Sample records for benthic nepheloid layer

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

    SciTech Connect

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

    1995-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    SciTech Connect

    Guo, L. Santschi, P.H.

    2000-02-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    In the southern basin of Lake Lugano, thermal stratification of the water column during summer and autumn leads to a lack of exchange between surface and deep water masses, and consequently to seasonal bottom water anoxia, associated with high methane concentrations. With the onset of bottom water anoxia, a dense layer of high particulate matter concentration - a so-called benthic nepheloid layer (BNL) - develops in the bottom waters. A sharp redox gradient marks the upper boundary of the BNL. At its maximum, the BNL extends 15 - 30 m from the sediment into the water column. We investigated the identity of the BNL and key environmental factors controlling its formation in the framework of a seasonal study. Compound specific C-isotope measurements and Fluorescence In Situ Hybridisation (FISH) of suspended particulate organic matter, radioactive tracer based measurements of methane oxidation, as well as investigation of geochemical water column parameters were performed in spring and autumn. Our analyses revealed that the microbial biomass within the BNL is dominated by methanotrophic bacteria. Aerobic methane oxidation (MOx) was restricted to a narrow zone at the top of the BNL, reaching maximum rates of up to 1.8 ?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.

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

    NASA Astrophysics Data System (ADS)

    Chassefiere, Bernard

    1990-09-01

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

  7. Nepheloid layer dynamics in the northern Portuguese shelf

    NASA Astrophysics Data System (ADS)

    Oliveira, A.; Vitorino, J.; Rodrigues, A.; Jouanneau, J. M.; Dias, J. A.; Weber, O.

    A general hydrographic and nephelometric survey of the NW Portuguese continental shelf and upper slope was undertaken, under winter and spring conditions. The nepheloid layer dynamics along the shelf during three cruises were controlled, principally by the following factors: (a) the hydrography of the shelf-slope waters, i.e. the nepheloid layers followed isopycnals and water masses; (b) prevalence of upwelling or downwelling circulation over the shelf; (c) dispersion of material by river discharge (mainly the Douro river); (d) resuspension of mid-shelf fine deposits induced by swell; (e) peculiar morphology with the presence of Porto Canyon and outer shelf rock outcrops. The general circulation controls the seaward extension of the nepheloid layers. In winter, under dominant downwelling conditions, an intense bottom nepheloid layer (BNL) was observed on the shelf, due to river borne particle supply and remobilization of mid-shelf muddy sediments (depth ?100 m). In this period the BNL increased in thickness to the top of the slope, following the isopycnals. Near the shelf-break the BNL detached to form intermediate nepheloid layers (INL). Small INLs appear deeper in some areas of the slope. A surface nepheloid layer (SNL) appears in the surface water over the shelf and slope. In spring, biological particles mainly contribute to the SNL, which is separated from the BNL by a zone of clear water. In winter the SNL is restricted to the inner shelf where there are high inputs of fluvial particles. Downwelling circulation probably induces transport of shelf particles to deeper waters in the BNL. In spring, the predominant circulation was southward (upwelling), the water column was highly stratified, and dispersion of particles in the SNL was offshore.

  8. The nepheloid layer and horizontal sedimentary matter fluxes in the Norwegian Sea

    Microsoft Academic Search

    V. N. Lukashin; A. D. Shcherbinin

    2007-01-01

    In this paper, the results of long-term studies of the nepheloid layer in the Norwegian Sea in the Komsomolets test area are considered. Its principal characteristics such as its thickness, the particulate matter concentration in the\\u000a nepheloid layer, and its standing crop are presented. The nepheloid layer is formed by the near-bottom current, which, together\\u000a with the particulate standing crop,

  9. Nepheloid layer distribution in the Gulf of Valencia, northwestern Mediterranean

    NASA Astrophysics Data System (ADS)

    Ribó, M.; Puig, P.; Salat, J.; Palanques, A.

    2013-02-01

    According to previous studies, the surface circulation of the Gulf of Valencia (GoV) is characterized by a convergence between the southwestward Northern Current carrying old Atlantic Waters (oAW) and the northward intrusions of recent Atlantic Waters (rAW) imported through the Ibiza Channel. This paper focuses on the distribution of the suspended sediment concentration in the GoV obtained from a dense grid of CTD observations in June 1995 during the oceanographic cruise MESO'95 (MESOscale processes). We evaluate the relation between currents, water masses and the nepheloid structure at the time of the survey. Results showed higher suspended sediment concentration (SSC) in the oAW than in the rAW. At the shelf-break depth, an important detachment of particulate matter was observed off Cap La Nao, extending seawards all across the Ibiza Channel. The presence of this intermediate nepheloid layer detachment indicates a preferential off-shelf sediment export at the southern end of the GoV, where the orientation of the continental margin changes, and oAW and rAW merge. On the continental slope, several nepheloid layers detachments were observed between 400 and 600 m, where the Levantine Intermediate Water (LIW) interacts with the seafloor, suggesting the possible presence of internal waves causing sediment resuspension and/or maintaining particles in suspension in the mid-slope region. A bottom nepheloid layer was also observed at deeper locations along the central and southern part of the GoV continental slope, but not at the Ibiza Sill.

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

    E-print Network

    Boss, Emmanuel S.

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

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

    E-print Network

    Boss, Emmanuel S.

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

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

    USGS Publications Warehouse

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

    1986-01-01

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

  13. The importance of subsurface nepheloid layers in transport and delivery of sediments to the eastern Cariaco Basin, Venezuela

    NASA Astrophysics Data System (ADS)

    Lorenzoni, Laura; Thunell, Robert C.; Benitez-Nelson, Claudia R.; Hollander, David; Martinez, Nahysa; Tappa, Eric; Varela, Ramón; Astor, Yrene; Muller-Karger, Frank E.

    2009-12-01

    Optical transmissometer measurements were coupled with particulate organic matter (POM) observations to understand suspended sediment composition and distribution in the eastern Cariaco Basin during the rainy seasons of September 2003 and 2006. Our results suggest that nepheloid layers originating at the mouth of small mountainous rivers discharging into the eastern Basin are a major delivery mechanism of terrigenous sediments to the Basin interior. Intermediate nepheloid layers (INL) were observed near the shelf break (˜100 m) and appear to effectively transport terrigenous material laterally from the shelf to deep waters, thereby providing a plausible supply mechanism of the terrestrial material observed in sediment traps. These findings highlight the importance of small, local rivers in the Cariaco Basin as sources of terrestrial material. In contrast, these nepheloid layers contained only limited POM. When this information is combined with published sediment trap POM data, it suggests that nepheloid layers may not be a primary mechanism for delivering terrigenous POM to the deeper waters of the basin during the rainy season. Rather, BNL may redistribute marine-derived POM from shallow waters to the Basin's interior by providing ballast materials, particularly during episodic events driven by wind and precipitation. Though we have determined that nepheloid layers play an important role in the seaward transport of particulate material in the Cariaco Basin, their composition and temporal variability have not been fully characterized. This is critical to understand lateral particle transport, since nepheloid layers constitute a significant source of sediment to the deep Cariaco Basin.

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

    USGS Publications Warehouse

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

    2008-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2010-12-01

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

  16. Thick bottom nepheloid layers in the western Mediterranean generated by deep dense shelf water cascading

    NASA Astrophysics Data System (ADS)

    Puig, Pere; Madron, Xavier Durrieu de; Salat, Jordi; Schroeder, Katrin; Martín, Jacobo; Karageorgis, Aristomenis P.; Palanques, Albert; Roullier, François; Lopez-Jurado, José Luis; Emelianov, Mikhail; Moutin, Thierry; Houpert, Loïc

    2013-04-01

    The analysis of a compilation of deep CTD casts conducted in the western Mediterranean from 1998 to 2011 has documented the role that dense water formation, and particularly deep dense shelf water cascading off the Gulf of Lions, plays in transporting suspended particulate matter from the coastal regions down to the basin. Deep CTD casts reveal that after the 1999 and 2005-2006 deep cascading events the Western Mediterranean Deep Water (WMDW) was characterized by the presence of a thick bottom nepheloid layer (BNL) that corresponded in thickness with a thermohaline anomaly generated by the mixture of dense waters formed by deep convection in the open sea and by deep cascading. This BNL can be hundreds of meters thick and in the central part of the basin usually exhibits suspended sediment concentrations of <0.1 mg/l above background levels, reaching higher concentrations close to the continental rise, with near-bottom peaks >1 mg/l. After winter 1999 the BNL spread from the Gulf of Lions and the Catalan margin over the northwestern Mediterranean basin, reaching west of the Balearic Islands and the Ligurian Sea, while after winters 2005-2006 the BNL covered the entire western Mediterranean basin. Thickness and concentration of the BNL tend to diminish with time but this trend is highly dependent on the volume of dense water generated, both by convection and cascading. After winter 1999 the BNL signal vanished in one year, but after winters 2005-2006 it lasted for longer and the turbidity signal can still be distinguished at present (2011). Particle size distribution in the BNL reveals the presence of large aggregates up to 1 mm in size formed by a mixture of single particles with the same bimodal grain size distribution as the surface sediments found in the northwestern Mediterranean slope and basin. Results presented in this paper highlight the fact that the WMDW can be periodically affected by the arrival of new dense waters loaded with suspended particles mainly introduced by resuspension processes during major cascading events, being a key process that could ultimately affect deep-sea biogeochemical cycles in the western Mediterranean.

  17. NOAA Technical Memorandum GLERL-124 OBSERVATIONS OF THE INTERMEDIATE AND BENTHIC NEPHELOID LAYERS IN

    E-print Network

    Laboratory, Ann Arbor, MI 48105 Great Lakes Environmental Research Laboratory Ann Arbor, Michigan August 2003 Commonwealth Blvd., Ann Arbor, MI 48105. pubs.glerl@noaa.gov. ACKNOWLEDGEMENTS Thanks go the crew of the RV

  18. Benthic boundary layer processes in the Lower Florida Keys

    Microsoft Academic Search

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

    1997-01-01

    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\\u000a Key West Campaign. The Dry Tortugas and Marquesas Keys test sites were selected by a group of 115 scientists and technicians\\u000a to study benthic boundary layer processes in a carbonate environment controlled by bioturbation and biogeochemical

  19. Evaluation of processes occurring in the bottom nepheloid layer (BNL) of an eastern Mediterranean area using 234Th/238U disequilibria.

    PubMed

    Evangeliou, Nikolaos; Florou, Heleny

    2013-09-01

    Particle-reactive radionuclide (234)Th and its ratios with the conservative (238)U were used to trace the marine processes occurring over short timescales in the bottom nepheloid layer (BNL) of seven stations in the Saronikos Gulf and the Elefsis Bay (Greece) during three seasons (summer 2008, autumn 2008 and winter 2009). Summer was considered as a steady season where low physical processes occur and stratification is well established, autumn as a commutative period and winter as period of extensive trawling and physical activities. The obtained ratio profiles showed excess of (234)Th relative to (238)U in the BNL of the sampling area during summer, caused by the dissolved fraction of (234)Th. During autumn, the situation was different with large (234)Th deficit throughout the water column leading to large export fluxes of particles from the water column. Finally, during winter the ratios showed that predominant phenomenon in the area was likely resuspension of bottom sediments. The resuspension signature was additionally evaluated by total suspended matter (TSM) inventories in the BNL. Despite the intense resuspension, small scavenging of dissolved (234)Th was recorded in the BNL resulting in high residence times of dissolved (234)Th. A 1 order of magnitude difference between dissolved and particulate (234)Th residence times was observed indicating that scavenging from dissolved to particulate (234)Th could be highly variable and, as a result, the Saronikos Gulf is a highly dynamic environment, in terms of temporal and spatial particle uptake and removal. Comparing these values to literature ones consistent results were obtained. The possibility of sediment resuspension in the BNL during winter was amplified by the bloom of phytoplankton resulting in even decreased residence times of particulate (234)Th (average values). In contrast, the respective residence times of the dissolved fraction of (234)Th in the BNL were higher showing a maximum in winter at the stations where resuspension concluded. Nevertheless, (234)Th cycling in the area is not controlled by TSM, probably due to the presence of colloids, which could play an essential role in (234)Th scavenging. PMID:23334526

  20. The Benthic Boundary Layer: Transport Processes and Biogeochemistry

    NASA Astrophysics Data System (ADS)

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

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

  1. Tidal and subtidal variability in the sloping benthic boundary layer

    NASA Astrophysics Data System (ADS)

    White, M.

    1994-04-01

    Observations are presented of the benthic boundary layer (BBL) structure for two sites on the continental slope, west of the British Isles. Variability at the tidal (M2) and subtidal frequencies is discussed. A mean poleward, along-isobath current is present at both sites, with periodic (5-8 days) reversals observed in the flow. These reversals cause a change in the water column stratification close (<100 m) to the seabed. The relationship between the direction of the along- and cross-slope flow, stratification, and the change of temperature in the frictional layer, relative to that above it, is consistent with Ekman veering induced up/downwelling close to the slope. The BBL temperature (density) structure is highly variable at the tidal frequency. There is a periodic variability in the current shear and associated Richardson number (Ri), particularly for the region where the bottom slope is close to critical for the M2 internal tide. Mixed or gravitationally unstable density layers are generated about one buoyancy period after the minimum Ri are observed. The mixed layers are transient, however, and do not persist throughout the tidal cycle. Indirect estimates of the vertical turbulent eddy diffusivity (K?) were made from conductivity-temperature-depth (CTD) yoyo casts, and its variability through a tidal cycle measured. A background level of 10-4 m2 s-1 is estimated with high values O(10-2 m2 s-1) measured for the times associated with the generation of mixed or inverted density layers. A mean value ofK? = 15-50×10-4 m2 s-1 is found. The observations are compared to recent models of the sloping BBL and laboratory experiments, with particular emphasis on the transient nature of the BBL and the influence of internal wave reflection from the slope.

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

    Microsoft Academic Search

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

    2008-01-01

    The significance of the transport of nutrient-rich hypolimnetic water via the benthic boundary layer (BBL) to the productivity of Mono Lake was studied using a coupled hydrodynamic and ecological model validated against field data. The coupled model enabled us to differentiate between the role of biotic components and hydrodynamic forcing on the internal recycling of nutrients necessary to sustain primary

  3. Deep-Sea Research II 49 (2002) 14111421 Bay of Bengal nutrient-rich benthic layer

    E-print Network

    Gordon, Arnold L.

    Circulation Experiment (WOCE) Indian Ocean hydrographic sections, I- 1 and I-9 cross the Bay of Bengal high-nutrient ratios for the biogeochemical anomalies in the benthic layer water are similar to those observed of nutrients only within a confined pool of bottom water is due to a greater degree of ventilation elsewhere

  4. Finite dispersal of a separative nepheloid plume by an internal hydraulic jump in a tropical mountainous river estuary

    NASA Astrophysics Data System (ADS)

    Wu, Jiaxue; Ametistova, Lioudmila; Heron, Malcolm; Lemckert, Charles J.; Kalangi, Patrice

    2006-11-01

    This paper investigates the dynamics of an internal hydraulic jump in a river plume and associated suspended sediment dispersal. Field investigations were undertaken into the river plume generated by the Herbert River, Australia, following a moderate flood event induced by Cyclone Fritz in 2004. The forced plume experiences an abrupt transition from supercritical to subcritical via an internal hydraulic jump, as defined by a mode-1 internal Froude number computed using the phase speeds from the Taylor-Goldstein equation. The hydraulic theory of a two-layer stratified flow was used to identify the plume shape and the mechanical energy loss within the jump. The hydraulic jump energy loss is primarily transferred to the buoyancy-driven potential energy, uplifting the river plume. Intense stratification decreases the bottom stress, damping the resuspension. Therefore, a separative nepheloid dispersal system occurs at the jump section. Both the upper and lower nepheloid flows are confined to the inner shelf, but have different dispersal behaviors and mechanisms. The upper nepheloid flow, which is primarily controlled by advection and settling, satisfies an exponential decay law of the total suspended sediment concentrations versus the offshore distance. The lower nepheloid flow dominated by deposition is detached seaward near the lift-off point of the river plume. A turbidity front associated with the jump may accumulate a large quantity of suspended sediments, enhancing sediment release from the river plume. These findings will promote in-depth understanding of both the cross-shelf sediment dispersal and muddy deposit on the shelf.

