatory) was approximately 3× greater and lasted 50% longer than any previous year. Regular (mostly weekly) box core samples were collected from this site before, during and after the bloom to determine its impact on macrofaunal abundance, diversity, biomass, community structure and function. The spring bloom of 2012 was shown to support a large and rapid response in the majority of benthic taxa and functional groups. However, key differences in the precise nature of this response, as well as in its timing, was observed between different macrofauna feeding groups. Deposit feeders responded almost instantly at the start of the bloom, primarily thorough an increase in abundance. Suspension feeders and opportunistic/predatory/carnivorous taxa responded slightly more slowly and primarily with an increase in biomass. At the end of the bloom a rapid decline in macrobenthic abundance, diversity and biomass closely followed the decline in phytoplankton biomass. With suspension feeders showing evidence of this decline a few weeks before deposit feeders, it was concluded that this collapse in benthic communities was driven primarily by food availability and competition. However, it is possible that environmental hypoxia and the presence of toxic benthic cyanobacteria could also have contributed to this decline. This study shows evidence for strong benthic-pelagic coupling at L4; a shallow (50 m), coastal, fine-sand habitat. It also demonstrates that in such habitats, it is not just planktonic organisms that demonstrate clear community phenology. Different functional groups within the benthic assemblage will respond to the spring bloom in specific manner, with implications for key ecosystem functions and processes, such as secondary production

  4. Distribution and abundance of benthic organisms in the Sacramento River, California

    USGS Publications Warehouse

    Ferreira, Rodger F.; Green, D. Brady

    1977-01-01

    General comparisons were made between benthic organism samples collected in 1960-61 and 1972-73 from five sites in the Sacramento River between Red Bluff and Knights Landing, Calif. The composition of benthic organisms from both collection periods was similar. The 1972-73 data showed variable patterns in monthly changes at each site and downstream changes each month with number of organisms per square meter, number of taxa per square meter, and diversity index. Generally, the mean number of taxa per square meter and diversity index for all sampling periods were higher in the upper reach than the lower reach of the Sacramento River. (Woodard-USGS)

  5. The distribution and diversity of benthic macroinvertebrate fauna in Pondicherry mangroves, India

    PubMed Central

    2013-01-01

    Background Species distribution, abundance and diversity of mangrove benthic macroinvertebrate fauna and the relationships to environmental conditions are important parts of understanding the structure and function of mangrove ecosystems. In this study seasonal variation in the distribution of macrobenthos and related environmental parameters were explored at four mangrove stations along the Pondicherry coast of India, from September 2008 to July 2010. Multivariate statistical analyses, including cluster analysis, principal component analysis and non-multidimensional scales plot were employed to help define trophic status, water quality and benthic characteristic at the four monitoring stations. Results Among the 528 samples collected over 168 ha of mangrove forest 76 species of benthic macroinvertebrate fauna were identified. Macrofauna were mainly composed of deposit feeders, dominated numerically by molluscs and crustaceans. Statistical analyses yielded the following descriptors of benthic macroinvertebrate fauna species distribution: densities between 140–1113 ind. m-2, dominance 0.17-0.50, diversity 1.80-2.83 bits ind-1, richness 0.47-0.74 and evenness 0.45-0.72, equitability 0.38-0.77, berger parker 0.31-0.77 and fisher alpha 2.46-5.70. Increases of species diversity and abundance were recorded during the post monsoon season at station 1 and the lowest diversity was recorded at station 2 during the monsoon season. The pollution indicator organisms Cassidula nucleus, Melampus ceylonicus, Sphaerassiminea minuta were found only at the two most polluted regions, i.e. stations 3 and 4. Benthic macroinvertebrate fauna abundances were inversely related to salinity at the four stations, Based on Bray-Curtis similarity through hierarchical clustering implemented in PAST, it was possible to define three distinct benthic assemblages at the stations. Conclusions From a different multivariate statistical analysis of the different environmental parameters regarding

  6. Analysis of Illumina MiSeq Metabarcoding Data: Application to Benthic Indices for Environmental Monitoring.

    PubMed

    Aylagas, Eva; Rodríguez-Ezpeleta, Naiara

    2016-01-01

    This protocol details the analysis of Illumina MiSeq amplicon libraries derived from marine benthic macroinvertebrate samples and based on two barcodes of the mitochondrial cytochrome oxidase 1 (CO1) gene: a "short region," covered by overlapping forward and reverse reads and a "long region" for which forward and reverse reads do not overlap. Aside from providing guidelines for analyzing both types of amplicons, we show how amplicon reads can be used for the calculation of benthic indices for environmental monitoring. PMID:27460382

  7. Sequential sampling: cost-effective approach for monitoring benthic macroinvertebrates in environmental impact assessements

    SciTech Connect

    Resh, V.H.; Price, D.G.

    1984-01-01

    Sequential sampling is a method for monitoring benthic macroinvertebrates that can significantly reduce the number of samples required to reach a decision, and consequently, decrease the cost of benthic sampling in environmental impact assessments. Rather than depending on a fixed number of samples, this analysis cumulatively compares measured parameter values (for example, density, community diversity) from individual samples, with thresholds that are based on specified degrees of precision. In addition to reducing sample size, a monitoring program based on sequential sampling can provide clear-cut decisions as to whether a priori-defined changes in the measured parameter(s) have or have not occurred.

  8. Correspondence of stream benthic invertebrate assemblages to regional classification schemes in Missouri

    USGS Publications Warehouse

    Rabeni, C.F.; Doisy, K.E.

    2000-01-01

    Benthic invertebrates from 44 reference streams throughout the state of Missouri were examined for their concordance with established regionalization systems, both aquatic and terrestrial. Invertebrate assemblages coincided nicely with Pflieger's established aquatic faunal regions system, expanding its generality to more than fish assemblages. Our benthic invertebrate and Pflieger's fish assemblages coincided well with both Bailey's ecological sections and Omernik's ecoregions. Subregionalization using Pflieger's subregions and Bailey's subsections further reduced unexplained variation and is recommended for use wherever possible. The concordance of the aquatic fauna and terrestrial features implies the possibility of coordinated regional management among different natural resource disciplines.

  9. Effects of gut sediment contents on measurements of metal levels in benthic invertebrates - a cautionary note

    SciTech Connect

    Chapman, P.M.

    1985-09-01

    Studies of heavy metal levels in benthic organisms typically do not correct for gut sediment metal levels other than by allowing a period of depuration in clean water. The effectiveness of depuration has recently been questioned in British Columbia in the particular case of the marine clam Yoldia. In light of this controversy, it appears appropriate to present data from a study of heavy metal levels in sediments and benthic organisms in the Lower Fraser River, BC, regarding the effects of gut sediment contents.

  10. Benthic macrofauna and ancillary data for San Francisco Bay, California, March to November 1987

    USGS Publications Warehouse

    Schemel, Laurence E.; Ota, Allan Y.; Harmon, J.G.; Shay, J.M.; Adorado, R.N.

    1988-01-01

    Benthic macrofauna and ancillary data were collected during 1987 as part of the U.S. Geological Survey Regional Effects Monitoring Program in San Francisco Bay, California. Data were collected during five cruises at 2-month intervals from March through November. Benthic macrofauna for identification of species and sediment for size analysis were sampled at eight stations. Ancillary data, which consisted of salinity, temperature, dissolved-oxygen concentrations, and suspended sediment, were collected at 12 stations. Salinity and temperature were measured at three stations that coincided with continuous water quality monitors. Abundances and geographical distributions of a newly introduced species of clam were measured. (USGS)

  11. Nutrient and suspended-sediment concentrations and loads and benthic-invertebrate data for tributaries to the St. Croix River, Wisconsin and Minnesota, 1997-99

    USGS Publications Warehouse

    Lenz, Bernard N.; Robertson, Dale M.; Fallon, James D.; Ferrin, Randy

    2001-01-01

    Benthic invertebrates were sampled and indices of water quality were calculated at 16 tributaries in fall 1999. Benthic invertebrate indices indicated excellent to good water quality at all tributaries except Valley Creek, Willow River, and Kettle River. No relations were found between benthic invertebrate indices and the calculated and estimated 1999 annual tributary loads and yields.

  12. Benthic infaunal community structuring in an acidified tropical estuarine system

    PubMed Central

    2014-01-01

    Background Recent studies suggest that increasing ocean acidification (OA) should have strong direct and indirect influences on marine invertebrates. While most theory and application for OA is based on relatively physically-stable oceanic ecological systems, less is known about the effects of acidification on nearshore and estuarine systems. Here, we investigated the structuring of a benthic infaunal community in a tropical estuarine system, along a steep salinity and pH gradient, arising largely from acid-sulphate groundwater inflows (Sungai Brunei Estuary, Borneo, July 2011- June 2012). Results Preliminary data indicate that sediment pore-water salinity (range: 8.07 - 29.6 psu) declined towards the mainland in correspondence with the above-sediment estuarine water salinity (range: 3.58 – 31.2 psu), whereas the pore-water pH (range: 6.47- 7.72) was generally lower and less variable than the estuarine water pH (range: 5.78- 8.3), along the estuary. Of the thirty six species (taxa) recorded, the polychaetes Neanthes sp., Onuphis conchylega, Nereididae sp. and the amphipod Corophiidae sp., were numerically dominant. Calcified microcrustaceans (e.g., Cyclopoida sp. and Corophiidae sp.) were abundant at all stations and there was no clear distinction in distribution pattern along the estuarine between calcified and non-calcified groups. Species richness increased seawards, though abundance (density) showed no distinct directional trend. Diversity indices were generally positively correlated (Spearman’s rank correlation) with salinity and pH (p <0.05) and negatively with clay and organic matter, except for evenness values (p >0.05). Three faunistic assemblages were distinguished: (1) nereid-cyclopoid-sabellid, (2) corophiid-capitellid and (3) onuphid- nereid-capitellid. These respectively associated with lower salinity/pH and a muddy bottom, low salinity/pH and a sandy bottom, and high salinity/pH and a sandy bottom. However, CCA suggested that species distribution

  13. Benthic invertebrate bioassays with toxic sediment and pore water

    USGS Publications Warehouse

    Giesy, John P.; Rosiu, Cornell J.; Graney, Robert L.; Henry, Mary G.

    1990-01-01

    The relative sensitivities of bioassays to determine the toxicity of sediments were investigated and three methods of making the sample dilutions required to generate dose-response relationships were compared. The assays studied were: (a) Microtox®, a 15-min assay ofPhotobacterium phosphoreum bioluminescence inhibition by pore water; (b) 48-h Daphnia magnalethality test in pore water; (c) 10-d subchronic assay of lethality to and reduction of weight gain by Chironomus tentans performed in either whole sediment or pore water; (d) 168-h acute lethality assay of Hexagenia limbata in either whole sediment or pore water. The three methods of diluting sediments were: (a) extracting pore water from the toxic location and dilution with pore water from the control station; (b) diluting whole sediment from the toxic location with control whole sediment from a reference location, then extracting pore water; and (c) diluting toxic, whole sediment with whole sediment from a reference location, then using the whole sediment in bioassays. Based on lethality, H. limbata was the most sensitive organism to the toxicity of Detroit River sediment. Lethality of D. magna in pore water was similar to that of H. limbata in whole sediment and can be used to predict effects of whole sediment toxicity to H. limbata. The concentration required to cause a 50% reduction in C. tentans growth (10-d EC50) was approximately that which caused 50% lethality of D. magna (48-h LC50) and was similar to the toxicity that restricts benthic invertebrate colonization of contaminated sediments. While the three dilution techniques gave similar results with some assays, they gave very different results in other assays. The dose-response relationships determined by the three dilution techniques would be expected to vary with sediment, toxicant and bioassay type, and the dose-response relationship derived from each technique needs to be interpreted accordingly.

  14. Modelling COD and N removal in the water and in the benthic biofilm for the River Wupper in Germany.

    PubMed

    Wichern, M; Kehl, O; Erbe, V; Luebken, M; Wilderer, P A

    2006-01-01

    The River Wupper, a tributary of the River Rhine, is at several locations influenced by anthropogenous nitrogen input, hydraulic structures, and influents from other tributaries. These influences have an impact both on the water quality and on the hydrodynamic conditions. The model approaches used for this article are based on work of Rauch et al. and the River Water Quality Model No. 1; they allow the simulation of the nitrogen conversion in the River Wupper. They are compatible with the activated sludge models and can thus be used also for integrated approaches. The calibration and validation of the model was realized using actual data of the River Wupper over a length of 60 km with one dam, 10 weirs, three wastewater treatment plants and 11 tributaries. The model considers the nitrogen conversion and COD removal and has a strong focus on biofilm processes in the benthic zone. Additional information is given about the sedimentation processes, the physical oxygen input processes, biofilm detachment processes, molecular diffusion, the influence of the laminar border layer and the changing of COD fractions and biofilm densities.

