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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

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.

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

1995-02-01

3

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

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

4

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

PubMed Central

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

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

2014-01-01

5

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

NASA Astrophysics Data System (ADS)

In the southern basin of Lake Lugano, thermal stratification of the water column during summer and autumn leads to a lack of exchange between surface and deep water masses, and consequently to seasonal bottom water anoxia, associated with high methane concentrations. With the onset of bottom water anoxia, a dense layer of high particulate matter concentration - a so-called benthic nepheloid layer (BNL) - develops in the bottom waters. A sharp redox gradient marks the upper boundary of the BNL. At its maximum, the BNL extends 15 - 30 m from the sediment into the water column. We investigated the identity of the BNL and key environmental factors controlling its formation in the framework of a seasonal study. Compound specific C-isotope measurements and Fluorescence In Situ Hybridisation (FISH) of suspended particulate organic matter, radioactive tracer based measurements of methane oxidation, as well as investigation of geochemical water column parameters were performed in spring and autumn. Our analyses revealed that the microbial biomass within the BNL is dominated by methanotrophic bacteria. Aerobic methane oxidation (MOx) was restricted to a narrow zone at the top of the BNL, reaching maximum rates of up to 1.8 ?M/day. The rates of MOx activity effectively consumed most (>99%) of the uprising methane, leading to the formation of a sharp CH4 concentration gradient and a strongly suppressed kinetic isotope effect (? = -2.8o). CH4 oxidation was limited by the diffusive supply of O2 from the upper hypolimnion, implying that methanotrophy is the primary driver of the seasonal expansion of the anoxic bottom water volume, and explaining the vertical migration of the BNL in response to its own O2 consumption. The bulk organic matter extracted from the BNL was strongly depleted in 13C (?13C < -60o), providing evidence for the incorporation of CH4-derived carbon into the biomass, suggesting that the BNL was composed of MOx-communities. This was further evidenced by four dominant fatty acid biomarkers (C16:1?5, C16:1?6, C16:1?7, and C16:1?8), which were strongly C-isotopically depleted, with ?13C values between -62o (?6) and -80o (?7). The fingerprint of isotopically depleted FAs indicates a dominance of Type I MOx bacteria in the BNL, which we could confirm with FISH using specific probes. Isotope mixing considerations suggest that 77 - 96 % of fatty acid carbon in the BNL is CH4-derived. FISH revealed that up to 30% of microbial cells in the BNL are methanotrophic. The cell size of methanotrophs was significantly larger than of other microbial cells, and an independent approach to quantify the contribution of methanotroph-carbon to the BNL biomass, based on methanotrophic cell size, confirmed our C-isotope-based estimate.

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

2014-05-01

6

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

USGS Publications Warehouse

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

Shideler, G.L.

1981-01-01

7

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

E-print Network

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

Boss, Emmanuel S.

8

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

E-print Network

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

Boss, Emmanuel S.

9

Nepheloid layers and internal waves over continental shelves and slopes  

USGS Publications Warehouse

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.

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

1986-01-01

10

Nepheloid layers origin and development in the nazaré canyon eustrataform project  

NASA Astrophysics Data System (ADS)

In the frame of EUSTRATAFORM project was conducted a general hydrographic and nephelometric survey in the Nazaré canyon (Portuguese continental shelf), under winter conditions. Discrete measurements include CTD, turbidity, sampling of water-sediment interface, concentration of particles and estimation of grain-size distribution. A sampling grid throws the canyon axis and head was visited, allowing visualizing the nepheloid layers distribution. In this study the evaluation of optical and mineralogical proprieties of suspended matter and the interpretation of this variation in a physical and geological context will be presented.

Oliveira, A.; Vitorino, J.; Rodrigues, A.

2003-04-01

11

Near-Inertial Internal Waves: a Mechanism to Maintain a Permanent Bottom Nepheloid Layer on the Ebro Shelf (Northwestern Mediterranean)  

NASA Astrophysics Data System (ADS)

In the Ebro delta continental shelf activity of near-inertial waves (17 h period) was recorded by a current meter with turbidimeter deployed 5 m above the bottom at 60 m depth. Between 60 m depth and the shelf break this shelf has very gentle slopes of 0.1° or less and coincides with the range of estimated angles of propagation of near-inertial internal waves energy of this region (? ; from 0.05 to 0.15°). Data from a closely-spaced grid of CTD+T+F stations in the Ebro shelf show a permanent bottom nepheloid layer extending from about 50-60 m depth to the shelf break, coinciding with the zone where the shelf gradient fits with ? . The development of this mid-to-outer shelf nepheloid layer maintains similar during the year independently from storms and river avenues events and can remain isolated within or underneath the thermocline. These facts suggest that the repetitive action of near-inertial internal waves maintain this mid-to-outer shelf nepheloid layer during the year. Internal waves could contribute to distribute and maintain suspended sediment near the bottom in the mid and outer part of the Ebro shelf. This mechanism could be affecting other Mediterranean continental shelves and could explain similar nepheloid layer distributions found in other Mediterranean prodeltaic systems.

Palanques, A.; Puig, P.; Guillen, J.

2002-12-01

12

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

NASA Astrophysics Data System (ADS)

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

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

2008-08-01

13

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

USGS Publications Warehouse

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

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

2008-01-01

14

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

NASA Astrophysics Data System (ADS)

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

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

2010-12-01

15

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)

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.

Gadel, François; Charrière, Bruno; Serve, Léon

1993-09-01

16

Benthic boundary layer processes in the Lower Florida Keys  

USGS Publications Warehouse

This special issue of Geo-Marine Letters, "Benthic Boundary Layer Processes in the Lower Florida Keys," includes 12 papers that present preliminary results from the Key West Campaign. The Dry Tortugas and Marquesas Keys test sites were selected by a group of 115 scientists and technicians to study benthic boundary layer processes in a carbonate environment controlled by bioturbation and biogeochemical processes. Major activities included remote sediment classification; high-frequency acoustic scattering experiments; sediment sampling for radiological, geotechnical, biological, biogeochemical, physical, and geoacoustic studies; and hydrodynamic studies using an instrumented tetrapod. All these data are being used to improve our understanding of the effects of environmental processes on sediment structure and behavior.

Lavoie, D.L.; Richardson, M.D.; Holmes, C.

1997-01-01

17

On the links between a river’s hyperpycnal plume and marine benthic nepheloid layer in the wake of a typhoon  

NASA Astrophysics Data System (ADS)

In 2010 two moorings each configured with a CTD and an ADCP, one with an additional non-sequential sediment trap (NSST), were deployed in the head region of the Gaoping Submarine Canyon 3 days after the typhoon-induced peaks of the runoff and suspended sediment concentration (SSC) of the Gaoping River in southern Taiwan. Our data show a demarcation between tidal and hyperpycnal regimes in the temperature, salinity, and flow fields. The latter existed in the first 5 days out of the 18-day deployment, as defined by higher water density due to high SSC. Several lines of evidence indicate the presence of the tail end of a hyperpycnal turbidity current (HTC), including the retention of warm water near the canyon floor, high SSC, down-canyon directed residual flow and its vertical structure, and high terrestrial fraction (larger than 70%) of the organic particles carried by the flow. The decreasing mass flux during the deployment is also an indication of a waning HTC. Our findings also show that the vertical flow structure and the direction of the gravity-driven down-canyon HTC were retarded by the instantaneous up-canyon-directed tidal oscillations in the submarine canyon.

Hsu, Ray T.; Liu, James T.; Su, Chih-Chieh; Kao, Shuh-Ji; Chen, Shih-Nan; Kuo, Fang-Hsu; Huang, Jeff C.

2014-09-01

18

ANALYTICAL AND EXPERIMENTAL STUDIES OF THE BENTHIC BOUNDARY LAYER AND THEIR APPLICABILITY TO NEAR-BOTTOM TRANSPORT IN LAKE ERIE  

EPA Science Inventory

With there being few if any well organized field experiments in Lake Erie on benthic boundary layer (BBL) physics to review, this paper summarizes theoretical and experimental observations from the ocean, estuary, and continental shelf research, contrasts the Lake Erie setting wi...

19

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

USGS Publications Warehouse

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

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

1986-01-01

20

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

NASA Astrophysics Data System (ADS)

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.

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

2014-08-01

21

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

NASA Technical Reports Server (NTRS)

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

Frewing, K.

1980-01-01

22

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

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

Joan E. Cartes

1998-01-01

23

Benthic Cyanobacterial Mats in the High Arctic: Multi-Layer Structure and Fluorescence Responses to Osmotic Stress  

PubMed Central

Cyanobacterial mats are often a major biological component of extreme aquatic ecosystems, and in polar lakes and streams they may account for the dominant fraction of total ecosystem biomass and productivity. In this study we examined the vertical structure and physiology of Arctic microbial mats relative to the question of how these communities may respond to ongoing environmental change. The mats were sampled from Ward Hunt Lake (83°5.297?N, 74°9.985?W) at the northern coast of Arctic Canada, and were composed of three visibly distinct layers. Microsensor profiling showed that there were strong gradients in oxygen within each layer, with an overall decrease from 100% saturation at the mat surface to 0%, at the bottom, accompanied by an increase of 0.6 pH units down the profile. Gene clone libraries (16S rRNA) revealed the presence of Oscillatorian sequences throughout the mat, while Nostoc related species dominated the two upper layers, and Nostocales and Synechococcales sequences were common in the bottom layer. High performance liquid chromatography analyses showed a parallel gradient in pigments, from high concentrations of UV-screening scytonemin in the upper layer to increasing zeaxanthin and myxoxanthin in the bottom layer, and an overall shift from photoprotective to photosynthetic carotenoids down the profile. Climate change is likely to be accompanied by lake level fluctuations and evaporative concentration of salts, and thus increased osmotic stress of the littoral mat communities. To assess the cellular capacity to tolerate increasing osmolarity on physiology and cell membrane integrity, mat sections were exposed to a gradient of increasing salinities, and PAM measurements of in vivo chlorophyll fluorescence were made to assess changes in maximum quantum yield. The results showed that the mats were tolerant of up to a 46-fold increase in salinity. These features imply that cyanobacterial mats are resilient to ongoing climate change, and that in the absence of major biological perturbations, these vertically structured communities will continue to be a prominent feature of polar aquatic ecosystems. PMID:22557996

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

2012-01-01

24

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)

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.

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

2014-01-01

25

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

E-print Network

(%/m) 50 (B) 60 70 The SPM concentrations from the October 1980 water samples were excluded in the conversion due to plastic container contamination which resulted in a scattering of the data. This contamination error... indicative of attenuation by suspended material and the water itself. The 25 cm pathlength distance also allows optimum recording precision in the SPM concentration range of the Flower Garden region. The PHISH also contains two, 5 1 Niskin bottles...

Cecil, Thomas Martin

2012-06-07

26

Benthic Invertebrate Biomonitoring  

NSDL National Science Digital Library

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.

1999-01-01

27

An autonomous benthic lander  

Microsoft Academic Search

A new, multi-purpose autonomous benthic lander is described, and preliminary experimental data are presented relating to deployments in the Atlantic Frontier (eastern north Atlantic) during the recent UK Thematic Programme ‘BENBO’. The autonomous lander was deployed at two contrasting sites — Site A (mouth of Rockall Trough; 3570m) and Site B (Hatton-Rockall Bank; 1100m) — before and following the spring-time

Kevin S Black; Gary R Fones; Oli C Peppe; Hilary A Kennedy; Ilhem Bentaleb

2001-01-01

28

The Three-Parameter Model of the Submarine Light Field: Radiant Energy Absorption and Energy Trapping in Nepheloid Layers  

Microsoft Academic Search

The three-parameter model of the submarine light field is here proposed. The model consists of three ph_ysical parameters: the scalar irradiance (Eo), downwelling vector irradiance (Ez), and average cosine (\\/x) of the submarine light field. This model is derived from a general exponential decay equation that is valid for all submarine light fields free of horizontal divergence. From the exponential

Robert Hans Stavn

1982-01-01

29

Marine chemical ecology in benthic environments.  

PubMed

This review covers the recent marine chemical ecology literature for benthic bacteria and cyanobacteria, macroalgae, sponges, cnidarians, molluscs, other benthic invertebrates, and fish. PMID:25070776

Puglisi, Melany P; Sneed, Jennifer M; Sharp, Koty H; Ritson-Williams, Raphael; Paul, Valerie J

2014-11-01

30

Benthic-Pelagic coupling in the Black Sea northwestern shelf  

NASA Astrophysics Data System (ADS)

A new approach for modeling the benthic compartment in 3D ocean models is applied to analyze the benthic-pelagic coupling in the Black Sea northwestern shelf (BS-NWS) and to review the contribution of sedimentary diagenesis to the BS-NWS biogeochemical cycles (nitrogen, oxygen and carbon). This approach combines an explicit representation of sediment organic matter deposition and resuspension, controlled by the bottom shear stress, and a parameterization of mineralization pathways control by bottom environmental properties. The model reproduces the magnitude and inter-regional and seasonal variability depicted by in situ benthic fluxes estimates obtained by benthic chambers and sediment cores incubations. The model illustrates how this observed variability results from both variable sedimentation rate and variable diagenetic pathways in the sediment layer. Three distinct areas are identified based on the analysis of the simulated seasonal cycle of bottom environmental conditions, benthic-pelagic fluxes and diagenetic processes. These areas extend along a gradient from the land-ocean interface to the open sea boundary and are each characterized by a particular diagenetic pathway, in a way similar as they succeed vertically in a sediment profile. (1) In the hypoxic zone, high remineralization rates lead to a seasonal peak in anoxic diagenesis and under certain conditions to hydrogen sulphide effluxes from the sediment, (2) in the denitrification zone, benthic denitrification rates are maximal and (3) in the oxic zone, where organic matter accumulation are low, oxic diagenesis prevails and seasonality is less marked. This study underlines that representing resuspension and deposition processes in coupled benthic-pelagic models is essential to realistically describe the horizontal distribution of benthic-pelagic fluxes and the export from the shelf region to the deep sea.

Capet, Arthur; Akoumianaki, Ionna; Meysman, Filip; Soetaert, Karline; Grégoire, Marilaure

2014-05-01

31

Sediment Diagenesis and Benthic Flux  

E-print Network

and the resulting fluxes across the sediment­water interface influence the global carbon cycle and the pH of the sea6.11 Sediment Diagenesis and Benthic Flux S. Emerson and J. Hedges University of Washington

Emerson, Steven R.

32

Measurements of diffusive sublayer thicknesses in the ocean by alabaster dissolution, and their implications for the measurements of benthic fluxes  

Microsoft Academic Search

Fluxes of reactive chemical species across the sediment-water interface can profoundly influence the dominant biogeochemical cycles in the worlds ocean. However, reliable in-situ measurements of benthic fluxes of many reactive species cannot be carried out without adjustments of stirring rates inside benthic flux chambers to match boundary layer conditions prevailing outside. A simple method to compare flow levels consists of

Peter H. Santschi; Robert F. Anderson; Walter Bowles

1991-01-01

33

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...

34

Layers  

NASA Astrophysics Data System (ADS)

The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states ?4( z), ?5( x), and ?5( y) to the conduction-band state ?1( s). On the basis of the relationship between PC-peak energy and temperature, the optical band gap could be well expressed by the expression E g( T) = E g(0) - 2.80 × 10-4 T 2/(287 + T), where E g(0) was estimated to be 3.7920 eV, 3.7955 eV, and 3.8354 eV for the valence-band states ?4( z), ?5( x), and ?5( y), respectively. Results from PC spectroscopy revealed the crystal-field and spin-orbit splitting were 3.5 meV and 39.9 meV. The gradual decrease of PC intensity with decreasing temperature can be explained on the basis of trapping centers associated with native defects in the MnAl2S4 layers. Plots of log J ph, the PC current density, against 1/ T, revealed a dominant trap level in the high-temperature region. By comparing PC and the Hall effect results, we confirmed that this trap level is a shallow donor 18.9 meV below the conduction band.

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

2014-09-01

35

Benthic phosphorus regeneration in the Potomac River Estuary  

USGS Publications Warehouse

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.

Callender, E.

1982-01-01

36

Intercalibration of benthic flux chambers I. Accuracy of flux measurements and influence of chamber hydrodynamics  

Microsoft Academic Search

The hydrodynamic properties and the capability to measure sediment–water solute fluxes, at assumed steady state conditions, were compared for three radically different benthic chamber designs: the “Microcosm”, the “Mississippi” and the “Göteborg” chambers. The hydrodynamic properties were characterized by mounting a PVC bottom in each chamber and measuring mixing time, diffusive boundary layer thickness (DBL thickness) shear velocity (u?), and

A. Tengberg; H. Stahl; G. Gust; V. Müller; U. Arning; H. Andersson; P. O. J. Hall

2004-01-01

37

BENTHIC MACROFAUNAL ALIENS IN WILLAPA BAY  

EPA Science Inventory

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

38

Feasibility of remote sensing benthic microalgae  

NASA Technical Reports Server (NTRS)

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

Zingmark, R. G.

1979-01-01

39

Benthic respiration measured by total carbonate production  

Microsoft Academic Search

Abstract The suitability of total carbonate production,instead of oxygen consumption,as a measure,of benthic respiration has been investigated. In situ fluxes of total carbonate, oxygen, calcium, total alkalinity, nutrients, and sulfide across the sediment-water interface were measured in diver- operated benthic flux chambers. Two chambers,were run in parallel to test the influence of oxygen and pH levels on total carbonate production.

LEIF G. ANDERSON; PER O. J. HALL; ÅKE IVERFELDT; MICHIEL M. RUTGERS VAN DER LOEFF; BJØRN SUNDBY; STIG F. G. WESTERLUND

1986-01-01

40

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

EPA Science Inventory

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

41

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

NASA Astrophysics Data System (ADS)

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.

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

2012-12-01

42

Early diagenesis and nutrient benthic fluxes in the Adriatic Sea  

NASA Astrophysics Data System (ADS)

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.

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

2003-04-01

43

Ultrastructural features of the benthic dinoflagellate Ostreopsis cf. ovata (Dinophyceae).  

PubMed

The toxic benthic dinoflagellate Ostreopsis cf. ovata has considerably expanded its distribution range in the last decade, posing risks to human health. Several aspects of this species are still poorly known. We studied ultrastructural features of cultivated and natural populations of Ostreopsis cf. ovata from the Gulf of Naples (Mediterranean Sea) using confocal laser scanning, and scanning and transmission electron microscopy. New information on the morphology and location of several sulcal plates was gained and a new plate designation is suggested that better fits the one applied to other Gonyaulacales. The microtubular component of the cytoskeleton, revealed using an anti-?-tubulin antibody, consisted of a cortical layer of microtubules arranged asymmetrically in the episome and in the hyposome, complemented by a complex inner microtubular system running from the sulcal area towards the internal part of the cell. The conspicuous canal was delimited by two thick, burin-shaped lobes ending in a tubular ventral opening. The canal was surrounded by mucocysts discharging their content into it. A similar structure has been reported in other benthic and planktonic dinoflagellates and may be interpreted as an example of convergent evolution in species producing large amounts of mucus. PMID:24742926

Escalera, Laura; Benvenuto, Giovanna; Scalco, Eleonora; Zingone, Adriana; Montresor, Marina

2014-05-01

44

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

45

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

E-print Network

Abstract 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...

Esson, Diane; Wood, Susanna A; Packer, Michael A

2011-07-18

46

Benthic community structure of the Bosphorus and surrounding area.  

PubMed

Abstract Spatial and temporal distribution of benthic communities around the Strait of Istanbul (Bosphorus) and the effect of lower layer discharge on these communities have been evaluated during studies between February-December 1999. Mytilus galloprovincialis was the dominant species with fasies at the Black Sea station that is not affected by the strait lower layer current system. On the other hand, another Black Sea station, influenced by the strait lower layer currents, has a similar biota to the strait stations. Species richness and diversity is highest in the strait than other areas. The dominant species is Maera grossimana. However, the station located at the Black Sea exit of the strait has a different biota, and various groups/species appeared to be dominant. Melinna palmata is the dominant species at the Sea of Marmara during the study period. Low dissolved oxygen values of lower layer and soft substratum of sediment resulted in wide distribution of Melinna palmata, adapted to these conditions. The closer stations to the strait in the Sea of Marmara have higher diversity as a result of hydrodynamic processes. On the other hand, coastal stations with low currents and inputs have lower index values, showing the negative effect of discharges and pollution. PMID:12420963

Uysal, A; Yüksek, A; Oku?, E; Yilmaz, N

2002-01-01

47

REMOTE SENSING OF BENTHIC HABITATS IN SOUTHWESTERN  

E-print Network

that are underground, underwater, or embedded in the human body." Core Academic Partners: · Northeastern University.gilbes@upr.edu #12;Center for Subsurface Sensing and Imaging Systems (CenSSIS) Mission: "to revolutionize? The term benthic refers to anything associated with or occurring on the bottom of a body of water

Gilbes, Fernando

48

Benthic macroinvertebrates in seven New Zealand lakes  

Microsoft Academic Search

The benthic macroinvertebrate faunas of seven Rqtorua lakes (Okataina, Rotoma, Tikitapu, Okareka, Rotokakahi, Ngapouri, and Okaro) were investigated by Ekman dredge at monthly intervals between May 1970 and May 1971. The main groups present were molluscs, oligochaete worms, and chironomid larvae. Molluscs were absent from Tikitapu, probably because of low levels of HCO3 and Ca, and mussels were absent from

D. J. Forsyth

1978-01-01

49

Woody Vegetation Removal Stimulates Riparian and Benthic  

E-print Network

Woody Vegetation Removal Stimulates Riparian and Benthic Denitrification in Tallgrass Prairie is concentrated in riparian zones with potential impacts on biogeochemical processes there. Although the effects of woody riparian vege- tation on denitrification in both riparian soils and streams have been well studied

Dodds, Walter

50

Pacific walrus: Benthic bioturbator of Beringia  

Microsoft Academic Search

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

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

2006-01-01

51

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

NASA Astrophysics Data System (ADS)

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.

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

2013-07-01

52

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

NASA Astrophysics Data System (ADS)

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

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

2002-03-01

53

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

PubMed Central

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

2011-01-01

54

Benthic biogeochemistry beneath the Mississippi River plume  

Microsoft Academic Search

Biogeochemical processes occurring near the sediment-water interface of shallow (?20 m) water sediments lying beneath the\\u000a Mississippi River plume on the Louisiana shelf were studied using benthic chambers and sediment cores. Three sites were chosen\\u000a with distinctly different characteristics. One was overlain by oxic water where aerobic respiration dominated organic matter\\u000a remineralization. The second site was overlain by oxic water

John W. Morse; Gilbert T. Rowe

1999-01-01

55

Mechanisms of temporary adhesion in benthic animals.  

PubMed

Adhesive systems are ubiquitous in benthic animals and play a key role in diverse functions such as locomotion, food capture, mating, burrow building, and defence. For benthic animals that release adhesives, surface and material properties and external morphology have received little attention compared to the biochemical content of the adhesives. We address temporary adhesion of benthic animals from the following three structural levels: (a) the biochemical content of the adhesive secretions, (b) the micro- and mesoscopic surface geometry and material properties of the adhesive organs, and (c) the macroscopic external morphology of the adhesive organs. We show that temporary adhesion of benthic animals is affected by three structural levels: the adhesive secretions provide binding to the substratum at a molecular scale, whereas surface geometry and external morphology increase the contact area with the irregular and unpredictable profile of the substratum from micro- to macroscales. The biochemical content of the adhesive secretions differs between abiotic and biotic substrata. The biochemistry of the adhesives suitable for biotic substrata differentiates further according to whether adhesion must be activated quickly (e.g. as a defensive mechanism) or more slowly (e.g. during adhesion of parasites). De-adhesion is controlled by additional secretions, enzymes, or mechanically. Due to deformability, the adhesive organs achieve intimate contact by adapting their surface profile to the roughness of the substratum. Surface projections, namely cilia, cuticular villi, papillae, and papulae increase the contact area or penetrate through the secreted adhesive to provide direct contact with the substratum. We expect that the same three structural levels investigated here will also affect the performance of artificial adhesive systems. PMID:20233167

Dodou, D; Breedveld, P; de Winter, J C F; Dankelman, J; van Leeuwen, J L

2011-02-01

56

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

NASA Astrophysics Data System (ADS)

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.

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

57

Use of a whirling cup rotor to stir benthic chambers  

Microsoft Academic Search

Realistic stirring is an important concern when using benthic chambers to measure processes at the sediment-water column interface.\\u000a A simple whirling cup rotor device that is driven by external flow and stirs benthic chambers effectively is described here.\\u000a Flow tank studies and field studies demonstrated that this device homogenizes benthic chambers rapidly and responds quickly\\u000a and linearly to external flow

Lawrence B. Cahoon

1988-01-01

58

Benthic primary production in the Columbia River Estuary. Final report  

SciTech Connect

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.

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

1984-02-01

59

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...

60

Benthic fluxes of dissolved organic carbon in three temperate Australian estuaries: Implications for global estimates of benthic DOC fluxes  

Microsoft Academic Search

Light and dark benthic dissolved organic carbon (DOC) fluxes and sediment characteristics (total organic carbon (TOC), total nitrogen (TN), TOC isotope ratio (?13C), phospholipid fatty acid (PLFA) concentration, and compound-specific ?13C) were measured seasonally in a range of habitats in three warm-temperate Australian estuaries to determine what factors control benthic DOC fluxes. Benthic DOC fluxes were seasonal with the highest

D. T. Maher; B. D. Eyre

2010-01-01

61

Benthic fluxes of dissolved organic carbon in three temperate Australian estuaries: Implications for global estimates of benthic DOC fluxes  

NASA Astrophysics Data System (ADS)

Light and dark benthic dissolved organic carbon (DOC) fluxes and sediment characteristics (total organic carbon (TOC), total nitrogen (TN), TOC isotope ratio (?13C), phospholipid fatty acid (PLFA) concentration, and compound-specific ?13C) were measured seasonally in a range of habitats in three warm-temperate Australian estuaries to determine what factors control benthic DOC fluxes. Benthic DOC fluxes were seasonal with the highest rates generally observed during summer. Most habitats displayed uptake of DOC during the dark and efflux during the light, and were a net source of DOC to the overlying waters over the diel cycle. Macrophyte habitats (seagrass and macroalgae) had the highest benthic fluxes of DOC (up to ˜50 mmol C m-2 d-1). Organic matter supply to the sediment was dominated by in situ production, and both quantity and source exerted control over benthic DOC fluxes. DOC flux was tightly coupled to bacteria and algal PLFA concentrations during summer, and algal PLFA concentrations during winter, indicating a strong influence of microbial interactions on benthic DOC flux and a temperature-related decoupling of algae and bacteria under cooler conditions. Estimates of the global estuarine benthic DOC flux indicate that these areas are a significant source of DOC to the ocean (1-41 Tg C yr -1). Inclusion of macrophyte, salt marsh, mangrove, and intertidal benthic DOC flux estimates resulted in a higher global continental margin benthic DOC flux (106-416 Tg C yr -1) than the previous estimate (90 Tg C yr-1).

Maher, D. T.; Eyre, B. D.

2010-12-01

62

Natural Variability of Benthic Species Composition Dean Billheimer Tamre Cardoso Elizabeth Freeman  

E-print Network

Words: Biological monitoring; benthic invertebrates; spatial model; state- space model 1. Introduction. This approach is illustrated by an analysis of the composition of benthic invertebrates collected from

Washington at Seattle, University of

63

Diachronous benthic ?18O responses during late Pleistocene terminations  

NASA Astrophysics Data System (ADS)

Benthic ?18O is often used as a stratigraphic tool to place marine records on a common age model and as a proxy for the timing of ice volume/sea level change. However, Skinner and Shackleton (2005) found that the timing of benthic ?18O change at the last termination differed by 3900 years between one Atlantic site and one Pacific site. These results suggest that benthic ?18O change may not always accurately record the timing of deglaciation. We compare benthic ?18O records from 20 Atlantic sites and 14 Pacific sites to evaluate systematic differences in the timing of terminations in benthic ?18O. Analysis of sedimentation rates derived from the alignment of benthic ?18O suggests a statistically significant Atlantic lead over Pacific benthic ?18O change during the last six terminations. We estimate an average Pacific benthic ?18O lag of 1600 years for Terminations 1-5, slightly larger than the delay expected from ocean mixing rates given that most glacial meltwater probably enters the North Atlantic. We additionally find evidence of ˜4000-year Pacific ?18O lags at approximately 128 ka and 330 ka, suggesting that stratigraphic correlation of ?18O has the potential to generate age model errors of several thousand years during terminations. A simple model demonstrates that these lags can be generated by diachronous temperature changes and do not require slower circulation rates. Most importantly, diachronous benthic ?18O responses must be taken into account when comparing Atlantic and Pacific benthic ?18O records or when using benthic ?18O records as a proxy for the timing of ice volume change.

Lisiecki, Lorraine E.; Raymo, Maureen E.

2009-09-01

64

Benthic Community Assessment Rapid Bioassessment Protocol: Benthic Macroinvertebrates (EPA 1989, 1999) .........................665  

E-print Network

is presented below. However, the Rapid Bioassessment Protocols (RBP) outlined by the U.S. EPA (EPA 1989, 1999) have been proven to be efficient and effective in small streams and rivers. The EPA is currently developing guidance for benthic char acterization in lakes, large rivers, and coastal areas. States

Pitt, Robert E.

