Sample records for benthic nepheloid layer

  1. Response of the benthic nepheloid layer to near-inertial internal waves in southern Lake Michigan

    E-print Network

    Response of the benthic nepheloid layer to near-inertial internal waves in southern Lake Michigan-inertial internal waves are correlated with variations in the thickness and in the vertical distribution of suspended sediment in the benthic nepheloid layer. Although a direct causal link between internal wave

  2. Suspended sediment transport in the benthic nepheloid layer in southeastern Lake Michigan

    SciTech Connect

    Hawley, N. [Great Lakes Environmental Research Lab., Ann Arbor, MI (United States); Lesht, B.M. [Argonne National Lab., IL (United States)

    1995-02-01

    Time series observations of water temperature, water transparency, and current velocity were made at four stations located on the lake slope of southeastern Lake Michigan. The observations show that during stratified conditions the benthic nepheloid layer is probably not maintained by the local resuspension of bottom sediment. A more likely source is sediment resuspended further inshore and then transported across the shelf and slope during downwelling events. Internal wave action may be an important source of energy for this transport. Although sediment trap studies suggest that resuspension does occur, it is more likely that increased fluxes observed near the bottom are due to the vertical redistribution of material already in suspension. A benthic nepheloid layer also exists at times during the unstratified period, when occassionally enough energy reaches the bottom to directly resuspend bottom material at the sites.

  3. 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.

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

    PubMed

    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 10(5) 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 10(15) cysts, whereas the BNL inventory in the Bay of Fundy is on the order of 10(16) . 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

  5. Optics, Acoustics, and Stress in a Nearshore Bottom Nepheloid Layer Emmanuel Boss

    E-print Network

    Boss, Emmanuel S.

    Optics, Acoustics, and Stress in a Nearshore Bottom Nepheloid Layer Emmanuel Boss School of Marine stresses and how this packaging of sediment affects optical and acoustical properties in the water column and acoustical properties of the water column. 3. Develop models describing the associations between particle

  6. Optics, Acoustics, and Stress in a Nearshore Bottom Nepheloid Layer Emmanuel Boss

    E-print Network

    Boss, Emmanuel S.

    Optics, Acoustics, and Stress in a Nearshore Bottom Nepheloid Layer Emmanuel Boss School of Marine this packaging of sediment affects optical and acoustical properties in the water column. OBJECTIVES 1. Quantify. Quantify how changes in particle packaging affect the optical and acoustical properties of the water column

  7. 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.

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

    Microsoft Academic Search

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

    2010-01-01

    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

  9. 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 basins west of the Mid-Atlantic Ridge, resulting from interaction of abyssal currents with the bottom, range from ??? 2 ?? 106 tons in the equatorial Guyana Basin to ??? 50 ?? 106 tons in the North American Basin. The total resuspended particulate load in the western basins (111 ?? 106 tons) is almost an order of magnitude greater than that in the basins east of the Mid-Atlantic Ridge (13 ?? 106 tons). The net northward flux of resuspended particles carried in the AABW drops from ??? 8 ?? 106 tons/year between the southern and northern ends of the Brazil Basin and remains ??? 1 ?? 106 tons/year across the Guyana Basin. ?? 1977.

  10. Vertical structure and biological activity in the bottom nepheloid layer of the Gulf of Maine

    NASA Astrophysics Data System (ADS)

    Townsend, D. W.; Mayer, L. M.; Dortch, Q.; Spinrad, R. W.

    1992-02-01

    The bottom nepheloid layer (BNL) was investigated at a number of hydrographically different sites in the Gulf of Maine during August 1987. Observations were based on hydrographic measurements made from a surface ship and closely-spaced, near-bottom samples collected using a submersible. The BNL generally occurred as a turbid layer which extended 15-30 m above the bottom (m.a.b.), as indicated by in situ light transmission and increased concentrations of total suspended particulate matter (SPM). Phytoplankton pigments, electron transport activity (ETS), extracellular proteolytic enzyme activity (EPA), concentrations of particulate organic carbon and nitrogen (POC and PON), and protein were generally elevated in the BNL. They also displayed vertical distribution patterns in relation to near-bottom depth zones of increased abundances of zooplankton, bacteria and autotrophic and heterotrophic nanoplankton. We describe two zones of biological significance in the BNL. The first, at about 20 m.a.b. at most stations, was associated with greater zooplankton biomass (80 ?m) and copepod abundances than those depth strata either above or below, and appeared to be related to a higher quality of food particles near the top of the BNL. A second zone was seen 1-3 m.a.b. at most stations in association with the greatest levels of SPM. This deeper zone was generally of a poorer food quality, as reflected by ratios of protein-N to total-N and showed increases in cell-specific EPA. We discuss the areal variability of the BNL in the Gulf of Maine as well as the biological enhancement and vertical structure as likely influenced by both physical and biological processes.

  11. 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 levels were enriched in compounds yielding acetonitrile upon pyrolysis, i.e. nitrogen-containing compounds. If the proximity of the river source and regime influenced the suspended particulate matter distribution and the geochemical characteristics of organic matter, the evolution through time of the bottom turbid flow from one station to another also had a great influence. Near the bottom, the terrestrial character is shown in the shoreward stations by high contents of pyrolysis-derived aromatic hydrocarbons and phenols as well as by lignin-derived phenolic compounds analysed by HPLC. In contrast, a marine character appeared in the seaward stations, emphasized by high values of pyrolysis-derived compounds indicative of carbohydrates and nitrogenous compounds as well as by phenolic compounds representative of phytoplankton production. However the upper water layers of the bottom nepheloid were generally more influenced by terrestrial input. Some trends emphasizing a microstratification of the water layers in the deeper levels of the bottom nepheloid, related to the existence of very thin bottom currents, or, maybe, to resuspension processes resulting from the bottom proximity, were shown by the geochemical characteristics of the three water levels analysed.

  12. Some hydrodynamic problems for a nepheloid zone

    Microsoft Academic Search

    Takashi Ichiye

    1966-01-01

    A layer of a few hundred meters thickness with suspended matter (a nepheloid zone) was discovered byEwing andThorndike [4]3) near the bottom on the continental slope of the North Atlantic. A downward pressure gradient is produced in this layer due to increment of water density with suspensoid. When only the Coriolis force balances with this pressure gradient, a bottom nepheloid

  13. Effect of benthic boundary layer transport on the productivity of Mono Lake, California

    PubMed Central

    Bruce, Louise C; Jellison, Robert; Imberger, Jörg; Melack, John M

    2008-01-01

    The significance of the transport of nutrient-rich hypolimnetic water via the benthic boundary layer (BBL) to the productivity of Mono Lake was studied using a coupled hydrodynamic and ecological model validated against field data. The coupled model enabled us to differentiate between the role of biotic components and hydrodynamic forcing on the internal recycling of nutrients necessary to sustain primary productivity. A 4-year period (1991–1994) was simulated in which recycled nutrients from zooplankton excretion and bacterially-mediated mineralization exceeded sediment fluxes as the dominant source for primary productivity. Model outputs indicated that BBL transport was responsible for a 53% increase in the flux of hypolimnetic ammonium to the photic zone during stratification with an increase in primary production of 6% and secondary production of 5%. Although the estimated impact of BBL transport on the productivity of Mono Lake was not large, significant nutrient fluxes were simulated during periods when BBL transport was most active. PMID:18710583

  14. Redox-sensitive element uptake in north-east Atlantic Ocean sediments (Benthic Boundary Layer Experiment sites)

    Microsoft Academic Search

    J. Thomson; S. Nixon; I. W. Croudace; T. F. Pedersen; L. Brown; G. T. Cook; A. B. MacKenzie

    2001-01-01

    Regularly increasing radiocarbon age–depth profiles and near-constant sediment composition with depth have demonstrated that sediment accumulation has been relatively constant during the late Holocene at two north-east Atlantic sites on Rockall Bank and Feni Drift (UK Benthic Boundary Layer Experiment sites). In such a quasi-steady state situation, the geochemical responses to early diagenesis of the redox-sensitive elements Cd, Mn, Mo,

  15. Sediment trap fluxes and benthic recycling of organic carbon, polycyclic aromatic hydrocarbons, and polychlorobiphenyl congeners in Lake Superior

    SciTech Connect

    Baker, J.E.; Eisenreich, S.J. (Univ. of Minnesota, Minneapolis (USA)); Eadie, B.J. (NOAA, Ann Arbor, MI (USA))

    1991-03-01

    Sediment trap fluxes of solids, organic carbon, polycyclic aromatic hydrocarbons (PAHs), and polychlorinated biphenyls (PCBs) were measured in Lake Superior in 1984 and 1985. Mass fluxes from surface waters ranged from 0.14 to 1.1 g/m{sup 2}{center dot}day and increased near the lake floor due to resuspension of surficial sediment and horizontal transport in the benthic nepheloid layer. Organic matter fluxes from surface water ranged from 60 to 90 mg of C/m{sup 2}{center dot}day, with {approximately}5% of organic carbon settling from surface waters accumulating in bottom sediments. Concentrations of PCBs and PAHs are enriched 10-100 times on settling particles relative to those on suspended particles. Resultant settling fluxes are 10-100 times greater for several PCB and PAH compounds than net accumulation rates in bottom sediments, indicating the effective and rapid recycling in the benthic region. Biological packaging of organic pollutants into rapidly settling particles is an efficient pathway for the transport of contaminants from surface waters to benthic regions of large lakes.

  16. Transport and transformation of dissolved and particulate materials on continental margins influenced by major rivers: benthic boundary layer and seabed processes

    Microsoft Academic Search

    B. A. McKee; R. C. Aller; M. A. Allison; T. S. Bianchi; G. C. Kineke

    2004-01-01

    Within the benthic boundary layer (BBL) and seabed of river-dominated ocean margins (RiOMars), the timing, kinetics and extent of important biogeochemical processes are greatly influenced by large riverine inputs of dissolved and particulate terrestrial materials. An examination of our current state of knowledge reveals that the rates of primary productivity, sediment deposition, remineralization and burial in these margins are among

  17. Dynamics of the benthic boundary layer and seafloor contributions to oxygen depletion on the Oregon inner shelf

    NASA Astrophysics Data System (ADS)

    McCann-Grosvenor, Kristina; Reimers, Clare E.; Sanders, Rhea D.

    2014-08-01

    Measurement of in situ O2 consumption and production within permeable sediments, such as those found over the Oregon-Washington inner shelf, has traditionally been done using methods that isolate the sediments from the dynamic influences of currents and wave motions. Modified from atmospheric research, the non-invasive eddy correlation technique can be used to characterize benthic boundary layer dynamics and measure O2 flux across the sediment-water interface without excluding the natural hydrodynamic flow. In 2009, eddy correlation measurements were made in 5 discrete months with varying conditions at a 30 m site off Yaquina Head, Newport, OR. The O2 flux was found to be primarily into the bed (-18±3 mmol m-2 d-1; mean±SE, n=137 15-min bursts) but was sensitive to non-steady state changes in O2 concentrations caused by the differential advection of water masses with variable mean O2 concentrations. Important contributions to O2 eddy fluxes at surface wave frequencies were seen in eddy correlation cospectra and these are interpreted as being indicative of consumption enhanced by advective transport of O2 into the bed. The sediments were deposits of fine sand with permeabilities of 1.3-4.7×10-11 m2 and wave-generated ripples. Sediment pigment and organic carbon concentrations were low (chlorophyll-?: 0.02-0.45 ?g g-1, phaeophytin-?: 0.38-1.38 ?g g-1 and organic carbon: 0.05-0.39% dry wt in discrete depth intervals from cores collected between March and October), but it was evident that during the summer fresh pigments were trapped in the sand and rapidly mixed over the uppermost 0-13 cm. From these results it is inferred that physical forcing associated largely with waves and currents may accentuate the role of sediment-covered inner shelf habitats as a regional O2 sink compared to the middle shelf. In effect, the action of waves and currents in the benthic boundary layer enables aerobic respiration that counterbalances the oxygenation of the water column by primary production and mixing in the surface layer.

  18. 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.

  19. 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.

  20. NOAA Technical Memorandum ERL GLERL-45 THE CYCLING OF TOXIC ORGANICS IN THE

    E-print Network

    DEPARTMENT OF COMMERCE NATIONAL OCEANIC AND Enwronmental Research ATMOSPHERIC ADMINISTRATION Laboratories Characteristics of the Nepheloid Layer 7.3 Spatial Characteristics of the Nepheloid Layer 7.4 The Vertical Flux Metal Contaminants 81 8.4 Directions 86 ROLE OF BENTHIC INVERTEBRATES IN THE FATE OF POLLUTANTS

  1. Dynamics of the bathyal Benthic Boundary Layer in the northwestern Mediterranean: depth and temporal variations in macrofaunal–megafaunal communities and their possible connections within deep-sea trophic webs

    Microsoft Academic Search

    Joan E. Cartes

    1998-01-01

    The distribution patterns of benthopelagic fauna and the macrofauna–megafauna trophic relationships in the Benthic Boundary Layer (BBL) were studied. The study is based on data collected during 6 sampling cruises off the Catalan coast (western Mediterranean) during 1991–1995 at depths ranging from 389–1355 m. Crustaceans were the dominant benthopelagic macrofauna in the BBL level closest to the sea bed (~0–1.5

  2. Variability of bottom nepheloid layers near the Flower Garden Banks, Gulf of Mexico

    E-print Network

    Cecil, Thomas Martin

    1983-01-01

    Locations of July 1981 PHZSH stations. Densely spaced East Flower Garden stations are identified in Figure 5 13 Locations of July 1981 East Flower Garden pHISH stations. Mooring positions for all six current meter array deployments from January 1979... (~) and bottom transmissivity of July 1981 PHISH stations. Linear BNL sites and bottom transmissivity of the densely spaced East Plower Garden stations are indicated in Pigure 20. . 58 20 Linear BNL sites (w) and bottom transmissivity of July 1981 East...

  3. 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 ?15N 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 ?15N, with the exception of 22:6?3, which was positively correlated with ?15N, 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 ?6 PUFA, especially 20:4?6 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 ?15N and high levels of certain PUFA in samples with lower ?15N, 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.

  4. Benthic Invertebrate Biomonitoring

    NSDL National Science Digital Library

    1999-01-01

    The Environmental Protection Agency's Great Lakes National Program Office (GLNPO), which has sampled for plankton and nutrients since the 1980's, has recently made available results from the 1997 Great Lakes benthic invertebrate biomonitoring study. These data incorporate results from the program's first year of operation; samples were collected at 45 stations during the 1997 summer survey, in nearshore and offshore communities. Results (in summary and table format) include a project introduction (including color maps and figures), site description, substrate characteristics, benthic community description, and distribution of Diporeia hoyi.

  5. Seafloor Geomorphology as Benthic Habitat

    E-print Network

    Wright, Dawn Jeannine

    #12;Seafloor Geomorphology as Benthic Habitat Peter T. Harris Senior Marine Science Advisor #12;Seafloor Geomorphology as Benthic Habitat. DOI: © 2012 Elsevier Inc. All rights reserved.2012 10.1016/B978-0-12-385140-6.00058-X Seamounts, Ridges, and Reef Habitats of American Samoa Dawn J. Wright1

  6. Benthic boundary mixing and resuspension induced by internal seiches

    Microsoft Academic Search

    M. Gloor; A. Wtiest; M. Mtinnich

    1994-01-01

    The effect of internal seiches on horizontal hypolimnetic bottom currents and on the stationary well-mixed benthic boundary layer (BBL) induced by these currents was studied for 2 weeks in a small prealpine lake using thermistor strings, an acoustic current meter and a CTD (C: conductivity, T: temperature, D: depth) equipped with a transmissometer. 150 profiles of temperature, conductivity and transmissivity

  7. Benthic behavior of planktic foraminifera

    NASA Astrophysics Data System (ADS)

    Hilbrecht, Heinz; Thierstein, Hans R.

    1996-03-01

    In culture containers with sediment on the bottom, two of six species of planktic foraminifera reveal characteristic benthic activities, such as reorientation, crawling, and burrowing. Globigerinella siphonifera creates well-organized burrows and excavated sediment on a circular pile. Globorotalia menardii and Globigerinella siphonifera have specific crawling and burrowing orientations, with crawling speeds of up to 1 mm/min and burrowing speeds of 0.5 2 mm/hr. Globigerinoides ruber, Globigerinoides sacculifer, Hastigerina pelagica, and Orbulina universa did not exhibit any benthic activity and died on sediment substrates. The ability to live in a benthic mode may be a strategy in species adapted to the deep chlorophyll maximum, or neritic environments, where they exploit floating organic aggregates (marine snow) as a pseudobenthic habitat and a source of food. Benthic and pseudobenthic behavior may have been widespread in Mesozoic planktic foraminifera and may explain their widespread occurrence in epicontinental seas.

  8. 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...

  9. Woody Vegetation Removal Stimulates Riparian and Benthic

    E-print Network

    Dodds, Walter

    soil and selected benthic compartments were measured seasonally in naturally grass-domi- nated riparian removal soils. Dif- ferences in the presence and abundance of benthic compartments reflected riparian, altered grazing pressure, and changes in fire regimes (that is, frequency and intensity of fire; Briggs

  10. Interactions Between Benthic Macroalgal and Microalgal Mats

    E-print Network

    McGlathery, Karen

    -growing filamentous or sheet-like algae on the sediment or floating at the water surface. Benthic microalgal mats turnover time of algae-bound nutrients a key factor in nutrient retention. The MA-MPB coupling cannot and benthic microalgae Macro- and Microorganisms in Marine Sediments Coastal and Estuarine Studies 60

  11. Hyperspectral image unmixing over benthic habitats

    Microsoft Academic Search

    Miguel Vélez-Reyes; Samuel Rosario-Torres; James A. Goodman; Enid M. Alvira; Alexey Castrodad

    2007-01-01

    Benthic habitats are the different bottom environments as defined by distinct physical, geochemical, and biological characteristics. Hyperspectral remote sensing has great potential to map and monitor the complex dynamics associated with estuarine and nearshore benthic habitats. However, utilizing hyperspectral unmixing to map these areas requires compensating for variable bathymetry and water optical properties. In this paper, we compare two methods

  12. Benthic habitat mapping using hyperspectral remote sensing

    Microsoft Academic Search

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

    2006-01-01

    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

  13. 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 Publishers.

  14. Identification of the Photosynthetic Pigments of the Tropical Benthic Dinoflagellate Gambierdiscus toxicus

    E-print Network

    Identification of the Photosynthetic Pigments of the Tropical Benthic Dinoflagellate Gambierdiscus. toxicus strains as well as ABSTRACT-Photosynthetic pigments of the Floridn isolate ofGambierdiscus toxicus isolates. The pigments were separated using thin-layer chromatography (FLC). Tentative pigment

  15. Benthic foraminiferal distribution and recolonization of formerly anoxic environments in Drammensfjord, southern Norway

    Microsoft Academic Search

    E. Alve

    1995-01-01

    Investigations of living (stained) benthic foraminifera in the surface (0–1 cm) sediments along a depth transect in Drammensfjord, southern Norway, have been carried out on samples collected in 1984 and during all four seasons in 1988. The transect runs through strongly variable environments from a well oxygenated, brackish surface layer to anoxic waters of slightly less than normal marine salinity.

  16. 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...

  17. Quality assessment of benthic macroinvertebrates under the scope of WFD using BAT, the Benthic Assessment Tool

    Microsoft Academic Search

    Heliana Teixeira; João Magalhães Neto; Joana Patrício; Helena Veríssimo; Rute Pinto; Fuensanta Salas; João Carlos Marques

    2009-01-01

    Assessing the health of ecosystems has become a focal point among researchers worldwide. Recently, the European Water Framework Directive intensified the development of approaches to assess ecosystems’ ecological quality. The Benthic Assessment Tool (BAT) is a multimetric approach to evaluate condition of subtidal soft bottom macroinvertebrates of coastal and transitional waters. The effects of anthropogenic disturbances on benthic macroinvertebrate communities,

  18. The role of benthic foraminifera in the benthic nitrogen cycle of the Peruvian oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Glock, N.; Schönfeld, J.; Eisenhauer, A.; Hensen, C.; Mallon, J.; Sommer, S.

    2012-12-01

    The discovery that foraminifera are able to use nitrate instead of oxygen as energy source for their metabolism has challenged our understanding of nitrogen cycling in the ocean. It was evident before that only prokaryotes and fungi are able to denitrify. Rate estimates of foraminiferal denitrification were very sparse on a regional scale. Here, we present estimates of benthic foraminiferal denitrification rates from six stations at intermediate water depths in and below the Peruvian oxygen minimum zone (OMZ). Foraminiferal denitrification rates were calculated from abundance and assemblage composition of the total living fauna in both, surface and subsurface sediments, as well as from individual species specific denitrification rates. A comparison with total benthic denitrification rates as inferred by biogeochemical models revealed that benthic foraminifera account for the total denitrification on the shelf between 80 and 250 m water depth. They are still important denitrifiers in the centre of the OMZ around 320 m (29-56% of the benthic denitrification) but play only a minor role at the lower OMZ boundary and below the OMZ between 465 and 700 m (3-7% of total benthic denitrification). Furthermore, foraminiferal denitrification was compared to the total benthic nitrate loss measured during benthic chamber experiments. Foraminiferal denitrification contributes 1 to 50% to the total nitrate loss across a depth transect from 80 to 700 m, respectively. Flux rate estimates ranged from 0.01 to 1.3 mmol m-2 d-1. Furthermore we show that the amount of nitrate stored in living benthic foraminifera (3 to 705 µmol L-1) can be higher by three orders of magnitude as compared to the ambient pore waters in near surface sediments sustaining an important nitrate reservoir in Peruvian OMZ sediments. The substantial contribution of foraminiferal nitrate respiration to total benthic nitrate loss at the Peruvian margin, which is one of the main nitrate sink regions in the world oceans, underpins the importance of previously underestimated role of benthic foraminifera in global biochemical cycles.

  19. RELATIONSHIPS BETWEEN BENTHIC ORGANIC MATTER AND MACROINVERTEBRATES IN SAND SUBSTRATES

    E-print Network

    Notre Dame, University of

    RELATIONSHIPS BETWEEN BENTHIC ORGANIC MATTER AND MACROINVERTEBRATES IN SAND SUBSTRATES OF NORTHERN #12;RELATIONSHIPS BETWEEN BENTHIC ORGANIC MATTER AND MACROINVERTEBRATES IN SAND SUBSTRATES OF NORTHERN studied in sand habitats, despite the abundance of sand in many streams. These relationships were

  20. Early diagenesis and nutrient benthic fluxes in the Adriatic Sea

    NASA Astrophysics Data System (ADS)

    Spagnoli, F.; Frascari, F.; Marcaccio, M.; Bergamin, M. C.

    2003-04-01

    Early diagenesis processes and dissolved nutrient benthic fluxes of Northern and Central Adriatic Sea bottom sediments were investigate in order to know different sedimentary environmental settings. The study was carried out in 12 stations by means of an integrated analysis of pore water and solid phase composition. In each station one core, about one meter long, was collected. In the solid phase the following parameters were determined: grain size, mineralogy, Fe, Mn, Ca, Mg, Al, S, organic carbon, total nitrogen, total P. In pore waters nitrate, nitrite, ammonia, phosphate, alkalinity, sulphate, Fe, Mn and silica were analysed. Benthic fluxes were measured in situ, by benthic chamber, and calculated by modelisation of pore waters. In each station also the chemical-physical parameters of water column were measured. The area North of the Po River is characterised mainly by carbonate sediments, by low phosphate fluxes towards water column, in some cases even negative, due to authigenic apatite precipitation and by low ammonia fluxes for low reactive organic matter inputs. Near Tagliamento and Adige-Brenta river mouths sediments are higher in organic matter contents in comparison with offshore areas. In these environments pore water nutrient regeneration takes place in the uppermost centimetres of sediment by oxic and suboxic organic matter degradation (Adige-Brenta prodelta sediments) or at higher depth by organic matter degradation, mainly anoxic, via sulphate reduction (Tagliamento prodelta area). Fluxes of phosphate and TCO2 in these two areas are slowly higher than other North Po River areas. The Po River proximal prodelta area is characterised by high ammonia, phosphate and TCO2 fluxes due to high organic matter and silicate inputs, degrading mainly in anoxic conditions by sulphate reduction. When bottom water column reach anoxic conditions in these areas also Fe, Mn and phosphate fluxes increase for dissolution of Fe and Mn oxi-hydroxide surface layer. South of the Po River lower fresh organic matter and silicate inputs give place to weaker early diagenesis processes and nutrient benthic fluxes. In the Pomo Pit sediments are characterised by oxic conditions in uppermost centimetres. They are due to very low inputs of fresh organic matter and produce low fluxes of all nutrients with the exception of nitrate that flows into the sediment for oxidation processes that take place in first centimetres.

  1. CODIS Fraser River Benthic Invertebrates Table of Contents

    E-print Network

    ;______________________________________________________________________________ ______________________________________________________________________________ CODIS Fraser River Benthic Invertebrates Table of Contents Page Table of Contents i List of Figures iii ______________________________________________________________________________ ______________________________________________________________________________ CODIS Fraser River Benthic Invertebrates Appendix III: Data Appraisal 3.1 Protocol Document 65 Appendix ______________________________________________________________________________ ______________________________________________________________________________ CODIS Fraser River Benthic Invertebrates List of Figures Page Figure 1. The Fraser River basin and sub

  2. 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 nutrient concentration was compared with field collected data. The model results showed a good agreement with field measurements. From the model results, the followings are determined and discussed: (1) the role of benthic fluxes on the water quality of the reservoir (2) the extent of benthic fluxes to which the water quality exceeds the criteria.

  3. Alkanes and alkenes in marine benthic algae

    Microsoft Academic Search

    W. W. Youngblood; M. Blumer

    1973-01-01

    Saturated and olefinic hydrocarbons were determined in additional species of benthic marine algae from the Cape Cod (Massachusetts, USA) area (see: Youngblood et al., 1971). The distribution of homologous and isomeric olefins was studied in plants of different age and in morphologically different parts of the same specimen. With two minor exceptions, only normal alkanes and alkenes are present. The

  4. Pacific walrus: Benthic bioturbator of Beringia

    Microsoft Academic Search

    G. Carleton Ray; Jerry McCormick-Ray; Peter Berg; Howard E. Epstein

    2006-01-01

    The dependency of walruses on sea ice as habitat, the extent of their feeding, their benthic bioturbation and consequent nutrient flux suggest that walruses play a major ecological role in Beringia. This suggestion is supported by several lines of evidence, accumulated during more than three decades of enquiry and leading to the hypothesis that positive feedbacks of walrus feeding strongly

  5. 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 spectrum. The light intensities reaching the Foraminifera in cultivation however largely depend on the substrate provided (e.g. sand and silt where individuals dig close to the surface or coral rubble used as shelter by the Foraminiferans and as an easy way of retaining the organisms within a designated container by the investigator).

  6. The role of benthic foraminifera in the benthic nitrogen cycle of the Peruvian oxygen minimum zone

    NASA Astrophysics Data System (ADS)

    Glock, N.; Schönfeld, J.; Eisenhauer, A.; Hensen, C.; Mallon, J.; Sommer, S.

    2013-07-01

    The discovery that foraminifera are able to use nitrate instead of oxygen as an electron acceptor for respiration has challenged our understanding of nitrogen cycling in the ocean. It was thought before that only prokaryotes and some fungi are able to denitrify. Rate estimates of foraminiferal denitrification have been very sparse and limited to specific regions in the oceans, not comparing stations along a transect of a certain region. Here, we present estimates of benthic foraminiferal denitrification rates from six stations at intermediate water depths in and below the Peruvian oxygen minimum zone (OMZ). Foraminiferal denitrification rates were calculated from abundance and assemblage composition of the total living fauna in both surface and subsurface sediments, as well as from individual species specific denitrification rates. A comparison with total benthic denitrification rates as inferred by biogeochemical models revealed that benthic foraminifera probably account for the total denitrification in shelf sediments between 80 and 250 m water depth. The estimations also imply that foraminifera are still important denitrifiers in the centre of the OMZ around 320 m (29-50% of the benthic denitrification), but play only a minor role at the lower OMZ boundary and below the OMZ between 465 and 700 m (2-6% of total benthic denitrification). Furthermore, foraminiferal denitrification has been compared to the total benthic nitrate loss measured during benthic chamber experiments. The estimated foraminiferal denitrification rates contribute 2 to 46% to the total nitrate loss across a depth transect from 80 to 700 m, respectively. Flux rate estimates range from 0.01 to 1.3 mmol m-2 d-1. Furthermore we show that the amount of nitrate stored in living benthic foraminifera (3 to 3955 ?mol L-1) can be higher by three orders of magnitude as compared to the ambient pore waters in near-surface sediments sustaining an important nitrate reservoir in Peruvian OMZ sediments. The substantial contribution of foraminiferal nitrate respiration to total benthic nitrate loss at the Peruvian margin, which is one of the main nitrate sink regions in the world ocean, underpins the importance of the previously underestimated role of benthic foraminifera in global biogeochemical cycles.

  7. 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

  8. 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

    Since the changes in the economies in the Black Sea countries in the 1990's, the momentarily associated decrease in anthropogenic pressures has put the ecosystem of Black Sea western shelf on a trajectory to recovery. However, the suspected non-linearity of recovery and the ecological instability of the benthic shelf ecosystem in particular became evident in the field surveys supported by the BSERP in 2003, 2004, 2005 and 2006, e.g. in the spread of opportunistic species taking new niches and the re-occurrence of large-scale bottom water hypoxia like in 2001. The temporal dynamics of the recovery (as well as of the decline) may also be tied to climatic effects. The Black Sea is known to respond to north Atlantic oscillation (NAO) forcing and decadal climate changes. The target of the 363th cruise of R/V Poseidon in March 2008 has been to map the current state of the benthic ecosystem in a quasi-winter situation. We assessed: a) the current state of the benthic ecosystem on the north-western shelf; to what degree it recovered during the past decade from its collapse in the 1980's. In this respect, we investigated the role of the seabed as storage media of nutrients from past eutrophication, and the role of the sediments as internal source of nutrients to the pelagic system. We focused on zoo- and phytobenthos distribution, the interaction of benthic biota with the sediment, accumulation of nutrients in the sediment, and the flux of nutrients from the sediments to the water. b) The benthic-pelagic coupling, i.e. how the nutrients nitrogen, phosphorus and silica for algal growth are transported from the seafloor to the sea surface and thus fuel biologic productivity. c) The exchange of water between the shelf and the open Black Sea, and hence the transport of nutrients, i.e. the fertilization of the open Black Sea with nutrients from the shelf. Here, we are presenting results from the spring 2008 survey and compare them to findings from a summer survey in 2006: 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.

  9. 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.

  10. Microbial mediation of benthic biogenic silica dissolution

    NASA Astrophysics Data System (ADS)

    Holstein, Jan M.; Hensen, Christian

    2010-10-01

    Pore water profiles from 24 stations in the South Atlantic (located in the Guinea, Angola, Cape, Guyana, and Argentine basins) show good correlations of oxygen and silicon, suggesting microbially mediated dissolution of biogenic silica. We used simple analytical transport and reaction models to show the tight coupling of the reconstructed process kinetics of aerobic respiration and silicon regeneration. A generic transport and reaction model successfully reproduced the majority of Si pore water profiles from aerobic respiration rates, confirming that the dissolution of biogenic silica (BSi) occurs proportionally to O2 consumption. Possibly limited to well-oxygenated sediments poor in BSi, benthic Si fluxes can be inferred from O2 uptake with satisfactory accuracy. Compared to aerobic respiration kinetics, the solubility of BSi emerged as a less influential parameter for silicon regeneration. Understanding the role of bacteria for silicon regeneration requires further investigations, some of which are outlined. The proposed aerobic respiration control of benthic silicon cycling is suitable for benthic-pelagic models. The empirical relation of BSi dissolution to aerobic respiration can be used for regionalization assessments and estimates of the silicon budget to increase the understanding of global primary and export production patterns.

  11. Benthic primary production in the Columbia River Estuary. Final report

    SciTech Connect

    McIntire, C.D.; Amspoker, M.C.

    1984-02-01

    The general objective of the research associated with the Benthic Primary Production Work Unit of Columbia River Estuary Development Program was to determine mechanisms that control the production dynamics and species composition of benthic plant assemblages in the Columbia River Estuary. In particular, the work was concerned with effects of selected physical variables on structural and functional attributes of micro- and macro- vegetation, and on the productivity and biomass of benthic autotrophs on the tidal flats of the estuary.

  12. Benthic Habitat Mapping using Hyperspectral Remote Sensing Prof. Miguel Velez-Reyes

    E-print Network

    Frandsen, Jannette B.

    Benthic Habitat Mapping using Hyperspectral Remote Sensing Prof. Miguel Velez-Reyes Director for evaluating the complex spatial dynamics associated with estuarine and nearshore benthic habitats, such as coastal optical water properties and constituents, benthic habitat composition, and bathymetry

  13. 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...

  14. Benthic fluxes in San Francisco Bay

    USGS Publications Warehouse

    Hammond, D.E.; Fuller, C.; Harmon, D.; Hartman, B.; 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 variability is smaller, probably because the annual temperature range in San Francisco Bay is smaller. Budgets constructed for South San Francisco Bay show that large fractions of the net annual productivity of carbon (about 90%) and silica (about 65%) are recycled by the benthos. Substantial rates of simultaneous nitrification and denitrification must occur in shoal areas, apparently resulting in conversion to N2 of 55% of the particulate nitrogen reaching the sediments. In shoal areas, benthic fluxes can replace the water column standing stocks of ammonia in 2-6 days and silica in 17-34 days, indicating the importance of benthic fluxes in the maintenance of productivity. Pore water profiles of nutrients and Rn-222 show that macrofaunal irrigation is extremely important in transport of silica, ammonia, and alkalinity. Calculations of benthic fluxes from these profiles are less accurate, but yield results consistent with chamber measurements and indicate that most of the NH3, SiO2, and alkalinity fluxes are sustained by reactions occurring throughout the upper 20-40 cm of the sediment column. In contrast, O2, CO2, and N + N fluxes must be dominated by reactions occurring within the upper one cm of the sediment-water interface. While most data support the statements made above, a few flux measurements are contradictory and demonstrate the complexity of benthic exchange. ?? 1985 Dr W. Junk Publishers.

  15. MDE NON-TIDAL BENTHIC MACROINVERTEBRATE MONITORING PROGRAM

    EPA Science Inventory

    The Maryland Non-tidal Benthic Macroinvertebrate Monitoring Program provides data on benthic macroinvertebrates for many streams in the state. Through it, an entire network of 100 stations in the nontidal reaches of Marylands Chesapeake Bay Basin are sampled within a two year per...

  16. FRESHWATER POTOMAC LONG-TERM BENTHIC MONITORING PROGRAM

    EPA Science Inventory

    The Maryland Department of the Environments Freshwater Potomac Long-Term Benthic Monitoring Program provides seasonal information on abundance and composition for the benthic fauna of the freshwater portion of the Potomac River for use in recommendations to State agencies accordi...

  17. Global environmental predictors of benthic marine biogeographic structure

    E-print Network

    Boyce, C. Kevin

    of the benthic marine biota, at the 1° grid-cell resolution. These analyses demonstrate the cen- tral role changes in climate. bivalves | climate | macroecology | sea-surface temperature Biogeographic units (BUs that determine the biogeographic structure of benthic marine species in shallow-water habitats, where marine bio

  18. Monitoring of Benthic Reference Sites: Using an Autonomous Underwater Vehicle

    Microsoft Academic Search

    Stefan Williams; Oscar Pizarro; Michael Jakuba; Craig Johnson; Neville Barrett; Russell Babcock; Gary Kendrick; Peter Steinberg; Andrew Heyward; Peter Doherty; Ian Mahon; Matthew Johnson-Roberson; Daniel Steinberg; Ariell Friedman

    2012-01-01

    We have established an Australia-wide observation program that exhibits recent developments in autonomous underwater vehicle (AUV) systems to deliver precisely navigated time series benthic imagery at selected reference stations on Australia's continental shelf. These observations are designed to help characterize changes in benthic assemblage composition and cover derived from precisely registered maps collected at regular intervals. This information will provide

  19. 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.

  20. Prediction of Benthic Impact for Salmon Net-Pens Based on the Balance of Benthic Oxygen Supply and Demand

    Microsoft Academic Search

    R. H. Findlay; Les Watling

    1997-01-01

    The ratio between oxygen supply and oxygen demand was examined as a predictor of benthic response to organic enrichment caused by salmon net-pen aquaculture. Oxygen supply to the benthos was calculated based on Fickian diffusion and near-bottom flow velocities. A strong linear correlation was found between measured carbon sedimentation rates and rates of benthic metabolism. This relationship allowed an estimation

  1. New Benthic ?18o 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 ?18O of formainiferal calcite is a common paleoceanographic proxy, which measures ice volume and deep water temperature change. Foraminiferal ?18O is also often used to create marine sediment core age models by aligning down-core variations in ?18O to a global stack, or average. However, the most commonly used stack, known as "LR04," has an outdated age model, assumes global benthic ?18O synchrony, and is biased to the Atlantic [Lisiecki and Raymo, 2005]. Here we present six regional benthic ?18O 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 ?18O 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 ?18O 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.

  2. Diel variability in seawater pH relates to calcification and benthic community structure on coral reefs.

    PubMed

    Price, Nichole N; Martz, Todd R; Brainard, Russell E; Smith, Jennifer 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

  3. 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

  4. 3.6 BENTHIC INVERTEBRATE COMMUNITY STRUCTURE by Trefor B. Reynoldson

    E-print Network

    109 3.6 BENTHIC INVERTEBRATE COMMUNITY STRUCTURE 3.6 by Trefor B. Reynoldson National Water Department of Fisheries and Oceans Winnipeg, Manitoba BENTHIC INVERTEBRATE COMMUNITY STRUCTURE Benthic numerous sites. #12;110 3.6 BENTHIC INVERTEBRATE COMMUNITY STRUCTURE The concept of a reference condition

  5. 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...

  6. 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...

  7. CHECKLIST AND BIBLIOGRAPHY OF THE MARINE BENTHIC ALGAE

    E-print Network

    Mcilwain, Jenny

    are technical/environmental reports, i.e., grey literature, which mention or list marine benthic algae in the Literature Cited section, 107 of the citations are published papers. One unpublished M.S. thesis (Potter

  8. 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...

  9. 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...

  10. Mapping of benthic enrichment patterns in Narragansett Bay, Rhode Island

    Microsoft Academic Search

    Raymond M. Valente; Donald C. Rhoads; Joseph D. Germano; Victor J. Cabelli

    1992-01-01

    A synoptic reconnaissance survey was performed over a five-day period in August 1988 to assess benthic habitat quality throughout\\u000a Narragansett Bay, Rhode Island, using REMOTS® sediment-profile photography and analysis in combination with measurements of the levels ofClostridium perfringens spores (a fecal indicator) in sediments. Three main areas of degraded benthic habitat quality related to either excessive\\u000a organic enrichment or physical

  11. Magnesium content of calcite in carapaces of benthic armine Ostracoda

    E-print Network

    Cadot, H. M.; Kaesler, R. L.

    1977-07-22

    THE UNIVERSITY OF KANSAS PALEONTOLOGICAL CONTRIBUTIONS July 22, 1977 Paper 87 MAGNESIUM CONTENT OF CALCITE IN CARAPACES OF BENTHIC MARINE OSTRACODA 1 H. MEADE CADOT, JR.,2 and ROGER L. KAESLER3 2 Antioch College—New England and The Harris Center... for Conservation Education, Hancock, New Hampshire; 'The University of Kansas, Lawrence ABSTRACT Statistically significant differences in mean magnesium content of calcite in carapaces of benthic marine Ostracoda were found to occur among four superfamily groups...

  12. Phototoxicity of TiO? nanoparticles to a freshwater benthic amphipod: are benthic systems at risk?

    PubMed

    Li, Shibin; Wallis, Lindsay K; Ma, Hongbo; Diamond, Stephen A

    2014-01-01

    This study investigated phototoxicity of TiO? nanoparticles (nano-TiO?) 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 performed using dynamic light scattering, UV/Vis spectroscopy, and Scanning Electron Microscopy. Large agglomeration and sedimentation (>77%) in LSW was observed after 0.5h. A simulated solar radiation (SSR)-favored surface attachment of nanoparticles was observed, indicating enhanced phototoxicity with the increased attachment. A 96-h median lethal concentration (LC50) of 29.9 mg/L in H. azteca was calculated, with a daily 4-h UV exposure of 2.2 W/m(2). Phototoxicity of nano-TiO? under SSR had a 21-fold increase as compared to that under ambient laboratory light. This phototoxicity was also dependent on UV dose, with calculated LC50s around 22.9 (95% CI, 20.5-23.3)Wh/m(2) when exposed to 20 mg/L nano-TiO?. Also, H. azteca exhibited negative phototaxis in the presence of shelters, indicating that other factors might play a role in environmental systems. Finally, the environmental implications of nano-TiO? to benthic organisms were illustrated, emphasizing the importance of various environmental factors in the ultimate phototoxicity. This increased phototoxicity and its complex interactions with various environmental factors suggest further investigations are needed for future risk assessment of photoactive nanomaterials to benthic organisms. PMID:23973546

  13. The continental shelf benthic iron flux and its isotope composition

    NASA Astrophysics Data System (ADS)

    Severmann, Silke; McManus, James; Berelson, William M.; Hammond, Douglas E.