  15. Development of bacteria and benthic total maximum daily loads: a case study, Linville Creek, Virginia.

    PubMed

    Benham, Brian L; Brannan, Kevin M; Yagow, Gene; Zeckoski, Rebecca W; Dillaha, Theo A; Mostaghimi, Saied; Wynn, Jeff W

    2005-01-01

    Two total maximum daily load (TMDL) studies were performed for Linville Creek in Rockingham County, Virginia, to address bacterial and benthic impairments. The TMDL program is an integrated watershed management approach required by the Clean Water Act. This paper describes the procedures used by the Center for TMDL and Watershed Studies at Virginia Tech to develop the Linville Creek TMDLs and discusses the key lessons learned from and the ramifications of the procedures used in these and other similar TMDL studies. The bacterial impairment TMDL was developed using the Hydrological Simulation Program-Fortran (HSPF). Fecal coliform loads were estimated through an intensive source characterization process. The benthic impairment TMDL was developed using the Generalized Watershed Loading Function (GWLF) model and the reference watershed approach. The bacterial TMDL allocation scenario requires a 100% reduction in cattle manure direct-deposits to the stream, a 96% reduction in nonpoint-source loadings to the land surface, and a 95% reduction in wildlife direct-deposits to the stream. Sediment was identified as the primary benthic stressor. The TMDL allocation scenario for the benthic impairment requires an overall reduction of 12.3% of the existing sediment loads. Despite the many drawbacks associated with using watershed-scale models like HSPF and GWLF to develop TMDLs, the detailed watershed and pollutant-source characterization required to use these and similar models creates information that stakeholders need to select appropriate corrective measures to address the cause of the water quality impairment when implementing the TMDL. PMID:16151238

  16. Autonomous video camera system for monitoring impacts to benthic habitats from demersal fishing gear, including longlines

    NASA Astrophysics Data System (ADS)

    Kilpatrick, Robert; Ewing, Graeme; Lamb, Tim; Welsford, Dirk; Constable, Andrew

    2011-04-01

    Studies of the interactions of demersal fishing gear with the benthic environment are needed in order to manage conservation of benthic habitats. There has been limited direct assessment of these interactions through deployment of cameras on commercial fishing gear especially on demersal longlines. A compact, autonomous deep-sea video system was designed and constructed by the Australian Antarctic Division (AAD) for deployment on commercial fishing gear to observe interactions with benthos in the Southern Ocean finfish fisheries (targeting toothfish, Dissostichus spp). The Benthic Impacts Camera System (BICS) is capable of withstanding depths to 2500 m, has been successfully fitted to both longline and demersal trawl fishing gear, and is suitable for routine deployment by non-experts such as fisheries observers or crew. The system is entirely autonomous, robust, compact, easy to operate, and has minimal effect on the performance of the fishing gear it is attached to. To date, the system has successfully captured footage that demonstrates the interactions between demersal fishing gear and the benthos during routine commercial operations. It provides the first footage demonstrating the nature of the interaction between demersal longlines and benthic habitats in the Southern Ocean, as well as showing potential as a tool for rapidly assessing habitat types and presence of mobile biota such as krill ( Euphausia superba).

  17. 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...

  18. Macroecological drivers of archaea and bacteria in benthic deep-sea ecosystems

    PubMed Central

    Danovaro, Roberto; Molari, Massimiliano; Corinaldesi, Cinzia; Dell’Anno, Antonio

    2016-01-01

    Bacteria and archaea dominate the biomass of benthic deep-sea ecosystems at all latitudes, playing a crucial role in global biogeochemical cycles, but their macroscale patterns and macroecological drivers are still largely unknown. We show the results of the most extensive field study conducted so far to investigate patterns and drivers of the distribution and structure of benthic prokaryote assemblages from 228 samples collected at latitudes comprising 34°N to 79°N, and from ca. 400- to 5570-m depth. We provide evidence that, in deep-sea ecosystems, benthic bacterial and archaeal abundances significantly increase from middle to high latitudes, with patterns more pronounced for archaea, and particularly for Marine Group I Thaumarchaeota. Our results also reveal that different microbial components show varying sensitivities to changes in temperature conditions and food supply. We conclude that climate change will primarily affect deep-sea benthic archaea, with important consequences on global biogeochemical cycles, particularly at high latitudes. PMID:27386507

  19. Benthic macroinvertebrate surveys in Chequamegon Bay in support of invasive species early detection research

    EPA Science Inventory

    This presentation describes the impetus and approach for MED invasive species early detection research generally and presents preliminary results concerning benthic composition and non-native species found in the 2013 Chequamegon Bay survey. The audience is a group of researchers...

  20. Eutrophication and Hypoxia Degrade Ecosystem Functions and Services of Narragansett Bay Benthic Communities

    EPA Science Inventory

    Excessive input of nitrogen to estuaries and coastal waters leads to eutrophication; the resulting organic matter over-enrichment of the sediments and seasonal hypoxia of the bottom water have well-known deleterious effects on benthic community biodiversity, abundance, and biomas...

  1. DMSP in Corals and Benthic Algae from the Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    Broadbent, A. D.; Jones, G. B.; Jones, R. J.

    2002-10-01

    In this study the first measurements of DMSP in six species of corals and ten species of benthic algae collected from four coral reefs in the Great Barrier Reef are reported, together with DMSP measurements made on cultured zooxanthellae. Concentrations ranged from 21 to 3831 (mean=743) fmol DMSP zooxanthellae -1 in corals, 0·16 to 2·96 nmol DMSP cm -2 (mean=90) for benthic macroalgae, and 48-285 fmol DMSP zooxanthellae -1 (mean=153) for cultured zooxanthellae. The highest concentrations of DMSP in corals occurred in Acropora formosa (mean=371 fmol DMSP zooxanthellae -1) and Acropora palifera (mean=3341 fmol DMSP zooxanthellae -1) with concentrations in A. palifera the highest DMSP concentrations reported in corals examined to date. As well as inter-specific differences in DMSP, intra-specific variation was also observed. Adjacent colonies of A. formosa that are known to have different thermal bleaching thresholds and morphologically distinct zooxanthellae, were also observed to have different DMSP concentrations, with the zooxanthellae in the colony that bleached containing DMSP at an average concentration of 436 fmol zooxanthellae -1, whilst the non-bleaching colony contained DMSP at an average concentration of 171 fmol zooxanthellae -1. The results of the present study have been used to calculate the area normalized DMSP concentrations in benthic algae (mean=0·015 mmol m -2) and corals (mean=2·22 mmol m -2) from the GBR. This data indicates that benthic algae and corals are a significant reservoir of DMSP in GBR waters.

  2. Benthic diatom composition in wet and dry isolated forested wetlands: implications for monitoring and assessment

    EPA Science Inventory

    The development of bioindicators for wetlands, especially ephemerally hydrated depressional and isolated wetlands, can be problematic because of seasonal changes in hydrology and target organism biology. To determine if benthic diatoms could be used as a year-round biological ind...

  3. Benthic diatom composition in isolated forested wetlands subject to drying: implications for monitoring and assessment

    EPA Science Inventory

    The development of bioindicators for wetlands, especially ephemerally hydrated depressional and isolated wetlands, can be problematic because of seasonal hydrology and target organism biology. To determine if benthic diatoms could be used as a year-round biological indicator of w...

  4. Coral reef condition and benthic sedimentation threat in four regions of south Puerto Rico

    EPA Science Inventory

    Scleractinian corals, gorgonian octocorals, sponges and fishes were assessed near the cities of LaParguera, Guánica, Guayanilla, and Jobos along the southern coast of Puerto Rico in November – December 2010. Survey sites were targeted near areas with varying benthic...

  5. Nearshore marine benthic invertebrates moving north along the U.S. Atlantic coast

    EPA Science Inventory

    Numerous species have shifted their ranges north in response to global warming. We examined 21 years (1990-2010) of marine benthic invertebrate data from the National Coastal Assessment’s monitoring of nearshore waters along the US Atlantic coast. Data came from three bioge...

  6. Streamflow characteristics and benthic invertebrate assemblages in streams across the western United States

    USGS Publications Warehouse

    Brasher, Anne M.D.; Konrad, Chris P.; May, Jason T.; Edmiston, C. Scott; Close, Rebecca N.

    2010-01-01

    Hydrographic characteristics of streamflow, such as high-flow pulses, base flow (background discharge between floods), extreme low flows, and floods, significantly influence aquatic organisms. Streamflow can be described in terms of magnitude, timing, duration, frequency, and variation (hydrologic regime). These characteristics have broad effects on ecosystem productivity, habitat structure, and ultimately on resident fish, invertebrate, and algae communities. Increasing human use of limited water resources has modified hydrologic regimes worldwide. Identifying the most ecologically significant hydrographic characteristics would facilitate the development of water-management strategies. Benthic invertebrates include insects, mollusks (snails and clams), worms, and crustaceans (shrimp) that live on the streambed. Invertebrates play an important role in the food web, consuming other invertebrates and algae and being consumed by fish and birds. Hydrologic alteration associated with land and water use can change the natural hydrologic regime and may affect benthic invertebrate assemblage composition and structure through changes in density of invertebrates or taxa richness (number of different species). This study examined associations between the hydrologic regime and characteristics of benthic invertebrate assemblages across the western United States and developed tools to identify streamflow characteristics that are likely to affect benthic invertebrate assemblages.

  7. Recent benthic foraminifera from the Caribbean continental slope and shelf off west of Colombia

    NASA Astrophysics Data System (ADS)

    Fiorini, Flavia

    2015-07-01

    A quantitative benthic foraminiferal analysis was conducted on 30 sea-floor sediment samples distributed along the continental slope and shelf in Fuerte Area (Colombian Caribbean), between 39 and 2469 m water depth. The aims of the research were to provide data on the distribution of southwestern Caribbean Recent benthic foraminifera, to estimate changes in the foraminiferal distribution related to the bathymetry and the characteristics of the substrate, to define a data-bank on distribution of recent tropical benthic foraminifera from the southwestern Caribbean, to provide reference on foraminiferal distribution that can be used in bathymetric reconstructions of ancient environments. Three different assemblages corresponding to three different environments were identified by cluster analysis. Assemblage A, characterized by variable percentages of porcellaneous, hyaline and agglutinated benthic foraminifera indicative of shelf environments. Assemblage B, dominated by calcareous hyaline foraminifera mainly composed of infaunal foraminifera corresponding to upper bathyal, marine conditions. Assemblage C, composed by agglutinated and calcareous hyaline foraminifera characteristic of normal deep-water marine environments.

  8. Nutrient enrichment homogenizes lake benthic assemblages at local and regional scales.

    PubMed

    Donohue, Ian; Jackson, Andrew L; Pusch, Martin T; Irvine, Kenneth

    2009-12-01

    The compositional heterogeneity of biotic assemblages among sites, or beta-diversity, regulates the relationship between local and regional species diversity across scales. Recent work has suggested that increased harshness of environmental conditions tends to reduce beta-diversity by decreasing the importance of stochastic processes in structuring assemblages. We investigated the effect of nutrient enrichment on the compositional heterogeneity of lake benthic invertebrate assemblages in Ireland at both local (within-lake) and regional (among-lake) scales. At local scales, we found that the compositional heterogeneity of benthic assemblages was related inversely to the extent of nutrient enrichment (as indicated by measurements of water column total phosphorus, total nitrogen, and chlorophyll a), after effects of lake morphology (i.e., surface area, connectivity, and depth of sampling) and alkalinity were accounted for. At regional scales, we found that nutrient-rich lakes had significantly more homogenous benthic assemblages than nutrient-poor lakes, over and above the effect of alkalinity and across a similar range of lake morphologies. These findings have profound implications for global aquatic biodiversity, as the homogenization of benthic assemblages at both local and regional scales may have important and unpredictable effects on whole aquatic ecosystems, with potentially considerable ecological and evolutionary consequences. PMID:20120814

  9. Intertidal Eelgrass Response to Benthic Macroalgal Accumulation in a Pacific Northwest Estuary

    EPA Science Inventory

    High accumulations of benthic macroalgae from excessive nutrient inputs to estuaries is commonly cited as a major cause of seagrass decline. Two measures of macroalgal abundance, biomass and percent cover, have been used in an assessment framework for estuarine condition propose...

  10. The Influence of Coral Reef Benthic Condition on Associated Fish Assemblages

    PubMed Central

    Chong-Seng, Karen M.; Mannering, Thomas D.; Pratchett, Morgan S.; Bellwood, David R.; Graham, Nicholas A. J.

    2012-01-01

    Accumulative disturbances can erode a coral reef’s resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs around the inner Seychelles islands. Specifically, relationships between benthic composition and the underlying substrata, as well as the associated fish assemblages were assessed. High variability in benthic composition was found among reefs, with a gradient from high coral cover (up to 58%) and high structural complexity to high macroalgae cover (up to 95%) and low structural complexity at the extremes. This gradient was associated with declining species richness of fishes, reduced diversity of fish functional groups, and lower abundance of corallivorous fishes. There were no reciprocal increases in herbivorous fish abundances, and relationships with other fish functional groups and total fish abundance were weak. Reefs grouping at the extremes of complex coral habitats or low-complexity macroalgal habitats displayed markedly different fish communities, with only two species of benthic invertebrate feeding fishes in greater abundance in the macroalgal habitat. These results have negative implications for the continuation of many coral reef ecosystem processes and services if more reefs shift to extreme degraded conditions dominated by macroalgae. PMID:22870294

  11. Bio-irrigation impacts on benthic-pelagic coupling in the Northern Adriatic

    NASA Astrophysics Data System (ADS)

    Capet, Arthur; Solidoro, Cosimo; De Vittor, Cinzia; Cibic, Tamara; Del Negro, Paola

    2016-04-01

    In the process of setting up a 3D benthic-pelagic coupled model for the northern Adriatic Sea, the 1D diagenetic OMEXDIA model was used to analyze pore-water profiles and in-situ flux data through model calibration. We tested two approach to represent bioirrigation in the model: the enhanced-biodiffusive formalism (initially used in OMEXDIA) and the non-local exchange formalism. Solutes profiles depicted shapes that could not be rendered by the biodiffusive formalism. Furthermore, calibration procedures stressed that only the non-local exchange formalism allows to render simultaneously the pore water solute profiles and the fluxes measured at the sediment water interface when carbon, oxygen, nitrogen and phosphate dynamics are considered jointly. While the enhanced-biodiffusive formalism is convenient in empirical studies comparing diffusive and total benthic fluxes for a single variable (derived from solutes profiles and incubation chambers respectively), it is not suited for multivariate modelling purposes. We evidence that the modeled impact of bioirrigation on benthic-pelagic coupling strongly differ following the adopted formalism, in particular in terms of the N:P ratio of remineralized fluxes. Calibrated parameters obtained for various stations are used to assess how bioirrigation impacts on benthic-pelagic coupling in the northern Adriatic.