65

Benthic fluxes in San Francisco Bay  

USGS Publications Warehouse

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.

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

66

Sedimentary organic carbon budget of coastal sediments and the importance of benthic-pelagic coupling off Namhae Island in the South Sea of Korea  

NASA Astrophysics Data System (ADS)

We characterized the biogeochemical organic carbon cycles in the surface sediment layer (< 25 cm) in the coastal waters of Namhae off the South Sea of Korea. The total and diffusive sediment oxygen uptake rates were measured using an in situ benthic lander equipped with a benthic chamber and a microprofiler. The bottom water above the sediment-water interface was incubated to estimate the benthic flux of the dissolved inorganic nutrients and the total alkalinity using an in situ benthic chamber. In addition, the particulate materials vertically deposited onto the surface sediment and the sedimentation rates were quantified to calculate the sedimentary organic carbon budget. The total oxygen uptake rate was in the range 34.9 to 54.1 mmol O2 m-2d-1, which is about three times the diffusive oxygen uptake rate. An abnormal oxygen peak observed in the anoxic sediment layer suggests a higher bioirrigation activity in the sediment layer. The oxidation rate of organic carbon at the sediment surface showed a very narrow range (36 ± 7 to 37 ± 7 mmol C m-2d-1), and the burial flux into the sediment layer was in the range 3 to 13 mmol C m-2d-1, which accounted for 9% to 36% of the remineralization rate of the organic carbon. The N and P requirement fluxes for pelagic production could be supported by 29% and 42% of the benthic flux, respectively, which strongly suggests a benthic-pelagic coupling in the coastal area of the South Sea of Korea.

Lee, Jae Seong; Han, Jeong Hee; An, Sung-Uk; Na, Taehee; Kwon, Jung No; Kim, Eun-Soo

2014-12-01

67

Establishing a Benthic Cabled Observatory with ROV Based Cable Deployment  

Microsoft Academic Search

The Monterey Bay Aquarium Research Institute (MBARI) in support of the MBARI Ocean Observation System (MOOS) Science Experiment 2006 (MSE06) has established a benthic cabled observatory. The goal of MSB 06 is to study deep seafloor processes within and adjacent to the outer Monterey Bay Submarine Canyon. At the study site near Shepard Meander, a Benthic Instrument Node (BIN) and

L. E. Bird; D. Graves; G. Massion; M. Chaffey; R. Keaten

2006-01-01

68

Classification of threespine stickleback along the benthic-limnetic axis  

PubMed Central

Many species of fish display morphological divergence between individuals feeding on macroinvertebrates associated with littoral habitats (benthic morphotypes) and individuals feeding on zooplankton in the limnetic zone (limnetic morphotypes). Threespine stickleback (Gasterosteus aculeatus L.) have diverged along the benthic-limnetic axis into allopatric morphotypes in thousands of populations and into sympatric species pairs in several lakes. However, only a few well known populations have been studied because identifying additional populations as either benthic or limnetic requires detailed dietary or observational studies. Here we develop a Fisher’s linear discriminant function based on the skull morphology of known benthic and limnetic stickleback populations from the Cook Inlet Basin of Alaska and test the feasibility of using this function to identify other morphologically divergent populations. Benthic and limnetic morphotypes were separable using this technique and of 45 populations classified, three were identified as morphologically extreme (two benthic and one limnetic), nine as moderately divergent (three benthic and six limnetic) and the remaining 33 populations as morphologically intermediate. Classification scores were found to correlate with eye size, the depth profile of lakes, and the presence of invasive northern pike (Esox lucius). This type of classification function provides a means of integrating the complex morphological differences between morphotypes into a single score that reflects the position of a population along the benthic-limnetic axis and can be used to relate that position to other aspects of stickleback biology. PMID:21221422

Willacker, James J.; von Hippel, Frank A.; Wilton, Peter R.; Walton, Kelly M.

2010-01-01

69

Benthic macrofauna habitat associations in Willapa Bay, Washington, USA  

Microsoft Academic Search

Estuary-wide benthic macrofauna habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [Zostera marina], Atlantic cordgrass [Spartina alterniflora], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis]) in 1996 and 7 habitats (eelgrass, Atlantic cordgrass, mud shrimp, ghost shrimp, oyster [Crassostrea gigas], bare mud\\/sand, subtidal) in 1998. Most benthic macrofaunal species inhabited multiple habitats; however, 2

Steven P. Ferraro; Faith A. Cole

2007-01-01

70

Benthic diatoms in lakes: environmental drivers and ecological  

E-print Network

Benthic diatoms in lakes: environmental drivers and ecological assessment Steffi Gottschalk Faculty #12;Benthic diatoms in lakes: environmental drivers and ecological assessment Abstract In order are frequently used for assessing ecological status in streams and for reconstructing water quality of lakes

71

Benthic photosynthesis in submerged Wadden Sea intertidal flats  

Microsoft Academic Search

In this study we compare benthic photosynthesis during inundation in coarse sand, fine sand, and mixed sediment (sand\\/mud) intertidal flats in the German Wadden Sea. In situ determinations of oxygen-, DIC- and nutrient fluxes in stirred benthic chamber incubations were combined with measurements of sedimentary chlorophyll, incident light intensity at the sediment surface and scalar irradiance within the sediment. During

Markus Billerbeck; Hans Røy; Katja Bosselmann; Markus Huettel

2007-01-01

72

A MORE COST-EFFECTIVE EMAP BENTHIC MACROFAUNAL SAMPLING PROTOCOL  

EPA Science Inventory

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

73

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

EPA Science Inventory

Benthic Nutrient Flux in a Small Estuary in Northwestern Florida(USA).Gulf and Caribbean Research 18, 15-25, 2006. Benthic nutrient fluxes of ammonium (NH4+), nitrite/nitrate (NO2-+NO3-), phosphate (PO4-), and dissolved silica (DSi) were measured in Escambia Bay, an estuar...

74

Classification of threespine stickleback along the benthic-limnetic axis.  

PubMed

Many species of fish display morphological divergence between individuals feeding on macroinvertebrates associated with littoral habitats (benthic morphotypes) and individuals feeding on zooplankton in the limnetic zone (limnetic morphotypes). Threespine stickleback (Gasterosteus aculeatus L.) have diverged along the benthic-limnetic axis into allopatric morphotypes in thousands of populations and into sympatric species pairs in several lakes. However, only a few well known populations have been studied because identifying additional populations as either benthic or limnetic requires detailed dietary or observational studies. Here we develop a Fisher's linear discriminant function based on the skull morphology of known benthic and limnetic stickleback populations from the Cook Inlet Basin of Alaska and test the feasibility of using this function to identify other morphologically divergent populations. Benthic and limnetic morphotypes were separable using this technique and of 45 populations classified, three were identified as morphologically extreme (two benthic and one limnetic), nine as moderately divergent (three benthic and six limnetic) and the remaining 33 populations as morphologically intermediate. Classification scores were found to correlate with eye size, the depth profile of lakes, and the presence of invasive northern pike (Esox lucius). This type of classification function provides a means of integrating the complex morphological differences between morphotypes into a single score that reflects the position of a population along the benthic-limnetic axis and can be used to relate that position to other aspects of stickleback biology. PMID:21221422

Willacker, James J; von Hippel, Frank A; Wilton, Peter R; Walton, Kelly M

2010-11-01

75

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...

76

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

USGS Publications Warehouse

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.

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

2009-01-01

77

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

NASA Astrophysics Data System (ADS)

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.

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

2009-04-01

78

Benthic flux of biogenic elements on the Southeastern US continental shelf: influence of pore water advective transport and benthic microalgae  

Microsoft Academic Search

In situ, paired light and dark benthic flux chamber incubations were used to estimate the exchange of nutrients, oxygen and inorganic carbon across the sediment – water interface of the South Atlantic Bight (SAB) continental shelf. The results indicate that physically forced non-diffusive pore water transport and benthic primary production (BPP) by sea floor microalgae exert a major influence on

Richard A. Jahnke; James R. Nelson; Roberta L. Marinelli; James E. Eckman

2000-01-01

79

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

PubMed Central

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

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

2013-01-01

80

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

81

Benthic effects on the polarization of light in shallow waters.  

PubMed

Measurements of the upwelling polarized radiance in relatively shallow waters of varying depths and benthic conditions are compared to simulations, revealing the depolarizing nature of the seafloor. The simulations, executed with the software package RayXP, are solutions to the vector radiative transfer equation, which depends on the incident light field and three types of parameters: inherent optical properties, the scattering matrix, and the benthic reflectance. These were measured directly or calculated from measurements with additional assumptions. Specifically, the Lambertian model used to simulate benthic reflectances is something of a simplification of reality, but the bottoms used in this study are found to be crucial for accurate simulations of polarization. Comparisons of simulations with and without bottom contributions show that only the former corroborate measurements of the Stokes components and the degree of linear polarization (DoLP) collected by the polarimeter developed at the City College of New York. Because this polarimeter is multiangular and hyperspectral, errors can be computed point-wise over a large range of scattering angles and wavelengths. Trends also become apparent. DoLP is highly sensitive to the benthic reflectance and to the incident wavelength, peaking in the red band, but the angle of linear polarization is almost spectrally constant and independent of the bottom. These results can thus facilitate the detection of benthic materials as well as future studies of camouflage by benthic biota; to hide underwater successfully, animals must reflect light just as depolarized as that reflected by benthic materials. PMID:24513934

Gilerson, Alexander A; Stepinski, Jan; Ibrahim, Amir I; You, Yu; Sullivan, James M; Twardowski, Michael S; Dierssen, Heidi M; Russell, Brandon; Cummings, Molly E; Brady, Parrish; Ahmed, Samir A; Kattawar, George W

2013-12-20

82

Benthic Microbial Response to Varying Organic Matter Inputs: An In-Situ Labeling Study in the Deep Sea  

NASA Astrophysics Data System (ADS)

Particulate organic carbon (POC) arriving at the sea floor has been altered during vertical transport from surface waters, lateral transport along the continental slope or resuspension in the benthic boundary layer. Both availability and quality (reactivity) of POC play key roles for microbially mediated organic carbon turnover, thereby being critical for carbon cycling and transfer through the ocean. The export rate of POC is not a continuous process but strongly pulsed. To investigate the influence of POC quality on the benthic turnover rates, a series of in situ-experiments was carried out in the Benguela Upwelling Region (SW-Africa). Using a benthic chamber lander, we investigated the response of the sediment community on pulsed supplies of fresh and degraded 13C-labeled phytodetritus. Sediment community oxygen consumption (SCOC) and bacterial secondary production (BSP) did not differ significantly between the experimental treatments, showing that the artificial input did not alter the biogeochemical station characteristics. However, clear differences in benthic response were observed when following the added 13C-label. The mineralisation of the added material was 1.8 to 12.8 times higher for fresh than for altered phytodetritus. Highest recovery of label occurred at the sediment surface, with single indication for non-local transport within the uppermost 4cm of sediment. Following evidence that macro- as well as microorganisms play a major role in the early diagenesis of POC, label incorporation into macrofauna and bacterial fatty acids (PLFAs) was investigated. PLFA data suggest the presence of considerable numbers of sulphate-reducing bacteria, which displayed lower incorporation rates of added label relative to aerobic bacteria in comparable studies. The pathways for carbon cycling as well as the involvement of different benthic compartments seem to depend on the quality of POC arriving at the seafloor, thereby closely coupling its sources and transport to its diagenetic degradation via a biological link.

Aspetsberger, F.; Ferdelman, T.; Witte, U.; Zabel, M.

2004-12-01

83

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

NASA Astrophysics Data System (ADS)

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

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

2012-03-01

84

Impact of crab bioturbation on benthic flux and nitrogen dynamics of Southwest Atlantic intertidal marshes and mudflats  

Microsoft Academic Search

The effect of the SW Atlantic intertidal burrowing crab Neohelice (Chasmagnathus) granulata on benthic metabolism, benthic flux, and benthic N cycling processes was investigated through field experiments and in situ benthic chambers incubations. Our experimental results show that the presence and activity of N. granulata and its burrows may affect the direction and magnitude of nutrient benthic fluxes. Bioturbation enhanced ammonium

Eugenia Fanjul; María C. Bazterrica; Mauricio Escapa; María A. Grela; Oscar Iribarne

2011-01-01

85

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...

86

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...

87

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...

88

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...

89

Benthic macrofauna–habitat associations in Willapa Bay, Washington, USA  

Microsoft Academic Search

Estuary-wide benthic macrofauna–habitat associations in Willapa Bay, Washington, United States, were determined for 4 habitats (eelgrass [Zostera marina], Atlantic cordgrass [Spartina alterniflora], mud shrimp [Upogebia pugettensis], ghost shrimp [Neotrypaea californiensis]) in 1996 and 7 habitats (eelgrass, Atlantic cordgrass, mud shrimp, ghost shrimp, oyster [Crassostrea gigas], bare mud\\/sand, subtidal) in 1998. Most benthic macrofaunal species inhabited multiple habitats; however, 2 dominants,

Steven P. Ferraro; Faith A. Cole

2007-01-01

90

Benthic Metabolism as an Indicator of Stream Ecosystem Health  

Microsoft Academic Search

We tested direct and indirect measures of benthic metabolism as indicators of stream ecosystem health across a known agricultural\\u000a land-use disturbance gradient in southeast Queensland, Australia. Gross primary production (GPP) and respiration (R24) in benthic chambers in cobble and sediment habitats, algal biomass (as chlorophyll a) from cobbles and sediment cores, algal biomass accrual on artificial substrates and stable carbon isotope

Christine S. Fellows; Joanne E. Clapcott; James W. Udy; Stuart E. Bunn; Bronwyn D. Harch; Michael J. Smith; Peter M. Davies

2006-01-01

91

Benthic primary productivity on the Georgia midcontinental shelf: Benthic flux measurements and high-resolution, continuous in situ PAR records  

Microsoft Academic Search

Continuous, 7 year records of above-water, near-surface water column and near-bottom measurements of photosynthetically active radiation (PAR) were used in conjunction with in situ chamber measurements to estimate magnitude and seasonal variations in benthic primary productivity (BPP) on the Georgia continental shelf. Correlation between BPP and PAR flux was established with 19 light\\/dark benthic chamber and PAR flux measurements at

R. A. Jahnke; J. R. Nelson; M. E. Richards; C. Y. Robertson; A. M. F. Rao; D. B. Jahnke

2008-01-01

92

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

PubMed

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

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

2014-01-01

93

The continental shelf benthic iron flux and its isotope composition  

NASA Astrophysics Data System (ADS)

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.

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

2010-07-01

94

Benthic Biogeochemistty Beneath the Mississippi River Plume  

Microsoft Academic Search

ABSTRACT:,Biogeochemical,processes,occurring,near,the,sediment-water,interface,of,shallow,(-20 m),water,sedi- ments,lying,beneath,the,Mississippi,River,plume,on,the,Louisiana,shelf,were,studied,using,benthic,chambers,and,sedi- ment,cores.,Three,sites,were,chosen,with,distinctly,different,characteristics.,One,was,overlain,by,oxic,water,where,aerobic respiration,dominated,organic,matter,remhreralization.,The,second,site was,overlain,by oxic,water,but,organic,matter remineralization,was,dominated,by sulfate,reduction.,The third,site was,overlain,by hypoxic,water,and,aerobic,remin- eralization was of minor significance. Major differences were observed in the fluxes of CO,(17-56 mm01 m-r d-l), 0,(2- 56 mm01 m-r d-l) and nutrients (e.g., NH 4+, 2.642 mm01 m-* d-l) across the sediment-water interface, and the relative importance of different electron acceptors, even though the sites were

W. Morse; T. Rowe

95

Benthic lead fluxes in San Francisco Bay, California, USA  

SciTech Connect

Porewater concentration gradients indicate relatively large benthic fluxes of Pb from sediments in the San Francisco Bay estuary. Gradients in total dissolved (<0.45 [mu]m) Pb concentrations in sediment porewaters, which range from 0.07-19.2 nM, parallel gradients in ammonia and dissolved Fe in sediment cores from the bay. Corresponding Fickian diffusive fluxes range from 2.6 [times] 10[sup [minus]9] moles m[sup [minus]2] d[sup [minus]1] to 3.1 [times] 10[sup [minus]8] moles m[sup [minus]2] d[sup [minus]1] in anoxic surface (<2 cm) sediments along the periphery of the estuary. These indicate the net diffusive benthic flux of Pb from sediments in San Francisco Bay (3-31 moles d[sup [minus]1]) is at least an order of magnitude greater than the fluvial input of dissolved Pb to the estuary (0.2 moles d[sup [minus]1]) during low flow periods. Moreover, estimates of the total benthic Pb flux, which were based on HAMMOND et al. (1985) irrigation benthic flux model, are two- to six-fold greater (6-186 moles d[sup [minus]1]) than the estimates of diffusive fluxes. Therefore, the total benthic flux of Pb from the bay's sediments may be within the order of magnitude of the total anthropogenic flux of Pb to the San Francisco Bay estuary (965-8,410 moles d[sup [minus]1]).

Rivera-Duarte, I.; Flegal, A.R. (Univ. of California, Santa Cruz, CA (United States))

1994-08-01

96

Sequential sampling: A cost-effective approach for monitoring benthic macroinvertebrates in environmental impact assessments  

Microsoft Academic Search

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.

Vincent H. Resh; Donald G. Price

1984-01-01

97

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

EPA Science Inventory

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

98

Benthic resources are the key to Daphnia middendorffiana survival in a high arctic pond  

E-print Network

Benthic resources are the key to Daphnia middendorffiana survival in a high arctic pond MATTEO food sources for zooplankton. 2. The cladoceran Daphnia middendorffiana responded to the 13 C. Keywords: arctic pond, benthic algae, Daphnia middendorffiana, terrestrial carbon, zooplankton Introduction

Vincent, Warwick F.

99

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...

100

Distribution and faunal associations of benthic invertebrates at Lake Turkana, Kenya  

Microsoft Academic Search

The benthic environment and fauna of Lake Turkana were studied during 1978–1979 to determine distribution patterns and associations of benthic invertebrates. Lake Turkana is a large, closed-basin, alkaline lake, located in northern Kenya.

Andrew S. Cohen

1986-01-01

101

Global biodiversity patterns of benthic marine algae.  

PubMed

Species richness patterns are remarkably similar across many marine taxa, yet explanations of how such patterns are generated and maintained are conflicting. I use published occurrence data to identify previously masked latitudinal and longitudinal diversity gradients for all genera of benthic marine macroalgae and for species in the Order Bryopsidales. I also quantify the size, location, and overlap of macroalgal geographic ranges to determine how the observed richness patterns are generated. Algal genera exhibit an inverse latitudinal gradient, with biodiversity hotspots in temperate regions, while bryopsidalean species reach peak diversity in the tropics. The geographic distribution of range locations results in distinct clusters of range mid-points. In particular, widespread taxa are centered within tight latitudinal and longitudinal bands in the middle of the Indo-Pacific and Atlantic Oceans while small-ranged taxa are clustered in peripheral locations, suggesting that variation in speciation and extinction are important drivers of algal diversity patterns. Hypotheses about factors that regulate diversity contain underlying assumptions about the size and location of geographic ranges, in addition to predictions as to why species numbers will differ among regions. Yet these assumptions are rarely considered in assessing the validity of the prevailing hypotheses. I assess a suite of hypotheses, suggested to explain patterns of marine diversity, by comparing algal-richness patterns in combination with the size and location of algal geographic ranges, to the richness and range locations predicted by these hypotheses. In particular, the results implicate habitat areas and ocean currents as the most plausible drivers of observed diversity patterns. PMID:17089657

Kerswell, Ailsa P

2006-10-01

102

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

E-print Network

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

Husinec, Antun

103

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

Microsoft Academic Search

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

Steven P. Ferraro; Faith A. Cole

2011-01-01

104

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

Microsoft Academic Search

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

Steven P. Ferraro; Faith A. Cole

2011-01-01

105

Benthic Nutrient Cycling and Diagenetic Pathways in the North-western Black Sea  

Microsoft Academic Search

Benthic fluxes of nutrients and metals were measured in the coastal zone of the north-western Black Sea, which is influenced by the Danube and Dniestr rivers. The results from the benthic flux chambers deployed during two EROS 21 cruises in summer 1995 and in spring 1997 yield information on benthic nutrient cycling and diagenetic pathways at the sediment-water interface. This

J. Friedrich; C. Dinkel; G. Friedl; N. Pimenov; J. W. M. Wijsman; M.-T. Gomoiu; A. Cociasu; L. Popa; B. Wehrli

2002-01-01

106

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

E-print Network

estuarine sands affected by submarine groundwater discharge based on N2 : Ar measurements in benthic fluxwww.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

107

COMPARISON OF TWO INDICES OF BENTHIC COMMUNITY CONDITION IN CHESAPEAKE BAY  

EPA Science Inventory

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

108

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...

109

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

110

Layers and Layers  

NSDL National Science Digital Library

This lesson has students create their own rock layers by slowly adding and observing how different types of sediment interact when layered upon each other. This lesson is meant to illustrate how we can use these layers to discover the relative age of an object found in that layer by utilizing the Law of Superposition.

Cheri Tremarco

2011-10-07

111

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

NASA Astrophysics Data System (ADS)

Deep-sea benthic organisms derive food from export of organic matter produced in the photic zone, so that pelagic and benthic productivity are coupled, suggesting that severe extinction of plankton and benthos in the geological past should have been coupled. An asteroid impact at the Cretaceous/Paleogene (K/Pg) boundary (~65 Ma), however, caused mass extinction of calcifying plankton (foraminifera and nannoplankton), whereas benthic calcifyers (foraminifera) did not suffer significant extinction. Also, pelagic calcifyers did not suffer severe extinction during the carbon-cycle perturbation and global warming at the Paleocene-Eocene (P/E) boundary 10 myr later, when deep-sea benthic foraminifera did. The K/Pg extinction has been interpreted as darkness-caused collapse of productivity, but this is not supported by the lack of benthic extinction. To evaluate extinction mechanisms, we compared benthic foraminiferal and stable isotope records at ODP sites in the Pacific, SE Atlantic and Southern Oceans. Across the K/Pg boundary, the decrease in export productivity was moderate, regionally variable, and insufficient to explain the mass extinction at higher levels of the food chain. Across the P/E boundary, productivity increased in epicontinental seas and on continental margins, whereas pelagic productivity may have declined (increased trophic resource continuum). We thus found no evidence that the different benthic and pelagic extinction patterns at K/Pg and P/E were linked to changes in (export) productivity. Instead, the difference between planktic and benthic extinction patterns may have been caused by the occurrence of ocean acidification at different rates. Very rapid (faster than present anthropogenic) surface ocean acidification at the K/Pg boundary may have been due to influx of impact-generated nitric acid, followed by rapid oceanic buffering. This may have been a factor in the massive extinction of pelagic calcifyers, ammonites and top-level predators such as large fish and mosasaurs, while oceanic productivity in terms of biomass recovered rapidly. Acidification at the end of the Paleocene was triggered by the much slower injection of a large mass of carbon-compounds into the atmosphere and transfer into the oceans (~10-20 kyr), leading to severe extinction of deep-sea calcifying benthos, but much less severe turnover in the plankton. The study of the biogeography of biotic consequences of the K/Pg and P/E boundary events thus may assist in the evaluation of the varying effects on oceanic biota with varying rates and sources of acidification.

Thomas, E.; Alegret, L.

2012-12-01

112

Benthic nutrient fluxes in Cadiz Bay (SW Spain)  

Microsoft Academic Search

During summer and autumn 1988, benthic fluxes of nutrients and oxygen were measured in the Bay of Cadiz. The study was carried\\u000a out using benthic chambers and in addition by determining gradients of nutrient concentration in interstitial water. Fluxes\\u000a ranged between 13.5–24.3, 3.4–7.8, 6.1–28.4 and (? 99.4)?(? 188.5) mmol m? 2 d?1 for NH4\\u000a + , o-P, SiO2 and O2

A. Gómez-Parra; J. M. Forja

1993-01-01

113

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

NASA Astrophysics Data System (ADS)

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.

King, J. N.

2012-12-01

114

Growth form defines physiological photoprotective capacity in intertidal benthic diatoms.  

PubMed

In intertidal marine sediments, characterized by rapidly fluctuating and often extreme light conditions, primary production is frequently dominated by diatoms. We performed a comparative analysis of photophysiological traits in 15 marine benthic diatom species belonging to the four major morphological growth forms (epipelon (EPL), motile epipsammon (EPM-M) and non-motile epipsammon (EPM-NM) and tychoplankton (TYCHO)) found in these sediments. Our analyses revealed a clear relationship between growth form and photoprotective capacity, and identified fast regulatory physiological photoprotective traits (that is, non-photochemical quenching (NPQ) and the xanthophyll cycle (XC)) as key traits defining the functional light response of these diatoms. EPM-NM and motile EPL showed the highest and lowest NPQ, respectively, with EPM-M showing intermediate values. Like EPL, TYCHO had low NPQ, irrespective of whether they were grown in benthic or planktonic conditions, reflecting an adaptation to a low light environment. Our results thus provide the first experimental evidence for the existence of a trade-off between behavioural (motility) and physiological photoprotective mechanisms (NPQ and the XC) in the four major intertidal benthic diatoms growth forms using unialgal cultures. Remarkably, although motility is restricted to the raphid pennate diatom clade, raphid pennate species, which have adopted a non-motile epipsammic or a tychoplanktonic life style, display the physiological photoprotective response typical of these growth forms. This observation underscores the importance of growth form and not phylogenetic relatedness as the prime determinant shaping the physiological photoprotective capacity of benthic diatoms. PMID:25003964

Barnett, Alexandre; Méléder, Vona; Blommaert, Lander; Lepetit, Bernard; Gaudin, Pierre; Vyverman, Wim; Sabbe, Koen; Dupuy, Christine; Lavaud, Johann

2015-01-01

115

The Discovery Collections The Discovery Collections comprises both benthic and  

E-print Network

at understanding more about whale biology and their environment. As a result, many of these early samples were of these samples was funded by a levy on whale oil processing in the Falkland Islands, and was aimed pelagic, focusing on krill an important food source for whales. Even from the outset many benthic samples

Matthews, Adrian

116

Abstract--Multibeam sonar mapping techniques provide detailed benthic  

E-print Network

521 Abstract--Multibeam sonar mapping techniques provide detailed benthic habitat information. Habitat was mapped by using multibeam sonar survey techniques and categorized by using rugosity reported because of the additional amount of habitat sur- veyed in this study. The use of multibeam sonar

117

Predator-Prey Role Reversal in a Marine Benthic Ecosystem  

Microsoft Academic Search

Two closely located islands on the west coast of South Africa support widely different benthic communities. The biota at Malgas Island is dominated by seaweeds and by rock lobsters that consume settling mussels, thereby preventing the establishment of the mussels. They also prey on whelks, although one species, Burnupena papyracea, is protected from predation by a commensal bryozoan that covers

Amos Barkai; Christopher McQuaid

1988-01-01

118

Comparative Punting Kinematics and Pelvic Fin Musculature of Benthic Batoids  

E-print Network

Comparative Punting Kinematics and Pelvic Fin Musculature of Benthic Batoids Laura J. Macesic motionless, the skate's pelvic fins are planted into the substrate and then retracted caudally, which thrusts punting,'' in which only the pelvic fins were engaged. The yellow stingray, Urobatis jamaicensis

Kajiura, Stephen

119

ORIGINAL PAPER Vulnerability of benthic habitats to the aquatic invasive  

E-print Network

benthic habitat types in the SE Baltic Sea waters and the Curonian lagoon, including Klaipeda strait (ex- pressed by the maximal and minimal depths difference within a habitat), shallowness of a habitat (expressed by a minimal depth), and availability of a hard substrate. Keywords Invasibility, Invasive species

120

Assessing Benthic Impacts of Organic Enrichment from Marine Aquaculture  

Microsoft Academic Search

Benthic observations were carried out at 22 stations in the Western Isles region of the Bay of Fundy on the east coast of Canada to evaluate impacts at salmon aquaculture sites. Eleven sites were located under salmon net-pens and 11 sites (reference or control locations) were at distances > 50 m from net-pens. Total S- and redox potential (Eh) in

B. T. Hargrave; G. A. Phillips; L. I. Doucette; M. J. White; T. G. Milligan; D. J. Wildish; R. E. Cranston

1997-01-01

121

Benthic Nutrient Recycling in Port Phillip Bay, Australia  

Microsoft Academic Search

Benthic chamber measurements of the reactants and products involved with biogenic matter remineralization (oxygen, ammonium, nitrate, nitrite, phosphate, silicate, TCO2and alkalinity) were used to define solute exchange rates between the sediment and overlying water column of Port Phillip Bay, Australia. Measurements at various sites throughout the bay, conducted during the summers of 1994 and 1995, indicate that the variability in

W. M. Berelson; D. Heggie; A. Longmore; T. Kilgore; G. Nicholson; G. Skyring

1998-01-01

122

Early diagenesis and nutrient benthic fluxes in the Adriatic Sea  

Microsoft Academic Search

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

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

2003-01-01

123

Investigation of benthic phosphorus flux controls in Lake Waco, Texas  

Microsoft Academic Search

Investigations were completed to quantify the amount of phosphorus (P) available for release from the sediment of Lake Waco, Texas, as part of the Lake Waco Comprehensive Lake Management Study. Sediment oxygen demand and benthic nutrient flux measurements were obtained using an in situ chamber and an in situ nutrient analyzer available from Systea Inc. Sediment samples were also collected

Marie E. Esten; Kenneth J. Wagner

2010-01-01

124

CHARACTERISTICS OF BENTHIC ALGAL COMMUNITIES IN THE UPPER GREAT LAKES  

EPA Science Inventory

The upper Great Lakes contain a diverse array of benthic algal communities. Characteristic communities occupy substrates from the supralittoral to depths in excess of 30 m. Diatoms are the dominant taxonomic group present in terms of numbers, and usually in terms of biomass, exce...