  5. 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...

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

    NASA Astrophysics Data System (ADS)

    Gowing, Marcia M.; Wishner, Karen F.

    1986-07-01

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

  7. Leaf litter recycling in benthic and hyporheic layers in agricultural streams with different types of land use.

    PubMed

    Piscart, Christophe; Navel, Simon; Maazouzi, Chafik; Montuelle, Bernard; Cornut, Julien; Mermillod-Blondin, Florian; des Chatelliers, Michel Creuze; Simon, Laurent; Marmonier, Pierre

    2011-09-15

    Changes in land use and intensification of agricultural pressure have greatly accelerated the alteration of the landscape in most developed countries. These changes may greatly disturb the adjacent ecosystems, particularly streams, where the effects of pollution are amplified. In this study, we used the leaf litter breakdown rate to assess the functional integrity of stream ecosystems and river sediments along a gradient of either traditional extensive farming or a gradient of vineyard area. In the benthic layer, the total litter breakdown process integrates the temporal variability of the anthropogenic disturbances and is strongly influenced by land use changes in the catchment even though a low concentration of toxics was measured during the study period. This study also confirmed the essential role played by amphipods in the litter breakdown process. In contrast, microbial processes may have integrated the variations in available nutrients and dissolved oxygen concentrations, but failed to respond to the disturbances induced by vineyard production (the increase in pesticides and metal concentrations) during the study period. The response of microbes may not be sensitive enough for assessing the global effect of seasonal agricultural practices. Finally, the leaf litter breakdown measured in the hyporheic zone seemed mainly driven by microbial activities and was hence more affected by vertical exchanges with surface water than by land use practices. However, the breakdown rate of leaf litter in the hyporheic zone may constitute a relevant way to evaluate the impact on river functioning of any human activities that induce massive soil erosion and sediment clogging. PMID:21794895

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

    NASA Technical Reports Server (NTRS)

    Frewing, K.

    1980-01-01

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

  9. Benthic foraminifera from Capbreton Canyon revisited; faunal evolution after repetitive sediment disturbance

    NASA Astrophysics Data System (ADS)

    Bolliet, T.; Jorissen, F. J.; Schmidt, S.; Howa, H.

    2014-06-01

    At a 650 m deep site in the axis of Capbreton Canyon an 18-cm-thick turbidite was deposited in December 1999. During subsequent campaigns, an almost monospecific fauna of the benthic foraminifer Technitella melo, considered as a pioneer species, was found in May 2000. In 2001 this fauna had disappeared and was replaced by an exceptionally rich fauna strongly dominated by the opportunistic species Bolivina subaenariensis. We present sedimentological, radionuclide and foraminiferal data of new cores, sampled in 2005 and 2011, taken with the aim to study the further evolution of the benthic ecosystem. Cores sampled in 2005 show that in the canyon axis a new, ca. 5 cm thick, turbidite has been deposited. The live benthic foraminiferal faunas were much poorer than in 2001, but still had a high dominance and low diversity, although less extreme than in 2001. We conclude that in the canyon axis, benthic foraminiferal faunas remain in an early stage of ecosystem colonization. It appears that the very thick 1999 turbidite marks an exceptional event. The uncommonly rich faunas observed in 2001 could be a response to the concentration of organic-rich material in the fine-grained top of this deposit. In 2011, cores were sampled at a slightly different site, on the lower canyon flank. The sedimentary sequence here is marked by the absence of coarse turbidite layers, although some levels show slightly increased grain size, and lower 210Pbxs activities, indicative of an admixture with advected older sediments. Live foraminiferal faunas are much more equilibrated, as shown by their higher diversity, lower dominance, and deeper penetration into the sediment. All these characteristics are indicative of a much more stable ecosystem. Dead faunas are present throughout the core, indicating that the levels with slightly elevated grain size are not typical turbidites resulting from hyperpycnal currents (which are characterized by levels barren of foraminifera) but denote other, more long-term sedimentary processes leading to the advection of older material, such as bottom nepheloid layers, or repetitive fine-grained turbidite deposits due to small-scale slumping. The comparison of live and dead fauna shows that at both sites, the foraminiferal turnover rates are fairly low. At the lower canyon flank site sampled in 2011, the foraminiferal faunas are renewed every 1.5-2 years. Such a fairly long foraminiferal lifespan corresponds to earlier estimates, but is surprisingly high for the opportunistic taxa that dominate the faunal assemblages in these unstable and food-enriched submarine canyon settings.

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

    PubMed Central

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

    2014-01-01

    Phototrophs underpin most ecosystem processes, but to do this they need sufficient light. This critical resource, however, is compromised along many marine shores by increased loads of sediments and nutrients from degraded inland habitats. Increased attenuation of total irradiance within coastal water columns due to turbidity is known to reduce species' depth limits and affect the taxonomic structure and architecture of algal-dominated assemblages, but virtually no attention has been paid to the potential for changes in spectral quality of light energy to impact production dynamics. Pioneering studies over 70 years ago showed how different pigmentation of red, green and brown algae affected absorption spectra, action spectra, and photosynthetic efficiency across the PAR (photosynthetically active radiation) spectrum. Little of this, however, has found its way into ecological syntheses of the impacts of optically active contaminants on coastal macroalgal communities. Here we test the ability of macroalgal assemblages composed of multiple functional groups (including representatives from the chlorophyta, rhodophyta and phaeophyta) to use the total light resource, including different light wavelengths and examine the effects of suspended sediments on the penetration and spectral quality of light in coastal waters. We show that assemblages composed of multiple functional groups are better able to use light throughout the PAR spectrum. Macroalgal assemblages with four sub-canopy species were between 50–75% more productive than assemblages with only one or two sub-canopy species. Furthermore, attenuation of the PAR spectrum showed both a loss of quanta and a shift in spectral distribution with depth across coastal waters of different clarity, with consequences to productivity dynamics of diverse layered assemblages. The processes of light complementarity may help provide a mechanistic understanding of how altered turbidity affects macroalgal assemblages in coastal waters, which are increasingly threatened by diminishing light quantity and altered spectral distributions through sedimentation and eutrophication. PMID:25438045

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

    PubMed

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

    2014-01-01

    Phototrophs underpin most ecosystem processes, but to do this they need sufficient light. This critical resource, however, is compromised along many marine shores by increased loads of sediments and nutrients from degraded inland habitats. Increased attenuation of total irradiance within coastal water columns due to turbidity is known to reduce species' depth limits and affect the taxonomic structure and architecture of algal-dominated assemblages, but virtually no attention has been paid to the potential for changes in spectral quality of light energy to impact production dynamics. Pioneering studies over 70 years ago showed how different pigmentation of red, green and brown algae affected absorption spectra, action spectra, and photosynthetic efficiency across the PAR (photosynthetically active radiation) spectrum. Little of this, however, has found its way into ecological syntheses of the impacts of optically active contaminants on coastal macroalgal communities. Here we test the ability of macroalgal assemblages composed of multiple functional groups (including representatives from the chlorophyta, rhodophyta and phaeophyta) to use the total light resource, including different light wavelengths and examine the effects of suspended sediments on the penetration and spectral quality of light in coastal waters. We show that assemblages composed of multiple functional groups are better able to use light throughout the PAR spectrum. Macroalgal assemblages with four sub-canopy species were between 50-75% more productive than assemblages with only one or two sub-canopy species. Furthermore, attenuation of the PAR spectrum showed both a loss of quanta and a shift in spectral distribution with depth across coastal waters of different clarity, with consequences to productivity dynamics of diverse layered assemblages. The processes of light complementarity may help provide a mechanistic understanding of how altered turbidity affects macroalgal assemblages in coastal waters, which are increasingly threatened by diminishing light quantity and altered spectral distributions through sedimentation and eutrophication. PMID:25438045

  12. Heinrich Events / DC Layers: Benthic Foraminiferal Evidence of Changes in Bottom-Water Characteristics and Circulation During Periods of Rapid Deglaciation

    NASA Astrophysics Data System (ADS)

    Miller, A. A.; Lewis, C. M.; Piper, D. J.

    2004-05-01

    Sudden, large-volume iceberg influxes into the Atlantic Ocean during deglacial episodes throughout the Wisconsinan are inferred by the presence of Heinrich Events (HE), sediment layers with abundant ice-rafted detritus (IRD). In the western North Atlantic, from Cumberland Sound south to Newfoundland, cores contain IRD layers composed predominantly of detrital carbonate (DC), the result of grounded ice eroding Paleozoic carbonate bedrock flooring Hudson Strait and areas of the Canadian Continental Margin. There is a strong to coincident correlation between most HE and DC layers; both contain a marked drop in the abundance of planktic foraminiferal tests, due to both increased sedimentation rates and reduced sea-surface salinities. Evidence indicates that some HE / DC layers correlate to known periods of meltwater influx, and the youngest HE / DC layer correlates to meltwater outflow from glacial Lake Agassiz through Hudson Strait, a massive outburst as the Laurentide Ice Sheet over Hudson Bay underwent final collapse, disrupting thermohaline circulation throughout the North Atlantic. Evidence for changes in the characteristics and circulation of bottom waters are found in the benthic foraminiferal faunas, and they have been utilized to determine more about the bottom-water changes during periods of rapid deglaciation. In a sampling of two shelf and two upper slope areas (all with at least one C-14 AMS date), short-lived, sharp-boundaried increases in the occurrences of deglacial benthic foraminiferal species, species known to tolerate reduced salinities, appear, indicating that either the meltwater flux extended throughout the water column, or that meltwater volumes were large enough to reduce bottom-water salinities when meltwater mixed with the water mass. In the northern Labrador Slope core (97-16), 3 DC layers are present (DC1, DC2, DC3) and deglacial foaraminferal assemblage (DFA) sequences show a strong correlation to the DC layers. In the Notre Dame Channel (Outer Northeast Newfoundland Shelf) core (83-7) three DC layers (DC-1, DC0, DC1) are present. Icebergs / meltwater from Hudson Strait (including Lake Agassiz) flowed south above the upper slope during DC-1 and DC0, forcing displacement of slope bottom waters and their coincident faunas into the basins of the outer shelf, followed by meltwater mixing, and DFA sequences replacing the slope species. In the Flemish Pass (Newfoundland Slope) core (99-4), 7 DC layers are present, including DC layer 5a; DFA sequences are associated with DC1, DC2, and DC3, and the faunas between HE / DC layers are glacial in nature. However, prior to DC3, there were very different faunas present, indicating major changes in bottom-water characteristics and circulation after DC3. Faunas prior to DC3 were dominated by a few species found rarely living today in the slope sediments of the continental margin. At the Halibut Channel site (western Grand Banks) (core 87B-2) there is good chronological control, the DFA sequences occur at H0, H1, and H2. Benthic foraminifera aid in determining bottom-water characteristics and circulation; and the interaction between bottom and surface waters during periods of rapid deglaciation.

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

    Microsoft Academic Search

    Joan E. Cartes

    1998-01-01

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

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

    PubMed Central

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

    2012-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

    The food web structure and diets of 26 taxa of benthic boundary layer (BBL) zooplankton on the Beaufort Sea shelf were studied using carbon and nitrogen stable isotopes and fatty acids. Mean ?15N values ranged from 7.3‰ for the amphipod Melita formosa to 14.9‰ for an unidentified polychaete, suggesting that taxa sampled came from three trophic levels. For 8 taxa, the lightest carbon signature occurred near the mouth of the Mackenzie River. Stable isotope ratios helped clarify the origin of signature fatty acids. Levels of certain polyunsaturated fatty acids (PUFA) were negatively correlated with ?15N, with the exception of 22:6?3, which was positively correlated with ?15N, suggesting that this essential PUFA was retained through the food web. Discriminant analysis proved to be a powerful tool, predicting taxa from fatty acid profiles with 99% accuracy, and revealing strong phylogenetic trends in fatty acid profiles. The amphipod Arrhis phyllonyx had higher levels of ?6 PUFA, especially 20:4?6 with several possible sources, than other peracarid crustaceans. The holothurian had high levels of odd numbered and branched chain fatty acids, indicative of bacterial consumption, while fatty acids of phytoplankton origin were important discriminants for Calanus hyperboreus and the chaetognaths Eukrohnia hamata and Parasagitta elegans. This relationship indicates that the conventional phytoplankton-copepod-chaetognath food web found in the water column also exists in the BBL. This observation, as well as generally low ?15N and high levels of certain PUFA in samples with lower ?15N, strongly suggests that BBL zooplankton on the Beaufort Sea shelf have access to fresh material of phytoplankton origin either by feeding on sedimenting matter or by active migration to surface waters.

  16. Benthic Invertebrate Biomonitoring

    NSDL National Science Digital Library

    1999-01-01

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

  17. Annual growth layers as proxies of past growth conditions for benthic microbial mats in a perennially ice-covered Antarctic lake.

    PubMed

    Sutherland, Donna L; Hawes, Ian

    2009-02-01

    Perennial microbial mats can be the dominant autotrophic community in Antarctic lakes. Their seasonal growth results in clearly discernible annual growth layering. We examined features of live microbial mats from a range of depths in Lake Hoare, Antarctica, that are likely to be preserved in these layers to determine their potential as proxies of past growth performance. Cyanobacteria dominated the mat for all but the deepest depth sampled. Changes in areal concentrations of phycobilin pigments, organic matter and extracellular polysaccharide and in species composition did not correspond to changes in various water column properties, but showed a linear relationship with irradiance. Carbonate accumulation in the mats correlated with biomass markers and may be inferred as an index of mat performance. We examined the carbonate content of annual layers laid down from 1958-1959 to 1994-1995 in sediment cores from 12 m depth. The carbonate content in the layer showed a significant correlation with the mean summer air temperature. These data suggest a link between air temperature and microbial mat growth performance, and suggest that it is mediated via irradiance. Laminated microbial mats in Antarctic lakes have the potential to act as fine-resolution records of environmental conditions in the recent past, although interpretation is complex. PMID:19120468

  18. Benthic-Pelagic coupling in the Black Sea northwestern shelf

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    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.

  19. Seafloor Geomorphology as Benthic Habitat

    E-print Network

    Wright, Dawn Jeannine

    #12;Seafloor Geomorphology as Benthic Habitat Peter T. Harris Senior Marine Science Advisor #12;Seafloor Geomorphology as Benthic Habitat. DOI: © 2012 Elsevier Inc. All rights reserved.2012 100058 58 Abstract We present the geomorphology of the Eastern Samoa Volcanic Province, covering 28,446km

  20. Hydrophobicity as an Adhesion Mechanism of Benthic Cyanobacteria

    PubMed Central

    Fattom, Ali; Shilo, Moshe

    1984-01-01

    The capacity of benthic cyanobacteria to adhere to solid substrates was examined in terms of their cell surface properties. By using a biphasic water-hydrocarbon test system, it was demonstrated that benthic cyanobacteria from divergent habitats were all hydrophobic, whereas all the planktonic cyanobacteria tested were hydrophilic. Divalent cations were found more efficient than monovalent cations in effecting the expression of hydrophobicity. Mechanical shearing of the cell surface, as well as chemical removal of the cell wall, demonstrated that the hydrophobicity was confined to the outer surface layers. The hydrophobic sites were distributed along the whole length of the cyanobacterial filament. Hydrophilic hormogonia of benthic cyanobacteria became hydrophobic within 48 h when grown in the light; chloramphenicol, 3(3,4-dichlorophenyl)1,1 dimethylurea, or incubation in the dark prevented this transition. Hydrophobicity of Phormidium filaments was masked in late stationary phase; this effect was removed by gentle washing. Images PMID:16346453

  1. 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...

  2. Layers

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    The temperature-dependent photoresponse characteristics of MnAl2S4 layers have been investigated, for the first time, by use of photocurrent (PC) spectroscopy. Three peaks were observed at all temperatures. The electronic origin of these peaks was associated with band-to-band transitions from the valence-band states ?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.