  12. Proposed sediment quality criteria for the protection of benthic organisms: Dieldrin

    SciTech Connect

    Hansen, D.J.; Berry, W.J.; Di Toro, D.M.; Paquin, P.; Davanzo, L.

    1991-11-01

    The criteria presented in the document are the EPA's best recommendation of the concentrations of a substance in sediment that will not unacceptably affect benthic organisms. These criteria are applicable to a variety of freshwater and marine sediments because they are based on the biologically available concentration of dieldrin in sediments.

  13. Influence of stability and fragmentation of a worm-reef on benthic macrofauna

    NASA Astrophysics Data System (ADS)

    Godet, Laurent; Fournier, Jérôme; Jaffré, Mikaël; Desroy, Nicolas

    2011-05-01

    In coastal areas, reef-builder worms often are bio-engineers by structuring their physical and biological environment. Many studies showed that this engineering role is determined by the densities of the engineer species itself, the highest densities approximately corresponding to the most stable areas from a sedimentological point of view, and hosting the richest and the most diverse benthic fauna. Here, we tested the potential influence of the spatio-temporal dynamics and the spatial fragmentation of one of the largest European intertidal reefs generated by the marine worm Lanice conchilega (Pallas, 1766) (Annelida, Polychaeta) on the associated benthic macrofauna. We demonstrated that the worm densities do have a significant positive role on the abundance, biomass, species richness and species diversity of the benthic macrofauna and that the reef stability also significantly influences the biomass and species diversity. Moreover, the reef fragmentation has significant negative effects on the abundance, biomass and species richness. In addition to L. conchilega densities, the stability and the spatial fragmentation of the reef also significantly structure the associated benthic assemblages. This study demonstrates the interest of "benthoscape ecology" in understanding the role played by marine engineer species from a spatial point of view.

  14. BIOGEOGRAPHY OF BENTHIC MACROINVERTEBRATES IN ESTUARIES ALONG THE GULF OF MEXICO AND WESTERN ATLANTIC COASTS

    EPA Science Inventory

    The community composition of benthic macroinvertebrates from 870 estuarine sites was examimed in order to either confirm or challenge established boundaries of biogeographical provinces along the Gulf of Mexico and western Atlantic coasts of the United States. The objective was t...

  15. Benthic environments of the Lord Howe Rise submarine plateau: Introduction to the special volume

    NASA Astrophysics Data System (ADS)

    Harris, Peter T.

    2011-04-01

    The Australian exclusive economic zone (EEZ) contains1.6 million km 2 of submarine plateaus, equal to about 13.8% of the world's known inventory of these features. This disproportionate occurrence of plateaus presents Australia with an increased global responsibility to understand and protect the benthic habitats and associated ecosystems. This special volume presents the results of two major marine surveys carried out on the Lord Howe Rise plateau during 2003 and 2007, during which benthic biological and geological samples, underwater photographs, video and multibean sonar bathymetry data were collected. The benthic habitats present on Lord Howe Rise are dominated by slowly-accumulating, low-energy, soft-sediment habitats, but also include hard/rocky substrates covering a small area of volcanic peaks (around 31 km 2) and parts of other larger seamounts (e.g., the Lord Howe Island seamount) which support rich and abundant epifaunal assemblages dominated by suspension feeding invertebrates. These rocky habitats appear to qualify as ecologically and biologically significant areas under the United Nations Convention on Biological Diversity (CBD) scientific selection criteria 1 (uniqueness or rarity), 4 (vulnerability, fragility, sensitivity or slow recovery) and 7 (naturalness). The collection of papers included in this special volume represents a major advance in knowledge about benthic habitats of the Lord Howe Rise, but also about the ecology of submarine plateaus in general.

  16. High-throughput sequencing and morphology perform equally well for benthic monitoring of marine ecosystems.

    PubMed

    Lejzerowicz, Franck; Esling, Philippe; Pillet, Loïc; Wilding, Thomas A; Black, Kenneth D; Pawlowski, Jan

    2015-09-10

    Environmental diversity surveys are crucial for the bioassessment of anthropogenic impacts on marine ecosystems. Traditional benthic monitoring relying on morphotaxonomic inventories of macrofaunal communities is expensive, time-consuming and expertise-demanding. High-throughput sequencing of environmental DNA barcodes (metabarcoding) offers an alternative to describe biological communities. However, whether the metabarcoding approach meets the quality standards of benthic monitoring remains to be tested. Here, we compared morphological and eDNA/RNA-based inventories of metazoans from samples collected at 10 stations around a fish farm in Scotland, including near-cage and distant zones. For each of 5 replicate samples per station, we sequenced the V4 region of the 18S rRNA gene using the Illumina technology. After filtering, we obtained 841,766 metazoan sequences clustered in 163 Operational Taxonomic Units (OTUs). We assigned the OTUs by combining local BLAST searches with phylogenetic analyses. We calculated two commonly used indices: the Infaunal Trophic Index and the AZTI Marine Biotic Index. We found that the molecular data faithfully reflect the morphology-based indices and provides an equivalent assessment of the impact associated with fish farms activities. We advocate that future benthic monitoring should integrate metabarcoding as a rapid and accurate tool for the evaluation of the quality of marine benthic ecosystems.

  17. Relationships between stripmining-induced changes and benthic insect communities in the southern Appalachian Region

    SciTech Connect

    Tolbert, V. R.

    1980-01-01

    Increased demands for coal to supply America's energy needs, as well as the controversy surrounding the requirements and enforcement of the Surface Mining Control and Reclamation Act of 1977, point directly to the need for determination of specific factors associated with stripmining alteration that produce major environmental impacts. Numerous studies have demonstrated physical and chemical alterations to southern Appalachian streams subject to stripmining effluents found that the two major factors resulting in physical alterations were increased runoff and resultant sedimentation. Studies in streams receiving acid mine drainage showed that benthic insect communities differed in undisturbed and stripmining disturbed streams. Branson and Batch noted differences in benthic communities in Kentucky streams disturbed by non-acid stripmining. Tolbert found significant differences in benthic communities between undisturbed and nonacid mining streams. This paper describes research to determine what stripmining-altered parameters are responsible for differences in benthic insect communities. The results of this study can be applied toward validation of control measures required by the Surface Mining Control and Reclamation Act.

  18. Triclosan exposure increases triclosan resistance and influences taxonomic composition of benthic bacterial communities.

    PubMed

    Drury, Bradley; Scott, John; Rosi-Marshall, Emma J; Kelly, John J

    2013-08-01

    Triclosan (TCS) is a broad-spectrum antimicrobial compound that is incorporated into numerous consumer products. TCS has been detected in aquatic ecosystems across the U.S., raising concern about its potential ecological effects. We conducted a field survey and an artificial stream experiment to assess effects of TCS on benthic bacterial communities. Field sampling indicated that TCS concentrations in stream sediments increased with degree of urbanization. There was significant correlation between sediment TCS concentration and the proportion of cultivable benthic bacteria that were resistant to TCS, demonstrating that the levels of TCS present in these streams was affecting the native communities. An artificial stream experiment confirmed that TCS exposure could trigger increases in TCS resistance within cultivable benthic bacteria, and pyrosequencing analysis indicated that TCS resulted in decreased benthic bacterial diversity and shifts in bacterial community composition. One notable change was a 6-fold increase in the relative abundance of cyanobacterial sequences and a dramatic die-off of algae within the artificial streams. Selection of cyanobacteria over algae could have significant implications for higher trophic levels within streams. Finally, there were no observed effects of TCS on bacterial abundance or respiration rates, suggesting that bacterial density and function were highly resilient to TCS exposure.

  19. Application of Multiple Index Development Approaches to Benthic Invertebrate Data from the Virginian Biogeographic Province, USA

    EPA Science Inventory

    Previous work had indicated that the Virginian Province Index did not perform well in a smaller estuarine complex. While it was hoped that the existing Chesapeake Bay Benthic Index of Biotic Integrity, with its greater number of metrics and habitat separation would be more adapt...

  20. High-throughput sequencing and morphology perform equally well for benthic monitoring of marine ecosystems

    PubMed Central

    Lejzerowicz, Franck; Esling, Philippe; Pillet, Loïc; Wilding, Thomas A.; Black, Kenneth D.; Pawlowski, Jan

    2015-01-01

    Environmental diversity surveys are crucial for the bioassessment of anthropogenic impacts on marine ecosystems. Traditional benthic monitoring relying on morphotaxonomic inventories of macrofaunal communities is expensive, time-consuming and expertise-demanding. High-throughput sequencing of environmental DNA barcodes (metabarcoding) offers an alternative to describe biological communities. However, whether the metabarcoding approach meets the quality standards of benthic monitoring remains to be tested. Here, we compared morphological and eDNA/RNA-based inventories of metazoans from samples collected at 10 stations around a fish farm in Scotland, including near-cage and distant zones. For each of 5 replicate samples per station, we sequenced the V4 region of the 18S rRNA gene using the Illumina technology. After filtering, we obtained 841,766 metazoan sequences clustered in 163 Operational Taxonomic Units (OTUs). We assigned the OTUs by combining local BLAST searches with phylogenetic analyses. We calculated two commonly used indices: the Infaunal Trophic Index and the AZTI Marine Biotic Index. We found that the molecular data faithfully reflect the morphology-based indices and provides an equivalent assessment of the impact associated with fish farms activities. We advocate that future benthic monitoring should integrate metabarcoding as a rapid and accurate tool for the evaluation of the quality of marine benthic ecosystems. PMID:26355099

  1. Vertical distribution of benthic infauna in continental slope sediments off Cape Lookout, North Carolina

    NASA Astrophysics Data System (ADS)

    Blake, James A.

    The vertical distribution of 30 species of benthic infauna from continental slope (583-3000 m) sediments off Cape Lookout, North Carolina was closely correlated with feeding types. Carnivores, omnivores, filter feeders, and surface deposit feeders were mostly concentrated in the upper 0-2 cm of the cores. The depth distribution of subsurface deposit feeders was more variable, even among related taxa.

  2. EFFECTS OF HURRICANE KATRINA ON BENTHIC MACROINVERTEBRATE COMMUNITIES ALONG THE NORTHERN GULF OF MEXICO COAST

    EPA Science Inventory

    A study was initiated in fall 2005 to assess potential effects on benthic fauna and habitat quality in coastal waters of Louisiana, Mississippi, and Alabama following Hurricane Katrina, which struck the coast of Louisiana, between New Orleans and Bioloxi, Mississippi on August 29...

  3. Subtidal benthic macroinfaunal assemblages in tropical estuaries: generality amongst highly variable gradients.

    PubMed

    Barros, Francisco; de Carvalho, Gilson Correia; Costa, Yuri; Hatje, Vanessa

    2012-10-01

    South American estuaries are frequently not included in the search for general ecological models and studies dealing with biological assemblages in estuaries frequently do not sample the entire salinity gradient. We sampled three tropical estuaries, two times each, on ten stations distributed along each system. Six replicates were collected in each station for the benthic macroinfauna and sediment samples for grain size and inorganic contaminant analyses. There were finer sediments at the lower than at the upper estuarine portions. There was a decrease in the diversity, at family level, from marine to freshwater and the differences on the structure of the benthic assemblages were mostly spatial. In spite of the many different characteristics of the three estuaries (e.g. catchment size, pollution levels, proximity with the inner continental shelf) several consistent patterns of benthic macrofauna distribution along these systems were still observed. It suggested a general empirical model regarding the distribution of different benthic invertebrates along tropical salinity gradients which can be tested in different estuaries around the world.

  4. Application of a Eutrophic Condition Index to Benthic Macroalgal Accumulation in Pacific Northwest Estuaries

    EPA Science Inventory

    Studies of benthic macroalgal accumulation in coastal estuaries of the Pacific Northwest, USA, were conducted over a 12-year period, including aerial mapping and ground surveys. The results were applied to an assessment framework for eutrophication developed by the European Unio...

  5. Influence of item distribution pattern and abundance on efficiency of benthic core sampling

    USGS Publications Warehouse

    Behney, Adam C.; O'Shaughnessy, Ryan; Eichholz, Michael W.; Stafford, Joshua D.