    2010-07-01

    Benthic iron fluxes from sites along the Oregon-California continental shelf determined using in situ benthic chambers, range from less than 10 ?mol m -2 d -1 to values in excess of ˜300 ?mol m -2 d -1. These fluxes are generally greater than previously published iron fluxes for continental shelves contiguous with the open ocean (as opposed to marginal seas, bays, or estuaries) with the highest fluxes measured in the regions around the high-sediment discharge Eel River and the Umpqua River. These benthic iron fluxes do not covary with organic carbon oxidation rates in any systematic fashion, but rather seem to respond to variations in bottom water oxygen and benthic oxygen demand. We hypothesize that the highest rates of benthic iron efflux are driven, in part, by the greater availability of reactive iron deposited along these river systems as compared to other more typical continental margin settings. Bioirrigation likely plays an important role in the benthic Fe flux in these systems as well. However, the influence of bottom water oxygen concentrations on the iron flux is significant, and there appears to be a threshold in dissolved oxygen (˜60-80 ?M), below which sediment-ocean iron exchange is enhanced. The isotope composition of this shelf-derived benthic iron is enriched in the lighter isotopes, and appears to change by ˜3‰ (? 56Fe) during the course of a benthic chamber experiment with a mean isotope composition of -2.7 ± 1.1‰ (2 SD, n = 9) by the end of the experiment. This average value is slightly heavier than those from two high benthic Fe flux restricted basins from the California Borderland region where ? 56Fe is -3.4 ± 0.4‰ (2 SD, n = 3). These light iron isotope compositions support previous ideas, based on sediment porewater analyses, suggesting that sedimentary iron reduction fractionates iron isotopes and produces an isotopically light iron pool that is transferred to the ocean water column. In sum, our data suggest that continental shelves may export a higher efflux of iron than previously hypothesized, with the likelihood that along river-dominated margins, the benthic iron flux could well be orders of magnitude larger than non-river dominated shelves. The close proximity of the continental shelf benthos to the productive surface ocean means that this flux is likely to be essential for maintaining ecosystem micronutrient supply.

  14. 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 biologists group were combined in order to derive roughness lengths from abundance measurements of four previously selected key species which represent the originators of the dominating benthic structures at the sea floor in the south-western Baltic Sea. Critical shear stress velocity and bed roughness are known at few sample sites only. They were extrapolated into the larger investigation area using a proxy-target concept. The mean near bottom milieu (bathymetry, median grain size, salinity, oxygen) which was derived using results from numerical modelling serves as the proxy. Since the milieu parameters are measured at the sampling sites for which the target parameters have been determined, a combined hierarchical and supervised classification was employed to transfer the local knowledge into the unknown investigation area.

  15. 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.

  16. 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...

  17. Effects of Copper Pollution on the Benthic Community in the Le An River, China

    Microsoft Academic Search

    Muqi Xu; Jiang Zhu; Hong Cao

    2003-01-01

    Pollution by heavy metals and acid mine wastewater completely eradicated the benthic community from a section of the Le An River, China. Downstream changes in the benthic community directly reflected the degree of metal pollution in the sediments.

  18. Acoustic scattering by benthic and planktonic shelled animals Timothy K. Stanton and Dezhang Chu

    E-print Network

    Stanton, Tim

    Acoustic scattering by benthic and planktonic shelled animals Timothy K. Stanton and Dezhang Chu of shell Littorina littorea . Benthic and planktonic shelled animals with this shape occur on the seafloor

  19. Benthic Macroinvertebrate Assemblages in the Near Coastal Zone of Lake Erie

    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...

  20. Effects of mussel filtering activity on boundary layer structure

    Microsoft Academic Search

    Luca A. van Duren; Peter M. J. Herman; Adri J. J. Sandee; Carlo H. R. Heip

    2006-01-01

    The structure of the benthic boundary layer over a bed of mussels (Mytilus edulis) was investigated in a large racetrack flume. Flow was observed to be modified both by the physical roughness of the mussel bed and by the momentum input of the exhalent jets of the mussels. Particularly when the mussels were closed, and filtering activity was reduced to

  1. Flow structures of the Benthic Ocean

    Microsoft Academic Search

    Laurence Armi; Eric D'Asaro

    1980-01-01

    Three-dimensional structure of the near-bottom density field was observed with a towed yo-yoing profiler and a fixed current\\/temperature measuring array on the Hatteras abyssal plain. A great variety of structures were seen. Immediately above the bottom a well-mixed bottom layer extends vertically 5-60 m, with less than 1 m°C potential temperature change. This mixed layer is often capped by a

  2. Middlelate Miocene benthic foraminifera in a western equatorial Indian Ocean depth transect: Paleoceanographic implications

    E-print Network

    Royer, Dana

    Middle­late Miocene benthic foraminifera in a western equatorial Indian Ocean depth transect Miocene (17­5 Ma) benthic foraminiferal faunas (N63 m) from a depth transect in the western equatorial reserved. Keywords: Miocene; Benthic foraminifera; Indian Ocean; Paleoceanography; Monsoon; ODP 1

  3. 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...

  4. SURVEY OF THE BENTHIC INVERTEBRATE FAUNA OF THE EASTERN BERING SEA

    E-print Network

    401 SURVEY OF THE BENTHIC INVERTEBRATE FAUNA OF THE EASTERN BERING SEA SPECIAL SCIENTIFIC REPORTMMERfiiAL Fisheries, Donald L. McKernan, Director SURVEYOR THE BENTHIC INVERTEBRATE FAUNA OF THE EASTERN BERING SEA;#12;SURVEY OF THE BENTHIC INVERTEBRATE FAUNA OF THE EASTERN BERING SEA by Patsy A. McLaughlin Fishery

  5. Early Cretaceous benthic associations (foraminifera and calcareous algae) of a shallow tropical-water platform

    E-print Network

    Husinec, Antun

    Early Cretaceous benthic associations (foraminifera and calcareous algae) of a shallow tropical of benthic foraminifera and calcareous algae in order to establish a precise, combined benthic biozonation species of calcareous algae, distributed among 11 genera, were recovered from the Lower Cretaceous shallow

  6. LINKING BENTHIC ALGAL BIOMASS TO STREAM SUBSTRATUM TOPOGRAPHY1 Justin N. Murdock2

    E-print Network

    Kaufman, Glennis A.

    effect on benthic algal development. Considerable research has been conducted on the effectsLINKING BENTHIC ALGAL BIOMASS TO STREAM SUBSTRATUM TOPOGRAPHY1 Justin N. Murdock2 and Walter K of substrata significantly influence benthic algal development. We explored the relationships among substratum

  7. Anomalous shifts in tropical Pacific planktonic and benthic foraminiferal test size during the PaleoceneEocene

    E-print Network

    Zachos, James

    Anomalous shifts in tropical Pacific planktonic and benthic foraminiferal test size during-dwelling planktonic foraminifera, and the stable carbon and oxygen isotope ratios of benthic foraminifera and bulk in the size of surface-water planktonic in contrast to deep-water benthic foraminifera which decrease in size

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

    Microsoft Academic Search

    Steven P. Ferraro; Faith A. Cole

    2011-01-01

    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

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

    Microsoft Academic Search

    Steven P. Ferraro; Faith A. Cole

    2011-01-01

    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

  10. UNIVERSITY Of HAWAII UBR.ARY BENTHIC-PELAGIC COUPLING ON THE ANTARCTIC CONTINENTAL SHELF

    E-print Network

    Luther, Douglas S.

    UNIVERSITY Of HAWAII UBR.ARY BENTHIC-PELAGIC COUPLING ON THE ANTARCTIC CONTINENTAL SHELF: IMPACTS DIVISION OF THE UNIVERSITY OF HAWAI'I IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR;minor degree in the benthic fauna. This pattern suggests substantial inertia in benthic- pelagic

  11. 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 6months later. Benthic foraminifera were separated into >150?m (large) and 63-150?m (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

  12. Benthic photosynthesis and oxygen consumption in permeable carbonate sediments at Heron Island, Great Barrier Reef, Australia

    NASA Astrophysics Data System (ADS)

    Rasheed, Mohammed; Wild, Christian; Franke, Ulrich; Huettel, Markus

    2004-01-01

    In order to investigate benthic photosynthesis and oxygen demand in permeable carbonate sands and the impact of benthic boundary layer flow on sedimentary oxygen consumption, in situ and laboratory chamber experiments were carried out at Heron Island, Great Barrier Reef, Australia. Total photosynthesis, net primary production and respiration were estimated to be 162.9±43.4, 98.0±40.7, and 64.9±15.0 mmol C m -2 d -1, respectively. DIN and DIP fluxes for these sands reached 0.34 and 0.06 mmol m -2 d -1, respectively. Advective pore water exchange had a strong impact on oxygen consumption in the permeable sands. Consumption rates in the chamber with larger pressure gradient (20 rpm, 1.2 Pa between centre and rim) simulating a friction velocity of 0.6 cm s -1 were approximately two-fold higher than in the chambers with slow stirring (10 rpm, 0.2 Pa between centre and rim, friction velocity of 0.3 cm s -1). In the laboratory chamber experiments with stagnant water column, oxygen consumption was eight times lower than in the chamber with fast stirring. Laboratory chamber experiments with Br - tracer revealed solute exchange rates of 2.6, 2.2, 0.7 ml cm -2 d -1 at stirring rates of 20, 10, and 0 rpm, respectively. In a laboratory experiment investigating the effect of sediment permeability on oxygen and DIC fluxes, a three-fold higher permeability resulted in two- to three-fold higher oxygen consumption and DIC release rates. These experiments demonstrate the importance of boundary flow induced flushing of the upper layer of permeable carbonate sediment on oxygen uptake in the coral sands. The high filtration and oxidation rates in the sub-tropical permeable carbonate sediments and the subsequent release of nutrients and DIC reveal the importance of these sands for the recycling of matter in this oligotrophic environment.

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

    USGS Publications Warehouse

    King, Jeffrey

    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.

  14. 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.

  15. Optical Delineation of Benthic Habitat Using an Autonomous

    E-print Network

    Moline, Mark

    Optical Delineation of Benthic Habitat Using an Autonomous Underwater Vehicle Mark A. Moline. Autonomous underwater vehicles AUVs with active propulsion are especially well suited for studies . Autonomous underwater vehicles AUVs are especially well suited for studies of the coastal ocean because

  16. Page 1 of 30 Fundamentals of Benthic Microbial Fuel Cells

    E-print Network

    Girguis, Peter R.

    Page 1 of 30 17 Fundamentals of Benthic Microbial Fuel Cells: Theory, Development and Application a watershed for fuel cell research, in particular for microbial fuel cells (see for example: Larminie & Dicks; Schröder, 2007; Logan, 2008). While the majority of microbial fuel cell (MFC) research has focused

  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 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...

  19. Organic ux control on bathymetric zonation of Mediterranean benthic foraminifera

    E-print Network

    Rohling, Eelco

    Organic ¯ux control on bathymetric zonation of Mediterranean benthic foraminifera S. De Rijka,1 , F ¯oor. We ®nd that most of the major taxa show a clear W to E shallowing of their upper or lower depth successions from more oligotrophic taxa at greater water depths to more eutrophic taxa in more shallow water

  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. risk: lessons from Triassic-Jurassic marine benthic organisms

    Microsoft Academic Search

    Wolfgang Kiessling; Martin Aberhan

    Aim To evaluate the influence of geographical distribution on the extinction risk of benthic marine invertebrates using data from the fossil record, both during times of background extinction and across a mass-extinction episode. Total geographical range is contrasted with proxies of global abundance to assess the relationships between the two essential components of geographical distribution and extinction risk. Location A

  2. dam logic: qualitative reasoning about benthic macroinvertebrate responses

    E-print Network

    Tullos, Desiree

    dam logic: qualitative reasoning about benthic macroinvertebrate responses to dam removal desiree reliability of biotic and abiotic indicators (e.g. responsiveness to dam removal, detectability, feasibility relationships "there appears to be a wide range of ecological responses to dam removal. It is therefore

  3. 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.

  4. 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

  5. Impact of benthic disturbance on megafauna in Central Indian Basin

    Microsoft Academic Search

    Nimi Rodrigues; Rahul Sharma; B. Nagendernath

    2001-01-01

    Deep-sea photographs and video data were studied to evaluate the effects of benthic disturbance on megafaunal distribution in the Central Indian Basin. Xenophyophores (41%) and holothurians (30%) are the most abundant taxa, followed by other groups in the area before the disturbance. An overall reduction (32%) in the total megafaunal population after disturbance is direct evidence of the impact on

  6. Development and Verification of a Benthic/Pelagic Food Web

    E-print Network

    Gobas, Frank

    Development and Verification of a Benthic/Pelagic Food Web Bioaccumulation Model for PCB Congeners of this model to predict contaminant transfer in a complex food web and its potential applicability to other food webs indicate that it could be an important tool for managing contaminants on an ecosystem level

  7. Results Of The National Benthic Surveillance Project (Pacific Coast): 1987

    Microsoft Academic Search

    Bruce B. McCain; Sin-Lam Chan; Margaret M. Krahn; Donald W. Brown; Mark S. Myers; John T. Landahl; Susan Pierce; Robert C. Clark; Usha Varanasi

    1989-01-01

    During the fourth year (1987) of the Pacific Coast portion of the National Benthic Surveillance Project (NBSP), a multiyear study of chemical contaminants and associated fish diseases at selected sites on the Pacific Coast of the United States, two embayments (San Diego Bay and San Francisco Bay) were selected for more intensive sampling in order to evaluate the magnitude of

  8. One decade of benthic macroinvertebrate biomonitoring in the River Meuse

    Microsoft Academic Search

    Henk A. M. Ketelaars; Nicole M. L. H. F. Frantzen

    1995-01-01

    The benthic macroinvertebrate community of the River Meuse was studied at four locations in Belgium and The Netherlands from 1983–1993. Macroinvertebrates were collected from artificial substrates, placed near the river bottom from June–August. The results were analyzed using autecological information. At an upstream sampling site in the Belgian Ardennes (Hastière) the most diverse fauna was found. One quarter of the

  9. Comparisons of benthic invertebrates between riffles and pools

    Microsoft Academic Search

    Arthur V. Brown; Peter P. Brussock

    1991-01-01

    Benthic species assemblages in upstream and downstream ends of riffles and in pools were investigated seasonally in the first five orders of an alluvial gravel stream with distinct pool and riffle channel form. Riffles comprised ca. 15–85% of total surface area) which was scoured during periodic high flow. Virtually all taxa were more abundant in riffles than in pools, except

  10. EFFECTS OF CONTAMINATED SEDIMENTS ON MARINE BENTHIC BIOTA AND COMMUNITIES

    EPA Science Inventory

    Our understanding of the effects of contaminants on benthic organisms lags well behind that for water column species because of the way in which sediments mediate bioavailability and because test protocols using infaunal organism are still in the developmental stage. lthough quan...

  11. Biological vs. Physical Mixing Effects on Benthic Food Web Dynamics

    Microsoft Academic Search

    Ulrike Braeckman; Pieter Provoost; Tom Moens; Karline Soetaert; Jack J. Middelburg; Magda Vincx; Jan Vanaverbeke; Andrew Wilby

    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

  12. A survey of benthic invertebrates in the Suwannee River, Florida.

    PubMed

    Mason, W T

    1991-02-01

    Benthic invertebrate communities were surveyed in a 233 km reach of the middle and lower Suwannee River in Northwestern Florida in the winter 1987 and early summer 1988 to determine their abundance and distribution as potential foods of the Gulf sturgeon, Acipenser oxyrhynchus desotoi, and to determine the effects of possible natural and human-induced disturbances to the communities. In substrates of the tidal oligohaline to mesohaline lower reach of the East Pass site I (km 2) and site II West Pass (km 5) near the Gulf of Mexico, densities of tube dwelling and free swimming amphipods, polychaetes, oligochaetes, and dipterans in the PONAR grabs were moderate (100-999 {iex} individuals/m(2)) to abundant (1000-9999 {iex} individuals m(-2)). Also, at sites I and II, low (10-99 {iex} individuals m(-2)) to moderate densities of dipteran Chironomidae and olive nerite snail were collected in hardboard multiplate artificial substrate samplers. Diversities of benthic invertebrates in both grabs and hardboard multiplates were relatively low. Baetid mayflies were moderately abundant in the dip net samples. Upriver from sites I and II, the transition of an oligohaline tolerant benthic community to a freshwater one was abrupt due to strong freshwater flow. At sites III (km 48) and IV (km 89), benthic invertebrate populations were low to moderate in hardboard multiplate and dip net samples. In the middle reach (km 101 to km 233), aquatic insects were predominant and included; chironomids, mayflies, and beetles, and also, freshwater gammarid amphipods, gastropods, and the Asian clam. In winter, the bottom substrates at sites VII (km 153) and VIII (km 205) contained diverse and dense populations of Chironomidae (5932 m(-2)), the greatest density for a major taxonomic group recorded in this survey. Crayfish were collected in low densities only in artificial substrate samplers from sites IV to IX. Leeches were widespread in the study area. Empirical Biotic Index values that reflect impacts of organic wastes on benthic invertebrate communities were within a narrow range, 3.16 to 6.38, and indicated 'slightly enriched' to 'enriched' water. Of the total 186 benthic invertebrate taxa, 82% had quality values 0 to 5 that indicate overall 'clean water' conditions. The predominant benthic invertebrates in the Suwannee River were detritivorous and the communities reflected oligotrophic to mesotrophic waters. PMID:24241891

  13. 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 standardized, identifications of species verified by trained taxonomists, and new field and laboratory studies undertaken before we can expect to obtain an accurate description of the benthic fauna and its relations with the environment.

  14. Benthic oxygen consumption on continental shelves off eastern Canada

    NASA Astrophysics Data System (ADS)

    Grant, Jonathan; Emerson, Craig W.; Hargrave, Barry T.; Shortle, Jeannette L.

    1991-08-01

    The consumption of phytoplankton production by the benthos is an important component of organic carbon budgets for continental shelves. Sediment texture is a major factor regulating benthic processes because fine sediment areas are sites of enhanced deposition from the water column, resulting in increased organic content, bacterial biomass and community metabolism. Although continental shelves at mid- to high latitudes consist primarily of coarse relict sediments ( PIPER, Continental Shelf Research, 11, 1013-1035), shelf regions of boreal and subarctic eastern Canada contain large areas of silt and clay sediments ( FADER, Continental Shelf Research, 11, 1123-1153). We collated estimates of benthic oxygen consumption in coarse (<20% silt-clay, <0.5% organic matter) and fine sediments (20% silt-clay, 0.5% organic matter) for northwest Atlantic continental shelves including new data for Georges Bank, the Scotian Shelf, the Grand Banks of Newfoundland and Labrador Shelf. Estimates were applied to the areal distribution of sediment type on these shelves to obtain a general relationship between sediment texture and benthic carbon consumption. Mean benthic oxygen demand was 2.7 times greater in fine sediment than in coarse sediment, when normalized to mean annual temperature. In terms of carbon equivalents, shelf regions with minimal fine sediment (Georges Bank, the Grand Banks of Newfoundland-northeast Newfoundland) consumed only 5-8% of annual primary production. Benthos of the Gulf of Maine (100% fine sediment) and the Scotian Shelf (35% fine sediment) utilized 16-19% of primary production. Although 32% of the Labrador Shelf area contained fine sediments, benthic consumption of pelagic production (8%) was apparently limited by low mean annual temperature (2°C). These results indicate that incorporation of sediment-specific oxygen uptake into shelf carbon budgets may increase estimates of benthic consumption by 50%. Furthermore, respiration and production by large macrofauna allow an even greater proportion of primary production to enter benthic pathways. Fine sediment areas (shelf basins or "depocenters") are postulated to be sites of enhanced biological activity which must be considered in the modelling of shelf carbon budgets and the role of the benthos in demersal fisheries.

  15. 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.

  16. 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...

  17. Pelagic-benthic transition of the harmful alga, Heterosigma akashiwo: Changes in swimming and implications for benthic cell distributions

    Microsoft Academic Search

    Elizabeth D. Tobin; Daniel Grünbaum; Rose Ann Cattolico

    2011-01-01

    Many harmful algal blooming (HAB) species transition between a vegetative, motile phase in the water column and a dormant, non-motile resting phase in the sediments. These life history transitions potentially regulate the timing, location and persistence of bloom events. Motility promotes aggregation and influences vertical distributions in the water column. However, the contribution of this behavior to benthic distributions of

  18. Benthic Redox Conditions and Oceanographic Variability in the Upper Central Peruvian Margin since the Nineteenth Century Depicted from Benthic Foraminifera

    NASA Astrophysics Data System (ADS)

    Cardich, J.; Sifeddine, A.; Salvatecci, R.; Briceño, F. J., Sr.; Almeida, C.; Romero, D.; Gutierrez, D.

    2014-12-01

    Benthic foraminifera compose the dominant biota in the central Peruvian margin, which is impinged by an intense Oxygen Minimum Zone (OMZ). Here subsurface and benthic biogeochemical conditions are characterized by oxygen deficiency in the bottom waters, strong fluxes of settling organic matter and reducing conditions in the surface sediments. These processes interact among each other and are amplified or relaxed according to the variability of oceanic conditions at different spatial and temporal scales. Recent studies on living foraminiferal assemblages determined the association of species to a geochemical condition (in terms of redox and organic matter (OM)). Species such as Bolivina costata, Nonionella auris and Virgulinella fragilis were characteristic of sulphidic/labile OM-rich sediments, whereas Bolivina pacifica headed the assemblage representative of postoxia (no oxygen, non sulphidic)/preserved OM. The present study aims to reconstruct the decadal to multidecadal variation of benthic paleo-redox conditions for the last two centuries, based on laminated sedimentary records of benthic foraminiferal assemblages and redox-sensitive metals (Mo, Re, etc.) in the upper margin off Callao (12°S). Three major multidecadal periods were determined for the record: i) the mid to late nineteenth century, characterized by the occurrence of massive diatom-rich sedimentation events, development of bottom anoxia, and higher abundance of Bolivina costata and Nonionella auris; ii) the late nineteenth century to mid-twentieth century, featuring interdecadal variations of redox conditions; and iii) the late twentieth century until the early 2000's, in which redox-sensitive metal records exhibit a trend towards less reducing conditions, accompanied by higher relative abundances of postoxia foraminiferal species (e.g. Bolivina pacifica or Bolivina plicata). Remarkably, the first multidecadal period is associated with a higher ENSO activity, whereas the latest one is parallel to the period of coastal cooling and increasing fluxes of productivity proxies. Our findings suggest that besides export productivity, the upper margin benthic redox states are modulated by vertical mixing and/or subsurface ventilation.

  19. Changes in Antarctic Intermediate Water Revealed by Trace Metal Analysis of Benthic Foraminifera

    NASA Astrophysics Data System (ADS)

    Cook, M.; Elderfield, H.; Zahn, R.; Pahnke, K.

    2006-12-01

    Trace metal analysis of foraminifera is a well-used oceanographic tool that allows the reconstruction of paleo- temperatures, pH, carbonate ion concentrations and nutrient content of ambient waters. These analyses can be used to reconstruct the different factors affecting stable isotope systems. ?13C in foraminifera as a nutrient proxy is complicated by isotopic deviations resulting from equilibrium fractionation with the atmosphere. This can be unravelled by examination of nutrient proxies such as the cadmium content of the foraminiferal test, which co-varies with phosphate in the modern ocean. We present a high resolution record of trace metal variability from core MD97-2120, located on Chatham Rise, near New Zealand at a depth of 1210m. MD97-2120 is located close to the core layer of Antarctic Intermediate Water (AAIW), and allows reconstruction of the redistribution of heat and freshwater within the upper ocean. Benthic ?13C and ?18O and planktonic Mg/Ca have demonstrated changes in production and demonstrated Southern Hemisphere warming coincident with cooling and decreased deepwater convection in these North Atlantic. In this study we utilise trace metal analyses such as Cd/Ca and Mg/Ca of the benthic foraminifera Hoeglundina elegans, Trifarina angulosa, and Uvigerina sp. to reconstruct changes in AAIW over the previous 150ka. These measurements have a mean temporal resolution of 161 years, and allow the reconstruction of nutrient content and temperature of intermediate waters. This allows separation of air-sea exchange and nutrient signals within the ?13C record, which shows significant variations indicative of changes in sea-ice formation and motion of the Subantarctic Front. Reconstruction of water temperature from foraminiferal Mg/Ca, combined with ?18O measurements allows estimation of the AAIW salinity during the Last Glacial Maximum, demonstrating the stratification of the glacial Southern Ocean. Pahnke K., Zahn R. (2005) Science 307, 1741-1746

  20. Global Warming and Mass Mortalities of Benthic Invertebrates in the Mediterranean Sea

    PubMed Central

    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

  1. 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).

  2. Natural History of Nova Scotia Topics & Habitats: Benthic

    NSDL National Science Digital Library

    Downloadable electronic version of a section of a book of the same title; a naturalist's approach to understanding the environment of that region. A searchable summary includes brief introduction, list of headings, keyword list, and cross-references to other sections. Benthic habitats are composed of a variety of sediment types and are exposed to a wide range of water conditions, leading to the development of diverse plant and animal communities.

  3. Benthic foraminifera from polluted marine environment of Sulaibikhat Bay (Kuwait)

    Microsoft Academic Search

    A. Z. Al-Zamel; M. A. Al-Sarawi; S. R. Khader; I. A. Al-Rifaiy

    2009-01-01

    Quantitative analyses of recent benthic foraminiferal assemblages (living and dead) were carried out on the surface sediments\\u000a of Sulaibikhat Bay. Marked contrast in foraminiferal assemblages between the shallow tidal mudflats and the deep tidal channel\\u000a and their relation to the extent of pollution were observed. Cluster analysis of quantitative data on the distribution of\\u000a foraminiferal tests revealed three assemblages that

  4. A Benthic Terrain Classification Scheme for American Samoa

    Microsoft Academic Search

    Emily R. Lundblad; Dawn J. Wright; Joyce Miller; Emily M. Larkin; Ronald Rinehart; David F. Naar; Brian T. Donahue; S. Miles Anderson; Tim Battista

    2006-01-01

    Coral reef ecosystems, the most varied on earth, continually face destruction from anthropogenic and natural threats. The U.S. Coral Reef Task Force seeks to characterize and map priority coral reef ecosystems in the U.S.\\/Trust Territories by 2009. Building upon NOAA Biogeography shallow-water classifications based on Ikonos imagery, presented here are new methods, based on acoustic data, for classifying benthic terrain

  5. Macroevolutionary interplay between planktic larvae and benthic predators

    NASA Astrophysics Data System (ADS)

    Peterson, Kevin J.

    2005-12-01

    Many marine invertebrates have a complex life cycle in which the egg develops into an intermediate planktic larval form rather than developing directly to the benthic juvenile stage. Because of the evolutionary and ecological complexity of pelagic-benthic life cycles, the reasons behind the origin of larvae and their subsequent maintenance over geological time are not well understood. Using both a molecular clock and the fossil record, I show that the initial exploitation of the predator-free pelagic realm by lecithotrophic larvae was achieved independently multiple times by the end of the Early Cambrian, and that the convergent evolution of planktotrophy from lecithotrophic ancestors evolved between the latest Cambrian and Middle Ordovician at least four, and possibly as many as eight, times. Both the exploitation of the pelagic realm by nonfeeding larvae and the acquisition of planktotrophy correlate in time with novel modes of benthic predation, including the dramatic rise in the number and type of epifaunal suspension feeders in the Early Ordovician.

  6. 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

  7. 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. PMID:23262411

  8. Impact of benthic disturbance on megafauna in Central Indian Basin

    NASA Astrophysics Data System (ADS)

    Rodrigues, Nimi; Sharma, Rahul; Nagender Nath, B.

    Deep-sea photographs and video data were studied to evaluate the effects of benthic disturbance on megafaunal distribution in the Central Indian Basin. Xenophyophores (41%) and holothurians (30%) are the most abundant taxa, followed by other groups in the area before the disturbance. An overall reduction (32%) in the total megafaunal population after disturbance is direct evidence of the impact on benthic environment. Different groups such as xenophyophores, sea anemones, shrimps, starfish, brittle stars, holothurians and fish show different degrees of reduction (21-48%) in their numbers, depending upon their ability to withstand increased turbidity and sedimentation rates due to disturbance. Faunal groups such as protobranch molluscs, polychaete worms, seafans and squids, observed before the disturbance, were not seen after disturbance, whereas populations of some taxa increased after the disturbance. Increased numbers of mobile taxa could be due to increased levels of organic carbon due to resedimentation, whereas increase in sessile taxa may partly reflect the difficulty in distinguishing live from dead specimens. The impact on faunal assemblages is more severe in the disturbed area than the undisturbed area. Our results indicate that monitoring of megafauna can be used effectively to evaluate the potential impacts of large-scale mining or other disturbance on the seafloor, and may therefore help in developing measures for conservation of the benthic environment.

  9. Stoichiometry of benthic invertebrate nutrient recycling: interspecific variation and the role of body mass

    Microsoft Academic Search

    João M. Alves; Adriano Caliman; Rafael D. Guariento; Marcos P. Figueiredo-Barros; Luciana S. Carneiro; Vinicius F. Farjalla; Reinaldo L. Bozelli; Francisco A. Esteves

    2010-01-01

    Ecological stoichiometry (ES) and allometry offer frameworks for predicting how nutrient recycling varies within and among\\u000a animal species. Despite the importance of benthic-derived nutrients in most aquatic systems, predictions based on ES and allometry\\u000a have been poorly tested among benthic invertebrate consumers. Here, we show that the rates and ratios at which three freshwater\\u000a benthic invertebrate species (a crustacean, an

  10. 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....

  11. Benthic biodiversity indices versus salinity gradient in the southern Baltic Sea

    E-print Network

    Zettler, Michael

    Framework Directive (WFD) encouraged the design of specific biotic indices to evaluate the response- tive and the Water Framework Directive (WFD). Benthic invertebrates are often used as bioindicators

  12. 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 Classification Standard (CMECS) that is being modified to include all NPS needs, such as lacustrine ecosystems and submerged cultural resources. CMECS Version III (Madden and others, 2010) includes components for water column, biotic cover, surface geology, sub-benthic, and geoform. SBMP Data Archiving. The SBMP calls for the storage of all raw data and final products in common-use data formats. The concept of 'collect once, use often' is essential to efficient use of mapping resources. Data should also be shared with other agencies and the public through various digital clearing houses, such as Geospatial One-Stop (http://gos2.geodata.gov/wps/portal/gos). To be most useful for managing submerged resources, the SBMP advocates the inventory and mapping of the five components of marine ecosystems: surface geology, biotic cover, geoform, sub-benthic, and water column. A complete benthic inventory of a park would include maps of bathymetry and the five components of CMECS. The completion of mapping for any set of components, such as bathymetry and surface geology, or a particular theme (for example, submerged aquatic vegetation) should also include a printed report.

  13. 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 (²¹?Pb, ²³?Th), 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-term effects of the DWH event on a larger spatial scale. PMID:25785988

  14. 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-term effects of the DWH event on a larger spatial scale. PMID:25785988

  15. Continuous and simultaneous cultivation of benthic food diatom Nitzschia sp. and abalone Haliotis sieboldii by using deep seawater.

    PubMed

    Fukami; Kawai; Asada; Okabe; Hotta; Moriyama; Doi; Nishijima; Yamaguchi; Taniguchi

    1998-12-01

    By using low-temperature, clean, and nutrient-rich properties of deep seawater (DSW; seawater below the euphotic layer), a continuous and simultaneous cultivation system for a benthic food diatom, Nitzschia sp., and juvenile abalone was established. Cell suspension of Nitzschia sp. was added to a bioreactor made of acrylic pipe (7 cm diameter x 50 cm long) containing short vinyl tubes (2 cm diameter x 2 cm long) as substrata. DSW collected from 320 m depth at Muroto City, in Kochi Prefecture, Japan, was supplied to the reactor and incubated under natural light (ca. 6000 lux) with a continuous DSW flow rate of 40 turnovers per hour. After growing enough benthic diatoms in the reactor, juveniles of abalone, Haliotis sieboldii (shell length ca. 10-20 mm) were put into a reactor, and cultivated simultaneously with food diatoms in the continuous flow system. During the four-month incubation, 7-month-old abalone juveniles with a shell length of 12.4 (average) +/-0.2 (SD) mm were grown to 19.4 (+/-1.7) mm in the reactor. Daily growth rates of abalones were 50-110 µm/day. These results indicate that the continuous cultivation system with DSW supports the growth of juvenile abalone without any supply of seaweed until it grows to release size. PMID:9852618

  16. 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...

  17. Cranberry Bogs: The effect of cultivation and restoration on habitat distribution, benthic invertebrate communities, and food webs in stream ecosystems

    E-print Network

    Vallino, Joseph J.

    invertebrate communities, and food webs in stream ecosystems Kimberly Morrell Department of Biology, Carleton habitat distribution, benthic invertebrate communities, and food webs in stream ecosystems. To understand transects and analyzed benthic invertebrate samples. Stable isotope analyses clarified the relationships

  18. 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...

  19. Deep Sea Benthic Foraminifera: Love Cold, Fear Warm

    NASA Astrophysics Data System (ADS)

    Thomas, E.

    2007-12-01

    The fossil record provides understanding of possible linkages between long-term environmental changes and evolution of assemblages and morphological species of deep-sea benthic foraminifera, of which the phylogeny is still little known. Deep-sea benthic foraminifera have long morphological species lives and do not commonly suffer massive extinctions: they live in the largest habitat on earth, species have large geographic ranges or are cosmopolitan, and they use motile propagules to rapidly re-populate regions where populations have been destroyed. Extinction occurs only when rapid and severe environmental change affects such a large part of the deep ocean that no refugia exist, even for common species. Deep-sea benthic foraminifera reacted to global cooling (in the earliest Oligocene, middle Miocene and middle Pleistocene) not by extinction, but by a gradual turnover of species. The most extensive turnover occurred in the late Eocene through earliest Oligocene, when some presently important ecological niches were first filled. In contrast, deep-sea benthic foraminifera suffered severe extinction (30-50% of species, including common, cosmopolitan, long-lived species) during the rapid global warming of the Paleocene-Eocene Thermal Maximum (PETM), a time of high CO2 levels and potential ocean acidification. The extinction was followed by slow recovery of faunas, but diversity never returned to pre-extinction levels. The PETM and later, less severe short-term periods of global warming (hyperthermals ETM1 and ETM2) were characterized by low diversity faunas dominated by small, thin-walled individuals. No significant net extinction occurred during the later hyperthermals. Such faunas might reflect dissolution, low oxygen conditions, or blooming of opportunistic species after environmental disturbance. Most commonly cited causes of the PETM extinction are: 1. low oxygen concentrations, 2. acidification of the oceans, 3. increase or decrease in oceanic productivity and/or transfer of food to the sea floor, and 4. increasing temperatures. All 4 factors may have contributed to the extinction, but the first three factors varied regionally and by depth, whereas only the temperature increase affected the deep-sea environment globally. High temperatures not only increase overall metabolic rates, but also affect which species of prokaryotes are most active and which labile compounds they generate, thus the compounds and the amount of labile organic matter available for foraminiferal feeding. At sites along a depth transect at Walvis Ridge (SE Atlantic) species that earlier had been abundant in neritic waters ( Tappanina selmensis) increased strongly in abundance. Some surviving deep-sea species underwent diversification and morphological evolution; during and just after the PETM and two other hyperthermal events the deep-sea genus Abyssamina became more abundant (most pronounced at the deeper sites), while evolving into several morphological species. During the warmer intervals its aperture became more irregular in shape, with an extremely asymmetrical shape at the deepest site during ETM1. The aperture in benthic foraminifera directs the streaming of pseudopods, thus the way of food intake, suggesting that the nature of benthic feeding changed during the warm periods. During the early Eocene (a period characterized by hyperthermals), faunas maintained larger differences in assemblage composition between ocean basins than before the extinction. It remains a question whether this faunal heterogeneity reflects the mode of deep-ocean circulation/ventilation during the warmest period of the Cenozoic.

  20. Managing mangroves with benthic biodiversity in mind: Moving beyond roving banditry

    Microsoft Academic Search

    Aaron M. Ellison

    2008-01-01

    This review addresses mangrove management activities in the broader context of the diversity of the mangrove benthos. Goals for mangrove ecosystem management include silviculture, aquaculture, or ‘ecosystem services’ such as coastal protection. Silvicultural management of mangroves generally neglects the benthos, although benthic invertebrates may affect tree establishment and growth, and community composition of benthic invertebrates may be a reliable indicator

  1. MARYLAND DEPARTMENT OF THE ENVIRONMENT NON-TIDAL BENTHIC MACROINVERTEBRATE MONITORING PROGRAM

    EPA Science Inventory

    The Maryland Non-tidal Benthic Macroinvertebrate Monitoring Program provides data on benthic macroinvertebrates for many streams in the state. Through it, an entire network of 100 stations in the nontidal reaches of Marylands Chesapeake Bay Basin are sampled within a two year per...

  2. MIDDLE REACH OF THE SNAKE RIVER: WATER QUALITY AND BENTHIC BIOMONITORING

    EPA Science Inventory

    This study examined spatial and temporal trends in water quality, sestonic and benthic algal concentrations, and benthic macroinvertebrate taxa richness, population density, and biomass at nine stations along the Middle Snake River from Pillar Falls to Upper Salmon Falls Dam. Pri...

  3. Using benthic infauna abundance and genetic markers in oysters as indicators of hypoxia downstream from a

    E-print Network

    Vallino, Joseph J.

    Using benthic infauna abundance and genetic markers in oysters as indicators of hypoxia downstream on communities downstream from these systems has not been well assessed. This study sought to examine differences ways: (1) chemical analysis of the sediment, (2) abundance of benthic infauna, and (3) oyster response

  4. Estuarine, Coastal and Shelf Science (1985) 21,357-364 Estimation of Benthic Respiration

    E-print Network

    1985-01-01

    Estuarine, Coastal and Shelf Science (1985) 21,357-364 Estimation of Benthic Respiration Parameters emphasized the importance of benthic respiration and nutrient regeneration to the understanding respiration of the accumulated organic detritus on the bottom in combination with the onsetof increasedwater

  5. Journal of Marine Research, 55,785~812, 1997 Digestive environments of benthic macroinvertebrate guts

    E-print Network

    Jumars, Pete

    Journal of Marine Research, 55,785~812, 1997 Digestive environments of benthic macroinvertebrate Hydrolytic enzyme activity, surfactancy, and dissolved organic matter in the digestive lumens of 19 benthic evidence for micelles. While enzymes reflected the biochemical nature of the digestible food substrate

  6. 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.

  7. Early Cenozoic benthic foraminiferal isotopes: Species reliability and interspecies correction factors

    E-print Network

    Royer, Dana

    isotopic offsets appear to have changed through the Cenozoic, either (1) as a result of evolutionaryEarly Cenozoic benthic foraminiferal isotopes: Species reliability and interspecies correction to reconstruct past ocean and climate conditions, with those of benthic foraminifera providing information

  8. Application of Benthic Foraminiferal Mg\\/Ca Ratios to Questions of Cenozoic Climate Change

    Microsoft Academic Search

    K. Billups; D. Schrag

    2002-01-01

    We investigate the evolution of Cenozoic climate and ice volume as evidenced by the oxygen isotopic composition of seawater derived from benthic foraminiferal Mg\\/Ca ratios to constrain the temperature effect contained in foraminiferal oxygen isotope values values. We have constructed two benthic foraminiferal Mg\\/Ca records from intermediate water depth sites (Ocean Drilling Program sites 757 and 689 from the subtropical

  9. Descriptive ecology of offshore, deep-water, benthic algae in the temperate western North Atlantic Ocean

    Microsoft Academic Search

    J. R. Sears; R. A. Cooper

    1978-01-01

    The vertical distribution, floristic composition and habitat ecology of sublittoral, benthic algae are described for two deep water, offshore stations in the Gulf of Maine, based on in situ observations and collections to 47 m depth during SCUBA and submarine dives. Twenty species of macroscopic algae were collected between 29 and 45 m. These occurred in two benthic algal associations:

  10. Use of Benthic Macroinvertebrates to Evaluate Stream Water Quality in Trinidad and Tobago, West Indies

    Microsoft Academic Search

    L. D. Maharaj; M. Alkins-Koo

    2005-01-01

    In order to determine the best method of using benthic macroinvertebrates to monitor water quality in Trinidad and Tobago, 63 sites along 38 streams were sampled in each of the wet and dry seasons from 1999-2001. At each site, 5 benthic samples were collected with a 300mum 'D' frame kicknet, along with data for 14 environmental parameters and habitat data.