125

DO STONEFLY PREDATORS INFLUENCE BENTHIC DISTRIBUTIONS IN STREAMS?  

Microsoft Academic Search

Experimental manipulations were conducted within the substrate of a Wisconsin stream and a Colorado stream to measure the effect of stonefly predators on the distribution of benthic invertebrates. Screen cages containing free predators, predators restricted from foraging, or no pred- ators, allowed prey migration but no predator migration over 3-d periods. The presence of Acroneuria lycorias (Perlidae) in the Wisconsin

BARBARA L. PECKARSKY; STANLEY I. DODSON

1980-01-01

126

Reservoir manipulations and benthic macroinvertebrates in a Prairie River  

Microsoft Academic Search

Samples were taken on the Tongue River, Montana, USA, during 1974 and 1975 to determine the distributions and abundances of the benthic fauna after various reservoir manipulations. The upper cold water section, influenced by hypolimnial discharge from the Tongue River Reservoir, was impoverished in insect fauna and dominated by the molluscs Physa and Sphaerium. The lower warm water sections of

James A. Gore

1977-01-01

127

Relating Remotely Sensed Optical Variability to Marine Benthic Biodiversity  

PubMed Central

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

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

2013-01-01

128

Page 1 of 30 Fundamentals of Benthic Microbial Fuel Cells  

E-print Network

in microbial ecology among BMFCs, and the potential that BMFCs have as practical - and commercially viablePage 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

Girguis, Peter R.

129

dam logic: qualitative reasoning about benthic macroinvertebrate responses  

E-print Network

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

Tullos, Desiree

130

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...

131

DETECTING BENTHIC COMMUNITY DIFFERENCES: INFLUENCE OF STATISTICAL INDEX AND SEASON  

EPA Science Inventory

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

132

risk: lessons from Triassic-Jurassic marine benthic organisms  

Microsoft Academic Search

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

Wolfgang Kiessling; Martin Aberhan

133

Calcareous nannoplankton and benthic foraminiferal assemblages from the Nazar Canyon  

E-print Network

Calcareous nannoplankton and benthic foraminiferal assemblages from the Nazaré Canyon (Portuguese, Portugal E-mail: catarina.guerreiro@hidrografico.pt Abstract. Submarine canyons are assumed to play as preferential conduits between the littoral and deep oceanic domain. Here we present first results

134

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...

135

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...

136

An Apparatus for Preparing Benthic Samples aboard Ship  

Microsoft Academic Search

We describe a safe and effective apparatus for washing and reducing the volume of benthic samples collected by grab samplers aboard ship. The sample is transferred directly from the dredge to the apparatus and then washed with water pumped through pipes in the apparatus and from onboard hoses. Wastewater and materials smaller than 0.541 mm in diameter are washed overboard.

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

2001-01-01

137

A review of benthic faunal surveys in San Francisco Bay  

USGS Publications Warehouse

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.

Nichols, Frederic H.

1973-01-01

138

Benthic nitrogen loss in the arabian sea off pakistan.  

PubMed

A pronounced deficit of nitrogen (N) in the oxygen minimum zone (OMZ) of the Arabian Sea suggests the occurrence of heavy N-loss that is commonly attributed to pelagic processes. However, the OMZ water is in direct contact with sediments on three sides of the basin. Contribution from benthic N-loss to the total N-loss in the Arabian Sea remains largely unassessed. In October 2007, we sampled the water column and surface sediments along a transect cross-cutting the Arabian Sea OMZ at the Pakistan continental margin, covering a range of station depths from 360 to 1430?m. Benthic denitrification and anammox rates were determined by using (15)N-stable isotope pairing experiments. Intact core incubations showed declining rates of total benthic N-loss with water depth from 0.55 to 0.18?mmol?N?m(-2)?day(-1). While denitrification rates measured in slurry incubations decreased from 2.73 to 1.46?mmol?N?m(-2)?day(-1) with water depth, anammox rates increased from 0.21 to 0.89?mmol?N?m(-2)?day(-1). Hence, the contribution from anammox to total benthic N-loss increased from 7% at 360?m to 40% at 1430?m. This trend is further supported by the quantification of cd(1)-containing nitrite reductase (nirS), the biomarker functional gene encoding for cytochrome cd(1)-Nir of microorganisms involved in both N-loss processes. Anammox-like nirS genes within the sediments increased in proportion to total nirS gene copies with water depth. Moreover, phylogenetic analyses of NirS revealed different communities of both denitrifying and anammox bacteria between shallow and deep stations. Together, rate measurement and nirS analyses showed that anammox, determined for the first time in the Arabian Sea sediments, is an important benthic N-loss process at the continental margin off Pakistan, especially in the sediments at deeper water depths. Extrapolation from the measured benthic N-loss to all shelf sediments within the basin suggests that benthic N-loss may be responsible for about half of the overall N-loss in the Arabian Sea. PMID:23226143

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

2012-01-01

139

Benthic Nitrogen Loss in the Arabian Sea Off Pakistan  

PubMed Central

A pronounced deficit of nitrogen (N) in the oxygen minimum zone (OMZ) of the Arabian Sea suggests the occurrence of heavy N-loss that is commonly attributed to pelagic processes. However, the OMZ water is in direct contact with sediments on three sides of the basin. Contribution from benthic N-loss to the total N-loss in the Arabian Sea remains largely unassessed. In October 2007, we sampled the water column and surface sediments along a transect cross-cutting the Arabian Sea OMZ at the Pakistan continental margin, covering a range of station depths from 360 to 1430?m. Benthic denitrification and anammox rates were determined by using 15N-stable isotope pairing experiments. Intact core incubations showed declining rates of total benthic N-loss with water depth from 0.55 to 0.18?mmol?N?m?2?day?1. While denitrification rates measured in slurry incubations decreased from 2.73 to 1.46?mmol?N?m?2?day?1 with water depth, anammox rates increased from 0.21 to 0.89?mmol?N?m?2?day?1. Hence, the contribution from anammox to total benthic N-loss increased from 7% at 360?m to 40% at 1430?m. This trend is further supported by the quantification of cd1-containing nitrite reductase (nirS), the biomarker functional gene encoding for cytochrome cd1-Nir of microorganisms involved in both N-loss processes. Anammox-like nirS genes within the sediments increased in proportion to total nirS gene copies with water depth. Moreover, phylogenetic analyses of NirS revealed different communities of both denitrifying and anammox bacteria between shallow and deep stations. Together, rate measurement and nirS analyses showed that anammox, determined for the first time in the Arabian Sea sediments, is an important benthic N-loss process at the continental margin off Pakistan, especially in the sediments at deeper water depths. Extrapolation from the measured benthic N-loss to all shelf sediments within the basin suggests that benthic N-loss may be responsible for about half of the overall N-loss in the Arabian Sea. PMID:23226143

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

2012-01-01

140

Orbital forcing of deep-sea benthic species diversity  

USGS Publications Warehouse

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

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

1997-01-01

141

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...

142

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

NASA Astrophysics Data System (ADS)

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

Tamura, Y.; Tsuchiya, M.

2011-09-01

143

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)

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.

Kelly-Slatten, K.

2013-12-01

144

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

USGS Publications Warehouse

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).

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

2012-01-01

145

Age and correlation of California Paleogene benthic foraminiferal stages  

USGS Publications Warehouse

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

Poore, Richard Z.

1980-01-01

146

Ural River benthic communities response on the chemical spill  

SciTech Connect

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

Tarasov, A.G. [Astrakhan State Technical Univ. (Russian Federation)

1995-12-31

147

Maestrichtian benthic foraminifers from Ocean Point, North Slope, Alaska ( USA).  

USGS Publications Warehouse

Previous studies of fauna and flora from Ocean Point, Alaska, have suggested ages ranging from Campanian to early Eocene and that these assemblages are either highly endemic or commonplace. I demonstrate that the moderately abundant benthic foraminifers constitute early Maestrichtian boreal assemblages common to Canada and northern Europe. Paleoenvironmental analysis indicates that deposition took place in outer neritic settings (50 to 150m). The Ocean Point benthic foraminiferal assemblages contain species that migrated from the US Gulf Coast, North American Interior and Europe during the Campanian, and from Europe during the Maestrichtian. These faunal affinities suggest that seaways connected the Arctic to the North American Interior and Atlantic during the Campanian and that a shallow seaway connected the Arctic to the Atlantic during the early Maestrichtian. - from Author

McDougall, K.

1987-01-01

148

An assessment of seabird influence on Arctic coastal benthic communities  

NASA Astrophysics Data System (ADS)

It is well recognized that seabirds, particularly those nesting in coastal colonies, can provide significant nutrient enrichment to Arctic terrestrial ecosystems. However, little is known about the fate of bird-derived nutrients that return to the marine environment and potentially concentrate below the colonies. To attempt to assess the influence of this potential nutrient enrichment of the coastal benthic community, samples of macroalgae, sea urchins (mainly algivores), and hermit crabs (scavengers) were collected at two Arctic localities (Spitsbergen), (1) below a mixed colony of guillemots and kittiwakes, and (2) in an adjacent geomorphologically similar location not influenced by the seabird colony. A much higher nitrogen stable isotope ratio (?15N) and total nitrogen content were found in terrestrial plants sampled below the colony than away from it. In benthic macroalgae, however, there were no ?15N differences. This might result from the timing of an intensive growth period in macroalgae in late winter/early spring, when there is little or no runoff from the land, and/or ornithogenic nutrients being directly incorporated by phytoplankton. Sea urchins showed higher ?15N and total N in the control site comparing to the colony-influenced area, suggesting differential food sources in their diet and a role of scavenging/carnivory on higher trophic levels there. Opportunistically feeding hermit crabs showed ?15N and total N enrichment below the seabird colony, suggesting dependence on detritus derived from food chains originating from pelagic producers. Our results indicate that seabirds in the Arctic may fertilize coastal benthic communities through pelagic-benthic coupling, while having no direct impact on bottom primary production.

Zmudczy?ska-Skarbek, Katarzyna; Balazy, Piotr; Kuklinski, Piotr

2015-04-01

149

Assessing benthic impacts of organic enrichment from marine aquaculture  

Microsoft Academic Search

Benthic observations were carried out at 22 stations in the Western Isles region of the Bay of Fundy on the east coast of\\u000a Canada to evaluate impacts at salmon aquaculture sites. Eleven sites were located under salmon net-pens and 11 sites (reference\\u000a or control locations) were at distances > 50 m from net-pens. Total S? and redox potential (Eh) in

B. T. Hargrave; G. A. Phillips; L. I. Doucette; M. J. White; T. G. Milligan; D. J. Wildish; R. E. Cranston

1997-01-01

150

Benthic nutrient fluxes in a eutrophic, polymictic lake  

Microsoft Academic Search

Sediment release rates of soluble reactive phosphorus (SRP) and ammonium (NH4) were determined seasonally at three sites (water depth 7, 14 and 20 m) in Lake Rotorua using in situ benthic chamber incubations.\\u000a Rates of release of SRP ranged from 2.2 to 85.6 mg P m?2 d?1 and were largely independent of dissolved oxygen (DO) concentration. Two phases of NH4

D. F. Burger; D. P. Hamilton; C. A. Pilditch; M. M. Gibbs

151

Benthic nutrient fluxes in a eutrophic, polymictic lake  

Microsoft Academic Search

Sediment release rates of soluble reactive phosphorus (SRP) and ammonium (NH4) were determined seasonally at three sites (water depth 7, 14 and 20 m) in Lake Rotorua using in situ benthic chamber incubations.\\u000a Rates of release of SRP ranged from 2.2 to 85.6 mg P m?2 d?1 and were largely independent of dissolved oxygen (DO) concentration. Two phases of NH4

D. F. Burger; D. P. Hamilton; C. A. Pilditch; M. M. Gibbs

2007-01-01

152

Mobile fishing gear reduces benthic megafaunal production on Georges Bank  

USGS Publications Warehouse

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

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

2003-01-01

153

Preferential dissolution of benthic foraminiferal calcite during laboratory reductive cleaning  

Microsoft Academic Search

We have investigated the effect of cleaning procedures on eight element\\/Ca ratios in three widely used benthic foraminifera species from core top and down core sediments. Two cleaning techniques were employed: (1) comparison between “Mg-cleaning” and “Cd-cleaning” methods and (2) comparison between the various constituent reagents. Li\\/Ca, B\\/Ca, and Sr\\/Ca ratios remained unchanged for samples subjected to different treatments, but

Jimin Yu; Henry Elderfield; Mervyn Greaves; Jason Day

2007-01-01

154

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

Microsoft Academic Search

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

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

2009-01-01

155

Benthic communities on a sandy Ligurian beach (NW Mediterranean)  

Microsoft Academic Search

The different components of the benthic community of a sandy microtidal beach (Arenzano) in Liguria (NW Mediterranean) were\\u000a investigated during late spring (May) 2002 and 2003. Sampling was carried out in two transects, chosen in order to represent\\u000a the characteristics of the entire beach and their eventual spatial variations. Each transect included two stations: one placed\\u000a in the swash zone

Anabella Covazzi Harriague; Luigi Gaozza; Alessandro Montella; Cristina Misic

2006-01-01

156

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

PubMed Central

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

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

2014-01-01

157

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

NASA Astrophysics Data System (ADS)

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

Kim, Tae-Hoon; Kim, Guebuem

2014-12-01

158

Global warming and mass mortalities of benthic invertebrates in the mediterranean sea.  

PubMed

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

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

2014-01-01

159

Zebra mussel effects on benthic invertebrates: physical or biotic?  

USGS Publications Warehouse

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

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

1996-01-01

160

Improved oxygen isotope temperature calibrations for cosmopolitan benthic foraminifera  

NASA Astrophysics Data System (ADS)

Despite decades of use as a paleoceanographic proxy, considerable uncertainty still surrounds the temperature dependence of benthic foraminiferal ?18O. Widely applied paleotemperature equations may mix non-equilibrium foraminifera with equilibrium synthetic calcite, resulting in temperature sensitivities that are too large. Warm-water foraminiferal calibrations may give temperature sensitivities that are too small for very cold waters. Here we combine new core top measurements from the Florida Straits and the Arctic Ocean with published data to derive new ?18O:temperature relationships for three groups of benthic foraminifera. We derive a quadratic equation for Cibicidoides and Planulina that agrees well with equilibrium synthetic calcite, and that should be applicable over all oceanographic temperatures. We find that Uvigerina is not at equilibrium and is isotopically heavier than Cibicidoides and Planulina by 0.47‰, in contrast to the historically used 0.64‰. Hoeglundina elegans is further enriched and appears to be slightly heavier than equilibrium aragonite. Finally we discuss the implications of the Florida Straits observations for the hypothesis that benthic foraminifera precipitate their shells from a pH-dependent mixture of bicarbonate and carbonate ions.

Marchitto, T. M.; Curry, W. B.; Lynch-Stieglitz, J.; Bryan, S. P.; Cobb, K. M.; Lund, D. C.

2014-04-01

161

Sediment toxicity and benthic communities in mildly contaminated mudflats  

SciTech Connect

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

Nipper, M.G.; Roper, D.S.; Williams, E.K.; Martin, M.L.; Van Dam, L.F.; Mills, G.N. [National Inst. of Water and Atmospheric Research Ltd., Hamilton (New Zealand)

1998-03-01

162

Sequential decision plans, benthic macroinvertebrates, and biological monitoring programs  

NASA Astrophysics Data System (ADS)

A common obstacle to the inclusion of benthic macroinvertebrates in water quality monitoring programs is that numerous sample units must be examined in order to distinguish between impacted and unimpacted conditions, which can add significantly to the total cost of a monitoring program. Sequential decision plans can be used to reduce this cost because the number of sample units needed to classify a site as impacted or unimpacted is reduced by an average of 50%. A plan is created using definitions of unimpacted and impacted conditions, a description of the mathematical distribution of the data, and definitions of acceptable risks of type I and II errors. The applicability of using sequential decision plans and benthic macroinvertebrates in water quality monitoring programs is illustrated with several examples (e.g., identifying moderate and extreme changes in species richness in response to acid mine drainage; assessing the impact of a crude oil contamination on the density of two benthic populations; monitoring the effect of geothermal effluents on species diversity). These examples use data conforming to the negative binomial, Poisson, and normal distributions and define impact as changes in population density, species richness, or species diversity based on empirical data or the economic feasibility of the sequential decision plan. All mathematical formulae and intermediate values are provided for the step-by-step calculation of each sequential decision plan.

Jackson, John K.; Resh, Vincent H.

1989-07-01

163

Benthic habitat characterisation of soft-bottom continental shelves: Integration of acoustic surveys, benthic samples and trawling disturbance intensity  

NASA Astrophysics Data System (ADS)

Eleven sites were located on Mediterranean continental shelves to explore the link between the physical characteristics and epibenthic fauna from soft-sediment habitats. These sites, at 32-82 m in depth, were associated with fishing grounds and the trawling intensity was estimated at the site scale to assess the effects of trawling on benthic communities. Each site was surveyed with Multi-Beam (bathymetry and backscatter), side-scan sonar, benthic grabs and a surface dredge. The sites were clustered in three habitat types. Habitat 1, with moderate trawling disturbance, was characterised by homogeneous mud and associated epifauna that was also highly homogeneous across sites. Habitat 2, with sandy mud and scattered gravel and rocks, had a high abundance of sessile suspension feeders that probably attach to the coarser substratum and benefit from the low fishing disturbance in these sites. Habitat 3 included sites with heterogeneous sediments with maërl as the prevailing biocenosis and having the highest species richness, despite being subjected to variable trawling intensity. Statistical models were used to relate environmental parameters and the species abundance. More than 3 physical variables were necessary to explain the epifaunal patterns across sites, including the percentage of mud, sediment heterogeneity and fishing effort. These analyses are an essential step for extrapolating information from benthic samples to the larger scale of habitats, mapped through acoustic surveys. Despite this, a good integration is required between the mapping of physical habitat distribution and the ecological knowledge of communities.

de Juan, S.; Lo Iacono, C.; Demestre, M.

2013-01-01

164

A Servicewide Benthic Mapping Program for National Parks  

USGS Publications Warehouse

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.

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

2010-01-01

165

Effects of deposit-feeding macrofauna on benthic bacteria, viruses, and protozoa in a silty freshwater sediment.  

PubMed

In microcosm experiments, we simultaneously tested the effects of increased numbers of deposit-feeding macrofauna (chironomids, oligochaetes and cladocerans) on the standing stock, activities and interactions of heterotrophic bacteria, viruses, and bacterivorous protozoa (heterotrophic nanoflagellates and ciliates) in the aerobic layer of a silty littoral freshwater sediment. On average, bacterial secondary production was stimulated between 11 and 29% by all macrofaunal groups compared to control experiments without macrofauna addition. Bacterial standing stock increased significantly by 8 and 13% in case of chironomids and cladocerans, respectively. Oligochaetes and chironomids produced significant negative effects on viral abundance while the results with cladocerans were inconsistent. The addition of oligochaetes and chironomids resulted in a significant decrease by on average 68 and 32% of viral decay rates, respectively, used as a measure of viral production. The calculated contribution of virus-induced lysis to benthic bacterial mortality was low, with 2.8 to 11.8% of bacterial secondary production, and decreased by 39 to 81% after the addition of macrofauna compared to the control. The abundances of heterotrophic nanoflagellates were significantly reduced by 20% by all tested macrofauna groups, while ciliates showed inconsistent results. The importance of heterotrophic nanoflagellate grazing on benthic bacteria was very low (<1% of bacterial secondary production) and was further reduced by elevated numbers of macrofauna. Thus, the selected deposit feeding macrofauna groups seem to have several direct and indirect and partly antagonistic effects on the benthic bacterial compartment through the enhancement of bacterial production and the reduction of virus-induced cell lysis and protozoan grazing. PMID:17876654

Wieltschnig, Claudia; Fischer, Ulrike R; Velimirov, Branko; Kirschner, Alexander K T

2008-07-01

166

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...

167

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

E-print Network

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

Vallino, Joseph J.

168

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...

169

Enhanced biodegradation of phthalate acid esters in marine sediments by benthic diatom Cylindrotheca closterium.  

PubMed

Cylindrotheca closterium, a marine benthic diatom, was inoculated on the surface of marine sediments spiked with diethyl phthalate (DEP) and dibutyl phthalate (DBP) to investigate the effects of benthic microalgae on the degradation of the contaminants. The elimination of DEP and DBP from unsterilized sediments with C. closterium (treatment BA) was compared with that from unsterilized sediments without C. closterium (treatment B), sterilized sediments with C. closterium (treatment A) and sterilized sediments without C. closterium (treatment N). The results showed that during the 8-day experiment, inoculation with C. closterium increased the removal rates of the contaminants from the sediments, and more significantly from the surface layer (top 0.5cm) of sediments than from the bottom layer of sediments. In the surface sediments, the first-order elimination rate constants (k) of DEP and DBP were in the order of treatment BA (2.098 and 0.309d(-1))>treatment B (0.460 and 0.256d(-1))>treatment A (0.216 and 0.039d(-1))>treatment N (nil (no data)), indicating that microbial degradation played a major role in the removal of the contaminants from the sediments. A similar trend was also observed in bottom sediments (0.444 and 0.165d(-1) in treatment BA, 0.329 and 0.194d(-1) in treatment B, 0.129d(-1) and nil in treatment A), but the difference of k values between treatments BA and B was relatively small. The positive effect of C. closterium on total phospholipid fatty acid (PLFA) content in sediments was observed, which was mainly related to the increase of biomass of aerobic bacteria as a result of improved sediment oxygenation and release of exudates (e.g. exopolysaccharides) by C. closterium. Moreover, Pearson correlation analysis showed a significant positive correlation between the elimination ratios of the contaminants and abundance of total aerobic bacterial PLFAs, suggesting that aerobic bacteria played a key role in C. closterium-promoted degradation of the contaminants in sediments. PMID:25481253

Li, Ying; Gao, Jing; Meng, Fanbo; Chi, Jie

2015-03-01

170

Distribution of benthic algae and macroinvertebrates along a thermal stream gradient  

Microsoft Academic Search

The distribution and abundance of benthic algae and macroinvertebrates were examined along a natural thermal gradient formed by hot springs in Little Geysers Creek, Sonoma Co., California, USA. Maximum water temperatures ranged from 52 °C at the uppermost station to 23 °C at a station 400 m downstream. Benthic chlorophyll a decreased exponentially from 2.5 g m?2 at 52 °C

Gary A. Lambertii; Vincent H. Resh

1985-01-01

171

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

Technology Transfer Automated Retrieval System (TEKTRAN)

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

172

Sea-level and deep water temperature changes derived from benthic foraminifera isotopic records  

Microsoft Academic Search

We show that robust regressions can be established between relative sea-level (RSL) data and benthic foraminifera oxygen isotopic ratios from the North Atlantic and Equatorial Pacific Ocean over the last climatic cycle. We then apply these regressions to long benthic isotopic records retrieved at one North Atlantic and one Equatorial Pacific site to build a composite RSL curve, as well

C. Waelbroeck; L. Labeyrie; E. Michel; J. C. Duplessy; J. F. McManus; K. Lambeck; E. Balbon; M. Labracherie

2002-01-01

173

Interspecific Comparisons and the Potential Importance of Nutrient Excretion by Benthic Fishes in a Large Reservoir  

Microsoft Academic Search

Fishes can provide an important link between benthic and pelagic habitats by removing nutrients from sediments and excreting them into the water column. The relative importance of nutrients excreted by fishes to ecosystem productivity may vary among species and with abiotic conditions. I measured excretion rates of three benthic feeding fishes, gizzard shad Dorosoma cepedianum, smallmouth buffalo Ictiobus bubalus, and

Keith B. Gido

2002-01-01

174

Benthic Foraminifera as ecological indicators for water quality on the Great Barrier Reef  

Microsoft Academic Search

Benthic foraminifera are established indicators for Water Quality (WQ) in Florida and the Caribbean. However, nearshore coral reefs of the Great Barrier Reef (GBR) and other Pacific regions are also subjected to increased nutrient and sediment loads. Here, we investigate the use of benthic foraminifera as indicators to assess status and trends of WQ on GBR reefs. We quantified several

Sven Uthicke; Kristie Nobes

2008-01-01

175

Benthic fluxes and the cycling of biogenic silica and carbon in two southern California borderland basins  

Microsoft Academic Search

Benthic fluxes in two southern California borderland basins have been estimated by modeling water column property gradients, by modeling pore water gradients and by measuring changes in concentration in a benthic chamber. Results have been used to compare the different methods, to establish budgets for biogenic silica and carbon and to estimate rate constants for models of CaCO 3 dissolution.

W. M. Berelson; D. E. Hammond; K. S. Johnson

1987-01-01

176

Benthic fluxes and the cycling of biogenic silica and carbon in two southern California borderland basins  

Microsoft Academic Search

Benthic fluxes in two southern California borderland basins have been estimated by modeling water column property gradients, by modeling pore water gradients and by measuring changes in concentration in a benthic chamber. Results have been used to compare the different methods, to establish budgets for biogenic silica and carbon, and to estimate rate constants for models of CaCOâ dissolution. In

W. M. Berelson; D. E. Hammond; K. S. Johnson

1987-01-01

177

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

Microsoft Academic Search

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

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

1997-01-01

178

Benthic fluxes and pore water studies from sediments of the central equatorial north Pacific: Nutrient diagenesis  

Microsoft Academic Search

Benthic exchange rates of radon-222, oxygen, nitrate, ammonia, and silica were determined using an in situ benthic flux chamber and by modeling pore water profiles at three sites in the central equatorial north Pacific. A comparison of these results reveals several artifacts of pore water collection and processing. Whole-core squeezer (WCS) silica profiles are influenced by adsorption during squeezing and

W. M. Berelson; D. E. Hammond; D. O'Neill; X.-M. Xu; C. Chin; J. Zukin

1990-01-01

179

Bioturbation, sediment fluxes and benthic community structure around a salmon cage farm in Loch Creran, Scotland  

Microsoft Academic Search

This study examined bioturbation along an organic carbon gradient away from an Atlantic salmon farm and sought to determine relationships between benthic fluxes, mixing intensity and the infaunal community structure. Macrofaunal community structure, abundance and biomass were examined at stations with varying quantities and qualities of organic matter input. In situ benthic chambers were used to determine oxygen and nutrient

Lois A Nickell; Kenneth D Black; David J Hughes; Julian Overnell; Tim Brand; Thomas D Nickell; Eric Breuer; S Martyn Harvey

2003-01-01

180

Benthic Respiration and Inorganic Nutrient Fluxes in the Estuarine Region of Patos Lagoon (Brazil)  

Microsoft Academic Search

In situ benthic flux chamber experiments were performed during late austral spring and early summer of 1996 at eleven nearshore locations in the southern Patos Lagoon, Brazil. The Patos Lagoon is the largest lagoonal system in South America and is a very important nursery ground for local fin fish and shell fish fisheries. These are the first benthic flux measurements

L. F. NIENCHESKI; R. A. JAHNKE

2002-01-01

181

Continental Shelf Research 23 (2003) 457481 A time series of benthic flux measurements from  

E-print Network

Continental Shelf Research 23 (2003) 457­481 A time series of benthic flux measurements from September 2002; accepted 3 December 2002 Abstract In situ incubation chamber measurements of benthic. Variability in nutrient (Si, PO4 2+ , NH3, NO3 � ) and trace metal (Mn, Fe (II), Cu) fluxes correlate

Burdige, David

182

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...

183

Spectrometric constraint in analysis of benthic diatom biomass using monospecific cultures  

Microsoft Academic Search

Among microphytobenthic species (unicellular algae and cyanobacteria), benthic diatoms are often the most common photosynthetic organisms colonizing shallow marine environment such as an intertidal flat. As such areas, particularly mudflats of limited access for point sampling, remote sensing techniques have the potential to map diatom biomass. This study used two monospecific cultures of the benthic diatoms Navicula ramosissima and Entomoneis

V. Méléder; L. Barillé; P. Launeau; V. Carrère; Y. Rincé

2003-01-01

184

Resolving the cause of large differences between deglacial benthic foraminifera radiocarbon measurements in Santa Barbara Basin  

NASA Astrophysics Data System (ADS)

To better understand the deglacial upwelling pattern in the east Pacific, we have made radiocarbon (14C) measurements on benthic foraminifera and macrofauna from a 3.5 m long interval in ODP Core 893A from Santa Barbara Basin, California, representing early deglaciation. This work serves to investigate the source of apparent disagreement between radiocarbon data sets from Leibnitz Laboratory, Kiel University (Kiel) and Carbon Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory (LLNL). These data sets are based on measurements of mixed benthic and mixed planktonic foraminifera. Interlaboratory 14C results are similar for the planktonic foraminiferal analyses; however, Kiel measurements on mixed benthic foraminifera are much older than mixed benthic measurements from equivalent depths measured at LLNL. Our new results show distinct 14C differences between taxa, with Pyrgo sp. giving ages consistently older than Kiel measurements on mixed benthic taxa, while ages for Nonionellina sp., Buliminella sp., Uvigerina sp., and benthic macrofauna were much younger, even younger than the LLNL mixed benthic data. The new data supports benthic-planktonic age offsets of no more than 300 years, indicating that bottom waters within the basin remained significantly younger during early deglaciation than some previous results have suggested and are thus consistent with sedimentary and faunal evidence for well-oxygenated conditions.