    2014-01-01

    ore sampling is a commonly used method to estimate benthic item density, but little information exists about factors influencing the accuracy and time-efficiency of this method. We simulated core sampling in a Geographic Information System framework by generating points (benthic items) and polygons (core samplers) to assess how sample size (number of core samples), core sampler size (cm2), distribution of benthic items, and item density affected the bias and precision of estimates of density, the detection probability of items, and the time-costs. When items were distributed randomly versus clumped, bias decreased and precision increased with increasing sample size and increased slightly with increasing core sampler size. Bias and precision were only affected by benthic item density at very low values (500–1,000 items/m2). Detection probability (the probability of capturing ≥ 1 item in a core sample if it is available for sampling) was substantially greater when items were distributed randomly as opposed to clumped. Taking more small diameter core samples was always more time-efficient than taking fewer large diameter samples. We are unable to present a single, optimal sample size, but provide information for researchers and managers to derive optimal sample sizes dependent on their research goals and environmental conditions.

  6. Model of the Seasonal and Interannual Benthic Community Metabolism of the Northern Florida Reef Tract

    NASA Astrophysics Data System (ADS)

    Brock, J. C.; Yates, K. K.; Halley, R. B.; Nayegandhi, A.; Bracone, J.

    2006-12-01

    A model of the benthic carbon and carbonate metabolism across a 24 square kilometer region on the backreef platform of the northern Florida reef tract was used to estimate seasonal and interannual variability in excess production (E), respiration (R), and calcification (G) during 1995 through 2000. The topography and spatial benthic community structure of the reef zone segment investigated was mapped using the NASA Experimental Advanced Airborne Research Lidar (EAARL), combined with spectrally classified IKONOS satellite imagery. This 3-dimensional biotope structure was used to spatially scale community metabolism based on Submersible Habitat for the Assessment of Reef Quality (SHARQ) measurements of light-dependent net primary production, and background respiration and calcification rates. Hourly modeled clear sky surface irradiance corrected for cloudiness by observations from a nearby meteorological station was used to drive a non-spectral submarine light attenuation model. Benthic irradiance calculations were performed on a 1 meter grid, using hourly water column thickness fields derived from tide-corrected lidar bathymetry and interpolated archive ocean station observations of the diffuse attenuation coefficient. The resulting hourly 1 meter resolution bottom light fields were supplied to net community production versus irradiance functions based on SHARQ process measurements, and were extrapolated across the model domain using the IKONOS-derived 4 meter grid resolution substrate class map. Daily, monthly, and annual integrations of benthic community carbon and carbonate fluxes are reported by substrate type, depth interval, and for the entire reef zone segment investigated.

  7. Benthic invertebrate population characteristics as affected by water quality in coal-bearing regions of Tennessee

    SciTech Connect

    Bradfield, A.D.

    1986-01-01

    Linear regressions produced low correlation coefficients relating the number of taxa/sample, total number of organisms/sample, sample diversity, and percentage composition of selected orders of invertebrates, with average water quality parameter values available at sampling stations. Analyses of these data by linear regressions explained little of the variability in benthic invertebrate samples primarily because the distributions of benthic organisms along environmental gradients are nonlinear. Variability in substrate characteristics in the study area and seasonal insect emergence patterns also complicated interpretation of these data. However, analysis of variance tests did indicate significant trends towards reduced number of taxa, number of organisms, and sample diversity at stations with relatively poor water quality conditions. Decreasing percentage composition of Ephemeroptera was generally accompanied by an increase in percent Diptera at stations with higher water quality constituent concentrations and acidic pH. These trends indicate significant differences in benthic communities at sites with evidence of more severe land use impacts. Additional data on benthic invertebrates, water quality, and physical habitat conditions, along with analyses of data using multivariate statistical methods are needed to define ecological relations between specific groups of invertebrates and environmental conditions. 44 refs., 1 fig., 8 tabs.

  8. Benthic macroinvertebrates in lake ecological assessment: A review of methods, intercalibration and practical recommendations.

    PubMed

    Poikane, Sandra; Johnson, Richard K; Sandin, Leonard; Schartau, Ann Kristin; Solimini, Angelo G; Urbanič, Gorazd; Arbačiauskas, Kęstutis; Aroviita, Jukka; Gabriels, Wim; Miler, Oliver; Pusch, Martin T; Timm, Henn; Böhmer, Jürgen

    2016-02-01

    Legislation in Europe has been adopted to determine and improve the ecological integrity of inland and coastal waters. Assessment is based on four biotic groups, including benthic macroinvertebrate communities. For lakes, benthic invertebrates have been recognized as one of the most difficult organism groups to use in ecological assessment, and hitherto their use in ecological assessment has been limited. In this study, we review and intercalibrate 13 benthic invertebrate-based tools across Europe. These assessment tools address different human impacts: acidification (3 methods), eutrophication (3 methods), morphological alterations (2 methods), and a combination of the last two (5 methods). For intercalibration, the methods were grouped into four intercalibration groups, according to the habitat sampled and putative pressure. Boundaries of the 'good ecological status' were compared and harmonized using direct or indirect comparison approaches. To enable indirect comparison of the methods, three common pressure indices and two common biological multimetric indices were developed for larger geographical areas. Additionally, we identified the best-performing methods based on their responsiveness to different human impacts. Based on these experiences, we provide practical recommendations for the development and harmonization of benthic invertebrate assessment methods in lakes and similar habitats. PMID:26580734

  9. Development of Benthic Indicators for Nearshore Coastal Waters of New Jersey - A REMAP Project

    EPA Science Inventory

    EPA's National Coastal Assessment (NCA) is providing the first complete, consistent dataset on the condition of benthic communities in the nation's estuaries. Prior to NCA, New Jersey based its evaluation of the ecological condition of its coastal waters solely on dissolved oxyg...

  10. Marine benthic habitat mapping of the West Arm, Glacier Bay National Park and Preserve, Alaska

    USGS Publications Warehouse

    Hodson, Timothy O.; Cochrane, Guy R.; Powell, Ross D.

    2013-01-01

    Seafloor geology and potential benthic habitats were mapped in West Arm, Glacier Bay National Park and Preserve, Alaska, using multibeam sonar, groundtruthed observations, and geological interpretations. The West Arm of Glacier Bay is a recently deglaciated fjord system under the influence of glacial and paraglacial marine processes. High glacially derived sediment and meltwater fluxes, slope instabilities, and variable bathymetry result in a highly dynamic estuarine environment and benthic ecosystem. We characterize the fjord seafloor and potential benthic habitats using the recently developed Coastal and Marine Ecological Classification Standard (CMECS) by the National Oceanic and Atmospheric Administration (NOAA) and NatureServe. Due to the high flux of glacially sourced fines, mud is the dominant substrate within the West Arm. Water-column characteristics are addressed using a combination of CTD and circulation model results. We also present sediment accumulation data derived from differential bathymetry. These data show the West Arm is divided into two contrasting environments: a dynamic upper fjord and a relatively static lower fjord. The results of these analyses serve as a test of the CMECS classification scheme and as a baseline for ongoing and future mapping efforts and correlations between seafloor substrate, benthic habitats, and glacimarine processes.

  11. SPATIAL PATTERNS AND ECOLOGICAL DETERMINANTS OF BENTHIC ALGAL ASSEMBLAGES IN MID-ATLANTIC STREAMS, USA

    EPA Science Inventory

    We attempted to identify spatial patterns and determinants for benthic algal assemblages in Mid-Atlantic streams. Periphyton, water chemistry, stream physical habitat, riparian conditions, and land cover/use in watersheds were characterized at 89 randomly selected stream sites i...

  12. A response by benthic Foraminifera to the deposition of phytodetritus in the deep sea

    NASA Astrophysics Data System (ADS)

    Gooday, Andrew J.

    1988-03-01

    A recent major discovery has been the rapid sedimentation of phytodetritus to the deep-sea floor1-3 Although benthic mega-faunal invertebrates appear to seek out this relatively fresh food source1,4, and its seasonal arrival on the sea floor may synchronize reproduction in some echinoderms5, a convincing response by ben-thic organisms to phytodetritus has not been demonstrated3. Here I present evidence that certain small benthic Foraminifera (within the meiofaunal size-range) react dramatically to the presence of phytodetritus. Fresh aggregates of this material harbour abundant, low-diversity populations of these protists. The three commonest species are usually poorly represented in the more diverse assemblages inhabiting the underlying sediment. These findings suggest that some deep-sea benthic Foraminifera, like their shallow-water relatives6-8, are specialist feeders that bloom opportunistically when the appropriate food (phytodetritus and associated micro-organisms) becomes available, while others remain unaffected by the organic influx.

  13. BENTHIC AND WATER COLUMN PROCESSES IN A SUBTROPICAL ESTUARY: EFFECTS OF LIGHT ON OXYGEN FLUXES

    EPA Science Inventory

    Murrell, M.C., J.D. Hagy, J.G. Campbell and J.M. Caffrey. In press. Benthic and Water Column Processes in a Subtropical Estuary: Effects of Light on Oxygen Fluxes (Abstract). To be presented at the ASLO 2004 Summer Meeting: The Changing Landscapes of Oceans and Freshwater, 13-18 ...

  14. Macroecological drivers of archaea and bacteria in benthic deep-sea ecosystems.

    PubMed

    Danovaro, Roberto; Molari, Massimiliano; Corinaldesi, Cinzia; Dell'Anno, Antonio

    2016-04-01

    Bacteria and archaea dominate the biomass of benthic deep-sea ecosystems at all latitudes, playing a crucial role in global biogeochemical cycles, but their macroscale patterns and macroecological drivers are still largely unknown. We show the results of the most extensive field study conducted so far to investigate patterns and drivers of the distribution and structure of benthic prokaryote assemblages from 228 samples collected at latitudes comprising 34°N to 79°N, and from ca. 400- to 5570-m depth. We provide evidence that, in deep-sea ecosystems, benthic bacterial and archaeal abundances significantly increase from middle to high latitudes, with patterns more pronounced for archaea, and particularly for Marine Group I Thaumarchaeota. Our results also reveal that different microbial components show varying sensitivities to changes in temperature conditions and food supply. We conclude that climate change will primarily affect deep-sea benthic archaea, with important consequences on global biogeochemical cycles, particularly at high latitudes. PMID:27386507

  15. 2010 NCCA oligochaete trophic index results to inform benthic index development for the Great Lakes

    EPA Science Inventory

    Over 400 sites were sampled in the nearshore of the U.S. Great Lakes during the National Coastal Condition Assessment (NCCA) field survey in summer 2010. To assess benthic ecological condition, 393 PONARs were attempted, and collected macroinvertebrates were identified and enume...

  16. Effects of heavy metals on benthic macroinvertebrate communities in New Zealand streams

    SciTech Connect

    Hickey, C.W.; Clements, W.H.

    1998-11-01

    The authors performed chemical analyses of heavy metals in water and periphyton, toxicity tests with Daphnia magna and an indigenous mayfly (Deleatidium sp.), and field surveys of benthic macroinvertebrates to estimate the degree of metal pollution in three catchments in the Coromandel Peninsula of New Zealand. Good agreement was found between toxicity tests and measures of benthic community structure, particularly at stations with the highest metal levels. Responses of benthic communities at stations with low or moderate levels of metal contamination were variable and were probably confounded by factors other than heavy metals. Effects of heavy metals on benthic communities in New Zealand streams were similar to those reported for metal-polluted streams in North America and Europe, suggesting that responses to metal contamination are predictable. Abundance and species richness of mayflies, number of taxa in the orders Ephemeroptera, Plecoptera, and Trichoptera, and total taxonomic richness were the best indicators of heavy metals in New Zealand streams. In contrast, the quantitative macroinvertebrate community index (QMCI), a biotic index proposed for assessing effects of organic enrichment in New Zealand streams, could not distinguish between reference and metal-polluted streams. The poor performance of the QMCI was primarily due to incorrect tolerance scores for some taxa to heavy metals. Because of concerns regarding the subjective assignment of tolerance values to species, the authors recommend that tolerance values for dominant species in New Zealand streams should be verified experimentally in stream microcosms.

  17. Benthic macroinvertebrates in lake ecological assessment: A review of methods, intercalibration and practical recommendations.

    PubMed

    Poikane, Sandra; Johnson, Richard K; Sandin, Leonard; Schartau, Ann Kristin; Solimini, Angelo G; Urbanič, Gorazd; Arbačiauskas, Kęstutis; Aroviita, Jukka; Gabriels, Wim; Miler, Oliver; Pusch, Martin T; Timm, Henn; Böhmer, Jürgen

    2016-02-01

    Legislation in Europe has been adopted to determine and improve the ecological integrity of inland and coastal waters. Assessment is based on four biotic groups, including benthic macroinvertebrate communities. For lakes, benthic invertebrates have been recognized as one of the most difficult organism groups to use in ecological assessment, and hitherto their use in ecological assessment has been limited. In this study, we review and intercalibrate 13 benthic invertebrate-based tools across Europe. These assessment tools address different human impacts: acidification (3 methods), eutrophication (3 methods), morphological alterations (2 methods), and a combination of the last two (5 methods). For intercalibration, the methods were grouped into four intercalibration groups, according to the habitat sampled and putative pressure. Boundaries of the 'good ecological status' were compared and harmonized using direct or indirect comparison approaches. To enable indirect comparison of the methods, three common pressure indices and two common biological multimetric indices were developed for larger geographical areas. Additionally, we identified the best-performing methods based on their responsiveness to different human impacts. Based on these experiences, we provide practical recommendations for the development and harmonization of benthic invertebrate assessment methods in lakes and similar habitats.