  11. www.cerf-jcr.org Benthic Nitrogen Fixation in an Eutrophic Estuary Affected

    E-print Network

    www.cerf-jcr.org Benthic Nitrogen Fixation in an Eutrophic Estuary Affected by Groundwater.A., 2012. Benthic nitrogen fixation in an eutrophic estuary affected by groundwater discharge. Journal- derived nutrient loading is known to initiate coastal eutrophication, hypoxia, and harmful algal blooms

  12. The distribution of juvenile benthic invertebrates in an arctic glacial fjord

    Microsoft Academic Search

    Ingo Fetzer; Ole Lønne; Tom Pearson

    2002-01-01

    The distribution of juvenile benthic invertebrates with respect to their abiotic environment was investigated at four locations along a gradient in Kongsfjorden (79°N, 12°E), Spitsbergen, in September 1997. Heavy discharge of inorganic sediments released by the three glaciers was expected to be one of the main structuring factors of benthic communities in the fjord. Juveniles of 76 species\\/families are identified.

  13. Fish and Benthic Invertebrates: Community Concordance and Community-Environment Relationships

    E-print Network

    Jackson, Don

    Fish and Benthic Invertebrates: Community Concordance and Community-Environment Relationships, Canada Jackson, D.A., and H.H. Harvey. 1993. Fish and benthic invertebrates: community concordance in small, shallow lakes than in larger lakes. The invertebrate community was not correlated with lake

  14. 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.

  15. IMPORTANCE OF PHYSICAL SCALING FACTORS TO BENTHIC MARINE INVERTEBRATE RECOLONIZATION OF LABORATORY MICROCOSMS

    EPA Science Inventory

    Five laboratory studies of benthic macroinvertebrate recolonization were conducted for 6-wk periods to evaluate the effects of physical factors (i.e., microcosm size, seawater flow rates and sediment depth) on benthic community structure. esign variables included4 open-faced acry...

  16. Pelagic–benthic coupling in the western Barents Sea: Processes and time scales

    Microsoft Academic Search

    Paul E. Renaud; Nathalie Morata; Michael L. Carroll; Stanislav G. Denisenko; Marit Reigstad

    2008-01-01

    The link between pelagic and benthic systems has been suggested to be particularly strong on Arctic continental shelves. Differing sampling strategies and the multitude of pelagic and benthic parameters that have been compared, however, make it difficult to determine the limitations of this important ecosystem concept. We sampled across multiple gradients in water mass characteristics, ice cover, productivity regimes, and

  17. Relationship Between Benthic Fluxes and Macrophyte Cover in a Shallow Brackish Lagoon

    Microsoft Academic Search

    P. Viaroli; M. Bartoli; I. Fumagalli; G. Giordani

    1997-01-01

    The relationship between macrophyte cover and benthic fluxes of oxygen, nutrients and sulphide has been examined in a shallow fishpond with a nearly homogeneous meadow of Ruppia cirrhosa (Petagna) Grande (Bassin d'Arcachon, western France). In 1993 and 1994, benthic fluxes were measured in early and late summer. These periods were selected to represent the production and decay phases of Ruppia

  18. Biodiversity assessment of benthic macroinvertebrates in altitudinal lotic ecosystems of Serra do Cipó (MG, Brazil)

    Microsoft Academic Search

    N. GALDEAN; M. CALLISTO; F. A. R. BARBOSA

    2001-01-01

    Five lotic systems of Serra do Cipó, south-east Brazil, were investigated in order to assess the existing diversity of benthic macroinvertebrates, habitats-microhabitats, and the available trophic resources. For each river it was analysed the communities of benthic macroinvertebrates and the com- position of some taxonomic groups (Plecoptera, Ephemeroptera, Trichoptera and Diptera Chirono- midae): the community with Bivalvia Sphaeriidae, Oligochaeta and

  19. Retardation of Phosphate Release from Freshwater Benthic Sediments by Application of Ocher Pellets with Calcium Nitrate

    Microsoft Academic Search

    Yu-Mee Na; Seok S. Park

    2004-01-01

    This article presents an in situ treatment method for retardation of phosphate release from freshwater benthic sediments. The method is based on the addition of ocher pellets into benthic sediments. The pellets consist of ocher and calcium nitrate (OCN pellet). The OCN pellet slowly releases calcium and nitrate, together with ocher, into the sediment–water interface, where all three components play

  20. 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...

  1. Impacts of altered benthic invertebrate communities on the feeding ecology of yellow

    E-print Network

    Rasmussen, Joseph

    of benthic macroinvertebrate communities. Benthic macroinvertebrates and yellow perch (Perca flavescens) were prélevé des macroinvertébrés benthiques et des perchaudes (Perca flavescens) dans six lacs le long d). For example, young-of-the-year yellow perch (Perca flavescens) are predominantly pelagic foragers. By the end

  2. Functional Morphology of the Pectoral Fins in Bamboo Sharks, Chiloscyllium plagiosum: Benthic vs. Pelagic

    E-print Network

    Lauder, George V.

    Functional Morphology of the Pectoral Fins in Bamboo Sharks, Chiloscyllium plagiosum: Benthic vs that observed previously in sturgeon and leopard sharks. During sinking, the pectoral fins are held concave. KEY WORDS: bamboo shark; locomotion; station-holding; benthic; pectoral fin; flow visualization

  3. Deep-sea benthic community and environmental impact assessment at the Atlantic Frontier

    Microsoft Academic Search

    John D Gage

    2001-01-01

    The seabed community provides a sensitive litmus for environmental change. North Sea analysis of benthic populations provides an effective means for monitoring impacts from man's interventions, such as offshore oil exploitation and fishing, against baseline knowledge of the environment. Comparable knowledge of the benthic biology in the deep waters of the Atlantic Frontier beyond the N.E. Atlantic shelf edge is

  4. Assessing acid stress in Swedish boreal and alpine streams using benthic macroinvertebrates

    Microsoft Academic Search

    Leonard Sandin; Joakim Dahl; Richard K. Johnson

    2004-01-01

    Sixty streams in northern Sweden were sampled for benthic macroinvertebrates in spring and autumn of 2000 as part of the European Union project AQEM (the Development and Testing of an Integrated Assessment System for the Ecological Quality of Streams and Rivers throughout Europe using Benthic Macroinvertebrates). Samples were taken using a harmonised multi-habitat sampling procedure and a large number of

  5. The use of benthic mesocosms for the assessment of sediment contamination

    Microsoft Academic Search

    R. Fletcher; T. B. Reynoldson; W. D. Taylor

    2001-01-01

    The diagnostic capability of changes in the benthic macroinvertebrate community composition to determine the cause in contaminated sediments were addressed using box core mesocosms subjected to cadmium, atrazine and nutrient enrichment. Intact cores of lake sediment were collected from Lake Erie at four occasions during 1996 and were returned to laboratory where they were maintained and manipulated. The benthic community

  6. 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...

  7. Autonomous video camera system for monitoring impacts to benthic habitats from demersal fishing gear, including longlines

    Microsoft Academic Search

    Robert Kilpatrick; Graeme Ewing; Tim Lamb; Dirk Welsford; Andrew Constable

    2011-01-01

    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

  8. WALRUS, ODOBENUS ROSMARUS, FEEDING IN THE BERING SEA: A BENTHIC PERSPECTIVE

    E-print Network

    WALRUS, ODOBENUS ROSMARUS, FEEDING IN THE BERING SEA: A BENTHIC PERSPECTIVE JOHN S. OLIVER,' PETER N. SLATTERY,1 EDMUND F. O'CONNOR,1 AND LLOYD F. LOWRy2 ABSTRACT Walrus, Odobenus rosmarus, feed with scuba Documentation of this benthic feeding record suggested that walrus com- monly search for visually

  9. EFFECTS OF PENTACHLOROPHENOL ON FIELD- AND LABORATORY-DEVELOPED ESTUARINE BENTHIC COMMUNITIES

    EPA Science Inventory

    A study of the response of benthic communities exposed to pentachlorophenol (PCP) was conducted to obtain additional information on the effects of this widely used chemical on the estuarine environment and to compare its effect on estuarine benthic communities developed in the fi...

  10. 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

  11. 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 we know now that we did not a decade ago. PMID:17405206

  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. PMID:23950956

  13. Carbon and oxygen isotope geochemistry of live (stained) benthic foraminifera from the Aleutian Margin and the Southern Australian Margin

    E-print Network

    Levin, Lisa

    Carbon and oxygen isotope geochemistry of live (stained) benthic foraminifera from the Aleutian October 2008 Accepted 4 November 2008 Keywords: stable isotopes benthic foraminifera 13C 18O deep sea-water geochemistry and stable isotopic values of the tests of living (stained) calcareous benthic foraminifera from

  14. Fine-Scale Distribution and Spatial Variability of Benthic Invertebrate Larvae in an Open Coastal Embayment in

    E-print Network

    deYoung, Brad

    Fine-Scale Distribution and Spatial Variability of Benthic Invertebrate Larvae in an Open Coastal- scale (0.5 km) of variability in the horizontal distributions of benthic invertebrate larvae and related (2014) Fine-Scale Distribution and Spatial Variability of Benthic Invertebrate Larvae in an Open Coastal

  15. Development of filamentous green algae in the benthic algal community in a littoral sand-beach zone of Lake Biwa

    Microsoft Academic Search

    Kentaro Nozaki; Khadbaatar Darijav; Tetsuji Akatsuka; Naoshige Goto; Osamu Mitamura

    2003-01-01

    Temporal changes of biomass and dominant species in benthic algal communities were investigated in a littoral sand-beach zone in the north basin of Lake Biwa from December 1999 to September 2000. Chlorophyll- a amounts of benthic algal communities per unit area of the sandy sediments rapidly increased from late April to June. Increases in biomass of the benthic algal communities

  16. Effects of thermal effluents on communities of benthic marine macroalgae

    SciTech Connect

    Devinny; J.S.

    1980-11-01

    Surveys of marine benthic macro-algae were made at two study areas receiving thermal effluents from power plants. A third, at an area where a natural thermal gradient exists, was investigated for comparison. Ordination analysis of the algal communities indicated changes in species composition of about 10% for each degree of temperature change up to 3/sup 0/C. Temperatures 7/sup 0/C above ambient altered the algal community by eliminating the large phaeophytes. Temperatures 10/sup 0/C above ambient left only a species-poor community of ephemeral populations.

  17. 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 ?13C, with glycine the most enriched in 13C and leucine the most depleted in 13C. Specific amino acids including phenylalanine showed spatial variability in ?13C and ?15N values within the sampled area, indicating contributions of different dietary sources including phytoplankton, sea ice algae, benthic algae and terrestrial organic materials. ?15N values of individual amino acids such as the difference between glutamic acid and phenylalanine, i.e. ?15Nglu-phe (?15Nglu - ?15Nphe), were also used to identify trophic levels of benthic invertebrates relative to estimates available from bulk ?15N 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.

  18. 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

  19. Particulate matter in the south Atlantic Ocean 

    E-print Network

    Wood, Megan Maria

    1993-01-01

    p increases near the seafloor, indicating the presence of a nepheloid layer. In the Argentine Basin, the nepheloid layer is intense and widespread. Maximum c p there reaches 1.175 m-1 (approximately 1750 ug/1). The Brazil Basin has the lowest...

  20. Spatially-explicit hydrologic controls on benthic invertebrate habitat suitability

    NASA Astrophysics Data System (ADS)

    Ceola, Serena; Bertuzzo, Enrico; Singer, Gabriel; Battin, Tom; Montanari, Alberto; Rinaldo, Andrea

    2014-05-01

    Streamflow variability is a major determinant of basin-scale distribution of benthic invertebrates. Here we present a probabilistic approach for a spatially explicit quantitative assessment of benthic invertebrate abundance as derived from near-bed flow variability throughout an entire stream network. We consider aquatic invertebrates as these are widely employed as sensitive indicators of fluvial ecosystem health and human-induced perturbations. Moving from the analytical characterization of site-specific probability distribution functions of streamflow and bottom shear stress, we achieve a spatial extension to a stream network ranging up to 5th order. Bottom shear stress distributions, coupled with habitat suitability curves derived from field studies, are then used to produce maps of invertebrate habitat suitability based on shear stress conditions. The proposed framework allows to inspect the possible impacts of human-induced perturbations of streamflow variability on river ecology. We apply our approach to an Austrian river network, for which rainfall and streamflow time series, river network hydraulic properties and local information on invertebrate abundance for a limited number of sites are available. This allows a comparison between observed species density versus modeled habitat suitability based on shear stress. Although the proposed strategy neglects ecological determinants other than hydraulic ones and thus represents an ecological minimal model, it allows derivation of important implications of water resource management and fluvial ecosystem protection for basin-scale distribution patterns of organisms.

  1. Hydrologic controls on basin-scale distribution of benthic invertebrates

    NASA Astrophysics Data System (ADS)

    Ceola, Serena; Bertuzzo, Enrico; Singer, Gabriel; Battin, Tom J.; Montanari, Alberto; Rinaldo, Andrea

    2014-04-01

    Streamflow variability is a major determinant of basin-scale distributions of benthic invertebrates. Here we present a novel procedure based on a probabilistic approach aiming at a spatially explicit quantitative assessment of benthic invertebrate abundance as derived from near-bed flow variability. Although the proposed approach neglects ecological determinants other than hydraulic ones, it is nevertheless relevant in view of its implications on the predictability of basin-scale patterns of organisms. In the present context, aquatic invertebrates are considered, given that they are widely employed as sensitive indicators of fluvial ecosystem health and human-induced perturbations. Moving from the analytical characterization of site-specific probability distribution functions of streamflow and bottom shear stress, we achieve a spatial extension to an entire stream network. Bottom shear stress distributions, coupled with habitat suitability curves derived from field studies, are used to produce maps of invertebrate suitability to shear stress conditions. Therefore, the proposed framework allows one to inspect the possible impacts on river ecology of human-induced perturbations of streamflow variability. We apply this framework to an Austrian river network for which rainfall and streamflow time series, river network hydraulic properties, and local information on invertebrate abundance for a limited number of sites are available. A comparison between observed species density versus modeled suitability to shear stress is also presented. Although the proposed strategy focuses on a single controlling factor and thus represents an ecological minimal model, it allows derivation of important implications for water resource management and fluvial ecosystem protection.

  2. Resolution of paleobathymetric trends using benthic foraminiferal morphometrics

    SciTech Connect

    Gary, A.C.; Healy-Williams, N.

    1986-05-01

    Foraminiferal species exhibit a wide range of morphological characteristics, some of which are a reflection of the environment of their habitat. These ecophenotypic responses may provide a powerful clue to determining past depositional environments. In most morphologic studies of benthic foraminifera, relationships have been shown between test size and water depth and between surface sculpture and water depth. The authors applied an automated imaging system to examine the morphology of three species of Bolivina from the northwestern Gulf of Mexico. Two of the three species analyzed displayed clear relationships with test shape and water depth. Overall test shape appeared to be the most important discriminator of depth, but changes in the periphery (i.e., spinosity) of the foraminifera were also noted in one species. All of these results clearly indicate that the test shape of benthic foraminifera hold the possibility of providing facies information to paleontologists. Importantly, these results indicate that imaging techniques are capable of distinguishing changes in shape with depth. The quantification of these changes offers the possibility of precise and rapid depth determinations with an accuracy and resolution not possible with many other techniques.

  3. 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

  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. Earth's Layers

    NSDL National Science Digital Library

    Mrs. Walls

    2011-01-30

    Complete a poster all about Earth's Layers! Directions: Make a poster about Earth's Layers. (20 points) Include at least (1) large picture (15 points) on your poster complete with labels of every part (10 points). (15 points) Include at least three (3) facts about Earth's Layers. (5 points each) (15 points) Write at least a three sentence summary of your poster ...

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

    SciTech Connect

    Stair, D.M. Jr.; 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.

  7. 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/Thioploca mat to a constant or seasonal seepage of methane at the continental slope off Pakistan. Surprisingly, however, stable oxygen isotope values of many species and especially of U. peregrina decrease with depth, which calls into question the suitability of U. peregrina as a recorder of bottom-water ?18O.

  8. 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.

  9. Photoinduced toxicity of fluoranthene to seven marine benthic crustaceans.

    PubMed

    Boese, B L; Lamberson, J O; Swartz, R C; Ozretich, R J

    1997-05-01

    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 differences between LC50s and EC50s before and after UV exposure were used to assess photoinduced toxicity. UV exposure enhanced fluoranthene toxicity by as much as tenfold in five of the seven species tested (Rhepoxynius abronius, Eohaustorius estuarius, Leptocheirus plumulosus, Grandidierella japonica, and Corophium insidiosum). Species having the greatest potential for natural exposure to sunlight (Excirolana vancouverensis and Emerita analoga) were the least sensitive to photoinduced fluoranthene toxicity. Although photoinduced toxicity needs to be considered in environmental risk assessments, testing should be done, using ecologically relevant species and exposures. PMID:9175504

  10. 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

  11. Effect of exposure method on benthic organism responses

    SciTech Connect

    Rowland, C.; Burton, G.A. Jr. [Wright State Univ., Dayton, OH (United States). Biological Sciences Dept.

    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.

  12. Acoustic scattering by benthic shells: Dominant scattering mechanisms and applications

    NASA Astrophysics Data System (ADS)

    Stanton, Timothy K.; Chu, Dezhang

    2004-10-01

    When benthic shells occur in sufficiently large numbers, they can dominate acoustic backscattering by the seafloor, especially at angles of incidence away from normal. In order to use sound as a tool to remotely detect and quantify the shells, the scattering properties of the shells need to be understood, both in free-space as well as when placed on the seafloor. Through laboratory experimentation, it has been determined that the edges of certain types of shells (such as bivalves and sand dollars) can dominate the scattering over an important range of grazing angles. The surfaces of these shells and others dominate under other conditions. The dominant scattering effects are discussed in the context of interpreting acoustic backscatter data in terms of meaningful parameters such as numerical density of the shells.

  13. Disturbance frequency influences patch dynamics in stream benthic algal communities.

    PubMed

    Ledger, Mark E; Harris, Rebecca M L; Armitage, Patrick D; Milner, Alexander M

    2008-04-01

    Disturbance is integral to the organisation of riverine ecosystems. Fluctuating low flows caused by supra-seasonal drought and water management periodically dewater habitat patches, potentially creating heterogeneity in the taxonomic composition and successional dynamics of benthic communities. The frequency of disturbance induced by low flows is contingent upon the topography of the river bed and thus varies among patches. We investigated whether the frequency of patch dewatering influenced the structure and temporal dynamics of benthic algal communities attached to the upper surfaces of stones in stream mesocosms (4 m2). In a 693-day disturbance experiment, we applied short dewatering disturbances (6 days) at high (33-day cycles) and low frequencies (99-day cycles) and compared algal assemblages with undisturbed controls at 21 endpoints. In the absence of disturbance, epilithic space was dominated by the green encrusting alga Gongrosira incrustans. However, drying disturbances consistently reduced the dominance of the green alga, and crust abundance decreased with increasing disturbance frequency, thereby opening space for a diversity of mat-forming diatoms. The response of mat diatoms to disturbance varied markedly during the experiment, from strong reductions in the abundance of loosely attached mats in mid-late 2000 to the exploitation of open space by closely adhering mats in 2001. Contrary responses were attributed to changes in the species composition of mat diatoms, which influenced the physiognomy and hence stress-resistance and resilience of the assemblage. Our results indicate that patchy dewatering of habitat patches during periods of low flow influences the successional dynamics of algae, thereby creating distinctive mosaics on the stream bed. PMID:18193289

  14. 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.

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

    SciTech Connect

    Lenihan, H.; Oliver, J.S. [Moss Landing Marine Labs., CA (United States)

    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.

  16. 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. PMID:22605471

  17. 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 briefly, but severely destabilized the oceanic phytoplankton food webs. Isothermal Remanent Magnetization (IRM) curves treated by the cumulative log-Gaussian function shows that hematite (or goethite) and magnetite are the main magnetic minerals in the K/Pg clay layer, whereas large and small magnetite characterize the Maastrichtian and the Danian sediments, respectively. The dominance of hematite over magnetite at the K/Pg boundary explains the lack of the characteristic positive magnetic susceptibility peak observed in other sections suggesting higher oxidation state of the Galanderud depositional environment during the impact. The presence of three calcareous dinoflagellate chalk layers and large excursions in O- and C-isotopic compositions in basal Danian Zone P0 highlight the instability of the ecosystem immediately following the K/Pg boundary. In the Parvularugoglobigerina eugubina and Parasubbotina pseudobulloides Zones, there is an increase in both diversity and infaunal morphogroups, and a slight decrease of the epifaunal morphogroups; some deeper species increase in abundance including Gyroidinoides globosus and Marssonella oxycona. These changes might indicate a sea level rise and uppermost bathyal paleodepths in the early Danian, but it might also indicate improved conditions at the seafloor including greater flux of organic matter. These abrupt paleoenvironmental changes at the K/Pg boundary are correlated in age to the Chicxulub impact event and to the Deccan Phase 2; the contribution of each event is currently under study.

  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. BENTHIC MICROBIAL RESPIRATION IN APPALACHIAN MOUNTAIN, PIEDMONT, AND COASTAL PLAINS, STREAMS OF THE EASTERN USA

    EPA Science Inventory

    Our study had two objectives. First, in order to quantify the potential underestimation of community respiration caused by the exclusion of anaerobic processes, we compared benthic microbial respiration measured as 02 consumption with estimated based on DHA. Second, our previous ...

  20. 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...

  1. Rates of Benthic Protozoan Grazing on Free and Attached Sediment Bacteria Measured with Fluorescently Stained Sediment

    PubMed Central

    Starink, Mathieu; Krylova, Irina N.; Bär-Gilissen, Marie-José; Bak, Rolf P. M.; Cappenberg, Thomas E.

    1994-01-01

    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-1 h-1 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. PMID:16349315

  2. 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...

  3. 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...

  4. 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...

  5. A Characterization of Benthic Macroinvertebrate Communities in Agricultural Drainage Ditches of the Northeast Arkansas Delta, USA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Agricultural drainage ditches have large differences in hydroperiod and provide additional water residence time to mitigate farm runoff before it reaches receiving water bodies. These ditch wetland habitats harbor a characteristic benthic macroinvertebrate fauna reflective of the assimilative capac...

  6. 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 ...

  7. Patterns in biodiversity and distribution of benthic Polychaeta in the Mississippi Canyon, Northern Gulf of Mexico 

    E-print Network

    Wang, Yuning

    2006-04-12

    The distribution of benthic polychaetes in the Mississippi Canyon was examined to evaluate impacts of environmental variables on species assemblages. Environmental variables considered included depth, bathymetric slope, hydrographic features...

  8. Prepared in cooperation with the U.S. Bureau of Reclamation Quantifying the Benthic Source of

    E-print Network

    Prepared in cooperation with the U.S. Bureau of Reclamation Quantifying the Benthic Source of the Interior U.S. Geological Survey #12;Prepared in cooperation with the U.S. Bureau of Reclamation Quantifying

  9. 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...

  10. 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...

  11. Depth dependency of the Paleocene-Eocene carbon isotope excursion: Paired benthic and terrestrial biomarker records

    E-print Network

    Zachos, James

    biomarker records (Ocean Drilling Program Leg 208, Walvis Ridge) H. McCarren Earth and Planetary Sciences of the Paleocene-Eocene carbon isotope excursion: Paired benthic and terrestrial biomarker records (Ocean Drilling

  12. 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...

  13. DISCRIMINATING THE BENTHIC EFFECTS OF ANTHROPOGENIC POINT SOURCES FROM SALINITY AND NITROGEN LOADING

    EPA Science Inventory

    To evaluate the influence of anthropogenic point sources on estuarine systems, environmental managers must be able to discern the level and effects of significant natural factors and nonpoint source inputs. We compared benthic community state, salinity and dissolved inorganic nit...

  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 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...

  15. 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,...

  16. 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...

  17. 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...

  18. 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...

  19. 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...

  20. Benthic invertebrate assemblage in Samborombón River (Argentina, S. America), a brackish plain river

    Microsoft Academic Search

    Fernando Spaccesi; Alberto Rodrigues Capítulo

    2009-01-01

    The spatial and temporal differences in the structure and composition of benthic invertebrates were studied at three sites\\u000a of the Samborombón River, which is an important tributary of the Río de la Plata Estuary (Argentina), having a low slope and\\u000a brackish drainage. Biological samples were taken during each season. Physico-chemical variables were measured to determine\\u000a their association in the benthic

  1. 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 summer than in spring, in turn suggesting an important role of macrofauna bioturbation and filter feeding (Cerastoderma edule). PMID:22952910

  2. Stimulation of microbial nitrogen cycling in aquatic ecosystems by benthic macrofauna: mechanisms and environmental implications

    NASA Astrophysics Data System (ADS)

    Stief, P.

    2013-07-01

    Invertebrate animals that live at the bottom of aquatic ecosystems (i.e., benthic macrofauna) are important mediators between nutrients in the water column and microbes in the benthos. The presence of benthic macrofauna stimulates microbial nutrient dynamics through different types of animal-microbe interactions, which potentially affect the trophic status of aquatic ecosystems. This review contrasts three types of animal-microbe interactions in the benthos of aquatic ecosystems: (i) ecosystem engineering, (ii) grazing, and (iii) symbiosis. Their specific contributions to the turnover of fixed nitrogen (mainly nitrate and ammonium) and the emission of the greenhouse gas nitrous oxide are evaluated. Published data indicate that ecosystem engineering by sediment-burrowing macrofauna stimulates benthic nitrification and denitrification, which together allows fixed nitrogen removal. However, the release of ammonium from sediments often is enhanced even more than the sedimentary uptake of nitrate. Ecosystem engineering by reef-building macrofauna increases nitrogen retention and ammonium concentrations in shallow aquatic ecosystems, but allows organic nitrogen removal through harvesting. Grazing by macrofauna on benthic microbes apparently has small or neutral effects on nitrogen cycling. Animal-microbe symbioses provide abundant and distinct benthic compartments for a multitude of nitrogen-cycle pathways. Recent studies revealed that ecosystem engineering, grazing, and symbioses of benthic macrofauna significantly enhance nitrous oxide emission from shallow aquatic ecosystems. The beneficial effect of benthic macrofauna on fixed nitrogen removal through coupled nitrification-denitrification can thus be offset by the concurrent release of (i) ammonium that stimulates aquatic primary production and (ii) nitrous oxide that contributes to global warming. Overall, benthic macrofauna intensifies the coupling between benthos, pelagial, and atmosphere through enhanced turnover and transport of nitrogen.

  3. Stimulation of microbial nitrogen cycling in aquatic ecosystems by benthic macrofauna: mechanisms and environmental implications

    NASA Astrophysics Data System (ADS)

    Stief, P.

    2013-12-01

    Invertebrate animals that live at the bottom of aquatic ecosystems (i.e., benthic macrofauna) are important mediators between nutrients in the water column and microbes in the benthos. The presence of benthic macrofauna stimulates microbial nutrient dynamics through different types of animal-microbe interactions, which potentially affect the trophic status of aquatic ecosystems. This review contrasts three types of animal-microbe interactions in the benthos of aquatic ecosystems: (i) ecosystem engineering, (ii) grazing, and (iii) symbiosis. Their specific contributions to the turnover of fixed nitrogen (mainly nitrate and ammonium) and the emission of the greenhouse gas nitrous oxide are evaluated. Published data indicate that ecosystem engineering by sediment-burrowing macrofauna stimulates benthic nitrification and denitrification, which together allows fixed nitrogen removal. However, the release of ammonium from sediments is enhanced more strongly than the sedimentary uptake of nitrate. Ecosystem engineering by reef-building macrofauna increases nitrogen retention and ammonium concentrations in shallow aquatic ecosystems, but allows organic nitrogen removal through harvesting. Grazing by macrofauna on benthic microbes apparently has small or neutral effects on nitrogen cycling. Animal-microbe symbioses provide abundant and distinct benthic compartments for a multitude of nitrogen-cycle pathways. Recent studies reveal that ecosystem engineering, grazing, and symbioses of benthic macrofauna significantly enhance nitrous oxide emission from shallow aquatic ecosystems. The beneficial effect of benthic macrofauna on fixed nitrogen removal through coupled nitrification-denitrification can thus be offset by the concurrent release of (i) ammonium that stimulates aquatic primary production and (ii) nitrous oxide that contributes to global warming. Overall, benthic macrofauna intensifies the coupling between benthos, pelagial, and atmosphere through enhanced turnover and transport of nitrogen.

  4. Assessing Water Quality Using Two Taxonomic Levels of Benthic Macroinvertebrate Analysis: Implications for Volunteer Monitors

    Microsoft Academic Search

    Niamh OLeary; A. Thomas Vawter; Linda Plummer Wagenet; Max Pfeffer

    2004-01-01

    With regard to the identification of benthic macroinvertebrates, we evaluated the extent to which family-based information gathered by non-scientist volunteers compared to genus-level analysis by scientists. Volunteer monitors were trained in the techniques of family-level benthic macroinvertebrate analysis by scientists. The volunteers then sampled a local third order stream, identified specimens to the family level, and calculated metrics that led

  5. An estuarine benthic index of biotic integrity (B-IBI) for Chesapeake Bay

    Microsoft Academic Search

    Stephen B. Weisberg; J. Ananda Ranasinghe; Daniel M. Dauer; Linda C. Schaffner; Robert J. Diaz; Jeffrey B. Frithsen

    1997-01-01

    A multimetric benthic index of biotic integrity (B-IBI) was developed using data from five Chesapeake Bay sampling programs\\u000a conducted between 1972 and 1991. Attributes of the index were selected by comparing the response of 17 candidate measures\\u000a of benthic condition (metrics) between a set of minimally affected reference sites and at all other sites for which data were\\u000a available. This

  6. Ocean Stagnation and Anoxia at the Paleocene-Eocene Boundary - Implications for the Benthic Extinction

    Microsoft Academic Search

    A. M. Winguth; C. Winguth

    2010-01-01

    The prominent global hyperthermal at the Paleocene-Eocene boundary (55 Ma), referred to as the Paleocene-Eocene Thermal Maximum (PETM), has been characterized by rapid climatic and geochemical changes, and a major extinction of benthic organisms. In this study, we explore the climate-productivity feedback hypothesis and causes of the extinction of benthic foraminifera by comparing the sedimentary records with results from a

  7. Application of benthic foraminiferal Mg\\/Ca ratios to questions of Cenozoic climate change

    Microsoft Academic Search

    K. Billups; D. P. Schrag

    2003-01-01

    We investigate the evolution of Cenozoic climate and ice volume as evidenced by the oxygen isotopic composition of seawater (?18Osw) derived from benthic foraminiferal Mg\\/Ca ratios to constrain the temperature effect contained in foraminiferal ?18O values. We have constructed two benthic foraminiferal Mg\\/Ca records from intermediate water depth sites (Ocean Drilling Program sites 757 and 689 from the subtropical Indian

  8. Quaternary deep sea temperature histories derived from benthic foraminiferal Mg\\/Ca

    Microsoft Academic Search

    Pamela A. Martin; David W. Lea; Yair Rosenthal; Nicholas J. Shackleton; Michael Sarnthein; Thomas Papenfuss

    2002-01-01

    We have generated benthic foraminiferal Mg\\/Ca records from eastern tropical Atlantic core M16772 (3.9 km) and eastern tropical Pacific core TR163-31P (3.2 km) to assess the potential for using benthic Mg-paleothermometry to reconstruct Quaternary bottom water temperature histories. Variations in Mg\\/Ca records from both the Atlantic and Pacific show a significant correlation with climatic oscillations of the last 330 kyr.

  9. Observations and seasonal periodicity of the benthic algae of Galveston Island, Texas 

    E-print Network

    Lowe, Glenn Curtis

    1975-01-01

    algal growth was found to be limited to winter populations of Phaeophytes and Chlorophytes w1th a rare 1solated Rhodophyte. From an investigation of the benthic algae of the Louisiana coast, Kapraun (1974}, encountered thirty species in monthly field.... , 1969. Field and cultural studies on the seasonal periodicity of growth and reproduction of selected Texas benthic marine algae. Contr. Mar. Sci. Univ. Texas 14: 59-114. 1970. Illustrated guide to the seaweeds and sea grasses in tile vicinity...

  10. Relationship between benthic fluxes and macrophyte cover in a shallow brackish lagoon

    Microsoft Academic Search

    P. Viaroli; M. Bartoli; I. Fumagalli; G. Giordani

    1997-01-01

    The relationship between macrophyte cover and benthic fluxes of oxygen. nutrients and sulphide has been examined in a shallow\\u000a fishpond with a nearly homogeneous meadow ofRuppia cirrhosa (Pelagna) Grande (Bassin d'Arcachon. western France). In 1993 and 1994, benthic fluxes were treasured in early and late summer.\\u000a These periods were selected to represent the production and decay phases ofRuppia in order

  11. Salinity and temperature effects on photosynthesis and organic carbon release rates by selected benthic macroalgae

    SciTech Connect

    Yarish, C.; Heller, M.

    1983-09-01

    Estuarine benthic macroalgae are excellent producers of new carbonaceous material through their high rates of photosynthesis. Under some circumstances, this organic carbon is liberated into the aquatic environment in dissolved form while the plant is actively photosynthesizing. This project established a protocol for examining the effects of different combinations of salinity, temperature, and emergence/submergence regimes, determined the effects of antibiotics on the photosynthetic rate, and the extent to which these factors effect liberation of organics by selected estuarine benthic macroalgae.

  12. 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 summer than in spring, in turn suggesting an important role of macrofauna bioturbation and filter feeding (Cerastoderma edule). PMID:22952910

  13. 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. [National Biological Service, Columbia, MO (United States)

    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.

  14. Benthic foraminiferal faunal and isotopic changes as recorded in Holocene sediments of the northwest Indian Ocean

    NASA Astrophysics Data System (ADS)

    Gupta, Anil K.; Das, Moumita; Clemens, Steven C.; Mukherjee, Baidehi

    2008-06-01

    Historically, the Holocene has been considered an interval of relatively stable climate. However, recent studies from the northern Arabian Sea (Netherlands Indian Ocean Program 905) suggested high-amplitude climate shifts in the early and middle Holocene based on faunal and benthic isotopic proxy records. We examined benthic foraminiferal faunal and stable isotopic data from Ocean Drilling Program (ODP) Site 723 and total organic carbon data from ODP Site 724, Oman Margin (808 and 593 m water depths, respectively). At Site 723 the mid-Holocene shift in ?18O values of infaunal benthic species Uvigerina peregrina (1.4‰) is 3 times larger than that of epifaunal benthic species Cibicides kullenbergi recorded at Site NIOP 905 off Somalia. However, none of the five other benthic species we measured at Hole 723A exhibits such a shift in ?18O. We speculate that the late Holocene ?18O decrease in U. peregrina represents species-specific changes in ecological habitat or food preference in response to changes in surface and deep ocean circulation. While the stable isotopic data do not appear to indicate a middle Holocene climatic shift, our total organic carbon and benthic faunal assemblage data do indicate that the early Holocene deep Arabian Sea was influenced by increased ventilation perhaps by North Atlantic Deep Water and/or Circumpolar Deep Water incursions into the Indian Ocean, leading to remineralization of organic matter and a relatively weak early Holocene oxygen minimum zone in the northwest Arabian Sea in spite of strong summer monsoon circulation.

  15. An oceanographic observation of the 2013 Mt.Etna pyroclastic fallout in the Ionian deep seafloor: multiparametric investigation through benthic observatory

    NASA Astrophysics Data System (ADS)

    Lo Bue, Nadia; Sgroi, Tiziana; Giovanetti, Gabriele; Marinaro, Giuditta; Embriaco, Davide; Beranzoli, Laura; Favali, Paolo

    2015-04-01

    Very large amounts of volcanic ash are released into the atmosphere during eruptive events. Taken over the atmospheric forcing tephra may be carried over great distances remaining in suspension for a long time. Nevertheless, the wind is not the only responsible for transport and dispersion of volcanic particles, but, especially in volcanic areas close to the coast, the ash fallout in marine areas plays an interesting role in the sedimentation processes affecting the benthic environments. During the Mt. Etna eruptive events of 2013, the volcanic ash fallout occurred in the Western Ionian Sea deep layers was recorded by an oceanographic sensor mounted on the cabled benthic node NEMO-SN1. The seafloor observatory was deployed in the framework of the European Research Infrastructure EMSO (European Multidisciplinary Seafloor and water-column Observatory) at a depth of 2100 m, about 25 km off-shore Eastern Sicily. The presence of a specific Acoustic Doppler Current Profiler (ADCP) able to monitor currents and direction of water particles in a depth range of about 30-50m above the seafloor, allowed to watch interesting episodes of suspended matter at the deep layers in correspondence with the pyroclastic activity which affected the ESE sector of the Etna volcano. The analysis of the acoustic backscattering signal of this sensor, combined with seismological and oceanographic data recorded by the benthic station, allowed to carry out a multidisciplinary study about the possible interaction between the Mt. Etna eruptive activity and the local oceanographic dynamic. This approach leads to consider that sedimentation processes of volcanic ash occurred, allowing to investigate on the very fast horizontal and vertical transport observed. Moreover, the surprising sedimentation rate recorded, probably results from intense aggregation and alteration processes affecting the ash particles in seawater. The importance of the presence of a multidisciplinary benthic observatory in sensible areas, such as the Western Ionian Sea, is confirmed by the possibility to record and monitor important processes otherwise unexplored, and also by the opportunity to carry out multidisciplinary studies indispensable to explain the observed processes.

  16. A deep-sea sediment transport storm

    NASA Astrophysics Data System (ADS)

    Gross, Thomas F.; Williams, A. J.; Newell, A. R. M.

    1988-02-01

    Photographs taken of the sea bottom since the 1960s suggest that sediments at great depth may be actively resuspended and redistributed1. Further, it has been suspected that active resus-pension/transport may be required to maintain elevated concentrations of particles in deep-sea nepheloid layers. But currents with sufficient energy to erode the bottom, and to maintain the particles in suspension, have not been observed concurrently with large concentrations of particles in the deep nepheloid layer2-4. The high-energy benthic boundary-layer experiment (HEBBLE) was designed to test the hypothesis that bed modifications can result from local erosion and deposition as modelled by simple one-dimensional local forcing mechanics5. We observed several 'storms' of high kinetic energy and near-bed flow associated with large concentrations of suspended sediment during the year-long deployments of moored instruments at the HEBBLE study site. These observations, at 4,880 m off the Nova Scotian Rise in the north-west Atlantic, indicate that large episodic events may suspend bottom sediments in areas well removed from coastal and shelf sources.

  17. 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 increase in trace metal concentration. The ecological changes may have been caused by increased productivity of diatoms resulting from beginning anthropogenic eutrophication. From the middle 1960's on, absolute foraminiferal abundance decreased and Ammonia beccarii, formerly absent or rare, became common to dominant in WLIS75GGC1; in B1GGC1 a similar but less severe change started in the 1970's. The increase in relative abundance of A. beccarii could have been caused by hypoxia (possibly in conjunction with rising bottom water temperatures), but both Ammonia and Elphidium species survive hypoxia in the laboratory. We suggest that high N/Si resulting from strong eutrophication might favor primary producers other than diatoms (e.g., dinoflagellates, cyanobacteria), making E. excavatum less competitive. The LIS coastal ecosystem thus changed significantly with the enhanced nutrient input associated with human population growth in the middle 1800's, and again with more severe eutrophication over the last few decades.