  3. Verification of flux measurements made with in situ benthic chambers

    NASA Astrophysics Data System (ADS)

    Devol, Allan H.

    1987-06-01

    Exchange of solutes between the sediments and overlying water was measured in situ at two locations where the overlying waters were devoid of dissolved oxygen (Skan Bay, Alaska and the Tres Marias depression on the Mexican continental shelf). Measurements were made with a tripod capable of collecting eight sequential samples for analysis of dissolved gases and ions. The tripod also permitted tracer injection and the retrieval of sediments underlying the flux chambers. Because of the absence of oxygen, sediments from these areas did not contain benthic faunal populations, and it was possible to compare the benthic fluxes measured with the tripod with those calculated from pore water profiles. For solutes for which exchange was not limited by resistance in the diffuse sublayer (alkalinity, Si(OH) 4+, NH 4+, and PO 43-), tje 11 tirpod-measured fluxes agreed with those calculated from pore water gradients to within 25%. Benthic boundary layer thickness within the chambers as calculated from the initial rate of radiotracer uptake (tritiated water) varied from 405 to 605 ?m in stirred chambers. Measured rates of NO 3- uptake were concordant with a boundary layer thickness of 600 ?m.

  4. PARASITES OF BENTHIC AMPHIPODS: DINOFLAGELLATES (DUBOSCQUODINIDA: SYNDINIDAE)

    E-print Network

    PARASITES OF BENTHIC AMPHIPODS: DINOFLAGELLATES (DUBOSCQUODINIDA: SYNDINIDAE) PHYLLIS T. JOHNSON' ABSTRACf During a 2'f2-yr survey, 13 species of benthic amphipods collected from the continental shelf%, depending on amphipod species, time, and place of collection. The parasites are assigned to the order

  5. Impact of a flood event on benthic and pelagic coupling in a sub-tropical east Australian estuary (Brunswick)

    NASA Astrophysics Data System (ADS)

    Eyre, Bradley D.; Ferguson, Angus J. P.

    2006-01-01

    We examined the impact of a 1:3 year return period flood on benthic and pelagic coupling in the river-dominated sub-tropical Brunswick Estuary. The flood had a significant impact on the study site flushing it with freshwater, reducing the flushing time 0.6 days, increasing nutrient concentrations in the water column and scouring the sediment surface. In the three weeks post-flood the benthic and pelagic systems alternated between being coupled and un-coupled via dissolved, particulate and living material pathways. Immediately post-flood benthic and pelagic coupling via the deposition of phyto-detritus and viable algal cells was reduced due to the scouring of the top sediment layers, and benthic respiration and productivity and NH 4+ effluxes all decreased correspondingly. In contrast, benthic and pelagic coupling was enhanced via the uptake and denitrification of NO 3- due to elevated NO 3- concentrations in the water column. Some of the NO 3- consumed by the sediments may have also been converted to DON. Two weeks post-flood benthic and pelagic coupling was significantly enhanced via the deposition of phyto-detritus and viable algal cells associated with a phytoplankton bloom in the water column. This increased supply of phyto-detritus and viable algal cells rapidly increased benthic respiration and productivity and NH 4+ efflux. The depletion of water column DIN by the phytoplankton bloom resulted in a de-coupling of the benthic and pelagic systems via the uptake and denitrification of NO 3-. However, benthic and pelagic coupling was enhanced via the uptake of NH 4+ by benthic microalgae. Three weeks post-flood the phytoplankton bloom had collapsed and the coupling between the benthic and pelagic systems via the deposition of phyto-detritus and living algal cells had diminished. Again benthic and pelagic coupling was enhanced via the uptake and denitrification of NO 3- due to elevated NO 3- concentrations in the water column associated with the recycling of bloom material. Overall the sediments became less heterotrophic (increasing benthic productivity/respiration ratio) following the flood. Floods can cause rapid and complex changes in the coupling between benthic and pelagic systems in sub-tropical estuaries.

  6. 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...

  7. Feasibility of remote sensing benthic microalgae

    NASA Technical Reports Server (NTRS)

    Zingmark, R. G.

    1979-01-01

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

  8. EPA'S BENTHIC HABITAT DATA FOR YAQUINA ESTUARY

    EPA Science Inventory

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

  9. Particle Transport Processes in a Small Marine Bay

    NASA Astrophysics Data System (ADS)

    Baker, Edward T.; Cannon, Glenn A.; Curl, Herbert C.

    1983-11-01

    Particle transport in Elliott Bay, a 20 km2 embayment in Puget Sound, Washington, was studied in an integrated program employing shipboard CTD/transmissometer observations, moored sediment traps, and moored transmissometer/current meter observations. Surface and bottom high/turbidity layers are present throughout the bay during both summer and winter seasons. Particles added to the surface layer by river input and phytoplankton production are rapidly advected out of the bay and provide only a minor contribution to the local sedimentation rate. The benthic nepheloid layer is maintained not by local resuspension but by particles advected into Elliott Bay with turbid deep water from the adjoining Main Basin of Puget Sound. A severalfold drop in mean current speed as Main Basin water enters Elliott Bay results in increased particle fallout within the benthic nepheloid layer, a high sedimentation rate, and the embayment functioning as a sink for particles from throughout Puget Sound.

  10. 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 ...

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    E-print Network

    Notre Dame, University of

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

  13. 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

  14. Geophysical Conceptual Model for Benthic Flux and Submarine Groundwater Discharge

    Microsoft Academic Search

    J. N. King

    2010-01-01

    Numerous investigators characterize benthic flux and submarine groundwater discharge (SGD) using a geochemical conceptual model that relies on the estimation of tracer fluxes into and out of a control volume. (Benthic flux is the rate of flow across the bed of any water body, per unit area of bed. Benthic flux is a vector that includes both discharge and recharge

  15. Woody Vegetation Removal Stimulates Riparian and Benthic

    E-print Network

    Dodds, Walter

    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

  16. Accumulation of Po by benthic marine algae

    Microsoft Academic Search

    R. C. Gouvea; M. E. Castelo Branco; P. L. Santos; V. A. Gouvea

    1988-01-01

    The accumulation of polonium Po by various species of benthic marine seaweeds collected from 4 different points on the coast of Rio de Janeiro, RJ (Brasil), showed variations by species and algal groups. The highest value found was in red alga, Plocamium brasiliens is followed by other organisms of the same group. In the group of the brown alga, the

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

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

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

    PubMed

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

    2011-01-01

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

  19. Impacts of bioturbation on the age difference between benthic and planktonic foraminifera in deep sea sediments

    SciTech Connect

    Peng, T.H.; Broecker, W.S.

    1984-01-01

    Accelerator mass spectrometry offers for the first time the opportumity to date hand-picked planktonic (surface-swelling) and benthic (bottom-dwelling) foraminifera from deep sea cores, making it possible to reconstruct temporal changes in the rate of deep ocean ventilation. There is, however, a serious problem in interpreting such results. Bioturbation of the soil zone in the upper has two subtle influences that lead to biases in the results. One involves changes with time in the abundances of the forams in newly deposited sediment. The other concerns dissolution effects on the forams during their residence within the bioturbated layer. Mixing models are presented in this paper that illustrate the effects of these interactions on the /sup 14/C age difference between benthic and planktonic species. 9 references, 12 figures.

  20. Benthic diatom response to changing environmental conditions

    NASA Astrophysics Data System (ADS)

    Cibic, Tamara; Comici, Cinzia; Bussani, Andrea; Del Negro, Paola

    2012-12-01

    In the Gulf of Trieste (northern Adriatic Sea, Italy) the benthic diatom community dynamics has been studied for seven years (1999-2005) at two sublittoral stations and related to variations of temperature, salinity, nutrient concentrations, freshwater inflow and mucilage. Bin-averaged temperature versus abundance of the main genera revealed that Nitzschia and Navicula presented a positive stepped trend with increasing temperature. An increase of ca. 860 ± 150 cells per cm3 per °C was calculated for Navicula and up to 590 ± 170 cells per cm3 per °C for Nitzschia. The genus Pleurosigma revealed a negative trend with increasing temperature, with a calculated decrease of ca. 140 ± 60 cells per cm3 per °C. A negative relation between Diploneis and temperature was found only in the shallower site. A peak of the tychopelagic genus Cylindrotheca was observed in correspondence with high salinity, but no significant results between bin-averaged salinity and benthic diatom abundance were found. Significant negative relations were obtained between bin-averaged abundance of Pleurosigma and H4SiO4 and NO3- at the deeper station and between the bin-averaged abundance of Gyrosigma and NH4+ at the coastal station. In this site the abundance of Gyrosigma showed a significant increasing trend over the study period. Navicula and Nitzschia seemed to suffer from the presence of mucilage events occurred in summer 2000 and 2004 whereas Diploneis occupied the ecological niche which remained temporarily uncovered by Navicula and Nitzschia. An exceptional freshwater plume with extremely high terrigenous input in November 2000 completely covered the benthic diatom community, causing a remarkable decrease in its total abundance in late autumn and winter 2000-01. The Gulf of Trieste may be considered a natural megacosm due to its geomorphologic characteristics and therefore the benthic diatom response to changing environmental conditions observed in this site could be extended beyond the geographical limits of this particular ecosystem.

  1. Microbial mediation of benthic biogenic silica dissolution

    NASA Astrophysics Data System (ADS)

    Holstein, Jan M.; Hensen, Christian

    2010-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2009-04-01

    Since the changes in the economies in the Black Sea countries in the 1990's, the momentarily associated decrease in anthropogenic pressures has put the ecosystem of Black Sea western shelf on a trajectory to recovery. However, the suspected non-linearity of recovery and the ecological instability of the benthic shelf ecosystem in particular became evident in the field surveys supported by the BSERP in 2003, 2004, 2005 and 2006, e.g. in the spread of opportunistic species taking new niches and the re-occurrence of large-scale bottom water hypoxia like in 2001. The temporal dynamics of the recovery (as well as of the decline) may also be tied to climatic effects. The Black Sea is known to respond to north Atlantic oscillation (NAO) forcing and decadal climate changes. The target of the 363th cruise of R/V Poseidon in March 2008 has been to map the current state of the benthic ecosystem in a quasi-winter situation. We assessed: a) the current state of the benthic ecosystem on the north-western shelf; to what degree it recovered during the past decade from its collapse in the 1980's. In this respect, we investigated the role of the seabed as storage media of nutrients from past eutrophication, and the role of the sediments as internal source of nutrients to the pelagic system. We focused on zoo- and phytobenthos distribution, the interaction of benthic biota with the sediment, accumulation of nutrients in the sediment, and the flux of nutrients from the sediments to the water. b) The benthic-pelagic coupling, i.e. how the nutrients nitrogen, phosphorus and silica for algal growth are transported from the seafloor to the sea surface and thus fuel biologic productivity. c) The exchange of water between the shelf and the open Black Sea, and hence the transport of nutrients, i.e. the fertilization of the open Black Sea with nutrients from the shelf. Here, we are presenting results from the spring 2008 survey and compare them to findings from a summer survey in 2006: thermal heating and freshwater input created a double front structure on the western shelf, and intrusion of the Cold Intermediate Layer (CIL) into shelf waters was observed. Surface distribution of dissolved nutrients reflects clear signals of silica and total dissolved nitrogen input from the Danube River. Phosphate appears to have a different source, e.g. benthic and/or from the CIL. The benthic ecosystem remains fragile; diversity indices reflect small recovery, quantities in biomass of both zoo- and phytobenthos indicate ongoing perturbations in nearshore areas. A full recovery of historical beds of Phyllophora is not evident, coverage both in winter and summer is less than 10%, and its role as habitat could be compromised by overgrowth of filamentous algae. The benthic system with an epibenthic community in balance releases less nutrients than a disturbed system without benthic life. Nutrients release from the sediment is lower in winter than in summer. The oxygen penetration depth in the sediment triggers denitrification. A spectacular population development of opportunistic species both in zoo- and phytobenthos was observed. The question remains whether or not those opportunistic species can ensure ecosystem functionality and stability. Our findings will help to identify locations crucial for the functioning for the benthic shelf ecosystem, to define "Good Environmental Status" and help to provide recommendations for Marine protected areas on the western Black Sea shelf. It is hoped that the data will make an important contribution to the information base underpinning the new European Marine Strategy Directive and the Bucharest Convention for the Protection of the Black Sea.

  3. A Process for Comparing and Interpreting Differences in Two Benthic Indices in New York Harbor

    EPA Science Inventory

    Often when various estuarine benthic indices disagree in their assessments of benthic condition, they are reflecting different aspects of benthic condition. We describe a process to screen indices for associations and, after identifying candidate metrics, to evaluate metrics indi...

  4. 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...

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

    USGS Publications Warehouse

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

    1982-01-01

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

  6. Benthic fluxes in San Francisco Bay

    USGS Publications Warehouse

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

    1985-01-01

    Measurements of benthic fluxes have been made on four occasions between February 1980 and February 1981 at a channel station and a shoal station in South San Francisco Bay, using in situ flux chambers. On each occasion replicate measurements of easily measured substances such as radon, oxygen, ammonia, and silica showed a variability (??1??) of 30% or more over distances of a few meters to tens of meters, presumably due to spatial heterogeneity in the benthic community. Fluxes of radon were greater at the shoal station than at the channel station because of greater macrofaunal irrigation at the former, but showed little seasonal variability at either station. At both stations fluxes of oxygen, carbon dioxide, ammonia, and silica were largest following the spring bloom. Fluxes measured during different seasons ranged over factors of 2-3, 3, 4-5, and 3-10 (respectively), due to variations in phytoplankton productivity and temperature. Fluxes of oxygen and carbon dioxide were greater at the shoal station than at the channel station because the net phytoplankton productivity is greater there and the organic matter produced must be rapidly incorporated in the sediment column. Fluxes of silica were greater at the shoal station, probably because of the greater irrigation rates there. N + N (nitrate + nitrite) fluxes were variable in magnitude and in sign. Phosphate fluxes were too small to measure accurately. Alkalinity fluxes were similar at the two stations and are attributed primarily to carbonate dissolution at the shoal station and to sulfate reduction at the channel station. The estimated average fluxes into South Bay, based on results from these two stations over the course of a year, are (in mmol m-2 d-1): O2 = -27 ?? 6; TCO2 = 23 ?? 6; Alkalinity = 9 ?? 2; N + N = -0.3 ?? 0.5; NH3 = 1.4 ?? 0.2; PO4 = 0.1 ?? 0.4; Si = 5.6 ?? 1.1. These fluxes are comparable in magnitude to those in other temperate estuaries with similar productivity, although the seasonal variability is smaller, probably because the annual temperature range in San Francisco Bay is smaller. Budgets constructed for South San Francisco Bay show that large fractions of the net annual productivity of carbon (about 90%) and silica (about 65%) are recycled by the benthos. Substantial rates of simultaneous nitrification and denitrification must occur in shoal areas, apparently resulting in conversion to N2 of 55% of the particulate nitrogen reaching the sediments. In shoal areas, benthic fluxes can replace the water column standing stocks of ammonia in 2-6 days and silica in 17-34 days, indicating the importance of benthic fluxes in the maintenance of productivity. Pore water profiles of nutrients and Rn-222 show that macrofaunal irrigation is extremely important in transport of silica, ammonia, and alkalinity. Calculations of benthic fluxes from these profiles are less accurate, but yield results consistent with chamber measurements and indicate that most of the NH3, SiO2, and alkalinity fluxes are sustained by reactions occurring throughout the upper 20-40 cm of the sediment column. In contrast, O2, CO2, and N + N fluxes must be dominated by reactions occurring within the upper one cm of the sediment-water interface. While most data support the statements made above, a few flux measurements are contradictory and demonstrate the complexity of benthic exchange. ?? 1985 Dr W. Junk Publishers.

  7. 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)

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

    2014-12-01

    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.