Magana, Alexandra L.; Southon, John R.; Kennett, James P.; Roark, E. Brendan; Sarnthein, Michael; Stott, Lowell D.

2010-12-01

185

Resolving the cause of large differences between deglacial benthic foraminifera radiocarbon measurements in Santa Barbara Basin  

NASA Astrophysics Data System (ADS)

To better understand the deglacial upwelling pattern in the East Pacific, we have made radiocarbon (14C) measurements on benthic foraminifera and macrofauna from a 3.5 meter long interval in ODP Core 893A from Santa Barbara Basin, California representing early deglaciation. This work serves to investigate the source of apparent disagreement between radiocarbon datasets from Leibnitz Laboratory, Kiel University (Kiel) and Carbon Center for Accelerator Mass Spectrometry, Lawrence Livermore National Laboratory (LLNL). These datasets are based on measurements of mixed benthic and mixed planktonic foraminifera. Inter-laboratory 14C results are similar for the planktonic foraminiferal analyses, however Kiel measurements on mixed benthic foraminifera are much older than mixed benthic measurements from equivalent depths measured at LLNL. Our new results show distinct 14C differences between taxa, with Pyrgo sp. giving ages consistently older than Kiel measurements on mixed benthic taxa; while ages for Nonionellina sp., Buliminella sp., Uvigerina sp. and benthic macrofauna were much younger- even younger than the LLNL mixed benthic data. The new data supports benthic-planktonic age offsets of no more than 300 years, indicating that bottom waters within the basin remained significantly younger during early deglaciation than some previous results have suggested and thus consistent with sedimentary and faunal evidence for well oxygenated conditions.

Magana, A. L.; Southon, J. R.; Kennett, J.; Roark, E.; Sarnthein, M.; Stott, L. D.

2010-12-01

186

DEVELOPMENT OF AN INDEX OF BENTHIC CONDITION FOR COASTAL AREAS OF THE GULF OF MAINE  

EPA Science Inventory

The National Coastal Assessment has sampled benthic assemblages each summer since 2000 in coastal areas of the U.S. Gulf of Maine. We are developing a multimetric index to be used as an indicator of benthic condition for both spatial comparisons of condition along the coast and f...

187

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

EPA Science Inventory

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

188

Effects of Bridge Shading on Estuarine Marsh Benthic Invertebrate Community Structure and  

E-print Network

Effects of Bridge Shading on Estuarine Marsh Benthic Invertebrate Community Structure and Function Bloomington, Indiana 47405, USA STEPHEN W. BROOME MICHAEL D. SANCLEMENTS Department of Soil Science North of bridge shading on estuarine marsh food webs was assessed by comparing benthic invertebrate communities

Craft, Christopher B.

189

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

EPA Science Inventory

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

190

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...

191

Distribution of trace elements in the tissues of benthic and pelagic fish from the Kerguelen Islands  

E-print Network

1 Distribution of trace elements in the tissues of benthic and pelagic fish from the Kerguelen concentrations differences might be related to diet and feeding habits of benthic and pelagic fish species-enrichment in the polar food webs typically explained by essential elements depletion. In fact, Zn concentrations in fish

Boyer, Edmond

192

14C as a tracer of labile organic matter in Antarctic benthic food webs  

Microsoft Academic Search

14C measurements were made on surface plankton, particle-trap material, surface sediment, benthic invertebrate gut contents, and body tissue samples to assess the effectiveness of this radioisotope as a tracer of labile organic carbon in Antarctic benthic food webs. Samples were collected on five cruises to the West Antarctic Peninsula (WAP) shelf between November 1999 and March 2001 as part of

Brett L. Purinton; David J. DeMaster; Carrie J. Thomas; Craig R. Smith

2008-01-01

193

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

E-print Network

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

194

ALIENS IN PARADISE: A COMPARATIVE ASSESSMENT OF INTRODUCED AND NATIVE MANGROVE BENTHIC COMMUNITY COMPOSITION,  

E-print Network

ttlf 75 ALIENS IN PARADISE: A COMPARATIVE ASSESSMENT OF INTRODUCED AND NATIVE MANGROVE BENTHIC project would not have been accomplished without the mangrove-loving volunteers who assisted me: Duyen Ngo Mangrove benthic community ecology and food-web structures in introduced and native mangroves were examined

Luther, Douglas S.

195

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...

196

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...

197

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

E-print Network

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

Jackson, Don

198

The benthic biological submodel in the European regional seas ecosystem model  

Microsoft Academic Search

The submodel describing benthic biology including a bioturbation module as incorporated in the European Regional Seas Ecosystem Model (ERSEM) is discussed. It is linked to a nutrient dynamic model. The structure of the benthic model food web is presented. There are four macrobenthic functional groups, meiobenthos and aerobic and anaerobic bacteria. The modelling uses ‘standard organisms’ as basic building blocks.

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

1995-01-01

199

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

EPA Science Inventory

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

200

Cumulative impacts of seabed trawl disturbance on benthic biomass, production, and species richness in different habitats  

Microsoft Academic Search

Bottom trawling causes widespread disturbance of sediments in shelf seas and can have a negative impact on benthic fauna. We conducted a large-scale assessment of bottom trawl fishing of benthic fauna in different habitats, using a theoretical, size-based model that included habitat features. Species richness was estimated based on a generalized body mass versus species richness relationship. The model was

J. G. Hiddink; S. Jennings; M. J. Kaiser; A. M. Queiros; D. E. Duplisea; G. J. Piet

2006-01-01

201

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

E-print Network

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

Rasmussen, Joseph

202

Diversity as a measure of benthic macroinvertebrate community response to water pollution  

Microsoft Academic Search

The assumption that water pollution causes a depression in the diversity of benthic macroinvertebrates as measured by the Shannon index and similar diversity indices is questioned. An interpretation of the community response of benthic macroinvertebrates to pollution in the Millers River, Massachusetts is developed from species presence-absence and abundance data in conjunction with published information on the species' environmental tolerances

Paul J. Godfrey

1978-01-01

203

Benthic macroinvertebrate richness along Sausal Creek, Oakland, California  

NASA Astrophysics Data System (ADS)

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

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

2012-12-01

204

Deep-Sea Benthic Footprint of the Deepwater Horizon Blowout  

PubMed Central

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 km2. 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 km2. 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

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

205

Benthic buffers and boosters of ocean acidification on coral reefs  

NASA Astrophysics Data System (ADS)

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

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

2013-02-01

206

Benthic buffers and boosters of ocean acidification on coral reefs  

NASA Astrophysics Data System (ADS)

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

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

2013-07-01

207

Disturbance, colonization and development of Antarctic benthic communities  

PubMed Central

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

Barnes, David K.A; Conlan, Kathleen E

2006-01-01

208

Northern Florida reef tract benthic metabolism scaled by remote sensing  

USGS Publications Warehouse

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

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

2006-01-01

209

Antarctic Porifera database from the Spanish benthic expeditions  

PubMed Central

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

Rios, Pilar; Cristobo, Javier

2014-01-01

210

Deep-sea benthic footprint of the deepwater horizon blowout.  

PubMed

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

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

211

Hydrologic controls on basin-scale distribution of benthic macroinvertebrates  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

212

Benthic Marine Algal Herbarium of L.I. Sound  

NSDL National Science Digital Library

The University of Connecticut has a tremendous collection of algae from the Long Island Sound, and back in 2001 they went ahead and photographed the original herbarium sheets featuring the preserved algae specimens. The archive is quite comprehensive, as it features all of the benthic marine macroalgal species in the Long Island Sound. All told, there are over 299 images here, and visitors are encouraged to peruse the collection by phylum, family, or name. The site also contains a list of definitions, a regional map, and information about the team that worked to make this collection a possibility.

2010-07-02

213

Domoic acid contamination within eight representative species from the benthic food web of Monterey Bay, California, USA  

Microsoft Academic Search

Benthic food webs often derive a significant fraction of their nutrient inputs from phyto- plankton in the overlying waters. If the phytoplankton include harmful algal species like Pseudo- nitzschia australis, a diatom capable of producing the neurotoxin domoic acid (DA), the benthic food web can become a depository for phycotoxins. We tested the general hypothesis that DA contami- nates benthic

Rikk G. Kvitek; Judah D. Goldberg; G. Jason Smith; Gregory J. Doucette; Mary W. Silver

2008-01-01

214

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

E-print Network

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

Levin, Lisa

215

Benthic nutrient fluxes on a basin-wide scale in the Skagerrak (North-Eastern North Sea)  

Microsoft Academic Search

Benthic ammonium, nitrite, nitrate, phosphate and silicate fluxes were measured on a basin-wide scale (14 locations) in the open Skagerrak. Fluxes were measured in situ at two of the locations using a benthic chamber lander. The benthic flux measurements revealed patterns of geographic variation of nutrient fluxed in the Skagerrak. Nitrate fluxes generally reflected sediment deposition patterns and were mainly

Per O. J. Hall; Stefan Hulth; Gustaf Hulthe; Angela Landén; Anders Tengberg

1996-01-01

216

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

E-print Network

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

deYoung, Brad

217

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

NASA Astrophysics Data System (ADS)

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

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

2014-01-01

218

Multivariate benthic ecosystem functioning in the Arctic - benthic fluxes explained by environmental parameters in the southeastern Beaufort Sea  

NASA Astrophysics Data System (ADS)

The effects of climate change on Arctic marine ecosystems and their biogeochemical cycles are difficult to predict given the complex physical, biological and chemical interactions among the ecosystem components. We studied benthic biogeochemical fluxes in the Arctic and the influence of short-term (seasonal to annual), long-term (annual to decadal) and other environmental variability on their spatial distribution to provide a baseline for estimates of the impact of future changes. In summer 2009, we measured fluxes of dissolved oxygen, nitrate, nitrite, ammonia, soluble reactive phosphate and silicic acid at the sediment-water interface at eight sites in the southeastern Beaufort Sea at water depths from 45 to 580 m. The spatial pattern of the measured benthic boundary fluxes was heterogeneous. Multivariate analysis of flux data showed that no single or reduced combination of fluxes could explain the majority of spatial variation, indicating that oxygen flux is not representative of other nutrient sink-source dynamics. We tested the influence of eight environmental parameters on single benthic fluxes. Short-term environmental parameters (sinking flux of particulate organic carbon above the bottom, sediment surface Chl a) were most important for explaining oxygen, ammonium and nitrate fluxes. Long-term parameters (porosity, surface manganese and iron concentration, bottom water oxygen concentrations) together with ?13Corg signature explained most of the spatial variation in phosphate, nitrate and nitrite fluxes. Variation in pigments at the sediment surface was most important to explain variation in fluxes of silicic acid. In a model including all fluxes synchronously, the overall spatial distribution could be best explained (57%) by the combination of sediment Chl a, phaeopigments, ?13Corg, surficial manganese and bottom water oxygen concentration. We conclude that it is necessary to consider long-term environmental variability along with rapidly ongoing environmental changes to predict the flux of oxygen and nutrients across Arctic sediments even at short timescales. Our results contribute to improve ecological models predicting the impact of climate change on the functioning of marine ecosystems.

Link, H.; Chaillou, G.; Forest, A.; Piepenburg, D.; Archambault, P.

2013-09-01

219

Measuring coral reef community metabolism using new benthic chamber technology  

USGS Publications Warehouse

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

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

2003-01-01

220

Changes in habitat heterogeneity alter marine sessile benthic communities.  

PubMed

Habitat heterogeneity is considered an important mechanism influencing diversity patterns in spatially structured habitats. However, spatial heterogeneity is not static and it can change along temporal scales. These changes, whether gradual or rapid, have the potential of forcing species extinctions or facilitating the introduction of nonnative species. Here, we present modeling results that show how changes in spatial heterogeneity over several generations can produce strong changes in benthic species composition residing in eastern Long Island Sound, USA. For many benthic species, hard substrate is a limiting resource which can vary in availability among different coastal areas. We modeled gradual changes from a heterogeneous landscape (mimicking patches of natural hard and soft substrate) to a homogenous one (analogous to a fully developed coast with hard, manmade substrate) and followed the abundance and distribution patterns of species possessing four different life histories. We also modeled changes from homogeneous to heterogeneous landscapes. We found that as regions become more homogeneous, species extinctions become more frequent and poor dispersers dominate locally. In contrast, as habitats become more heterogeneous, species distributing across localities leads to regional species coexistence and fewer extinctions. These results suggest that focusing on changing habitat heterogeneity can be a useful management strategy to prevent poor dispersing species, such as invasive ascidians, from driving communities to monocultures. PMID:21639055

Munguia, Pablo; Osman, Richard W; Hamilton, John; Whitlatch, Robert; Zajac, Roman

2011-04-01

221

Hydrologic controls on basin-scale distribution of benthic invertebrates  

NASA Astrophysics Data System (ADS)

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.

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

2014-04-01

222

Spatially-explicit hydrologic controls on benthic invertebrate habitat suitability  

NASA Astrophysics Data System (ADS)

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.

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

2014-05-01

223

Predicting the Presence of Large Fish through Benthic Geomorphic Features  

NASA Astrophysics Data System (ADS)

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

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

2013-12-01

224

Development and evaluation of sediment quality guidelines based on benthic macrofauna responses.  

PubMed

Toxicity-based sediment quality guidelines (SQGs) are often used to assess the potential of sediment contamination to adversely affect benthic macrofauna, yet the correspondence of these guidelines to benthic community condition is poorly documented. This study compares the performance of 5 toxicity-based SQG approaches to a new benthos-based SQG approach relative to changes in benthic community condition. Four of the toxicity-based SQG approaches--effects range median, logistic regression modeling (LRM), sediment quality guideline quotient 1 (SQGQ1), and consensus--were derived in previous national studies in the United States, and one was developed as a regional variation of LRM calibrated to California data. The new benthos-based SQG approach, chemical score index, was derived from Southern California benthic community data. The chemical-specific guidelines for each approach were applied to matched chemical concentration, amphipod mortality, and benthic macrofauna abundance data for Southern California. Respective results for each SQG approach were then combined into a summary metric describing the overall contamination magnitude (e.g., mean quotient) and assessed in accordance with a set of thresholds in order to classify stations into 4 categories of expected biological effect. Results for each SQG approach were significantly correlated with changes in sediment toxicity and benthic community condition. Cumulative frequency plots and effect category thresholds for toxicity and benthic community condition were similar, indicating that both types of effect measures had similar sensitivity and specificity of response to contamination level. In terms of discriminating among multiple levels of benthic community condition, the toxicity-based SQG indices illustrated moderate capabilities, similar to those for multiple levels of toxicity. The National LRM, California LRM, and the chemical score index had the highest overall agreement with benthic categories. However, only the benthos-based chemical score index was consistently among the highest performing SQG indices for all measures of association (correlation, percent agreement, and weighted kappa) for both toxicity and benthos. PMID:22275113

Ritter, Kerry J; Bay, Steven M; Smith, Robert W; Vidal-Dorsch, Doris E; Field, L Jay

2012-10-01

225

Benthic nitrogen cycling traversing the capitalize peruvian oxygen minimum zone  

NASA Astrophysics Data System (ADS)

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

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

2011-10-01

226

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

SciTech Connect

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.

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

1980-01-01

227

Probabilistic sequence alignment of Late Pleistocene benthic ?18O data  

NASA Astrophysics Data System (ADS)

The stratigraphic alignment of ocean sediment cores plays a vital role in paleoceanographic research because it is used to develop mutually consistent age models for climate proxies measured in these cores. The most common proxy used for alignment is the The stratigraphic alignment of ocean sediment cores plays a vital role in paleoceanographic research because it is used to develop mutually consistent age models for climate proxies measured in these cores. The most common proxy used for alignment is the ?18O of calcite from benthic or planktonic foraminifera because a large fraction of ?18O variance derives from the global signal of ice volume. To date, alignment has been performed either by manual, qualitative comparison or by deterministic algorithms (Martinson, Pisias et al. Quat. Res. 27 1987; Lisiecki and Lisiecki Paleoceanography 17, 2002; Huybers and Wunsch, Paleoceanography 19, 2004). Here we present a probabilistic sequence alignment algorithm which provides 95% confidence bands for the alignment of pairs of benthic ?18O records. The probabilistic algorithm presented here is based on a hidden Markov model (HMM) (Levinson, Rabiner et al. Bell Systems Technical Journal, 62,1983) similar to those that have been used extensively to align DNA and protein sequences (Durbin, Eddy et al. Biological Sequence Analysis, Ch. 4, 1998). However, here the need to the alignment of sequences stems from expansion and/or contraction in the records due to changes in sedimentation rates rather than the insertion or deletion of residues. Transition probabilities that are used in this HMM to model changes in sedimentation rates are based on radiocarbon estimates of sedimentation rates. The probabilistic algorithm considers all possible alignments with these predefined sedimentation rates. Exact calculations are completed using dynamic programming recursions. The algorithm yields the probability distributions of the age at each point in the record, which are probabilistically inferred from the LR04 stack. The complication of the central (1-?)% intervals of these distributions yields the confidence bands. In an extension of this work we are rebuilding the stack using a profile HMM model (Durbin, Eddy et al, Ch. 5). We analyze the confidence bands produced for the alignments of 35 Late Pleistocene benthic ?18O records to the LR04 benthic ?18O stack. We find that the mean width of 95% confidence bands for core alignments varies between 3-23 kyr depending on the resolution and noisiness of the core's ?18O signal. Confidence bands within individual cores also vary greatly, ranging from ~0 to >40 kyr. These alignment confidence bands will allow researchers to examine the robustness of their conclusions with respect to alignment uncertainty at all points in the record. Additionally, they should aid in the identification of possible errors in inferred ages in the input record (e.g., due to core disturbances) because such errors are likely to be associated with large, local uncertainty.

Lawrence, C.; Lin, L.; Lisiecki, L. E.; Stern, J.

2013-12-01

228

Geologic characteristics of benthic habitats in Glacier Bay, southeast Alaska  

USGS Publications Warehouse

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.

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

2006-01-01

229

The Physics of Broadcast Spawning in Benthic Invertebrates  

NASA Astrophysics Data System (ADS)

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

Crimaldi, John P.; Zimmer, Richard K.

2014-01-01

230

Effects of triclosan on marine benthic and epibenthic organisms.  

PubMed

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

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

2012-08-01

231

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

USGS Publications Warehouse

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

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

2009-01-01

232

Anthropogenic and natural disturbances to marine benthic communities in Antarctica  

SciTech Connect

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.

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

1995-05-01

233

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

PubMed

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

Lalonde, Stefan V; Konhauser, Kurt O

2015-01-27

234

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. ...

235

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...

236

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

PubMed Central

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

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

1994-01-01

237

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...

238

A simple evaluation of cleaning procedures on fossil benthic foraminiferal Mg/Ca  

NASA Astrophysics Data System (ADS)

Recent studies suggest that benthic foraminiferal Mg/Ca may be useful in reconstructing deep water temperature changes during the Quaternary and on longer timescales [, 1997; , 2000; , 2002]. Because changes in deep water temperature may be small, sample preparation could play an important role in reconstructing accurate temperatures from shell Mg/Ca. A simple examination of changes in measured shell chemistry of benthic foraminifera from two intervals subjected to increasingly rigorous cleaning reveals that fossil benthic foraminiferal samples cleaned by oxidation yield lower Mg/Ca values than samples only rinsed and weak acid leached. Reductive cleaning further lowered the shell Mg/Ca of one of the two benthic species examined. Lower Mg/Ca values following oxidation and reduction appear to reflect removal of contaminant Mg associated with remnant organic matter and adsorbed phases.

Martin, Pamela A.; Lea, David W.

2002-10-01

239

DEVELOPMENT OF STANDARDIZED LARGE RIVER BIOASSESSMENT PROTOCOLS (LR-BP) FOR BENTHIC MACROINVERTEBRATE ASSEMBLAGES  

EPA Science Inventory

We conducted research comparing several methods currently in use for the bioassessment and monitoring of fish and benthic macroinvertebrate assemblages of large rivers. Fish data demonstrate that electrofishing 1000 m of shoreline is sufficient for bioassessments on boatable riv...

240

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

PubMed

Benthic status of 28 near-shore, artisanal, coral reef fishing grounds in the central Philippines was assessed (2000-2002) together with surveys of the seahorse, Hippocampus comes. Our measures of benthic quality and seahorse densities reveal some of the most degraded coral reefs in the world. Abiotic structure dominated the fishing grounds: 69% of the benthos comprised rubble (32%), sand/silt (28%) and dead coral (9%). Predominant biotic structure included live coral (12%) and Sargassum (11%). Rubble cover increased with increasing distance from municipal enforcement centers and coincided with substantial blast fishing in this region of the Philippines. Over 2 years, we measured a significant decrease in benthic 'heterogeneity' and a 16% increase in rubble cover. Poor benthic quality was concomitant with extremely low seahorse densities (524 fish per km(2)). Spatial management, such as marine reserves, may help to minimize habitat damage and to rebuild depleted populations of seahorses and other reef fauna. PMID:17645896

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

2007-09-01

241

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 ...

242

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

PubMed

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

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

2006-01-01

243

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...

244

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...

245

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

E-print Network

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...

Wang, Yuning

2006-04-12

246

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

247

Coupling between sediment dynamics and benthic communities in the coastal zone  

NASA Astrophysics Data System (ADS)

The influence of benthic communities on the sediment dynamics of the coastal zone is usually ignored in sediment transport studies, although recent studies suggest that their role could be significant. In order to investigate this topic a field experiment was carried out across the shoreface off the Ebro delta. Time series of waves, currents, water turbidity, bottom sediment characteristics and benthic communities composition were simultaneously monitored during 1 year. Two benthic communities dominated by "Bolinus brandaris" (mud sediment) and "Ophiura texturata" (fine-sand sediment) were analyzed. The major biological impacts on the sediment are related with changes in the bottom roughness and reworking of the superficial few centimeters of the sediment. The significance of these impacts largely depends on the composition and abundance of each group in the benthic community and it changes along the year.

Guillén, J.; Soriano, S.; Demestre, M.; Falqués, A.; Martín, D.; Palanques, A.; Puig, P.; Sánchez, P.; Serra, J.

2003-04-01

248

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...

249

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...

250

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...

251

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,...

252

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...

253

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

EPA Science Inventory

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

254

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...

255

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 ...

256

Habitat complexity as a determinate of benthic macroinvertebrate community structure in cypress tree reservoirs  

Microsoft Academic Search

We analyzed benthic samples (n = 128) collected from four cypress-tree population areas within a large, shallow Arkansas reservoir over a 2-year period\\u000a to investigate macroinvertebrate community distribution patterns and their relation to physical and chemical parameters. The\\u000a calculated biomass, abundance and diversity of the benthic macroinvertebrate community varied significantly both temporally\\u000a and spatially. Variations of these variables are most likely explained

Joseph M. Shostell; Bradley S. Williams

2007-01-01

257

Responses of benthic macroinvertebrate communities to natural geothermal discharges in Yellowstone National Park, USA  

Microsoft Academic Search

We examined responses of benthic macroinvertebrate communities to natural geothermal discharges in 32 streams in Yellowstone\\u000a National Park (YNP), USA. Geothermal discharges played a major role in structuring benthic communities in YNP, as downstream\\u000a communities were characterized by low species richness, reduced abundance of EPT taxa and increased abundance of tolerant\\u000a caddisflies (Trichoptera), chironomids and non-insects. While some taxa were

William H. ClementsJeffrey; Jeffrey L. Arnold; Todd M. Koel; Rob Daley; Cathie Jean

2011-01-01

258

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

Microsoft Academic Search

A study of chemical and sedimentological parameters integrated with benthic foraminifera investigation was conducted along\\u000a the northern coast of Gabes Gulf. Thirty-two samples were studied and a total of 68 benthic foraminiferal species were identified.\\u000a Heavy metals enrichment factors and total hydrocarbon concentrations showed both metal and petrogenic pollution related mainly\\u000a to phosphogypsum, sewage, and fishing activities. Statistical analysis (bivariate

Fatma Aloulou; Boubaker EllEuch; Monem Kallel

259

Responses of Estuarine Benthic Invertebrates to Sediment Burial: The Importance of Mobility and Adaptation  

Microsoft Academic Search

Estuarine benthic organisms are frequently subjected to disturbance events caused by hydrodynamic processes that disrupt and\\u000a move the sediment in which the animals reside, however the mechanisms by which physical disturbance processes affect infaunal\\u000a and epifaunal populations and communities remain poorly resolved. The responses of three infaunal and two epifaunal estuarine\\u000a benthic species to sediment disturbance (burial) were compared in

Elizabeth K. Hinchey; Linda C. Schaffner; Cara C. Hoar; Bruce W. Vogt; Lauren P. Batte

2006-01-01

260

Benthic manganese fluxes along the Oregon-California continental shelf and slope  

NASA Astrophysics Data System (ADS)

Here we examine the factors that influence the manganese (Mn) benthic flux from eastern North Pacific marine sediments, with a primary emphasis on continental shelf locations off Oregon and California and studies that involve the use of in situ benthic chambers. Typical shelf-to-shallow margin (<˜350 m) sites have benthic Mn efflux rates that average ˜8±5 ?mol m-2 d-1. In contrast, for the Eel River continental shelf region the benthic Mn efflux can be an order of magnitude higher than other shelf settings with benthic effluxes exceeding ˜50 ?mol m-2 d-1. Based on prior work and some new results, continental margin and slope sites (350-˜4000 m) have benthic Mn efflux rates that average ˜1±1 ?mol m-2 d-1. The combination of the benthic flux and Mn solid-phase data, indicate that for the continental shelf off the Umpqua and Eel Rivers, approximately 15±10% of the total Mn that is delivered to the seafloor is remobilized. The compiled data set shows that the benthic Mn efflux co-varies with the organic carbon oxidation rate with a Mn to organic carbon oxidation (Cox) ratio of ˜0.8 mmol Mn mol-1. Although this ratio can be as high as ˜5 for some Eel River sites, the generally close correspondence between Mn and organic carbon implies that the organic carbon oxidation rate exerts some primary control over the rate of the Mn efflux. The amount of organic carbon oxidized by Mn-oxides, however, represents a small fraction (i.e., generally <1%) of the total organic carbon oxidized in these seafloor sediments.

McManus, James; Berelson, William M.; Severmann, Silke; Johnson, Kenneth S.; Hammond, Douglas E.; Roy, Moutusi; Coale, Kenneth H.

2012-07-01

261

Impact of exploratory offshore drilling on benthic communities in the Minerva gas field, Port Campbell, Australia  

Microsoft Academic Search

Changes to benthic infauna caused by exploratory gas drilling operations in the Minerva field were examined experimentally using a BACI (before, after, control, impact) design. Analysis of 72×0.1 m2 Smith–McIntyre grab samples obtained from one pre-drilling and three post-drilling periods yielded a diverse fauna consisting of 196 invertebrate species and 5035 individuals. Changes to benthic community structure were assessed using

D. R. Currie; Leanne R. Isaacs

2005-01-01

262

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

NASA Astrophysics Data System (ADS)

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.

Stief, P.

2013-07-01

263

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

NASA Astrophysics Data System (ADS)

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.

Stief, P.