  18. Spatial and Temporal Variability of Benthic Oxygen Demand and Nutrient Regeneration in an Anthropogenically Impacted New England Estuary

    Microsoft Academic Search

    Robinson W. Fulweiler; Scott W. Nixon; Betty A. Buckley

    2010-01-01

    Strong benthic–pelagic coupling is an important characteristic of shallow coastal marine ecosystems. Building upon a rich\\u000a history of benthic metabolism data, we measured oxygen uptake and nutrient fluxes across the sediment–water interface along\\u000a a gradient of water column primary production in Narragansett Bay, RI (USA). Despite the strong gradients seen in water column\\u000a production, sediment oxygen demand (SOD) and benthic

  19. A Cenozoic seawater Sr\\/Ca record from benthic foraminiferal calcite and its application in determining global weathering fluxes

    Microsoft Academic Search

    C. H. Lear; H. Elderfield; P. A. Wilson

    2003-01-01

    A Cenozoic multi-species record of benthic foraminiferal calcite Sr\\/Ca has been produced and is corrected for inter-specific offsets (typically less than 0.3 mmol\\/mol) and for the linear relationship between decreasing benthic foraminiferal Sr\\/Ca and increasing water depth. The water depth correction, determined from Holocene, Late Glacial Maximum and Eocene paleowater-depth transects, is ?0.1 mmol\\/mol\\/km. The corrected Cenozoic benthic foraminiferal Sr\\/Ca

  20. Perturbation at the sea floor during the Paleocene–Eocene Thermal Maximum: Evidence from benthic foraminifera at Contessa Road, Italy

    Microsoft Academic Search

    Luca Giusberti; Rodolfo Coccioni; Mario Sprovieri; Fabio Tateo

    2009-01-01

    Detailed analyses of the benthic foraminiferal assemblages extracted with the cold acetolyse method together with high resolution geochemical and mineralogical investigations across the Paleocene\\/Eocene (P\\/E) boundary of the classical succession at Contessa Road (western Tethys), allowed to recognize and document the Paleocene–Eocene Thermal Maximum (PETM) interval, the position of the Benthic Extinction Event (BEE) and the early recovery of benthic

  1. The effects of beach nourishment on benthic invertebrates in eastern Australia: impacts and variable recovery.

    PubMed

    Schlacher, Thomas A; Noriega, Rocio; Jones, Alan; Dye, Theresa

    2012-10-01

    Beach erosion is likely to accelerate, driven by predicted consequences of climate change and coastal development. Erosion is increasingly combated by beach nourishment, adding sand to eroding shores. Because a range of engineering techniques exists to nourish beaches, and because these techniques differ in their environmental effects, assessments of ecological impacts need to be tailored and specific. Here we report on impacts and recovery of benthic invertebrates impacted by beach nourishment operations undertaken at Palm Beach (SE Queensland, Australia). Assessments are made based on a beyond-BACI design, where samples were taken once before nourishment and twice afterwards at the impact and two control sites. Because almost all of the sand was deposited on the upper beach and later moved with bulldozers down-shore, we specifically examined whether the effects of nourishment varied at different heights of the beach-a little-studied question which has management implications. Impacts on the fauna were massive on the upper and middle levels of the beach: samples collected two days after the conclusion of nourishment were entirely devoid of all invertebrate life ('azoic'), whereas weaker effects of nourishment were detectable on the lower shore. Recovery after five months also varied between shore levels. The sediment of the upper level near the dunes remained azoic, the fauna of the middle shore had recovered partially, and the lower level had recovered in most respects. These findings indicate that the height and position of sand placement are important. For example, rather than depositing fill sand on the intertidal beach, it could be placed in the shallow subtidal zone, followed by slow up-shore accretion driven by hydrodynamic forces. Alternatively, techniques that spread the fill sand in thin layers (to minimize mortality by burial) and leave unfilled intertidal refuge islands (to provide colonists) may minimize the ecological impacts of beach nourishment. PMID:22878101

  2. 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.

  3. Coupling between phytodetritus deposition and the small-sized benthic biota in the deep Arabian Sea: analyses of biogenic sediment compounds

    NASA Astrophysics Data System (ADS)

    Pfannkuche, Olaf; Sommer, Stefan; Kähler, Anja

    As part of the large-scale, interdisciplinary deep-sea study "BIGSET", the relationship between the monsoon-induced regional and temporal variability of POC deposition and the small-sized benthic community was investigated at several sites 2316-4420 m deep in the Arabian Sea during four cruises between 1995 and 1998. Vertical and horizontal distribution patterns of chloroplastic pigments (a measure of phytodetritus deposition), readily soluble protein and activity, and biomass parameters of the small-sized benthic community (Electron Transport System Activity (ETSA); bacterial ectoenzymatic activity (FDA turnover) and DNA concentrations) were measured concurrently with the vertical fluxes of POC and chloroplastic pigments. Sediment chlorophyll a (chl. a) profiles were used to calculate chl. a flux rates and to estimate POC flux across the sediment water interface using two different transport reaction models. These estimates were compared with corresponding flux rates determined in sediment traps. Regional variability of primary productivity and POC deposition at the deep-sea floor creates a trophic gradient in the Arabian Basin from the NW to the SE, which is primarily related to the activity of monsoon winds and processes associated with the topography of the Arabian Basin and the vicinity of land masses. Inventories of sediment chloroplastic pigments closely corresponded to this trophic gradient. For ETSA, FDA and DNA, however, no clear coupling was found, although stations WAST (western Arabian Sea) and NAST (northern Arabian Sea) were characterised by high concentrations and activities. These parameters exhibited high spatial and temporal variability, making it impossible to recognise clear mechanisms controlling temporal and spatial community patterns of the small-sized benthic biota. Nevertheless, the entire Arabian Basin was recognised as being affected by monsoonal activity. Comparison of two different transport reaction models indicates that labile chl. a buried in deeper sediment layers may escape rapid degradation in Arabian deep-sea sediments.

  4. Mid-depth oxygen drawdown during Heinrich events: evidence from benthic foraminiferal community structure, trace-fossil tiering, and benthic ? 13C at the Portuguese Margin

    Microsoft Academic Search

    J. H. Baas; J. Schönfeld; R. Zahn

    1998-01-01

    The distribution of trace fossils and benthic foraminiferal assemblages in two sediment cores from 2160 m water depth at the northern and 1100 m at the southern Portuguese continental margin was used to reconstruct the bottom-water oxygenation during the last 40 ka. Emphasis was given to the Heinrich events, during which enhanced meltwater flux associated with the iceberg surges reduced

  5. Relationship between bifenthrin sediment toxic units and benthic community metrics in urban California streams.

    PubMed

    Hall, Lenwood W; Anderson, Ronald D

    2013-08-01

    The objective of this study was to use ecologically relevant field measurements for determining the relationship between bifenthrin sediment toxic units (TUs) (environmental concentrations/Hyalella acute LC50 value) and 15 benthic metrics in four urban California streams sampled from 2006 to 2011. Data from the following four California streams were used in the analysis: Kirker Creek (2006, 2007), Pleasant Grove Creek (2006, 2007, and 2008), Arcade Creek (2009, 2010, and 2011), and Salinas streams (2009, 2010, and 2011). The results from univariate analysis of benthic metrics versus bifenthrin TU calculations for the four California streams with multiple-year datasets combined by stream showed that there were either nonsignificant relationships or lack of metric data for 93 % of cases. For 7 % of the data (4 cases) where significant relationships were reported between benthic metrics and bifenthrin TUs, these relationships were ecologically meaningful. Three of these significant direct relationships were an expression of tolerant benthic taxa (either % tolerant taxa or tolerance values, which are similar metrics), which would be expected to increase in a stressed environment. These direct significant tolerance relationships were reported for Kirker Creek, Pleasant Grove Creek, and Arcade Creek. The fourth significant relationship was an inverse relationship between taxa richness and bifenthrin TUs for the 3-year Pleasant Grove Creek dataset. In summary, only a small percent of the benthic metric × bifenthrin TU relationships were significant for the four California streams. Therefore, the general summary conclusion from this analysis is that there is no strong case for showing consistent meaningful relationships between various benthic metrics used to characterize the status of benthic communities and bifenthrin TUs for these four California streams. PMID:23625138

  6. 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 ?13C 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 ?15N 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.

  7. 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.

  8. Effects of chemical disturbances on intertidal benthic assemblages.

    PubMed

    Mayer-Pinto, Mariana; Ignacio, Barbara Lage

    2015-02-15

    Contamination is a particular harmful type of chemical disturbance and predicting their effects on natural systems is very complex. Effects of disturbances vary in space and time and depend, among other things, on the type and age of organisms, the habitat being studied and the complex interactions occurring in the systems. Most impact analyses of contaminants are however still done with limited number of selected organisms under laboratory conditions. Manipulative experiments done in situ are important to measure ecologically relevant responses of contaminant effects on marine systems. Ecological approaches on contamination studies, accounting for interactions among species and the environment are essential to understand how such disturbances affect systems. We evaluated the effects of bleach and permethrin, two common and pervasive contaminants, on intertidal benthic assemblages in two different successional stages, mature and young. There were no impacts on the overall structure of assemblages, regardless of their age. The lack of effects on the structure of assemblages might be due to the intrinsic characteristic of the habitat studied, which provide few sinks for contaminants, as well as the inherent features of the organisms themselves. Bleach did cause, however, a decrease in the abundance of limpets, which can have further consequences to these systems. This study shows the importance of studies on chemical disturbances done under relevant natural scenarios and that efficient management policies of natural systems will only achieve successful responses with properly designed experiments under natural conditions. PMID:25460934

  9. 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

  10. Heavy metals of inshore benthic invertebrates from the Barents Sea.

    PubMed

    Zauke, G-P; Clason, B; Savinov, V M; Savinova, T

    2003-05-01

    To assess metals in biota of the Barents Sea, information is presented on concentrations of Cu, Cd, Ni, Pb and Zn in the marine inshore benthic invertebrates Gammarus oceanicus, Littorina rudis, Nucella lapillus, Mytilus edulis and Arenicola marina collected in summer 1994. For geographical comparisons, the metal content to body size relationship was taken into account due to the different body sizes found at the localities investigated. In general, our data provide further evidence for the cadmium anomaly in invertebrates from polar waters which has been frequently discussed in the literature, with Cd concentrations reaching 1 mg x kg(-1) dry wt in G. oceanicus, 7 mg x kg(-1) in L. rudis and 24 mg x kg(-1) in N. lapillus. In contrast, our results obtained for Cd in M. edulis and A. marina are largely within a world-wide reported range (1-2 and 0.2-0.9 mg x kg(-1), respectively). Although some severe Ni emissions in the Kola region (Russia) mainly from nickel smelters have been reported, we do not find indications of an enhanced Ni availability in the marine biota studied compared to other areas PMID:12699921

  11. 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. PMID:25560929

  12. Comparability of Benthic Macroinvertebrate Sampling Methods in Montana Streams

    NASA Astrophysics Data System (ADS)

    Feldman, D. L.; Laidlaw, T.; Jessup, B.; Stribling, J.; Stagliano, D.; Bollman, W.

    2005-05-01

    There are several benthic macroinvertebrate sampling techniques currently being used by the Montana Department of Environmental Quality (DEQ) that evaluate instream water resource quality. A traveling kick or a jab with a D-frame net collects most samples. DEQ monitors a smaller proportion of sites using Hess Samplers. Also used in the state are the sampling methods of the U.S. EPA Environmental Monitoring and Assessment Program (EMAP) and Regional Environmental Monitoring and Assessment Program (REMAP). Both EMAP and REMAP use a D-frame net, distributing sampling effort throughout the target reach along a series of transects. The purpose of this study is to evaluate the effects of these four different sampling techniques on the samples gathered, in particular, on taxonomic diversity and metric values. This evaluation will help DEQ accomplish its ultimate goal: to implement consistent statewide sampling protocols. We developed a suite of both quantitative and qualitative performance characteristics (precision, accuracy, bias) for each of the methods, and directly compared them among the protocols. The level of comparability among methods was characterized and the acceptability of each method for use by Montana DEQ was determined.

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

    NASA Astrophysics Data System (ADS)

    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.

  14. Benthic Bacterial and Fungal Productivity and Carbon Turnover in a Freshwater Marsh

    PubMed Central

    Buesing, Nanna; Gessner, Mark O.

    2006-01-01

    Heterotrophic bacteria and fungi are widely recognized as crucial mediators of carbon, nutrient, and energy flow in ecosystems, yet information on their total annual production in benthic habitats is lacking. To assess the significance of annual microbial production in a structurally complex system, we measured production rates of bacteria and fungi over an annual cycle in four aerobic habitats of a littoral freshwater marsh. Production rates of fungi in plant litter were substantial (0.2 to 2.4 mg C g?1 C) but were clearly outweighed by those of bacteria (2.6 to 18.8 mg C g?1 C) throughout the year. This indicates that bacteria represent the most actively growing microorganisms on marsh plant litter in submerged conditions, a finding that contrasts strikingly with results from both standing dead shoots of marsh plants and submerged plant litter decaying in streams. Concomitant measurements of microbial respiration (1.5 to 15.3 mg C-CO2 g?1 of plant litter C day?1) point to high microbial growth efficiencies on the plant litter, averaging 45.5%. The submerged plant litter layer together with the thin aerobic sediment layer underneath (average depth of 5 mm) contributed the bulk of microbial production per square meter of marsh surface (99%), whereas bacterial production in the marsh water column and epiphytic biofilms was negligible. The magnitude of the combined production in these compartments (?1,490 g C m?2 year?1) highlights the importance of carbon flows through microbial biomass, to the extent that even massive primary productivity of the marsh plants (603 g C m?2 year?1) and subsidiary carbon sources (?330 g C m?2 year?1) were insufficient to meet the microbial carbon demand. These findings suggest that littoral freshwater marshes are genuine hot spots of aerobic microbial carbon transformations, which may act as net organic carbon importers from adjacent systems and, in turn, emit large amounts of CO2 (here, ?870 g C m?2 year?1) into the atmosphere. PMID:16391096

  15. 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 oxygen uptake rates in the warm, productive season. During the summer season, oxygen uptake is significantly higher on silty or muddy, organic-rich sediments than on fine sands or gravel. Epi- and infauna, however, increase the benthic oxygen uptake and nutrient fluxes apparently irrespective of the grain size of the underlying lithogenic sedimentary particles or the water depth. These first results originate from the projects "NOAH - North Sea: Observation and Assessment of Habitats" and "WiMo - Wissenschaftliche Monitoringkonzepte für die Deutsche Bucht / Scientific monitoring concepts for the German Bight".

  16. Long-term monitoring of the sedimentary processes in the central part of Sagami Bay, Japan: rationale, logistics and overview of results

    NASA Astrophysics Data System (ADS)

    Kitazato, Hiroshi; Nakatsuka, Takeshi; Shimanaga, Motohiro; Kanda, Jota; Soh, Wonn; Kato, Yoshihisa; Okada, Yoshihiro; Yamaoka, Akio; Masuzawa, Toshiyuki; Suzuki, Koji; Shirayama, Yoshihisa

    2003-04-01

    Deep-sea benthic ecosystems are mainly sustained by sinking organic materials that are produced in the euphotic zone. “Benthic-pelagic coupling” is the key to understanding both material cycles and benthic ecology in deep-sea environments, in particular in topographically flat open oceanic settings. However, it remains unclear whether “benthic-pelagic coupling” exists in eutrophic deep-sea environments at the ocean margins where areas of undulating and steep bottom topography are partly closely surrounded by land. Land-locked deep-sea settings may be characterized by different particle behaviors both in the water column and in relation to submarine topography. Mechanisms of particle accumulation may be different from those found in open ocean sedimentary systems. An interdisciplinary programme, “Project Sagami”, was carried out to understand seasonal carbon cycling in a eutrophic deep-sea environment (Sagami Bay) with steep bottom topography along the western margin of the Pacific, off central Japan. We collected data from ocean color photographs obtained using a sea observation satellite, surface water samples, hydrographic casts with turbidity sensor, sediment trap moorings and multiple core samplings at a permanent station in the central part of Sagami Bay between 1997 and 1998. Bottom nepheloid layers were also observed in video images recorded at a real-time, sea-floor observatory off Hatsushima in Sagami Bay. Distinct spring blooms were observed during mid-February through May in 1997. Mass flux deposited in sediment traps did not show a distinct spring bloom signal because of the influence of resuspended materials. However, dense clouds of suspended particles were observed only in the spring in the benthic nepheloid layer. This phenomenon corresponds well to the increased deposition of phytodetritus after the spring bloom. A phytodetrital layer started to form on the sediment surface about two weeks after the start of the spring bloom. Chlorophyll- a was detected in the top 2 cm of the sediment only when a phytodetritus layer was present. Protozoan and metazoan meiobenthos increased in density after phytodetritus deposition. Thus, “benthic-pelagic coupling” was certainly observed even in a marginal ocean environment with undulated bottom topography. Seasonal changes in features of the sediment-water interface were also documented.

  17. 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)

  18. 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.

  19. 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. PMID:12620013

  20. Multispecies Record of Benthic Foraminiferal Shell Weight in Santa Barbara Basin: A Deglacial Environmental Record

    NASA Astrophysics Data System (ADS)

    Davis, K. V.; Hill, T. M.; Moffitt, S. E.; Downing, S.

    2012-12-01

    There exists increasing interest in resolving the effect of environmental parameters on foraminiferal test weight. We utilize a high-resolution core, MV0811-15JC (34°36.930' N, 119°12.920' W; 418m water depth; 3-15 ka; sedimentation rate ~100cm/ka) from the Santa Barbara Basin (SBB) to examine a multispecies record of benthic foraminiferal weight and test wall thickness. We compare these findings to records of benthic ecosystem, oxygenation and ?18O change during and since the last deglaciation. Ongoing work in SBB has characterized drastic changes in benthic communities over the past 15 kyr in response to climate and dissolved oxygen concentrations. Records of the average test weight in the >250 ?m size fraction of Uvigerina peregrina covary with changes in the benthic community in response to oxygenation events and may represent a record of average maximum growth size. Average test weight, constrained by a narrow size fraction (within < 55 ?m difference in mesh size), is sometimes treated alone or with additional size correction as a proxy for test wall thickness. Narrow fraction test weights show significantly less variability in both Uvigerina peregrina and Bolivinia argentea between samples. We further analyze average test wall thickness in these samples, to develop an understanding of controls on shell weight and ongoing work seeks, to identify ideal benthic target species and to best understand shell weight as a proxy for carbonate ion (pH) of seawater.

  1. Variation of a benthic heterotrophic bacteria community with different respiratory metabolisms in Coyuca de Benítez coastal lagoon (Guerrero, Mexico).

    PubMed

    Ferrara-Guerrero, María Jesús; Castellanos-Páez, María Elena; Garza-Mouriño, Gabriela

    2007-03-01

    The fluctuations of the number, biomass and composition of the heterotrophic community were studied daily for two days, according to depth, pH, Eh, O2 and organic carbon concentration within a zone of the canal between the Coyuca de Benitez lagoon (Guerrero, Mexico) and the coastal waters. At the three moments of the day studied (6 am, 2 pm and 10 pm), the oxygen concentrations in the overlying water and in the superficial sediment layer were near air-saturation in the diurnal samplings (582 microM at 6 am and 665 microM at 2 pm), and sub-satured during the night (158 microM). In the sediments, the models of vertical distribution of Eh and organic carbon distributions were very irregular due to the bio-perturbation of the benthic, meio- and macrofauna, whose activity allows the superficial organic carbon to migrate towards sediment deeper layers. Vertical distribution of the different viable bacteria populations seems to be related to the hydrodynamic patterns of the communicating canal and sediments heterogeneity. In the sediment column, the heterotrophic bacteria total number varied from 6.8 to 20.3 x 108 cells cm(-3). The highest heterotrophic bacterial biomass values were encountered during the diurnal samplings (39.2 microgC.l(-1) at 6 am and 34.4 microgC.(l(-1) at 2 pm) and the lowest during the night (9.7 microgC.l(-1). The fluctuations of viable heterotrophic bacteria populations with different respiratory metabolisms (aerobic, microaerophilic and anaerobic) can be explained by the existence of suboxic microniches that appear when particles of sediment are resuspended due to the water circulation and the benthic infauna excavating activity, that allows the supernatant water oxygen to penetrate through its galleries towards deeper sediment zones. The statistical analysis (Multiple lineal regression model r2 > or = 0.5) showed that the on the whole, the hydrological parameters are not influence over the bacterial number and bacterial biomass distribution (r2 < or = 0.5), Nevertheless, the variations of the heterotrophic bacteria community observed in the two days sampling, seem to be governed (with F-values of 0.6 to 0.9) by the irregular flows of bio-available organic material and the sediment porosity. PMID:18457123

  2. Benthic foraminifera from polluted marine environment of Sulaibikhat Bay (Kuwait).

    PubMed

    Al-Zamel, A Z; Al-Sarawi, M A; Khader, S R; Al-Rifaiy, I A

    2009-02-01

    Quantitative analyses of recent benthic foraminiferal assemblages (living and dead) were carried out on the surface sediments of Sulaibikhat Bay. Marked contrast in foraminiferal assemblages between the shallow tidal mudflats and the deep tidal channel and their relation to the extent of pollution were observed. Cluster analysis of quantitative data on the distribution of foraminiferal tests revealed three assemblages that depend mainly on the intensity of pollution; (1) a highly polluted tidal flat assemblage, (2) normal (or less polluted) mud flat assemblage and, (3) tidal channel and subtidal assemblage. The highly polluted assemblage characterized by a drop in species densities (< 100 tests/20 cm(3) sediment) but with high average diversity (5.8 Yule-Simpson Index). The microfauna of the less polluted flat displays relatively lower diversity (4.6) but high density of tests (47.2% of the total picked tests). The most abundant species of this assemblage is Ammonia tepida, displays its maximum density in this assemblage. Ammonia tepida drops in density from 17.12% to 3.07% in the polluted assemblage. Tidal channel foraminiferal assemblages should normally display lower diversities than those of tidal flats, because tidal current in the channels tend to wash away most nutrient materials. However, this is not the case of the present study area which could be due to environmental setting of the Sulaibikhat Bay in which tidal currents bring in exceptionally high amounts of nutrients from Shatt Al-Arab Estuary and in which the tidal flats are strongly and adversely polluted. PMID:18389379

  3. 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 with artificial or heavily modified water bodies. PMID:23288597

  4. 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...

  5. Sampling Benthic Macroinvertebrates in a Large FloodPlain River: Considerations of Study Design, Sample Size, and Cost

    Microsoft Academic Search

    Lynn A. Bartsch; William B. Richardson; Teresa J. Naimo

    1998-01-01

    Estimation of benthic macroinvertebrate populations over large spatial scales is difficult due to the high variability in abundance and the cost of sample processing and taxonomic analysis. To determine a cost-effective, statistically powerful sample design, we conducted an exploratory study of the spatial variation of benthic macroinvertebrates in a 37 km reach of the Upper Mississippi River. We sampled benthos

  6. Ecological Responses to Hydrogeomorphic Fluctuations in a Sand Bed Prairie River: River Complexity, Habitat Availability, and Benthic Invertebrates

    E-print Network

    O'Neill, Brian James

    2010-04-02

    Ecological Responses to Hydrogeomorphic Fluctuations in a Sand Bed Prairie River: River Complexity, Habitat Availability, and Benthic Invertebrates By Brian J. O’Neill Submitted to the graduate degree program in Ecology and Evolutionary..., Habitat Availability, and Benthic Invertebrates Committee: _____________________________ Chairperson Date Approved_____________________ 3 Abstract Rivers...

  7. 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...

  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 ? 13C and ? 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 ? 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. Benthic hydroids associated with volcanic structures from Bransfield Strait (Antarctica) collected by the Spanish Antarctic expedition GEBRAP96

    Microsoft Academic Search

    A. L. Peña Cantero; F. Ramil

    2006-01-01

    During the Spanish Antarctic expedition GEBRAP96 a survey to study the benthic fauna associated with deep volcanic structures in the Bransfield Strait was carried out. Amongst the benthic samples, a small collection of hydroids was gathered. A total of 10 species, most of them Leptothecata, was recorded; only two species of anthoathecates were present. Kirchenpaueriidae and Sertulariidae were the dominant

  10. BENTHIC AND PLANKTONIC ALGAL COMMUNITIES IN A HIGH ARCTIC LAKE: PIGMENT STRUCTURE AND CONTRASTING RESPONSES TO NUTRIENT

    E-print Network

    Vincent, Warwick F.

    BENTHIC AND PLANKTONIC ALGAL COMMUNITIES IN A HIGH ARCTIC LAKE: PIGMENT STRUCTURE AND CONTRASTING´zina and Vincent 1997). The classic work on Char Lake in the Canadian High Arctic drew attention to its structure and composition of phytoplankton and benthic cyano- bacterial mats in Ward Hunt Lake

  11. Recruitment of coastal planktonic diatoms from benthic versus pelagic cells: Variations in bloom development and species composition

    Microsoft Academic Search

    Melissa R. McQuoid; Anna Godhe

    2004-01-01

    Although phytoplankton blooms are major events in aquatic systems, the importance of benthic resting stages in seeding planktonic blooms is still unclear. Using microcosms, we tested the influence of benthic versus planktonic inocula on the development and taxonomic composition of diatom communities in a temperate fjord. Experiments in early spring 2002, fall 2002, and late spring 2003 showed that the

  12. Biomass estimation across the benthic community in polluted freshwater sediment—A promising endpoint in microcosm studies?

    Microsoft Academic Search

    Michael Faupel; Kai Ristau; Walter Traunspurger

    2011-01-01

    With respect to the ecological relevance of endpoints, biomass as an endpoint might be promising regarding ecotoxicological assessments of benthic communities. In a freshwater microcosm study the effect of two cadmium (Cd) concentrations (50 and 400mgCdkg?1 dw) on biomass and abundance of a benthic community were investigated over a period of seven months. Specifically, the sensitivity of both endpoints in

  13. Habitat Availability and Benthic Invertebrate Population Changes Following Alum Treatment and Hypolimnetic Oxygenation in Newman Lake, Washington

    Microsoft Academic Search

    Jeffrey L. Doke; William H. Funk; Steve T. J. Juul; Barry C. Moore

    1995-01-01

    Changes in benthic macroinvertebrate population density and diversity were studied in a mesotrophic lake with seasonal hypoxia\\/anoxia prior to and following aluminum sulfate (alum) treatment and hypolimnetic oxygenation. Historically, low oxygen concentrations created a benthic zone with reduced fish predation pressures which allowed chaoborids to flourish. Population densities of chironomids and oligochaetes were suppressed by prolonged periods of summer anoxia

  14. Comparison of seasonal dynamics of the essential PUFA contents in benthic invertebrates and grayling Thymallus arcticus in the Yenisei river

    Microsoft Academic Search

    N. N. Sushchik; M. I. Gladyshev; G. S. Kalachova; O. N. Makhutova; A. V. Ageev

    2006-01-01

    Seasonal dynamics of contents of essential polyunsaturated fatty acids (PUFA) in dominant groups of benthic invertebrates: gammarids (Gammaridae, Amphipoda), oligochaetes (Oligochaeta), chironomid larvae (Chironomidae, Diptera) and caddisfly larvae (Trichoptera), and dominant benthivorous fish, Siberian grayling Thymallus arcticus, have been studied in ecosystem of the large Siberian river. During the year of the study most benthic invertebrate taxa showed significant variations

  15. Uptake of organic xenobiotics by benthic invertebrates from sediment contaminated by the pulp and paper industry.

    PubMed

    Meriläinen, Päivi; Oikari, Aimo

    2008-03-01

    Uptake of pulp and paper mill-derived pollutants by benthic invertebrates from sediment in Southern Lake Saimaa, eastern Finland, was studied. Two groups of benthic invertebrates (Diptera and Oligochaeta) were analyzed for their concentrations of resin acids (RAs), chlorophenolics (CPs) and beta-sitosterol. The samples were collected 1 and 3km downstream from the mill. In laboratory experiments Chironomus plumosus (a dipteran) and Lumbriculus variegatus (oligochaete) were exposed for 14d to sediments collected from the same locations. The concentrations of RAs, CPs and beta-sitosterol were higher in the areas downstream from the mill than those in the upstream reference area in both the feral and laboratory-exposed animals. Examination of the possible conjugation of contaminants revealed hydrolyzable fractions of RAs in Diptera, C. plumosus and L. variegatus. The results indicate both the bioavailability uptake of contaminants and uptake by benthic fauna when exposed to pulp and paper mill-contaminated sediment. PMID:17988707

  16. Spatio-Temporal Variability in Benthic ?13c Across the Last Deglaciation

    NASA Astrophysics Data System (ADS)

    Peterson, C. D.; Lisiecki, L. E.

    2014-12-01

    Ocean circulation changes during the last glacial termination played an important role in atmospheric CO2 rise and millennial-scale climate change. These circulation changes can be reconstructed using benthic ?13C from Cibicidoides wuellerstorfi as a proxy for deep water geometry and ventilation. Here we analyze spatio-temporal variability in benthic ?13C across the deglaciation using data from ~90 core locations (70 from the Atlantic). We reconstruct patterns of ?13C change in 1-kyr timeslices from 2-24 kyr ago. Principal component analysis reveals the primary modes of deep water circulation change and their links to millennial-scale climate change. 3D visualization tools assist in the interpretation of benthic ?13C spatial patterns with respect to complex basin geometry (e.g. East vs. West Atlantic). Additionally, we present regional ?13C stacks that improve the signal-to-noise ratio for estimates of the mean ?13C change in different water masses through time.

  17. Benthic foraminiferal assemblages as pollution proxies in the northern coast of Gabes Gulf, Tunisia.

    PubMed

    Aloulou, Fatma; EllEuch, Boubaker; Kallel, Monem

    2012-01-01

    A study of chemical and sedimentological parameters integrated with benthic foraminifera investigation was conducted along the northern coast of Gabes Gulf. Thirty-two samples were studied and a total of 68 benthic foraminiferal species were identified. Heavy metals enrichment factors and total hydrocarbon concentrations showed both metal and petrogenic pollution related mainly to phosphogypsum, sewage, and fishing activities. Statistical analysis (bivariate correlation and hierarchical cluster analysis) show a possible control of these pollutants on density, diversity, as well as the taxonomic composition of the benthic foraminiferal assemblages. The extent to which the population was found less dense and less diversified corresponded to the degree to which the sediment was contaminated. In these contaminated sites, an increase in relative abundance of opportunistic species such Ammonia tepida and Haynesina germanica was found. Far from pollution, foraminiferal assemblages are dominated by species characteristic of Mediterranean shallow water (Ammonia beccarii, Ammonia parkinsoniana, Elphidium crispum, Elphidium williamsoni, Elphidium advenum, Peneroplis planatus, Peneroplis pertesus). PMID:21476104

  18. Shifts in Benthic Algal Community Structure and Function Following the Appearance of Zebra Mussels ( Dreissena polymorpha) in Saginaw Bay, Lake Huron

    Microsoft Academic Search

    Rex L. Lowe; Robert W. Pillsbury

    1995-01-01

    Zebra mussel, Dreissena polymorpha (Pallas), proliferation in Saginaw Bay, Lake Huron is associated with increased water clarity and increased light levels on benthic substrata in the littoral zone. We hypothesized that the filtering activities of Dreissena and associated increases in light penetration should affect the structure and function of benthic algae in the bay. Monthly quantitative benthic algal samples were

  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 the amount of overhanging vegetation and fine sediment. This research illustrates the importance of using multiple taxa for biological assessments and the need to consider management legacies when investigating responses to management and conservation actions.

  20. 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 estuarine systems and that the EUNIS biotope classification might be used for this purpose. In addition, an original inverse relation between ?-diversity and area was shown; however, its relevance might be questioned.

  1. Benthic macrofauna and ancillary data for San Francisco Bay, California, March to November 1987

    USGS Publications Warehouse

    Schemel, Laurence E.; Ota, A.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)

  2. Multiple tube sampler for benthic and pelagic invertebrates in shallow wetlands

    USGS Publications Warehouse

    Euliss, N.H., Jr.; Swanson, G.A.; MacKay, J.

    1992-01-01

    Sampling devices that minimize bias and function in aquatic habitats used by waterfowl are needed. We devised a multiple tube sampling device for quantitative sampling of small (<3 cm) aquatic invertebrates in wetlands. The sampler reduced bias associated with sampling macroinvertebrates that utilize the benthic-pelagic interface because it simultaneously collects benthic and water column invertebrates. The sampler was statistically superior to other sampling devices because each sampling effort provided 4 subsamples and a within-sample variance that could be estimated. The device also was durable and reasonably inexpensive to construct.

  3. 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 species diversity and abundance of benthic macroinvertebrate fauna, it was found that benthic communities are highly affected by all the environmental parameters governing the distribution and diversity variation of the macrofaunal community in Pondicherry mangroves. Salinity, dissolved oxygen levels, organic matter content, sulphide concentration were the most significant parameters. PMID:23937801

  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. Invertebrate drift and benthic community dynamics in a lowland neotropical stream, Costa Rica

    Microsoft Academic Search

    Alonso Ramírez; Catherine M. Pringle

    1998-01-01

    In this study we quantified invertebrate drift and related it to the structure of the benthic community, over a 6–8 month\\u000a period, in a 4th-order tropical stream in Costa Rica. Relative to reports from similar-sized temperate and tropical streams,\\u000a drift densities were high (2-fold greater: mean 11.2 m?3; range 2.5–25 m?3), and benthic insect densities were relatively low (>3-fold lower:

  6. Layered Liquids

    NSDL National Science Digital Library

    John Eichinger

    2009-05-30

    This activity involves an exploration of density. Why does oil float on water? How does drain cleaner sink down into the clogged pipe right through standing water? These questions will be answered as students make a layered "parfait" of colored liquids ba

  7. Quantitative 'deep-time' palaeoclimate reconstruction using large benthic foraminifera

    NASA Astrophysics Data System (ADS)

    Evans, D.; Müller, W.; Renema, W.

    2012-04-01

    Despite some promising work demonstrating that the geochemistry of large benthic foraminifera (LBF) faithfully records their environment [e.g. 1], the full potential of these organisms for palaeoclimate reconstruction has not been realised. Planktic foraminifera are routinely used to assess the temperature and pH (amongst other parameters) of the past oceans but are short lived and currently offer only limited information regarding seasonal change. In contrast, LBF may live for several years, particularly the large and widespread Paleogene genera such as Nummulites [2]. These foraminifera therefore offer the potential for quantitative reconstruction of seasonal changes of ambient seawater temperature and chemistry. In order to investigate the use of LBF for seasonal palaeoclimate and palaeoceanographic reconstruction we analysed both recent and Eocene Operculina ammonoides (from five different reefs in SE Asia and the Great Barrier Reef) as well as Eocene Nummulites djokdjokartae and N. laevigatus (from Java and England respectively). Our results are obtained using the LA-ICPMS system at RHUL featuring a two-volume LA cell characterised by uniform signal response and rapid washout [3], enabling intratest compositional variability to be assessed on a ?m scale. Our results show that recent O. ammonoides modifies its calcite test chemistry according to its environment. Moreover, our data demonstrate that, as in planktic foraminifera, a systematic relationship exists between Mg/Ca and temperature thus enabling the use of LBF for palaeotemperature reconstructions. Because the Nummulitids have a similar peak abundance range to planktic species usually considered to be surface dwelling (20-40 m), results derived from LBF can be considered to be representative of sea surface temperatures. Because the relationship between seawater Mg/Ca and test Mg/Ca has also been calibrated for a Nummulitid (Heterostegina depressa) [4], our data can also be used to better constrain the Mg/Ca ratio of Eocene seawater. Knowledge of this variable is vital for accurate palaeoclimate reconstruction using the Mg/Ca temperature proxy. In addition to Mg/Ca, we have also investigated the use of these organisms as recorders of other important palaeoenvironmental and ocean-chemistry archives. Preliminary data appear to suggest that the use of B/Ca as a pH proxy appears to be viable in the Nummulitids. Furthermore, it appears that inter-ocean differences in chemistry can be evaluated. Finally, the variability of certain trace element systems in LBF calcite can be related to salinity, potentially offering a new and quantitative palaeosalinity proxy. [1] Wefer & Berger, 1980, Science, 209:803. [2] Purton & Brasier, 1999, Geology, 27(8): 711. [3] Müller et al., 2009, JAAS, 24: 209. [4] Segev & Erez, 2006, Geochem. Geophys. Geosyst., 7(2).

  8. 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 and community structuring is more strongly influenced by sediment particle characteristics than by the chemical properties of the water (pH and salinity). Conclusions Infaunal estuarine communities, which are typically adapted to survive relatively acidic conditions, may be less exposed, less sensitive, and less vulnerable than epibenthic or pelagic communities to further acidification of above-sediment waters. These data question the extent to which all marine infaunal communities, including oceanic communities, are likely to be affected by future global CO2-driven acidification. PMID:25396048

  9. The relation between invertebrate drift and two primary controls, discharge and benthic densities, in a large regulated river

    USGS Publications Warehouse

    Kennedy, Theodore A.; Yackulic, Charles B.; Cross, Wyatt F.; Grams, Paul E.; Yard, Michael D.; Copp, Adam J.

    2014-01-01

    1. Invertebrate drift is a fundamental process in streams and rivers. Studies from laboratory experiments and small streams have identified numerous extrinsic (e.g. discharge, light intensity, water quality) and intrinsic factors (invertebrate life stage, benthic density, behaviour) that govern invertebrate drift concentrations (# m?3), but the factors that govern invertebrate drift in larger rivers remain poorly understood. For example, while large increases or decreases in discharge can lead to large increases in invertebrate drift, the role of smaller, incremental changes in discharge is poorly described. In addition, while we might expect invertebrate drift concentrations to be proportional to benthic densities (# m?2), the benthic–drift relation has not been rigorously evaluated. 2. Here, we develop a framework for modelling invertebrate drift that is derived from sediment transport studies. We use this framework to guide the analysis of high-resolution data sets of benthic density and drift concentration for four important invertebrate taxa from the Colorado River downstream of Glen Canyon Dam (mean daily discharge 325 m3 s?1) that were collected over 18 months and include multiple observations within days. Ramping of regulated flows on this river segment provides an experimental treatment that is repeated daily and allowed us to describe the functional relations between invertebrate drift and two primary controls, discharge and benthic densities. 3. Twofold daily variation in discharge resulted in a >10-fold increase in drift concentrations of benthic invertebrates associated with pools and detritus (i.e. Gammarus lacustris and Potamopyrgus antipodarum). In contrast, drift concentrations of sessile blackfly larvae (Simuliium arcticum), which are associated with high-velocity cobble microhabitats, decreased by over 80% as discharge doubled. Drift concentrations of Chironomidae increased proportional to discharge. 4. Drift of all four taxa was positively related to benthic density. Drift concentrations of Gammarus, Potamopyrgus and Chironomidae were proportional to benthic density. Drift concentrations of Simulium were positively related to benthic density, but the benthic–drift relation was less than proportional (i.e. a doubling of benthic density only led to a 40% increase in drift concentrations). 5. Our study demonstrates that invertebrate drift concentrations in the Colorado River are jointly controlled by discharge and benthic densities, but these controls operate at different timescales. Twofold daily variation in discharge associated with hydropeaking was the primary control on within-day variation in invertebrate drift concentrations. In contrast, benthic density, which varied 10- to 1000-fold among sampling dates, depending on the taxa, was the primary control on invertebrate drift concentrations over longer timescales (weeks to months).

  10. Local processes strongly influence post-bleaching benthic recovery in the Lakshadweep Islands

    Microsoft Academic Search

    Rohan Arthur; Terence J. Done; Helene Marsh; Vicki Harriott

    2006-01-01

    The atoll reefs of the Lakshadweep, in the Indian Ocean suffered a catastrophic mortality of hard coral in the wake of the El Niño event of 1998. This study tracked changes to coral and other benthic elements in three atolls in the Lakshadweep from 2000 to 2003. The recovery of coral was highly site-specific, and appeared to be driven by

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

    Microsoft Academic Search

    Brian T. R. Lewis; Guy C. Cochrane

    1990-01-01

    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

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

    Microsoft Academic Search

    Briant T. R. Lewis; Guy C. Cochrane

    1990-01-01

    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. We have used deep-towed seismic methods, including hydrophones mounted on Alvin, to examine the

  13. 27. MIOCENE BENTHIC FORAMINIFER OXYGEN AND CARBON ISOTOPES, SITE 709, INDIAN OCEAN1

    Microsoft Academic Search

    Fay Woodruff; Samuel M. Savin; Linda Abel

    The benthic isotopic record of Miocene Cibicidoides from Site 709 provides a record of conditions in the Indian Ocean at a depth of about 3200 mbsf. As expected, the record qualitatively resembles those of other Deep Sea Drilling Project and Ocean Drilling Program sites. The data are consistent with the scenario for the evolution of thermohaline circulation in the Miocene

  14. A maritime accident provides evidence for alternate stable states in benthic communities on coral reefs

    Microsoft Academic Search

    B. G. Hatcher

    1984-01-01

    An a posteriori examination of the site of a ship wreck on the outer edge of the Great Barrier Reef revealed an unique, macroalgal-dominated benthic community. The persistence of community structure throughout a year of observation in an environment characterised by intensely grazed microalgae, and in the absence of a measurable wreck-derived influence, provides circumstantial evidence that it represents an

  15. Phylogeography of Ponto-Caspian crustaceans: a benthic-planktonic comparison.

    PubMed

    Cristescu, Melania E A; Hebert, Paul D N; Onciu, Teodora M

    2003-04-01

    The Black, Azov, Caspian and Aral Seas, remnants of the intracontinental Paratethys basin, are home to a spectacular diversity of crustaceans. This study examines the past history of the Ponto-Caspian fauna through comparative phylogeographical studies on both benthic and planktonic taxa, based on an examination of nucleotide diversity in the mitochondrial, cytochrome c oxidase subunit 1 (COI) gene. The COI data reveal a striking example of phylogeographical concordance. All species analysed, three amphipods and three cladocerans, are characterized by two monophyletic clades corresponding to the Black and Caspian regions. However, this phylogeographical partition is, on average, four times deeper for the benthic amphipods than for the planktonic cladocerans. Based on standard molecular clocks, the Black and Caspian lineages of benthic crustaceans diverged at varied intervals from 1 to 8 million years ago. By contrast, planktonic lineages are more recent with their divergence occurring in the last million years. Levels of intraspecific polymorphisms are variable and generally lower in planktonic than benthic taxa. The mechanisms responsible for the high diversity of crustaceans in the Ponto-Caspian region are discussed on the basis of these results. PMID:12753217

  16. Benthic suspension feeders: their paramount role in littoral marine food webs

    Microsoft Academic Search

    Josep-Maria Gili; Rafel Coma

    1998-01-01

    In recent years, particular attention has been paid to coupling and energy transfer between benthos and plankton. Because of their abundance, certain benthic suspension feeders have been shown to have a major impact in marine ecosystems. They capture large quantities of particles and might directly regulate primary production and indirectly regulate secondary production in littoral food chains. Suspension feeders develop

  17. 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...