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

    PubMed

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

    2013-02-01

    Triclosan (5-chloro-2-[2,4-dichlorophenoxy]phenol) is a relatively new, commonly used antimicrobial compound found in many personal care products. Triclosan is toxic to marine organisms at the micrograms per liter level, can photodegrade to a dioxin, can accumulate in humans, and has been found to be stable in marine sediments for over 30 years. To determine the effects of triclosan on marine benthic communities, intact sediment cores were brought into the laboratory and held under flowing seawater conditions. A 2-cm layer of triclosan-spiked sediment was applied to the surface, and after a two-week exposure the meio- and macrofaunal communities were assessed for differences in composition relative to nonspiked cores. A high triclosan treatment (180?mg/kg dry wt) affected both the meio- and the macrobenthic communities. There were no discernible differences with a low-triclosan treatment (14?mg/kg dry wt). This exposure method is effective for testing the benthic community response to sediment contaminants, but improvements should be made with regard to the amount and method of applying the overlying sediment to prevent smothering of fragile benthic organisms. PMID:23161706

  9. Classification of threespine stickleback along the benthic-limnetic axis.

    PubMed

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

    2010-11-01

    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

  10. 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...

  11. MDE NON-TIDAL BENTHIC MACROINVERTEBRATE MONITORING PROGRAM

    EPA Science Inventory

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

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

    Microsoft Academic Search

    P. S ILVER BOTTS; BENJAMIN A. PATTERSON

    1996-01-01

    In soft sediments, Dreissena spp. create firm substrate in the form of aggregates of living mussels (druses) that roll free on the sediments. Druses provide physical structure which increases habitat heterogeneity, and the mussels increase benthic organic matter through the production of pseudofeces and feces. Descriptive and experimental studies were used to determine: 1) whether the density of benthic invertebrates

  13. Establishing a Benthic Cabled Observatory with ROV Based Cable Deployment

    Microsoft Academic Search

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

    2006-01-01

    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

  14. ASSESSMENT OF BENTHIC MACROINVERTEBRATE HABITAT SUITABILITY IN A TROPICAL WATERSHED

    Microsoft Academic Search

    Fernanda Horta; Hersília Santos; Lurdemar Tavares; Marianne Antunes; Paulo Pinheiro; Marcos Callisto

    Urban land uses such as deforestation, mining, agriculture, logging and road construction, can cause stream sedimentation, modifying the morphology and depth of the river channel and diminishing the availability of physical habitats. Habitat requirements of benthic macroinvertebrates must be considered in a streamflow management strategy to maintain the biotic integrity. The aim of this study was to develop a benthic

  15. 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...

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

    EPA Science Inventory

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

  17. 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...

  18. Classification of threespine stickleback along the benthic-limnetic axis

    PubMed Central

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

    2010-01-01

    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

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

    USGS Publications Warehouse

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

    2009-01-01

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

  20. 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

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

    PubMed Central

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

    2013-01-01

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

  2. 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...

  3. 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...

  4. 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...

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

    EPA Science Inventory

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

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

    PubMed Central

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

    2013-01-01

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

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

    E-print Network

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

    2011-07-18

    - terial mats (the water was aspirated out of the culture bottle), the texture of the different species’ mats was noted. Specifically, CAWBG26 formed a cohesive mat which was easily picked up with tweezers, whereas the filaments of CAWBG59 were not tightly... , Ryan KG (2010) Polyphasic assessment of fresh-water benthic mat-forming cyanobacteria isolated from New Zealand. FEMS Microbiol Ecol 73(1):95–109. Heubeck S, Craggs R (2007) Resource assessment of algae biomass for potential bioenergy production in New...

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

    NASA Astrophysics Data System (ADS)

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

    2010-07-01

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

  9. Stalk-eyed views of the Gulf of Maine--Through a nepheloid layer dimly School of Marine Sciences, 5706 Aubert Hall, University of Maine, Orono, Maine, 04469-5706

    E-print Network

    Jumars, Pete

    M, Neomysis americana, share both stalked eyes that appear capable of detecting polarized light and statocysts and Puget Sound on North America's opposite and also glacially sculpted coast--but enclosed, large (Jordan, Wilkinson and Georges) and anticyclonic circulation over George's Bank at its outer boundary

  10. Benthic lead fluxes in San Francisco Bay, California, USA

    NASA Astrophysics Data System (ADS)

    Rivera-Duarte, Ignacio; Flegal, A. Russell

    1994-08-01

    Porewater concentration gradients indicate relatively large benthic fluxes of Pb from sediments in the San Francisco Bay estuary. Gradients in total dissolved (<0.45 ?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 × 10 -9 moles m -2 d -1 to 3.1 × 10 -8 moles m -2 d -2 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 -1) is at least an order of magnitude greater than the fluvial input of dissolved Pb to the estuary (0.2 moles d -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 -1) than the estimates of diffusive fluxes. Therefore, the total benthic flux of Pb from the bay's sediments may be within an order of magnitude of the total anthropogenic flux of Pb to the San Francisco Bay estuary (965-8,410 moles d -1).

  11. Ecology and role of benthic copepods in northern lakes

    NASA Astrophysics Data System (ADS)

    Sarvala, J.

    1998-06-01

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

  12. Detecting Benthic Megafauna in Underwater Video

    NASA Astrophysics Data System (ADS)

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

    2004-12-01

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

  13. Change in biomass of benthic and planktonic algae along a disturbance gradient for 24 Great

    E-print Network

    McMaster University

    Change in biomass of benthic and planktonic algae along a disturbance gradient for 24 Great Lakes a content of planktonic algae and benthic algae in periphyton on acrylic rods and in epiphyton growing

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

    EPA Science Inventory

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

  15. 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...

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

    EPA Science Inventory

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

  17. 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...

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

    NASA Astrophysics Data System (ADS)

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

    1995-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

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

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

    Microsoft Academic Search

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

    2011-01-01

    Benthic primary producers in marine ecosystems may significantly alter biogeochemical cycling and microbial processes in their surrounding environment. To examine these interactions, we studied dissolved organic matter release by dominant benthic taxa and subsequent microbial remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration, and dissolved organic carbon (DOC) release were assessed for several common benthic

  1. A new approach to mapping marine benthic habitats using physical environmental data

    Microsoft Academic Search

    Zhi Huang; Brendan P. Brooke; Peter T. Harris

    2011-01-01

    Reliable marine benthic habitat maps at regional and national scales are needed to enable the move towards the sustainable management of marine environmental resources. Due to the paucity of adequate biological data and the prohibitive cost of directly sampling benthic biota over large areas, the most effective means of developing broad-scale benthic habitat maps is to use commonly available marine

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

    E-print Network

    Husinec, Antun

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

  3. Benthic macrofaunal community condition in the Southern California Bight, 1994–2003

    Microsoft Academic Search

    J. Ananda Ranasinghe; Kenneth C. Schiff; David E. Montagne; Tim K. Mikel; Donald B. Cadien; Ronald G. Velarde; Cheryl A. Brantley

    2010-01-01

    To assess benthic macrofaunal community condition in Southern California, 838 sites were sampled using spatially random designs in 1994, 1998, or 2003. Benthic community condition was assessed on a four-category scale and the area in each category estimated. Overall, benthic macrofauna in Southern California were in good condition during 2003, with 98% of the area in reference condition or deviating

  4. Shifts in Benthic Algal Community Structure and Function Following the Appearance of Zebra Mussels (Dreissena polymorpha)

    Microsoft Academic Search

    Rex L. Lowe; Robert W. Pillsbury

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

  5. 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...

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

    E-print Network

    Stanton, Tim

    Acoustic scattering by benthic and planktonic shelled animals Timothy K. Stanton and Dezhang Chu of shell Littorina littorea . Benthic and planktonic shelled animals with this shape occur on the seafloor scattering modeling were recently conducted on a type of benthic shelled animal that has a spiral form

  7. 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

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

    EPA Science Inventory

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

  9. 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...

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

    NASA Astrophysics Data System (ADS)

    Thomas, E.; Alegret, L.

    2012-12-01

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

  11. Temporal and Spatial Changes in Bottom-Water Oxygenation in the Japan Sea During the Late Quaternary : The Effects on the Benthic Foraminiferal Assemblages

    NASA Astrophysics Data System (ADS)

    Usami, K.; Ohi, T.; Hasegawa, S.

    2007-12-01

    Late Quaternary hemipelagic sediments in the Japan Sea are characterized by alternating beds of light and dark layers which are synchronous basin-wide and considered to be reflections of bottom-water oxygenation during the depositions (Oba et al., 1991; Tada et al., 1999). In this study, benthic foraminiferal assemblages are analyzed to understand temporal and spatial variations of sea-floor environments during times of dark layer formation for the last 160ka, based on the 3 cores IMAGES MD01-2407 and D-GC-6 recovered at the same position (water depth 932m) in the southeastern Japan Sea, and KR05-09, PC-1 (water depth 1792m) in the northeastern Japan Sea. The dark layers in these cores are classified into six types by dominant species of benthic foraminifera and benthic foraminiferal abundance mainly in the core MD01-2407 (Usami et al., 2007), as follows: Barren-type (almost absent of benthic foraminifera), Angulogerina-type (abundant Angulogerina ikebei), mixture-type (relatively high species diversity and equitability), Islandiella-type (abundant Islandiella norcrossi), Eilohedra-type (abundant Eilohedra nipponica), Brizalina-type (abundant Brizalina pacifica). In the core KR05-09, PC-1, to the contrary, benthic faunas are adopted only three types, barren-type, mixture-type and Brizalina-type. In particular, most of the dark layers from MIS3 to 5b are barren-type, suggesting more severe oxygen depletion in benthic ecosystem of the northeastern Japan Sea. Oba, T., Kato, M., Kitazato, H., Koizumi, I., Omura, A., Sasaki, T., Takayama, T., 1991. Paleoenvironmental changes in the Japan Sea during the last 85,000 years. Paleoceanography 6, 499-518. Tada, R., Irino, T., Koizumi, I., 1999. Land-ocean linkages over orbital and millennial timescales recorded in late Quaternary sediments of the Japan Sea. Paleoceanography 14 (2), 236-247. Usami, K., Ohi, T., Hasegawa, S., 2007. Foraminiferal response to late Quaternary climate variability in the Japan Sea : Concerning low oxygen environment and productivity. 9th International Conference on Paleoceanography [ Shanghai, China ], Abstracts (in press).

  12. 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...

  13. 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...

  14. dam logic: qualitative reasoning about benthic macroinvertebrate responses

    E-print Network

    Tullos, Desiree

    dam logic: qualitative reasoning about benthic macroinvertebrate responses to dam removal desiree tullos oregon state university #12;my damned logic performance evaluation that moves beyond case studied in ecological responses to dam removal" (Heinz 2002) #12;what is QR? Qualitative Reasoning (QR) - logic

  15. risk: lessons from Triassic-Jurassic marine benthic organisms

    Microsoft Academic Search

    Wolfgang Kiessling; Martin Aberhan

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

  16. A time series of benthic fluxmeasurements from Monterey Bay, CA

    Microsoft Academic Search

    William Berelsona; Jim McManusb; Kenneth Coalec; Ken Johnsond; David Burdigee; Tammy Kilgorea; Debbie Colodnerf; Francisco Chavezd; Rafael Kudelag; Joceline Boucherh

    In situ incubation chamber measurements of benthic nutrient recycling rates were made on the Monterey Bay shelf at 100 m during various years and seasons. Variability in nutrient (Si, PO4 2+ ,N H 3 ,N O 3 ? ) and trace metal (Mn, Fe (II), Cu) fluxes correlate with variability in the amount of organic carbon oxidized on the sea

  17. Ecological stoichiometry in freshwater benthic ecosystems: an introduction

    E-print Network

    Benstead, Jon

    and their control from crayfish and snails, a paper addressing the stoichiometric effects on fish and plankton reports exploring the stoichiometry of stromatolites and their snail consumers in a stream fed by thermal that result from benthic food subsidies to fish, a study of the stoichiometry of tree leaves and litter

  18. 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

  19. MAPPING BENTHIC COMMUNITIES IN SOUTHWESTERN PUERTO RICO USING IKONOS

    E-print Network

    Gilbes, Fernando

    MAPPING BENTHIC COMMUNITIES IN SOUTHWESTERN PUERTO RICO USING IKONOS Zayas-Santiago,Carmen C.1 and 2Department of Geology, University of Puerto Rico at Mayagüez Abstract The Center for Subsurface. The University of Puerto Rico at Mayagüez (UPRM) is an important partner of CenSSIS with a multidisciplinary

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

    E-print Network

    Gobas, Frank

    Development and Verification of a Benthic/Pelagic Food Web Bioaccumulation Model for PCB Congeners for environmental managers. Food web bioaccumulation models have been developed that account for many of this model to predict contaminant transfer in a complex food web and its potential applicability to other

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

    E-print Network

    Girguis, Peter R.

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

  2. Comparative Microhabitat Use of Ecologically Similar Benthic Fishes

    Microsoft Academic Search

    Ellen van Snik Gray; Jay R. Stauffer

    1999-01-01

    Although benthic insectivorous fishes such as darters and sculpins represent a significant component of riffle communities, few studies have compared the habitat use of these non-related but ecologically similar fishes. The objectives of this study were to examine the habitat use of Etheostoma olmstedi (tessellated darter) compared to Cottus bairdi (mottled sculpin) in Nescopeck Creek and Cottus cognatus (slimy sculpin)

  3. Microhabitat preferences of benthic fauna in a woodland stream

    Microsoft Academic Search

    Donald J. Orth; O. Eugene Maughan

    1983-01-01

    Estimates of numbers, biomass, and diversity of benthic macroinvertebrates were made quarterly over a two-year period to investigate microhabitat preferences. Although biomass of most taxa was significantly different among sampling times, physical factors also appeared to be important in determining abundance of many taxa. Optimum depth, velocity, substrate type, and turbulence were determined for major taxa. Optimum conditions for diversity

  4. ORIGINAL ARTICLE Alteration of benthic communities associated with copper

    E-print Network

    Levin, Lisa

    .1111/maec.12054 Abstract Although copper (Cu) is an essential element for life, leaching from boat paint canORIGINAL ARTICLE Alteration of benthic communities associated with copper contamination linked; copper contamination; diversity; macrofauna; marina; recreational boats; San Diego Bay sediment

  5. ORIGINAL PAPER Vulnerability of benthic habitats to the aquatic invasive

    E-print Network

    ORIGINAL PAPER Vulnerability of benthic habitats to the aquatic invasive species Anastasija Zaiko Ã? and the sea. Results indicated that invasive species richness (number of alien species per habitat) in lagoon distinguished to be the most important for native and invasive species distribution were salinity, depth range

  6. 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...

  7. FORECASTING EFFECTS OF SEWAGE SOLIDS ON MARINE BENTHIC COMMUNITIES

    EPA Science Inventory

    Solids from marine municipal discharges settle to the sea bottom where they cause major but potentially reversible changes in the biomass and trophic structure of macrobenthic communities. The relationships may be useful in forecasting changes in the size and structure of benthic...

  8. Relating Remotely Sensed Optical Variability to Marine Benthic Biodiversity

    PubMed Central

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

    2013-01-01

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

  9. 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...

  10. NOAA Technical Report NMFS 103 Benthic Macrofauna of the

    E-print Network

    NOAA Technical Report NMFS 103 Benthic Macrofauna of the New York Bight, 1979-89 Robert N. Reid, analyzes, and publishes statistics on various phases of the industry. The NOAA Technical Report NMFS series was estab- lished in 1983 to replace two subcategories of the Tech- nical Report series: "Special Scientific

  11. 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...

  12. Benthic Nitrogen Loss in the Arabian Sea Off Pakistan

    PubMed Central

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

    2012-01-01

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

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

    USGS Publications Warehouse

    Nichols, Frederic H.

    1973-01-01

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

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

    NASA Astrophysics Data System (ADS)

    King, J. N.

    2012-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Tamura, Y.; Tsuchiya, M.

    2011-09-01

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

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

    Microsoft Academic Search

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

    2011-01-01

    Benthic biofilters were deployed under a cage fish farm and in two reference locations to assess the influence of the farm on the biofilters and the surroundings, as well as to verify the usefulness of this technology as a mitigation tool. The biofilters underneath the farm recruited a fouling community practically identical to that of the control biofilters, which included

  17. 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...