  18. Structural responses of benthic macroinvertebrate communities from different stream orders to zinc

    SciTech Connect

    Kiffney, P.M.; Clements, W.H. . Dept. of Fishery and Wildlife Biology)

    1994-03-01

    It is well established that benthic invertebrate community structure and function shift in a predictable fashion along longitudinal stream gradients as a result of variation in environmental conditions. The authors research is concerned with experimentally testing whether this shift in community structure influences the response of benthic macroinvertebrates to heavy metals. Using artificial streams, they compared effects of Zn on natural assemblages of benthic macroinvertebrates communities collected from Little Beaver Creek (LBC; a third-order stream) and the Big South Fork of the Cache la Poudre, Colorado, catchment. Organisms collected from LBC and SFP were exposed to 0 or 130 [mu]g/L Zn in indoor experimental streams for 7 d. In general, similar taxa were found at both sites, but densities were generally higher at SFP than at LBC. They observed significant effects at the community and population level as a result of Zn, stream order, and the interaction between Zn and stream order. Specifically, mayflies from both sides were sensitive to Zn, but the magnitude of the response varied between sites. The results indicate that benthic macroinvertebrate communities from different stream order may vary in sensitivity to Zn.

  19. BENTHIC PRODUCTION AS THE BASE FOR FOOD WEBS IN ALASKAN ARCTIC LAKES

    EPA Science Inventory

    Plankton are traditionally viewed as the basis for limnetic food webs, with zooplankton acting as an energy gateway between phytoplanktonic primary producers and fish. Often, benthic production is considered to be important primarily to the benthos and in shallow systems, such as...

  20. BENTHIC MACROALGAE, DISSOLVED SULFIDES, AND AMPHIPODS IN SURFICIAL SEDIMENTS OF YAQUINA BAY ESTUARY, OREGON, USA

    EPA Science Inventory

    Surveys of benthic green macroalgae at two sites in Yaquina Bay Estuary, Oregon, in 1999 showed that percent cover and biomass values in June were much higher at one site, Idaho Point, than at the other site, Coquille Point. The frequency of detectable hydrogen sulfide odor late...

  1. TOXICITY OF CLAY FLOCCULATION OF RED TIDE ORGANISMS ON BENTHIC ORGANISMS ERF 2001

    EPA Science Inventory

    Toxicity of Clay Flocculation of Red Tide Organisms on Benthic Organisms (Abstract). To be presented at the16th Biennial Conference of the Estuarine Research Foundation, ERF 2001: An Estuarine Odyssey, 4-8 November 2001, St. Pete Beach, FL. 1 p. (ERL,GB R854).

    We have eva...

  2. A newly developed dispersal metric indicates the succession of benthic invertebrates in restored rivers.

    PubMed

    Li, Fengqing; Sundermann, Andrea; Stoll, Stefan; Haase, Peter

    2016-11-01

    Dispersal capacity plays a fundamental role in the riverine benthic invertebrate colonization of new habitats that emerges following flash floods or restoration. However, an appropriate measure of dispersal capacity for benthic invertebrates is still lacking. The dispersal of benthic invertebrates occurs mainly during the aquatic (larval) and aerial (adult) life stages, and the dispersal of each stage can be further subdivided into active and passive modes. Based on these four possible dispersal modes, we first developed a metric (which is very similar to the well-known and widely used saprobic index) to estimate the dispersal capacity for 802 benthic invertebrate taxa by incorporating a weight for each mode. Second, we tested this metric using benthic invertebrate community data from a) 23 large restored river sites with substantial improvements of river bottom habitats dating back 1 to 10years, b) 23 unrestored sites very close to the restored sites, and c) 298 adjacent surrounding sites (mean±standard deviation: 13.0±9.5 per site) within a distance of up to 5km for each restored site in the low mountain and lowland areas of Germany. We hypothesize that our metric will reflect the temporal succession process of benthic invertebrate communities colonizing the restored sites, whereas no temporal changes are expected in the unrestored and surrounding sites. By applying our metric to these three river treatment categories, we found that the average dispersal capacity of benthic invertebrate communities in the restored sites significantly decreased in the early years following restoration, whereas there were no changes in either the unrestored or the surrounding sites. After all taxa had been divided into quartiles representing weak to strong dispersers, this pattern became even more obvious; strong dispersers colonized the restored sites during the first year after restoration and then significantly decreased over time, whereas weak dispersers continued to increase

  3. A newly developed dispersal metric indicates the succession of benthic invertebrates in restored rivers.

    PubMed

    Li, Fengqing; Sundermann, Andrea; Stoll, Stefan; Haase, Peter

    2016-11-01

    Dispersal capacity plays a fundamental role in the riverine benthic invertebrate colonization of new habitats that emerges following flash floods or restoration. However, an appropriate measure of dispersal capacity for benthic invertebrates is still lacking. The dispersal of benthic invertebrates occurs mainly during the aquatic (larval) and aerial (adult) life stages, and the dispersal of each stage can be further subdivided into active and passive modes. Based on these four possible dispersal modes, we first developed a metric (which is very similar to the well-known and widely used saprobic index) to estimate the dispersal capacity for 802 benthic invertebrate taxa by incorporating a weight for each mode. Second, we tested this metric using benthic invertebrate community data from a) 23 large restored river sites with substantial improvements of river bottom habitats dating back 1 to 10years, b) 23 unrestored sites very close to the restored sites, and c) 298 adjacent surrounding sites (mean±standard deviation: 13.0±9.5 per site) within a distance of up to 5km for each restored site in the low mountain and lowland areas of Germany. We hypothesize that our metric will reflect the temporal succession process of benthic invertebrate communities colonizing the restored sites, whereas no temporal changes are expected in the unrestored and surrounding sites. By applying our metric to these three river treatment categories, we found that the average dispersal capacity of benthic invertebrate communities in the restored sites significantly decreased in the early years following restoration, whereas there were no changes in either the unrestored or the surrounding sites. After all taxa had been divided into quartiles representing weak to strong dispersers, this pattern became even more obvious; strong dispersers colonized the restored sites during the first year after restoration and then significantly decreased over time, whereas weak dispersers continued to increase

  4. Comparison of Adjective vs. Benthic Sources of Nutrients to a Former Salt Pond under Restoration

    NASA Astrophysics Data System (ADS)

    Topping, B.; Kuwabara, J. S.; Garrett, K.; Takekawa, J.; Piotter, S.; Parchaso, F.

    2013-12-01

    With the implementation of the South Bay Restoration Program in 2008, water quality in the Alviso Salt Ponds, California, has been monitored to document the effects of changing hydrologic connections among the ponds and the adjacent pond, slough and estuary. In 2010 and 2012, pore-water profilers (U.S. Patent 8,051,727 B1) were deployed in Pond A3W, a former salt pond just north of Moffett Federal Airfield that mixes hydrologically through culverts and weirs with Guadalupe Slough and neighboring ponds, to assess the magnitude of diffusive benthic flux, generated primarily by remobilization of surface-reactive solutes in bed sediment accumulated over annual to decadal time scales. The study, focusing on macronutrient sources that may stimulate harmful algal blooms, revealed that orthophosphate, ammonia, and silica benthic flux were consistently positive (out of the sediment) in both 2010 and 2012, while nitrate and nitrite fluxes were negligible. Because tidal height can affect the size and direction of flow, a diurnal study of nutrient advective flux into and out of the pond was measured during neap and spring tides. These advective fluxes (kg/yr) were compared to benthic flux estimates for the pond extrapolated over the 2.27 (km2) pond surface. Benthic flux of inorganic nitrogen species, averaged over all sites and dates, was about 80,000 + 48,000 kilograms per year (kg/yr), well above the adjective flux range of -50 to 1,500 kg/yr. By contrast, the average benthic flux of orthophosphate was about 12,000 + 4,400 kg/yr, well below the advective flux range of 21,500 to 30,000 kg/yr. Benthic flux estimates determined by porewater gradients do not include enhancement processes such as bioturbation, bioirrigation, wind resuspension, and potential groundwater inflows. However, they provide a conservative measure and can be an effective management screening tool. These results indicate that benthic transport may be an important source of biologically reactive solutes for

  5. Structures of benthic prokaryotic communities and their hydrolytic enzyme activities resuspended from samples of intertidal mudflats: An experimental approach

    NASA Astrophysics Data System (ADS)

    Mallet, Clarisse; Agogué, Hélène; Bonnemoy, Frédérique; Guizien, Katell; Orvain, Francis; Dupuy, Christine

    2014-09-01

    Resuspended sediment can increase plankton biomass and the growth of bacteria, thus influencing the coastal planktonic microbial food web. But little is known about resuspension itself: is it a single massive change or a whole series of events and how does it affect the quantity and quality of resuspended prokaryotic cells? We simulated the sequential erosion of mud cores to better understand the fate and role of benthic prokaryotes resuspended in the water column. We analyzed the total, attached and free-living prokaryotic cells resuspended, their structure and the activities of their hydrolytic enzymes in terms of the biotic and abiotic factors that affect the composition of microphytobenthic biofilm. Free living prokaryotes were resuspended during the fluff layer erosion phase (for shear velocities below 5 cm · s- 1) regardless of the bed sediment composition. At the higher shear velocities, resuspended prokaryotes were attached to particulate matter. Free and attached cells are thus unevenly distributed, scattered throughout the organic matter (OM) in the uppermost mm of the sediment. Only 10-27% of the total cells initially resuspended were living and most of the Bacteria were Cyanobacteria and Gamma-proteobacteria; their numbers increased to over 30% in parallel with the hydrolytic enzyme activity at highest shear velocity. These conditions released prokaryotic cells having different functions that lie deep in the sediment; the most important of them are Archaea. Finally, composition of resuspended bacterial populations varied with resuspension intensity, and intense resuspension events boosted the microbial dynamics and enzyme activities in the bottom layers of sea water.

  6. Experimental evidence of biomineralisation for three benthic foraminiferal species under different redox conditions: implications for paleo-redox proxies interpretation

    NASA Astrophysics Data System (ADS)

    Nardelli, Maria Pia; Barras, Christine; Metzger, Edouard; Filipsson, Helena; Jorissen, Frans; Geslin, Emmanuelle

    2014-05-01

    Foraminifera are among the most used group of organisms for paleoceanographic and paleoenvironmental reconstructions thanks to their ability to fossilize and the preservation potential in marine sediments. Calibrations of foraminiferal-based proxies are therefore of crucial importance for precise reconstructions together with uncertainty estimates of paleoenvironments; experimental approaches are increasingly used to deepen the understanding of biological and ecological aspects of biomineralization that can influence shell geochemistry. Some of the most important and still unanswered questions are: under which circumstances can foraminiferal biomineralization take place? Can their shells record different oxygenation levels and redox fronts migrations at the sediment-water interface? The hypothesis of their ability to biomineralise even in absence of oxygen was investigated in an experimental study. Calcein-labeled specimens of three benthic foraminiferal species, Ammonia tepida, Bulimina marginata and Cassidulina laevigata were introduced in different sediment layers of reconstituted cores (up to 10 cm depth). The sediment layers were separated by 100 µm mesh-size nets preventing specimen migrations. We could therefore evaluate the ability of the species to calcify at different redox fronts in the sediment. The results show that all species were able to calcify within 2 months in hypoxic. Two of them (Ammonia tepida and Bulimina marginata) are also able to calcify in completely anoxic conditions. The result suggests that foraminifera could register in their calcareous shells the migration of redox fronts associated to bottom-water oxygen depletions and anoxic events. With the help of microanalytical tools it will potentially be possible to reconstruct past oxygen levels with much higher accuracy and precision and to obtain proxies of completely anoxic conditions.

  7. Effects of Benthic Flux on Dissolved-Mercury Distributions in Camp Far West Reservoir, California

    NASA Astrophysics Data System (ADS)

    Kuwabara, J. S.; Alpers, C. N.; Marvin-Dipasquale, M.; Topping, B. R.; Carter, J. L.; Stewart, A. R.; Fend, S. V.; Parchaso, F.; Moon, G. E.; Krabbenhoft, D. P.; Agee, J. L.; Kieu, L. H.

    2003-12-01

    Benthic flux measurements of dissolved mercury species were made on sediment cores from Camp Far West Reservoir, a reservoir in which elevated mercury levels in sport fish had previously been documented. The reservoir is located downstream of historic hydraulic placer-gold mining and ore processing activities in the Bear River watershed of the northern Sierra Nevada. Field and laboratory studies were conducted in April and November of 2002 (one of the driest years on record for the area) to provide the first direct measurements of the benthic flux of dissolved mercury species between bottom sediment and the water column at three locations within the reservoir. Ancillary data, including nutrient and ligand fluxes, and benthic biological characterizations, were also gathered to provide a water-quality framework with which to interpret the mercury results. The following are the major observations made from interdependent physical, biological, and chemical data. Bottom water total mercury (HgT) concentrations ranged from 2.94 to 18.3 pM. Dissolved HgT benthic fluxes were generally higher in April than in November 2002 (based on site averages from replicate cores). HgT fluxes of 36.3 and -28.4 pmoles-m-2-h-1 were measured in cores from the deep site which was suboxic in November, contrasting with positive fluxes of 306 and 272 pmoles-m-2-h-1 at that site in April 2002 when the bottom water was oxic. All six measurements of HgT flux in April 2002 and five of six in November 2002 resulted in positive values (i.e., out of the sediment into the overlying water column). Consistent with benthic fluxes for HgT, dissolved MeHg fluxes were: (a) generally positive in April 2002, (b) negligible at all sites in November 2002, and (c) at least two orders of magnitude lower than total-mercury fluxes, roughly consistent with concentration differences between species. Observed concentration ranges for MeHg in bottom water ranged from less than the detection limit (0.20 pM) at the two

  8. Role of macrofauna on benthic oxygen consumption in sandy sediments of a high-energy tidal beach

    NASA Astrophysics Data System (ADS)

    Charbonnier, Céline; Lavesque, Nicolas; Anschutz, Pierre; Bachelet, Guy; Lecroart, Pascal

    2016-06-01

    Sandy beaches exposed to tide and waves are characterized by low abundance and diversity of benthic macrofauna, because of high-energy conditions. This is the reason why there are few studies on benthic communities living in such highly dynamic environments. It has been shown recently that tidal sandy beaches may act as biogeochemical reactors. Marine organic matter that is supplied in the sand during each flood tide is efficiently mineralized through aerobic respiration. In order to quantify the role of macrofauna in the whole beach benthic respiration, we studied the macrofauna and the pore water oxygen content of an exposed sandy beach (Truc Vert, SW of France) during four seasons in 2011. The results showed that macrofauna was characterised by a low number of species of specialized organisms such as the crustaceans Eurydice naylori and Gastrosaccus spp. and the polychaetes Ophelia bicornis and Scolelepis squamata. The distribution and abundance of macrofauna were clearly affected by exposure degree and emersion time. The combined monitoring of benthic macrofauna and pore waters chemistry allowed us to estimate (1) the macrofauna oxygen uptake, calculated with a standard allometric relationship using biomass data, and (2) the total benthic oxygen uptake, calculated from the oxygen deficit measured in pore waters. This revealed that benthic macrofauna respiration represented a variable but low (<10%) contribution to the total benthic oxygen consumption. This suggests that oxygen was mainly consumed by microbial respiration.