  18. FIELD VALIDATION OF MULTI-SPECIES LABORATORY TEST SYSTEMS FOR ESTUARINE BENTHIC COMMUNITIES

    EPA Science Inventory

    The major objective of the project was to determine the validity of using multispecies laboratory systems to evaluate the response of estuarine benthic communities to an introduced stress. In a 5-year period, experiments in Apalachicola Bay, Florida, and the York River, Virginia,...

  19. Ecotoxicological effect of grounded MV River Princess on the intertidal benthic organisms off Goa

    Microsoft Academic Search

    B. Ingole; S. Sivadas; R. Goltekar; S. Clemente; M. Nanajkar; R. Sawant; C. D'Silva; A. Sarkar; Z. Ansari

    2006-01-01

    The ecotoxicological effects of oil spill from the grounded vessel MV River Princess on the intertidal benthic organisms of Sinquerim–Candolim beach at Goa were investigated. An intertidal expanse of 1 km on either side of the grounded vessel was selected to evaluate the concentration of total petroleum hydrocarbon (TPH) in the sediment and its effects on the composition, abundance and

  20. BOTTOM TRAWLING IMPACTS ON DIVERSITY AND COMPOSITION OF HABITAT-FORMING BENTHIC

    E-print Network

    BOTTOM TRAWLING IMPACTS ON DIVERSITY AND COMPOSITION OF HABITAT-FORMING BENTHIC COMMUNITIES Management Project No.: 539 Title of Thesis: Bottom trawling impacts on diversity and composition of habitat impacts on vulnerable seafloor habitats are an important component of an ecosystem approach to fisheries

  1. Interactions among benthic insects, algae, and bacteria in a geothermally influenced stream. [Helicopsyche borealis (Hagen)

    Microsoft Academic Search

    Lamberti

    1983-01-01

    This dissertation examines the interactions between benthic macroinvertebrates and microorganisms in stream habitats that were exposed to varying levels of geothermal contamination. Stream microcosms were used in situ to evaluate the separate effects of the thermal and chemical components of geothermal effluents on aquatic biota in Big Sulphur Creek, a third-order stream at the Geysers. The thermal component of those

  2. 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...

  3. RELATIONSHIPS BETWEEN WAVE DISTURBANCE AND ZONATION OF BENTHIC INVERTEBRATE COMMUNITIES ALONG A SUBTIDAL

    E-print Network

    to their depth zonation. Few animals lived in permanent tubes or burrows in the crustacean zone. Wave disturbance between community zonation along a depth-dependent gradient of oscillatory substrate motion (gentlyRELATIONSHIPS BETWEEN WAVE DISTURBANCE AND ZONATION OF BENTHIC INVERTEBRATE COMMUNITIES ALONG

  4. Cd in planktonic and benthic foraminiferal shells determined by thermal ionization mass spectrometry

    SciTech Connect

    Rickaby, R.E.M.; Greaves, M.J.; Elderfield, H.

    2000-04-01

    A highly sensitive method for Cd determination in foraminiferal shells by isotope-dilution TIMS has been developed and applied to (1) a more detailed reconstruction of seawater Cd depth profiles for the North Atlantic in the Holocene and at the Last Glacial Maximum (LGM); (2) the analysis of Cd/Ca in individual benthic foraminifera shells; and (3) determination of Cd/Ca in Holocene and glacial planktonic foraminifera. Although Ca has a high first ionization potential, through chemical separation of Cd from the Ca and optimization of the loading technique, it is possible to analyze routine sized samples (10 benthics) with a reproducibility in Cd/Ca of {+-}0.0025 {micro}mol/mol between replicate picks from a single sample. The blank of the method is 1.1 pg, permitting analysis of individual benthics and of planktonic foraminifera. The seawater Cd reconstruction for the LGM is consistent with previous work, but also suggests that depths >2,500 m were ventilated by a northern source of nutrient depleted deep water on the western side of the Mid Atlantic Ridge. Individual benthic Cd/Ca ratios show interspecimen variability which is averaged in routine analysis of multiple specimens. Planktonic Cd/Ca from N. Atlantic cores shows interspecific differences between Globigerina bulloides and Neogloboquadrina pachyderma and Holocene-LGM contrasts which offers potential for use of planktonic Cd/Ca as a palaeochemical tracer.

  5. BENTHIC COMMUNITY STRUCTURE OF THE GREEN AND COLORADO RIVERS THROUGH CANYONLANDS NATIONAL PARK, UTAH, USA

    Microsoft Academic Search

    G. ALLEN HADEN; JOSEPH P. S HANNON; K EVIN P. W ILSON; DEAN W. BLINN

    We sampled the aquatic benthos at 6 remote sites on the Colorado and Green rivers through Canyonlands National Park, Utah, USA. This study provides the first published description of benthic standing mass, invertebrate community composition, and primary carbon source for this portion of the Colorado River system. High suspended sediment concentrations prohibited growth of primary producers. The primary carbon source

  6. Colorado river benthic ecology in Grand Canyon, Arizona, USA: dam, tributary and geomorphological influences

    Microsoft Academic Search

    Lawrence E. Stevens; Joseph P. Shannon; Dean W. Blinn

    1997-01-01

    The serial discontinuity concept (SDC; Ward and Stanford, in Ecology of River Systems, 1983) predicts that recovery of large regulated rivers over distance downstream from a dam is limited by relative tributary size; however, channel geomorphology may also influence the recovery process. We examined the spatial variation in water quality, benthic composition and ash-free dry standing biomass (AFDM) among the

  7. Zonation and seasonality of benthic primary production and community respiration in tropical mangrove forests

    Microsoft Academic Search

    D. M. Alongi

    1994-01-01

    Benthic oxygen consumption and primary production were measured using the bell jar technique in deltaic and fringing mangrove forests of tropical northeastern Australia. In a deltaic forest, rates of sediment respiration ranged from 197 to 1645 µmol O2 m-2 h-1 (mean=836), but did not vary significantly with season or intertidal zone. Gross primary production varied among intertidal zones and seasons,

  8. 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. PMID:22975382

  9. 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...

  10. Land use and the ecology of benthic macroinvertebrate assemblages of high-altitude rainforest streams

    E-print Network

    Chapman, Lauren J.

    Land use and the ecology of benthic macroinvertebrate assemblages of high-altitude rainforest conversion and degradation. In East Africa, the larger tracts of intact rainforest lie largely in protected and pristine forest created by the protection of the high-altitude rainforest in Bwindi Impenetrable National

  11. 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...

  12. The North Pacific giant octopus (Enter-octopus dofleini) is a benthic cephalo-

    E-print Network

    39 The North Pacific giant octopus (Enter- octopus dofleini) is a benthic cephalo- pod fished several attempts to develop a commercial fish- ery for the North Pacific giant octopus (hereafter referred and Game allows commercial harvest of octopus within state wa- ters only as incidental catch managed under

  13. Benthic macrofaunal assemblages of the San Francisco Estuary and Delta, USA

    E-print Network

    Benthic macrofaunal assemblages of the San Francisco Estuary and Delta, USA Bruce Thompson & J distribution of macrobenthic assemblages in the San Francisco Estu- ary and Sacramento­San Joaquin River Delta) a tidal freshwater assemblage in the Delta. Most sites were classified within the same assemblage

  14. The impact of sunlight on inactivation of indicator microorganisms both in river water and benthic biofilms

    Microsoft Academic Search

    Claudia Schultz-Fademrecht; Marc Wichern; Harald Horn

    2008-01-01

    A detailed knowledge on decay or inactivation kinetics of faecal indicator microorganism in rivers is essential for control of bathing water quality. Both reliable inactivation rate coefficients for such kinetics and the knowledge on pathogen accumulation in benthic biofilms are needed for the assessment of river self purification capability and for being able to make decisions for an optimized water

  15. Dispersal as a regional process affecting the local dynamics of marine and stream benthic invertebrates

    Microsoft Academic Search

    Margaret A. Palmer; J. David Allan; Cheryl Ann Butman

    1996-01-01

    Recent work has shown that benthic invertebrate assemblages may be influenced in an ongoing fashion by dispersal. Water-column movements of meiofauna, juvenile insects and marine postlarvae are common and can act to alter greatly local dynamics such as predator-prey and competitive interactions in marine and stream ecosystems. These findings are important because past research on the role of dispersal in

  16. ESTABLISHING REFERENCE CONDITIONS FOR BENTHIC INVERTEBRATE MONITORING IN THE FRASER RIVER CATCHMENT,

    E-print Network

    ESTABLISHING REFERENCE CONDITIONS FOR BENTHIC INVERTEBRATE MONITORING IN THE FRASER RIVER CATCHMENT; (4) creating a family-level predictive model of invertebrate assemblage structure, and testing retained higher numbers of invertebrates than 400-µm-mesh nets, although the overall number of taxa

  17. Benthic invertebrate community structure is influenced by forest succession after clearcut logging in southeastern Alaska

    E-print Network

    Wagner, Diane

    Benthic invertebrate community structure is influenced by forest succession after clearcut logging of invertebrates than cobble habitats. In addition, woody debris also supported a richer and more diverse invertebrate fauna than either cobble or gravel substrates. Maintaining both a woody debris source and a red

  18. 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...

  19. DOWNSTREAM BENTHIC RESPONSES TO SMALL DAM REMOVAL IN A COLDWATER STREAM

    E-print Network

    Stanley, Emily

    DOWNSTREAM BENTHIC RESPONSES TO SMALL DAM REMOVAL IN A COLDWATER STREAM CAILIN H. ORR,* STEVE J Street, Madison, WI 53706, USA ABSTRACT Increased awareness of the negative effects of dams combined with an aging dam infrastructure has led to an increase in dam removals. However, ecological responses

  20. Significance of ATP, carbon, and caloric content of meiobenthic nematodes in partitioning benthic biomass

    Microsoft Academic Search

    J. P. Sikora; W. B. Sikora; C. W. Erkenbrecher; B. C. Coull

    1977-01-01

    Benthic, free-living marine nematodes from two stations, one subtidal, one intertidal, in the North Inlet Estuary, South Carolina, USA, have been characterized by measurement of adenosine triphosphate (ATP), carbon, caloric content, and ash-free dry weight. Two methods of extracting the organisms from the sediment were used. Resulting carbon to ATP ratios and population density data from ongoing North Inlet meiofauna

  1. Spatio-temporal community structure of peat bog benthic desmids on a microscale

    E-print Network

    Spatio-temporal community structure of peat bog benthic desmids on a microscale Jiri´ Neustupa- scale transects were delimited at 4 temperate lowland peat bog localities to investigate spatial represented by dynamics of the common species. Keywords Desmidiales Á Microscale Á Microphytobenthos Á Peat

  2. Small-scale spatial variation of benthic algal assemblages in a peat bog Katerina Cerna n

    E-print Network

    Small-scale spatial variation of benthic algal assemblages in a peat bog Katerina Cerna´ n test Peat bog a b s t r a c t Spatial patterns on a very small scale (10 cm), and the effect microhabitat types were investigated. Samples were taken in a peat bog along linear transects on a scale of 10

  3. Ecological effects of urban stormwater runoff on benthic macroinvertebrates inhabiting the Green River, Massachusetts

    Microsoft Academic Search

    Joel M. Pratt; Robert A. Coler; Paul J. Godfrey

    1981-01-01

    Although it has been demonstrated that urban stormwater can alter the quality of receiving waters, the corresponding impact on aquatic biota remains essentially undocumented. A year-long intensive study, therefore, was implemented to monitor and describe the ecological effects exerted by urban runoff on benthic macroinvertebrates.

  4. Hyperspectral discrimination of coral reef benthic communities in the western Caribbean

    Microsoft Academic Search

    Evanthia Karpouzli; Tim J. Malthus

    2004-01-01

    Determining a subset of wavelengths that best discriminates reef benthic habitats and their associated communities is essential for the development of remote sensing techniques to monitor them. This study measured spectral reflectance from 17 species of western Caribbean reef biota including coral, algae, seagrasses, and sediments, as well as healthy and diseased coral. It sought to extend the spectral library

  5. Status and Trends of Benthic Populations in a Coastal Drowned River Mouth Lake of Lake Michigan

    E-print Network

    Status and Trends of Benthic Populations in a Coastal Drowned River Mouth Lake of Lake Michigan dominated the community, and the oligochaete trophic condition index indicated that, in 1999, the lake the lowest oligochaete density (2,782 m­2), lowest oligochaete trophic condition index scores (1

  6. Influence of light and temperature on the growth rate of estuarine benthic diatoms in culture

    Microsoft Academic Search

    W. Admiraal

    1976-01-01

    Four species of estuarine benthic diatoms: Amphiprora c. f. paludosa W. Smith, Nitzschia c. f. dissipata (Kützing) Grunow, Navicula arenaria Donkin, and Nitzschia sigma (Kützing) W. Smith were grown in unialgal cultures. The growth rates of the diatoms were determined as the rate of increase of the chlorophyll a content of the cultures. The diatoms were cultured at different combinations

  7. Benthic algae as bioindicators of agricultural pollution in the streams and rivers of southern Quebec (Canada)

    E-print Network

    Vincent, Warwick F.

    community structure as well as total benthic algae community were analysed. Water samples were taken that colonisation of the artificial substrates (unglazed ceramic tiles) resulted in biomass levels (Chlorophyll on natural rock substrates. The canonical correspondence analyses showed that pH, conductivity and suspended

  8. 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

  9. 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).

  10. Foraging modes of stream benthic fishes in relation to their predation effects on local prey density

    Microsoft Academic Search

    Mikio Inoue; Masanobu Miyayoshi; Shin Sone

    2005-01-01

    Habitat use and foraging behavior of two benthic insectivorous gobies, Rhinogobius sp. CO (cobalt type) and Rhinogobius sp. DA (dark type), were examined in relation to their predation effects on local prey density in a small coastal stream in southwestern Shikoku, Japan. Correlations among the foraging range, frequency of foraging attempts and current velocity indicated that individuals using fast-current habitats

  11. BIOTROPICA 35(1): 125130 2003 Benthic Community Structure and Invertebrate Drift in a Pacific

    E-print Network

    Benstead, Jon

    BIOTROPICA 35(1): 125­130 2003 Benthic Community Structure and Invertebrate Drift in a Pacific, and freshwater shrimps dominated the benthos and drift. Diel periodicity in drift was not evident. Nine fishes island systems and continental landmasses (often involving distances of hundreds of kilometers) results

  12. 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...

  13. Movers and shakers: nutrient subsidies and benthic disturbance predict biofilm biomass and stable isotope

    E-print Network

    Reynolds, John D.

    Movers and shakers: nutrient subsidies and benthic disturbance predict biofilm biomass and stable. gorbuscha) and chum (O. keta) salmon on stream biofilm. Biofilm is a mix of algae, fungi and bacteria that provides food and habitat and forms the base of these aquatic food webs. 2. We collected rock biofilm

  14. 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...

  15. Influence of organic compounds and light limitation on the growth rate of estuarine benthic diatoms

    Microsoft Academic Search

    Wim Admiraal; Harry Peletier

    1979-01-01

    Ten species of benthic diatoms from the Eems-Dollard estuary were grown in axenic cultures under various combinations of irradiance and supply of organic substrates. Six species were capable of growth in the dark on yeast extract, casamino acids, or glucose. Four of these species grew best in the presence of glucose, whereas the growth of the other two species was

  16. Benthic chamber and profiling landers in oceanography — A review of design, technical solutions and functioning

    Microsoft Academic Search

    A. Tengberg; F. De Bovee; P. Hall; W. Berelson; D. Chadwick; G. Ciceri; P. Crassous; A. Devol; S. Emerson; J. Gage; R. Glud; F. Graziottini; J. Gundersen; D. Hammond; W. Helder; K. Hinga; O. Holby; R. Jahnke; A. Khripounoff; S. Lieberman; V. Nuppenau; O. Pfannkuche; C. Reimers; G. Rowe; A. Sahami; F. Sayles; M. Schurter; D. Smallman; B. Wehrli; P. De Wilde

    1995-01-01

    We review and evaluate the design and operation of twenty-seven known autonomous benthic chamber and profiling lander instruments. We have made a detailed comparison of the different existing lander designs and discuss the relative strengths and weaknesses of each. Every aspect of a lander deployment, from preparation and launch to recovery and sample treatment is presented and compared. It is

  17. 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.

  18. DEVELOPING AND APPLYING A BENTHIC INDEX OF ESTUARINE CONDITION FOR THE VIRGINIAN BIOGEOGRAPHIC PROVINCE

    EPA Science Inventory

    A benthic index of estuarine condition was constructed for the Virginian Biogeographic Province (from Cape Cod, Massachusetts, to the mouth of Chesapeake Bay, Virginia) with data collected during summers of 1990 through 1993 by the US EPA's Environmental Monitoring and Assessment...

  19. Spatio-temporal changes of benthic macroinvertebrates in a cold Arkansas tailwater

    Microsoft Academic Search

    Ronald L. Johnson; George L. Harp

    2005-01-01

    This paper investigates spatial, seasonal and long-term changes in benthic macroinvertebrates in riffles of a cold tailwater. Cold tailwaters initially disrupt previously existing macroinvertebrate assemblages, but little is known about the long-term biological effects of a stable cold thermal regime. Assemblages at an upstream and downstream site of the Little Red River, Arkansas were investigated almost 30 years apart (1971

  20. Long-term changes in benthic Cladocera populations in Lake Myvatn, Iceland

    Microsoft Academic Search

    Arni Einarsson; Erla Björk Örnólfsdóttir

    2004-01-01

    Benthic Cladocera were monitored at five sites in Lake Myvatn, Iceland, over a decade (1990–1999), as part of a programme documenting the population fluctuations of animals at different trophic levels in the lake. The species composition remained relatively stable over the first seven years, but in 1997 the population of Eurycercus lamellatus was greatly reduced at all sites. The following

  1. Surveying a Subsea Lava Flow Using the Autonomous Benthic Explorer (abe)

    Microsoft Academic Search

    Dana R. Yoerger; Albert M. Bradley; Barrie B. Walden; Hanumant Singh; Ralf Bachmayer

    1998-01-01

    This paper summarizes results from the first science deployment of the Autonomous Benthic Explorer (ABE), conducted on the Juan de Fuca Ridge (46°N, 129°W) at depths between 2200 and 2400 m. Using long baseline acoustic transponders, the ABE descended with precision to a preassigned starting point, then executed dead-reckoned tracklines. It followed the bottom at distances between 7 and 20

  2. A PROBABILISTIC ASSESSMENT OF BENTHIC CONDITION OF CALIFORNIA ESTUARIES: RESULTS FROM THE NATIONAL COASTAL ASSESSMENT 1999

    EPA Science Inventory

    As part of the National Coastal Assessment, the Environmental Monitoring and Assessment Program of EPA is conducting a three year evaluation of benthic habitat condition of California estuaries. In 1999, probabilistic sampling for a variety of biotic and abiotic condition indica...

  3. Benthic Bacterial Production and Protozoan Predation in a Silty Freshwater Environment

    Microsoft Academic Search

    C. Wieltschnig; U. R. Fischer; A. K. T. Kirschner; B. Velimirov

    2003-01-01

    The interrelation of heterotrophic bacteria with bacterivorous protists has been widely studied in pelagic environments, but data on benthic habitats, especially in freshwater systems, are still scarce. We present a seasonal study focusing on bacterivory by heterotrophic nanoflagellates (HNF) and ciliates in the silty sediment of a temperate macrophyte-dominated oxbow lake. From January 2001 to February 2002 we monitored the

  4. Correlating environmental changes during early Albian oceanic anoxic event 1B using benthic foraminiferal paleoecology

    Microsoft Academic Search

    Jochen Erbacher; Christoph Hemleben; Brian T. Huber; Molly Markey

    1999-01-01

    The nature and consequences of mid-Cretaceous oceanic anoxic events (OAEs) are the subject of ongoing debate, and recent studies have shown that different scenarios are needed to explain each of these events. Nevertheless, similarities between the different OAEs can be observed. Here, we have reconstructed paleoenvironmental changes during the early Albian OAE 1b using benthic foraminiferal distributions and lithologies in

  5. Rafting of benthic macrofauna: important factors determining the temporal succession of the assemblage on detached macroalgae

    Microsoft Academic Search

    Martin Thiel

    2003-01-01

    Rafting on biotic and abiotic substrata has been reported for many benthic marine invertebrates. Here, I describe important characteristics of common floating substrata and review published studies examining the succession of the assemblage on detached macroalgae to identify the most important factors determining this succession. Floating substrata differ in survival time (i.e. before they disintegrate) and in food value, with

  6. Population Structure and Phylogenetic Characterization of Marine Benthic Archaea in Deep-Sea Sediments

    Microsoft Academic Search

    COSTANTINO VETRIANI; HOLGER W. JANNASCH; BARBARA J. MACGREGOR; DAVID A. STAHL; ANNA-LOUISE REYSENBACH

    1999-01-01

    During the past few years Archaea have been recognized as a widespread and significant component of marine picoplankton assemblages and, more recently, the presence of novel archaeal phylogenetic lineages has been reported in coastal marine benthic environments. We investigated the relative abundance, vertical distribution, phylogenetic composition, and spatial variability of Archaea in deep-sea sediments collected from several stations in the

  7. Spatial Patterns of Benthic Macroinvertebrates in Intertidal Areas of a Southern European Estuary: The Tagus, Portugal

    Microsoft Academic Search

    Ana Maria Rodrigues; Sónia Meireles; Teresa Pereira; Alice Gama; Victor Quintino

    2006-01-01

    This study characterizes the composition and spatial distribution patterns of the benthic macrofauna in the intertidal mudflats of the Tagus estuary, western Portugal. A total of 68 species, more than 226,000 specimens with a total wet weight biomass of approximately 1170 g were identified in 380 sites. The species Streblospio shrubsolii, Cyathura carinata, Tharyx sp., Hydrobia ulvae and Tubificids were the

  8. Arsenic in benthic bivalves of San Francisco Bay and the Sacramento\\/San Joaquin River Delta

    Microsoft Academic Search

    CAROLYN JOHNS; SAMUEL N. LUOMA

    1990-01-01

    Arsenic concentrations were determined in fine-grained, oxidized, surface sediments and in two benthic bivalves, Corbicula sp. and Macoma balthica, within San Francisco Bay, the Sacramento\\/ San Joaquin River Delta, and selected rivers not influenced by urban or industrial activity. Arsenic concentrations in all samples were characteristic of values reported for uncontaminated estuaries. Small temporal fluctuations and low arsenic concentrations in

  9. 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...

  10. 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.

  11. A finite element model to investigate the predator-prey interaction in the benthic habitat

    Microsoft Academic Search

    A. P. C. Rio; R. C. Almeida

    Many marine organisms release into the ocean planktonic larvae which must reach specific sites in order to recruit to the next stage of their life-cycle. Benthic community structure is affected by pelagic environmental conditions, because these conditions determine the probability that larvae will successfully recruit to the adult habitat (1). In particular for sessile species, the population dynamics are regulated

  12. Benthic Herbivores are not Deterred by Brevetoxins Produced by the Red Tide Dinoflagellate Karenia Brevis

    E-print Network

    Sotka, Erik

    . Keywords Herbivory. Harmful algal bloom . Seagrass . Epiphytic algae . Benthic food web Introduction Gulf of Mexico blooms of the planktonic dinoflagellate Karenia brevis are among the oldest reported harmful algal # Springer Science + Business Media, LLC 2009 Abstract Gulf of Mexico blooms of the dinoflagellate Karenia

  13. Herbicide effects on freshwater benthic diatoms: Induction of nucleus alterations and silica cell wall abnormalities

    Microsoft Academic Search

    T. Debenest; J. Silvestre; M. Coste; F. Delmas; E. Pinelli

    2008-01-01

    Benthic diatoms are well known bio-indicators of river pollution by nutrients (nitrogen and phosphorus). Biological indexes, based on diatom sensitivity for non-toxic pollution, have been developed to assess the water quality. Nevertheless, they are not reliable tools to detect pollution by pesticides. Many authors have suggested that toxic agents, like pesticides, induce abnormalities of the diatom cell wall (frustule). High

  14. BIODIVERSITY OF MOBILE BENTHIC FAUNA IN GEODUCK (PANOPEA GENEROSA) AQUACULTURE BEDS IN SOUTHERN PUGET SOUND, WASHINGTON

    E-print Network

    Thuesen, Erik V.

    BIODIVERSITY OF MOBILE BENTHIC FAUNA IN GEODUCK (PANOPEA GENEROSA) AQUACULTURE BEDS IN SOUTHERN, Shelton, WA 98584 ABSTRACT Aquaculture of the geoduck, Panopea generosa Gould, 1850, has increased aquaculture geoduck beds on local fauna is mostly unknown. This study examined the species composition

  15. COMPARATIVE PERFORMANCE OF SIX DIFFERENT BENTHIC MACROINVERTEBRATE SAMPLING METHODS FOR RIVERINE ECOSYSTEMS

    EPA Science Inventory

    At each of 60 sites, we collected benthic macroinvertebrates using six different protocols (including the EMAP methods for non-wadeable rivers) and physical habitat data using the USEPA-EMAP-SW protocols for non-wadeable rivers. We used PCA with physical habitat data and DCA wit...

  16. The effect of drought on benthic invertebrate communities in a lowland river

    Microsoft Academic Search

    C. A. Extence

    1981-01-01

    Benthic macroinvertebrates were sampled at regular intervals from rural and urban sections of the River Roding, Essex, England, in 1975 and 1976. During the latter year a severe drought led to a marked decline in flows and to desiccation of parts of the river bed. In general, drought conditions resulted in an increase in invertebrate populations and possible reasons for

  17. Life histories of benthic invertebrates in a kauri forst stream in northern New Zealand

    Microsoft Academic Search

    D. R. Towns

    1981-01-01

    Life histories of the following 12 benthic invertebrate species were investigated at four sites in the Waitakere River: Potamopyrgus antipodarum (Gastropoda : Hydrobiidae); Paracalliope fiuviatilis (Amphipoda : Eusiridae), Zephlebia (Neozephlebia) sp. and Deleatidium spp. (Ephemeroptera : Leptophlebiidae), Hydora nitida (Coleoptera : Elmidae), Maoridiamesa harrisi, ?Austrocladius sp. and Paratanytarsus agameta (Diptera : Chironomidae), Austrosimulium australense (Diptera : Simuliidae), Aoteapsyche colonica (Trichoptera

  18. Paleoecology of benthic foraminifera from the Miocene of the San Jacinto Basin, Colombia

    NASA Astrophysics Data System (ADS)

    Poveda, John Sebastian; Fiorini, Flavia; Andres Trejos, Raul; Vallejo, Diego Felipe; Pardo, Andres

    2015-04-01

    Quantitative benthic foraminifera analysis was conducted on 34 samples collected from a borehole core (393.72m deep) drilled by Colombian Hydrocarbon Agency (ANH) on 2009 in the San Jacinto basin (Northern Colombia). The aims of the research were to define a taxonomical data-bank of Miocene benthic foraminifera for this region, to use the benthic foraminifera assemblages to interpret the paleoenvironment and to identify paleoenvironmental changes. The bottom of the section was dated between lowest Burdigalian to middle Langhian (20.393-17.721 Ma) based on calcareous nannofossils bioevents: LO Helicosphaera ampliaperta, HCO Sphenolithus belemnos and LCO Sphenolithus heteromorphus. The benthic foraminifera fauna identified in the studied samples is composed for the majority of calcareous hyaline tests and is dominated by infaunal taxas. Species belonging to the genera Uvigerina and Lenticulina are commonly occurring in the studied section together with other species typical of outer-shelf upper-bathyal environment. Cibicidoides spp., abundant in the lower part of the section, abruptly decreases in abundance in the upper part. Species belonging to the opportunistic genera Bulimina and Bolivina are more abundant in the upper part of the section. Variability in the abundance of opportunistic species can be associated with tectonic disturbance on the Sinu-San Jacinto fold belt (NW of Colombia) as a result of collision of the Caribbean plate against NW of South America. The tectonics could lead a perturbation on deep ocean sedimentation and circulation.

  19. Effects of an invertebrate grazer on the spatial arrangement of a benthic microhabitat

    Microsoft Academic Search

    Orlando Sarnelle; Kim W. Kratz; Scott D. Cooper

    1993-01-01

    We demonstrated the effect of an aquatic herbivore on the spatial arrangement of benthic algal biomass within artificial stream channels. Transects of ceramic tiles were exposed to a gradient of snail (Physella) densities in a 30 d experiment. We observed positive effects of snails on the mean abundance of “overstory” algae (the filamentous chlorophyte Cladophora and associated epiphytes), an important

  20. 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...

  1. Mapping coral reef benthic substrates using hyperspectral space-borne images and spectral libraries

    NASA Astrophysics Data System (ADS)

    Kutser, Tiit; Miller, Ian; Jupp, David L. B.

    2006-11-01

    The suitability of Hyperion, the first civilian hyperspectral sensor in space, for mapping coral reef benthic substrates has been investigated in this study. An image of Cairns Reef, in the northern section of the Australian Great Barrier Reef (GBR), was acquired during Hyperion Calibration and Validation activities. A field experiment was carried out on Cairns Reef to collect information about the optical properties of the water in the area and to map benthic cover by means of video transects. An approach was used to classify the Hyperion image that allows convenient mapping of benthic substrate type and water depth simultaneously. A hyperspectral library of radiance at Hyperion altitude was simulated using a spectral library of GBR benthic substrates, a Hydrolight 4.1 radiative transfer model, and an in-house atmospheric model similar to Modtran-3.7. The image was then classified using the Hyperion at-sensor radiance data and the Spectral Angle Mapper metric using the simulated at-sensor spectral library. The results suggest that using spectral libraries created with forward modelling from the sea bottom to top of the atmosphere are useful tools for interpretation of reefs and can give better results in image classification than classifying the image after removing atmospheric and water column effects. The results also suggest that bottom type and water depth can be separated and mapped simultaneously provided hyperspectral data is available.

  2. Paleontological Society New and Renamed Species of Benthic Foraminifera from the Pleistocene Santa Barbara

    E-print Network

    Patterson, Timothy

    Paleontological Society New and Renamed Species of Benthic Foraminifera from the Pleistocene Santa Barbara Formation of California Author(s): R. Timothy Patterson Source: Journal of Paleontology, Vol. 64, No. 5 (Sep., 1990), pp. 681-691 Published by: Paleontological Society Stable URL: http

  3. A Comparison of Benthic Invertebrate Community Composition in the Mississippi and Illinois Rivers, Pool 26

    Microsoft Academic Search

    Henry H. Seagle Jr; Jeffrey C. Hutton; Kenneth S. Lubinski

    1982-01-01

    Ponar, artificial substrate, and draft samples were collected to define benthic invertebrate community composition in Pool 26 at the confluence of the Mississippi and Illinois rivers. Illinois River Ponar samples produced primarily Chironomidae and Oligochaeta; Mississippi River Ponar samples were dominated by Chironomidae and Ephemeroptera. Mississippi River artifical substrates were dominated by Potamyia flava, Hydropsyche orris, and Chironomidae. Illinois River

  4. 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.

  5. 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 both nutrients and toxicants, an important consideration during restoration since there are trophic transfer implications.

  6. 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.

  7. Benthic Food Webs of the Chukchi and Beaufort Seas: Relative Importance of Ultimate Carbon Sources in a Changing Climate

    NASA Astrophysics Data System (ADS)

    Dunton, K. H.; Schonberg, S. V.; Mctigue, N.; Bucolo, P. A.; Connelly, T. L.; McClelland, J. W.

    2014-12-01

    Changes in sea-ice cover, coastal erosion, and freshwater run-off have the potential to greatly influence carbon assimilation pathways and affect trophic structure in benthic communities across the western Arctic. In the Chukchi Sea, variations in the duration and timing of ice cover affect the delivery of ice algae to a relatively shallow (40-50 m) shelf benthos. Although ice algae are known as an important spring carbon subsidy for marine benthic fauna, ice algal contributions may also help initiate productivity of an active microphytobenthos. Recent studies provide clear evidence that the microphytobenthos are photosynthetically active, and have sufficient light and nutrients for in situ growth. The assimilation of benthic diatoms from both sources may explain the 13C enrichment observed in benthic primary consumers throughout the northern Chukchi. On the eastern Beaufort Sea coast, shallow (2-4 m) estuarine lagoon systems receive massive subsidies of terrestrial carbon that is assimilated by a benthic fauna of significant importance to upper trophic level species, but again, distinct 13C enrichment in benthic primary consumers suggests the existence of an uncharacterized food source. Since ice algae are absent, we believe the 13C enrichment in benthic fauna is caused by the assimilation of benthic microalgae, as reflected in seasonally high benthic chlorophyll in spring under replete light and nutrient conditions. Our observations suggest that changes in ice cover, on both temporal and spatial scales, are likely to have significant effects on the magnitude and timing of organic matter delivery to both shelf and nearshore systems, and that locally produced organic matter may become an increasingly important carbon subsidy that affects trophic assimilation and secondary ecosystem productivity.

  8. Interactions among benthic insects, algae, and bacteria in a geothermally influenced stream. [Helicopsyche borealis (Hagen)

    SciTech Connect

    Lamberti, G.A.

    1983-01-01

    This dissertation examines the interactions between benthic macroinvertebrates and microorganisms in stream habitats that were exposed to varying levels of geothermal contamination. Stream microcosms were used in situ to evaluate the separate effects of the thermal and chemical components of geothermal effluents on aquatic biota in Big Sulphur Creek, a third-order stream at the Geysers. The thermal component of those effluents had greater influence than the chemical component in determining benthic community structure. The effects of grazing by the herbivorous caddisfly Helicopsyche borealis (Hagen) on benthic algae and bacteria were experimentally studied in an undisturbed segment of Big Sulphur Creek. Exclusion of Helicopsyche larvae from introduced substrates resulted in high standing crops of algae and bacteria, but a low algal turnover rate. On substrate that was grazed by natural densities of Helicopsyche larvae, algal and bacterial standing crops were reduced by 83-98%, but the turnover rate of algae was substantially increased. Thus, grazing by Helicopsyche resulted in a low-biomass algal community that, because of a high turnover rate, was able to support a high biomass of consumers. These results emphasize the importance of consumer-producer interactions in stream ecosystems; disturbance of either component during geothermal development may result in substantial changes at other trophic levels as well. Complementary studies to those summarized above include (1) comparison of introduced and natural substrates for sampling benthic organisms, (2) distributional analysis of benthic biota along a geothermal gradient, and (3) evaluation of seasonal dynamics of suspended microorganisms in three streams that have different geothermal characteristics. This dissertation concludes with a review of primary consumption patterns in aquatic insects.

  9. Possible energetic linkage between primary production and deep-sea benthic archaea: insight from biogeochemical lipidomics

    NASA Astrophysics Data System (ADS)

    Takano, Yoshinori; Ohkouchi, Naohiko

    2013-04-01

    Marine archaea have been recognized as a cosmopolitan player for global carbon and nitrogen cycles in the water column and sub-seafloor environments. Recent molecular evidence based on lipids and DNA suggests that uncultured benthic archaea dominate biomass in marine sediment, implying past primary production is a crucial factor for their presently ongoing heterotrophy (e.g., 1-4). Focusing on benthic archaeal heterotrophic processes in deep-sea sediment, we preliminarily traced 13C-signature in archaeal lipids to determine de novo and salvage pathway by in situ 13C-experiment. On the basis of the differential 13C-uptake, we suggest that benthic archaea recycles sedimentary relic membrane lipids to minimize the energy expenditure during 405 days (5). The 16S rRNA and quantitative PCR analysis indicated a community shift in the composition of the benthic archaeal community (e.g., Marine Group I, Marine Benthic Group, Miscellaneous Crenarchaeotic Group). In bacteria and eukarya, it is commonly recognized that free fatty acids are incorporated into cells and converted to acyl-CoA, which are eventually incorporated into membrane lipids as a salvage pathway (cf. 6). Considering the suggestion of salvage pathway in archaeal membrane synthesis (7,8), we discuss archaeal heterotrophic processes in terms of possible biogeochemical lipidomics. Reference [1] Biddle et al., (2006) PNAS, 103, 3846-3851. [2] Lipp et al., (2008) Nature, 454, 991-994. [3] Kallmeyer et al., (2012) PNAS, doi: 10.1073/pnas.1203849109 [4] Hinrichs and Inagaki, (2012) Science, 338, 204-205. [5] Takano et al., (2010) Nature Geosci., 3, 858-861. [6] Silbert et al., (1968) J Bacteriol., 95, 1658-1665. [7] Poulter et al., (1988) JACS, 110, 2620-2624. [8] Ohnuma et al., (1996) J Biochem., 119, 541-547.

  10. 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. PMID:25805214

  11. Benthic Primary Production Budget of a Caribbean Reef Lagoon (Puerto Morelos, Mexico)

    PubMed Central

    Naumann, Malik S.; Jantzen, Carin; Haas, Andreas F.; Iglesias-Prieto, Roberto; Wild, Christian

    2013-01-01

    High photosynthetic benthic primary production (P) represents a key ecosystem service provided by tropical coral reef systems. However, benthic P budgets of specific ecosystem compartments such as macrophyte-dominated reef lagoons are still scarce. To address this, we quantified individual and lagoon-wide net (Pn) and gross (Pg) primary production by all dominant functional groups of benthic primary producers in a typical macrophyte-dominated Caribbean reef lagoon near Puerto Morelos (Mexico) via measurement of O2 fluxes in incubation experiments. The photosynthetically active 3D lagoon surface area was quantified using conversion factors to allow extrapolation to lagoon-wide P budgets. Findings revealed that lagoon 2D benthic cover was primarily composed of sand-associated microphytobenthos (40%), seagrasses (29%) and macroalgae (27%), while seagrasses dominated the lagoon 3D surface area (84%). Individual Pg was highest for macroalgae and scleractinian corals (87 and 86 mmol O2 m?2 specimen area d?1, respectively), however seagrasses contributed highest (59%) to the lagoon-wide Pg. Macroalgae exhibited highest individual Pn rates, but seagrasses generated the largest fraction (51%) of lagoon-wide Pn. Individual R was highest for scleractinian corals and macroalgae, whereas seagrasses again provided the major lagoon-wide share (68%). These findings characterise the investigated lagoon as a net autotrophic coral reef ecosystem compartment revealing similar P compared to other macrophyte-dominated coastal environments such as seagrass meadows and macroalgae beds. Further, high lagoon-wide P (Pg: 488 and Pn: 181 mmol O2 m?2 lagoon area d?1) and overall Pg:R (1.6) indicate substantial benthic excess production within the Puerto Morelos reef lagoon and suggest the export of newly synthesised organic matter to surrounding ecosystems. PMID:24367570

  12. 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 ?(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(?) = -2.63 (±0.076) + 0.0138 (±0.0051) × T(R(2) = 0.82, p < 0.01). The ?(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, ?(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. PMID:21805065

  13. 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.

  14. Deep-sea benthic foraminiferal species diversity in the NE Atlantic and NW Arabian sea: a synthesis

    NASA Astrophysics Data System (ADS)

    Gooday, Andrew J.; Bett, Brian J.; Shires, Rizpah; Lambshead, P. John D.