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

    NASA Astrophysics Data System (ADS)

    Kelly-Slatten, K.

    2013-12-01

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

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

    USGS Publications Warehouse

    McDougall, K.

    1987-01-01

    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

  20. Spatially stochastic settlement and the coexistence of benthic marine animals.

    PubMed

    Edwards, Kyle F; Stachowicz, John J

    2011-05-01

    For sessile organisms, dispersal and recruitment are typically spatially stochastic, but there is little understanding of how this variability scales up to influence processes such as competitive coexistence. Here we argue that coexistence of benthic marine animals is enhanced by stochastic differences between species in the spatial distribution of larval settlement. Differentiation of settlement distributions among competitors results in intraspecifically aggregated settlement, which can reduce overall interspecific competition and increase overall intraspecific competition. We test for the components of this mechanism using a pair of subtidal invertebrates, and we find that the mean interspecific effect of the dominant competitor is substantially reduced by natural settlement variability. Using a simulation parameterized with experimental data, we find that variable settlement could play an important role in long-term coexistence between these species. This mechanism may apply broadly to benthic marine communities, which can be highly diverse and typically exhibit large settlement fluctuation over a range of scales. PMID:21661570

  1. Age and correlation of California Paleogene benthic foraminiferal stages

    USGS Publications Warehouse

    Poore, Richard Z.

    1980-01-01

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

  2. Impact of different benthic animals on phosphorus dynamics across the sediment-water interface.

    PubMed

    Zhang, Lei; Gu, Xiaozhi; Fanl, Chengxin; Shang, Jingge; Shen, Qiushi; Wang, Zhaode; Shen, Ji

    2010-01-01

    As a diagenetic progress, bioturbation influences solute exchange across the sediment-water interface (SWI). Different benthic animals have various mechanical activities in sediment, thereby they may have different effects on solute exchange across the SWI. This laboratory study examined the impacts of different benthic animals on phosphorus dynamics across the SWI. Tubificid worms and Chironomidae larvae were introduced as model organisms which, based on their mechanical activities, belong to upward-conveyors and gallery-diffusers, respectively. The microcosm simulation study was carried out with a continuous flow culture system, and all sediment, water, and worms and larvae specimens were sampled from Taihu Lake, China. To compare their bioturbation effects, the same biomass (17.1 g wet weight (ww)/m2) was adopted for worms and larvae. Worms altered no oxygen penetration depth in sediment, while larvae increased the O2 penetration depth, compared to the control treatment. Their emergence also enhanced sediment O2 uptake. The oxidation of ferrous iron in pore water produced ferric iron oxyhydroxides that adsorbed soluble reactive phosphorus (SRP) from the overlying water and pore water. Larvae built obviously oxidized tubes with about 2 mm diameter and the maximum length of 6 cm in sediment, and significantly decreased ferrous iron and SRP in the pore water compared to the control and worms treatments. Worms constructed no visually-oxidized galleries in the sediment in contrast to larvae, and they did not significantly alter SRP in the pore water relative to the control treatment. The adsorption of ferric iron oxyhydroxides to SRP caused by worms and larvae inhibited SRP release from sediment. Comparatively, worms inhibited more SRP release than larvae based on the same biomass, as they successively renewed the ferric iron oxyhydroxides rich oxidation layer through their deposition. PMID:21235153

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

    NASA Astrophysics Data System (ADS)

    Kim, Tae-Hoon; Kim, Guebuem

    2014-12-01

    The activities of colloidal (10 kDa-0.45 ?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.

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

    PubMed Central

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

    2014-01-01

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

  5. A Benthic Terrain Classification Scheme for American Samoa

    Microsoft Academic Search

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

    2006-01-01

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

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

    NSDL National Science Digital Library

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

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

    USGS Publications Warehouse

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

    2003-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

    It is well recognized that seabirds, particularly those nesting in coastal colonies, can provide significant nutrient enrichment to Arctic terrestrial ecosystems. However, little is known about the fate of bird-derived nutrients that return to the marine environment and potentially concentrate below the colonies. To attempt to assess the influence of this potential nutrient enrichment of the coastal benthic community, samples of macroalgae, sea urchins (mainly algivores), and hermit crabs (scavengers) were collected at two Arctic localities (Spitsbergen), (1) below a mixed colony of guillemots and kittiwakes, and (2) in an adjacent geomorphologically similar location not influenced by the seabird colony. A much higher nitrogen stable isotope ratio (?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.

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

    Microsoft Academic Search

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

    2009-01-01

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

  10. Shallow benthic fauna communities of South Georgia Island

    Microsoft Academic Search

    David K. A. Barnes; Katrin Linse; Cath Waller; Simon Morely; Peter Enderlein; Keiron P. P. Fraser; Matt Brown

    2006-01-01

    Benthic communities in several fjords and sheltered bays of the north coast of South Georgia Island were examined using SCUBA\\u000a and shore sampling in November 2004. It is one of the most northerly islands within the Polar Front and its well studied,\\u000a terrestrial biota is described as sub Antarctic. The intertidal and subtidal zones and their fauna are, by comparison,

  11. Reproductive periodicities of some benthic algae in lower Chesapeake Bay

    Microsoft Academic Search

    Jacques S. Zaneveld; William D. Barnes

    1965-01-01

    Semi-monthly (monthly in winter) studies of the reproductive cycles of 8 benthic Chlorophyta, 3 Phaeophyta, and 18 Rhodophyta\\u000a were carried out over a period of three years at three different localities in the lower Chesapeake Bay. Of the 29 species\\u000a studied, 11 are perennial, 6 occur in three seasons, 7 in two seasons, and 5 in one season only.\\u000a \\u000a The

  12. In situ measurement of odor compound production by benthic cyanobacteria.

    PubMed

    Chen, Yan-Min; Hobson, Peter; Burch, Michael D; Lin, Tsair-Fuh

    2010-03-01

    A simple technique was developed to make in situ measurements of emission rates of two common odorants, 2-MIB and geosmin, and was validated with different natural communities of benthic cyanobacterial mats in Hope Valley Reservoir (HVR), South Australia, and Kin-Men Water Treatment Plant (TLR-WTP), Taiwan. A pair of parallel columns was used to differentiate between emission and loss rates caused by biodegradation, volatilization, and other mechanisms. Experimental results indicated that the loss rates followed a first-order relationship for all cases tested, with biodegradation and volatilization being the key mechanisms. The loss rates were comparable to those reported in the literature for biodegradation and those calculated from two-film theory for volatilization. After accounting for the loss rates, the net emission of geosmin and 2-MIB was estimated from experimental data. Odorant emission rates on the basis of column surface area, cyanobacterial cell number, and chlorophyll a (chl-a) were 4.2-4.4 ng h(-1) cm(-2), 1.0-5.5 x 10(-6) ng h(-1) cell(-1), and 3.2-3.5 ng h(-1)microg-chl(-1), respectively for 2-MIB released from benthic mats in TLR-WTP, and, 18-190 ng h(-1) cm(-2), 0.053-1.8 x 10(-3) ng h(-1) cell(-1), and 48-435 ng h(-1)microg-chl(-1) respectively for geosmin from benthic mats in HVR. The method developed provides a simple means to estimate the emission rates of odorants and possibly other algal metabolites from benthic cyanobacterial mats. PMID:20445867

  13. Prey capture by a benthic coral reef hydrozoan

    Microsoft Academic Search

    R. Coma; M. Ribes; C. Orejas; J.-M. Gili

    1999-01-01

    The natural diet and prey abundance of the benthic coral reef hydrozoan Nemalecium lighti, a common tropical species, were studied by analysing the gastrovascular contents of polyps. Prey capture was estimated from\\u000a 10 samples collected at 3-h intervals during a single diel cycle (1–2 September, 1995) in the San Blas Islands (Panamá). Prey\\u000a size ranged from 5 to 550??m, with

  14. Vulnerability of benthic habitats to the aquatic invasive species

    Microsoft Academic Search

    Anastasija Zaiko; Sergej Olenin; Darius Daunys; Tomas Nalepa

    2007-01-01

    A comparative vulnerability analysis of 16 selected benthic habitat types in the SE Baltic Sea waters and the Curonian lagoon,\\u000a including Klaipeda strait, was performed using long-term monitoring datasets (1980–2003) and results of several other surveys\\u000a in the lagoon and the sea. Results indicated that invasive species richness (number of alien species per habitat) in lagoon\\u000a habitats was significantly higher

  15. Benthic macroinvertebrates associated with four species of macrophytes

    Microsoft Academic Search

    Irella Bogut; Jasna Vidakovi?; Goran Palijan; Dubravka ?erba

    2007-01-01

    Benthic macroinvertebrates associated with four species of macrophytes (Nymphoides peltata, Ceratophyllum demersum, Polygonum amphibium and Carex sp.) were investigated during two growing seasons (2001 and 2002) in the slow-flowing ?onakut Channel in the Kopa?ki rit\\u000a Nature Park in Croatia. A total of 31 macroinvertebrate taxa were found. C. demersum, a submerged plant with dissected leaves, supported the highest macroinvertebrate abundance,

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

    USGS Publications Warehouse

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

    1996-01-01

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

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

    USGS Publications Warehouse

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

    1996-01-01

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

  18. Improved oxygen isotope temperature calibrations for cosmopolitan benthic foraminifera

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

    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.

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

    PubMed

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

    2011-08-01

    Benthic biofilters were deployed under a cage fish farm and in two reference locations to assess the influence of the farm on the biofilters and the surroundings, as well as to verify the usefulness of this technology as a mitigation tool. The biofilters underneath the farm recruited a fouling community practically identical to that of the control biofilters, which included a variety of trophic strategies. The former showed a higher 15N enrichment, indicating that fouling beneath the farm was benefiting from the farm waste. The waste retention efficiency was low (0.02 g N m(-2) month(-1)) beneath the farm. Benthic biofilters aggregated demersal wild fish around and within them. Pelagic wild fish also frequently used the biofilters beneath the farm, forming compact shoals around them. The increased complexity of the habitat below the fish farm enhanced biodiversity, but this improvement did not lead to the recovery of the sediments around the biofilters. PMID:21669446

  20. Predictive models of benthic invertebrate methylmercury in Ontario and Quebec lakes

    Microsoft Academic Search

    M. D. Rennie; N. C. Collins; C. F. Purchase; A. Tremblay

    2005-01-01

    Multivariate analyses on benthic invertebrate methylmercury concentrations ((MeHg)) and water chemistry from 12 Quebec water bodies were used to guide the construction of simple, predictive models of benthic invertebrate (MeHg) in 23 lakes in Ontario and Quebec. Separate predictive models for collector-shredder and predatory benthic invertebrates were constructed using multiple regression and were assessed for their predictive utility by cross-

  1. Benthic production and processes off Baja California, northwest Africa and Peru: a classification of benthic subsystems in upwelling ecosystems

    SciTech Connect

    Rowe, G.T.

    1983-01-01

    Estimates of the standing stocks, secondary production and metabolism of the benthos have been compared in the coastal upwelling ecosystems off northwest Africa, Baja California, and southern Peru. Northwest Africa is characterized by shelf break upwelling and as a result standing stocks, macrobenthic production and sediment organic matter are highest out at the shelf-slope boundary. Sediment microbial activity and biomass on the other hand are highest nearshore in the dynamic zone where aeolian silt and sand are being blown into the sea from the Sahara Desert. Baja California is dominated by the red crab, Pleuroncodes planipes, having high rates of growth and metabolic utilization of organic matter, both on bottom and in the water. Peru benthos and metabolism are very different from the above areas because of the low oxygen concentrations in the bottom water. Organic matter is far higher in the sediment and heterotrophic metabolism is principally anaerobic rather than aerobic. A normal offshore benthic fauna is replaced by a mat of sulfur bacteria with unknown production and metabolic rates. Benthic subsystems in upwelling ecosystems can be placed in two categories: those overloaded with organic matter, depleted of oxygen and dominated by sulfate reduction and those that are not overloaded and remain aerobic. Peru and southwest Africa typify overloaded systems whereas NW Africa and Baja California are examples of aerobic systems. Although benthic metabolism and ionorganic nutrient regeneration are high in both types of subsystems, all upwelling ecosystems, with their dynamic open boundaries, export organic particulate matter and import inorganic nutrients at rates that are far in excess of that consumed or produced by benthic metabolism. 42 refs., 7 figs., 8 tabs.

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

    USGS Publications Warehouse

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

    2010-01-01

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

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

    E-print Network

    Smith, Jennifer E.

    States of America Abstract Benthic primary producers in marine ecosystems may significantly alter remineralization in the lagoonal reefs of Moorea, French Polynesia. Rates of photosynthesis, respiration

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

    EPA Science Inventory

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

  5. A Servicewide Benthic Mapping Program for National Parks

    USGS Publications Warehouse

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

    2010-01-01

    In 2007, the National Park Service (NPS) Inventory and Monitoring Program directed the initiation of a benthic habitat mapping program in ocean and coastal parks in alignment with the NPS Ocean Park Stewardship 2007-2008 Action Plan. With 74 ocean and Great Lakes parks stretching over more than 5,000 miles of coastline across 26 States and territories, this Servicewide Benthic Mapping Program (SBMP) is essential. This program will deliver benthic habitat maps and their associated inventory reports to NPS managers in a consistent, servicewide format to support informed management and protection of 3 million acres of submerged National Park System natural and cultural resources. The NPS and the U.S. Geological Survey (USGS) convened a workshop June 3-5, 2008, in Lakewood, Colo., to discuss the goals and develop the design of the NPS SBMP with an assembly of experts (Moses and others, 2010) who identified park needs and suggested best practices for inventory and mapping of bathymetry, benthic cover, geology, geomorphology, and some water-column properties. The recommended SBMP protocols include servicewide standards (such as gap analysis, minimum accuracy, final products) as well as standards that can be adapted to fit network and park unit needs (for example, minimum mapping unit, mapping priorities). SBMP Mapping Process. The SBMP calls for a multi-step mapping process for each park, beginning with a gap assessment and data mining to determine data resources and needs. An interagency announcement of intent to acquire new data will provide opportunities to leverage partnerships. Prior to new data acquisition, all involved parties should be included in a scoping meeting held at network scale. Data collection will be followed by processing and interpretation, and finally expert review and publication. After publication, all digital materials will be archived in a common format. SBMP Classification Scheme. The SBMP will map using the Coastal and Marine Ecological Classification Standard (CMECS) that is being modified to include all NPS needs, such as lacustrine ecosystems and submerged cultural resources. CMECS Version III (Madden and others, 2010) includes components for water column, biotic cover, surface geology, sub-benthic, and geoform. SBMP Data Archiving. The SBMP calls for the storage of all raw data and final products in common-use data formats. The concept of 'collect once, use often' is essential to efficient use of mapping resources. Data should also be shared with other agencies and the public through various digital clearing houses, such as Geospatial One-Stop (http://gos2.geodata.gov/wps/portal/gos). To be most useful for managing submerged resources, the SBMP advocates the inventory and mapping of the five components of marine ecosystems: surface geology, biotic cover, geoform, sub-benthic, and water column. A complete benthic inventory of a park would include maps of bathymetry and the five components of CMECS. The completion of mapping for any set of components, such as bathymetry and surface geology, or a particular theme (for example, submerged aquatic vegetation) should also include a printed report.