  9. Food sources of benthic animals on intertidal and subtidal bottoms in inner Ariake Sound, southern Japan, determined by stable isotopes

    NASA Astrophysics Data System (ADS)

    Yokoyama, Hisashi; Sakami, Tomoko; Ishihi, Yuka

    2009-04-01

    To evaluate the relative importance of possible food sources, including riverine particulate organic matter, reeds, benthic microalgae, seaweeds, cultured laver ( Porphyra) and coastal phytoplankton, for commercial bivalves and co-occurring benthic animals, 73 macrofaunal species were collected from intertidal and subtidal soft bottoms in the inner part of Ariake Sound, Kyushu, southern Japan, and their isotopic compositions were analyzed. The results revealed that (1) both intertidal and subtidal food webs were constituted of 3 trophic levels, (2) suspension-feeding bivalves utilize a mixture of benthic microalgae and coastal phytoplankton, and omnivores and carnivores incorporate benthic microalgae and phytoplankton through their intermediate prey, and (3) 3 bivalves ( Scapharca kagoshimensis, Modiolus metcalfei and Atrina lischkeana) inhabiting both intertidal and subtidal bottoms showed similar seasonal fluctuations, suggesting no difference in the diet composition among the species and between the 2 habitats. We conclude that a large biomass of benthic microalgae which was approximately equal to that of phytoplankton and the strong tidal currents that would resuspend benthic microalgae and transport them to subtidal bottom areas account for the benthic microalgal and phytoplankton based trophic structure in the inner part of Ariake Sound.

  10. Importance of benthic production to fish populations in Lake Mead prior to the establishment of quagga mussels

    USGS Publications Warehouse

    Umek, John; Chandra, Sudeep; Rosen, Michael; Wittmann, Marion; Sullivan, Joe; Orsak, Erik

    2010-01-01

    Limnologists recently have developed an interest in quantifying benthic resource contributions to higher-level consumers. Much of this research focuses on natural lakes with very little research in reservoirs. In this study, we provide a contemporary snapshot of the food web structure of Lake Mead to evaluate the contribution of benthic resources to fish consumers. In addition, we document the available food to fishes on soft sediments and changes to the invertebrate community over 2 time periods. Benthic invertebrate food availability for fishes is greater in Las Vegas Bay than Overton Arm. Las Vegas Bay is dominated by oligochaetes, whose biomass increased with depth, while Overton Arm is dominated by chironomids, whose biomass did not change with depth. Diet and isotopic measurements indicate the fish community largely relies on benthic resources regardless of basin (Las Vegas Bay >80%; Overton Arm >92%); however, the threadfin shad likely contribute more to largemouth and striped bass production in Overton Arm versus Las Vegas Bay. A 2-time period analysis, pre and post quagga mussel establishment and during lake level declines, suggests there is no change in the density of benthic invertebrates in Boulder Basin, but there were greater abundances of select taxa in this basin by season and depth than in other basins. Given the potential of alterations as a result of the expansion of quagga mussel and the reliance of the fishery on benthic resources, future investigation of basin specific, benthic processes is recommended.

  11. Toxicity of human pharmaceuticals and personal care products to benthic invertebrates.

    PubMed

    Dussault, Eve B; Balakrishnan, Vimal K; Sverko, Ed; Solomon, Keith R; Sibley, Paul K

    2008-02-01

    Despite concerns about potential risks associated with the presence of pharmaceuticals and personal care products (PPCPs) in the environment, few toxicological data address the effects of these compounds. In aquatic systems, which often represent the final repository for PPCPs, increasing toxicological information regarding aquatic biota is improving our capacity to assess potential risks. However, responses of key biota, such as benthic invertebrates, have not been investigated as widely. In the present study, we examined the toxicity of four PPCPs -- the lipid regulator atorvastatin (ATO), the antiepileptic drug carbamazepine (CBZ), the synthetic hormone 17alpha-ethinylestradiol (EE(2)), and the antimicrobial triclosan (TCS) -- to the midge Chironomus tentans and the freshwater amphipod Hyalella azteca in 10-d waterborne exposures. The toxicity of the four compounds varied between 0.20 and 47.3 mg/L (median lethal concentration), with a relative toxicity ranking of TCS > EE(2) > ATO > CBZ. Hyalella azteca was more sensitive than C. tentans to these compounds. The toxicity data were used in a hazard quotient approach to evaluate the risk posed by the four PPCPs to benthic invertebrates and other aquatic organisms. For each compound, a hazard quotient was calculated by dividing the lowest toxicity value by the highest exposure value found in the literature, to which an uncertainty factor was applied. With hazard quotients of 3.55 to 11.5, we conclude that potential risks exist toward benthic invertebrates for the toxicity of TCS and CBZ and that further investigations of these compounds are required to characterize more completely the risks to benthic organisms. In contrast, our data also indicate that considering the low concentrations currently detected in the environment, ATO and EE(2) pose negligible risks to benthic invertebrates.

  12. Pleistocene oceanographie changes indicated by deep sea benthic foraminifera in the northern Indian Ocean

    NASA Astrophysics Data System (ADS)

    Rai, Ajai K.; Srinivasan, M. S.

    1994-12-01

    An attempt has been made to understand the Pleistocene bottom water history in response to the paleoclimatic changes in the northern Indian Ocean employing quantitative analyses of deep sea benthic foraminifera at the DSDP sites 219 and 238. Among the 150 benthic foraminifera recorded a few species show dominance with changing percent frequencies during most of the sequence. The dominant benthic foraminiferal assemblages suggest that most of the Pleistocene bottom waters at site 219 and Early Pleistocene bottom waters at site 238 are of North Indian Deep Water (NIDW) origin. However, Late Pleistocene assemblage at site 238 appears to be closely associated with a water mass intermediate between North Indian Deep Water (NIDW) and Antarctic Bottom Water (AABW). Uvigerina proboscidea is the most dominant benthic foraminiferal species present during the Pleistocene at both the sites. A marked increase in the relative abundance of U. proboscidea along with less diverse and equitable fauna during Early Pleistocene suggests a relative cooling, an intensified oceanic circulation and upwelling of nutrient rich bottom waters resulting in high surface productivity. At the same time, low sediment accumulation rate during Early Pleistocene reveals increased winnowing of the sediments possibly due to more corrosive and cold bottom waters. The Late Pleistocene in general, is marked by relatively warm and stable bottom waters as reflected by low abundance of U. proboscidea and more diverse and equitable benthic fauna. The lower depth range for the occurrence of Bulimina aculeate in the Indian Ocean is around 2300 m, similar to that of many other areas. B. aculeata also shows marked increase in its abundance near the Pliocene/Pleistocene boundary while a sudden decrease in the relative abundance of Stilostomella lepidula occurs close to the Early/Late Pleistocene boundary.

  13. Effects of heavy metals pollution on benthic foraminifera assemblage: the Gulf of Gabes, Tunisia

    NASA Astrophysics Data System (ADS)

    Ayadi, Najla; Zghal, Ihsen; Bouzid, Jalel; Abdennaceur Ouali, Jamel

    2014-05-01

    Benthic foraminifera are amongst the most abundant protists found in huge marine and brackish water habitat. During the last few decades, many researches had been focused on using benthic foraminifera as bioindicators of marine pollution caused by industrial, domestic and agricultural waste, oil or heavy metal contamination. The aim of this research is to investigate heavy metals pollution in superficial sediments in two industrial locations at the Gulf of Gabes and to examine the reaction of benthic foraminifera towards metallic concentration. The Gulf of Gabes, located on the eastern coast of Tunisia, is regarded as an extremely vital zone and considered as one of the most important area for fishing in the country. During last years, the coastal area of this region had known an important demographic and industrial development, leading to the presence of uncontrolled discharge. Fifteen superficial sediment samples were collected along the coastline of Skhira and Ghannouch- Gabes. They have been analyzed for Al, Cd, Cr, Cu, Pb, and Zn concentrations as well as for the species composition of benthic foraminifera. Results show three levels of metallic contamination with high concentration of cadmium and zinc. Thirty five benthic foraminifera species were identified. Ammonia parkinsoniana, Ammonia beccarii, Peneroplis planatus, Triloculina trigonula and Adelosina longirostraare are the most abundant and common species. Increasing pollution results in a lower species diversity as well as population density, with the presence of a barren zone, and more frequent abnormal specimens. A complementary statistical analysis (PCA/FA and matrix correlation) shows that heavy metals are resulting from the same anthropogenic source and negative correlation between faunal parameters (density and diversity) and pollutants concentrations.

  14. Differential bioaccumulation of potentially toxic elements in benthic and pelagic food chains in Lake Baikal.

    PubMed

    Ciesielski, Tomasz M; Pastukhov, Mikhail V; Leeves, Sara A; Farkas, Julia; Lierhagen, Syverin; Poletaeva, Vera I; Jenssen, Bjørn M

    2016-08-01

    Lake Baikal is located in eastern Siberia in the center of a vast mountain region. Even though the lake is regarded as a unique and pristine ecosystem, there are existing sources of anthropogenic pollution to the lake. In this study, the concentrations of the potentially toxic trace elements As, Cd, Pb, Hg, and Se were analyzed in water, plankton, invertebrates, and fish from riverine and pelagic influenced sites in Lake Baikal. Concentrations of Cd, Hg, Pb and Se in Lake Baikal water and biota were low, while concentrations of As were similar or slightly higher compared to in other freshwater ecosystems. The bioaccumulation potential of the trace elements in both the pelagic and the benthic ecosystems differed between the Selenga Shallows (riverine influence) and the Listvenichnyĭ Bay (pelagic influence). Despite the one order of magnitude higher water concentrations of Pb in the Selenga Shallows, Pb concentrations were significantly higher in both pelagic and benthic fish from the Listvenichnyĭ Bay. A similar trend was observed for Cd, Hg, and Se. The identified enhanced bioavailability of contaminants in the pelagic influenced Listvenichnyĭ Bay may be attributed to a lower abundance of natural ligands for contaminant complexation. Hg was found to biomagnify in both benthic and pelagic Baikal food chains, while As, Cd, and Pb were biodiluted. At both locations, Hg concentrations were around seven times higher in benthic than in pelagic fish, while pelagic fish had two times higher As concentrations compared to benthic fish. The calculated Se/Hg molar ratios revealed that, even though Lake Baikal is located in a Se-deficient region, Se is still present in excess over Hg and therefore the probability of Hg induced toxicity in the endemic fish species of Lake Baikal is assumed to be low. PMID:27130338

  15. Biotic disturbance and benthic community dynamics in salmon-bearing streams.

    PubMed

    Moore, Jonathan W; Schindler, Daniel E

    2008-03-01

    1. Organisms can impact ecosystems via multiple pathways, often with positive and negative impacts on inhabitants. Understanding the context dependency of these types of impacts remains challenging. For example, organisms may perform different functions at different densities. 2. Anadromous salmon accumulate > 99% of their lifetime growth in marine ecosystems, and then return to spawn, often at high densities, in relatively confined freshwaters. While previous research has focused on how salmon nutrients can fertilize benthic communities, we examined how an ecosystem engineer, sockeye salmon Oncorhynchus nerka, influences seasonal dynamics of stream benthic communities through their nest-digging activities in south-western Alaska, USA. Benthic invertebrate and algal abundance were quantified every 7-14 days during the open water seasons of 10 streams in riffle and run habitats across multiple years, leading to 25 different stream-year combinations that spanned a large gradient of salmon density. 3. In streams with few or no salmon, benthic algal and insect biomass were fairly constant throughout the season. However, in streams with more than 0.1 salmon m(-2), algal and insect biomass decreased by an average of 75-85% during salmon spawning. Algal biomass recovered quickly following salmon disturbance, occasionally reaching pre-salmon biomass. In contrast, in streams with more than 0.1 salmon m(-2), aquatic insect populations did not recover to pre-salmon levels within the same season. We observed no positive impacts of salmon on algae or insects via fertilization from carcass nutrients. 4. Salmon, when their populations exceed thresholds in spawning density, are an important component of stream disturbance regimes and influence seasonal dynamics of benthic communities. Human activities that drive salmon densities below threshold densities, as has likely happened in many streams, will lead to altered seasonal dynamics of stream communities. Human activities that

  16. Oxygenation episodes on the continental shelf of central Peru: Remote forcing and benthic ecosystem response

    NASA Astrophysics Data System (ADS)

    Gutiérrez, Dimitri; Enríquez, E.; Purca, S.; Quipúzcoa, L.; Marquina, R.; Flores, G.; Graco, M.