    1998-01-01

    We present a synthesis of species diversity data (Fishers' alpha index, Shannon-Wiener (log 2), ES(100), Rank 1 Dominance) for "live" (stained) foraminifera from five bathyal (1340 m depth) and abyssal (4450-4950 m depth) sites in the NE Atlantic and a 3400 m-deep site in the Arabian Sea. Three Atlantic sites (Porcupine Seabight, BIOTRANS, Porcupine Abyssal Plain) are subject to seasonal phytodetritus inputs that support low diversity populations (8-17 species). In other respects the foraminifera are highly diverse. The meiofaunal fractions (>45 or >63 ?m; including fragmented and phytodetritus species) of abyssal Atlantic samples yielded >110 and >170 species in the 0-1 cm and 0-10 cm layers, respectively; the Arabian Sea sample (0-1 cm layer only) yielded 232 species. In both cases, values for diversity measures were very high. Diversity was rather lower in bathyal Porcupine Seabight samples (0-1 cm layer), which yielded <100 species. The foraminiferal macrofauna (>500 ?m; Porcupine and Madeira Abyssal Plains) was also speciose (113-133 species), but diversity measures were lower and dominance higher than for the meiofauna. All assemblages contained numerous undescribed species, many belonging to poorly known monothalamous, soft-bodied taxa. Sample diversity was influenced by several factors. Combining phytodetrital and sediment populations reduced diversity and increased dominance slightly; the inclusion of deeper sediment layers and finer sieve fractions had the opposite effect. The inclusion of fragments had more impact on macrofaunal than on meiofaunal diversity, although in both cases the effect was inconsistent (either positive or negative). Porcupine and Madeira Abyssal Plain multicore samples (>63 ?m fraction) contained substantially more foraminiferal species than nematode species; the numbers of foraminiferal species in boxcore samples (>500 ?m fraction) were comparable to, or greater than, literature values for macrofaunal taxa such as polychaetes and isopods. Few of the more abundant species at our Atlantic abyssal plain and Arabian Sea sites are endemic. This is consistent with literature evidence that many common deep-sea foraminiferal species are cosmopolitan and implies that global foraminiferal diversity may be more modest than the high sample diversity might suggest. Calcareous foraminifera, which are well-known taxonomically and have a good fossil record, may provide a model for diversity patterns among the deep-sea benthic biota in general.

  15. Polar Layers

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03083 Polar Layers

    This VIS image illlustrates how distinct polar layers appear with no frost cover. This image was collected during the height of summer at the south pole of Mars.

    Image information: VIS instrument. Latitude 80.7S, Longitude 295.6E. 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.

  16. Polar Layers

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site] Context image for PIA03288 Polar Layers

    Late in the summer season, the numerous polar layers are free of frost and easily visible.

    Image information: VIS instrument. Latitude -84.9N, Longitude 135.9E. 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.

  17. PROCEDURES FOR THE DERIVATION OF EQUILIBRIUM PARTITIONING SEDIMENT BENCHMARKS (ESBS) FOR THE PROTECTION OF BENTHIC ORGANISMS: 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 the ...

  18. A culture-based calibration of benthic foraminiferal paleotemperature proxies: delta O-18 and Mg/Ca results

    E-print Network

    Filipsson, H. L.

    Benthic foraminifera were cultured for five months at four temperatures (4, 7, 14 and 21 °C) to establish the temperature dependence of foraminiferal calcite ?18O and Mg/Ca. Two Bulimina species (B. aculeata and B. marginata) ...

  19. 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...

  20. 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...

  1. Comparison of benthic macroinvertebrate assemblages associated with salt marshes in low and high salinity areas of Galveston Bay 

    E-print Network

    Pool, Suzan Samantha

    1999-01-01

    and the benthos using one year of data were completed. Benthic invertebrates were more abundant at West Bay than at Trinity River Delta. Polychaetes dominated at West Bay whereas oligochaetes dominated at Trinity River Delta. Arthropods and molluscs were...

  2. Adult demography and larval processes in coastal benthic populations : intertidal barnacles in Southern California and Baja California

    E-print Network

    Tapia, Fabián

    2005-01-01

    The geographic distribution and dynamics of coastal benthic populations are shaped by physical - biological interactions affecting larval dispersal and the demography of juvenile and adult individuals. This thesis focused ...

  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 insight into the functioning of a deep-sea benthic community and demonstrated how conventional data can be exploited further when combined with state-of-the-art modelling approaches.

  4. Carbon flows in the benthic food web at the deep-sea observatory HAUSGARTEN (Fram Strait)

    NASA Astrophysics Data System (ADS)

    van Oevelen, Dick; Bergmann, Melanie; Soetaert, Karline; Bauerfeind, Eduard; Hasemann, Christiane; Klages, Michael; Schewe, Ingo; Soltwedel, Thomas; Budaeva, Nataliya E.

    2011-11-01

    The HAUSGARTEN observatory is located in the eastern Fram Strait (Arctic Ocean) and used as long-term monitoring site to follow changes in the Arctic benthic ecosystem. Linear inverse modelling was applied to decipher carbon flows among the compartments of the benthic food web at the central HAUSGARTEN station (2500 m) based on an empirical data set consisting of data on biomass, prokaryote production, total carbon deposition and community respiration. The model resolved 99 carbon flows among 4 abiotic and 10 biotic compartments, ranging from prokaryotes up to megafauna. Total carbon input was 3.78±0.31 mmol C m -2 d -1, which is a comparatively small fraction of total primary production in the area. The community respiration of 3.26±0.20 mmol C m -2 d -1 is dominated by prokaryotes (93%) and has lower contributions from surface-deposit feeding macro- (1.7%) and suspension feeding megafauna (1.9%), whereas contributions from nematode and other macro- and megabenthic compartments were limited to <1%. The high prokaryotic contribution to carbon processing suggests that functioning of the benthic food web at the central HAUSGARTEN station is comparable to abyssal plain sediments that are characterised by strong energy limitation. Faunal diet compositions suggest that labile detritus is important for deposit-feeding nematodes (24% of their diet) and surface-deposit feeding macrofauna (˜44%), but that semi-labile detritus is more important in the diets of deposit-feeding macro- and megafauna. Dependency indices on these food sources were also calculated as these integrate direct (i.e. direct grazing and predator-prey interactions) and indirect (i.e. longer loops in the food web) pathways in the food web. Projected sea-ice retreats for the Arctic Ocean typically anticipate a decrease in the labile detritus flux to the already food-limited benthic food web. The dependency indices indicate that faunal compartments depend similarly on labile and semi-labile detritus, which suggests that the benthic biota may be more sensitive to changes in labile detritus inputs than when assessed from diet composition alone. Species-specific responses to different types of labile detritus inputs, e.g. pelagic algae versus sympagic algae, however, are presently unknown and are needed to assess the vulnerability of individual components of the benthic food web.

  5. 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.

  6. Major methodological constraints to the assessment of environmental status based on the condition of benthic communities

    NASA Astrophysics Data System (ADS)

    Medeiros, João Paulo; Pinto, Vanessa; Sá, Erica; Silva, Gilda; Azeda, Carla; Pereira, Tadeu; Quintella, Bernardo; Raposo de Almeida, Pedro; Lino Costa, José; José Costa, Maria; Chainho, Paula

    2014-05-01

    The Marine Strategy Framework Directive (MSFD) was published in 2008 and requires Member States to take the necessary measures to achieve or maintain good environmental status in aquatic ecosystems by the year of 2020. The MSFD indicates 11 qualitative descriptors for environmental status assessment, including seafloor integrity, using the condition of the benthic community as an assessment indicator. Member States will have to define monitoring programs for each of the MSFD descriptors based on those indicators in order to understand which areas are in a Good Environmental Status and what measures need to be implemented to improve the status of areas that fail to achieve that major objective. Coastal and offshore marine waters are not frequently monitored in Portugal and assessment tools have only been developed very recently with the implementation of the Water Framework Directive (WFD). The lack of historical data and knowledge on the constraints of benthic indicators in coastal areas requires the development of specific studies addressing this issue. The major objective of the current study was to develop and test and experimental design to assess impacts of offshore projects. The experimental design consisted on the seasonal and interannual assessment of benthic invertebrate communities in the area of future implementation of the structures (impact) and two potential control areas 2 km from the impact area. Seasonal benthic samples were collected at nine random locations within the impact and control areas in two consecutive years. Metrics included in the Portuguese benthic assessment tool (P-BAT) were calculated since this multimetric tool was proposed for the assessment of the ecological status in Portuguese coastal areas under the WFD. Results indicated a high taxonomic richness in this coastal area and no significant differences were found between impact and control areas, indicating the feasibility of establishing adequate control areas in marine ecosystems. Nevertheless, significant differences were found between different seasons and different years, showing that the coastal benthic communities important temporal variations. Although those variations did not affect the status assessment based on metrics that considered the ratio between sensitive and tolerant taxa, diversity indices showed different classifications between seasons and years. These results indicate the need for a temporal stratification of the monitoring programs. That might be achieved by setting different thresholds for specific seasons or selecting specific monitoring seasons. It might also require a regular assessment of the environmental conditions that support the identification of outlier years, which monitoring results should be carefully considered.

  7. Becquerel Layers

    NASA Technical Reports Server (NTRS)

    2003-01-01

    MGS MOC Release No. MOC2-350, 4 May 2003

    This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows layered sedimentary rock outcrops in Becquerel Crater of western Arabia Terra. These materials were deposited in the crater some time in the distant past, and later eroded to their present form. They probably consist of fine-grained sediments; they could have been deposited directly from dust and/or volcanic ash settling out of the martian atmosphere, or silt and sand settling to the floor of an ancient lake. The image does not provide enough information to distinguish between the two possibilities. The picture is located near 21.5oN, 8.1oW. Sunlight illuminates the scene from the lower left.

  8. An experimental study on the effects of grazing by parrotfishes and role of refuges in benthic community structure

    Microsoft Academic Search

    R. E. Brock

    1979-01-01

    In an experimental study on the effect of parrotfish (probably Scarus taeniurus) grazing on the structure of benthic reef communities, fishes in densities of 0.6 to 1.5 parrotfish per m2 or 9 to 17 g wet weight of fish per m2 of feeding surface were found to have an optimum effect, resulting in the greatest benthic species richness and biomass

  9. Evaluating the Utility of Benthic Foraminiferal Mg\\/Ca Ratios to Questions of Early Cenozoic Climate Change

    Microsoft Academic Search

    K. Billups; D. P. Schrag

    2002-01-01

    We use benthic foraminiferal Mg\\/Ca ratios from two intermediate water depth sites to reconstruct early Cenozoic paleotemperatures. Together with benthic foraminiferal oxygen isotope values from the same cores paleotemperatures can serve to constrain the oxygen isotopic composition of seawater and early Cenozoic (52-30 Ma) ice-volume history. Our results indicate that foraminiferal Mg\\/Ca ratios are highly sensitive to seawater Mg\\/Ca ratios,

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

    Microsoft Academic Search

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

    2009-01-01

    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 0.1m2, cut to a depth of 10cm, and sieved through a 300-?m mesh. A total of 810 species of benthic invertebrates were identified; the majority of taxa (65.4%) new to

  11. Using a Sediment Quality Triad Approach to Evaluate Benthic Toxicity in the Lower Hackensack River, New Jersey

    Microsoft Academic Search

    Mary T. Sorensen; Jason M. Conder; Phyllis C. Fuchsman; Linda B. Martello; Richard J. Wenning

    2007-01-01

    A Sediment Quality Triad (SQT) study consisting of chemical characterization in sediment, sediment toxicity and bioaccumulation\\u000a testing, and benthic community assessments was performed in the Lower Hackensack River, New Jersey. Chemistry data in sediment\\u000a and porewater were evaluated based on the equilibrium partitioning approach and other published information to investigate\\u000a the potential for chemical effects on benthic organisms and communities.

  12. Life and death beneath macrophyte canopies: effects of understory kelps on growth rates and survival of marine, benthic suspension feeders

    Microsoft Academic Search

    J. E. Eckman; D. O. Duggins

    1991-01-01

    Summary  Experiments conducted on rocky bottoms at 7–11 m depth in the San Juan Archipelago, Washington assessed effects of canopies\\u000a of understory kelps on growth of benthic suspension feeders, determined the mechanisms responsible for effects, and assessed\\u000a the influence of kelp canopies on survivorship of benthic fauna. Kelp canopics influenced growth rates of diverse suspension\\u000a feeders. At several sites the musselMytilus

  13. Species diversity variations in Neogene deep-sea benthic foraminifera at ODP Hole 730A, western Arabian Sea

    NASA Astrophysics Data System (ADS)

    Arumugm, Yuvaraja; Gupta, Anil K.; Panigrahi, Mruganka K.

    2014-10-01

    Deep-sea benthic foraminifera are an important and widely used marine proxy to understand paleoceanographic and paleoclimatic changes on regional and global scales, owing to their sensitivity to oceanic and climatic turnovers. Some species of benthic foraminifera are sensitive to changes in water mass properties whereas others are sensitive to organic fluxes and deep-sea oxygenation. Benthic faunal diversity has been found closely linked to food web, bottom water oxygen levels, and substrate and water mass stability. The present study is aimed at analyzing species diversity trends in benthic foraminifera and their linkages with Indian monsoon variability during the Neogene. Species diversity of benthic foraminifera is examined in terms of number of species (S), information function (H), equitability (E) and Sanders' rarefied values, which were combined with relative abundances of high and low productivity benthic foraminifera at Ocean Drilling Program Hole 730A, Oman margin, western Arabian Sea. The Oman margin offers the best opportunity to understand monsoon-driven changes in benthic diversity since summer monsoon winds have greater impact on the study area. The species diversity was higher during the early Miocene Climatic Optimum (˜17.2-16.4 Ma) followed by a decrease during 16.4-13 Ma coinciding with a major increase in Antarctic ice volume and increased formation of Antarctic Bottom Water. All the diversity parameters show an increase during 13-11.6 Ma, a gradual decrease during 11.6-9 Ma and then an increase with a maximum at 7 Ma. Thereafter the values show little change until 1.2 Ma when all the parameters abruptly decrease. The benthic foraminiferal populations and diversity at Hole 730A were mainly driven by the Indian monsoon, and polar waters might have played a minor or no role since early Neogene period as the Arabian Sea is an enclosed basin.

  14. Effects of crayfish (Paranephrops planifrons: Parastacidae) on in?stream processes and benthic faunas: A density manipulation experiment

    Microsoft Academic Search

    Stephanie M. Parkyn; Charles F. Rabeni; Kevin J. Collier

    1997-01-01

    The effects of New Zealand freshwater crayfish or koura (Paranephrops planifrons: Parastacidae) on organic matter processing, sediment accumulation, and benthic invertebrate communities were investigated using four replicate treatments of 0 (control), 4–5 (medium), and 8–11 (high) similar?sized koura in 0.5 m artificial stream channels colonised by benthic invertebrates from a pasture stream, Waikato, New Zealand. Wineberry (Aristotelia serrata) leaf packs

  15. 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.

  16. Sediment transport in the Mississippi Canyon: the role of currents and storm events on optical variability

    E-print Network

    Burden, Cheryl A

    1999-01-01

    Two modes of sediment transport were found to exist in the Mississippi Canyon: the offshelf transport of material in intermediate nepheloid layers originating at depths of 50-175 m and the resuspension and transport of material within the canyon...

  17. Sediment transport in the Mississippi Canyon: the role of currents and storm events on optical variability 

    E-print Network

    Burden, Cheryl A

    1999-01-01

    Two modes of sediment transport were found to exist in the Mississippi Canyon: the offshelf transport of material in intermediate nepheloid layers originating at depths of 50-175 m and the resuspension and transport of material within the canyon...

  18. The mobilisation of sediment and benthic infauna by scallop dredges.

    PubMed

    O'Neill, F G; Robertson, M; Summerbell, K; Breen, M; Robinson, L A

    2013-09-01

    We present the results of experiments to assess the immediate impact of scallop dredging on the seabed sediment and on the inhabiting infauna. The passage of the scallop dredge is shown to homogenise the seabed, flattening sand ripples. The turbulent wake entrains up to the equivalent of a 1 mm layer of sediment per unit of swept width, although an analysis of the finer particles material implies that the suspended silt material must originate from depths of at least 10 mm. The species most abundant in the sediment plume either swim actively in the water column or are found in, or on, the upper layers of the substrate, whereas those most abundant in core samples taken from the sediment, but not present in the net samples, are almost all tube-building or deep burrowing. The vertical stratification of sediment concentration and of animal numbers in the water column suggests that even if some of these species respond actively to the presence of the dredge, once entrained, they are transported more or less passively in the same way as the larger sediment particles. There was no difference between the core samples taken before or after towing suggesting that animals mobilised by the dredge resettle in the tow path. Our analysis does not provide any information regarding the fate of these animals. PMID:23871519

  19. A Comparison of Trichoptera (Caddisfly) Species Diversity From Several Peninsular Florida Waterbodies Using Benthic and Terrestrial Sampling Methods

    NASA Astrophysics Data System (ADS)

    Rasmussen, A. K.; Denson, D. R.

    2005-05-01

    Typically, environmental agencies tasked with water quality bioassessment solely use benthic sampling methods to collect aquatic insects. Because most aquatic insects live in water only as immatures, benthic samples consist largely of larvae. In Trichoptera, and most insect groups, alpha taxonomy is chiefly based on adult reproductive structures, thus specimens from benthic samples in many cases cannot be assigned species names. Therefore, benthic sampling gives a limited picture of species diversity within aquatic insect communities and may result in monitoring programs not detecting biological impairment involving population losses or declines. In this study of several waterbodies on the Florida peninsula we compare caddisfly species diversity in samples collected using benthic protocols used by the Florida Department of Environmental Protection with that of samples of adult caddisflies collected using UV-blacklight. Light-trap samples yielded significantly higher numbers of both caddisfly individuals and taxa. Benthic samples because of smaller sample sizes and genus-level determinations gave relatively incomplete characterizations of caddisfly community structure. So that aquatic communities can be better understood and protected, we recommend that environmental agencies begin to incorporate additional sampling methods such as light trapping into their assessment and monitoring programs.

  20. Dissolved organic carbon concentration controls benthic primary production: results from in situ chambers in north-temperate lakes

    USGS Publications Warehouse

    Godwin, Sean C.; Jones, Stuart E.; Weidel, Brian C.; Solomon, Christopher T.

    2014-01-01

    We evaluated several potential drivers of primary production by benthic algae (periphyton) in north-temperate lakes. We used continuous dissolved oxygen measurements from in situ benthic chambers to quantify primary production by periphyton at multiple depths across 11 lakes encompassing a broad range of dissolved organic carbon (DOC) and total phosphorous (TP) concentrations. Light-use efficiency (primary production per unit incident light) was inversely related to average light availability (% of surface light) in 7 of the 11 study lakes, indicating that benthic algal assemblages exhibit photoadaptation, likely through physiological or compositional changes. DOC alone explained 86% of the variability in log-transformed whole-lake benthic production rates. TP was not an important driver of benthic production via its effects on nutrient and light availability. This result is contrary to studies in other systems, but may be common in relatively pristine north-temperate lakes. Our simple empirical model may allow for the prediction of whole-lake benthic primary production from easily obtained measurements of DOC concentration.

  1. A baseline study of benthic community associated with Amphioxus Sand in subtropical Hong Kong.

    PubMed

    Chen, Y; Cheung, S G; Shin, P K S

    2013-07-15

    An annual investigation on the seasonal changes of benthic community structure associated with Amphioxus Sand was conducted at two sites in the eastern waters of subtropical Hong Kong, where three species of amphioxus, Branchiostoma belcheri, B. japonicum and B. malayanum coexist. A total of 84 species and 4169 individuals were recorded at Tai Long Wan, whereas a total of 87 species and 3915 individuals were recorded at Pak Lap Wan. Benthic polychaetes were dominant, including high abundance of Onuphis eremita and Prionospio malmgreni. Results of cluster analysis showed significant community structures between the two areas because of difference in sediment granulometry. However, temporal changes within these Amphioxus Sand communities were minimal. In general, the Amphioxus Sand communities in Hong Kong showed higher species richness of Polychaeta as compared with similar studies elsewhere, possibly implying an increased level of organic pollution in Hong Kong waters. PMID:23622836

  2. Significance of microcystin production by benthic communities in water treatment systems of arid zones.

    PubMed

    Hurtado, I; Aboal, M; Zafra, E; Campillo, D

    2008-02-01

    The study of the dynamics of phytobenthic and phytoplankton communities was undertaken, during a year, in the regulation reservoir associated with a water treatment plant (WTP), which provides the city of Murcia (Spain) with drinking water. Water samples were collected in different stages of the treatment. In the reservoir, the presence of dissolved and intracellular microcystins is constant, both in benthos and in plankton. The collected samples show a positive correlation between the dissolved microcystins and the benthic ones in the reservoir itself, as well as in an upstream reservoir (Ojós Reservoir). The treatment process (ozone+clarification+ozone+activated carbon) is very effective in the removal of toxins, and the drinking water produced is totally free of microcystins. The incorporation of the benthic communities in the routine check for the presence of microcystins is recommended, since it is not compulsory according to the current legislation. PMID:17949775

  3. HPLC separation of toxic fraction components extracted from planktonic and benthic Cnidaria.

    PubMed

    Mazzei, M; Garzoglio, R; Mariottini, G L; Carli, A

    1994-01-01

    HPLC separation of crude extract components derived from nematocysts and extranematocystic tissues of macroplanktonic jellyfish Aequorea aequorea and Rhizostoma pulmo and benthic sea-anemones Actinia equina and Anemonia sulcata was carried out by different columns. A satisfactory peak separation was obtained analyzing the toxin of Rhizostoma pulmo by cationic and C18 columns. Low molecular weight fragments were separated by C18 column and U.V. monitored varying pH values and obtaining the displacement of significant peaks. Clear differences between chromatographic plots concerning planktonic and benthic species was evidenced by anionic column; this result can point out a clear ecological analogy between species living in the same environment and a similar toxin biosynthesis, due to selective actions related to both the environment and the phylogenetic relationships; these organisms could have developed similar mechanisms useful to tackle the environment. PMID:7857600

  4. Decalcification of benthic foraminifera due to "Hebei Spirit" oil spill, Korea.

    PubMed

    Lee, Yeon Gyu; Kim, Shin; Jeong, Da Un; Lee, Jung Sick; Woo, Han Jun; Park, Min Woo; Kim, Byeong Hak; Son, Maeng Hyun; Choi, Yang Ho

    2014-10-15

    In order to determine the effects on foraminifera due to spilled crude oil in the "Herbei Spirit" incident, a study of benthic foraminiferal assemblages was carried out on sediment samples collected from the Sogeunri tidal flat, Taean Peninsula, Korea. Breakages of the chambers in the Ammonia beccarii and Elphidium subincertum species of the Sogeunri tidal flat with a low pH (6.98 on average) were marked. These chamber breakages occurred in 71.6% of A. beccarii and are thought to be caused by decalcification due to the fall in pH resulting from the "Hebei Spirit" oil spill. The factors that affect breakage of the chamber in benthic foraminifera under low pH condition may be not only deto decalcification but also to exposure duration of substrata in the tidal flat spilled crude oil. PMID:25113100

  5. Effects of sewage-impacted sediment on reproduction in the benthic crustacean Leptocheirus plumulosus.

    PubMed

    Zulkosky, A M; Ferguson, P L; McElroy, A E

    2002-01-01

    Several organic contaminants in sewage effluent have been shown to elicit an estrogenic response in juvenile fish. Comparatively little emphasis has been placed on assessing these effects in marine invertebrates, particularly benthic organisms inhabiting sediment where lipophilic contaminants tend to persist. The present study examined reproductive effects in the benthic crustacean Leptocheirus plumulosus exposed to sewage-impacted sediment from Jamaica Bay, New York. Data from chronic 28-day tests showed a 50% reduction in the average number of young (juveniles + embryos) produced per surviving female in exposures to sediment from Jamaica Bay (JB). Nonylphenol ethoxylate ('NPEO) concentrations at this site were measured at 44.2 microg/g dw, concentrations two orders of magnitude higher than reference site concentrations in central Long Island Sound (CLIS). Dose-response studies with nonylphenol (NP) amended reference sediment, however, did not significantly affect reproduction suggesting that other contaminants may have contributed to the effects observed. PMID:12408626

  6. Surficial bioturbation and rapid benthic remineralization in the Cape Hatteras shelf/slope region. Final report

    SciTech Connect

    Robert C. Aller; Josephine Y. Aller; C. Lee; J. Kirk Cochran

    1999-03-17

    This is a final report for the DOE of grant DE-FG02-92ER61464 ''Surficial bioturbation and rapid benthic remineralization in the Cape Hatteras shelf slope region''. Over the past 6 years we have participated in a multidisciplinary field study called the Ocean margins Program (OMP) to examine the importance of continental margins in the global carbon cycle. Specifically, we have focused on the southern portion of the Mid-Atlantic Bight between Cape Hatteras and Chesapeake Bay where a large flux of freshwater and organic carbon enters the North Atlantic Ocean. Additionally, during the first stage of this project, we developed the use of CM-a distributions in sediments as a quantitative indicator of benthic C flux and remineralization rates. The primary objective of our research group has been to understand mechanisms and quantify biogeochemical processes in the seabed that affect cycling, flux, and storage of carbon on the ocean margin of the Mid-Atlantic Bight.

  7. Steady-state model describing bioaccumulation of organic contaminants in benthic invertebrates

    SciTech Connect

    Morrison, H.; Lazar, R.; Haffner, G.D. [Univ. of Windsor, Ontario (Canada). Dept. of Biological Sciences; Whittle, D.M. [Department of Fisheries and Oceans, Burlington, Ontario (Canada). Ecotoxicology Division; Gobas, F.A.P.C. [Simon Fraser Univ., Burnaby, British Columbia (Canada)

    1995-12-31

    Although both Canada and the United States use the equilibrium partitioning (EP) method to establish sediment quality criteria guidelines, the ability of this method to accurately predict bioaccumulation has not been thoroughly tested. When predictions of the EP model were compared to PCB data, on five species of benthic invertebrates from western Lake Erie, actual concentrations exceeded predicted concentrations for congeners with log K{sub ow} > 6. A comparison of water/sediment, organism/sediment and organism/water fugacity ratios indicated that western Lake Erie is not in thermodynamic equilibrium. An alternative model to the EP model was derived which does not assume that the system is in equilibrium and provides a mechanism for biomagnification. The model accurately predicted bioaccumulation in benthic invertebrates.

  8. Remote sensing of benthic microalgal biomass with a tower-mounted multispectral scanner

    NASA Technical Reports Server (NTRS)

    Jobson, D. J.; Katzberg, S. J.; Zingmark, R. G.

    1980-01-01

    A remote sensing instrument was mounted on a 50-ft tower overlooking North Inlet Estuary, South Carolina in order to conduct a remote sensing study of benthic microalgae. The instrument was programmed to take multispectral imagery data along a 90 deg horizontal frame in six spectral bands ranging from 400-1050 nm and had a ground resolution of about 3 cm. Imagery measurements were encoded in digital form on magnetic tape and were stored, decoded, and manipulated by computer. Correlation coefficients were calculated on imagery data and chlorophyll a concentrations derived from ground truth data. The most significant correlation occurred in the blue spectral band with numerical values ranging from -0.81 to -0.88 for three separate sampling periods. Mean values of chlorophyll a for a larger section of mudflat were estimated using regression equations. The scanner has provided encouraging results and promises to be a useful tool in sampling the biomass of intertidal benthic microalgae.

  9. Impacts of exploratory drilling for oil and gas on the benthic environment of Georges Bank

    USGS Publications Warehouse

    Neff, J. M.; Bothner, Michael H.; Maciolek, N. J.; Grassle, J. F.

    1989-01-01

    Cluster analysis revealed a strong relationship between community structure and both sediment type and water depth. Little seasonal variation was detected, but some interannual differences were revealed by cluster analysis and correspondence analysis. The replicates from a station always resembled each other more than they resembled any replicates from other stations. In addition, the combined replicates from a station always clustered with samples from that station taken on other cruises. This excellent replication and uniformity of the benthic infaunal community at a station over time made it possible to detect very subtle changes in community parameters that might be related to discharges of drilling fluid and drill cuttings. Nevertheless, no changes were detected in benthic communities of Georges Bank that could be attributed to drilling activities.

  10. Benthic foraminiferal assemblages and trace metals reveal the environment outside the Pearl River Estuary.

    PubMed

    Li, Tao; Xiang, Rong; Li, Tuanjie

    2013-10-15

    We investigated the distribution patterns of the benthic foraminiferal assemblages outside the Pearl River Estuary in relation to trace metals, organic carbon and sedimentary particle fractions. The study area is unpolluted to moderately polluted by Cr, Cu, Pb and Zn and is completely polluted by Ni. The highest levels are found in the western coastal zone. Spatial distributions of the measured elements are strongly related to the behavior of the sedimentary clay fraction. The analyses of species abundance and community diversity as well as subsequent canonical correspondence analysis were used to reveal the relationship between foraminifera data and environmental parameters. Four sampling site groups established by factor analysis were distributed from the coastal area to the inner shelf. Their distribution patterns have a strong correlation with Cu, Pb and Ba. This research shows that benthic foraminifera can be used as bioindicators of trace metal pollutants outside the Pearl River Estuary. PMID:23972678

  11. Benthic community of the Savannah River below a peaking hydropower station

    USGS Publications Warehouse

    Hudson, Patrick L.; Nichols, S. Jerrine

    1986-01-01

    The Savannah River below Hartwell Dam, on the South Carolina-Georgia border, contains at least 206 benthic invertebrate taxa, even though this tailwater undergoes substantial daily fluctuations in water flow, temperature, and dissolved oxygen. Oligochaetes, chironomids, and amphipods dominate the community immediately below the dam. Farther downstream, larger organisms (i.e., Ephemeroptera, Trichoptera, etc.) dominate the benthic community. The high diversity of this system is primarily attributed to the intensive effort we expended to identify invertebrates to species level. We conclude that tailwaters associated with peaking hydropower stations may in fact have the diverse community assemblages found in natural streams and that this has not been recognized by other investigators because the bulk of the fauna is made up of small forms that are easily overlooked. Comparisons of tailwater fauna communities with those in control areas should be limited to rivers of similar size.

  12. PCDD/F release during benthic trawler-induced sediment resuspension.

    PubMed

    Allan, Ian J; Nilsson, Hans C; Tjensvoll, Ingrid; Bradshaw, Clare; Naes, Kristoffer

    2012-12-01

    Benthic trawling can cause the resuspension of large amounts of sediments. Such regular practice in the Grenland fjord system in the south of Norway has the potential to affect the fate, movement, and bioavailability of sediment-associated polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs). A novel mode of exposing passive sampling devices consisting of towing semipermeable membrane devices attached to the trawl net was used to gauge in situ changes in the freely dissolved concentration of PCDD/Fs on benthic trawler-induced sediment resuspension. Significant accumulation of a number of PCDD/F congeners was observed despite the short (5 h) sampler exposure times. On average, a one order of magnitude increase in freely dissolved PCCD/F concentrations was seen within minutes of the sediment being resuspended. This observation was supported by similar changes in filtered PCDD/F concentrations measured by high-volume sampling prior to resuspension and in the sediment plume. PMID:22936523

  13. Fatty acid profiles of benthic environment associated with artificial reefs in subtropical Hong Kong.

    PubMed

    Cheung, Siu Gin; Wai, Ho Yin; Shin, Paul K S

    2010-02-01

    Artificial reefs can enhance habitat heterogeneity, especially in seabed degraded by bottom-dredging and trawling. However, the trophodynamics of such reef systems are not well understood. This study provided baseline data on trophic relationships in the benthic environment associated with artificial reefs in late spring and mid summer of subtropical Hong Kong, using fatty acid profiles as an indicator. Data from sediments collected at the reef base, materials from sediment traps deployed on top and bottom of the reefs, total particulate matter from the water column and oyster tissues from reef surface were subjected to principal component analysis. Results showed variations of fatty acid profiles in the total particulate matter, upper sediment trap and oyster tissue samples collected in the two samplings, indicating seasonal, trophodynamic changes within the reef system. The wastes produced by fish aggregating at the reefs can also contribute a source of biodeposits to the nearby benthic environment. PMID:20034642

  14. The use of benthic mesocosms for the assessment of sediment contamination.

    PubMed

    Fletcher, R; Reynoldson, T B; Taylor, W D

    2001-01-01

    The diagnostic capability of changes in the benthic macroinvertebrate community composition to determine the cause in contaminated sediments were addressed using box core mesocosms subjected to cadmium, atrazine and nutrient enrichment. Intact cores of lake sediment were collected from Lake Erie at four occasions during 1996 and were returned to laboratory where they were maintained and manipulated. The benthic community composition of the artificially polluted mesocosms was compared with field data, collected at the same time as the intact cores, and to untreated control boxes. Community composition was related to the measured environmental variables using multi-dimensional scaling (MDS) and principle axis correlation (PCC). Community responses to different treatments were both different and consistent, suggesting that the community structure of these mesocosms could be used to identify the primary source of impact. PMID:11706790

  15. The Role Of Benthic Foraminifera in Deep-Sea Food Webs and Carbon Cycling

    Microsoft Academic Search

    Andrew J. Gooday; Lisa A. Levin; Peter Linke; Thomas Heeger

    \\u000a Benthic foraminifers are a major element in deep-sea sediment and hard-substrate communities, sometimes accounting for 50%\\u000a or more of eukaryotic biomass. They feed at a low trophic level, consuming mainly planktonic and other detritus and bacteria.\\u000a Some species have metabolic adaptations enabling them to respond quickly to pulsed detrital inputs with rapid rates of reproduction\\u000a and growth. These foraminifers probably

  16. Environmental gradients determining the distribution of benthic macroinvertebrates in Lake Takkobu, Kushiro wetland, northern Japan

    Microsoft Academic Search

    Noriko Takamura; Tomiko Ito; Ryuhei Ueno; Akifumi Ohtaka; Isamu Wakana; Megumi Nakagawa; Youichi Ueno; Hirotsugu Nakajima

    2009-01-01

    Effects of environmental variables on the distribution of benthic macroinvertebrates inhabiting sediments were studied at\\u000a 25 sites along the shoreline of Lake Takkobu in the Kushiro wetland of northern Japan in summer 2003. During the last decade,\\u000a the lake’s status has undergone a drastic shift from clear water dominated by submerged macrophytes to turbid water dominated\\u000a by phytoplankton. The canonical

  17. Dark inorganic carbon fixation sustains the functioning of benthic deep-sea ecosystems

    NASA Astrophysics Data System (ADS)

    Molari, Massimiliano; Manini, Elena; Dell'Anno, Antonio

    2013-01-01

    studies have provided evidence that dark inorganic carbon fixation is an important process for the functioning of the ocean interior. However, its quantitative relevance and ecological significance in benthic deep-sea ecosystems remain unknown. We investigated the rates of inorganic carbon fixation together with prokaryotic abundance, biomass, assemblage composition, and heterotrophic carbon production in surface sediments of different benthic deep-sea systems along the Iberian margin (northeastern Atlantic Ocean) and in the Mediterranean Sea. Inorganic carbon fixation rates in these surface deep-sea sediments did not show clear depth-related patterns, and, on average, they accounted for 19% of the total heterotrophic biomass production. The incorporation rates of inorganic carbon were significantly related to the abundance of total Archaea (as determined by catalyzed reporter deposition fluorescence in situ hybridization) and completely inhibited using an inhibitor of archaeal metabolism, N1-guanyl-1,7-diaminoheptane. This suggests a major role of the archaeal assemblages in inorganic carbon fixation. We also show that benthic archaeal assemblages contribute approximately 25% of the total 3H-leucine incorporation. Inorganic carbon fixation in surface deep-sea sediments appears to be dependent not only upon chemosynthetic processes but also on heterotrophic/mixotrophic metabolism, as suggested by estimates of the chemolithotrophic energy requirements and the enhanced inorganic carbon fixation due to the increase in the availability of organic trophic resources. Overall, our data suggest that archaeal assemblages of surface deep-sea sediments are responsible for the high rates of inorganic carbon incorporation and thereby sustain the functioning of the food webs as well as influence the carbon cycling of benthic deep-sea ecosystems.

  18. Impact of microphytobenthos and macroinfauna on temporal variation of benthic metabolism in shallow coastal sediments

    Microsoft Academic Search

    Min Tang; Erik Kristensen

    2007-01-01

    The impact of microphytobenthos and different abundances of macrofauna (Nereis diversicolor) on temporal variation of benthic metabolism was investigated in laboratory microcosms. Measurements primarily included diurnal fluxes of O2 and CO2 as well as sediment profiles of Chlorophyll a and extracellular polymeric substances (EPS). Net and gross primary production (2–5 and 4–7 mmol CO2 m? 2 h? 1, respectively) were relatively stable

  19. Benthic Oxygen Demand in Three Former Salt Ponds Adjacent to South San Francisco Bay, California

    USGS Publications Warehouse

    Topping, Brent R.; Kuwabara, James S.; Athearn, Nicole D.; Takekawa, John Y.; Parchaso, Francis; Henderson, Kathleen D.; Piotter, Sara

    2009-01-01

    Sampling trips were coordinated in the second half of 2008 to examine the interstitial water in the sediment and the overlying bottom waters of three shallow (average depth 2 meters). The water column at all deployment sites was monitored with dataloggers for ancillary water-quality parameters (including dissolved oxygen, salinity, specific conductance, temperature, and pH) to facilitate the interpretation of benthic-flux results. Calculated diffusive benthic flux of dissolved (0.2-micron filtered) oxygen was consistently negative (that is, drawn from the water column into the sediment) and ranged between -0.5 x 10-6 and -37 x 10-6 micromoles per square centimeter per second (site averages depicted in table 2). Assuming pond areas of 1.0, 1.4, and 2.3 square kilometers for ponds A16, A14, and A3W, respectively, this converts to an oxygen mass flux into the ponds' sediment ranging from -1 to -72 kilograms per day. Diffusive oxygen flux into the benthos (listed as negative) was lowest in pond A14 (-0.5 x 10-6 to -1.8 x 10-6 micromoles per square centimeter per second) compared with diffusive flux estimates for ponds A16 and A3W (site averages -26 x 10-6 to -35 x 10-6 and -34 x 10-6 to -37 x 10-6 micromoles per square centimeter per second, respectively). These initial diffusive-flux estimates are of the order of magnitude of those measured in the South Bay using core-incubation experiments (Topping and others, 2004), which include bioturbation and bioirrigation effects. Estimates of benthic oxygen demand reported herein, based on molecular diffusion, serve as conservative estimates of benthic flux because solute transport across the sediment-water interface can be enhanced by multidisciplinary processes including bioturbation, bioirrigation, ground-water advection, and wind resuspension (Kuwabara and others, 2009).

  20. Modification of benthic communities by territorial damselfish: a multi-species comparison

    NASA Astrophysics Data System (ADS)

    Ceccarelli, D. M.

    2007-12-01

    The effects of territorial damselfish on coral reef benthos have been well-studied for a few relatively large-bodied species with visually distinct territories. Despite a growing body of research demonstrating their abundance, and their effects on algae, corals and other grazers, there has been little research on the effects of the territorial damselfish community as a whole. This study investigated the space occupation, territory composition, and diet of ten damselfish species at three locations: Magnetic and Orpheus Islands (Great Barrier Reef), and Kimbe Bay (Papua New Guinea). Territories were measured, and the composition of benthic communities inside and outside territories was assessed both in situ and from algal collections. The stomach contents of territorial damselfishes were also quantified. Although the larger, previously well-studied species had the most visible effect on the benthic community in their territories, all the smaller species also significantly affected the algal composition, normally with an increase of palatable algae. However, the composition of algal assemblages inside the territories of different species varied considerably. Damselfish territories were highly individual, not just among species, but also among locations. Diets were diverse and indicated a greater degree of omnivory and detritivory than previously thought. At all locations, territories occupied a substantial proportion of the substratum: >25% on Magnetic Island, >50% at Orpheus Island, and ˜50% in Kimbe Bay. Within individual zones, this figure was as high as 70%. The contribution of territorial damselfishes to a range of benthic patterns and processes is considerable, and future benthic studies may need to distinguish more closely between territory and non-territory areas.