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

    NASA Astrophysics Data System (ADS)

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

    2009-12-01

    Paleoceanographic conditions in the Japan Sea changed drastically during the late Quaternary in association with orbital and suborbital cycles and glacio-eustatic sea level changes. However, few studies had been examined long-term sediment records older than last intergracial period because of the lack of long cores which contains continuous paleoclimatic records and difficulties reconstructing high-resolution age models. Especially disappearance of benthic foraminifers by euxinic bottom water conditions during glacial maxima makes it difficult to understand specific bottom water environments. In this study, we reconstructed benthic foraminiferal stable isotopic stratigraphy of the Japan Sea core with the resolution in 2 kyr. and compared the global stack of benthic foraminfieral ?18O curve (LR04, Lisiecki & Raymo, 2005). The investigated core MD01-2408, was recovered from 806 m water depth, off Akita Prefecture during IMAGES VII cruise. It had recorded continuous paleoenvironmental histories during the last 230 kyr through the core. This core was mainly consisted of alternating layers of homogeneous light colored silty clay and laminated or bioturbated dark colored silty clay, occasionally intercalating volcanic ash layers. The most abundant benthic foraminiferal species are Uvigerina akitaensis, Angulogerina kokozuraensis and Islandiella norcrossi. Abundance of these species fluctuated drastically through the core. No benthic foraminifera is found in two dark layer intervals 4 ~ 5 mbsf and 25 ~ 25.5 mbsf, corresponding 15 ~ 25 kyr and 149 ~ 152 kyr, respectively, probably representing super anoxic bottom water conditions(Oba et al 1984 1991;Tada et al., 1999). ?18O of U. akitaensis and A. kokozuraensis showed a similar values with a precision of ± 0.27‰ and it was inferred that both species had similar habitat. ?18O of both species in core MD01-2408 fluctuated with the range of 2‰ over 230 kyr. Although benthic ?18O stack of LR04 reached to 5 ‰ during the glacial maxima, ?18O of core MD01-2408 were 2.6 ‰ and 2.7 ‰ during MIS 2a and MIS 6, respectively. Differences of bottom water ?18O between global average and the Japan Sea were 2.3 ~ 2.4 ‰. This reason of negative excursions was considered as downward diffusion of low saline surface water to the bottom (Oba et al 1984 1991). However, the interglacial stages during MIS3 to 5, benthic foraminiferal ?18O was rather heavier (4.0 ~ 4.5‰) than MIS2 and 6. Furthermore, benthic ?18O values had became ligher from MIS5a to 2 gradually. These ?18O shift should be attributed to bottom water salinity change rather than temperature. It is considered that the thickness of less saline surface water had increased and strongly affected to the bottom water properties in the glacial maximum stages through the last 230 kyr.

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

    PubMed Central

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

    2015-01-01

    Sediment cores were collected from three sites (1000–1200 m water depth) in the northeastern Gulf of Mexico from December 2010 to June 2011 to assess changes in benthic foraminiferal density related to the Deepwater Horizon (DWH) event (April-July 2010, 1500 m water depth). Short-lived radioisotope geochronologies (210Pb, 234Th), organic geochemical assessments, and redox metal concentrations were determined to relate changes in sediment accumulation rate, contamination, and redox conditions with benthic foraminiferal density. Cores collected in December 2010 indicated a decline in density (80–93%). This decline was characterized by a decrease in benthic foraminiferal density and benthic foraminiferal accumulation rate (BFAR) in the surface 10 mm relative to the down-core mean in all benthic foraminifera, including the dominant genera (Bulimina spp., Uvigerina spp., and Cibicidoides spp.). Cores collected in February 2011 documented a site-specific response. There was evidence of a recovery in the benthic foraminiferal density and BFAR at the site closest to the wellhead (45 NM, NE). However, the site farther afield (60 NM, NE) recorded a continued decline in benthic foraminiferal density and BFAR down to near-zero values. This decline in benthic foraminiferal density occurred simultaneously with abrupt increases in sedimentary accumulation rates, polycyclic aromatic hydrocarbon (PAH) concentrations, and changes in redox conditions. Persistent reducing conditions (as many as 10 months after the event) in the surface of these core records were a possible cause of the decline. Another possible cause was the increase (2–3 times background) in PAH’s, which are known to cause benthic foraminifera mortality and inhibit reproduction. Records of benthic foraminiferal density coupled with short-lived radionuclide geochronology and organic geochemistry were effective in quantifying the benthic response and will continue to be a valuable tool in determining the long-term effects of the DWH event on a larger spatial scale. PMID:25785988

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

    PubMed

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

    2015-03-01

    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 0.5 cm) 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 0.309 d(-1))>treatment B (0.460 and 0.256 d(-1))>treatment A (0.216 and 0.039 d(-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 0.165 d(-1) in treatment BA, 0.329 and 0.194 d(-1) in treatment B, 0.129 d(-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

  9. 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...

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

    E-print Network

    Vallino, Joseph J.

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

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

    PubMed

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

    2010-02-01

    Worldwide, many marine coastal habitats are facing rapid deterioration due in part to human-driven changes in habitat characteristics, including changes in flow patterns, a factor known to greatly affect primary production in corals, algae, and seagrasses. The effect of flow traditionally is attributed to enhanced influx of nutrients and dissolved inorganic carbon (DIC) across the benthic boundary layer from the water to the organism however, here we report that the organism's photosynthetic response to changes in the flow is nearly instantaneous, and that neither nutrients nor DIC limits this rapid response. Using microelectrodes, dual-pulse amplitude-modulated fluorometry, particle image velocimetry, and real time mass-spectrometry with the common scleractinian coral Favia veroni, the alga Gracilaria cornea, and the seagrass Halophila stipulacea, we show that this augmented photosynthesis is due to flow-driven enhancement of oxygen efflux from the organism to the water, which increases the affinity of the RuBisCO to CO(2). No augmentation of photosynthesis was found in the absence of flow or when flow occurred, but the ambient concentration of oxygen was artificially elevated. We suggest that water motion should be considered a fundamental factor, equivalent to light and nutrients, in determining photosynthesis rates in marine benthic autotrophs. PMID:20133799

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

    PubMed Central

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

    2010-01-01

    Worldwide, many marine coastal habitats are facing rapid deterioration due in part to human-driven changes in habitat characteristics, including changes in flow patterns, a factor known to greatly affect primary production in corals, algae, and seagrasses. The effect of flow traditionally is attributed to enhanced influx of nutrients and dissolved inorganic carbon (DIC) across the benthic boundary layer from the water to the organism however, here we report that the organism’s photosynthetic response to changes in the flow is nearly instantaneous, and that neither nutrients nor DIC limits this rapid response. Using microelectrodes, dual-pulse amplitude-modulated fluorometry, particle image velocimetry, and real time mass-spectrometry with the common scleractinian coral Favia veroni, the alga Gracilaria cornea, and the seagrass Halophila stipulacea, we show that this augmented photosynthesis is due to flow-driven enhancement of oxygen efflux from the organism to the water, which increases the affinity of the RuBisCO to CO2. No augmentation of photosynthesis was found in the absence of flow or when flow occurred, but the ambient concentration of oxygen was artificially elevated. We suggest that water motion should be considered a fundamental factor, equivalent to light and nutrients, in determining photosynthesis rates in marine benthic autotrophs. PMID:20133799

  13. Low virus to prokaryote ratios in the cold: benthic viruses and prokaryotes in a subpolar marine ecosystem (Hornsund, Svalbard).

    PubMed

    Wróbel, Borys; Filippini, Manuela; Piwowarczyk, Joanna; Kedra, Monika; Kuli?ski, Karol; Middelboe, Mathias

    2013-03-01

    The density and spatial distribution of benthic viruses and prokaryotes in relation to biotic and abiotic factors were investigated in sediment cores collected in Hornsund, a permanently cold fjord on the West coast of Svalbard, Norway. The cores were obtained from the mouth of the fjord to the central basin, along a longitudinal transect. The results of our analyses showed lower densities of viruses (0.2 x 10(8) to 5.4 x 10(8) virus-like particles/g) and lower virus-to-prokaryote ratios (0.2-0.6, with the exception of the uppermost layer in the central basin, where the ratio was about 1.2) at the study site than generally found in the temperate areas, despite the relatively high organic matter content in subpolar sediments. Variations in benthic viral and prokaryote abundances along gradients of particle sedimentation rates, phytopigment concentrations, and macrobenthic species composition together suggested the influence of particle sedimentation and macrobenthic bioturbation on the abundance and spatial distribution ofprokaryotes and viruses in cold habitats. PMID:24151781

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

    NASA Astrophysics Data System (ADS)

    Thomas, E.

    2007-12-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

  16. Dispersal, survival and delayed growth of benthic foraminiferal propagules

    NASA Astrophysics Data System (ADS)

    Alve, Elisabeth; Goldstein, Susan T.

    2010-01-01

    New data support our previously published propagule dispersal hypothesis and show that propagules of some benthic foraminiferal species can survive for two years before growth commences. Following exposure to simulated shallow-water conditions, shallow-water species of benthic foraminifera appeared and grew in large numbers (commonly >100 ind/12 ml sediment) in the <32 µm-size sediment fraction collected from 320 m water depth in the Skagerrak basin (North Sea). None of the shallow-water species that grew abundantly ( Planorbulina mediterranensis, Morulaeplecta bulbosa, Bolivina pseudoplicata, Cuneata arctica, Eggerelloides scaber, Gavelinopsis praegeri) seem to grow or reproduce at or in the vicinity of the sampling site. Consequently, they must have been transported there as <32 µm-sized individuals. Their sudden appearance when exposed to shallow-water conditions suggests that they had been transported to the sampling site as propagules and that they could survive in the sediments until conditions became suitable for growth and, for some, reproduction. The lack of agglutination on the proloculi of the agglutinated taxa that appeared in the growth-chambers may enhance their passive transport via currents and, thereby, dispersal. Of all the indigenous foraminiferal species that occur at the sampling site, only Textularia earlandi and Bolivinellina pseudopunctata continued to grow and reproduce when transferred from bathyal (320 m) to simulated shallow-water (0 m) conditions. The former is considered a highly opportunistic species. According to the literature, most of the morphospecies which grew in the experiments are cosmopolitan. Our results indicate substantial inter-specific differences in dispersal potential and support previous suggestions that among free-living species, some serial forms have the potential for long-distance dispersal. Still, oceanographic, physical and ecological boundaries and barriers constrain the distribution of most species. In addition to benthic foraminifera, Gromia spp. (rhizarian protists related to the foraminifera) grew in >60% of the experimental growth-chambers.

  17. Disturbance, colonization and development of Antarctic benthic communities

    PubMed Central

    Barnes, David K.A; Conlan, Kathleen E

    2006-01-01

    A decade has yielded much progress in understanding polar disturbance and community recovery—mainly through quantifying ice scour rates, other disturbance levels, larval abundance and diversity, colonization rates and response of benthos to predicted climate change. The continental shelf around Antarctica is clearly subject to massive disturbance, but remarkably across so many scales. In summer, millions of icebergs from sizes smaller than cars to larger than countries ground out and gouge the sea floor and crush the benthic communities there, while the highest wind speeds create the highest waves to pound the coast. In winter, the calm associated with the sea surface freezing creates the clearest marine water in the world. But in winter, an ice foot encases coastal life and anchor ice rips benthos from the sea floor. Over tens and hundreds of thousands of years, glaciations have done the same on continental scales—ice sheets have bulldozed the seabed and the zoobenthos to edge of shelves. We detail and rank modern disturbance levels (from most to least): ice; asteroid impacts; sediment instability; wind/wave action; pollution; UV irradiation; volcanism; trawling; non-indigenous species; freshwater inundation; and temperature stress. Benthic organisms have had to recolonize local scourings and continental shelves repeatedly, yet a decade of studies have demonstrated that they have (compared with lower latitudes) slow tempos of reproduction, colonization and growth. Despite massive disturbance levels and slow recolonization potential, the Antarctic shelf has a much richer fauna than would be expected for its area. Now, West Antarctica is among the fastest warming regions and its organisms face new rapid changes. In the next century, temperature stress and non-indigenous species will drastically rise to become dominant disturbances to the Antarctic life. Here, we describe the potential for benthic organisms to respond to disturbance, focusing particularly on what we know now that we did not a decade ago. PMID:17405206

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

    NASA Astrophysics Data System (ADS)

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

    2013-07-01

    Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (NCP) and calcification (NCC). Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to changes in the seawater aragonite saturation state (?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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-02-01

    Ocean acidification is a threat to marine ecosystems globally. In shallow-water systems, however, ocean acidification can be masked by benthic carbon fluxes, depending on community composition, seawater residence time, and the magnitude and balance of net community production (pn) and calcification (gn). Here, we examine how six benthic groups from a coral reef environment on Heron Reef (Great Barrier Reef, Australia) contribute to changes in seawater aragonite saturation state (?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.

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

    PubMed

    Barnes, David K A; Conlan, Kathleen E

    2007-01-29

    A decade has yielded much progress in understanding polar disturbance and community recovery-mainly through quantifying ice scour rates, other disturbance levels, larval abundance and diversity, colonization rates and response of benthos to predicted climate change. The continental shelf around Antarctica is clearly subject to massive disturbance, but remarkably across so many scales. In summer, millions of icebergs from sizes smaller than cars to larger than countries ground out and gouge the sea floor and crush the benthic communities there, while the highest wind speeds create the highest waves to pound the coast. In winter, the calm associated with the sea surface freezing creates the clearest marine water in the world. But in winter, an ice foot encases coastal life and anchor ice rips benthos from the sea floor. Over tens and hundreds of thousands of years, glaciations have done the same on continental scales-ice sheets have bulldozed the seabed and the zoobenthos to edge of shelves. We detail and rank modern disturbance levels (from most to least): ice; asteroid impacts; sediment instability; wind/wave action; pollution; UV irradiation; volcanism; trawling; non-indigenous species; freshwater inundation; and temperature stress. Benthic organisms have had to recolonize local scourings and continental shelves repeatedly, yet a decade of studies have demonstrated that they have (compared with lower latitudes) slow tempos of reproduction, colonization and growth. Despite massive disturbance levels and slow recolonization potential, the Antarctic shelf has a much richer fauna than would be expected for its area. Now, West Antarctica is among the fastest warming regions and its organisms face new rapid changes. In the next century, temperature stress and non-indigenous species will drastically rise to become dominant disturbances to the Antarctic life. Here, we describe the potential for benthic organisms to respond to disturbance, focusing particularly on what we know now that we did not a decade ago. PMID:17405206

  1. Larger benthic foraminifera of the Paleogene Promina Beds (Croatia)

    NASA Astrophysics Data System (ADS)

    Cosovic, V.; Mrinjek, E.; Drobne, K.

    2012-04-01

    In order to add more information about complex origin of Promina Beds (traditionally interpreted as Paleogene molasse of Dinarides), two sections (Lišani Ostrova?ki and Ostrovica, Central Dalmatia, Croatia) have been studied in detail. Sampled carbonate sequences contain predominantly coralline red algae, larger benthic foraminifera and corals. Based on sedimentary textures, nummulitid (Nummulites s.str and Asterigerina sp.) test shapes and the associated skeletal components, altogether three types of the Middle Eocene (Lutetian to Bartonian) facies were recognized. The Ostrovica section is composed of alternating couples of marly limestones and marls, several decimeters thick with great lateral continuity. Two facies which vertically alternate are recognized as Nummulites - Asterigerina facies, where patchily dispersed large, robust and party reworked larger benthic foraminifera constitute 20% and small bioclasts (fomaniniferal fragments and whole tests less than 3 mm in diameters) 10% of rock volume and, Coral - Red algal facies with coral fragments of solitary and colonial taxa up to 1 cm in size constitute 5 - 40%, red algae 15 - 60% and lager benthic foraminifera up to 5% of rock volume. The textural and compositional differences among the facies suggest rhythmic exchanges of conditions that characterize shallower part of the mesophotic zone with abundant nummulithoclasts with deeper mesophotic, lime mud-dominated settings where nummulitids with the flat tests, coralline red algae and scleractinian corals are common. The scleractinian corals (comprising up to 20% of rock volume) encrusted by foraminifera (Acervulina, Haddonia and nubeculariids) or coralline red algae and foraminiferal assemblage made of orthophragminid and nummulitid tests scattered in matrix, are distributed uniformly throughout the studied Lišani Ostrova?ki section. In the central part of section, wavy to smooth thin (< 1 mm) crusts (laminas) alternating with encrusted corals occur. The characteristics of associated fauna and spatial relationship between corals and laminations indicate that this facies originated in a mid-ramp (shelf) setting.

  2. 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.

  3. Benthic foraminifers: proxies or problems?. A review of paleocological concepts

    NASA Astrophysics Data System (ADS)

    Van der Zwaan, G. J.; Duijnstee, I. A. P.; den Dulk, M.; Ernst, S. R.; Jannink, N. T.; Kouwenhoven, T. J.