    2008-10-01

    The interplay between the oxygen minimum zone and remotely-forced oxygenation episodes determines the fate of the benthic subsystem off the Central Peruvian coast. We analyzed a 12 year monthly time-series of oceanographic and benthic parameters at 94 m depth off Callao, Central Peru (12°S), to analyze: (i) near-bottom oxygen level on the continental shelf in relation to dynamic height on the equator (095°W); and (ii) benthic ecosystem responses to oxygen change (macrobiotic infauna, meiofauna, and sulphide-oxidizing bacteria, Thioploca spp.). Shelf oxygenation episodes occurred after equatorial dynamic height increases one month before, consistent with the propagation of coastal trapped waves. Several but not all of these episodes occurred during El Niños. The benthic biota responded to oxygenation episodes by undergoing succession through three major ecological states. Under strong oxygen deficiency or anoxia, the sediments were nearly defaunated of macro-invertebrates and Thioploca was scarce, such that nematode biomass dominated the macro- and meiobiotas. When frequency of oxygenation events reduced the periods of anoxia, but the prevailing oxygen range was 10-20 μmol L -1, mats of Thioploca formed and dominated the biomass. Finally, with frequent and intense (>40 μmol L -1) oxygenation, the sediments were colonized by macrofauna, which then dominated biomass. The Thioploca state evolved during the 2002-2003 weak EN, while the macrofauna state was developed during the onset of the strong1997-1998 EN. Repeated episodes of strong oxygen deficiency during the summer of 2004, in parallel with the occurrence of red tides in surface waters, resulted in the collapse of Thioploca mats and development of the Nematode state. Ecological interactions may affect persistence or the transition between benthic ecosystem states.

  17. Benthic-pelagic coupling: effects on nematode communities along southern European continental margins.

    PubMed

    Pape, Ellen; Jones, Daniel O B; Manini, Elena; Bezerra, Tania Nara; Vanreusel, Ann

    2013-01-01

    Along a west-to-east axis spanning the Galicia Bank region (Iberian margin) and the Mediterranean basin, a reduction in surface primary productivity and in seafloor flux of particulate organic carbon was mirrored in the in situ organic matter quantity and quality within the underlying deep-sea sediments at different water depths (1200, 1900 and 3000 m). Nematode standing stock (abundance and biomass) and genus and trophic composition were investigated to evaluate downward benthic-pelagic coupling. The longitudinal decline in seafloor particulate organic carbon flux was reflected by a reduction in benthic phytopigment concentrations and nematode standing stock. An exception was the station sampled at the Galicia Bank seamount, where despite the maximal particulate organic carbon flux estimate, we observed reduced pigment levels and nematode standing stock. The strong hydrodynamic forcing at this station was believed to be the main cause of the local decoupling between pelagic and benthic processes. Besides a longitudinal cline in nematode standing stock, we noticed a west-to-east gradient in nematode genus and feeding type composition (owing to an increasing importance of predatory/scavenging nematodes with longitude) governed by potential proxies for food availability (percentage of nitrogen, organic carbon, and total organic matter). Within-station variability in generic composition was elevated in sediments with lower phytopigment concentrations. Standing stock appeared to be regulated by sedimentation rates and benthic environmental variables, whereas genus composition covaried only with benthic environmental variables. The coupling between deep-sea nematode assemblages and surface water processes evidenced in the present study suggests that it is likely that climate change will affect the composition and function of deep-sea nematodes.

  18. Biogeography of Planktonic and Benthic Archaeal Communities in a Subtropical Eutrophic Estuary of China.

    PubMed

    Hu, Anyi; Hou, Liyuan; Yu, Chang-Ping

    2015-08-01

    Mounting evidence suggests that Archaea are widespread and abundant in aquatic and terrestrial habitats and play fundamental roles in global biogeochemical cycles, yet the pattern and its ecological drivers of biogeographic distribution of archaeal community in estuarine ecosystem are still not well understood. Here, we investigated planktonic and benthic archaeal communities in the human-impacted Jiulong River estuary (JRE), southern China by using real-time PCR (RT-PCR) and Illumina 16S ribosomal RNA (rRNA) amplicon sequencing. RT-PCR analysis indicated that Archaea accounted for an average of 0.79 and 5.31 % of prokaryotic biomass in water and sediment samples of the JRE, respectively. The diversity of planktonic archaeal community decreased gradually from the river runoff to seawater, whereas that of benthic community did not show the similar pattern. The results of taxonomic assignments indicated that Thaumarchaeota (Nitrosopumilus and Cenarchaeum), Methanocorpusculum, and Methanospirillum were significantly more abundant in planktonic than benthic communities, whereas the relative abundances of Miscellaneous Crenarchaeotic Group, Marine Benthic Group-B/-D, anaerobic methane-oxidizing Archaea -1/-2D, and South Africa Gold Mine Euryarchaeotic Group 1 were higher in sediments than in surface waters. Moreover, planktonic archaeal community composition varied significantly at broad and finer-scale taxonomic levels along the salinity gradient. Multivariate statistical analyses revealed that salinity is the main factor structuring the JRE planktonic but not benthic archaeal community at both total community and population level. SourceTrakcer analysis indicated that river might be a major source of archaea in the freshwater zone of the JRE. Overall, this study advances our understanding of the biogeographic patterns and its ecological drivers of estuarine archaeal communities.

  19. Implications of Colorado river (Texas, USA) freshwater inflow to benthic ecosystem dynamics: A modeling study

    NASA Astrophysics Data System (ADS)

    Kim, Hae-Cheol; Montagna, Paul A.

    2009-08-01

    Estuaries are defined by mixing of freshwater from rivers and saltwater from seas. Water resource development can reduce river flows to the coast, but it is difficult to predict effects on estuaries. The Lavaca-Colorado Estuary is a major estuarine system along the Texas coast that provides major economic benefit to the region by supporting a variety of agricultural, residential, industrial, and recreational functions. New water projects could divert freshwater from Matagorda Bay. So, what environmental effects could result from further changes to inflow patterns in the Matagorda Bay system? To answer this question, a bioenergetic model, calibrated using a long-term dataset of benthic biomass, was run to investigate dynamics of macrobenthic biomass related to salinity regimes in the estuary. The model simulation results were interpreted to assess the role of freshwater inflow in controlling benthic productivity. Simulations, based on calibrated parameters (1988-1999), were run for a long-term period from 1988 to 2005. The model performance was found to be promising with the best percent root mean square (RMS) difference being 63% and worst being 92%. Sensitivity tests for the benthic responses to changes in salinity show that, in general, when salinity increased with decreasing nutrient concentrations, deposit feeder biomass increased while suspension feeder biomass decreased. Estuary-wide comparison predicts that reducing freshwater inflow may cause the upper and lower bay communities to respond in different ways. Reduced inflow to Lavaca Bay would result in decreasing benthic biomass; whereas, in Matagorda Bay, biomass would increase. Also, functional diversity would decrease in both bays with decreasing inflow. These effects are probably due to the benthic community acclimating to different salinity regimes, or more (or less) salt tolerant species populating the area. It is concluded that freshwater inflow plays an important role in maintaining the observed

  20. Mg isotope fractionation in biogenic carbonates of deep-sea coral, benthic foraminifera, and hermatypic coral.

    PubMed

    Yoshimura, Toshihiro; Tanimizu, Masaharu; Inoue, Mayuri; Suzuki, Atsushi; Iwasaki, Nozomu; Kawahata, Hodaka

    2011-11-01

    High-precision Mg isotope measurements by multiple collector inductively coupled plasma mass spectrometry were applied for determinations of magnesium isotopic fractionation of biogenic calcium carbonates from seawater with a rapid Mg purification technique. The mean δ(26)Mg values of scleractinian corals, giant clam, benthic foraminifera, and calcite deep-sea corals were -0.87‰, -2.57‰, -2.34‰, and -2.43‰, suggesting preferential precipitation of light Mg isotopes to produce carbonate skeleton in biomineralization. Mg isotope fractionation in deep-sea coral, which has high Mg calcite skeleton, showed a clear temperature (T) dependence from 2.5 °C to 19.5 °C: 1,000 × ln(α) = -2.63 (±0.076) + 0.0138 (±0.0051) × T(R(2) = 0.82, p < 0.01). The δ(26)Mg values of large benthic foraminifera, which are also composed of a high-Mg calcite skeleton, can be plotted on the same regression line as that for deep-sea coral. Since the precipitation rates of deep-sea coral and benthic foraminifera are several orders of magnitude different, the results suggest that kinetic isotope fractionation may not be a major controlling factor for high-Mg calcite. The Mg isotope fractionation factors and the slope of temperature dependence from deep-sea corals and benthic foraminifera are similar to that for an inorganically precipitated calcite speleothem. Taking into account element partitioning and the calcification rate of biogenic CaCO(3), the similarity among inorganic minerals, deep-sea corals, and benthic foraminiferas may indicate a strong mineralogical control on Mg isotope fractionation for high-Mg calcite. On the other hand, δ(26)Mg in hermatypic corals composed of aragonite has been comparable with previous data on biogenic aragonite of coral, sclerosponges, and scaphopad, regardless of species differences of samples.

  1. Zebra mussels affect benthic predator foraging success and habitat choice on soft sediments.

    PubMed

    Beekey, M A; McCabe, D J; Marsden, J E

    2004-09-01

    The introduction of zebra mussels ( Dreissena spp.) to North America has resulted in dramatic changes to the complexity of benthic habitats. Changes in habitat complexity may have profound effects on predator-prey interactions in aquatic communities. Increased habitat complexity may affect prey and predator dynamics by reducing encounter rates and foraging success. Zebra mussels form thick contiguous colonies on both hard and soft substrates. While the colonization of substrata by zebra mussels has generally resulted in an increase in both the abundance and diversity of benthic invertebrate communities, it is not well known how these changes affect the foraging efficiencies of predators that prey on benthic invertebrates. We examined the effect of zebra mussels on the foraging success of four benthic predators with diverse prey-detection modalities that commonly forage in soft substrates: slimy sculpin ( Cottus cognatus), brown bullhead ( Ameirus nebulosus), log perch ( Percina caprodes), and crayfish ( Orconectes propinquus). We conducted laboratory experiments to assess the impact of zebra mussels on the foraging success of predators using a variety of prey species. We also examined habitat use by each predator over different time periods. Zebra mussel colonization of soft sediments significantly reduced the foraging efficiencies of all predators. However, the effect was dependent upon prey type. All four predators spent more time in zebra mussel habitat than in either gravel or bare sand. The overall effect of zebra mussels on benthic-feeding fishes is likely to involve a trade-off between the advantages of increased density of some prey types balanced against the reduction in foraging success resulting from potential refugia offered in the complex habitat created by zebra mussels.

  2. The Role of Benthic Currents and Sediment Transport On Deep-water Coral Mound Morphology and Growth: Examples From The Belgica and Moira Mounds, Eastern Porcupine Seabight, NE Atlantic

    NASA Astrophysics Data System (ADS)

    Wheeler, A.; Kozachenko, M.; Olu-Le Roy, K.

    tive features on the seafloor. In doing so, corals become elevated above the benthic- boundary layers gaining access to fast flowing waters (with increased nutrient flux) with a lower sediment yield thus stimulating further biological growth, sand entrap- ment and increases in mound elevation. 2

  3. Food web flows through a sub-arctic deep-sea benthic community

    NASA Astrophysics Data System (ADS)

    Gontikaki, E.; van Oevelen, D.; Soetaert, K.; Witte, U.