  1. Sediment Resuspension Effects on the Benthic Microbial Loop in Experimental Microcosms

    Microsoft Academic Search

    Antonio Pusceddu; Carla Fiordelmondo; Roberto Danovaro

    2005-01-01

    Sediment resuspension induced by anthropogenic disturbance is becoming a major threat of marine coastal ecosystems worldwide.\\u000a The effects of sediment resuspension on the pelagic domain and on macro- and meiobenthos are well documented in the literature,\\u000a whereas the effects on the benthic microbial components are nearly neglected. We have investigated the effects of sediment\\u000a resuspension at two different disturbance levels

  2. Effects of sediment mixing and benthic algal production on fossil pigment stratigraphies

    Microsoft Academic Search

    P. R. Leavitt; S. R. Carpenter

    1989-01-01

    Effects of sediment mixing and benthic algal production on fossil pigment profiles were quantified by fine-interval analysis of cores in a transect across the basin of Paul Lake, MI. Annually resolved profiles (1957–1986) of carotenoids and chlorophyll a from varved sediments at deepwater (15 m) sites were compared to fine-interval (2.5–3.5 mm) stratigraphies from sites with increasing sediment mixing and

  3. Biodegradation of photosynthetically produced extracellular organic carbon from intertidal benthic algae

    Microsoft Academic Search

    Naoshige Goto; Osamu Mitamura; Hisayoshi Terai

    2001-01-01

    14C-labeled extracellular products of a natural microphytobenthic community and two species of benthic diatoms (Nitzschia hybridaeformis and Amphora coffeaeformis) were fractionated into extracellular dissolved organic carbon (14C-EDOC), organic carbon extracted with EDTA (14C-EDTA-extractable OC) and extracellular polymeric substances (14C-EPS). The biodegradation of this labeled extracellular organic carbon by bacteria in sediments was examined to determine the processes of enzymatic degradation

  4. Benthic Macroinvertebrates in the Watershed of an Urban Reservoir in Southeastern Brazil

    Microsoft Academic Search

    P. Moreno; M. Callisto

    2006-01-01

    The Ibirit watershed is subject to several forms of environmental degradation such as the presence of a petroleum refinery\\u000a industry, urbanization of its surrounding landscape, and non treated domestic sewage from over 135,000 inhabitants. Benthic\\u000a macroinvertebrates represent a useful tool in the evaluation of environmental quality through studies of the structure of\\u000a communities and their relationship to anthropic activities within

  5. Decomposition of four macrophytes in wetland sediments: Organic matter and nutrient decay and associated benthic processes

    Microsoft Academic Search

    Daniele Longhi; Marco Bartoli; Pierluigi Viaroli

    2008-01-01

    Decomposition rates of Phragmites australis, Carex riparia, Nuphar luteum and Salvinia natans and benthic processes were measured from December 2003 to December 2004 in a shallow wetland (Paludi di Ostiglia, Northern Italy) by means of litter bags and intact cores incubations. Decay rate was highest for N. luteum (k=0.0152d?1), intermediate for S. natans (k=0.0041d?1) and similar for P. australis (k=0.0027d?1)

  6. Non-lethal effects of ocean acidification on two symbiont-bearing benthic foraminiferal species

    Microsoft Academic Search

    A. McIntyre-Wressnig; J. M. Bernhard; D. C. McCorkle; P. Hallock

    2011-01-01

    We conducted experiments to assess the effect of elevated atmospheric carbon dioxide concentrations on survival, fitness, shell microfabric and growth of two species of symbiont-bearing coral-reef benthic foraminifera, using pCO2 Ievels similar to those likely to occur in shallow marine pore waters in the decades ahead. Foraminifera were cultured at constant temperature and controlled pCO2 (385 ppmv, 1000 ppmv, and

  7. The Impacts of an Invasive Gastropod Batillaria attramentaria on Benthic Habitats in a Central California bay.

    NASA Astrophysics Data System (ADS)

    Dewar, J.; Bowles, C.; Weiskel, H.; Grosholz, E.

    2008-12-01

    Invasive species threaten ecosystem function and native biodiversity in many coastal systems. Studies examining the consequences of invasion often focus only on the responses of local species and fail to consider impacts on the sedimentary as well as the biotic environment. In this study, we examine the impacts of a recently introduced deposit feeding gastropod Batillaria attramentaria on the benthic systems in Bodega Harbor, CA. This species reaches extraordinary densities of >14,000 m-2 over significant areas of high intertidal mudflat suggesting the potential for substantial impacts to sedimentary environments as well as both infaunal and epifaunal communities. We conducted short-term enclosure/exclosure experiments using two densities of Batillaria together with cage controls to measure the effects of Batillaria grazing and bioturbation on standing abundance of microalgae (chl a, sediment grain size and percent organics as well as on common infaunal species. Our results demonstrate that over a short time window, Batillaria has a minimal effect on sediment chl a as well as modest effects on sediment organics and grain size. However, Batillaria had a measurable effect on benthic communities substantially reducing densities of small clams Nutricola tantilla, N. confusa and Gemma gemma in high density enclosure experiments. We also used image analysis of bioturbation of grazing snails in laboratory mesocosms and field mark-recapture studies to quantify the area that would be bioturbated by Batillaria as the invasion continues. This species showed very high growth rates at tidal elevations of +3.0 MHHW and the rate of dispersal suggest that the total impact of these deposit feeders at densities that typically exceed 10,000 m-2 can be substantial. However, we suggest that the potential rate of change to the sediment environment as the result of invasion may occur more slowly than changes to benthic infaunal communities, but that high densities over time are likely to produce broad scale changes to both sedimentary and benthic communities over broad areas of the invaded habitats.

  8. Benthic and pelagic fish biomass of the upper continental slope off eastern Tasmania

    Microsoft Academic Search

    J. L. May; S. J. M. Blaber

    1989-01-01

    Benthic and pelagic fishes were sampled east of Maria Island, Tasmania, at two-monthly intervals from April 1984 to June 1985, from the surface to the bottom (500 m depth), using commercial-sized trawls. Biomass was calculated by the “area swept\\/volume filtered” method and divided by estimated catchability coefficients so that catches from the two sampling gears could be combined. Of the

  9. Microdistribution of benthic invertebrates in a rocky mountain (U.S.A.) stream

    Microsoft Academic Search

    G. Wayne Minshall; Judy N. Minshall

    1977-01-01

    A study of the benthic invertebrate community inhabiting a small, foothill trout stream in the Rocky Mountains of Idaho was conducted over a two-year period. Monthly Hess samples and short-term experiments using substratum-filled trays were used to describe the spatial dispersion of the benthos and to examine the response of invertebrate populations to substratum and current. A method was devised

  10. Boron Isotopes in Benthic Foraminifers: Monospecific Coretop Calibration and Paleo-Reconstruction Through Two Glacial Cycles

    NASA Astrophysics Data System (ADS)

    Hoenisch, B.; Bickert, T.; Hemming, N. G.

    2005-12-01

    One hypothesis for the observed ~30% lower glacial atmospheric pCO2 suggests an increased rain ratio of organic to inorganic carbon during glacial times (Archer and Maier-Reimer, Nature, 1994). In this scenario degradation of the excess organic carbon would cause porewater dissolution of calcite in sediments above the glacial lysocline, thus increasing seawater alkalinity and promoting the uptake of CO2 from the atmosphere into the ocean. This hypothesis was supported by a boron isotope study on mixed benthic foraminifers, which suggested a +0.3 unit higher deep ocean pH during glacial times (Sanyal et al., Nature, 1995). However, the suggested increase in deep ocean carbonate ion concentration ~+100 mumol kg-1 is inconsistent with sedimentary records of carbonate preservation and other geochemical proxy records such as benthic Zn/Ca. Although several studies have shown that the boron isotopic composition of marine biogenic carbonates is primarily controlled by seawater pH, a much higher glacial deep water pH has long been questioned. A likely source of error in the previous deep ocean pH reconstructions may have been the use of mixed benthic foraminifera species. We present the first boron isotope validation study on the single epibenthic foraminifer Cibicidoides wuellerstorfi, which includes coretop and glacial data from a depth profile (1000-4500 m water depth) at the outer Walvis Ridge. In addition we show C. wuellerstorfi data from core ODP 668B in the eastern equatorial Atlantic, the same samples recently used to quantitatively reconstruct surface ocean pH and atmospheric pCO2 through two full glacial cycles (Hoenisch and Hemming, EPSL, 2005). Our monospecific benthic boron isotope data match the shape of the modern pH profile at Walvis Ridge. Importantly, the pH difference between glacial and interglacial deep ocean is much smaller than previously estimated.

  11. The Extent of Benthic Impacts of CCA-Treated Wood Structures in Atlantic Coast Estuaries

    Microsoft Academic Search

    J. S. Weis; P. Weis; T. Proctor

    1998-01-01

    .   To ascertain the extent of impacts from CCA-treated wood bulkheads, we sampled sediments along 10-m transects from these\\u000a bulkheads and from reference sites (either bulkheads made of other materials or unbulkheaded areas nearby) and analyzed the\\u000a fine fraction for metals. We ascertained metal content in resident biota, and analyzed species richness, Shannon-Wiener diversity\\u000a index, and biomass of the benthic

  12. An algal carbon budget for pelagic-benthic coupling in Lake Michigan

    USGS Publications Warehouse

    Fitzgerald, S.A.; Gardner, W.S.

    1993-01-01

    Assimilation and respiration rates of Diporeia sp., an abundant benthic amphipod, and of sediment microheterotrophs were measured in a microcosm study. Release of radioisotope in the form of dissolved organic compounds was much lower than that incorporated and respired for both Diporeia and sediment bacteria. Of the 61 mmol C m-2 of algal C estimated to be deposited during the spring bloom. -from Authors

  13. Distribution, abundance and benthic-pelagic coupling of suspended hydroids on Georges Bank1, 2

    NASA Astrophysics Data System (ADS)

    Concelman, Stephanie; Bollens, Stephen M.; Sullivan, Barbara K.; Madin, Laurence P.; Horgan, Erich; Butler, Mari; van Keuren, Donna

    Clytia spp. hydroids (Phylum Cnidaria), typically attached to a substrate during their asexual, polyp stage, have been found in significant numbers within the mesozooplankton on Georges Bank, North Atlantic Ocean. We examined unpublished historical records of the 1939-1941 cruises of the R/V Atlantis and obtained samples at four-study sites on Georges Bank in June/July 1995 in an attempt to (1) quantify the planktonic and benthic distributions of hydroids on Georges Bank, and (2) determine the coupling between benthic and pelagic habitats of this population. We found that planktonic hydroids have a patchy distribution, varying both spatially and temporally (most abundant in summer months, absent in winter). In 1939-1941 the planktonic hydroids were most broadly distributed following a spring (1940) with strong wind events; hydroids were absent from all samples in 1941. In 1995 we found the highest abundance of planktonic Clytia spp. hydroids (6213.5±1343.6 hydranths m -3) in the central crest of the bank, "downstream" in the Georges Bank circulation pattern from sites along the northeast peak of the Bank where large populations of benthic Clytia spp. hydroids were found (up to 6465 hydranths m -2). Our plankton sampling did not show significant numbers of hydroids in the water column at the Northeast peak sites, indicating that large numbers of planktonic hydroids are not being introduced into the Bank's circulation patterns from off-Bank sites to the northeast (e.g. Scotian shelf). The source population for planktonic hydroids found in the central region of the Bank is most likely the benthic habitats on the northeast peak of the Bank. We hypothesize, and our limited data suggest, that hydroids are detached from the benthos by storm action or other disturbance, advected clockwise with the mean residual circulation, and concentrated and retained in the central, low-advective region of the Bank.

  14. Benthic flux of dissolved nickel into the water column of south San Francisco Bay

    USGS Publications Warehouse

    Topping, B.R.; Kuwabara, J.S.; Parchaso, Francis; Hager, S.W.; Arnsberg, A.J.; Murphy, Fred

    2001-01-01

    Field and laboratory studies were conducted between April, 1998 and May, 1999 to provide the first direct measurements of the benthic flux of dissolved (0.2-micron filtered) nickel between the bottom sediment and water column at three sites in the southern component of San Francisco Bay (South Bay), California. Dissolved nickel and predominant ligands (represented by dissolved organic carbon, and sulfides) were the solutes of primary interest, although a variety of ancillary measurements were also performed to provide a framework for interpretation. Results described herein integrate information needs identified by the State Water Resources Control Board and local stakeholders with fundamental research associated with the U.S. Geological Survey Toxic Substances Hydrology Program. Dissolved-Ni concentrations in the bottom water over the three sampling dates ranged from 34 to 43 nanomoles per liter. Dissolved-macronutrient concentrations in the bottom water were consistently higher (frequently by orders of magnitude) than surface-water determinations reported for similar times and locations (Regional Monitoring Program, 2001). This is consistent with measured positive benthic fluxes for the macronutrients. Benthic-flux estimates for dissolved nickel from core-incubations, when areally averaged over the South Bay, were significant (that is, of equivalent or greater order of magnitude) relative to previously reported freshwater point and non-point sources. This observation is consistent with previous determinations for other metals, and with the potential remobilization of sediment-associated metals that have been ubiquitously distributed in the South Bay. Similar to dissolved-nickel results, benthic flux of macronutrients was also consistently significant relative to surface-water inputs. These results add to a growing body of knowledge that strongly suggests a need to consider contaminant transport across the sediment-water interface when establishing future management strategies for the watershed.

  15. Benthic diatom communities in subalpine pools in New Zealand: relationships to environmental variables

    Microsoft Academic Search

    Cathy Kilroy; Barry J. F. Biggs; Wim Vyverman; Paul A. Broady

    In spite of their potential use as indicators of both present and past environmental conditions, little is known about the\\u000a diatom communities in the many small water bodies at high altitudes in New Zealand. We sampled benthic diatoms at 20 sites\\u000a in a typical subalpine mire pool\\/tarn complex near Arthur’s Pass in South Island, New Zealand in the austral spring

  16. Benthic Diatom Communities in Subalpine Pools in New Zealand: Relationships to Environmental Variables

    Microsoft Academic Search

    Cathy Kilroy; Barry J. F. Biggs; Wim Vyverman; Paul A. Broady

    2006-01-01

    In spite of their potential use as indicators of both present and past environmental conditions, little is known about the\\u000a diatom communities in the many small water bodies at high altitudes in New Zealand. We sampled benthic diatoms at 20 sites\\u000a in a typical subalpine mire pool\\/tarn complex near Arthur’s Pass in South Island, New Zealand in the austral spring

  17. A STUDY OF DIVERSITY AND COMMUNITY COMPARISON INDICES BY BIOASSAY OF COPPER USING COLONIZED BENTHIC MACROINVERTEBRATES

    Microsoft Academic Search

    JIMMY LEE PERKINS

    1981-01-01

    A community bioassay of copper was performed using benthic macroinvertebrates colonized on multiplate substrate samplers. Five copper concentrations ranging from 0.080-2.20 mg\\/l total copper were administered to five artificial streams by a Mount and Brungs proportional dilutor. Free copper ion as Cu('++) ranged from .002-.053 mg\\/l. A sixth stream received no copper and served as a control. Substrates were sampled

  18. Indices, multispecies and synthesis descriptors in benthic assessments: Intertidal organic enrichment from oyster farming

    NASA Astrophysics Data System (ADS)

    Quintino, Victor; Azevedo, Ana; Magalhães, Luísa; Sampaio, Leandro; Freitas, Rosa; Rodrigues, Ana Maria; Elliott, Michael

    2012-09-01

    Intertidal off-bottom oyster culture is shown to cause organic enrichment of the shore and although there are two stressors of interest (the presence of a structure, the trestles, and also the sediment and organic waste from the oysters), these can be separated and their relative impacts determined using an appropriate nested experimental design and data treatments. Although no artificial food sources are involved, the oysters feeding activity and intensity of culture enhances biodeposition and significantly increases the sediment fines content and total organic matter. This in general impoverished the benthic community in culture areas rather than a species succession with the installation of opportunists or a resulting increase in the abundance and biomass of benthic species; the findings can be a direct consequence of the intertidal situation which is less-amenable recruitment of species more common to the subtidal environment. Thus the most appropriate biological descriptors to diagnose the effects associated with the organic enrichment were the multispecies abundance data as well as the primary biological variables species richness and abundance. The effects were however spatially and statistically significantly confined to the area located directly underneath the culture bags compared to the corridors located between the trestles, which do not show such enrichment effects. Synthesis biotic indices were much less effective to diagnose the benthic alterations associated with this organic enrichment. These results show that special attention must be paid when using indices in areas where the organic enrichment induces an impoverishment of the benthic community but not necessarily a species replacement with the installation of opportunists.

  19. Benthic dynamics at the carbonate mound regions of the Porcupine Sea Bight continental margin

    Microsoft Academic Search

    Martin White; Geol Rundsch

    2007-01-01

    A brief review is given of some dynamical processes that influence the benthic dynamics within the carbonate mound provinces\\u000a located at the Porcupine Bank\\/Sea Bight margin, NE Atlantic. The depth range of the mounds in this region (600–1,000 m) marks\\u000a the upper boundary of the Mediterranean outflow water above which Eastern North Atlantic Water dominates. Both water masses\\u000a are carried northwards

  20. Distribution patterns of benthic microalgal standing stock at McMurdo Sound, Antarctica

    Microsoft Academic Search

    Paul K. Dayton; Daniel Watson; Anna Palmisano; James P. Barry; John S. Oliver; Diego Rivera I

    1986-01-01

    During the austral summer of 1975–76 and winter of 1977 benthic and water column chlorophyll a and phaeopigments were measured at several sites along the east and west sides of McMurdo Sound, Antarctica. Estimates of in situ primary productivity were made at some McMurdo Sound locations. Additionally, water column samples were collected at 5 stations in the Ross Sea during

  1. Planktivory in benthic nototheniid fish in McMurdo Sound, Antarctica

    Microsoft Academic Search

    Brian A. Foster; John C. Montgomery

    1993-01-01

    Four species of nototheniid fish were sampled from below the sea ice near Cape Armitage, McMurdo Sound:Pagothenia borchgrevinki from just below the ice 1.5 km offshore,Trematomus bernacchii, Trematomus hansoni andTrematomus centronotus from off the bottom in about 20 m of water near the shore. Scale worms and isopods were conspicuous non-planktonic prey, and present in the three benthic fish species.

  2. Mg\\/Ca and Sr\\/Ca in living benthic foraminiferal tests from the northeastern Atlantic

    Microsoft Academic Search

    K. Tachikawa; C. Fontanier; F. Jorissen; E. Bard

    2003-01-01

    Mg\\/Ca in benthic foraminiferal tests has been recently used as an indicator of bottom water temperature (BWT). We analysed Mg\\/Ca and Sr\\/Ca in living (Rose Bengal stained) and dead foraminifera collected at five stations in the Bay of Biscay in NE Atlantic (43˜44^oN, 2^oW) at interval of 3 to 4 months (1997--2000). Four species with different microhabitat were studied: Cibicidoides

  3. Benthic trophic status and nutrient fluxes in shallow-water sediments

    Microsoft Academic Search

    Anna Engelsen; Stefan Hulth; Leif Pihl; Kristina Sundbäck

    2008-01-01

    Proliferation of fast-growing ephemeral macroalgae in shallow-water embayments constitutes a large-scale environmental change of coastal marine ecosystems. Since inorganic nutrients essential for the initiation and maintenance of macroalgal growth may be supplied from the underlying sediment, we investigated the coupling between benthic inorganic nutrient (mainly N and P) fluxes and sediment properties in 6 bays representing a wide gradient of

  4. Integrating Multibeam Backscatter Angular Response, Mosaic and Bathymetry Data for Benthic Habitat Mapping

    PubMed Central

    Che Hasan, Rozaimi; Ierodiaconou, Daniel; Laurenson, Laurie; Schimel, Alexandre

    2014-01-01

    Multibeam echosounders (MBES) are increasingly becoming the tool of choice for marine habitat mapping applications. In turn, the rapid expansion of habitat mapping studies has resulted in a need for automated classification techniques to efficiently map benthic habitats, assess confidence in model outputs, and evaluate the importance of variables driving the patterns observed. The benthic habitat characterisation process often involves the analysis of MBES bathymetry, backscatter mosaic or angular response with observation data providing ground truth. However, studies that make use of the full range of MBES outputs within a single classification process are limited. We present an approach that integrates backscatter angular response with MBES bathymetry, backscatter mosaic and their derivatives in a classification process using a Random Forests (RF) machine-learning algorithm to predict the distribution of benthic biological habitats. This approach includes a method of deriving statistical features from backscatter angular response curves created from MBES data collated within homogeneous regions of a backscatter mosaic. Using the RF algorithm we assess the relative importance of each variable in order to optimise the classification process and simplify models applied. The results showed that the inclusion of the angular response features in the classification process improved the accuracy of the final habitat maps from 88.5% to 93.6%. The RF algorithm identified bathymetry and the angular response mean as the two most important predictors. However, the highest classification rates were only obtained after incorporating additional features derived from bathymetry and the backscatter mosaic. The angular response features were found to be more important to the classification process compared to the backscatter mosaic features. This analysis indicates that integrating angular response information with bathymetry and the backscatter mosaic, along with their derivatives, constitutes an important improvement for studying the distribution of benthic habitats, which is necessary for effective marine spatial planning and resource management. PMID:24824155

  5. Effect of rapid temperature change on resting routine metabolic rates of two benthic elasmobranchs

    Microsoft Academic Search

    Valentina Di Santo; Wayne A. Bennett

    In this study, flow-through respirometry was used to test the effect of acute temperature change on resting routine metabolic\\u000a rates of two benthic elasmobranchs, Atlantic stingrays, Dasyatis sabina (n = 7) and whitespotted bamboo sharks, Chiloscyllium plagiosum (n = 7) kept under fluctuating temperature regime of 24–27 and 23–25°C, respectively. Atlantic stingrays and whitespotted bamboo\\u000a sharks showed a temperature sensitivity (Q10) of 2.10 (21–31°C)

  6. A physicochemically constrained seawater culturing system for production of benthic foraminifera

    Microsoft Academic Search

    Christopher J. Hintz; G. Thomas Chandler; Joan M. Bernhard; Daniel C. McCorkle; Suzanne M. Havach; Jessica K. Blanks; Timothy J. Shaw

    We present an apparatus and procedure for culturing deep-sea (i.e., bathyal) benthic foraminifera under physicochemically constrained conditions. A 1600-L recirculating culture system was constructed to contribute negligible trace metal contamination; the system was housed in an environmental room maintained near in situ temperatures but at atmospheric pressure. Peristaltic pumps continuously circulated 3 mL seawater min -1 from the reservoir to

  7. Metabolite profiling of the benthic diatom Cocconeis scutellum by GC-MS

    Microsoft Academic Search

    Michela Nappo; Strahil Berkov; Carles Codina; Conxita Avila; Patrizia Messina; Valerio Zupo; Jaume Bastida

    2009-01-01

    Cocconeis scutellum is a benthic diatom producing one or more compounds responsible for the early programmed cell death (apoptosis) of the male\\u000a gonad and the androgenic gland of the protandric shrimp Hippolyte inermis Leach. The metabolite composition of both the ether and butanol extracts was studied by gas chromatography-mass spectrometry\\u000a (GC-MS) in both electron impact (EI) and chemical ionization (CI)

  8. A Comparison of Measures of Riverbed Form for Evaluating Distributions of Benthic Fishes

    Microsoft Academic Search

    Mark L. Wildhaber; Peter J. Lamberson; David L. Galat

    2003-01-01

    A method to quantitatively characterize the bed forms of a large river and a preliminary test of the relationship between bed-form characteristics and catch per unit area of benthic fishes is presented. We used analog paper recordings of bathymetric data from the Missouri River and fish data collected from 1996 to 1998 at both the segment (?10–10-km) and macrohabitat (?10–10-km)

  9. Influence of a microhabitat on the structuring of the benthic macrofaunal community in a mangrove forest

    Microsoft Academic Search

    Koetsu Kon; Hisashi Kurokura; Prasert Tongnunui

    2011-01-01

    Habitat heterogeneity contributes to the maintenance of species diversity; however, little is known about the influence of\\u000a microhabitat heterogeneity on the diversity of mangrove invertebrates. We tested the hypothesis that the structures of benthic\\u000a faunal communities differ among microhabitats because each microhabitat function differs widely according to their physical\\u000a properties. The descriptors of invertebrate assemblages were determined every March (dry

  10. Benthic algal biomass in an unshaded first-order lowland stream: distribution and regulation

    Microsoft Academic Search

    Karina Kjeldsen; Torben M. Iversen; Jens Thorup; Thomas Winding

    1998-01-01

    The vertical distribution of algal biomass in the bed sediment and the seasonal development of benthic algae on stones and\\u000a fine-grained sediments were studied in a small unshaded stream. In addition, field experiments were conducted on the role\\u000a of irradiance and phosphorus in regulating algal biomass.\\u000a \\u000a We found that algal biomass was high at a sediment depth of ten centimetres.

  11. Temporal variability in living deep-sea benthic foraminifera: a review

    Microsoft Academic Search

    Andrew J Gooday; Anthony E Rathburn

    1999-01-01

    The deep ocean environment is disturbed by various processes, many of which involve episodic inputs of organic matter. Some inputs (e.g., phytodetritus at mid-high latitudes in the North Atlantic and Northeast Pacific) are seasonally pulsed, others (e.g., falls of whale carcasses) are irregular and unpredictable, but together, they evoke a variety of responses from the benthic biota. In the case

  12. Benthic primary production in the Ems-Dollard estuary during 1975

    Microsoft Academic Search

    Franciscus Colijn; Loes Venekamp

    1977-01-01

    Summary  Primary production measurements of benthic micro-algal vegetations were carried out with samples from six permanent plots. These permanent plots were assumed to cover the range of salinities and sediments in the estuary. A modification of the standard14C-procedure (COLIJN and VAN BUURT, 1975) was used throught this study. The sensitivity and reliability of the modified method, based on combustion of the

  13. Flows of biomass and structure in an exploited benthic ecosystem in the gulf of California, Mexico

    Microsoft Academic Search

    Francisco Arregu??n-Sánchez; Enrique Arcos; Ernesto A. Chávez

    2002-01-01

    We constructed a mass-balanced model of a benthic ecosystem exploited by shrimp trawlers in the Gulf of California, Mexico. The model is based on the software ecopath with ecosim Version 4a, which takes into account the contribution of functional groups to bycatch. The model represents the state of the ecosystem in 1978–79, and reflects the exploitation rate of shrimp at

  14. A benthic index of environmental condition of Gulf of Mexico estuaries

    Microsoft Academic Search

    Virginia D. Engle; J. Kevin Summers; Gary R. Gaston

    1994-01-01

    An index was developed for estuarine macrobenthos in the Gulf of Mexico that discriminated between areas with degraded environmental\\u000a conditions and areas with undegraded or reference conditions. Test sites were identified as degraded or reference based on\\u000a criteria for dissolved oxygen levels, sediment toxicity tests, and sediment contamination. Discriminant analysis was used\\u000a to identify a suite of measures of benthic

  15. The distribution and ecology of benthic Foraminifera and associated meiofauna in the Northeast Water Polynya, Greenland 

    E-print Network

    Newton, Adrian Charles

    1994-01-01

    by nematodes and Foraminifera, with forams often representing 1/3 to 1/2 of total assemblages (Thiel, 1975, 1983; Gooday, 1986; Alongi and Pichon, 1988). Snider et al. , (1984) identified deep-sea assemblages where Foraminifera constituted 87% of meiofaunal... OF TABLES. . LIST OF FIGURES. INTRODUCTION . . . , . Polynyas and Site Description . Previous Studies of the Arctic Benthos . . . . . Ecology of Benthic Foraminifera . Summary. . . . . . . . . . . . . MATERIALS AND METHODS . 1 . . . . . 3...

  16. Macrophyte development and resuspension regulate the photosynthesis and production of benthic microalgae

    Microsoft Academic Search

    Carsten Lassen; Niels Peter Revsbech; Ole Pedersen

    1997-01-01

    The effect of macrophyte growth on microbenthicphotosynthetic activity was studied in two largeenclosures situated in a shallow, eutrophic lake.Macrophytes were allowed to develop stands of 100%coverage in one enclosure whereas they were harvestedat emergence in the other. Although less than 10% ofthe incident light reached the benthic microphytesbelow the macrophytes at mid-summer, when themacrophytes reached their maximum coverage, theseasonal productivity

  17. Spatial patterns of benthic macroinvertebrates in intertidal areas of a Southern European estuary: the Tagus, Portugal

    Microsoft Academic Search

    Ana Maria Rodrigues; Sónia Meireles; Teresa Pereira; Alice Gama; Victor Quintino

    This study characterizes the composition and spatial distribution patterns of the benthic macrofauna in the intertidal mudflats of the Tagus estuary, western Portugal. A total of 68 species, more than 226,000 specimens with a total wet weight biomass of approximately 1170 g were identified in 380 sites. The speciesStreblospio shrubsolii, Cyathura carinata, Tharyxsp.,Hydrobia ulvaeand Tubificids were the most common and

  18. Waves affect predator–prey interactions between fish and benthic invertebrates

    Microsoft Academic Search

    Friederike Gabel; Stefan Stoll; Philipp Fischer; Martin T. Pusch; Xavier-François Garcia

    2011-01-01

    Little is known about the effects of waves on predator–prey interactions in the littoral zones of freshwaters. We conducted\\u000a a set of mesocosm experiments to study the differential effects of ship- and wind-induced waves on the foraging success of\\u000a littoral fish on benthic invertebrates. Experiments were conducted in a wave tank with amphipods (Gammarus roeseli) as prey, and age-0 bream

  19. Benthic macro-invertebrate community composition within a mangrove/seagrass estuary in northern New Zealand

    NASA Astrophysics Data System (ADS)

    Alfaro, Andrea C.

    2006-01-01

    In the tropics and sub-tropics, estuarine environments with mangrove and seagrass habitats provide important structures and resources for diverse communities of benthic organisms. However, temperate estuarine habitats, especially in mangrove areas, may differ significantly in their community associations and interactions. The community composition of benthic macro-fauna was investigated within temperate Matapouri Estuary, northern New Zealand. The density and distribution of fauna were sampled within six distinctive habitats (mangrove stands, pneumatophore zones, Zostera beds, channels, banks, and sand flats), within four sampling events between December 2002 and September 2003. Each type of habitat was replicated seven times within different locations in the estuary. Counts of all infauna and epifauna within four replicate cores were recorded from each habitat and location. Multidimensional scaling plots were used to identify differences in structure and composition of assemblages among habitats and locations within each sampling event. Results from these benthic samples indicate that Matapouri Estuary has a high overall biodiversity, with distinctive faunal assemblages found within different habitats, and some seasonal variations also apparent. In terms of both number of individuals and taxa per unit area, seagrass beds had the highest numbers and mangrove areas had the lowest numbers, with all other habitats in between. Some locations were found to support a high diversity of organisms across habitats, while other locations had high densities of a few species only. Several physical and biological differences between tropical/sub-tropical and New Zealand's temperate mangrove habitats are put forth as potential reasons for the lower density and diversity of the benthic component observed herein. Further ongoing studies aim to elucidate the structure and interactions within food webs in this estuarine ecosystem.

  20. Geospatial Video Monitoring of Benthic Habitats Using the Shallow-Water Positioning System (SWaPS)

    Microsoft Academic Search

    Diego Lirman; Greg Deangelo

    2007-01-01

    In this project, we describe the application of a geospatial video-based survey technique, the Shallow-Water Positioning System (SWaPS), develop by scientists from NOAA's National Geodetic Survey, to document the abundance, distribution, and damage patterns of benthic organisms in shallow marine habitats that have been historically under-represented in monitoring programs due to the difficulties associated with boat access. SWaPS uses a

  1. A multidisciplinary approach to evaluating impacts of shellfish aquaculture on benthic communities

    Microsoft Academic Search

    J. Grant; A. Hatcher; D. B. Scott; P. Pocklington; C. T. Schafer; G. V. Winters

    1995-01-01

    The impact of suspended mussel culture (Mytilus edulis, M. trossulus) on the benthos of a small Nova Scotia cove (7 m depth) was assessed using meehods involving both benthic metabolism and\\u000a community structure. Due to deposition of mussel feces and pseudofeces, sedimentation rate was higher under the mussel culture\\u000a lines than at an adjacent reference site of similar sediment texture.

  2. Influence of intertidal aquaculture on benthic communities in Pacific Northwest estuaries: Scales of disturbance

    Microsoft Academic Search

    Chariles A. Simenstad; Kurt L. Fresh

    1995-01-01

    We reviewed the scale and intensity of disturbance, and the response of benthic and epibenthic communities, to intertidal\\u000a aquaculture activities in Pacific Northwest estuaries. Available data indicate a spectrum of influences on the ability of\\u000a estuaries to sustain biota unrelated to the cultured species. Certain disturbances, such as adding gravel to mudflats and\\u000a sandflats to enhance clam production, may subtly

  3. Typology of streams in Germany based on benthic invertebrates: Ecoregions, zonation, geology and substrate

    Microsoft Academic Search

    Armin Lorenz; Christian K. Feld; Daniel Hering

    2004-01-01

    Based on 390 benthic invertebrate samples from near-natural streams in Germany we defined eight stream type groups by Non-metric multidimensional scaling (NMS). The taxa lists were restricted to Mollusca, Ephemeroptera, Odonata, Plecoptera, Coleoptera and Trichoptera species and evaluated on presence\\/absence level. At genus level, streams located in the lowlands differ from streams in lower mountainous areas and the Alps, while

  4. 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.

  5. Benthic competition and population dynamics of Monoporeia affinis and Marenzelleria sp. in the northern Baltic Sea

    NASA Astrophysics Data System (ADS)

    Eriksson Wiklund, A.-K.; Andersson, A.

    2014-05-01

    During the last two decades major changes of the benthic fauna have occurred in the northern Baltic Sea, the Gulf of Bothnia. The native amphipod, Monoporeia affinis, has shown a large-scale abundance decrease, while polychaetes, Marenzelleria spp. have invaded the system. Marenzelleria co-exist with the native fauna in the southern Baltic Sea, but in the north the pelagic production might be too low to allow co-existence. Thus, M. affinis might have been out-competed by Marenzelleria in the Gulf of Bothnia. This hypothesis was tested in a competition experiment with a high and a low fresh phytoplankton food supply. When exposed to high food supply both species showed stable or increased biomass over the four week test period. In low food supply, however, M. affinis was found to have a competitive advantage. The experimental data were also related to Baltic Sea monitoring data on primary production, sedimentation and invertebrate abundances. Data from the northern Baltic Sea show that the dominance in the benthic community by M. affinis was replaced by Marenzelleria around 2001. The amphipod decrease might be explained by a marked decrease in primary production during this period. Combining monitoring and experimental data suggests that the invasion of Marenzelleria did not cause the decrease of M. affinis in the northern Baltic Sea; it rather took advantage of the density gap that had occurred. A shift may thus have been established in the Bothnian Sea benthic community.

  6. Effects of mining-derived metals on riffle-dwelling benthic fishes in Southeast Missouri, USA

    USGS Publications Warehouse

    Allert, A.L.; Fairchild, J.F.; Schmitt, C.J.; Besser, J.M.; Brumbaugh, W.G.; Olson, S.J.

    2009-01-01

    We studied the ecological effects of mining-derived metals on riffle-dwelling benthic fishes at 16 sites in the Viburnum Trend lead-zinc mining district of southeast Missouri. Fish community attributes were compared to watershed features and to physical and chemical variables including metal concentrations in sediment pore water and fish. Ozark sculpin (Cottus hypselurus), rainbow darter (Etheostoma caeruleum), Ozark madtom (Noturus albater), and banded sculpin (Cottus carolinae) were the most abundant fishes collected. Species richness and density of riffle-dwelling benthic fishes were negatively correlated with metal concentrations in pore water and in fish. Sculpin densities were also negatively correlated with metal concentrations in pore water and in fish, but positively correlated with distance from mines and upstream watershed area. These findings indicate that metals associated with active lead-zinc mining adversely affect riffle-dwelling benthic fishes downstream of mining areas in the Viburnum Trend. Sculpins may be useful as a sentinel species for assessing mining-related impacts on fish communities.

  7. Patterns of colonization and succession of benthic assemblages in two artificial substrates

    NASA Astrophysics Data System (ADS)

    Spagnolo, A.; Cuicchi, C.; Punzo, E.; Santelli, A.; Scarcella, G.; Fabi, G.

    2014-04-01

    Benthic communities colonizing two different typologies of artificial structures, Tecnoreef® pyramids (PY), and plinth modules (PL), differing for material and shape, were investigated for three years after their deployment on a soft bottom offshore Pedaso (Western Adriatic Sea). The aims were to describe the colonization patterns of benthic assemblages on the two artificial modules, to highlight possible differences between them and to detect the effectiveness of the artificial reef on the ecosystem functioning. The composition of the benthic communities settled on the two types of artificial substrates was different especially just after the reef deployment. Abundance and species richness were higher on PL in the first two years, while an explosion of individuals characterized PY in the third year. This suggested a delay of about one year in the colonization processes on PY likely due to the material and shape. The community settled of the artificial structures was dominated by hard-substrate species which are commonly absent in the natural environment. The occurrence of these organisms enriched the local soft-bottom communities and contributed to habitat diversification. This, together with the importance of these species in the diet of a few reef-dwelling fish, confirms the trophic role and the ecological importance of artificial reefs in areas characterized by soft seabed.

  8. Benthic foraminiferal distributions on the Uruguayan continental margin (South-western Atlantic) and controlling environmental factors

    NASA Astrophysics Data System (ADS)

    de Mello, Camila; Burone, Leticia; Ortega, Leonardo; Franco-Fraguas, Paula; Lahuerta, Nuria; Mahiques, Michel; Marin, Yamandu

    2014-12-01

    The data on benthic foraminifera analysed from 110 box-core samples collected on the Uruguayan continental margin (outer shelf and upper and middle slope, between 36.54-34.64°S and 51.66-53.71°W) were used to evaluate the distribution of the benthic foraminiferal fauna and its relationship with selected abiotic parameters. Primary productivity (PP) and the organic flux (Jz) reaching the sea floor were also estimated for comparison with the foraminiferal distributions. The study area was characterised by elevated PP and Jz values, mainly in the southernmost region, which were associated with thermohaline fronts due to the presence of the Subtropical Shelf Front. The dominant identified taxa were Rhumblerella sepetibaensis (this is the first study recording the ecology of this species) and the opportunistic species Epistominella exigua, Bulimina spp. and Reophax fusiformis, which displayed maximal densities at the southernmost stations, concurrent with the highest Jz levels. The dominant species and vertical foraminiferal distributions responded to the different environmental conditions impacting the area (e.g. PP, grain size, nutrient content), which were most likely related to the hydrodynamic conditions. Hydrodynamic conditions cause differences in PP according to the locations of water masses and their fronts at the surface, according to the depth and current intensity; they determined energetic differences across the benthic environment, controlling organic matter sedimentation as well as grain size, which influenced oxygen availability within sediments.

  9. Biofacies zonation of middle Miocene benthic foraminifera, southeastern San Joaquin basin, California

    SciTech Connect

    Olson, H.C.

    1987-05-01

    The quantitative distribution of benthic foraminifera across the middle Miocene margin of the southeastern San Joaquin basin constitutes a useful tool in applying benthic biofacies zonation to the interpretation of marine paleoenvironments. A middle Miocene transect (near the Luisian/Relizian boundary) was completed across the margin of the southeastern San Joaquin basin near Bakersfild, California. Surface and subsurface fauna encompass strandline through bathyal environments. Quantitative analyses of these fauna result in a useful biofacies zonation for the middle Miocene which can be applied to the interpretation of middle Miocene paleobathymetric and paleogeographic reconstructions, basin analysis, and subsidence histories of the San Joaquin basin. In addition, these data suggest that vertical faunal migration of continental slope fauna has occurred between the middle Miocene and Recent. During the early and middle Miocene, marine temperatures were warmer than today and lower latitudinal gradients prevailed. Stepwise climatic cooling since the middle Miocene has been accompanied by the latitudinal adjustment of surface isotherms, strengthening of the permanent thermocline, and the associated migration of temperature-sensitive planktonic and benthic biofacies. Sedimentologic and seismic evidence in the southeastern San Joaquin basin suggests that present-day lower bathyal biofacies may have been at shallower depths during the middle Miocene. Such migrations would have a significant impact on paleoenvironmental interpretations. Middle Miocene faunal transects from the southeastern San Joaquin basin are compared with equivalent Holocene transects from the eastern Pacific, and differences are discussed in light of this proposal.

  10. Seasonal oxygen-driven migration of mobile benthic fauna affected by natural water column stratification

    NASA Astrophysics Data System (ADS)

    Broszeit, Stefanie; Davenport, John; Bredendieck, Karl; Harman, Luke; McAllen, Rob

    2013-07-01

    Changes in mobile benthic fauna affected by a seasonal oxycline were studied at three-monthly intervals for one year at Lough Hyne, a marine reserve in county Cork, Ireland. This marine lake features regular seasonal anoxic conditions in the deepest part (the Western Trough). Building on previous studies of the effects of the oxycline on demersal fauna, a ROV was used to film the benthic assemblage. Transects above, within and below oxycline depth were filmed on each sampling occasion. Animals were identified and their sizes measured. Data on oxygen concentration of the water column were taken monthly during this period to correlate with the presence and absence of animals in the Trough. Most noteworthy was the establishment of a demersal fish assemblage during normoxic conditions in the deeper areas of the Trough. The goby Lesueurigobius friesii was the most abundant species and their population contained all size classes. They are territorial and build burrows into which they retreated when the ROV approached. The main factor influencing benthic fauna below oxycline depth was oxygen concentration, while the assemblage above the oxycline was never affected by hypoxia. This study shows that mobile animals make use of areas affected by hypoxia as soon as conditions improve, and can establish resident communities.

  11. Benthic community composition on submerged reefs in the central Great Barrier Reef

    NASA Astrophysics Data System (ADS)

    Roberts, T. E.; Moloney, J. M.; Sweatman, H. P. A.; Bridge, T. C. L.