    1999-05-01

    In this paper, we review benthic foraminiferal distribution patterns in the context of their use as proxy to reconstruct paleoenvironments, in particular against the background of relevant biological data. These data suggest that benthic foraminifera, as most microbiota, are not stenotopic to most environmental variables. A more generalist strategy seems beneficial since the low degree of specialisation prevents rapid extinction. This immediately suggests that parameters like temperature and salinity are not very important in benthic foraminiferal distribution and thus not in proxy studies. Oxygen and organic flux, on the other hand, are of great ecological importance and it is not surprising that all viable proxies today are based on relationships with these parameters. Organic flux (food) is important in deciding on abundance, but is subordinate as soon as oxygen starts to be limiting. This is the case in almost all shallow water systems with muddy substrates, sometimes down to considerable waterdepth. Microhabitat patterns are shaped through the arrangement of species along a redox gradient, whereby species distribution seems to be correlated with specific redox levels. It cannot be excluded that a relationship with specific bacterial suites also plays a role here. However, the coupling to the successive redox stages provides a means for very detailed reconstructions of oxygenation. On the other hand, organic flux reconstructions can be distorted due to the fact that the same flux levels, though with different oxygenation, are characterised by different suites of species. Therefore, assemblage characteristics are discussed as additional means to constrain organic flux reconstructions. It is concluded that species distribution with depth is mainly a function of organic flux and oxygenation. In this sense, paleobathymetry should not be based on individual marker species, but preferably on quantitative assemblage characteristics such as P/ B ratios. However, more generalised schemes of assemblage successions with depth are clearly helpful. It is further concluded that benthic foraminiferal distribution, and microhabitat occupation, are regulated by the interplay of organic flux, oxygen and competition. Each of these factors is acting in a different way and leads to the complex pattern as found in living associations.

  4. 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...

  5. DEVELOPING AND INDEX OF BENTHIC CONDITION FOR THE ACADIAN BIOGEOGRAPHIC PROVINCE

    EPA Science Inventory

    The National Coastal Assessment has sampled benthic assemblages each summer since 2000 in coastal areas of the U.S. Acadian Biogeographic Province (tip of Cape Cod to Canadian border). We are developing a multimetric index to be used as an indicator of benthic condition. During...

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

    Microsoft Academic Search

    Paul J. Godfrey

    1978-01-01

    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

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

    Microsoft Academic Search

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

    2001-01-01

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

  8. Efficiencies of benthic and pelagic trophic pathways in a subalpine lake

    Microsoft Academic Search

    M. Jake Vander Zanden; Sudeep Chandra; Sang-Kyu Park; Yvonne Vadeboncoeur; Charles R. Goldman

    2006-01-01

    Although the study of lakes has traditionally focused on pelagic production pathways, recent stable isotope and diet evidence indicates that benthic algal production is an important contributor to fish production. This has led to the suggestion that energy may be more efficiently passed along benthic food chains relative to their pelagic counter- parts. To test this idea, we combined stable

  9. Monitoring of oxygenic and anoxygenic photosynthesis in a unicyanobacterial biofilm, grown in benthic gradient chamber

    Microsoft Academic Search

    Olivier Pringault; Ferran Garcia-Pichel

    2000-01-01

    In order to assess the role of cyanobacteria in the formation and dynamics of microenvironments in microbial mats, we studied an experimental biofilm of a benthic, halotolerant strain, belonging to the Halothece cluster of cyanobacteria. The 12-week-old biofilm developed in a sand core incubated in a benthic gradient chamber under opposing oxygen and sulfide vertical concentration gradients. At the biofilm

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

    EPA Science Inventory

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

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

    E-print Network

    Rasmussen, Joseph

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

  12. 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...

  13. Fish Reliance on LittoralBenthic Resources and the Distribution of

    E-print Network

    Vander Zanden, Jake

    focused on pelagic (open-water) production and processes. We com- piled carbon stable isotope data from, benthic algae com- prised 36% of whole-lake primary production (BPf = 0.36). BPf and BRL were weakly correlated: BRL tends to be high even in large/deep lakes in which benthic algae is a minor contributor

  14. 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...

  15. Tools for the development of a benthic quality index for Italian lakes

    Microsoft Academic Search

    Bruno ROSSARO; Angela BOGGERO; Valeria LENCIONI; Laura MARZIALI; Angelo SOLIMINI

    2006-01-01

    In this paper, we propose a methodology to develop a benthic quality index useful for Italian lakes. The existing data about benthic macroinvertebrates of the Italian lakes were collected over a period of 50 years, but only a few lakes such as the Maggiore and the Mergozzo have been intensely studied. Some large lakes such as Lake Como are still

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

    Microsoft Academic Search

    Keith B. Gido

    2002-01-01

    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

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

    EPA Science Inventory

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

  18. Continued disappearance of the benthic amphipod Diporeia spp. in Lake Michigan: is there evidence

    E-print Network

    Continued disappearance of the benthic amphipod Diporeia spp. in Lake Michigan: is there evidence in densities of the benthic amphipod Diporeia spp. and dreissenid mussels. In the southern basin, Diporeia changements récents de densité de l'amphipode benthique Diporeia spp. et des bivalves dreissénidés. Dans le

  19. Impacts of sedimentation on soft-bottom benthic communities in the southern islands of Singapore

    Microsoft Academic Search

    L. M. Chou; J. Y. Yu; T. L. Loh

    2004-01-01

    Benthic community data from eight stations around Pulau Semakau, an island south of Singapore, were collected during three surveys and analysed to determine changes in community structure under different sediment regimes resulting from construction activity at the eastern part of Pulau Semakau. Multidimensional Scaling (MDS) Configurations indicated distinct changes in the abundance, family number and diversity of benthic invertebrate fauna,

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

    E-print Network

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

  1. 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...

  2. Ecological responses to simulated benthic-derived nutrient subsidies mediated by omnivorous fish

    Microsoft Academic Search

    STEPHEN P. GLAHOLT JR; MICHAEL J. VANNI

    2005-01-01

    SUMMARY 1. Fish can play an important role in coupling benthic and pelagic habitats by consuming benthic prey and providing essential nutrients to algae in dissolved form. However, little is known about the factors affecting the magnitude of this nutrient subsidy. 2. Using laboratory and mesocosm experiments we evaluated how varying ingestion rates of bluegill sunfish (Lepomis macrochirus) affects fish

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

    Microsoft Academic Search

    Vincent H. Resh; Donald G. Price

    1984-01-01

    Sequential sampling is a method for monitoring benthic macroinvertebrates that can significantly reduce the number of samples required to reach a decision, and consequently, decrease the cost of benthic sampling in environmental impact assessments. Rather than depending on a fixed number of samples, this analysis cumulatively compares measured parameter values (for example, density, community diversity) from individual samples, with thresholds

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

    E-print Network

    Jackson, Don

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

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

    Microsoft Academic Search

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

    2002-01-01

    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

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

    EPA Science Inventory

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

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

    E-print Network

    Luther, Douglas S.

    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

  8. Benthic extinction and recovery patterns at the K\\/T boundary in shallow water carbonates, Denmark

    Microsoft Academic Search

    Eckart Håkansson; Erik Thomsen

    1999-01-01

    Benthic extinction at the K\\/T boundary in the Danish Basin is abrupt and indistinguishable from the termination of Maastrichtian White Chalk deposition. The Danian benthic fauna — already fully established in the earliest Danian nannoplankton zone NP1 — is essentially an impoverished Maastrichtian fauna established through direct survival or limited evolution within well-established clades, already present in the Maastrichtian of

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

    EPA Science Inventory

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

  10. The invertebrate benthic community of two solar salt ponds in Aveiro, Portugal

    Microsoft Academic Search

    N. Vieira; F. Amat

    1996-01-01

    The invertebrate benthic community of two Aveiro salt pond systems was studied in order to evaluate its diversity, density and the influence of organic matter and salt production. Samples were collected monthly at Esmolas and Tanoeiras. Five groups of benthic organisms were found: Nemathelminthes, Annelida (Nereis diversicolor), Crustacea (Sphaeroma serratum andTanais cavolini), Insecta (Chironomidae), Bivalvia Mollusca (Cerastoderma edule, Spisula solida

  11. 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...

  12. 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...

  13. 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...

  14. 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

  15. EXPOSURE TO SUDDEN LIGHT BURST AFTER PROLONGED DARKNESS—A CASE STUDY ON BENTHIC DIATOMS IN ANTARCTICA

    Microsoft Academic Search

    Angela Wulff; Michael Y. Roleda; Katharina Zacher; Christian Wiencke

    2008-01-01

    In polar areas, benthic diatoms are regarded to play a major role in supplying energy to the benthic fauna, particularly prior to the release of microalgae from sea ice and the phytoplankton bloom. As phototrophs, benthic polar diatoms have to contend not only with dark polar nights but also with darkness due to sea-ice and snow cover that can prevail

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

    E-print Network

    deYoung, Brad

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

  17. Seasonal enhancement of submarine groundwater discharge (SGD)-derived nitrate loading into the Ria Formosa coastal lagoon assessed by 1-D modeling of benthic NO3- profiles

    NASA Astrophysics Data System (ADS)

    Ibánhez, J. Severino P.; Leote, Catarina; Rocha, Carlos

    2013-11-01

    The role of benthic sandy ecosystems in mitigating NO3- loads carried by Submarine Groundwater Discharge (SGD) to coastal marine ecosystems is uncertain. Benthic biogeochemical mediation of NO3--rich submarine groundwater discharge was studied at the seepage face of a barrier island site in the Ria Formosa coastal lagoon (Southern Portugal). Preliminary analysis of NO3- porewater distributions at the seepage face during discharge indicated that benthic biogeochemical processes could significantly affect the fluxes of groundwater-borne NO3- into the lagoon. In order to discriminate between the relative contribution of transport and reaction processes to shape and concentration range evidenced by in-situ porewater NO3- gradients, an advection-dispersion-reaction (ADR) model of NO3- diagenesis was applied to describe NO3- porewater profiles obtained in March, June, September and December 2006. Good agreement between modeled and measured profiles was obtained. Model-derived apparent benthic nitrification and NO3- reduction rates ranged from 0.01 to 5.2 mmol m-2 h-1, sufficient to explain gross observed changes in NO3- fluxes arriving at the seepage face (up to 70% within the surficial 20 cm depth layer). Results of the analysis indicated that the upper limit of the seepage face promoted mitigation of NO3- fluxes to the lagoon throughout the year. In contrast, the lower limit of the seepage area promoted net amplification of the NO3- fluxes into the lagoon in June and September. These results will help constrain further work aiming to clarify the role of permeable sediments in mitigating nitrogen loading of coastal ecosystems.

  18. Benthic foraminiferal response to trace element pollution-the case study of the Gulf of Milazzo, NE Sicily (Central Mediterranean Sea).

    PubMed

    Cosentino, Claudia; Pepe, Fabrizio; Scopelliti, Giovanna; Calabrò, Monica; Caruso, Antonio

    2013-10-01

    The response of benthic foraminiferal assemblages to trace element pollution in the marine sediments of the Gulf of Milazzo (north-eastern Sicily) was investigated. Since the 1960s, this coastal area has been a preferred site for the development of two small marinas and a commercial harbour as well as for heavy industry. Forty samples collected in the uppermost 3-4 cm of an undisturbed layer of sediment in the littoral environment were used for this benthic foraminiferal analysis. The enrichment factors (EFs) of selected trace elements (As, Co, Cr, Cu, Mn, Ni, Pb and Zn) were also calculated. Changes both in benthic foraminiferal assemblages and in some trace elements concentrations have provided evidence that the gulf's littoral zone can be subdivided into three sectors characterised by environmental changes in the marine ecosystem. In the sector unpolluted, close to the Milazzo Cape, foraminiferal assemblages exhibit high values of species richness and foraminiferal density while trace element concentrations and their EFs are very low. Here, the highest densities of Miliolids and epiphytic species are present. On the contrary, in the sector polluted, from the marinas to the crude oil refinery, foraminiferal density and species diversity are low, and assemblages are dominated, albeit with very low densities, by species that tolerate stressed environmental conditions, such as LOFAs, agglutinants and Ammonia spp. Here, the highest trace elements concentrations of Pb, Zn and Cu and related EFs were detected. Eastwards, in the sector moderately polluted, foraminiferal populations are quite poor. They are characterised by low values of species richness and foraminiferal densities, nevertheless trace element concentrations become lower than in the other sectors and their EFs are often below 1. Deformed foraminifera, with percentages up to 7.14 %, were found in all three of the sectors. Differences in benthic foraminiferal assemblages, coupled with results from statistical analysis, indicate that anthropogenic trace element pollution could be considered as one of the most important causes of the modifications of foraminiferal assemblages in the study area. PMID:23828269

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

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

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

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

    USGS Publications Warehouse

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

    2003-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-04-01

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

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

    PubMed Central

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

    2014-01-01

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

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

    PubMed

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

    2014-07-01

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

  6. Monitoring the recolonization of the Mt Pinatubo 1991 ash layer by benthic foraminifera

    E-print Network

    Kaminski, Michael A.

    ; succession; recovery; South China Sea 1. Introduction The 1991, June 15th eruption of Mt Pinatubo was by some estimates one of the greatest volcanic event of the 20th century, forming a cloud that extended from., 1995; Wiesner and Wang, 1996; Wiesner et al., unpublished data, 2001). Close to the volcano, parts

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

    NASA Astrophysics Data System (ADS)

    Ferraro, Steven P.; Cole, Faith A.

    2011-07-01

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

  8. Earth's Layers

    NSDL National Science Digital Library

    Mrs. Walls

    2011-01-30

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

  9. Knowledge of Brazilian benthic marine fauna throughout time.

    PubMed

    Longo, Leila de Lourdes; Amado Filho, Gilberto Menezes

    2014-01-01

    The ecosystems of Brazil's continental shelf and oceanic islands comprise a variety of environments that display unique geomorphological and geophysical features and biotic components. The quest to attain knowledge of Brazilian marine fauna is hampered by coastline length, biodiversity, a high rate of endemism, and a shortage of specialized researchers. Based on a systematic bibliographic review, the article offers an overview of the history, current knowledge, and outlook for the field of marine biodiversity in Brazil. Our findings show that government initiatives have afforded greater knowledge of Brazilian marine fauna species and opened new perspectives, including reliance on complex tools to describe benthic marine habitats in terms of their geological, geophysical, and biotic composition. PMID:25338037

  10. Benthic Exchange and Biogeochemical Cycling in Permeable Sediments

    NASA Astrophysics Data System (ADS)

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

    2014-01-01

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

  11. Effect of exposure method on benthic organism responses

    SciTech Connect

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

    1995-12-31

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

  12. Probabilistic sequence alignment of Late Pleistocene benthic ?18O data

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    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.

  13. Antarctic Benthic Fauna in the Global Climate Change

    NASA Astrophysics Data System (ADS)

    Kidawa, Anna; Janecki, Tomasz

    2011-01-01

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

  14. The Physics of Broadcast Spawning in Benthic Invertebrates

    NASA Astrophysics Data System (ADS)

    Crimaldi, John P.; Zimmer, Richard K.

    2014-01-01

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

  15. Benthic foraminifera and environmental changes in Long Island Sound

    USGS Publications Warehouse

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

    2000-01-01

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

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

    SciTech Connect

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

    1995-05-01

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

  17. Benthic nutrient sources to hypereutrophic upper Klamath Lake, Oregon, USA.

    PubMed

    Kuwabara, James S; Topping, Brent R; Lynch, Dennis D; Carter, James L; Essaid, Hedeff I

    2009-03-01

    Three collecting trips were coordinated in April, May, and August 2006 to sample the water column and benthos of hypereutrophic Upper Klamath Lake (OR, USA) through the annual cyanophyte bloom of Aphanizomenon flos-aquae. A pore-water 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/m(2)/d. The mass flux over an approximate 200-km(2) 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/m(2)/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 10(4) individuals/m(2), 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. PMID:18980391

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

    USGS Publications Warehouse

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

    1995-01-01

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

  19. Suspended Matter in Deep Ocean Water

    Microsoft Academic Search

    Maurice Ewing; Edward M. Thorndike

    1965-01-01

    A nepheloid layer has been observed by optical means in the lower part of the water column on the continental slope and rise. By sampling it has been found to be a suspension of lutite, apparently in sufficient quantity to induce downslope flow. Sediment transported in the nepheloid layer may be a major component of deep-sea sediment bodies.