2013-12-01

264

Impacts of Marine Aggregate Dredging on Benthic Macrofauna off the South Coast of the United Kingdom  

Microsoft Academic Search

NEWELL, R.C.; SEIDERER, L.J.; SIMPSON, N.M., and ROBINSON, J.E., 2004. Impacts of marine aggregate dredg- ing on benthic macrofauna off the south coast of the United Kingdom. Journal of Coastal Research, 20(1), 115-125. West Palm Beach (Florida), ISSN 0749-0208. A survey of benthic macrofauna in the vicinity of a coastal marine aggregate dredging site off the south coast of UK

R. C. Newell; L. J. Seiderer; N. M. Simpson; J. E. Robinson

2004-01-01

265

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

Microsoft Academic Search

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

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

1997-01-01

266

Benthic Fluxes of Dissolved Inorganic Carbon, Nutrients and Oxygen in the Gulf of Trieste (Northern Adriatic)  

Microsoft Academic Search

Benthic fluxes of dissolved inorganic N, Si and P nutrients, alkalinity, dissolved inorganic C (DIC), and O2 from sediments in the Gulf of Trieste (northern Adriatic, Italy) were measured monthly in the period September 1995 - August 1996 using in situ incubated light benthic chambers. The highest efluxes of DIC, NH4+, PO43-, Si(OH)4, and NO3- influxes encountered in late summer

A. Bertuzzi; J. Faganeli; C. Welker; A. Brambati

1997-01-01

267

Benthic fluxes of dissolved inorganic carbon, nutrients and oxygen in the Gulf of Trieste (Northern Adriatic)  

Microsoft Academic Search

Benthic fluxes of dissolved inorganic N, Si and P nutrients, alkalinity, dissolved inorganic C (DIC), and O2 from sediments in the Gulf of Trieste (northern Adriatic, Italy) were measured monthly in the period September 1995 – August\\u000a 1996 using in situ incubated light benthic chambers. The highest efluxes of DIC, NH4\\u000a +, PO4\\u000a 3?, Si(OH)4, and NO3\\u000a ? influxes encountered

A. Bertuzzi; J. Faganeli; C. Welker; A. Brambati

1997-01-01

268

Diagenetic stoichiometry and benthic nutrient fluxes at the sediment–water interface of Lake Illawarra, Australia  

Microsoft Academic Search

Benthic flux measurements of O2, TCO2 and inorganic nutrients were made at three stations (seagrass beds, shallow bare sand and deep mud) in Lake Illawarra (Australia) to compare the characteristics of diagenesis and benthic biogeochemical processes for different primary producers (seagrass or microphytobenthos, (MPB)) and\\/or sediment types (sand or mud).Seagrass beds exhibited the highest gross primary productivity while the lowest

Wenchuan Qu; R. J. Morrison; R. J. West; Chenwei Su

2005-01-01

269

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

SciTech Connect

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

Stronkhorst, J.; Misdorp, R. (National Institute for Marine and Coastal Management, The Hague (Netherlands)); Vos, P.C. (Geological Survey of the Netherlands, Oosterwolde (Netherlands))

1994-06-01

270

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

Microsoft Academic Search

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

A. M. Winguth; C. Winguth

2010-01-01

271

Consequences of Increasing Hypoxic Disturbance on Benthic Communities and Ecosystem Functioning  

PubMed Central

Disturbance-mediated species loss has prompted research considering how ecosystem functions are changed when biota is impaired. However, there is still limited empirical evidence from natural environments evaluating the direct and indirect (i.e. via biota) effects of disturbance on ecosystem functioning. Oxygen deficiency is a widespread threat to coastal and estuarine communities. While the negative impacts of hypoxia on benthic communities are well known, few studies have assessed in situ how benthic communities subjected to different degrees of hypoxic stress alter their contribution to ecosystem functioning. We studied changes in sediment ecosystem function (i.e. oxygen and nutrient fluxes across the sediment water-interface) by artificially inducing hypoxia of different durations (0, 3, 7 and 48 days) in a subtidal sandy habitat. Benthic chamber incubations were used for measuring responses in sediment oxygen and nutrient fluxes. Changes in benthic species richness, structure and traits were quantified, while stress-induced behavioral changes were documented by observing bivalve reburial rates. The initial change in faunal behavior was followed by non-linear degradation in benthic parameters (abundance, biomass, bioturbation potential), gradually impairing the structural and functional composition of the benthic community. In terms of ecosystem function, the increasing duration of hypoxia altered sediment oxygen consumption and enhanced sediment effluxes of NH4+ and dissolved Si. Although effluxes of PO43? were not altered significantly, changes were observed in sediment PO43? sorption capability. The duration of hypoxia (i.e. number of days of stress) explained a minor part of the changes in ecosystem function. Instead, the benthic community and disturbance-driven changes within the benthos explained a larger proportion of the variability in sediment oxygen- and nutrient fluxes. Our results emphasize that the level of stress to the benthic habitat matters, and that the link between biodiversity and ecosystem function is likely to be affected by a range of factors in complex, natural environments. PMID:23091592

Villnäs, Anna; Norkko, Joanna; Lukkari, Kaarina; Hewitt, Judi; Norkko, Alf

2012-01-01

272

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

PubMed Central

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

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

2012-01-01

273

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)

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.

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

2014-05-01

274

Nitrogen budget of the northwestern Black Sea shelf inferred from modeling studies and in situ benthic measurements  

Microsoft Academic Search

A 3D eddy-resolving coupled biogeochemical-hydrodynamical model and in situ observations are used to investigate benthic processes on the Black Sea's NW shelf. Measurements of benthic fluxes (oxygen, nutrients, redox compounds) with in situ flux chambers are analyzed in regard to sediment dynamics on the shelf. The seasonal\\/interannual and spatial variability of benthic processes is explained in terms of 3D ecohydrodynamics.

M. Grégoire; J. Friedrich

2004-01-01

275

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

Microsoft Academic Search

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

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

2010-01-01

276

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

PubMed

Benthic diatoms evolved in a biofilm structure, at the interface between water and substrata. Biofilms can adsorb toxicants, such as herbicides, but little is known about the exposure of biofilm organisms, such as benthic diatoms, to these adsorbed herbicides. We assessed the sensitivity of 11 benthic diatoms species to 6 herbicides under both planktonic and benthic conditions using single-species bioassays. The concentration that reduced the growth rate of the population by 10% (EC10) and 50% (EC50), respectively, varied depending on the species, the herbicides, and the growth forms involved. As a general trend, the more hydrophobic the herbicide, the more species were found to be sensitive under benthic growth conditions. Statistical differences (alpha<5%) were observed between the sensitivities under planktonic and benthic growth conditions for many hydrophobic herbicides. A protective effect of the biofilm against herbicides was observed, and this tended to decrease (at both the EC10 and EC50 levels) with increasing hydrophobicity. The biofilm matrix appeared to control exposure to herbicides, and consequently their toxicity towards benthic diatoms. For metolachlor, terbutryn and irgarol, benthic thresholds derived from species sensitivity distributions were more protective than planktonic thresholds. For hydrophobic herbicides, deriving sensitivity thresholds from data obtained under benthic growth seems to offer a promising alternative. PMID:23831793

Larras, Floriane; Montuelle, Bernard; Bouchez, Agnès

2013-10-01

277

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

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

J. H. Baas; J. Schönfeld; R. Zahn

1998-01-01

278

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

NASA Astrophysics Data System (ADS)

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.

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

2012-10-01

279

Sensitivity of Heterogeneous Marine Benthic Habitats to Subtle Stressors  

PubMed Central

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

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

2013-01-01

280

Benthic foraminiferal microhabitat selection and sediment pore water geochemical gradients  

NASA Astrophysics Data System (ADS)

Benthic foraminiferal shell geochemistry has supplied proxies for a range of paleo-environmental variables. This geochemistry reflects the immediate microenvironment in which shell material is calcified. In many ways, the ideal, from a proxy point of view, would be that species consistently stratify themselves in the sediment column and that each records geochemical conditions from a particular depth. To evaluate the incorporation of geochemical proxies we examined habitats and geochemical conditions in marine sediments on the microscale experienced by the foraminifera. We used sites down the continental margin of the European Arctic where the only significant forcing variable was flux of organic carbon to the seabed. Multicores were maintained at in-situ conditions while we collected oxygen microprofiles, pore waters and micro-sampled for foraminifera. We used the geochemical data to define microenvironments directly where we collected foraminifera and to determine the local organic flux. We found that species abundance and distribution in the sediments was strongly influenced by the flux, as were the sedimentary geochemical gradients. However, species abundances and vertical distributions also were strongly influenced by the presence and structures of larger fauna. Foraminifera were most abundant where macrofauna were common and had bio-irrigated the sediments producing a complex mosaic of geochemical microenvironments. Species responded to this with variable distribution in the sediment profile, likely a result of seeking niches defined by chemical and biotic cues. This behavior could well explain such phenomena as the ‘Mackensen effect' in foraminiferal shell geochemistry.

Yavorska, Iryna; Loubere, Paul; Jacobsen, Brittani; Husum, Katrine

2010-05-01

281

Underwater locomotion strategy by a benthic pennate diatom Navicula sp.  

PubMed

The mechanism of diatom locomotion has been widely researched but still remains a hypothesis. There are several questionable points on the prevailing model proposed by Edgar, and some of the observed phenomena cannot be completely explained by this model. In this paper, we undertook detailed investigations of cell structures, locomotion, secreted mucilage, and bending deformation for a benthic pennate diatom Navicula species. According to these broad evidences, an updated locomotion model is proposed. For Navicula sp., locomotion is realized via two or more pseudopods or stalks protruded out of the frustules. The adhesion can be produced due to the pull-off of one pseudopod or stalk from the substratum through extracellular polymeric substances. And the positive pressure is generated to balance the adhesion because of the push-down of another pseudopod or stalk onto the substratum. Because of the positive pressure, friction is generated, acting as a driving force of locomotion, and the other pseudopod or stalk can detach from the substratum, resulting in the locomotion. Furthermore, this model is validated by the force evaluation and can better explain observed phenomena. This updated model would provide a novel aspect on underwater locomotion strategy, hence can be useful in terms of artificial underwater locomotion devices. PMID:23645345

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

2013-10-01

282

Effects of chemical disturbances on intertidal benthic assemblages.  

PubMed

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

Mayer-Pinto, Mariana; Ignacio, Barbara Lage

2015-02-15

283

Recent benthic ostracoda of Pahang River Delta, Pahang Darul Makmur  

NASA Astrophysics Data System (ADS)

A study on the distribution of recent benthic Ostracoda in marine sediment was carried out around Pahang River Delta, Pahang Darul Makmur. A total of 24 surface sediments were taken from the sampling stations between latitude 3°20' and 3°39'N and longitude 103°26' and 103°35'E. From this study, 71 species of ostracods belonging to 17 families and 42 genera were identified. The abundant and dominant species is Pontocypris virdis with 326 specimens obtained. The dominant family is Trachyleberididae (16 species, 585 specimens). The distribution of ostracoda is from 13 to 637 specimens. The species diversity is from 6 to 29 species. The diversity index, H(s) is in the range of 1.71 to 3.08. There are five common species (Hemicytheridea cancellata, Parakrithella australis, Propontocypris rostrata, Loxoconcha paiki and Lankacythere coralloides) in the study area. A comparison showed that a total of 53 species identified had been previously recorded in Malacca Straits, South China Sea and Java Sea. Five species are newly recorded in Malaysians waters. The species are Papillatabairdia elongata. Mimicocythere pseudomelobesoides, Kotoracythere doratus, Xestoleberis maculanitida and Bosasella profunda.

Noraswana, N. F.; Ramlan, O.

2014-09-01

284

Quantifying tidally driven benthic oxygen exchange across permeable sediments: An aquatic eddy correlation study  

NASA Astrophysics Data System (ADS)

shelves are predominately (˜70%) covered with permeable, sandy sediments. While identified as critical sites for intense oxygen, carbon, and nutrient turnover, constituent exchange across permeable sediments remains poorly quantified. The central North Sea largely consists of permeable sediments and has been identified as increasingly at risk for developing hypoxia. Therefore, we investigate the benthic O2 exchange across the permeable North Sea sediments using a combination of in situ microprofiles, a benthic chamber, and aquatic eddy correlation. Tidal bottom currents drive the variable sediment O2 penetration depth (from ˜3 to 8 mm) and the concurrent turbulence-driven 25-fold variation in the benthic sediment O2 uptake. The O2 flux and variability were reproduced using a simple 1-D model linking the benthic turbulence to the sediment pore water exchange. The high O2 flux variability results from deeper sediment O2 penetration depths and increased O2 storage during high velocities, which is then utilized during low-flow periods. The study reveals that the benthic hydrodynamics, sediment permeability, and pore water redox oscillations are all intimately linked and crucial parameters determining the oxygen availability. These parameters must all be considered when evaluating mineralization pathways of organic matter and nutrients in permeable sediments.

McGinnis, Daniel F.; Sommer, Stefan; Lorke, Andreas; Glud, Ronnie N.; Linke, Peter

2014-10-01

285

Subsurface unmixing for benthic habitat mapping using hyperspectral imagery and lidar-derived bathymetry  

NASA Astrophysics Data System (ADS)

Mapping of benthic habitats from hyperspectral imagery can be achieved by integrating bio-optical models with common techniques for hyperspectral image processing, such as spectral unmixing. Several algorithms have been described in the literature to compensate or remove the effects of the water column and extract information about the benthic habitat characteristics utilizing only measured hyperspectral imagery as input. More recently, the increasing availability of lidar-derived bathymetry information offers the possibility to incorporate this data into existing algorithms, thereby reducing the number of unknowns in the problem, for the improved retrieval of benthic habitat properties. This study demonstrates how bathymetry information improves the mapping of benthic habitats using two algorithms that combine bio-optical models with linear spectral unmixing. Hyperspectral data, both simulated and measured, in-situ spectral data, and lidar-derived bathymetry data are used for the analysis. The simulated data is used to study the capabilities of the selected algorithm to improve estimates of benthic habitat composition by combining bathymetry data with the hyperspectral imagery. Hyperspectral images captured over Emique in Puerto Rico using an AISA Eagle sensor is used to further test the algorithms using real data. Results from analyzing this imagery demonstrate increased agreement between algorithm output and existing habitat maps and ground truth when bathymetry data is used jointly with hyperspectral imagery.

Torres-Madronero, Maria C.; Velez-Reyes, Miguel; Goodman, James A.

2014-06-01

286

Ecological health monitoring of the Mekong River by using benthic algae in 2003-2004  

NASA Astrophysics Data System (ADS)

The monitoring of ecological health of the Mekong River by using benthic algae was carried out from 2003 - 2004. Thirty sampling sites along the Mekong River and its tributaries were selected in Laos, Thailand, Cambodia and Veitnam. In this investigation, the distribution of some species of benthic algae in different environments revealed that there was a significant relationship in the presence of them to the water quality, and these species could be used as a potential biomonitor of water quality in the Mekong River. One hundred and eighty six species of benthic diatoms and 46 species of macroalgae were found. Some dominant species of benthic algae could be used as biomonitors to assess water quality. Hydrodictyon recticulatum and Microspora floccosa and indicated clean-moderate water quality; Audouinella cylindrica, Cladophora glomerata, Achnanthes inflate and Cymbella turgidula indicated moderate water quality; Stigeoclonium flagelliforum, Aulacoseira granulata and Cymbella tumida indicated moderate-polluted water quality and Caloglossa leprieurii, Gomphonema parvulum and Nitzschia clausii indicated polluted water quality. The ecological health assessment of the Mekong River by using the species of benthic algae as biomonitors reveled that in the upstream and tributaries revealed moderate water quality. In contrast, some sites in the lower Mekong showed moderate-polluted to polluted water quality.

Kunpradid, T.

2005-05-01

287

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

USGS Publications Warehouse

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)

Bradfield, A.D.

1986-01-01

288

Effects of Stream Fishes on Benthic Primary Productivity: A Mechanistic Test  

NASA Astrophysics Data System (ADS)

I simultaneously tested three alternative hypotheses (the trophic cascade, nutrient enhancement via terrestrial nutrient translocation, and nutrient enhancement via bioturbation) for consumer regulation of primary productivity (PPR) by three widely distributed stream fish species (Orangethroat Darter, Western Mosquitofish, and Bullhead Minnow). I used stream mesocosms fitted with fish and terrestrial input barriers to address relative importance of localized fish predation versus access to terrestrial inputs for fish consumer effects. Orangethroat Darter, a benthic invertivore, increased PPR through an apparent trophic cascade, by localized reduction of benthic grazing invertebrate densities. Western mosquitofish, a surface feeding insectivore, increased PPR by enhancing nutrients through terrestrial nutrient translocation, and had no effect on benthic grazer invertebrate density. Bullhead Minnow, a benthic omnivore that disturbed sediments during foraging, increased PPR through nutrient enhancement via bioturbation, but within specific stream mesocosm areas two which the fish was restricted it also reduced benthic grazing invertebrates. Thus, suggesting this species may have affected PPR through a combination bioturbation and trophic cascade mechanisms. These mechanistic pathways are likely common processes by which fish affect food web structure and ecosystem function in many stream ecosystems.

Hargrave, C. W.

2005-05-01

289

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

PubMed Central

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

Buesing, Nanna; Gessner, Mark O.

2006-01-01

290

Benthic substrate classification map: Gulf Islands National Seashore  

USGS Publications Warehouse

The 2005 hurricane season was devastating for the Mississippi Gulf Coast. Hurricane Katrina caused significant degradation of the barrier islands that compose the Gulf Islands National Seashore (GUIS). Because of the ability of coastal barrier islands to help mitigate hurricane damage to the mainland, restoring these habitats prior to the onset of future storms will help protect the islands themselves and the surrounding habitats. During Hurricane Katrina, coastal barrier islands reduced storm surge by approximately 10 percent and moderated wave heights (Wamsley and others, 2009). Islands protected the mainland by preventing ocean waves from maintaining their size as they approached the mainland. In addition to storm protection, it is advantageous to restore these islands to preserve the cultural heritage present there (for example, Fort Massachusetts) and because of the influence that these islands have on marine ecology. For example, these islands help maintain a salinity regime favorable to oysters in the Mississippi Sound and provide critical habitats for many migratory birds and endangered species such as sea turtles (Chelonia mydas, Caretta caretta, and Dermochelys coriacea), Gulf sturgeon (Acipenser oxyrinchus desotoi), and piping plovers (Charadrius melodus) (U.S. Army Corps of Engineers, 2009a). As land manager for the GUIS, the National Park Service (NPS) has been working with the State of Mississippi and the Mobile District of the U.S. Army Corps of Engineers to provide a set of recommendations to the Mississippi Coastal Improvements Program (MsCIP) that will guide restoration planning. The final set of recommendations includes directly renourishing both West Ship Island (to protect Fort Massachusetts) and East Ship Island (to restore the French Warehouse archaeological site); filling Camille Cut to recreate a continuous Ship Island; and restoring natural regional sediment transport processes by placing sand in the littoral zone just east of Petit Bois Island. Prevailing sediment transport processes will provide natural renourishment of the westward islands in the barrier system (U.S. Army Corps of Engineers, 2009b). One difficulty in developing the final recommendations is that few data are available to incorporate into restoration plans related to bathymetry, sediment type, and biota. For example, the most recent bathymetry available dates to when East and West Ship Islands were a single continuous island (1917). As a result, the MsCIP program has encouraged post-hurricane bathymetric data collection for future reference. Furthermore, managing a complex environment such as this barrier island system for habitat conservation and best resource usage requires significant knowledge about those habitats and resources. To effectively address these issues, a complete and comprehensive understanding of the type, geographic extent, and condition of marine resources included within the GUIS is required. However, the data related to the GUIS marine resources are limited either spatially or temporally. Specifically, there is limited knowledge and information about the distribution of benthic habitats and the characteristics of the offshore region of the GUIS, even though these are the habitats that will be most affected by habitat restoration. The goal of this project is to develop a comprehensive map of the benthic marine habitats within the GUIS to give park managers the ability to develop strategies for coastal and ocean-resource management and to aid decisionmakers in evaluating conservation priorities.

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

2013-01-01

291

Benthic invertebrate bioassays with toxic sediment and pore water  

USGS Publications Warehouse

The relative sensitivities of bioassays to determine the toxicity of sediments were investigated and three methods of making the sample dilutions required to generate dose-response relationships were compared. The assays studied were: (a) Microtox(R), a 15-min assay of Photobacterium phosphoreum bioluminescence inhibition by pore water; (b) 48-h Daphnia magna lethality test in pore water; (c) 10-d subchronic assay of lethality to and reduction of weight gain by Chironomus tentans performed in either whole sediment or pore water; (d) 168-h acute lethality assay of Hexagenia limbata in either whole sediment or pore water. The three methods of diluting sediments were: (a) extracting pore water from the toxic location and dilution with pore water from the control station; (b) diluting whole sediment from the toxic location with control whole sediment from a reference location, then extracting pore water; and (c) diluting toxic, whole sediment with whole sediment from a reference location, then using the whole sediment in bioassays. Based on lethality, H. limbata was the most sensitive organism to the toxicity of Detroit River sediment. Lethality of D. magna was similar to that of H. limbata in whole sediment and can be used to predict effects of whole sediment toxicity to H. limbata. The concentration required to cause a 50% reduction in C. tentans growth (10-d EC50) was approximately that which caused 50% lethality of D. magna (48-h LC50) and was similar to the toxicity that restricts benthic invertebrate colonization of contaminated sediments. While the three dilution techniques gave similar results with some assays, they gave very different results in other assays. The dose-response relationships determined by the three dilution techniques would be expected to vary with sediment, toxicant and bioassay type, and the dose-response relationship derived from each technique needs to be interpreted accordingly.

Giesy, John P.; Rosiu, Cornell J.; Graney, Robert L.; Henry, Mary G.

1990-01-01

292

Biological vs. physical mixing effects on benthic food web dynamics.  

PubMed

Biological particle mixing (bioturbation) and solute transfer (bio-irrigation) contribute extensively to ecosystem functioning in sediments where physical mixing is low. Macrobenthos transports oxygen and organic matter deeper into the sediment, thereby likely providing favourable niches to lower trophic levels (i.e., smaller benthic animals such as meiofauna and bacteria) and thus stimulating mineralisation. Whether this biological transport facilitates fresh organic matter assimilation by the metazoan lower part of the food web through niche establishment (i.e., ecosystem engineering) or rather deprives them from food sources, is so far unclear. We investigated the effects of the ecosystem engineers Lanice conchilega (bio-irrigator) and Abra alba (bioturbator) compared to abiotic physical mixing events on survival and food uptake of nematodes after a simulated phytoplankton bloom. The (13)C labelled diatom Skeletonema costatum was added to 4 treatments: (1) microcosms containing the bioturbator, (2) microcosms containing the bio-irrigator, (3) control microcosms and (4) microcosms with abiotic manual surface mixing. Nematode survival and subsurface peaks in nematode density profiles were most pronounced in the bio-irrigator treatment. However, nematode specific uptake (??(13)C) of the added diatoms was highest in the physical mixing treatment, where macrobenthos was absent and the diatom (13)C was homogenised. Overall, nematodes fed preferentially on bulk sedimentary organic material rather than the added diatoms. The total C budget (µg C m(-2)), which included TO(13)C remaining in the sediment, respiration, nematode and macrobenthic uptake, highlighted the limited assimilation by the metazoan benthos and the major role of bacterial respiration. In summary, bioturbation and especially bio-irrigation facilitated the lower trophic levels mainly over the long-term through niche establishment. Since the freshly added diatoms represented only a limited food source for nematodes, the macrobenthic effect was more pronounced in niche establishment than the negative structuring effects such as competition. PMID:21455308

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

2011-01-01

293

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

PubMed

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

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

2009-02-01

294

Similarity & Instability in Flows Over Permeable Layers (Invited)  

NASA Astrophysics Data System (ADS)

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

Ghisalberti, M.

2013-12-01

295

CHANGES IN THE FRESHWATER BENTHIC COMMUNITY OF LAKE ONTARIO SINCE THE INVASION OF DREISSENA 1972-1997  

EPA Science Inventory

Population changes of three major benthic taxa are discussed in relation to Dreissena spp. Lake Ontario was sampled pre-invasion (1972) and post-invasion (1994, 1997) for abundance of benthic organisms. In offshore sediments of Lake Ontario, neither species composition nor abunda...

296

Effect of natural populations of burrowing thalassinidean shrimp on sediment irrigation, benthic metabolism, nutrient fluxes and denitrification  

Microsoft Academic Search

The aim of this study was to determine the effect of burrowing by natural populations of Trypaea australiensis on benthic metabolism, nutrient flux, denitrification and irrigation rates using in situ benthic chambers and exclusion nets to minimise disturbance and associated artefacts. The burrows of T. australiensis enhanced total sediment porewater exchange rates 5-fold compared to uninhabited sediments. Calculated single-burrow flow

Arthur P Webb; Bradley D Eyre

2004-01-01

297

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

Microsoft Academic Search

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

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

2006-01-01

298

Recent changes in benthic macroinvertebrate populations in Lake Huron and impact on the diet of lake whitefish (coregonus clupeaformis)  

Microsoft Academic Search

Surveys of the benthic macroinvertebrate community were conducted in the main basin of Lake Huron in 2000 and 2003, and corresponding studies of lake whitefish diets were conducted in 2002-2004. Populations of three major benthic taxa, Diporeia spp., Sphaeriidae, and Chironomidae, declined dramatically between 2000 and 2003, with densities declining 57%, 74%, and 75% over this 3-year period. By 2003,

Thomas F. Nalepa; Steven A. Pothoven; David L. Fanslow

2009-01-01

299

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...

300

Epiphyton as a niche for ammonia-oxidizing bacteria: detailed comparison with benthic and pelagic compartments in shallow freshwater lakes  

Microsoft Academic Search

Next to the benthic and pelagic compartments, the epiphyton of submerged macrophytes may offer an additional niche for ammonia-oxidizing bacteria in shallow freshwater lakes. In this study, we explored the potential activities and community compositions of ammonia-oxidizing bacteria of the epiphytic, benthic, and pelagic compartments of seven shallow freshwater lakes which differed in their trophic status, distribution of submerged macrophytes,

M. Coci; P. L. E. Bodelier; H. J. Laanbroek

2008-01-01

301

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...

302

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

E-print Network

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...

O'Neill, Brian James

2010-04-02

303

Bacteria and Foraminifera: key players in a short-term deep-sea benthic response to phytodetritus  

Microsoft Academic Search

The deep-sea floor has long been considered a 'food desert' but recent observations suggest that episodic inputs of relatively fresh organic matter (phytodetritus) occur and that benthic processing of this material may be rapid. Although the responses of the total community in terms of oxygen consumption and of some individual benthic groups have been identified, the quantitative role of the

L. Moodley; J. J. Middelburg; H. T. S. Boschker; GCA Duineveld; R. Pel; P. M. J. Herman; C. H. R. Heip

2002-01-01

304

Spatial variation in organic matter utilization by benthic communities from Yura River-Estuary to offshore of Tango Sea, Japan  

NASA Astrophysics Data System (ADS)

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.

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

2010-01-01

305

Persistent organic pollutants in benthic and pelagic organisms off Adélie Land, Antarctica.  

PubMed

The concentrations of polychlorinated biphenyls (PCB), hexachlorobenzene (HCB), pentachlorobenzene (PeCB) and polybrominated diphenylethers (PBDE) were described in benthic and pelagic species collected off Adélie Land, Antarctica. Strong differences were observed among species, with reduced PeCB and HCB levels in benthic species, and elevated PCB levels in the Antarctic yellowbelly rockcod, the Antarctic sea urchin and the snow petrel. Lower-chlorinated congeners were predominant in krill; penta-PCBs in benthic organisms; hexa- and hepta-PCBs in seabirds and cryopelagic fish. This segregation may result from sedimentation process, specific accumulation and excretion, and/or biotransformation processes. The presence of PBDEs in Antarctic coastal organisms may originate from atmospheric transport and partly from a contamination by local sources. Although POP levels in Antarctic marine organisms were substantially lower than in Arctic and temperate organisms, very little is known about their toxic effects on these cold-adapted species, with high degree of endemism. PMID:24237994

Goutte, A; Chevreuil, M; Alliot, F; Chastel, O; Cherel, Y; Eléaume, M; Massé, G

2013-12-15

306

Benthic foraminifera show some resilience to ocean acidification in the northern Gulf of California, Mexico.  

PubMed

Extensive CO2 vents have been discovered in the Wagner Basin, northern Gulf of California, where they create large areas with lowered seawater pH. Such areas are suitable for investigations of long-term biological effects of ocean acidification and effects of CO2 leakage from subsea carbon capture storage. Here, we show responses of benthic foraminifera to seawater pH gradients at 74-207m water depth. Living (rose Bengal stained) benthic foraminifera included Nonionella basispinata, Epistominella bradyana and Bulimina marginata. Studies on foraminifera at CO2 vents in the Mediterranean and off Papua New Guinea have shown dramatic long-term effects of acidified seawater. We found living calcareous benthic foraminifera in low pH conditions in the northern Gulf of California, although there was an impoverished species assemblage and evidence of post-mortem test dissolution. PMID:23473095

Pettit, L R; Hart, M B; Medina-Sánchez, A N; Smart, C W; Rodolfo-Metalpa, R; Hall-Spencer, J M; Prol-Ledesma, R M

2013-08-30

307

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

PubMed

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

Aloulou, Fatma; EllEuch, Boubaker; Kallel, Monem

2012-01-01

308

Evaluation of potential relationships between benthic community structure and toxic metals in Laizhou Bay.  

PubMed

The objective of the present study was to examine the relationships between benthic community structure and toxic metals using bivariate/multivariate techniques at 17 sediment locations in Laizhou Bay, North China. Sediment chemical data were evaluated against geochemical background values and sediment quality guidelines, which identified Cu and As as contaminants of concern with a moderate potential for adverse effects. Benthic community data were subjected to non-metric multidimensional scaling, which generated four groups of stations. Spearman rank correlation was then employed to explore the relationships between the major axes of heavy metals and benthic community structure. However, weak and insignificant correlations were found between these axes, indicating that contaminants of concern may not be the primary explanatory factors. Polychaeta were abundant in southern Laizhou Bay, serving as a warning regarding the health status of the ecosystem. Integrated sediment quality assessment showed sediments from northern central locations were impaired, displaying less diverse benthos and higher metal contamination. PMID:25113101

Wu, Bin; Song, Jinming; Li, Xuegang

2014-10-15

309

Threshold response of benthic macrofauna integrity to metal contamination in West Greenland.  

PubMed

Sediment metal chemistry and benthic infauna surveys have been conducted over 33 years following a BACI protocol in relation to submarine tailings deposition (STD) from a lead-zinc mine in a western Greenland fjord system. We found clear predictable changes of benthic fauna composition in response to STD both temporally and spatially. Faunal re-colonization 15 years after mine closure, was slow and the impacted areas were still dominated by opportunistic species, although the most opportunistic ones (e.g. Capitella species) had decreased in importance. Concentration-response relations between sediment lead and faunal indices of benthic community integrity (e.g. the AMBI and DKI indices) indicated a threshold of ca. 200mg/kg, above which deterioration of faunal communities occurred. Above this threshold, diversity decreased dramatically and dominance of sensitive and indifferent species was substituted by tolerant or opportunistic species. Disposal of metal contaminated tailings may have long lasting effects on the biological system. PMID:18513757

Josefson, A B; Hansen, J L S; Asmund, G; Johansen, P

2008-07-01

310

Benthic recovery during open sea fish farming abatement in Western Mediterranean, Spain.  