    2011-11-01

    The benthic food web of the deep Faroe-Shetland Channel (FSC) was modelled by using the linear inverse modelling methodology. The reconstruction of carbon pathways by inverse analysis was based on benthic oxygen uptake rates, biomass data and transfer of labile carbon through the food web as revealed by a pulse-chase experiment. Carbon deposition was estimated at 2.2 mmol C m -2 d -1. Approximately 69% of the deposited carbon was respired by the benthic community with bacteria being responsible for 70% of the total respiration. The major fraction of the labile detritus flux was recycled within the microbial loop leaving merely 2% of the deposited labile phytodetritus available for metazoan consumption. Bacteria assimilated carbon at high efficiency (0.55) but only 24% of bacterial production was grazed by metazoans; the remaining returned to the dissolved organic matter pool due to viral lysis. Refractory detritus was the basal food resource for nematodes covering ∼99% of their carbon requirements. On the contrary, macrofauna seemed to obtain the major part of their metabolic needs from bacteria (49% of macrofaunal consumption). Labile detritus transfer was well-constrained, based on the data from the pulse-chase experiment, but appeared to be of limited importance to the diet of the examined benthic organisms (<1% and 5% of carbon requirements of nematodes and macrofauna respectively). Predation on nematodes was generally low with the exception of sub-surface deposit-feeding polychaetes that obtained 35% of their energy requirements from nematode ingestion. Carnivorous polychaetes also covered 35% of their carbon demand through predation although the preferred prey, in this case, was other macrofaunal animals rather than nematodes. Bacteria and detritus contributed 53% and 12% to the total carbon ingestion of carnivorous polychaetes suggesting a high degree of omnivory among higher consumers in the FSC benthic food web. Overall, this study provided a unique

  4. Benthic-Pelagic Coupling in Biogeochemical and Climate Models: Existing Approaches, Recent developments and Roadblocks

    NASA Astrophysics Data System (ADS)

    Arndt, Sandra

    2016-04-01

    Marine sediments are key components in the Earth System. They host the largest carbon reservoir on Earth, provide the only long term sink for atmospheric CO2, recycle nutrients and represent the most important climate archive. Biogeochemical processes in marine sediments are thus essential for our understanding of the global biogeochemical cycles and climate. They are first and foremost, donor controlled and, thus, driven by the rain of particulate material from the euphotic zone and influenced by the overlying bottom water. Geochemical species may undergo several recycling loops (e.g. authigenic mineral precipitation/dissolution) before they are either buried or diffuse back to the water column. The tightly coupled and complex pelagic and benthic process interplay thus delays recycling flux, significantly modifies the depositional signal and controls the long-term removal of carbon from the ocean-atmosphere system. Despite the importance of this mutual interaction, coupled regional/global biogeochemical models and (paleo)climate models, which are designed to assess and quantify the transformations and fluxes of carbon and nutrients and evaluate their response to past and future perturbations of the climate system either completely neglect marine sediments or incorporate a highly simplified representation of benthic processes. On the other end of the spectrum, coupled, multi-component state-of-the-art early diagenetic models have been successfully developed and applied over the past decades to reproduce observations and quantify sediment-water exchange fluxes, but cannot easily be coupled to pelagic models. The primary constraint here is the high computation cost of simulating all of the essential redox and equilibrium reactions within marine sediments that control carbon burial and benthic recycling fluxes: a barrier that is easily exacerbated if a variety of benthic environments are to be spatially resolved. This presentation provides an integrative overview of

  5. Multiscale patterns in the diversity and organization of benthic intertidal fauna among French Atlantic estuaries

    NASA Astrophysics Data System (ADS)

    Blanchet, Hugues; Gouillieux, Benoît; Alizier, Sandrine; Amouroux, Jean-Michel; Bachelet, Guy; Barillé, Anne-Laure; Dauvin, Jean-Claude; de Montaudouin, Xavier; Derolez, Valérie; Desroy, Nicolas; Grall, Jacques; Grémare, Antoine; Hacquebart, Pascal; Jourde, Jérôme; Labrune, Céline; Lavesque, Nicolas; Meirland, Alain; Nebout, Thiebaut; Olivier, Frédéric; Pelaprat, Corine; Ruellet, Thierry; Sauriau, Pierre-Guy; Thorin, Sébastien

    2014-07-01

    Based on a parallel sampling conducted during autumn 2008, a comparative study of the intertidal benthic macrofauna among 10 estuarine systems located along the Channel and Atlantic coasts of France was performed in order to assess the level of fauna similarity among these sites and to identify possible environmental factors involved in the observed pattern at both large (among sites) and smaller (benthic assemblages) scales. More precisely this study focused on unraveling the observed pattern of intertidal benthic fauna composition and diversity observed at among-site scale by exploring both biotic and abiotic factors acting at the among- and within-site scales. Results showed a limited level of similarity at the among-site level in terms of intertidal benthic fauna composition and diversity. The observed pattern did not fit with existing transitional water classification methods based on fish or benthic assemblages developed in the frame of the European Water Framework Directive (WFD). More particularly, the coastal plain estuaries displayed higher among-site similarity compared to ria systems. These coastal plain estuaries were characterized by higher influence of river discharge, lower communication with the ocean and high suspended particulate matter levels. On the other hand, the ria-type systems were more dissimilar and different from the coastal plain estuaries. The level of similarity among estuaries was mainly linked to the relative extent of the intertidal “Scrobicularia plana-Cerastoderma edule” and “Tellina tenuis” or “Venus” communities as a possible consequence of salinity regime, suspended matter concentrations and fine particles supply with consequences on the trophic functioning, structure and organization of benthic fauna. Despite biogeographical patterns, the results also suggest that, in the context of the WFD, these estuaries should only be compared on the basis of the most common intertidal habitat occurring throughout all

  6. Overview of the chemical ecology of benthic marine invertebrates along the western Antarctic peninsula.

    PubMed

    McClintock, James B; Amsler, Charles D; Baker, Bill J

    2010-12-01

    Thirteen years ago in a review that appeared in the American Zoologist, we presented the first survey of the chemical and ecological bioactivity of Antarctic shallow-water marine invertebrates. In essence, we reported that despite theoretical predictions to the contrary the incidence of chemical defenses among sessile and sluggish Antarctic marine invertebrates was widespread. Since that time we and others have significantly expanded upon the base of knowledge of Antarctic marine invertebrates' chemical ecology, both from the perspective of examining marine invertebrates in new, distinct geographic provinces, as well as broadening the evaluation of the ecological significance of secondary metabolites. Importantly, many of these studies have been framed within established theoretical constructs, particularly the Optimal Defense Theory. In the present article, we review the current knowledge of chemical ecology of benthic marine invertebrates comprising communities along the Western Antarctic Peninsula (WAP), a region of Antarctica that is both physically and biologically distinct from the rest of the continent. Our overview indicates that, similar to other regions of Antarctica, anti-predator chemical defenses are widespread among species occurring along the WAP. In some groups, such as the sponges, the incidence of chemical defenses against predation is comparable to, or even slightly higher than, that found in tropical marine systems. While there is substantial knowledge of the chemical defenses of benthic marine invertebrates against predators, much less is known about chemical anti-foulants. The sole survey conducted to date suggests that secondary metabolites in benthic sponges are likely to be important in the prevention of fouling by benthic diatoms, yet generally lack activity against marine bacteria. Our understanding of the sensory ecology of Antarctic benthic marine invertebrates, despite its great potential, remains in its infancy. For example, along the

  7. Benthic foraminiferal response to the emergence of the Isthmus of Panama and coincident paleoceanographic changes

    USGS Publications Warehouse

    McDougall, K.

    1996-01-01

    Late Cenozoic benthic foraminiferal faunas from the Caribbean Deep Sea Drilling Project (DSDP) Site 502 (3052 m) and East Pacific DSDP Site 503 (3572 m) were analyzed to interpret bottom-water masses and paleoceanographic changes occurring as the Isthmus of Panama emerged. Major changes during the past 7 Myr occur at 6.7-6.2, 3.4, 2.0, and 1.1 Ma in the Caribbean and 6.7-6.4, 4.0-3.2, 2.1, 1.4, and 0.7 Ma in the Pacific. Prior to 6.7 Ma, benthic foraminiferal faunas at both sites indicate the presence of Antarctic Bottom Water (AABW). After 6.7 Ma benthic foraminiferal faunas indicate a shift to warmer water masses: North Atlantic Deep Water (NADW) in the Caribbean and Pacific Deep Water (PDW) in the Pacific. Flow of NADW may have continued across the rising sill between the Caribbean and Pacific until 5.6 Ma when the Pacific benthic foraminiferal faunas suggest a decrease in bottom-water temperatures. After 5.6 Ma deep-water to intermediate-water flow across the sill appears to have stopped as the bottom-water masses on either side of the sill diverge. The second change recorded by benthic foraminiferal faunas occurs at 3.4 Ma in the Caribbean and 4.0-3.2 Ma in the Pacific. At this time the Caribbean is flooded with cold AABW, which is either gradually warmed or is replaced by Glacial Bottom Water (GBW) at 2.0 Ma and by NADW at 1.1 Ma. These changes are related to global climatic events and to the depth of the sill between the Caribbean and Atlantic rather than the rising Isthmus of Panama. Benthic foraminiferal faunas at East Pacific Site 503 indicate a gradual change from cold PDW to warmer PDW between 4.0 and 3.2 Ma. The PDW is replaced by the warmer, poorly oxygenated PIW at 2.1 Ma. Although the PDW affects the faunas during colder intervals between 1.4 and 0.7 Ma, the PIW remains the principal bottom- water mass in the Guatemala Basin of the East Pacific.

  8. Comparison of marine productivity among Outer Continental Shelf planning areas. Supplement: An evaluation of benthic habitat primary productivity. Final report

    SciTech Connect

    Balcom, B.J.; Foster, M.A.; Fourqurean, J.J.; Heine, J.N.; Leonard, G.H.

    1991-01-01

    Literature on current primary productivity was reviewed and evaluated for each of nine benthic communities or habitats, estimates of daily and annual benthic primary productivity were derived within each community, the benthic primary estimates were related to an estimate of areal extent of each community within or adjacent to each OCS planning area. Direct comparisons between habitats was difficult because of the varying measures and methodologies used. Coastal marshes were the most prevalent habitat type evaluated. Mangrove and coral reef habitats were highly productive but occur within few planning areas. Benthic diatoms and blue-green algae are less productive in terms of estimated annual productivity on a per square meter basis; these habitats have the potential to occur across wide areas of the OCS and should not be overlooked.

  9. Estimating benthic secondary production from aquatic insect emergence in streams affected by mountaintop removal coal mining, West Virginia USA

    EPA Science Inventory

    Mountaintop removal and valley fill (MTR/VF) coal mining recountours the Appalachian landscape, buries headwater stream channels, and degrades downstream water quality. The goal of this study was to compare benthic community production estimates, based on seasonal insect emergen...

  10. Assessing the benthic ecological status in the stressed coastal waters of Yantai, Yellow Sea, using AMBI and M-AMBI.

    PubMed

    Li, Baoquan; Wang, Quanchao; Li, Bingjun

    2013-10-15

    The coastal waters around Yantai have been subjected to a variety of anthropogenic pressures over the last two decades. To assess the current benthic ecological health and the recovery process of the benthic ecosystem, four surveys were conducted in 2010 and 2011. The AMBI and M-AMBI were applied to assess the benthic ecological status. The ecological status of the Sishili Bay and Taozi Bay was "moderate" to "good" at most sampling stations during four surveys, but some stations were degraded due to pollution and eutrophication induced by human activities. The ecological status improved after removal of the marine raft culture and minimizing the amount of waste water discharged into the coastal waters of Yantai. The AMBI and M-AMBI could be used as suitable bio-indicator indices to assess the benthic ecological status of coastal waters in Yantai, Shandong Province.

  11. IMPORTANCE OF MATERNAL TRANSFER OF THE PHOTOREACTIVE POLYCYCLIC AROMATIC HYDROCARBON FLUORANTHENE FROM BENTHIC ADULT BIVALVES TO THEIR PELAGIC LARVAE

    EPA Science Inventory

    Laboratory experiments were conducted to determine if maternal transfer of polycyclic aromatic hydrocarbons (PAHs) from benthic adult bivalves could result in phototoxicity to their pelagic larvae when exposed to ultraviolet light (UV). In these experiments, adult bivalves were e...

  12. Relationships among levels of benthic vegetation and pore-water sulfides, burrowing shrimp and infaunal amphipods in Yaquina estuary, Oregon

    EPA Science Inventory

    Benthic amphipods are an important component of estuarine food webs, which in turn support ecological services provided by near shore commercial and recreational fisheries. In this study relationships among biological and geochemical aspects of the intertidal community were inve...

  13. DEVELOPMENT OF A STREAM BENTHIC MACROINVERTEBRATE INTEGRITY INDEX (SBMII) FOR WADEABLE STREAMS IN THE MID-ATLANTIC HIGHLANDS REGION

    EPA Science Inventory

    The Stream Benthic Macroinvertebrate Integrity Index (SBMII), a multimetric biotic index for assessing biological conditions of wadeable streams, was developed using seven macroinvertebrate metrics (Ephemeroptera richness, Plecoptera richness, Trichoptera richness, Collector-Filt...

  14. History of benthic research in the English Channel: From general patterns of communities to habitat mosaic description

    NASA Astrophysics Data System (ADS)

    Dauvin, Jean-Claude

    2015-06-01

    Benthic studies in the English Channel (EC), a shallow megatidal and epicontinental sea, began in the 1960s and 1970s with the work of teams led by Norman Holme (UK) and Louis Cabioch (F). During this period, benthic sampling was mainly qualitative, i.e. using a device such as the 'Rallier du Baty' dredge in the case of the French team and a modified anchor dredge in the case of the British team. Studies were focused on acquiring knowledge of the main distributions of benthic communities and species. Surveys on the scale of the whole EC led to the recognition of general features and two main patterns were identified: 1) the role of hydrodynamics on the spatial distribution of sediment, benthic species and communities; 2) the presence of a west-east climatic gradient of faunal impoverishment. Benthic studies in the 1980s-1990s were focused on the beginning of the implementation of long-term survey at a limited number of sites to identify seasonal and multi-annual changes. In the first decade of the 2000s, the implementation of the European Water Framework Directive and the Marine Strategy Framework Directive to define the Ecological Quality Status of marine environments increased the need to acquire better information of the structure and functioning of benthic communities, since benthic species and habitats were recognised as good indicators of human pressure on marine ecosystems. Faced with the increase of human maritime activities, the appearance of invasive species and the need to preserve sensitive marine habitats, benthic studies have been focused on developing a 'toolkit' to help in the decision-making and planning for both sound governance and sustainable management of marine resources and