    2015-06-01

    Community dynamics on coral reefs are often examined only in relatively shallow waters, which are most vulnerable to many disturbances. The Great Barrier Reef World Heritage Area (GBRWHA) includes extensive submerged reefs that do not approach sea level and are within depths that support many coral reef taxa that also occur in shallow water. However, the composition of benthic communities on submerged reefs in the GBRWHA is virtually unknown. We examined spatial patterns in benthic community composition on 13 submerged reefs in the central Great Barrier Reef (GBR) at depths of 10-30 m. We show that benthic communities on submerged reefs include similar species groups to those on neighbouring emergent reefs. The spatial distribution of species groups was well explained by depth and cross-shelf gradients that are well-known determinants of community composition on emergent reefs. Many equivalent species groups occurred at greater depths on submerged reefs, likely due to variability in the hydrodynamic environment among reef morphologies. Hard coral cover and species richness were lowest at the shallowest depth (6 m) on emergent reefs and were consistently higher on submerged reefs for any given depth. These results suggest that disturbances are less frequent on submerged reefs, but evidence that a severe tropical cyclone in 2011 caused significant damage to shallow regions of more exposed submerged reefs demonstrates that they are not immune. Our results confirm that submerged reefs in the central GBR support extensive and diverse coral assemblages that deserve greater attention in ecosystem assessments and management decisions.

  12. Benthic macroinvertebrate communities affected by multiple stressors within tidal creeks in northeastern USA harbors

    SciTech Connect

    Papageorgis, C.; Murray, M.; Danis, C.; Yates, L. [IT Corp., Somerset, NJ (United States)

    1995-12-31

    Surveys of water quality, substrate quality and benthic macroinvertebrates were conducted in a variety of tidal creeks located in the vicinity of a municipal solid waste landfill prior to the construction of a leachate collection system. In-Situ water quality data indicated high water temperatures and low dissolved oxygen values along with high turbidites. Sediment chemistry data indicated that all sediment within the study area exceed USEPA heavy metal criteria. Grain size and salinity data indicate that the study area lies within the Mesohaline Mud habitat class. Water quality data remained within similar concentrations with respect to indicators of leachate. The benthic macroinvertebrate community was consistently dominated by opportunistic Polychaete and Oligochaete worms. Both Shannon diversity and Rarefaction curves were used to evaluate trends in species diversity over time. The study includes a comparison to data obtained by USEPA R-EMAP monitoring programs. While large scale biomonitoring programs do not focus on small tidal creeks this study provides useful data regarding baseline benthic communities within tidal creeks affected by multiple stressors to include previous exposure and potential exposure to oil spills, continued point and non-point municipal and industrial wastewater discharges and physical stressors such as elevated water temperatures, homogeneous silt/clay substrate, and depressed dissolved oxygen values.

  13. Response of estuarine benthic communities to zinc contamination: Tests using formulated sediments

    SciTech Connect

    Watzin, M.C. [Univ. of Vermont, Burlington, VT (United States). National Biological Survey; Roscigno, P.F. [Gulf of Mexico OCS Region, New Orleans, LA (United States). Minerals Management Service

    1994-12-31

    Because of historic industrial sources, zinc contamination in Mobile Bay is of widespread concern. Using formulated sediment and a newly developed field technique, the authors examined the effects of a series of concentrations of zinc on the benthic invertebrate community at two sites. A formulated sediment that matches field sediment in grain size distribution and organic matter content was mixed from 11 components and used as the test substrate. Clean sediments and sediments dosed with zinc at concentrations from 250--5,000 mg/kg were exposed in the field on holding racks anchored on the bottom of the bay. The abundance and diversity of benthic invertebrate recruits were used as indicators of sediment quality. The authors found significant differences in both the abundances and species composition of recruits between clean controls and the zinc contaminated sediments. All taxa did not respond similarly to changing zinc concentrations, and effects on some groups were more apparent at lower concentrations. Several families of polychaete worms, harpacticoid copepods, and ostracods appeared to be most sensitive to the zinc. Under certain conditions, some taxa were attracted to zinc contaminated sediments. Taken together, the results suggest that zinc contamination can profoundly affect the nature of the benthic community recruiting into such sediments.

  14. Shoreline urbanization interrupts allochthonous subsidies to a benthic consumer over a gradient of lake size.

    PubMed

    Larson, Eric R; Olden, Julian D; Usio, Nisikawa

    2011-08-23

    The role of resource subsidies across ecosystem boundaries has emerged as an important concept in contemporary ecology. For lake ecosystems, this has led to interest in quantifying the contribution of terrestrial allochthonous carbon to aquatic secondary production. An inverse relationship between habitat area and the role of allochthonous subsidies has been documented on marine islands and assumed for lakes, yet there have been no tests of this pattern among benthic (lake bottom) consumers. Here, we used carbon stable isotopes to trace terrestrial allochthonous and benthic autochthonous carbon use by the crayfish Pacifastacus leniusculus over a gradient of lake area, productivity and urbanization. Consistent with findings from terrestrial islands, habitat size dictated the importance of allochthonous subsidies, as P. leniusculus transitioned from using predominantly terrestrial carbon in small lakes to an increased reliance on autochthonous production in larger lakes. However, shoreline urbanization interacted with this pattern, particularly for small lakes where greater urbanization resulted in reduced use of allochthonous resources. As such, we provide, to our knowledge, the first confirmation of the predicted relationship between habitat size and importance of allochthonous subsidies to lake benthic consumers, but found that urbanization can interfere with this pattern. PMID:21389015

  15. Microbial to reef scale interactions between the reef-building coral Montastraea annularis and benthic algae

    PubMed Central

    Barott, Katie L.; Rodriguez-Mueller, Beltran; Youle, Merry; Marhaver, Kristen L.; Vermeij, Mark J. A.; Smith, Jennifer E.; Rohwer, Forest L.

    2012-01-01

    Competition between reef-building corals and benthic algae is of key importance for reef dynamics. These interactions occur on many spatial scales, ranging from chemical to regional. Using microprobes, 16S rDNA pyrosequencing and underwater surveys, we examined the interactions between the reef-building coral Montastraea annularis and four types of benthic algae. The macroalgae Dictyota bartayresiana and Halimeda opuntia, as well as a mixed consortium of turf algae, caused hypoxia on the adjacent coral tissue. Turf algae were also associated with major shifts in the bacterial communities at the interaction zones, including more pathogens and virulence genes. In contrast to turf algae, interactions with crustose coralline algae (CCA) and M. annularis did not appear to be antagonistic at any scale. These zones were not hypoxic, the microbes were not pathogen-like and the abundance of coral–CCA interactions was positively correlated with per cent coral cover. We propose a model in which fleshy algae (i.e. some species of turf and fleshy macroalgae) alter benthic competition dynamics by stimulating bacterial respiration and promoting invasion of virulent bacteria on corals. This gives fleshy algae a competitive advantage over corals when human activities, such as overfishing and eutrophication, remove controls on algal abundance. Together, these results demonstrate the intricate connections and mechanisms that structure coral reefs. PMID:22090385

  16. Microcystin production in benthic mats of cyanobacteria in the Nile River and irrigation canals, Egypt.

    PubMed

    Mohamed, Zakaria A; el-Sharouny, Hassan M; Ali, Wafaa S M

    2006-04-01

    The present study describes for the first time the species composition and toxicity of benthic cyanobacteria forming mats on the Nile River and irrigation canal sediments in Egypt. A total of 19 species of cyanobacteria were isolated from these mats during this study. The toxicity of the extracts of these species was investigated using Artemia salina assay, mouse bioassay and enzyme linked immunosorbent assay (ELISA). The results showed that all the 19 benthic species isolated from cyanobacterial mats, were toxic to A. salina. Two of these species, namely Calothrix parietina and Phormidium tenue, caused toxicity to mice with neurotoxic signs appeared within 12 h after injection. Whereas, five species showed hepatotoxic effects to mice within 6 h after injection. The results of ELISA showed that all the extracts which had hepatotoxic effects to mice, contained high levels of microcystins with concentrations ranging from 1.6 to 4.1 mg g(-1) dry weight. HPLC analysis for heptotoxic extracts revealed that these extracts contained two peaks corresponding to microcystin-YR and -LR with different proportions. This study suggests that benthic species should be considered along with planktonic species during monitoring of toxic cyanobacteria in water sources, particularly the Nile river which is the main source of drinking water in Egypt. PMID:16564062

  17. Sequential sampling: A cost-effective approach for monitoring benthic macroinvertebrates in environmental impact assessments

    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. As examples, sequential sampling programs have been developed to evaluate the impact of geothermal energy have been developed to evaluate the impact of geothermal energy development on benthic macroinvertebrate diversity at The Geysers, California, and for monitoring the impact of crude oil contamination on chironomid midge (Cricotopus bicinctus (Meigen) and C. mackenziensis Oliver) population densities in the Trail River, Northwest Territories, Canada.

  18. Benthic community recovery from brine impact after the implementation of mitigation measures.

    PubMed

    Del-Pilar-Ruso, Yoana; Martinez-Garcia, Elena; Giménez-Casalduero, Francisca; Loya-Fernández, Angel; Ferrero-Vicente, Luis Miguel; Marco-Méndez, Candela; de-la-Ossa-Carretero, Jose Antonio; Sánchez-Lizaso, José Luis

    2015-03-01

    In many regions, seawater desalination is a growing industry that has its impact on benthic communities. This study analyses the effect on benthic communities of a mitigation measure applied to a brine discharge, using polychaete assemblages as indicator. An eight-year study was conducted at San Pedro del Pinatar (SE Spain) establishing a grid of 12 sites at a depth range of 29-38 m during autumn. Brine discharge started in 2006 and produced a significant decrease in abundance, richness and diversity of polychaete families at the location closest to the discharge, where salinity reached 49. In 2010, a diffuser was deployed at the end of the pipeline in order to increase the mixing, to reduce the impact on benthic communities. After implementation of this mitigation measure, the salinity measured close to discharge was less than 38.5 and a significant recovery in polychaete richness and diversity was detected, to levels similar to those before the discharge. A less evident recovery in abundance was also observed, probably due to different recovery rates of polychaete families. Some families like Paraonidae and Magelonidae were more tolerant to this impact. Others like Syllidae and Capitellidae recovered quickly, although still affected by the discharge, while some families such as Sabellidae and Cirratulidae appeared to recover more slowly. PMID:25543242

  19. Benthic Primary Production in a Saltmarsh Pond: Insights from Fluxes of Dissolved Inorganic Carbon and Oxygen

    NASA Astrophysics Data System (ADS)

    Karolewski, J. S.; Stanley, R. H.; Howard, E. M.; Spivak, A. C.

    2014-12-01

    Salt marshes are important carbon sinks that exist at continental margins and act as mediators in the exchange of nutrients and carbon between terrestrial and marine environments. Within salt marshes, 10-20% of total surface area is covered by marshtop ponds. The fractional area of marshtop ponds is predicted to increase as sea level rises. Despite their potential importance, the balance between autotrophic and heterotrophic processes within such ponds remain poorly understood. To quantify the balance of metabolic fluxes within salt marsh ponds, chemical fluxes of dissolved inorganic carbon (DIC) and dissolved oxygen (DO) were measured in July, 2014 in benthic flux chambers inserted into a salt marsh pond in the Plum Island Estuary Long-Term Ecosystem Research (PIE-LTER) site. Light and dark chambers were used to enable separation of rates of photosynthesis and respiration. Separate chambers were used to enclose sediment covered by primarily benthic microalgae and primarily benthic macroalgae. Net ecosystem metabolism in the microalgae was ~10 and in the macroalgae ~15 mmol C/m2/hour. Respiration rates were ~10 mmol C/m2/ hour for both microalgae and macroalgae. The resulting fluxes of net ecosystem production in the ponds will be compared with overall marsh net ecosystem flux as measured by an eddy flux tower that was located 100 meters from the pond. Additionally, concurrent measurements of DIC and DO allow quantification of the C:O ratio during respiration (i.e. respiratory quotient) in this system.

  20. Overview of hyperspectral remote sensing for mapping marine benthic habitats from airborne and underwater sensors

    NASA Astrophysics Data System (ADS)

    Dierssen, Heidi M.

    2013-09-01

    The seafloor, with its diverse and dynamic benthic habitats varying on meter to centimeter scales, is difficult to accurately monitor with traditional techniques. The technology used to build imaging spectrometers has rapidly advanced in recent years with the advent of smaller sensors and better signal-to-noise capabilities that has facilitated their use in mapping fine-scale benthic features. Here, the use of such sensors for hyperspectral remote sensing of the seafloor from both airborne and underwater platforms is discussed. Benthic constituents provide a so-called optical fingerprint with spectral properties that are often too subtle to be discerned with simple color photographs or multichannel spectrometers. Applications include the recent field validation of the airborne Portable Remote Imaging SpectroMeter (PRISM), a new imaging sensor package optimized for coastal ocean processes in Elkorn Slough California. In these turbid sediment-laden waters, only subtle spectral differences differentiate seafloor with sediment from that with eelgrass. The ultimate goal is to provide robust radiometric approaches that accurately consider light attenuation by the water column and are able to be applied to diverse habitats without considerable foreknowledge.

  1. Contribution of virus-induced lysis and protozoan grazing to benthic bacterial mortality estimated simultaneously in microcosms.

    PubMed

    Fischer, Ulrike R; Wieltschnig, Claudia; Kirschner, Alexander K T; Velimirov, Branko

    2006-08-01

    In contrast to the water column, the fate of bacterial production in freshwater sediments is still a matter of debate. Thus, the importance of virus-induced lysis and protozoan grazing of bacteria was investigated for the first time simultaneously in a silty sediment layer of a mesotrophic oxbow lake. Microcosms were installed in the laboratory in order to study the dynamics of these processes over 15 days. All microbial and physicochemical parameters showed acceptable resemblance to field data observed during a concomitant in situ study, and similar conclusions can be drawn with respect to the quantitative impact of viruses and protozoa on the bacterial compartment. Viral decay rates ranged from undetectable to 0.078 h(-1) (average, 0.033 h(-1)), and the control of bacterial production from below the detection limit to 36% (average, 12%). The contribution of virus-induced lysis of bacteria to the dissolved organic matter pool as well as to benthic bacterial nutrition was low. Ingestion rates of protozoan grazers ranged from undetectable to 24.7 bacteria per heterotrophic nanoflagellate (HNF) per hour (average, 4.8 bacteria HNF(-1) h(-1)) and from undetectable to 73.3 bacteria per ciliate per hour (average, 11.2 bacteria ciliate(-1) h(-1)). Heterotrophic nanoflagellate and ciliates together cropped up to 5% (average, 1%) of bacterial production. The viral impact on bacteria prevailed over protozoan grazing by a factor of 2.5-19.9 (average, 9.5). In sum, these factors together removed up to 36% (average, 12%) of bacterial production. The high number of correlations between viral and protozoan parameters is discussed in view of a possible relationship between virus removal and the presence of protozoan grazers. PMID:16872403

  2. Effects of mussel filtering activity on boundary layer structure

    NASA Astrophysics Data System (ADS)

    van Duren, Luca A.; Herman, Peter M. J.; Sandee, Adri J. J.; Heip, Carlo H. R.

    2006-01-01

    The structure of the benthic boundary layer over a bed of mussels ( Mytilus edulis) was investigated in a large racetrack flume. Flow was observed to be modified both by the physical roughness of the mussel bed and by the momentum input of the exhalent jets of the mussels. Particularly when the mussels were closed, and filtering activity was reduced to a minimum, we observed an internal boundary layer, around 4 cm thick, within the log layer. This internal boundary layer was often masked when the mussels were filtering actively. The presence of an internal boundary layer indicates that the boundary layer is not only structured by friction drag, but that form drag due to roughness elements also plays an important role. Consequently, estimates of bed shear stress based on velocity or Reynolds stress measurements carried out more than a few cm above the bed may be inaccurate. Over inactive mussels the shear velocity in the internal boundary layer (the roughness sub-layer) is smaller and bed shear stress is consequently reduced. Filtration activity of the mussels increased the velocity gradient in the lower layer at low and intermediate velocities, but at higher flow rates velocity profiles were not affected. Clear effects of the exhalent jets on absolute levels of TKE could be measured at all ambient velocities, while the effect on the Reynolds stress was limited. Velocity normalised TKE and Reynolds stress also indicated that the effect of the siphonal currents was limited at high velocities. Our results indicate that mussel filtration activity may have an important effect on exchange processes at the sediment-water interface, but that the extent of the effect is highly dependent on the ambient flow conditions.

  3. Impacts of abrupt CO2 exposure on deep-sea benthic ecosystem functioning

    NASA Astrophysics Data System (ADS)

    Sweetman, A. K.; Bøe, C.; Reigstad, L. J.; Durand, D.

    2013-12-01

    CO2 capture and storage (CCS) is, at present, one of the most promising measures for immediate regulation of CO2 emissions, while non-petroleum energy sources are being sought. Norway has taken a leading role in developing and implementing CCS, whilst international conventions, such as London and OSPAR, and regulations (EU directives) are defining the regulatory framework for CCS, in particular, for CO2 storage in geological structures including those under the seabed. To implement sub-seabed CCS on a global scale it is first necessary to understand how leakage from a CCS reservoir will impact marine ecosystems. To quantify how deep-sea benthic ecosystems respond to elevated levels of CO2, we conducted 4 in-situ benthic chamber lander deployments in a Norwegian fjord at 350m depth in September 2011. During each lander deployment, sediments in one benthic respirometry chamber were exposed to elevated levels of CO2 acidified seawater (up to 20,000 ?atm), while those in a control chamber were exposed to seawater bubbled with air. Each experiment lasted approximately 40 hours. In the CO2 exposed chambers, benthic oxygen demand (respiration) increased and was negatively linearly correlated to pH. While bacterial and archael abundance showed no significant difference between the CO2 exposed chambers and the controls, bacterial and archael abundance was exponentially correlated to benthic oxygen demand, implying that microbial communities played a large role in forcing the strong correlation between respiration and pH. In terms of the effects of CO2 on sediment infauna, more macrofauna burrowed to deeper sediment depths in the CO2 exposed chambers relative to the control to potentially flee the low pH conditions in the experimental treatment. No large differences were seen in Pielou's evenness (J') (a measure of stress in diversity metrics) or the expected number of species between the control and experimental treatments, suggesting that no short-term (< 40 hrs) impacts on infaunal diversity are likely to be seen during a CO2 leakage event. Overall, the results collectively show that sedimentary ecosystems may respond very rapidly to CO2 exposure from a leakage event, and these responses may be manifested by higher respiration, but not necessarily by changes in sediment microbial abundance and faunal diversity. Results on faunal carbon uptakes rates between the 2 treatments will also be presented.

  4. The View from Below: Benthic Foraminifera as Indicators of Deep Water Change in Cariaco Basin

    NASA Astrophysics Data System (ADS)

    Gibson, K. A.; Peterson, L. C.

    2007-12-01

    The Cariaco Basin off northern Venezuela is the largest anoxic basin in the world today after the Black Sea. High productivity from seasonal upwelling and circulation that is restricted by the relatively shallow (145 m) modern sill depth combine to produce the present state of anoxia below a depth of about 300 m, which in turn contributes to the preservation of finely laminated sediments on the basin floor. During the Last Glacial Maximum (LGM), and intermittently throughout the late Quaternary, anoxic conditions were interrupted and sediments show clear evidence of bioturbation and chemical signatures for the presence of oxygen. This implies a switch in the balance between oxygen supply and demand, the oceanographic and climatic controls for which are not fully understood. Benthic foraminifera preserved during intervals of deep basin oxygenation provide insights into the deep water conditions at those times. We report here benthic census data from the LGM section in ODP Site 1002. At first glance, oxygen in the deep waters during a time of lowered glacial sea level would seem counterintuitive since Cariaco Basin would have been largely isolated from the open Caribbean Sea and even more restricted in its circulation by inlet sills that shoaled to no more than 30 m depth. The paradigm that has emerged to date argues for reduced surface productivity and decreased oxygen consumption from organic remineralization as the key to the oxic conditions. However, benthic foraminifera suggest that increased salinity may play a role in driving basin ventilation at this time. Benthic foraminiferal diversity is greatest at the beginning and end of the LGM, with members of the genera Pyrgo, Quinqueloculina, and Triloculina conspicuously in low abundance. These miliolid genera, which are high-Mg calcite, dominate the middle of the LGM, together comprising as much as 95 percent of the benthic assemblage. Today, this sort of association is common in high salinity environments such as the Persian Gulf. Tritium measurements have implicated the input of warm, salty shelf waters as an important ventilation source for the modern basin. This mechanism may have helped maintain deep oxygen levels during the LGM when the basin was more restricted and the climate more arid than today.

  5. Benthic remineralisation rates in southern North Sea - from point measurements to areal estimates

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    The southern North Sea is enclosed by densely populated hinterland with intensive use by agriculture and industry and thus substantially affected by anthropogenic influences. As a coastal subsystem, this applies especially to the German Wadden Sea, a system of back-barrier tidal flats along the whole German Bight. Ongoing efforts to implement environmental protection policies during the last decades changed the significance of various pollutants such as reactive nitrogen or phosphate, which raises the desire for constant monitoring of the coastal ecosystem to assess the efficiency of the employed environmental protection measures. Environmental monitoring is limited to point measurements which thus have to be interpolated with appropriate models. However, existing models to estimate various sediment characteristics for the interpolation of point measurements appear insufficient when compared with actual field measurements in the southern North Sea. We therefore seek to improve these models by identifying and quantifying key variables of benthic solute fluxes by comprehensive measurements which cover the complete spatial and seasonal variability. We employ in-situ measurements with the eddy-correlation technique and flux chambers in combination with ex-situ incubations of sediment cores to establish benthic fluxes of oxygen and nutrients. Additional ex-situ measurements determine basic sediment characteristics such as permeability, volumetric reaction rates, and substrate concentration. With our first results we mapped the distribution of measured sediment permeability, which suggest that areas with water depth greater than 30 m are impervious whereas sediment in shallower water at the Dogger Bank and along the coast is substantially permeable with permeability between 10-12 m2 and 10-10 m2. This implies that benthic fluxes can be estimated with simple diffusion-type models for water depths >30 m, whereas estimates especially for coastal sediments require percolation modelling. We are further able to estimate sediment permeability and volumetric oxygen consumption rate on the basis of grain size distribution. Since grain size distribution is already mapped with high spatial resolution, we now have the prerequisites to interpolate two key variables for benthic consumption and influx of oxygen. With our next step we intend to assess model-based estimates of benthic oxygen and nutrient fluxes with our in-situ measurements as references to refine the underlying models. Our field measurements contribute to the NOAH project (North Sea; Observation and Assessment of Habitats), the established methods for routine monitoring contribute to the WiMO project (Wissenschaftliches Monitoring / Scientific Monitoring).

  6. Responses of benthic fish exposed to contaminants in outdoor microcosms--examining the ecological relevance of previous laboratory toxicity tests.

    PubMed

    Hopkins, W A; Staub, B P; Snodgrass, J W; Taylor, B E; DeBiase, A E; Roe, J H; Jackson, B P; Congdon, J D

    2004-05-28

    Previous laboratory studies indicate that coal combustion wastes (a mixture composed of fly ash and other lower volume wastes such as bottom ash; hereafter collectively referred to as ash) adversely affect the health of benthic fish (Erimyzon sucetta; lake chubsucker), but fish in these studies were provided with ample uncontaminated food resources. Because aquatic disposal of ash can also adversely affect food resources for benthic fish, we hypothesized that changes in resources might exacerbate the effects of ash on fish observed in laboratory studies. We exposed juvenile E. sucetta in outdoor microcosms to water, sediment, and benthic resources from an ash-contaminated site or a reference site for 45 days and compared our findings to previous laboratory studies. Benthic invertebrate biomass was nearly three times greater in controls compared to ash microcosms. Total organic content of control sediment (41%) was also greater than in ash sediments (17%), suggesting that additional benthic resources may have also been limited in ash microcosms. Benthic invertebrates isolated from the ash microcosms had trace element concentrations (As, Cd, Co, Cr, Cs, Se, Sr, and V) up to 18 times higher than in weathered ash used in laboratory studies. The concentrations of trace elements accumulated by fish reflected the high dietary concentrations encountered in the ash microcosms and were associated with reduced growth (final mass = 0.07 g) and survival (25%) compared to controls (0.37 g and 67%, respectively). Accumulation of trace elements, as well as reductions in growth and survival, were more pronounced than in previous laboratory studies, suggesting that resource conditions may be important in mediating ash toxicity. Taken together, our studies suggest that ash discharge into aquatic systems is a more serious threat to the health of benthic fish than previously predicted based upon laboratory toxicity tests. PMID:15110465

  7. Phytodetritus entering the benthic boundary layer and aggregated on the sea floor in the abyssal NE Pacific

    Microsoft Academic Search

    Stace E. Beaulieu; Kenneth L. Smith Jr.

    1998-01-01

    Phytodetritus, which can originate in surface waters following seasonal phytoplankton blooms, is considered to be an important food resource for abyssal fauna. We analyzed the composition of phytodetritus sampled discretely in situ at an abyssal station in the NE Pacific. The phytodetritus was collected during two time periods straddling a seasonal maximum in the flux of particulate matter into a

  8. Chapter 5 Flocculation processes in concentrated benthic suspension (CBS) layer using a laboratory diffusive turbulent grid tank

    Microsoft Academic Search

    Nicolas Gratiot; Andrew J. Manning

    2008-01-01

    Flocculation of suspended cohesive matter can significantly alter the sediment transport patterns throughout an estuary. Estuarine floc characteristics vary both temporally and spatially. It is recognised that turbulent shear generated within the water column has an influence on their properties; however, very little is understood about the extent to which turbulence affects the structure of an individual floc population. The

  9. Imaging the water column using sediment echosounder, ADCP and multibeam echosounder - new possibilities for sedimentological, biological and oceanographic studies

    NASA Astrophysics Data System (ADS)

    Preu, B.; Spiess, V.; Schwenk, T.; Haberkern, J.; Bergmann, F.; Max, L.; Iversen, M.; Fischer, G.; Hanebuth, T.; Krastel, S.; Hernández-Molina, F.; Schneider, R. R.

    2011-12-01

    Detection and characterization of nepheloid layers, which are often bound to water mass interfaces, and benthic boundary layers are today mostly restricted to sampling and optical measurements allowing quantification of particles at one single location. However, spatial analysis of the lateral variability of suspension clouds would offer remarkable new insight into the dynamics of large scale marine sediment dispersal systems. The understanding of along-slope and down-slope sedimentary processes and their deposits could be significantly improved by mapping of particle layers. Additionally, mapping of particle clouds in time and space would allow inferring on plankton concentrations and their migration in the water column, which would improve the understanding of the biological pump. Whereas spatial measurements using sampling and optical methods are time intensive and therefore, hard to accomplish, new developments in hull-mounted high-resolution hydro-acoustic instruments allow to store and process acoustic data, imaging the water column and thereby offer an easy and time saving alternative. We will present preliminary results of an integrated acoustic approach to image and analyze nepheloid layers and comparable particle clouds. We collected multiple hydro-acoustic data sets including 18 kHz echosounder (PARASOUND) and both 38 and 75 kHz ADCP (RD INSTRUMENTS) data in current controlled and high accumulating sedimentary regimes. Additionally, multibeam echosounder measurements including water column imaging were carried out using the new EM 122 (KONGSBERG). First, we present data off SE-Africa linking the oceanographic and sedimentological framework, in particular the impact of a lee eddy in the source region of the Agulhas Current on contouritic deposits. Secondly, data collected off Mauritania are used to determine the sensitivity of 18, 38 and 75 kHz to particle sizes in relation to optical estimated concentrations. Further, the vertical plankton migration is analyzed during day and night cycles. Thirdly, we show water column data recorded off Galicia using the EM122 multibeam echosounder and will present preliminary estimations on data quality and potential for further analysis. Similar studies are conducted using data collected off northern Argentina/Uruguay and in the Gulf of Cadiz. We will present an overview about all studies to demonstrate that nepheloid layers are frequently triggered and distributed along water mass interfaces due to density contrasts and associated processes (internal waves, tidals, etc). Indirect detection by hydro-acoustic methods would open a new important research field for decoding variability of waters masses and offer new tools for future multidisciplinary research enhancing our understanding of sedimentological, biological and oceanographic processes.

  10. Benthic algae as monitors of heavy metals in various polluted rivers by Energy Dispersive X-Ray Spectrometer.

    PubMed

    Lai, Sheue-Duan; Chen, Pei-Chung; Hsu, Hoang-Kao

    2003-05-01

    Benthic microalgae assemblages were used as monitors of copper (Cu), zinc (Zn), and chromium (Cr) in various polluted rivers of San-Yeh-Kong, in southern Taiwan, and analyzed using Scanning Electron Microscope and Energy Dispersive X-Ray Spectrometer (SEM-EDS). Under SEM-EDS, the benthic algae from seriously polluted rivers (dominant by the cyanobacteria Oscillatoria chalybea, green algae Euglena acus and diatom Nitzschia palea under light microscopes) revealed the elemental compositions of heavy metals such as Cu, Zn, Cr, Ti, and that of Mg, Al, Si, P, S, Cl, K, Ca, and Fe. In contrast, benthic algae from moderately (dominant by diatoms Cymbella turgidula and Gomphonema globiferm) and lightly polluted river (dominant by diatom Diatoma vulgare) didn't have any heavy metal elements. In addition to the algal samples, unfiltered water and bottom mud were also investigated for comparison. Further experiment involving the benthic algae from seriously polluted station revealed that all dominant species could survive on the 1 mL 60 ppm Cu, 1 mL 60 ppm Zn, and 1 mL 60 ppm Cr separately after five days culture. The data of this preliminary study are sufficient to encourage further experimentation into the potential for detecting benthic algae as a bioindicator under SEM-EDS to provide rapid information about water pollution. PMID:12744437

  11. HABITAT-SPECIFIC FORAGING AND SEX DETERMINE MERCURY CONCENTRATIONS IN SYMPATRIC BENTHIC AND LIMNETIC ECOTYPES OF THE THREESPINE STICKLEBACK

    PubMed Central

    Willacker, James J.; Von Hippel, Frank A.; Ackerly, Kerri L.; O’Hara, Todd M.

    2013-01-01

    Mercury (Hg) is a widespread environmental contaminant known for the neurotoxicity of its methylated forms, especially monomethylmercury, which bioaccumulates and biomagnifies in aquatic food webs. Mercury bioaccumulation and biomagnification rates are known to vary among species utilizing different food webs (benthic vs limnetic) within and between systems. The authors assessed whether carbon and nitrogen stable isotope values and total Hg (THg) concentrations differed between sympatric benthic and limnetic ecotypes and sexes of threespine stickleback fish (Gasterosteus aculeatus) from Benka Lake, Alaska, USA. The mean THg concentration in the limnetic ecotype was significantly higher (26 mg/kg dry wt, 16.1%) than that of the benthic ecotype. Trophic position and benthic carbon percentage utilized were both important determinants of THg concentration; however, the 2 variables were of approximately equal importance in females, whereas trophic position clearly explained more of the variance than benthic carbon percentage in males. Additionally, strong sex effects (45 mg/kg dry wt, 29.4%) were observed in both ecotypes, with female fish having lower THg concentrations than males. These results indicate that trophic ecology and sex are both important determinants of Hg contamination even within a single species and lake and likely play a role in governing Hg concentrations in higher trophic levels. PMID:23456641

  12. Connections Transport Layer

    E-print Network

    Ramkumar, Mahalingam

    layer Processes - application layer Could be connection oriented or connectionless Example - TCP, connection oriented UDP - connectionless Ramkumar TL #12;Services Connections TCP UDP Connection Oriented

  13. Flow effects on benthic stream invertebrates and ecological processes

    NASA Astrophysics Data System (ADS)

    Koprivsek, Maja; Brilly, Mitja

    2010-05-01

    Flow is the main abiotic factor in the streams. Flow affects the organisms in many direct and indirect ways. The organisms are directly affected by various hydrodynamic forces and mass transfer processes like drag forces, drift, shear stress, food and gases supply and washing metabolites away. Indirect effects on the organisms are determining and distribution of the particle size and structure of the substrate and determining the morphology of riverbeds. Flow does not affect only on individual organism, but also on many ecological effects. To expose just the most important: dispersal of the organisms, habitat use, resource acquisition, competition and predator-prey interactions. Stream invertebrates are adapted to the various flow conditions in many kinds of way. Some of them are avoiding the high flow with living in a hyporeic zone, while the others are adapted to flow with physical adaptations (the way of feeding, respiration, osmoregulation and resistance to draught), morphological adaptations (dorsoventrally flattened shape of organism, streamlined shape of organism, heterogeneous suckers, silk, claws, swimming hair, bristles and ballast gravel) or with behaviour. As the flow characteristics in a particular stream vary over a broad range of space and time scales, it is necessary to measure accurately the velocity in places where the organisms are present to determine the actual impact of flow on aquatic organisms. By measuring the mean flow at individual vertical in a single cross-section, we cannot get any information about the velocity situation close to the bottom of the riverbed where the stream invertebrates are living. Just measuring the velocity near the bottom is a major problem, as technologies for measuring the velocity and flow of natural watercourses is not adapted to measure so close to the bottom. New researches in the last two decades has shown that the thickness of laminar border layer of stones in the stream is only a few 100 micrometers, what is not enough to make a shelter for stream invertebrates. It serves as a shelter only for microorganisms, but the stream invertebrates have to avoid the swift flow or adapt to flow with adaptations described above. To understand what conditions are subject to aquatic organisms and how to adapt, it is essential. Both, knowledge of fluid dynamics in natural watercourses and ecology are needed to understand to what conditions the stream invertebrates are exposed and how they cope with them. Some investigations of near bed flow will be performed on the Glinšica stream. The acoustic Doppler velocimeter SonTek will be adapted to measure so close to the bed as possible. It is expected we should be able to measure the velocities just 0,5 cm above the bed surface. We intend to measure the velocities on a natural and on a regulated reach and then compare the results.

  14. Decreased trophic position as a function of increasing body size of a benthic omnivorous fish from the largest freshwater lake in China

    Microsoft Academic Search

    Yuyu Wang; Xiubo Yu; Jun Xu

    2011-01-01

    Potential body size-trophic position relationships of the Darkbarbel catfish Pelteobagrus vachelli (Richardson 1846) were examined using stable isotope analysis. Pelteobagrus vachelli is a benthic feeding fish from Lake Poyang, the largest freshwater lake in China. Two-source mixing model with mussel (Corbicula fluminea) and snail (Bellamya aeruginosa) as baseline primary consumers of planktonic and benthic food webs, respectively, was used to

  15. RESPONSE OF BENTHIC ECOSYSTEMS TO DEEP OCEAN SEWAGE OUTFALLS IN HAWAII: A NUTRIENT CYCLING APPROACH TO BIOLOGICAL IMPACT ASSESSMENT AND MONITORING

    EPA Science Inventory

    The report describes the nutrient budgets, benthic metabolism and community structures observed around two deep ocean sewage outfalls off Oahu, Hawaii. The authors conclude that, at an ecosystem management level, the overall effect of effluent on benthic and pelagic ecosystems of...

  16. Organic-walled dinoflagellate cysts and benthic foraminifera in coastal sediments of the last century from the Gulf of Tehuantepec, South Pacific

    E-print Network

    Long, Bernard

    of the adjacent coastal zone. Core samples were also analyzed for benthic foraminiferal content in orderOrganic-walled dinoflagellate cysts and benthic foraminifera in coastal sediments of the last century from the Gulf of Tehuantepec, South Pacific Coast of Mexico L.F. Vásquez-Bedoya a , T. Radi b , A

  17. Oyster reef restoration in the Northern Gulf of Mexico: effect of artificial substrate and sge on nekton and benthic macroinvertebrate assemblage use

    USGS Publications Warehouse

    Brown, Laura A.; Furlong, Jessica N.; Brown, Kenneth M.; LaPeyre, Megan K.

    2013-01-01

    In the northern Gulf of Mexico (GOM), reefs built by eastern oysters, Crassostrea virginica, provide critical habitat within shallow estuaries, and recent efforts have focused on restoring reefs to benefit nekton and benthic macroinvertebrates. We compared nekton and benthic macroinvertebrate assemblages at historic, newly created (<5years) and old (>6years) shell and rock substrate reefs. Using crab traps, gill-nets, otter trawls, cast nets, and benthic macroinvertebrate collectors, 20 shallow reefs (<5m) in the northern GOM were sampled throughout the summer of 2011. We compared nekton and benthic assemblage abundance, diversity and composition across reef types. Except for benthic macroinvertebrate abundance, which was significantly higher on old rock reefs as compared to historic reefs, all reefs were similar to historic reefs, suggesting created reefs provide similar support of nekton and benthic assemblages as historic reefs. To determine refuge value of oyster structure for benthic macroinvertebrates compared to bare bottom, we tested preferences of juvenile crabs across depth and refuge complexity in the presence and absence of adult blue crabs (Callinectes sapidus). Juveniles were more likely to use deep water with predators present only when provided oyster structure. Provision of structural material to support and sustain development of benthic and mobile reef communities may be the most important factor in determining reef value to these assemblages, with biophysical characteristics related to reef location influencing assemblage patterns in areas with structure; if so, appropriately locating created reefs is critical.

  18. A comparative analysis of restoration measures and their effects on hydromorphology and benthic invertebrates in 26 central and southern European rivers

    Microsoft Academic Search

    S. C. Jähnig; K. Brabec; A. Buffagni; S. Erba; A. Lorenz; T. Ofenböck; P. F. M. Verdonschot; D. Hering

    2010-01-01

    1.?Hydromorphological river restoration usually leads to habitat diversification, but the effects on benthic invertebrates, which are frequently used to assess river ecological status, are minor. We compared the effects of river restoration on morphology and benthic invertebrates by investigating 26 pairs of non-restored and restored sections of rivers in Austria, Czech Republic, Germany, Italy and the Netherlands. 2.? Sites were

  19. Mixed layer warming-deepening in the Mediterranean Sea and its effect on the marine environment

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    This work aims at investigating the evolution of the ocean mixed layer in the Mediterranean Sea and linking it to the occurrence of mass mortalities of benthic invertebrates. The temporal evolution of selected parameters describing the mixed layer and the seasonal thermocline is provided for the whole Mediterranean Sea for spring, summer and autumn and for the period 1945-2011. For this analysis all temperature profiles collected in the basin with bottles, Mechanical Bathy-Thermographs (MBT), eXpendable Bathy-Thermographs (XBT), and Conductivity-Temperature-Depth (CTD) have been used (166,990). These data have been extracted from three public sources: the MEDAR-MEDATLAS, the World Ocean Database 2013 and the MFS-VOS program. Five different methods for estimating the mixed layer depth are compared using temperature profiles collected at the DYFAMED station in the Ligurian Sea and one method, the so-called three-segment method, has been selected for a systematic analysis of the evolution of the uppermost part of the whole Mediterranean Sea. This method approximates the upper water column with three segments representing mixed layer, thermocline and deep layer and has shown to be the most suitable method for capturing the mixed layer depth for most shapes of temperature profiles. Mass mortalities events of benthic invertebrates have been identified by an extensive search of all data bases in ISI Web of Knowledge considering studies published from 1945 to 2011. Studies reporting the geographical coordinates, the timing of the events, the species involved and the depth at which signs of stress occurred have been considered. Results show a general increase of thickness and temperature of the mixed layer, deepening and cooling of the thermocline base in summer and autumn. Possible impacts of these changes are mass mortalities events of benthic invertebrates that have been documented since 1983 mainly in summer and autumn. It is also shown that most mass mortalities occurred in months with anomalously high mixed layer depth temperature leading to the conclusion that warming of upper Mediterranean Sea has allowed interannual temperature variability to reach environmental conditions beyond the thermal tolerance of some species.

  20. Benthic control on the statistical distribution of transported sediment carbon in a low-gradient stream

    NASA Astrophysics Data System (ADS)

    Ford, William I.; Fox, James F.

    2014-07-01

    Results from a numerical model that simulates particulate organic carbon source, fate and transport were used to generate the statistical distribution of transported sediment carbon in a low-gradient, agriculturally-impacted stream over a five-year model simulation. Results suggest that the statistical distribution of transported sediment carbon is Gamma distributed (RMSEA = 0.066) for the low-gradient stream. The distributional form of transported sediment carbon is governed by seasonal variability of temporarily stored benthic carbon and the relative contributions of benthic, bank and upland carbon sources. Results of the study suggest that shape and skew of the Gamma distribution are governed by biological activity (i.e., autochthonous production and decomposition) of the streambed. Analysis was performed to examine how field sampling factors, including flow conditions during sampling, sampling frequency, and the sampling temporal domain including event, seasonal and annual variability, capture the statistical distribution of transported sediment carbon. Contrary to conventional wisdom, sampling flow conditions and sampling frequency showed little impact on the sampled distribution of transported sediment carbon, which reflects the amalgamation of streambank and upland carbon sources on the stream bed in this low-gradient stream. Annual variability, i.e., wet and dry years, and seasonal variability were needed to adequately capture the statistical distribution of transported sediment carbon, which reflects the stochastic nature of the hydrologic regime annually and the seasonal variability of biological processes. The results provide a testable hypothesis, and a sampling design approach, for the statistical distribution of transported sediment carbon in low-gradient systems where benthic biological processes are prominent.