PubMed

Fish farming is an important source of organic matter input in coastal waters, which contributes to eutrophication. In this study, the macrofaunal benthic community was studied after the cessation of fish farming with the aim of improving our understanding of benthic succession and sediment recovery in a marine ecosystem. The results showed that the best environmental variables for assessing organic pollution were acid-volatile sulfides (AVS) and redox potential. Succession and recovery was best explained by macrofaunal analysis based on community composition as well as on trophic groups. The patterns of recovery differed between each impacted station. For this reason, succession could not be accurately predicted due to the unique environmental parameters and the singular community functional structure of each location. The Azti Marine Benthic Index (AMBI) proved its validity for assessing pollution but did not distinguish between successional stages. PMID:16890280

Sanz-Lázaro, Carlos; Marin, Arnaldo

2006-12-01

311

Multiscale patterns in the diversity and organization of benthic intertidal fauna among French Atlantic estuaries  

NASA Astrophysics Data System (ADS)

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.

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

312

Necrophagy by a benthic omnivore influences biomagnification of methylmercury in fish.  

PubMed

Omnivory has an important role in the movement of energy, nutrients, and contaminants between benthic and pelagic food webs. While top-predator fish are known to supplement a mostly piscivorous diet with benthic organisms, a more obscure benthic-pelagic coupling occurs when benthic invertebrates forage on fish carcasses, referred to as necrophagy. The combination of these two benthic-pelagic links, top-predator fish feeding on benthic organisms that have fed on dead fish, can generate a trophic feedback cycle that conserves energy and nutrients and may have implications for biomagnification of methylmercury (MeHg) in fish. We investigated the role of necrophagy by crayfish (Procambarus clarkii), via a trophic feedback cycle, on the biomagnification of MeHg in largemouth bass (Micropterus salmoides), a cosmopolitan top predator fish known to feed on crayfish. Controlled laboratory tests quantified the uptake of MeHg by both organisms from artificial and natural food (whole crayfish or bass tissue). Assimilation efficiency (AE) of MeHg was greater for bass fed crayfish (79±0.5%) than those fed artificial food (60±3%). Furthermore, AE of MeHg was greatest for largemouth bass fed crayfish that fed on MeHg-dosed dead fish (i.e., trophic feedback cycle; 94±17%). A model, parameterized with results of the laboratory experiments, was used to make steady-state projections of MeHg biomagnification factors. Model projections also indicate that MeHg biomagnification would be greatest for largemouth bass from a trophic feedback cycle. These results suggest that food web ecology has an important role in determining MeHg levels in predatory fish and underscore the need for further investigation into the magnitude that necrophagy may affect MeHg biomagnification in aquatic systems. PMID:21356175

Bowling, Anna M; Hammerschmidt, Chad R; Oris, James T

2011-04-01

313

Effects of Management Legacies on Stream Fish and Aquatic Benthic Macroinvertebrate Assemblages  

NASA Astrophysics Data System (ADS)

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.

Quist, Michael C.; Schultz, Randall D.

2014-09-01

314

Crater lake cichlids individually specialize along the benthic–limnetic axis  

PubMed Central

A common pattern of adaptive diversification in freshwater fishes is the repeated evolution of elongated open water (limnetic) species and high-bodied shore (benthic) species from generalist ancestors. Studies on phenotype-diet correlations have suggested that population-wide individual specialization occurs at an early evolutionary and ecological stage of divergence and niche partitioning. This variable restricted niche use across individuals can provide the raw material for earliest stages of sympatric divergence. We investigated variation in morphology and diet as well as their correlations along the benthic-limnetic axis in an extremely young Midas cichlid species, Amphilophus tolteca, endemic to the Nicaraguan crater lake Asososca Managua. We found that A. tolteca varied continuously in ecologically relevant traits such as body shape and lower pharyngeal jaw morphology. The correlation of these phenotypes with niche suggested that individuals are specialized along the benthic-limnetic axis. No genetic differentiation within the crater lake was detected based on genotypes from 13 microsatellite loci. Overall, we found that individual specialization in this young crater lake species encompasses the limnetic-as well as the benthic macro-habitat. Yet there is no evidence for any diversification within the species, making this a candidate system for studying what might be the early stages preceding sympatric divergence. A common pattern of adaptive diversification in freshwater fishes is the repeated evolution of open water (limnetic) species and of shore (benthic) species. Individual specialization can reflect earliest stages of evolutionary and ecological divergence. We here demonstrate individual specialization along the benthic–limnetic axis in a young adaptive radiation of crater lake cichlid fishes. PMID:24772288

Kusche, Henrik; Recknagel, Hans; Elmer, Kathryn Rebecca; Meyer, Axel

2014-01-01

315

Effects of management legacies on stream fish and aquatic benthic macroinvertebrate assemblages.  

PubMed

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. PMID:24981272

Quist, Michael C; Schultz, Randall D

2014-09-01

316

Benthic foraminifera as indicators of pollution in high latitude marine environments  

NASA Astrophysics Data System (ADS)

An increasing number of studies demonstrate the potential of benthic foraminifera to characterize ecological status. However, the use of benthic foraminifera as bio-indicators has previously not been tested in high latitudes. This research contributes to the development of foraminifera as a bio-monitoring technique for the Arctic region, as industrial activities in this region will increase in the coming years. Surface sediments (0-1 cm) from sites close to gas fields in the SW Barents Sea were studied. In addition, to elucidate the range from less to very affected, surface sediments from the harbor of the town of Hammerfest (70° N) were studied. At least 300 living benthic foraminifera from the size fraction 100 µm-1 mm were counted and identified at species level. Pollution levels (heavy metals and persistent organic pollutants) and sediment properties (grainsize and TOC) were also analyzed. Pollution levels at the sea floor in the SW Barents Sea are of background to good level (level I-II) according to the definitions by the Water Framework Directorate (WFD). Benthic foraminiferal assemblages are influenced by natural environmental parameters such as water mass properties, water depth, nutrient availability, bottom current strength, and grain size. Surface sediments from the Hammerfest harbor are of moderate environmental status (WFD level II-III) based on heavy metal concentrations and of bad environmental status (WFD IV-V) based on persistent organic pollutant concentrations. Opportunistic benthic foraminifera are dominating the assemblages. The most polluted areas in the harbor are barren for foraminifera or have high amounts of deformed shells. In both environments the foraminiferal diversity of the samples, does not correspond to expected environmental status based on the pollution levels of the sediments. Environmental status classes, based on benthic foraminifera instead of macrofauna, would allow rapid analyses of the environmental impact of pollution.

Dijkstra, N.; Junttila, J.; Husum, K.; Carroll, J.; Klitgaard-Kristensen, D.; Hald, M.

2012-04-01

317

Sequential sampling: cost-effective approach for monitoring benthic macroinvertebrates in environmental impact assessements  

SciTech Connect

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.

Resh, V.H.; Price, D.G.

1984-01-01

318

Correspondence of stream benthic invertebrate assemblages to regional classification schemes in Missouri  

USGS Publications Warehouse

Benthic invertebrates from 44 reference streams throughout the state of Missouri were examined for their concordance with established regionalization systems, both aquatic and terrestrial. Invertebrate assemblages coincided nicely with Pflieger's established aquatic faunal regions system, expanding its generality to more than fish assemblages. Our benthic invertebrate and Pflieger's fish assemblages coincided well with both Bailey's ecological sections and Omernik's ecoregions. Subregionalization using Pflieger's subregions and Bailey's subsections further reduced unexplained variation and is recommended for use wherever possible. The concordance of the aquatic fauna and terrestrial features implies the possibility of coordinated regional management among different natural resource disciplines.

Rabeni, C.F.; Doisy, K.E.

2000-01-01

319

Nutrient Retention by Benthic Macrofaunal Biomass of Danish Estuaries: Importance of Nutrient Load and Residence Time  

NASA Astrophysics Data System (ADS)

The response of macrobenthic faunal abundance and biomass to nutrient load, and factors that may modify this response are examined by means of inter-estuary comparisons of 14 shallow Danish estuaries. Data for this analysis are the physicochemical and biological variables monitored by local authorities mainly during the period 1989-95. A clear positive effect of nutrient load is demonstrated on benthic biomass, over a wide range of total N-load as the model substance from 2-200 g m -2year -1. The relationship was curvilinear with a levelling off or even depression of biomass at high total N-load (above c. 35 g m -2year -1). A mixed chemostat model using total load and hydraulic residence time for estuaries was applied to estimate the load that could be realized into primary production, and consequently enter into benthic production. Two measures, the load corrected for winter export (the realized N-load) and the nutrient pool available for the spring bloom (SBNP) were calculated. The benthic metabolic demand inferred from biomass, assuming an annual P:B ratio of 1 (P, secondary production; B, benthic biomass), was approximately of the same magnitude as both total N-load and realized N-load. A positive correlation was still found between benthic biomass/production and the realized N-load, but the linearity of the regression between them was not improved compared to the corresponding relationship with total load. The best linearly proportional relationship was obtained with the spring bloom N-pool (SBNP) calculated from the chemostat model. Stoichiometry suggested, however, that the spring bloom is of little importance for supporting benthic standing stock in these well flushed estuaries. To explain the strong statistical relationship, despite poor causality, with SBNP, it is suggested that the algorithm behind SBNP reflects the ability of the estuary to retain nutrients in the water mass in the productive period, both as free molecules and included into biological particles. These findings strongly indicate that benthic standing stock system-wide is food limited and indicate the importance of interaction between loading and estuary residence time (flushing) for the outcome of eutrophication. The findings are in agreement with reports that high estuary flushing rate may modify effects of eutrophication, and they deviate from previous studies in shallow coastal areas reporting either no effect, or negative effects, of eutrophication on benthic biomass.

Josefson, A. B.; Rasmussen, B.

2000-02-01

320

Distribution and abundance of benthic organisms in the Sacramento River, California  

USGS Publications Warehouse

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)

Ferreira, Rodger F.; Green, D. Brady

1977-01-01

321

Interactions between benthic predators and zooplanktonic prey are affected by turbulent waves.  

PubMed

Predators capture prey in complex and variable environments. In the ocean, bottom-dwelling (benthic) organisms are subjected to water currents, waves, and turbulent eddies. For benthic predators that feed on small animals carried in the water (zooplankton), flow not only delivers prey, but can also shape predator-prey interactions. Benthic passive suspension feeders collect prey delivered by movement of ambient water onto capture-surfaces, whereas motile benthic predators, such as burrow-dwelling fish, dart out to catch passing zooplankton. How does the flow of ambient water affect these contrasting modes of predation by benthic zooplanktivores? We studied the effects of turbulent, wavy flow on the encounter, capture, and retention of motile zooplanktonic prey (copepods, Acartia spp.) by passive benthic suspension feeders (sea anemones, Anthopleura elegantissima). Predator-prey interactions were video-recorded in a wave-generating flume under two regimes of oscillating flow with different peak wave velocities and levels of turbulent kinetic energy ("weak" and "strong" waves). Rates of encounter (number of prey passing through a sea anemone's capture zone per time), capture (prey contacting and sticking to tentacles per time), and retention (prey retained on tentacles, without struggling free or washing off, per time) were measured at both strengths of waves. Strong waves enhanced encounter rates both for dead copepods and for actively swimming copepods, but there was so much variability in the behavior of the live prey that the effect of wave strength on encounter rates was not significant. Trapping efficiency (number of prey retained per number encountered) was the same in both flow regimes because, although fewer prey executed maneuvers to escape capture in strong waves, more of the captured prey was washed off the predators' tentacles. Although peak water velocities and turbulence of waves did not affect feeding rates of passive suspension-feeding sea anemones, increases in these aspects of flow have been shown to enhance feeding rates and efficiency of motile benthic fish that lunge out of their burrows to catch zooplankton. Faster, more turbulent flow interferes with the ability of prey to detect predators and execute escape maneuvers, and thus enhances capture rates both for passive suspension-feeding predators and for actively swimming predators. However, prey captured in the mouths of fish are not washed away by ambient flow, whereas prey captured on the tentacles of suspension feeders can be swept off before they are ingested. Therefore, the effects of flowing water on predation on zooplankton by benthic animals depend on the feeding mode of the predator. PMID:23942646

Robinson, H E; Finelli, C M; Koehl, M A R

2013-11-01

322

Effects of gut sediment contents on measurements of metal levels in benthic invertebrates - a cautionary note  

SciTech Connect

Studies of heavy metal levels in benthic organisms typically do not correct for gut sediment metal levels other than by allowing a period of depuration in clean water. The effectiveness of depuration has recently been questioned in British Columbia in the particular case of the marine clam Yoldia. In light of this controversy, it appears appropriate to present data from a study of heavy metal levels in sediments and benthic organisms in the Lower Fraser River, BC, regarding the effects of gut sediment contents.

Chapman, P.M.

1985-09-01

323

Multiple tube sampler for benthic and pelagic invertebrates in shallow wetlands  

USGS Publications Warehouse

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.

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

1992-01-01

324

Benthic infaunal community structuring in an acidified tropical estuarine system  

PubMed Central

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

2014-01-01

325

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

USGS Publications Warehouse

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).

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

2014-01-01

326

Benthic habitat mapping: Concerns using a combined approach (acoustic, sediment and biological data)  

NASA Astrophysics Data System (ADS)

Near-shore benthic biotopes, in the 2-30 m depth range, were analyzed and mapped using a combination of biological, sedimentary and acoustic data to interrogate the utility of these methods. The surveyed area covered approximately 270 km 2, along 80 km of the Southeast coast of Portugal. The acoustic data were acquired with a single beam ground discrimination system (QTC VIEW, Series V), connected to a dual frequency echo sounder (50 and 200 kHz). Sediment grain size and macrofaunal community data were obtained by grab sampling at 88 sites. The sedimentary and the biological data were subjected to classification and ordination analysis and the acoustic data obtained with the two frequencies were analyzed individually with the QTC IMPACT (v3.4) software and classified into acoustic classes. The affinity groups obtained with the three datasets were mapped using a Geographic Information System. The study area showed an inshore-offshore pattern with sands ranging from very fine to very coarse, revealing a sediment distribution in the near-shore shelf comprised by two main areas; a very fine/fine sand area up to 7-10 m depth and a very coarse/coarse sand area offshore. In turn, the biological data also showed an inshore-offshore pattern, identifying two main biological assemblages: fine/very fine sand and coarse/very coarse sand communities. Furthermore, the biological pattern clearly reflected the hydrodynamic conditions of the area, from highly hydrodynamic shallow depth to the calmer deeper areas. Accordingly, species richness and densities were lower at shallow areas than at deeper depth. The acoustic data identified the prevailing biosedimentary gradients along the inshore-offshore direction. Overall, the results obtained here showed that the acoustic system could identify two main areas based on sediment grain size, which closely related to the two main biological communities (groups A and B). This study indicates the importance of combining several layers of information in order to increase the spatial resolution of the main biotope distribution (validating the acoustic data) and detail their sub-divisions (ground-truth sampling). Furthermore, we show that designing ground-truth samples on the basis of the acoustic diversity data allows the biological data to "speak" for itself. In general, acoustic techniques are used as a means to optimize ground-truth sampling. This will only be valid if acoustics can capture all the essence of biotope heterogeneity. If this is not the case, special attention should be given when using broad scale methods (acoustic remote sensing) devoted to biotope mapping.

Freitas, Rosa; Ricardo, Fernando; Pereira, Fábio; Sampaio, Leandro; Carvalho, Susana; Gaspar, Miguel; Quintino, Victor; Rodrigues, Ana Maria

2011-05-01

327

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

E-print Network

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

Thuesen, Erik V.

328

Drift and benthic invertebrate responses to stepwise and abrupt increases in non-scouring flow  

Microsoft Academic Search

We conducted two experiments to assess drift and benthic invertebrate responses to stepwise and abrupt changes in non-scouring flow in gravel-bed experimental streams. Intuitively, a stepwise flow increase should allow aquatic invertebrates more time to seek refuges than would an abrupt increase. We hypothesized that abrupt flow increases would result in larger increases in taxon richness and in the number

J. Bosco Imbert; James A. Perry

2000-01-01

329

EFFECTS OF 4-NONYLPHENOL ON BENTHIC MACROINVERTEBRATES AND INSECT EMERGENCE IN LITTORAL ENCLOSURES  

EPA Science Inventory

The effect of 4-nonylphenol (NP) on benthic, freshwater marcroinvertebrates in littoral enclosures was evaluated over a two-year period. Enclosures received 11 NP applications, 48 h apart, with nominal ratres of 3,30, 100, and 300 ?g/L....

330

Relationships between stripmining-induced changes and benthic insect communities in the southern Appalachian Region  

SciTech Connect

Increased demands for coal to supply America's energy needs, as well as the controversy surrounding the requirements and enforcement of the Surface Mining Control and Reclamation Act of 1977, point directly to the need for determination of specific factors associated with stripmining alteration that produce major environmental impacts. Numerous studies have demonstrated physical and chemical alterations to southern Appalachian streams subject to stripmining effluents found that the two major factors resulting in physical alterations were increased runoff and resultant sedimentation. Studies in streams receiving acid mine drainage showed that benthic insect communities differed in undisturbed and stripmining disturbed streams. Branson and Batch noted differences in benthic communities in Kentucky streams disturbed by non-acid stripmining. Tolbert found significant differences in benthic communities between undisturbed and nonacid mining streams. This paper describes research to determine what stripmining-altered parameters are responsible for differences in benthic insect communities. The results of this study can be applied toward validation of control measures required by the Surface Mining Control and Reclamation Act.

Tolbert, V.R.

1980-01-01

331

Impact of nanoflagellate bacterivory on benthic bacterial production in the North Sea  

Microsoft Academic Search

In situ grazing of benthic heterotrophic nanoflagellates on bacteria was studied in a wide range of sediment types in the North Sea during summer and winter. Grazing rates were measured using the fluorescently labelled bacteria (FLB) technique. Several factors may potentially influence flagellate grazing, viz. temperature, sediment grain size, bacterial abundance and production, flagellate abundance and biovolume. Flagellate grazing rates

Bea J. M. Hondeveld; Gerard Nieuwland; Fleur C. Van Duyl; Rolf P. M. Bak

1995-01-01

332

Benthic Bacterial Production and Protozoan Predation in a Silty Freshwater Environment  

Microsoft Academic Search

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

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

2003-01-01

333

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,...

334

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...

335

Quantitative multivariate analytical strategy for paleoenvironmental analysis of mixed benthic foraminiferal assemblages  

Microsoft Academic Search

Fossil assemblages of benthic foraminifera commonly contain taxa that were not associated together during life. A variety of processes act to modify living assemblages during the transition to fossil assemblages-transport of tests by traction and gravity currents, taphonomic filtering, and rapid shifting of environments in response to sea level fluctuations, to name a few. Unraveling the nature of faunal mixing

1991-01-01

336

Selenium in sediments, pore waters and benthic infauna of Lake Macquarie, New South Wales,  

E-print Network

Applied Ecology, University of Canberra, Canberra ACT 2601, Australia c New South Wales Environment-6-201-2531; fax: +61-6-210-5305; e-mail: maher@science. canberra.edu.au #12;these data suggest that benthic food

Canberra, University of

337

A comparison of benthic macroinvertebrate assemblages among different types of alpine streams  

Microsoft Academic Search

SUMMARY 1. Benthic macroinvertebrate assemblages were compared among a diverse array of first- order alpine tundra streams of the Swiss Alps. 2. A principal components analysis separated sites into three main groups: rhithral streams, rhithral lake outlets, and kryal sites including outlets and streams. Rhithral streams contained the most diverse and taxon rich assemblages, being colonised by both non-insect taxa

MAGGI H IEBER; C HRISTOPHER T. R OBINSON; URS U EHLINGER

338

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

E-print Network

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

Benstead, Jon

339

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

340

Periphyton As A Source Of Bioavailable Cd and Cu To Invertebrate Benthic Grazers  

Microsoft Academic Search

High metal body burdens observed in invertebrate benthic grazers suggest that periphyton is an important source of bioavailable metals. We conducted comparative studies among five species of stream insects (the mayflies Nixe sp., Epeorus albertae, E. longimanus, Serratella tibialis, and Drunella flavilinea) to quantify dietary and dissolved cadmium (Cd) and copper (Cu) bioaccumulation kinetics as a means of characterizing exposure

D. Cain; M. Croteau; S. N. Luoma

2009-01-01

341

The role of bacteria in nutrient recycling in tropical mangrove and other coastal benthic ecosystems  

Microsoft Academic Search

Sedimentary bacteria have generally been recognized as an essential food for protists and invertebrates, forming the base of benthic food webs. This trophic role has been well documented, but bacteria play an equally important role as mineralizers of organic detritus and recyclers of essential nutrients. Recent evidence suggests that this latter role is more important than their trophic function in

Daniel M. Alongi; Townsville MC

1994-01-01

342

A modeling study of benthic detritus flux's impacts on heterotrophic processes in Lake Michigan  

E-print Network

A modeling study of benthic detritus flux's impacts on heterotrophic processes in Lake Michigan food web in Lake Michigan were examined using a three- dimensional (3-D) coupled biological to simulate the heterotrophic process in southern Lake Michigan. INDEX TERMS: 4815 Oceanography: Biological

Chen, Changsheng

343

Structure and function of a benthic invertebrate stream community as influenced by beaver ( Castor canadensis )  

Microsoft Academic Search

Beaver (Castor canadensis) affect the benthic invertebrate community of small woodland streams in Quebec through habitat modifications. Their activities influence community structure through the replacement of lotic taxa by lentic forms and community function by increasing the absolute importance of collectors and predators while decreasing the relative importance of shredders and scrapers in impounded sites. At our study site during

Donald M. McDowell; Robert J. Naiman

1986-01-01

344

ESTIMATING DENSITIES OF ESTUARINE EELGRASS AND BENTHIC MACROALGAE VIA AERIAL PHOTOGRAPHY  

EPA Science Inventory

The goal of this research was to distinguish meadows of native eelgrass (Zostera marina L.) from adjacent beds of benthic green macroalgae in the exposed intertidal zone of Pacific Northwest estuaries, using false-color near-infrared aerial photography. Aerial photographs of Yaq...

345

Using Benthic Marcoinvertebrates Captured by Rock Baskets to Determine Biodiversity in a River.  

NSDL National Science Digital Library

In this ecology investigation, students will build and place rock baskets to collect benthic macroinvertebrates in a local waterway. They will observe and identify their macroinvertebrates and use the data to determine the pollution tolerance index for various areas of a river.

Amanda Meyer

346

The Influence of Coral Reef Benthic Condition on Associated Fish Assemblages  

PubMed Central

Accumulative disturbances can erode a coral reef’s resilience, often leading to replacement of scleractinian corals by macroalgae or other non-coral organisms. These degraded reef systems have been mostly described based on changes in the composition of the reef benthos, and there is little understanding of how such changes are influenced by, and in turn influence, other components of the reef ecosystem. This study investigated the spatial variation in benthic communities on fringing reefs around the inner Seychelles islands. Specifically, relationships between benthic composition and the underlying substrata, as well as the associated fish assemblages were assessed. High variability in benthic composition was found among reefs, with a gradient from high coral cover (up to 58%) and high structural complexity to high macroalgae cover (up to 95%) and low structural complexity at the extremes. This gradient was associated with declining species richness of fishes, reduced diversity of fish functional groups, and lower abundance of corallivorous fishes. There were no reciprocal increases in herbivorous fish abundances, and relationships with other fish functional groups and total fish abundance were weak. Reefs grouping at the extremes of complex coral habitats or low-complexity macroalgal habitats displayed markedly different fish communities, with only two species of benthic invertebrate feeding fishes in greater abundance in the macroalgal habitat. These results have negative implications for the continuation of many coral reef ecosystem processes and services if more reefs shift to extreme degraded conditions dominated by macroalgae. PMID:22870294

Chong-Seng, Karen M.; Mannering, Thomas D.; Pratchett, Morgan S.; Bellwood, David R.; Graham, Nicholas A. J.

2012-01-01

347

Ecology of Lake Whitefish and Response to Changes in Benthic Communities in Lake Huron  

E-print Network

and caloric density, and benthic organisms collected in 2002-2003 were counted and sorted by major taxonomic such as zooplankton, ostracods, chironomids, and Quagga mussels are lower in caloric content than Mysis. Thus, the fish would need to expend more energy foraging than prior to the Mysis decline. In addition

348

Benthic and pelagic food resources for zooplankton in shallow high-latitude lakes and ponds  

E-print Network

Benthic and pelagic food resources for zooplankton in shallow high-latitude lakes and ponds MILLA. 2. In this study we quantified zooplankton food sources and feeding rates in the shallow waters polar desert (Resolute, Nunavut). Five substrate types were tested (beads, bacteria, picophytoplankton

Vincent, Warwick F.

349

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...

350

Longitudinal and Seasonal Distribution of Benthic Invertebrates in the Little Lost River, Idaho  

Microsoft Academic Search

A yearlong investigation of the Little Lost River, Idaho (five sites) was conducted to determine the environmental conditions and benthic invertebrate community composition of the stream and to discover factors responsible for distribution of the benthos. All chemical constituents measured showed a tendency to increase from headwaters to mouth. Stream temperatures ranged from 0-15 C near the headwaters and 0

Douglas A. Andrews; G. Wayne Minshall

1979-01-01

351

Tolerances of five benthic invertebrates to hydrogen ions and metals (Cd, Pb, Al)  

Microsoft Academic Search

96-hr LC50 static bioassays were carried out to determine if the hydrogen ion content and the levels of cadmium, lead, and aluminum characteristic of lakes in the Muskoka District, Ontario, are lethal to benthic macroinvertebrates in four functional groups. The results show that cadmium is the most toxic of the three metals tested to all four functional groups (filter feeders,

G. L. Mackie

1989-01-01

352

The respiration of common benthic invertebrate species from the shallow littoral zone of Lake Esrom, Denmark  

Microsoft Academic Search

To enable estimation of the total assimilation of benthic populations, we measured the oxygen consumption of macroinvertebrates from the littoral zone of a eutrophic lake. The animals were collected all the year round, and their respiration was measured at field temperatures using a closed-bottle method. Multiple regressions relating the rate of oxygen consumption to temperature and body size were established

Kirsten Hamburger; Peter C. Dall

1990-01-01

353

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

E-print Network

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

Patterson, Timothy

354

BENTHIC AND WATER COLUMN PROCESSES IN A SUBTROPICAL ESTUARY: EFFECTS OF LIGHT ON OXYGEN FLUXES  

EPA Science Inventory

Murrell, M.C., J.D. Hagy, J.G. Campbell and J.M. Caffrey. In press. Benthic and Water Column Processes in a Subtropical Estuary: Effects of Light on Oxygen Fluxes (Abstract). To be presented at the ASLO 2004 Summer Meeting: The Changing Landscapes of Oceans and Freshwater, 13-18 ...

355

The benthic invertebrates of the Salton Sea: distribution and seasonal dynamics  

Microsoft Academic Search

The Salton Sea, California's largest inland water body, is an athalassic saline lake with an invertebrate fauna dominated by marine species. The distribution and seasonal dynamics of the benthic macroinvertebrate populations of the Salton Sea were investigated during 1999 in the first survey of the benthos since 1956. Invertebrates were sampled from sediments at depths of 2–12 m, shallow water

P. M. Detwiler; Marie F. Coe; Deborah M. Dexter

2002-01-01

356

Dramatic Shifts in Benthic Microbial Eukaryote Communities following the Deepwater Horizon Oil Spill  

Microsoft Academic Search

Benthic habitats harbour a significant (yet unexplored) diversity of microscopic eukaryote taxa, including metazoan phyla, protists, algae and fungi. These groups are thought to underpin ecosystem functioning across diverse marine environments. Coastal marine habitats in the Gulf of Mexico experienced visible, heavy impacts following the Deepwater Horizon oil spill in 2010, yet our scant knowledge of prior eukaryotic biodiversity has

Holly M. Bik; Kenneth M. Halanych; Jyotsna Sharma; W. Kelley Thomas

2012-01-01

357

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...

358

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...

359

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

E-print Network

Hydrolytic enzyme activity, surfactancy, and dissolved organic matter in the digestive lumens of 19 benthic guts: Enzymes, surfactants and dissolved organic matter by Lawrence M. Mayer', Linda L. Schick', Robert echinoderm and polychaete species were examined, using consistent and quantifiable methods. Enzyme activities

Jumars, Pete

360

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...

361

A Method for Assessing Environmental Risks of Oil-Mineral-Aggregate to Benthic Organisms  

Microsoft Academic Search

Previous studies have shown that Oil-Mineral-Aggregate (OMA) formation enhances the dispersion of marine oil spills, but the potential impacts of settled OMAs on benthic organisms are not well known. A comprehensive numerical approach is proposed here to model the transport of OMAs and assesses their potential risks. The predicted environmental concentrations (PEC) of settled oil in OMAs was calculated using

Haibo Niu; Zhengkai Li; Kenneth Lee; Paul Kepkay; Joseph Mullin

2010-01-01

362

Influence of stability and fragmentation of a worm-reef on benthic macrofauna  

NASA Astrophysics Data System (ADS)

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.

Godet, Laurent; Fournier, Jérôme; Jaffré, Mikaël; Desroy, Nicolas

2011-05-01

363

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

364

SPATIAL PATTERNS AND ECOLOGICAL DETERMINANTS OF BENTHIC ALGAL ASSEMBLAGES IN MID-ATLANTIC STREAMS, USA  

EPA Science Inventory

We attempted to identify spatial patterns and determinants for benthic algal assemblages in Mid-Atlantic streams. Periphyton, water chemistry, stream physical habitat, riparian conditions, and land cover/use in watersheds were characterized at 89 randomly selected stream sites i...

365

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

Microsoft Academic Search

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

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

1996-01-01

366

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

E-print Network

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

Wagner, Diane

367

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

368

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...

369

Paleoecology of benthic metazoans in the Early Cambrian Maotianshan Shale biota and the Middle Cambrian Burgess  

E-print Network

Paleoecology of benthic metazoans in the Early Cambrian Maotianshan Shale biota and the Middle Cambrian Burgess Shale biota: evidence for the Cambrian substrate revolution Stephen Q. Dornbosa,*, David J. Bibliotheks and Informationsystem del Carl von Ossietzky Universitat, Oldenburg, 97­105], and the impact

Dornbos, Stephen Q.

370

Benthic macroinvertebrate associations in relation to environmental factors in Georgian Bay  

Microsoft Academic Search

Association analysis of data on benthic macroinvertebrates in 257 samples from Georgian Bay, followed by discriminant analysis of water and sediment characteristics, facilitated a quantitative description of trophic variability within a relatively unpolluted system. Discriminating variables were bottom water temperature, water pH and Ca, sediment organic matter, sand, silt, clay, total P, Zn, Pb, and Hg. Four discriminating functions, accounting

M. G. Johnson; O. C. McNeil; S. E. George

1987-01-01

371

Benthic diatom composition in isolated forested wetlands subject to drying: implications for monitoring and assessment  

EPA Science Inventory

The development of bioindicators for wetlands, especially ephemerally hydrated depressional and isolated wetlands, can be problematic because of seasonal hydrology and target organism biology. To determine if benthic diatoms could be used as a year-round biological indicator of w...

372

Benthic diatom composition in wet and dry isolated forested wetlands: implications for monitoring and assessment  

EPA Science Inventory

The development of bioindicators for wetlands, especially ephemerally hydrated depressional and isolated wetlands, can be problematic because of seasonal changes in hydrology and target organism biology. To determine if benthic diatoms could be used as a year-round biological ind...

373

Enrichment of aquaculture earthen ponds with Hediste diversicolor: Consequences for benthic dynamics and natural productivity  

Microsoft Academic Search

The present work analysed the potential impacts of the enrichment of semi-intensive production earthen ponds with the ragworm Hediste diversicolor in the benthic dynamics and natural productivity. The macrobenthos and sediment characteristics were analysed in two enriched ponds and two control ponds in May, June and September 2005. The number of species, Margalef species richness and biomass (AFDW) were generally

Susana Carvalho; Marisa Barata; Miguel B. Gaspar; Pedro Pousão-Ferreira; Luís Cancela da Fonseca

2007-01-01

374

Protein synthesis in a solitary benthic cephalopod, the Southern dumpling squid (Euprymna tasmanica)  

E-print Network

Protein synthesis in a solitary benthic cephalopod, the Southern dumpling squid (Euprymna tasmanica-history Protein synthesis Squid Tissue protein synthesis Rates of protein synthesis were measured in the whole-dose of 3 H phenylalanine for the measurement of protein synthesis with different size squid and to make

McFall-Ngai, Margaret

375

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

Microsoft Academic Search

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

Mikio Inoue; Masanobu Miyayoshi; Shin Sone

2005-01-01

376

Benthic foraminiferal dissolved-oxygen index and dissolved-oxygen levels in the modern ocean  

Microsoft Academic Search

Changes in oxygen concentrations at the sediment-water interface play a major role in controlling benthic foraminiferal assemblages and morphologic characteristics; such changes are reflected in size, wall thickness, porosity, and also taxa (genera and species) of foraminifera present. These morphologic and taxonomic differences have been quantified as a dissolved-oxygen index. This paper demonstrates that the foraminiferal oxygen index derived from

Kunio Kaiho

1994-01-01

377

Biomonitoring through biological traits of benthic macroinvertebrates: how to use species trait databases?  

Microsoft Academic Search

The aim of this paper was to investigate the potential use of biological and ecological traits of macroinvertebrates as indicator systems of quality conditions in freshwater ecosystems. To provide a framework for the trait analysis, a data base was developed; it stored biological information about 472 benthic macroinvertebrate taxa. Twenty-two variables describing biological and ecological traits were resolved into a

Philippe Usseglio-Polatera; Michel Bournaud; Philippe Richoux; Henri Tachet

2000-01-01

378

Streamflow characteristics and benthic invertebrate assemblages in streams across the western United States  

USGS Publications Warehouse

Hydrographic characteristics of streamflow, such as high-flow pulses, base flow (background discharge between floods), extreme low flows, and floods, significantly influence aquatic organisms. Streamflow can be described in terms of magnitude, timing, duration, frequency, and variation (hydrologic regime). These characteristics have broad effects on ecosystem productivity, habitat structure, and ultimately on resident fish, invertebrate, and algae communities. Increasing human use of limited water resources has modified hydrologic regimes worldwide. Identifying the most ecologically significant hydrographic characteristics would facilitate the development of water-management strategies. Benthic invertebrates include insects, mollusks (snails and clams), worms, and crustaceans (shrimp) that live on the streambed. Invertebrates play an important role in the food web, consuming other invertebrates and algae and being consumed by fish and birds. Hydrologic alteration associated with land and water use can change the natural hydrologic regime and may affect benthic invertebrate assemblage composition and structure through changes in density of invertebrates or taxa richness (number of different species). This study examined associations between the hydrologic regime and characteristics of benthic invertebrate assemblages across the western United States and developed tools to identify streamflow characteristics that are likely to affect benthic invertebrate assemblages.

Brasher, Anne M.D.; Konrad, Chris P.; May, Jason T.; Edmiston, C. Scott; Close, Rebecca N.

2010-01-01

379

Sediment reworking by marine benthic species from the Gullmar Fjord (Western Sweden): Importance of faunal biovolume  

E-print Network

Sediment reworking by marine benthic species from the Gullmar Fjord (Western Sweden): Importance, France b Department of Chemistry, Göteborg University, SE-412 96 Göteborg, Sweden c Paléoenvironnements Research Station, SE-450 34 Fiskebäckskil, Sweden f Laboratoire d'Ecologie Fonctionnelle (UMR 5245-CNRS

Poggiale, Jean-Christophe

380

Benthic interface studies with landers. Consideration of lander\\/interface interactions and their design implications  

Microsoft Academic Search

The physical and chemical properties and behaviour of the benthic interface cannot generally be predicted from first principles so must be determined empirically. The physical characteristics of the interface are such that in situ determinations provide the most realistic parameter values and at time and space scales, which describe the full heterogeneity of the interfacial environment. This is especially the

W. R. Parker; K. Doyle; E. R. Parker; P. J. Kershaw; S. J. Malcolm; P. Lomas

2003-01-01

381

Effects of Suction-Dredge Gold Mining on Benthic Invertebrates in a Northern California Stream  

Microsoft Academic Search

The effects on benthic invertebrates of mining with two suction dredges were investigated in 1983 by using artificial-substrate samplers in Big East Fork Creek, a tributary to Canyon Creek in northern California. The samplers were placed in Big East Fork Creek above and below the dredge site and in Canyon Creek above and below the confluence of Big East Fork

William L. Somer; Thomas J. Hassler

1992-01-01

382

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

Microsoft Academic Search

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

Fay Woodruff; Samuel M. Savin; Linda Abel

383

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...

384

Living benthic foraminifers from the central Arctic Ocean: faunal composition, standing stock and diversity  

Microsoft Academic Search

Fifty short sediment cores collected with a multiple corer and five box cores from the central Arctic Ocean were analysed to study the ecology and distribution of benthic foraminifers. To work out living faunal associations, standing stock and diversity, separate analyses of living (Rose Bengal stained) and dead foraminifers were carried out for the sediment surface. The size fractions between

Jutta E. Wollenburg; Andreas Mackensen

1998-01-01

385

Photo: TH DeWitt, USEPA EPA's benthic habitat data for Yaquina estuary  

E-print Network

Photo: TH DeWitt, USEPA EPA's benthic habitat data for Yaquina estuary Presented by Ted DeWitt Data & channel whole estuary or lower & mid estuary Bathymetry + topography 1998, 1999, 2000, 2002 various intertidal & subtidal whole estuary Wind-wave exposure (modelled) 2000? ? Intertidal whole estuary Intertidal

Wright, Dawn Jeannine

386

OPTIMUM BENTHIC MACROFAUNAL SAMPLING PROTOCOL FOR DETECTING DIFFERENCES BETWEEN FOUR HABITATS IN WILLAPA BAY, WASHINGTON, USA  

EPA Science Inventory

Abstract -- As part of an effort to estimate estuarine habitat values with respect to ecological indicators of benthic macrofaunal community condition, an optimal (effective and least costly) sampling protocol (sample unit size [area 3 depth], sieve mesh size, and sample number [...

387

Chlorinated organic contaminants in benthic organisms of the lower Fraser River near Agassiz, British Columbia  

E-print Network

1 Chlorinated organic contaminants in benthic organisms of the lower Fraser River near Agassiz published as a peer-reviewed article: Richardson, J.S. and C.D. Levings. 1996. Chlorinated organic Columbia in winter 1993 to assess concentrations of chlorinated organic contaminants. Concentrations

388

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...

389

MEDITERRANEAN CLIMATE STREAMS Review Paper Long-term population and community patterns of benthic  

E-print Network

and develop generalities that may apply broadly to med-climate streams worldwide. Severe drought may result to reduce influence of interannual variability on impact detection. Long-term data can be used to develop of benthic macroinvertebrates and fishes in streams have been conducted informally as part of human survival

Carlson, Stephanie

390

Impacts of ocean acidification on large benthic foraminifers: Results from laboratory experiments  

Microsoft Academic Search

Ocean acidification has become recognized recently to be a major threat to calcifying organisms. Previous studies have reported that calcification rates of calcareous marine organisms (e.g., corals, foraminifers, coccolithophores, pteropods, mussels, and oysters) change in response to lowering pH levels even in waters oversaturated with respect to calcium carbonate. However, the impact of ocean acidification on large benthic foraminifers, which

Azumi Kuroyanagi; Hodaka Kawahata; Atsushi Suzuki; Kazuhiko Fujita; Takahiro Irie

2009-01-01

391

COMMUNITY ECOLOGY -ORIGINAL PAPER The effects of topdown versus bottomup control on benthic  

E-print Network

and associated increases in sea surface temperature and ocean acidification, are among the most important global be an effective strategy for restoring ecosystem structure and function and in reversing coral­ algal phaseCOMMUNITY ECOLOGY - ORIGINAL PAPER The effects of top­down versus bottom­up control on benthic

Smith, Jennifer E.

392

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

Microsoft Academic Search

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

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

2006-01-01

393

Importance of benthic production to fish populations in Lake Mead prior to the establishment of quagga mussels  

USGS Publications Warehouse

Limnologists recently have developed an interest in quantifying benthic resource contributions to higher-level consumers. Much of this research focuses on natural lakes with very little research in reservoirs. In this study, we provide a contemporary snapshot of the food web structure of Lake Mead to evaluate the contribution of benthic resources to fish consumers. In addition, we document the available food to fishes on soft sediments and changes to the invertebrate community over 2 time periods. Benthic invertebrate food availability for fishes is greater in Las Vegas Bay than Overton Arm. Las Vegas Bay is dominated by oligochaetes, whose biomass increased with depth, while Overton Arm is dominated by chironomids, whose biomass did not change with depth. Diet and isotopic measurements indicate the fish community largely relies on benthic resources regardless of basin (Las Vegas Bay >80%; Overton Arm >92%); however, the threadfin shad likely contribute more to largemouth and striped bass production in Overton Arm versus Las Vegas Bay. A 2-time period analysis, pre and post quagga mussel establishment and during lake level declines, suggests there is no change in the density of benthic invertebrates in Boulder Basin, but there were greater abundances of select taxa in this basin by season and depth than in other basins. Given the potential of alterations as a result of the expansion of quagga mussel and the reliance of the fishery on benthic resources, future investigation of basin specific, benthic processes is recommended.

Umek, John; Chandra, Sudeep; Rosen, Michael; Wittmann, Marion; Sullivan, Joe; Orsak, Erik

2010-01-01

394

Food sources of benthic animals on intertidal and subtidal bottoms in inner Ariake Sound, southern Japan, determined by stable isotopes  

NASA Astrophysics Data System (ADS)

To evaluate the relative importance of possible food sources, including riverine particulate organic matter, reeds, benthic microalgae, seaweeds, cultured laver ( Porphyra) and coastal phytoplankton, for commercial bivalves and co-occurring benthic animals, 73 macrofaunal species were collected from intertidal and subtidal soft bottoms in the inner part of Ariake Sound, Kyushu, southern Japan, and their isotopic compositions were analyzed. The results revealed that (1) both intertidal and subtidal food webs were constituted of 3 trophic levels, (2) suspension-feeding bivalves utilize a mixture of benthic microalgae and coastal phytoplankton, and omnivores and carnivores incorporate benthic microalgae and phytoplankton through their intermediate prey, and (3) 3 bivalves ( Scapharca kagoshimensis, Modiolus metcalfei and Atrina lischkeana) inhabiting both intertidal and subtidal bottoms showed similar seasonal fluctuations, suggesting no difference in the diet composition among the species and between the 2 habitats. We conclude that a large biomass of benthic microalgae which was approximately equal to that of phytoplankton and the strong tidal currents that would resuspend benthic microalgae and transport them to subtidal bottom areas account for the benthic microalgal and phytoplankton based trophic structure in the inner part of Ariake Sound.

Yokoyama, Hisashi; Sakami, Tomoko; Ishihi, Yuka

2009-04-01

395

Comparison of Adjective vs. Benthic Sources of Nutrients to a Former Salt Pond under Restoration  

NASA Astrophysics Data System (ADS)

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.

Topping, B.; Kuwabara, J. S.; Garrett, K.; Takekawa, J.; Piotter, S.; Parchaso, F.

2013-12-01

396

Lava Layering  

NSDL National Science Digital Library

This is a lesson about geologic history. Learners will work together to create models of volcanic lava flows and analyze the layers that form on a planet's surface. They will sequence lava flows produced by multiple eruptions. Students will be asked to observe where the flows travel, make a model, and interpret the stratigraphy. Students will use their volcanic layering model to demonstrate the relative dating and geologic mapping principles to later be applied to satellite imagery. The lesson models scientific inquiry using the 5E instructional model and includes teacher notes and vocabulary.

397

Effects of Benthic Flux on Dissolved-Mercury Distributions in Camp Far West Reservoir, California  

NASA Astrophysics Data System (ADS)

Benthic flux measurements of dissolved mercury species were made on sediment cores from Camp Far West Reservoir, a reservoir in which elevated mercury levels in sport fish had previously been documented. The reservoir is located downstream of historic hydraulic placer-gold mining and ore processing activities in the Bear River watershed of the northern Sierra Nevada. Field and laboratory studies were conducted in April and November of 2002 (one of the driest years on record for the area) to provide the first direct measurements of the benthic flux of dissolved mercury species between bottom sediment and the water column at three locations within the reservoir. Ancillary data, including nutrient and ligand fluxes, and benthic biological characterizations, were also gathered to provide a water-quality framework with which to interpret the mercury results. The following are the major observations made from interdependent physical, biological, and chemical data. Bottom water total mercury (HgT) concentrations ranged from 2.94 to 18.3 pM. Dissolved HgT benthic fluxes were generally higher in April than in November 2002 (based on site averages from replicate cores). HgT fluxes of 36.3 and -28.4 pmoles-m-2-h-1 were measured in cores from the deep site which was suboxic in November, contrasting with positive fluxes of 306 and 272 pmoles-m-2-h-1 at that site in April 2002 when the bottom water was oxic. All six measurements of HgT flux in April 2002 and five of six in November 2002 resulted in positive values (i.e., out of the sediment into the overlying water column). Consistent with benthic fluxes for HgT, dissolved MeHg fluxes were: (a) generally positive in April 2002, (b) negligible at all sites in November 2002, and (c) at least two orders of magnitude lower than total-mercury fluxes, roughly consistent with concentration differences between species. Observed concentration ranges for MeHg in bottom water ranged from less than the detection limit (0.20 pM) at the two shallower, up-gradient sites to 0.48 +/- 0.03 pM (n=3) at the deepest sampling site in November 2002. Dissolved MeHg concentrations in the bottom waters were significantly lower under the low-flow conditions of November 2002 relative to high flow in April 2002, but spatial trends were not temporally consistent. The reservoir was highly phosphate-limited with molar N:P ratios in water column samples ranging from 136 to >5,000 (compared to the Redfield N:P molar ratio of 16). Sulfide benthic fluxes were highest (1,180 +/- 50 nmoles-m-2-h-1) at the deepest site in November 2002 following at least 2 weeks of hypolimnetic anoxia (based on prior water-column monitoring), and lowest at the same site in April 2002 (290 +/- 30 nmoles-m-2-h-1) under oxic, high-flow conditions. Sparse benthic macroinvertebrate distributions, mirrored by low benthic-chlorophyll concentrations, were considered to be inconsequential factors mediating benthic flux. Despite their seasonal variability, the magnitude of benthic flux estimates for HgT were consistently comparable to or greater than riverine sources during a relatively dry year. Diffusive transport of dissolved, bioavailable mercury species between the reservoir bed and water column may therefore be an important process regulating the concentration of mercury species in the reservoir water column.

Kuwabara, J. S.; Alpers, C. N.; Marvin-Dipasquale, M.; Topping, B. R.; Carter, J. L.; Stewart, A. R.; Fend, S. V.; Parchaso, F.; Moon, G. E.; Krabbenhoft, D. P.; Agee, J. L.; Kieu, L. H.

2003-12-01

398

Transport Layer Cornell University  

E-print Network

Transport Layer Ao Tang Cornell University Ithaca, NY 14853 Lachlan L. H. Andrew California is called a "layer". One of the layering structures often used is the five-layer model consisting of the physical layer, the link layer, the network layer, the transport layer and the application layer1 . See

Andrew, Lachlan

399

Effects of heavy metals pollution on benthic foraminifera assemblage: the Gulf of Gabes, Tunisia  

NASA Astrophysics Data System (ADS)

Benthic foraminifera are amongst the most abundant protists found in huge marine and brackish water habitat. During the last few decades, many researches had been focused on using benthic foraminifera as bioindicators of marine pollution caused by industrial, domestic and agricultural waste, oil or heavy metal contamination. The aim of this research is to investigate heavy metals pollution in superficial sediments in two industrial locations at the Gulf of Gabes and to examine the reaction of benthic foraminifera towards metallic concentration. The Gulf of Gabes, located on the eastern coast of Tunisia, is regarded as an extremely vital zone and considered as one of the most important area for fishing in the country. During last years, the coastal area of this region had known an important demographic and industrial development, leading to the presence of uncontrolled discharge. Fifteen superficial sediment samples were collected along the coastline of Skhira and Ghannouch- Gabes. They have been analyzed for Al, Cd, Cr, Cu, Pb, and Zn concentrations as well as for the species composition of benthic foraminifera. Results show three levels of metallic contamination with high concentration of cadmium and zinc. Thirty five benthic foraminifera species were identified. Ammonia parkinsoniana, Ammonia beccarii, Peneroplis planatus, Triloculina trigonula and Adelosina longirostraare are the most abundant and common species. Increasing pollution results in a lower species diversity as well as population density, with the presence of a barren zone, and more frequent abnormal specimens. A complementary statistical analysis (PCA/FA and matrix correlation) shows that heavy metals are resulting from the same anthropogenic source and negative correlation between faunal parameters (density and diversity) and pollutants concentrations.

Ayadi, Najla; Zghal, Ihsen; Bouzid, Jalel; Abdennaceur Ouali, Jamel

2014-05-01

400

Oxygenation episodes on the continental shelf of central Peru: Remote forcing and benthic ecosystem response  

NASA Astrophysics Data System (ADS)

The interplay between the oxygen minimum zone and remotely-forced oxygenation episodes determines the fate of the benthic subsystem off the Central Peruvian coast. We analyzed a 12 year monthly time-series of oceanographic and benthic parameters at 94 m depth off Callao, Central Peru (12°S), to analyze: (i) near-bottom oxygen level on the continental shelf in relation to dynamic height on the equator (095°W); and (ii) benthic ecosystem responses to oxygen change (macrobiotic infauna, meiofauna, and sulphide-oxidizing bacteria, Thioploca spp.). Shelf oxygenation episodes occurred after equatorial dynamic height increases one month before, consistent with the propagation of coastal trapped waves. Several but not all of these episodes occurred during El Niños. The benthic biota responded to oxygenation episodes by undergoing succession through three major ecological states. Under strong oxygen deficiency or anoxia, the sediments were nearly defaunated of macro-invertebrates and Thioploca was scarce, such that nematode biomass dominated the macro- and meiobiotas. When frequency of oxygenation events reduced the periods of anoxia, but the prevailing oxygen range was 10-20 ?mol L -1, mats of Thioploca formed and dominated the biomass. Finally, with frequent and intense (>40 ?mol L -1) oxygenation, the sediments were colonized by macrofauna, which then dominated biomass. The Thioploca state evolved during the 2002-2003 weak EN, while the macrofauna state was developed during the onset of the strong1997-1998 EN. Repeated episodes of strong oxygen deficiency during the summer of 2004, in parallel with the occurrence of red tides in surface waters, resulted in the collapse of Thioploca mats and development of the Nematode state. Ecological interactions may affect persistence or the transition between benthic ecosystem states.

Gutiérrez, Dimitri; Enríquez, E.; Purca, S.; Quipúzcoa, L.; Marquina, R.; Flores, G.; Graco, M.

2008-10-01

401

Implications of Colorado river (Texas, USA) freshwater inflow to benthic ecosystem dynamics: A modeling study  

NASA Astrophysics Data System (ADS)

Estuaries are defined by mixing of freshwater from rivers and saltwater from seas. Water resource development can reduce river flows to the coast, but it is difficult to predict effects on estuaries. The Lavaca-Colorado Estuary is a major estuarine system along the Texas coast that provides major economic benefit to the region by supporting a variety of agricultural, residential, industrial, and recreational functions. New water projects could divert freshwater from Matagorda Bay. So, what environmental effects could result from further changes to inflow patterns in the Matagorda Bay system? To answer this question, a bioenergetic model, calibrated using a long-term dataset of benthic biomass, was run to investigate dynamics of macrobenthic biomass related to salinity regimes in the estuary. The model simulation results were interpreted to assess the role of freshwater inflow in controlling benthic productivity. Simulations, based on calibrated parameters (1988-1999), were run for a long-term period from 1988 to 2005. The model performance was found to be promising with the best percent root mean square (RMS) difference being 63% and worst being 92%. Sensitivity tests for the benthic responses to changes in salinity show that, in general, when salinity increased with decreasing nutrient concentrations, deposit feeder biomass increased while suspension feeder biomass decreased. Estuary-wide comparison predicts that reducing freshwater inflow may cause the upper and lower bay communities to respond in different ways. Reduced inflow to Lavaca Bay would result in decreasing benthic biomass; whereas, in Matagorda Bay, biomass would increase. Also, functional diversity would decrease in both bays with decreasing inflow. These effects are probably due to the benthic community acclimating to different salinity regimes, or more (or less) salt tolerant species populating the area. It is concluded that freshwater inflow plays an important role in maintaining the observed character of estuarine productivity through the combined effects of the frequency, duration, timing, and magnitude of inflow, particularly during droughts or low-flow periods.

Kim, Hae-Cheol; Montagna, Paul A.

2009-08-01

402

Benthic-Pelagic Coupling: Effects on Nematode Communities along Southern European Continental Margins  

PubMed Central

Along a west-to-east axis spanning the Galicia Bank region (Iberian margin) and the Mediterranean basin, a reduction in surface primary productivity and in seafloor flux of particulate organic carbon was mirrored in the in situ organic matter quantity and quality within the underlying deep-sea sediments at different water depths (1200, 1900 and 3000 m). Nematode standing stock (abundance and biomass) and genus and trophic composition were investigated to evaluate downward benthic-pelagic coupling. The longitudinal decline in seafloor particulate organic carbon flux was reflected by a reduction in benthic phytopigment concentrations and nematode standing stock. An exception was the station sampled at the Galicia Bank seamount, where despite the maximal particulate organic carbon flux estimate, we observed reduced pigment levels and nematode standing stock. The strong hydrodynamic forcing at this station was believed to be the main cause of the local decoupling between pelagic and benthic processes. Besides a longitudinal cline in nematode standing stock, we noticed a west-to-east gradient in nematode genus and feeding type composition (owing to an increasing importance of predatory/scavenging nematodes with longitude) governed by potential proxies for food availability (percentage of nitrogen, organic carbon, and total organic matter). Within-station variability in generic composition was elevated in sediments with lower phytopigment concentrations. Standing stock appeared to be regulated by sedimentation rates and benthic environmental variables, whereas genus composition covaried only with benthic environmental variables. The coupling between deep-sea nematode assemblages and surface water processes evidenced in the present study suggests that it is likely that climate change will affect the composition and function of deep-sea nematodes. PMID:23565176

Pape, Ellen; Jones, Daniel O. B.; Manini, Elena; Bezerra, Tania Nara; Vanreusel, Ann

2013-01-01

403

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

PubMed Central

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

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

2013-01-01

404

Layered Liquids  

NSDL National Science Digital Library

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

Eichinger, John

2009-05-30

405

Leaky Layers  

NSDL National Science Digital Library

Figure from the Nature Geoscience article, Geodynamics: Layer cake or plum pudding? by Paul Tackley (Nature Geoscience 1, 157 - 158 (2008)). The figure shows the current understanding of the interaction between the 660 km discontinuity, the core-mantle boundary, downgoing slabs, upwelling plumes.

Tackley, Paul J.; Geoscience, Nature

406

Structures of benthic prokaryotic communities and their hydrolytic enzyme activities resuspended from samples of intertidal mudflats: An experimental approach  

NASA Astrophysics Data System (ADS)

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.

Mallet, Clarisse; Agogué, Hélène; Bonnemoy, Frédérique; Guizien, Katell; Orvain, Francis; Dupuy, Christine

2014-09-01

407

Experimental evidence of biomineralisation for three benthic foraminiferal species under different redox conditions: implications for paleo-redox proxies interpretation  

NASA Astrophysics Data System (ADS)

Foraminifera are among the most used group of organisms for paleoceanographic and paleoenvironmental reconstructions thanks to their ability to fossilize and the preservation potential in marine sediments. Calibrations of foraminiferal-based proxies are therefore of crucial importance for precise reconstructions together with uncertainty estimates of paleoenvironments; experimental approaches are increasingly used to deepen the understanding of biological and ecological aspects of biomineralization that can influence shell geochemistry. Some of the most important and still unanswered questions are: under which circumstances can foraminiferal biomineralization take place? Can their shells record different oxygenation levels and redox fronts migrations at the sediment-water interface? The hypothesis of their ability to biomineralise even in absence of oxygen was investigated in an experimental study. Calcein-labeled specimens of three benthic foraminiferal species, Ammonia tepida, Bulimina marginata and Cassidulina laevigata were introduced in different sediment layers of reconstituted cores (up to 10 cm depth). The sediment layers were separated by 100 µm mesh-size nets preventing specimen migrations. We could therefore evaluate the ability of the species to calcify at different redox fronts in the sediment. The results show that all species were able to calcify within 2 months in hypoxic. Two of them (Ammonia tepida and Bulimina marginata) are also able to calcify in completely anoxic conditions. The result suggests that foraminifera could register in their calcareous shells the migration of redox fronts associated to bottom-water oxygen depletions and anoxic events. With the help of microanalytical tools it will potentially be possible to reconstruct past oxygen levels with much higher accuracy and precision and to obtain proxies of completely anoxic conditions.

Nardelli, Maria Pia; Barras, Christine; Metzger, Edouard; Filipsson, Helena; Jorissen, Frans; Geslin, Emmanuelle

2014-05-01

408

Lava Layering  

NSDL National Science Digital Library

The Planetary Geology Group at Arizona State University developed this online activity to teach elementary and middle school students "the stratigraphy (layers) of lava flows produced by multiple eruptions" on the moon. The first part of the website provides teachers with background information about the layers of basaltic lava flows that cover about sixteen percent of the Moon as well as how to prepare for the activity and what to expect. Visitors can use the second part of the website as an instruction sheet for the students. The website describes how users can examine the patterns of lava flows on the moon with the help of four simple ingredients: baking soda, vinegar, food coloring, and paper cups. The questions provided at the end will help students understand the process that is taking place in their experiments.

409

Linking the toxic metals to benthic community alteration: a case study of ecological status in the Bohai Bay.  

PubMed

Ecological effects and quality status of sediments in the Bohai Bay (North China) were studied by incorporating the traditional chemical analysis and benthic community structure. In the present study, paired sediments from 20 stations were sampled for chemical analysis and benthic assemblages. The overall results demonstrated that sediment impairment mainly appeared in the southern part of the Bay. The results obtained from the principal component analysis regarding benthic data and potential explanatory factors indicated that As, Hg and petroleum hydrocarbons (PHs) were responsible for the distribution of macrofaunal assemblages. Canonical correspondence analysis further showed As was significantly correlated to the benthic alteration, which provided evidence of ecological relevance to chemical substances of concern. Overall, this study revealed the metal contamination in the Bohai Bay was not as severe as previously regarded. Yet, further investigation is still needed considering the complexity of sediment matrices. PMID:24768175

Wu, Bin; Song, Jinming; Li, Xuegang

2014-06-15

410

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

E-print Network

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 ...

Tapia, Fabián

2005-01-01

411

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...

412

Estimating benthic secondary production from aquatic insect emergence in streams affected by mountaintop removal coal mining, West Virginia USA  

EPA Science Inventory

Mountaintop removal and valley fill (MTR/VF) coal mining recountours the Appalachian landscape, buries headwater stream channels, and degrades downstream water quality. The goal of this study was to compare benthic community production estimates, based on seasonal insect emergen...

413

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

E-print Network

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) ...

Filipsson, H. L.

414

Comparison of marine productivity among Outer Continental Shelf planning areas. Supplement: An evaluation of benthic habitat primary productivity. Final report  

SciTech Connect

Literature on current primary productivity was reviewed and evaluated for each of nine benthic communities or habitats, estimates of daily and annual benthic primary productivity were derived within each community, the benthic primary estimates were related to an estimate of areal extent of each community within or adjacent to each OCS planning area. Direct comparisons between habitats was difficult because of the varying measures and methodologies used. Coastal marshes were the most prevalent habitat type evaluated. Mangrove and coral reef habitats were highly productive but occur within few planning areas. Benthic diatoms and blue-green algae are less productive in terms of estimated annual productivity on a per square meter basis; these habitats have the potential to occur across wide areas of the OCS and should not be overlooked.

Balcom, B.J.; Foster, M.A.; Fourqurean, J.J.; Heine, J.N.; Leonard, G.H.

1991-01-01

415

Prepared in cooperation with the U.S. Fish and Wildlife Service Benthic Oxygen Demand in Three Former  

E-print Network

:...................................................................................................................................3 Dissolved-Oxygen Flux Estimates Based on Diffusion .............................................................................................................................6 Dissolved Oxygen (DOPrepared in cooperation with the U.S. Fish and Wildlife Service Benthic Oxygen Demand in Three

416

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 ...

417

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

NASA Astrophysics Data System (ADS)

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.

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

418

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

NASA Astrophysics Data System (ADS)

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.

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

2011-11-01

419

Food web flows through a sub-arctic deep-sea benthic community  

NASA Astrophysics Data System (ADS)

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.

Gontikaki, E.; van Oevelen, D.; Soetaert, K.; Witte, U.

2011-11-01

420

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

NASA Astrophysics Data System (ADS)

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.

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

2014-10-01

421

Data report: Oligocene paleoceanography of the equatorial Pacific Ocean: planktonic and benthic stable isotope results from Site 1218  

E-print Network

Wilson, P.A., Lyle, M., and Firth, J.V. (Eds.) Proceedings of the Ocean Drilling Program, Scientific Results Volume 199 DATA REPORT: OLIGOCENE PALEOCEANOGRAPHY OF THE EQUATORIAL PACIFIC OCEAN: PLANKTONIC AND BENTHIC FORAMINIFER STABLE ISOTOPE... RESULTS FROM SITE 1218 1 Bridget S. Wade 2,3 and Heiko P?like 4,5 ABSTRACT To document the evolution of the early cryosphere, stable isotope analyses were conducted on the planktonic and benthic foraminifers from Ocean Drilling Program Site 1218. We...

Wade, Bridget S.; P??like, Heiko

2005-01-01

422

Benthic community indicators over a long period of monitoring (2000-2012) of the Saronikos Gulf, Greece, Eastern Mediterranean.  

PubMed

An analysis of the results of the 12-year regular monitoring (2000-2012) of benthic communities in Saronikos Gulf and Elefsis Bay (Eastern Mediterranean, Greece) in relation to the functioning of the Psittalia Wastewater Treatment Plant (WWTP) and advances in treatment is presented. Benthic community indicators applied include the Bentix index adopted for the implementation of the Water Framework Directive (WFD); the diversity and species richness proposed in combination with the Bentix index for the evaluation of certain attributes of the Sea-floor Integrity descriptor for the marine waters of Greece, under the Marine Strategy Framework Directive (MSFD), and the evenness index. The benthic and environmental data were treated according to the distance from the outfall, largely accounting for the variance of the indicators, to investigate trends along the monitoring. Results showed an upgrade of the condition of the benthic communities of Saronikos Gulf throughout the monitoring period mostly demonstrated by the Bentix and diversity indices. A change in the trends of most indices was especially evident after 2004, especially in the areas more adjacent to the outfall zones, when the advanced secondary biological treatment plant was completed and commissioned. Sediment parameters' trend patterns indicate a delayed reaction to recovery processes in relation to benthic indices. An evaluation of the current status of the benthic communities based on the indices applied showed a gradient from a moderate ecological status at stations up to a distance of 8,000 m from the outfalls to good environmental and ecological status at more remote stations. At shallower stations located at a distance of more than 4,000 m from the outfall, benthic communities also present good environmental status. In Elefsis Bay, the enclosed physiography, shallower depth and local pressures result in more adverse environmental conditions for benthic communities and a more complex influence from WWTP advances. PMID:24522712

Simboura, N; Zenetos, A; Pancucci-Papadopoulou, M A

2014-06-01

423

Benthic community respiration in the N.W. Atlantic Ocean: in situ measurements from 40 to 5200 m  

Microsoft Academic Search

Benthic community respiration was measured in situ at 9 stations along the Gay Head-Bermuda transect from depths of 40 to 5200 m. Three methods were used; bell jar respirometers, grab respirometers, and free vehicle respirometers. Benthic community respiration rates spanned three orders of magnitude, decreasing from 21.5 ml O2 m-2 h-1 at 40 m in November to 0.02 ml O2

K. L. Smith

1978-01-01

424

Pelagic-benthic coupling within an upwelling system of the subtropical northeast Atlantic over the last 35 ka BP  

NASA Astrophysics Data System (ADS)

We present a high resolution, multiproxy study of the relationship between pelagic and benthic environments of a coastal upwelling system in the subtropical NE Atlantic Ocean. Marine sediments corresponding to late MIS3 to the Holocene in the radiocarbon dated core GeoB7926, retrieved off Mauritania (21°N) were analysed to reconstruct productivity in surface waters and its linkage to deep waters during the last 35 ka BP. High latitude cold events and changes in atmospheric and oceanographic dynamics influenced upwelling intensity over this time period. Subsequently, this caused changes in primary productivity off this low-latitude coastal upwelling locality. The benthic foraminiferal fauna displays four main community shifts corresponding to fundamental climatic events, first of all during late MIS3 (35-28 ka BP), secondly from 28 to 19 ka BP (including Heinrich event 2 and the LGM), thirdly within Heinrich event 1, the Bølling Allerød and the Younger Dryas (18-11.5 ka BP) and finally during the Holocene (11.5-0 ka BP). In particular, strong pelagic-benthic coupling is apparent in MIS 3, as demonstrated by increased primary productivity, indicated by moderate DAR and the dominance of benthic foraminiferal species which prefer fresh phytodetritus. A decline in upwelling intensity and nutrient availability follows, which resulted in a proportionately larger amount of older, degraded matter, provoking a shift in the benthic foraminifera fauna composition. This rapid response of the benthic environment continues with a progressive increase in upwelling intensity due to sea level and oceanographic changes and according high surface production during the LGM. During Heinrich event 1 and the Younger Dryas, extreme levels of primary production actually hindered benthic environment through the development of low oxygen conditions. After this period, a final change in benthic foraminiferal community composition occurs which indicates a return to more oxygenated conditions during the Holocene.

McKay, C. L.; Filipsson, H. L.; Romero, O. E.; Stuut, J.-B. W.; Donner, B.

2014-12-01

425

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

USGS Publications Warehouse

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.

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

2014-01-01

426

Calibration and evaluation of five indicators of benthic community condition in two California bay and estuary habitats.  

PubMed

Many types of indices have been developed to assess benthic invertebrate community condition, but there have been few studies evaluating the relative performance of different index approaches. Here we calibrate and compare the performance of five indices: the Benthic Response Index (BRI), Benthic Quality Index (BQI), Relative Benthic Index (RBI), River Invertebrate Prediction and Classification System (RIVPACS), and the Index of Biotic Integrity (IBI). We also examine whether index performance improves when the different indices, which rely on measurement of different properties, are used in combination. The five indices were calibrated for two geographies using 238 samples from southern California marine bays and 125 samples from polyhaline San Francisco Bay. Index performance was evaluated by comparing index assessments of 35 sites to the best professional judgment of nine benthic experts. None of the individual indices performed as well as the average expert in ranking sample condition or evaluating whether benthic assemblages exhibited evidence of disturbance. However, several index combinations outperformed the average expert. When results from both habitats were combined, two four-index combinations and a three-index combination performed best. However, performance differences among several combinations were small enough that factors such as logistics can also become a consideration in index selection. PMID:19136123

Ranasinghe, J Ananda; Weisberg, Stephen B; Smith, Robert W; Montagne, David E; Thompson, Bruce; Oakden, James M; Huff, David D; Cadien, Donald B; Velarde, Ronald G; Ritter, Kerry J

2009-01-01

427

Changes in Benthic Macroinvertebrate Communities in Relation to Water Chemistry in 17 Lakes in South-Central Ontario, Canada  

NASA Astrophysics Data System (ADS)

Benthic macroinvertebrates can be strong indicators of lake conditions, integrating the effects of all physical and chemical aspects of the environment. In lake systems that have been exposed to acid deposition, benthic community structure may be impacted by changes in water chemistry associated with either acidification or subsequent recovery. Multivariate analysis was used to examine temporal changes (from 1988 to 2002) in the benthic macroinvertebrate communities of 17 acid-sensitive lakes to evaluate the relationship between benthic community structure and water chemistry associated with acidification. Over the 15 years, chemical variables were found to explain 45-87% of the total variation in the benthic community. Temporal changes in community structure were most apparent from 1991 to 1999, while chemical parameters explained the greatest amount of variance from 1993 to 1997. During this period, relationships were evident between specific invertebrate groups and a number of chemical parameters, with covariables such as calcium and sodium often explaining significant additional variation. Overall, the correlation between benthic community structure and water chemistry suggests a strong association between temporal changes in the macroinvertebrate community and changes in lake chemistry associated with acidification and gradual recovery.

Reid, R. A.; Bowman, M. F.; Somers, K. M.; Lento, J.; Dillon, P.; Somers, K.

2005-05-01

428

The mobilisation of sediment and benthic infauna by scallop dredges.  

PubMed

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

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

2013-09-01

429

Terby's Layers  

NASA Technical Reports Server (NTRS)

2 November 2005 This Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) image shows light-toned, layered, sedimentary rock exposures in Terby Crater, just north of Hellas Planitia. These rocks might have formed from sediment deposited in a lake or a larger Hellas-filling sea.

Location near: 28.0oS, 285.4oW Image width: width: 3 km (1.9 mi) Illumination from: upper left Season: Southern Spring

2005-01-01

430

Spatial patterns of benthic megahabitats and conservation planning in the Abrolhos Bank  

NASA Astrophysics Data System (ADS)

Application of sidescan sonar at the regional scale of the Abrolhos Bank, with ground-truthing by remotely operated vehicles and mixed-gas diving operations, revealed a much more complex habitat mosaic than previously recognized. The regional benthic habitat map indicates 8844 km2 of reefs (earlier estimates from remote sensing were around 500 km2) and 20,904 km² of rhodolith habitat—the world's largest continuous bed. Integration of the regional megahabitat map with spatially explicit data on the distribution of marine protected areas (<0.2% of each benthic megahabitat area) and economic activities with the highest potential of environmental impact (fishing, mining, oil and gas exploitation and dredging) reveals the need of a regional scale spatial planning process engaging conflicting sectors.

Moura, Rodrigo Leão; Secchin, Nélio Augusto; Amado-Filho, Gilberto Menezes; Francini-Filho, Ronaldo Bastos; Freitas, Matheus Oliveira; Minte-Vera, Carolina Viviana; Teixeira, João Batista; Thompson, Fabiano Lopes; Dutra, Guilherme Fraga; Sumida, Paulo Yukio Gomes; Guth, Arthur Zigliatti; Lopes, Rubens Mendes; Bastos, Alex Cardoso

2013-11-01

431

Assessing the ecological quality status of a temperate urban estuary by means of benthic biotic indices.  

PubMed

Benthic indices are commonly used tools for assessing the environmental quality, because they represent a simple source of scientific information. However, their performance could vary depending on the application area and perturbation types, thus they should be tested before used in other remote geographic regions. This study aims to test the use of some of the most widely common benthic biotic indices for assessing the environmental quality of Montevideo's coastal zone at a seasonal scale against many physicochemical variables. From all the evaluated indices, AMBI appears to be the most suitable one to assess the environmental quality. The study also allowed us to infer the most relevant physicochemical variables: protein, lipid and heavy metal sediment concentration. Additionally, site-specific threshold effect levels for heavy metals and biopolymers were established, which appear to be useful to determine tolerable levels of such stressors in future assessments or monitoring programs for the study area. PMID:25467169

Hutton, M; Venturini, N; García-Rodríguez, F; Brugnoli, E; Muniz, P

2014-11-12

432

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

PubMed

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

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

2002-01-01

433

Benthic communities along a littoral of the Central Adriatic Sea (Italy)  

NASA Astrophysics Data System (ADS)

Bacteria, meio- and macrofauna were investigated at different depths in a coastal area of the Central Adriatic Sea, yielding information about the composition and abundance of the benthic community. In particular, 14 nematode genera were recorded for the first time in the Upper Adriatic Sea. All communities resulted as being significantly different between inshore and offshore stations, especially when the season interaction was considered. Sediment grain size seemed to be the main natural variable, along with trophic resources, affecting the distribution and composition of these benthic components, whilst there was no clear evidence of competition for food sources and predatory pressure between the communities. Meiofauna appeared the most useful community for detecting disturbances and river influences. In particular, the lowest copepod abundance in the shallow waters seemed to be related to a greater anthropogenic disturbance inshore, whilst meiofaunal abundance and diversity together with the nematode maturity index suggest the influence of the Foglia and Metauro rivers and the small stream Arzilla.

Semprucci, Federica; Boi, Paola; Manti, Anita; Harriague, Anabella Covazzi; Rocchi, Marco; Colantoni, Paolo; Papa, Stefano; Balsamo, Maria

2010-06-01

434

Holocene melt-water variations recorded in Antarctic coastal marine benthic assemblages  

SciTech Connect

Climate changes can influence the input of meltwater from the polar ice sheets. In Antarctica, signatures of meltwater input during the Holocene may be recorded in the benthic fossils which exist at similar altitudes above sea level in emerged beaches around the continent Interpreting the fossils as meltwater proxy records would be enhanced by understanding the modern ecology of the species in adjacent marine environments. Characteristics of an extant scallop assemblage in West McMurdo Sound, Antarctica, have been evaluated across a summer meltwater gradient to provide examples of meltwater records that may be contained in proximal scallop fossils. Integrating environmental proxies from coastal benthic assemblages around Antarctica, over ecological and geological time scales, is a necessary step in evaluating the marginal responses of the ice sheets to climate changes during the Holocene.

Berkman, P.A.

1992-03-01

435

Nitrate Accumulation in Aerobic Hypolimnia: Relative Importance of Benthic and Planktonic Nitrifiers in an Oligotrophic Lake  

PubMed Central

Both nitrate and nitrous oxide accumulate in the hypolimnion of the oligotrophic Lake Taupo, New Zealand, throughout stratification. The two forms of oxidized nitrogen increase in concentration with increasing depth toward the sediments, where the dissolved concentrations of reduced nitrogen are two orders of magnitude higher than concentrations in the overlying water. Nitrification rates were measured by dark [14C]CO2 assays with and without the inhibitor nitrapyrin. The fastest rates were recorded for planktonic nitrifiers in the epilimnion and benthic species in the surficial 2.5 mm of the sediments. Nitrifying bacteria were least active in the deep hypolimnion. Deepwater accumulation of NO3? in Lake Taupo must therefore be a product of benthic rather than planktonic nitrification. PMID:16345852

Vincent, Warwick F.; Downes, Malcolm T.

1981-01-01

436

Preliminary observations on the benthic marine algae of the Gorringe seabank (northeast Atlantic Ocean)  

NASA Astrophysics Data System (ADS)

Examination of marine samples collected in 2006 from the Gettysburg and Ormonde seamounts on the Gorringe seabank southwest of Portugal has revealed 29 benthic Chlorophyta, Phaeophyceae (Ochrophyta), and Rhodophyta that were identified provisionally to genus and to species. Combining lists for the present and a previous expedition brings the total of algae thus far recorded to 48. The brown alga Zonaria tournefourtii and the red alga Cryptopleura ramosa were the most abundant species in the present collections. The kelp Laminaria ochroleuca was present only in the Gettysburg samples while Saccorhiza polyschides was observed only on the Ormonde seamount. Comparisons with the benthic marine algae recorded on seamounts in the mid-Atlantic Azores archipelago show features in common, notably kelp forests of L. ochroleuca at depths below 30 m and Z. tournefortii dominance in shallower waters.

Tittley, Ian; da Silva Vaz Álvaro, Nuno Miguel; de Melo Azevedo Neto, Ana Isabel

2014-06-01

437

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

NASA Technical Reports Server (NTRS)

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.

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

1980-01-01

438

Benthic community of the Savannah River below a peaking hydropower station  

USGS Publications Warehouse

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.

Hudson, Patrick L.; Nichols, S. Jerrine

1986-01-01

439

Assessment of benthic changes during 20 years of monitoring the Mexican Salina Cruz Bay.  

PubMed

In this work a non-parametric multivariate analysis was used to assess the impact of metals and organic compounds in the macro infaunal component of the mollusks benthic community using surface sediment data from several monitoring programs collected over 20 years in Salina Cruz Bay, Mexico. The data for benthic mollusks community characteristics (richness, abundance and diversity) were linked to multivariate environmental patterns, using the Alternating Conditional Expectations method to correlate the biological measurements of the mollusk community with the physicochemical properties of water and sediments. Mollusks community variation is related to environmental characteristics as well as lead content. Surface deposit feeders are increasing their relative density, while subsurface deposit feeders are decreasing with respect to time, these last are expected to be more related with sediment and more affected then by its quality. However gastropods with predatory carnivore as well as chemosymbiotic deposit feeder bivalves have maintained their relative densities along time. PMID:18253853

González-Macías, C; Schifter, I; Lluch-Cota, D B; Méndez-Rodríguez, L; Hernández-Vázquez, S

2009-02-01

440

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

SciTech Connect

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.

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

441

Analysis of selected benthic communities in Florida Everglades with reference to their physical and chemical environment  

USGS Publications Warehouse

Species diversity and numbers of benthic macroinvertebrates were determined at 12 sites, both canals and marshes, in the Everglades of south Florida. The values calculated are used to indicate long-term trends in water quality and variations between study areas. Species diversity at all sites was generally in a range indicative of degraded water quality. The number of organisms per square metre of bottom surface was highly variable ranging from 43 to 8,200 organisms. Chemical analysis of water and bottom material indicated no gross contamination from sewage or agricultural runoff in any of the canals where benthic organisms were collected. Other physical factors such as depth, velocity of flow, substrate type, and water-level fluctuation were responsible for the low species diversities and variable numbers of organisms, rather than contamination from urban or agricultural areas.

Waller, Bradley G.

1976-01-01

442

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

PubMed

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

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

443

Now an empty mudflat: past and present benthic abundances in the western Dutch Wadden Sea  

NASA Astrophysics Data System (ADS)

The benthic fauna of two areas in the western Dutch Wadden Sea, Posthuiswad and Staart van Schieringhals, was described in 1930-1960 and again between 1996 and 2005. Here, we document the changes. Whereas both areas formerly had high densities of species that biogenically structured the intertidal mudflats such as mussels Mytilus edulis and cockles Cerastoderma edule, by 1996 they had shown a tenfold decrease in the densities of molluscs, with no recovery till 2005. Although the number of species of polychaetes and crustaceans may not have changed much, their relative abundance did. Nowadays, more polychaete species are common than before. We briefly discuss whether the changes in benthic community composition could be due to industrial fishery practices or eutrophication effects.

Kraan, Casper; Dekinga, Anne; Piersma, Theunis

2011-03-01

444

1999 Macmillan Magazines Ltd letters to nature  

E-print Network

the Oregon- Washington margin. Tectonics 9, 569±583 (1990). 8. Doig, R. 2300 yr history of seismicity from. Suspended particulate loads and transports in the nepheloid layer of the abyssal Atlantic Ocean. Mar. Geol

Doebley, John

445

Barium content of benthic foraminifera controlled by bottom-water composition  

Microsoft Academic Search

THE carbon isotope ratio (delta13C) and cadmium content (Cd\\/Ca) of benthic foraminifera shells have been used to reconstruct deep-water circulation patterns of the glacial oceans1-7. These tracers co-vary with phosphorus in the modern ocean because they are nearly quantitatively regenerated from sinking biological debris in the upper water column. Hence they can be used to reconstruct the distribution of labile

D. Lea; E. Boyle

1989-01-01

446

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

NASA Astrophysics Data System (ADS)

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.

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

2005-12-01

447

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

Microsoft Academic Search

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.

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

1995-01-01

448

Biogeochemical responses following coral mass spawning on the Great Barrier Reef: pelagic–benthic coupling  

Microsoft Academic Search

This study quantified how the pulse of organic matter from the release of coral gametes triggered a chain of pelagic and benthic\\u000a processes during an annual mass spawning event on the Australian Great Barrier Reef. Particulate organic matter (POM) concentrations\\u000a in reef waters increased by threefold to 11-fold the day after spawning and resulted in a stimulation of pelagic oxygen

C. Wild; C. Jantzen; U. Struck; O. Hoegh-Guldberg; M. Huettel

2008-01-01

449

Spatial differences in the distribution of benthic macroinvertebrates along a springbrook  

Microsoft Academic Search

Benthic samples (n = 54) were collected at three sites along an unshaded, first?order springbrook, 0–3 m, 15–19 m, and 24–27 m below a permanent spring outflow in Mendocino Co., CA, USA. As distance from spring source increased, number of species and species diversity ([Hbar]) decreased, but number of individuals increased. These patterns may have resulted from temperature fluctuation regimes

Vincent H. Resh

1983-01-01

450

Variability, accuracy, and taxonomic costs of rapid assessment approaches in benthic macroinvertebrate biomonitoring  

Microsoft Academic Search

Twenty population and community measures (with structural measures including richness, diversity indices, and biotic indices, and functional measures including functional feeding?group components) that have been proposed for use in benthic biomonitoring were examined in terms of within?habitat variability (using coefficients of variation), accuracy (i.e., indications of impact when impact occurred; no indications of impact when impact did not occur), and

Vincent H. Resh

1994-01-01

451

Impact of nanoflagellate bacterivory on benthic bacterial production in the North Sea  

NASA Astrophysics Data System (ADS)

In situ grazing of benthic heterotrophic nanoflagellates on bacteria was studied in a wide range of sediment types in the North Sea during summer and winter. Grazing rates were measured using the fluorescently labelled bacteria (FLB) technique. Several factors may potentially influence flagellate grazing, viz. temperature, sediment grain size, bacterial abundance and production, flagellate abundance and biovolume. Flagellate grazing rates were related to these variables. Total grazing of the benthic flagellate population was estimated by multiplying flagellate abundance by maximum/minimum grazing rates. A comparison with the total amount of bacterial cells produced provided an estimate of the impact of flagellate bacterivory on benthic bacterial production. Individual grazing rates ranged from 0 to 112 bacteria per flagellate per hour. Grazing rates showed no significant differences between summer and winter and did not correlate significantly with any of the above-mentioned variables. Maximum average grazing rates ranged from 15 to 39 bacteria per flagellate per hour. Minimum average values varied between 1 and 5 bacteria per flagellate per hour. The percentages of benthic bacterial production accounted for by flagellate consumption differ greatly depending on the grazing rate used. Using maximum grazing rates, 2 to 23% of the bacterial production during summer was consumed, while in winter this ranged from 23 to 528%. Minimum estimates were 10 to 20 times lower: 0.2 to 3% in summer and 1 to 50% in winter, higher percentages of the bacterial production were consumed, which was probably due to the relatively lower bacterial production in winter compared to summer.

Hondeveld, Bea J. M.; Nieuwland, Gerard; Van Duyl, Fleur C.; Bak, Rolf P. M.

452

Benthic bacterial production and protozoan predation in a silty freshwater environment.  

PubMed

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 standing stock of bacteria and protozoa, bacterial secondary production (BSP, (3)H-thymidine, and (14)C-leucine incorporation), and grazing rates of HNF and ciliates on bacteria (FLB uptake) in the oxic sediment of the investigated system. BSP ranged from 470 to 4050 micro g C L(-1) wet sediment h(-1). The bacterial compartment turned out to be highly dynamic, indicated by population doubling times (0.6-10.0 d), which were comparable to those in the water column of the investigated system. Yet, the control mechanisms acting upon the bacterial population led to a relative constancy of bacterial standing stock during a year. Ingestion rates of protozoan grazers were 0-20.0 bacteria HNF(-1) h(-1) and 0-97.6 bacteria ciliate(-1) h(-1). HNF and ciliates together cropped 0-14 (mean 4)% of BSP, indicating that they did not significantly contribute to benthic bacterial mortality during any period of the year. The low impact of protozoan grazing was due to the low numbers of HNF and ciliates in relation to bacteria (1.8-3.5 x 10(4) bacteria HNF(-1), 0.9-3.1 x 10(6) bacteria ciliate(-1)). Thus, grazing by HNF and ciliates could be ruled out as a parameter regulating bacterial standing stock or production in the sediment of the investigated system, but the factors responsible for the limitation of benthic protistan densities and the fate of benthic BSP remained unclear. PMID:12739079

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

2003-07-01

453

The Role of Biodiversity in the Functioning of Freshwater and Marine Benthic Ecosystems  

Microsoft Academic Search

Empirical studies investigating the role of species diversity in sustaining ecosystem processes have focused primarily on terrestrial plant and soil communities. Eighteen representative studies drawn from post-1999 literature specifically examined how changes in biodiversity affect benthic ecosystem processes. Results from these small-scale, low-diversity manipulative studies indicate that the effects of changes in biodiversity (mostly synonymous with local species richness) are

ALAN P. COVICH; MELANIE C. AUSTEN; FELIX BÄRLOCHER; ERIC CHAUVET; BRADLEY J. CARDINALE; CATHERINE L. BILES; PABLO INCHAUSTI; OLIVIER DANGLES; MARTIN SOLAN; MARK O. GESSNER; BERNHARD STATZNER; BRIAN MOSS

2004-01-01

454

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

USGS Publications Warehouse

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

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

1993-01-01

455

The dynamics of benthic microbial communities at Davies Reef, central Great Barrier Reef  

Microsoft Academic Search

The dynamics of benthic microbial communities were examined within different functional zones (reef crest, reef flat, lagoon) of Davies Reef, central Great Barrier Reef, in winter. Bacterial numbers did not change significantly across the reef with a mean abundance \\u000a$$(\\\\bar x{\\\\text{ }} \\\\pm {\\\\text{ 1 SE)}}$$\\u000a of 1.3 (±0.6) x 109 cells g-1 DW of sediment. Bacterial production, measured as

L. A. Hansen; D. M. Alongi; D. J. W. Moriarty; P. C. Pollard

1987-01-01

456

Fish Reliance on Littoral–Benthic Resources and the Distribution of Primary Production in Lakes  

Microsoft Academic Search

Pelagic, littoral, and terrestrial resources can all play a role in supporting consumers in lakes. The role of benthic algal-derived\\u000a food web pathways in lakes is perhaps the least understood because limnologists have historically focused on pelagic (open-water)\\u000a production and processes. We compiled carbon stable isotope data from 546 fish populations (75 lakes), and used a two end-member\\u000a mixing model

M. Jake Vander Zanden; Yvonne Vadeboncoeur; Sudeep Chandra

457

Headwater streams and forest management: Does ecoregional context influence logging effects on benthic communities?  

Microsoft Academic Search

Effects of forest management on stream communities have been widely documented, but the role that climate plays in the disturbance\\u000a outcomes is not understood. In order to determine whether the effect of disturbance from forest management on headwater stream\\u000a communities varies by climate, we evaluated benthic macroinvertebrate communities in 24 headwater streams that differed in\\u000a forest management (logged-roaded vs. unlogged-unroaded,

R. Bruce Medhurst; Mark S. Wipfli; Chris Binckley; Karl Polivka; Paul F. Hessburg; R. Brion Salter

2010-01-01

458

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

NASA Astrophysics Data System (ADS)

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.

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

2013-01-01

459

A time series of benthic flux measurements from Monterey Bay, CA  

Microsoft Academic Search

In situ incubation chamber measurements of benthic nutrient recycling rates were made on the Monterey Bay shelf at 100m during various years and seasons. Variability in nutrient (Si, PO42+, NH3, NO3?) and trace metal (Mn, Fe (II), Cu) fluxes correlate with variability in the amount of organic carbon oxidized on the sea floor. Patterns of primary productivity show a mid-year

William Berelson; Jim McManus; Kenneth Coale; Ken Johnson; David Burdige; Tammy Kilgore; Debbie Colodner; Francisco Chavez; Rafael Kudela; Joceline Boucher

2003-01-01