  20. Particulate matter in the south Atlantic Ocean

    E-print Network

    Wood, Megan Maria

    1993-01-01

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

  1. 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

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

    E-print Network

    . Keywords: bottom trawl fishing; benthic communities; photographic survey; fishing impact; model averaging for the financial support provided by the National Science and Engineering Research Council (NSERC) and for the ship

  3. Object-based benthic habitat mapping in the Florida Keys from hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Zhang, Caiyun; Selch, Donna; Xie, Zhixiao; Roberts, Charles; Cooper, Hannah; Chen, Ge

    2013-12-01

    Accurate mapping of benthic habitats in the Florida Keys is essential in developing effective management strategies for this unique coastal ecosystem. In this study, we evaluated the applicability of hyperspectral imagery collected from Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) for benthic habitat mapping in the Florida Keys. An overall accuracy of 84.3% and 86.7% was achieved respectively for a group-level (3-class) and code-level (12-class) classification by integrating object-based image analysis (OBIA), hyperspectral image processing methods, and machine learning algorithms. Accurate and informative object-based benthic habitat maps were produced. Three commonly used image correction procedures (atmospheric, sun-glint, and water-column corrections) were proved unnecessary for small area mapping in the Florida Keys. Inclusion of bathymetry data in the mapping procedure did not increase the classification accuracy. This study indicates that hyperspectral systems are promising in accurate benthic habitat mapping at a fine detail level.

  4. 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...

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

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  6. 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 ...

  7. 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...

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

    PubMed

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

    2006-01-01

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

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

    EPA Science Inventory

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

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

    EPA Science Inventory

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

  11. 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...

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

    EPA Science Inventory

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

  13. 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,...

  14. 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...

  15. 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...

  16. 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. ...

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

    EPA Science Inventory

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

  18. RESEARCH ARTICLE -BASED ON MIR INVESTIGATIONS IN LAKE GENEVA Spatial heterogeneity of benthic methane dynamics

    E-print Network

    Wehrli, Bernhard

    RESEARCH ARTICLE - BASED ON MIR INVESTIGATIONS IN LAKE GENEVA Spatial heterogeneity of benthic of the special issue ``e´LEMO ­ investigations using MIR submersibles in Lake Geneva''. Electronic supplementary

  19. RESEARCH ARTICLE -BASED ON MIR INVESTIGATIONS IN LAKE GENEVA Spatial heterogeneity of benthic methane dynamics

    E-print Network

    Wehrli, Bernhard

    RESEARCH ARTICLE - BASED ON MIR INVESTIGATIONS IN LAKE GENEVA Spatial heterogeneity of benthic´LEMO ­ investigations using MIR submersibles in Lake Geneva''. Electronic supplementary material The online version

  20. BENTHIC DIATOM AUTECOLOGY AND INFERENCE MODEL DEVELOPMENT FROM THE CANADIAN HIGH ARCTIC ARCHIPELAGO1

    E-print Network

    Vincent, Warwick F.

    assemblages were analyzed from 64 lakes and ponds from Alert, Ellesmere Island and Mould Bay, Prince Patrick words: autecology; benthic; diatoms; dis- solved organic carbon; Ellesmere Island; High Arc- tic

  1. 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...

  2. 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...

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

    E-print Network

    Boyer, Edmond

    been found to occur in 2 species of benthic octopuses (Bustamante et al. 1998). Generally, cephalopods for the Kerguelen octopuses were particularly high. Such high Cd levels have also been reported for some Antarctic

  4. 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...

  5. EVALUATION OF BENTHIC MACROINVERTEBRATE BIOMASS METHODOLOGY. PART 1. LABORATORY ANALYTICAL METHODS

    EPA Science Inventory

    Evaluation of analytical methods employed for wet weight (live or preserved samples) of benthic marcoinvertebrates reveals that centrifugation at 140 x gravity for one minute yields constant biomass estimates. Duration of specimen exposure in ethanol, formalin, and formol (formal...

  6. 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...

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

    EPA Science Inventory

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

  8. 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...

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

    E-print Network

    Canberra, University of

    concentrations in polychaetes and molluscs of Mannering Bay were up to 58 times higher than those from Nord's Wharf. Two benthic organisms, the eunicid polychaete Marphysa sanguinea and the bivalve mollusc Spisula

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

    A high-resolution quantitative study of benthic foraminifera across the expanded and continuous Cretaceous/Paleogene (K/Pg) boundary at the Galanderud section in northern Iran provides an excellent record of the K/Pg event. The benthic foraminiferal assemblages, in contrast to the planktic foraminifers, did not suffer mass extinction at the K/Pg boundary. Uppermost Maastrichtian assemblages are well preserved and highly diverse. Only ~3% of the benthic species became extinct, including Bolivinoides draco, Eouvigerina subsculptura, Neoflabellina sp. and Praebulimina reussi. Other species are temporarily absent for a short interval after the K/Pg boundary. Benthic foraminifera indicate outer neritic-uppermost bathyal depths during the Plummerita hantkeninoides Zone until 70 cm below the K/Pg boundary. This interval contains abundant species of Bolivinoides draco, Gaudryina pyramidata, Cibicidoides hyphalus, P. reussi, and Sitella cushmani. The paleodepth decreased to outer neritic in the uppermost Maastrichtian based on the dominance of Stensioeina excolata, G. pyramidata, Cibicidoides pseudoacutus, and Coryphostoma incrassata forma gigantea. On the other hand, some species such as P. reussi and C. hyphalus, which are normally found at bathyal depths, decreased in their abundances. These data suggest a sea-level fall at the end of Maastrichtian. Additional evidence for sea-level fall is a decrease of planktic/benthic ratio from ~60% to ~40% in the uppermost Maastrichtian. The K/Pg clay layer is characterized by a high abundance of opportunistic species such as Cibicidoides spp., C. pseudoacutus, and Tappanina selemensis. The drastic change of benthic foraminiferal assemblages coincides with a sharp drop in magnetic susceptibility and %CaCO3, mass extinction of planktic foraminifera, a sharp enrichment in Ir, and a 2.25‰ negative excursion in ?13C at the K/Pg boundary, which is largely compatible with the catastrophic effects of an asteroid impact on Earth that briefly, but severely destabilized the oceanic phytoplankton food webs. Isothermal Remanent Magnetization (IRM) curves treated by the cumulative log-Gaussian function shows that hematite (or goethite) and magnetite are the main magnetic minerals in the K/Pg clay layer, whereas large and small magnetite characterize the Maastrichtian and the Danian sediments, respectively. The dominance of hematite over magnetite at the K/Pg boundary explains the lack of the characteristic positive magnetic susceptibility peak observed in other sections suggesting higher oxidation state of the Galanderud depositional environment during the impact. The presence of three calcareous dinoflagellate chalk layers and large excursions in O- and C-isotopic compositions in basal Danian Zone P0 highlight the instability of the ecosystem immediately following the K/Pg boundary. In the Parvularugoglobigerina eugubina and Parasubbotina pseudobulloides Zones, there is an increase in both diversity and infaunal morphogroups, and a slight decrease of the epifaunal morphogroups; some deeper species increase in abundance including Gyroidinoides globosus and Marssonella oxycona. These changes might indicate a sea level rise and uppermost bathyal paleodepths in the early Danian, but it might also indicate improved conditions at the seafloor including greater flux of organic matter. These abrupt paleoenvironmental changes at the K/Pg boundary are correlated in age to the Chicxulub impact event and to the Deccan Phase 2; the contribution of each event is currently under study.

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

    E-print Network

    Newton, Adrian Charles

    1994-01-01

    THE DISTRIBUTION AND ECOLOGY OF BENTHIC FORAMINIFERA AND ASSOCIATED MEIOFAUNA IN THE NORTHEAST WATER POLYNYA, GREENLAND A Thesis by ADRIAN CHARLES NEWTON Submitted to Texas ASSAM University in partial fulfillment of the requirements... The Distribution and Ecology of Benthic Foraminifera and Associated Meiofauna in the Northeast Water Polynya, Greenland, (August 1994) Adrian Charles Newton, BSc. (Hons. ), Southampton University Chair of Advisory Committee: Dr. Gilbert T. Rowe Abundance...

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

    SciTech Connect

    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

    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.

  13. Dams and Flow in the Cotter River, Australia: Effects on Instream Trophic Structure and Benthic Metabolism

    Microsoft Academic Search

    Heath Chester; Richard Norris

    2006-01-01

    This study assessed benthic macroinvertebrates and periphyton and its responses to managed river-flows, in riffles downstream\\u000a of three dams on the Cotter River, Australian Capital Territory. Benthic macroinvertebrates and periphyton were also assessed\\u000a in adjacent tributaries of the river, as well as in a nearby unregulated river and its tributaries. Food sources of four macroinvertebrate\\u000a taxa (Leptophlebiidae, Elmidae, Glossosomatidae and

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

    NASA Astrophysics Data System (ADS)

    Stief, P.

    2013-12-01

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

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

    NASA Astrophysics Data System (ADS)

    Stief, P.

    2013-07-01

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

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

    Microsoft Academic Search

    D. R. Currie; Leanne R. Isaacs

    2005-01-01

    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

  17. Benthic community re-adjustment following dredging of a muddy-maerl matrix

    Microsoft Academic Search

    S De Grave; A Whitaker

    1999-01-01

    Changes in the benthic infaunal community structure at a location in south-west Ireland subject to dredging impacts were studied. Dredging of a muddy-maerl matrix takes place with a seasonally varying frequency of 2–5 times per month. The benthic infauna at a currently dredged site was compared to a fallowed portion of the area, at which extraction ceased 6 months prior

  18. Benthic Algae in High Altitude Streams of the Alps – a Neglected Component of the Aquatic Biota

    Microsoft Academic Search

    E. Rott; M. Cantonati; L. Füreder; P. Pfister

    2006-01-01

    This is a review on benthic algae from streams situated above the tree line in the Alps. It integrates published and unpublished\\u000a data from alpine streams in Austria and in the Trento Province (Northern Italy). The main focus is on the structural and taxonomic\\u000a composition of benthic algae including macro- and micro-algae and their contribution to the epilithic biofilm and

  19. Effects of Hurricane Katrina on benthic macroinvertebrate communities along the northern Gulf of Mexico coast

    Microsoft Academic Search

    Virginia D. Engle; Jeffrey L. Hyland; Cynthia Cooksey

    2009-01-01

    The effects of Hurricane Katrina on benthic fauna and habitat quality in coastal waters of Louisiana, Mississippi, and Alabama,\\u000a USA, were assessed in October, 2005, 2 months after the hurricane made landfall between New Orleans, LA and Biloxi, MS. Benthic\\u000a macrofaunal samples, sediment chemical concentrations, and water quality measurements from 60 sites in Lake Pontchartrain\\u000a and Mississippi Sound were compared with

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

    PubMed Central

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

    2011-01-01

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

  1. Protistan bacterivory and benthic microbial biomass in an intertidal creek mudflat

    Microsoft Academic Search

    Jt Hollibaugh

    2008-01-01

    We examined 8 sediment samples collected at 3 h intervals at Dean Creek (Sapelo Island, Georgia) to assess the impact of protist bacterivory on the standing crops of benthic bacterial biomass. The combined biomass of the benthic microalgae (BMA), bacteria, heterotrophic protists, and meiofauna ranged from 0.41 to 0.57 mg C g1 wet sediment (gws) in the samples examined. BMA

  2. Responses of Biofilm-Dwelling Ciliate Communities to Planktonic and Benthic Resource Enrichment

    Microsoft Academic Search

    Helge Norf; Hartmut Arndt; Markus Weitere

    2009-01-01

    Four experiments covering different seasons were performed to test the impact of increased benthic and planktonic resource\\u000a availability on the structure of biofilm-dwelling ciliate communities which were cultivated in river bypass systems. The growth\\u000a of benthic bacteria was stimulated by the addition of dissolved organic carbon. The enrichment of the planktonic resource\\u000a was achieved by supplementation with suspended bacteria. It

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

    PubMed Central

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

    2012-01-01

    The high degree of physical factors in intertidal estuarine ecosystem increases material processing between benthic and pelagic compartments. In these ecosystems, microphytobenthos resuspension is a major phenomenon since its contribution to higher trophic levels can be highly significant. Understanding the sediment and associated microphytobenthos resuspension and its fate in the water column is indispensable for measuring the food available to benthic and pelagic food webs. To identify and hierarchize the physical/biological factors potentially involved in MPB resuspension, the entire intertidal area and surrounding water column of an estuarine ecosystem, the Bay des Veys, was sampled during ebb tide. A wide range of physical parameters (hydrodynamic regime, grain size of the sediment, and suspended matter) and biological parameters (flora and fauna assemblages, chlorophyll) were analyzed to characterize benthic-pelagic coupling at the bay scale. Samples were collected in two contrasted periods, spring and late summer, to assess the impact of forcing variables on benthic-pelagic coupling. A mapping approach using kriging interpolation enabled us to overlay benthic and pelagic maps of physical and biological variables, for both hydrological conditions and trophic indicators. Pelagic Chl a concentration was the best predictor explaining the suspension-feeders spatial distribution. Our results also suggest a perennial spatio-temporal structure of both benthic and pelagic compartments in the ecosystem, at least when the system is not imposed to intense wind, with MPB distribution controlled by both grain size and bathymetry. The benthic component appeared to control the pelagic one via resuspension phenomena at the scale of the bay. Co-inertia analysis showed closer benthic-pelagic coupling between the variables in spring. The higher MPB biomass observed in summer suggests a higher contribution to filter-feeders diets, indicating a higher resuspension effect in summer than in spring, in turn suggesting an important role of macrofauna bioturbation and filter feeding (Cerastoderma edule). PMID:22952910

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

    PubMed

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

    2015-01-01

    Dreissenid mussels have invaded the Laurentian Great Lakes causing dramatic changes to benthic-pelagic interactions. Despite research on food web impacts, there is limited data on mussel effects on benthic bacterial communities. This study examined effects of dreissenid mussels and benthic algae on sediment bacterial community composition and diversity. Triplicate experimental sediment plus lake water microcosms were used and either mussels, benthic algae or both were added. Changes in water nutrient chemistry and sediment bacterial communities were monitored using 16S rRNA amplicon sequencing, over 21 days. When mussels were present, nitrate and soluble reactive P increased significantly as the dominant N and P forms. Bacterial diversity increased in all microcosms, although bacterial community composition was distinct between treatment. Higher nitrate in mussel microcosms was accompanied by increases in nitrifying taxa (Nitrospira, Nitrosomonas), which are important in oxidizing mussel-excreted ammonium. Microcosms with algal additions showed increases in bacterial taxa capable of degrading algal cellulose, and Pelagibacter (SAR11) disappeared from all but control microcosms. This study suggests that bacterial communities in lake sediments respond to mussels and algae. Functional analysis of bacterial communities provides insights into changes in microbially mediated benthic nutrient transformations associated with invasive dreissenid mussels and benthic algae in lake ecosystems. PMID:25764528

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

    SciTech Connect

    Dwyer, F.J.; Canfield, T.J.; Ingersoll, C.G.; Kemble, N.E.; Mount, D.R. [National Biological Service, Columbia, MO (United States)

    1995-12-31

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

  6. Explosive diversification following a benthic to pelagic shift in freshwater fishes

    PubMed Central

    2013-01-01

    Background Interspecific divergence along a benthic to pelagic habitat axis is ubiquitous in freshwater fishes inhabiting lentic environments. In this study, we examined the influence of this habitat axis on the macroevolution of a diverse, lotic radiation using mtDNA and nDNA phylogenies for eastern North America’s most species-rich freshwater fish clade, the open posterior myodome (OPM) cyprinids. We used ancestral state reconstruction to identify the earliest benthic to pelagic transition in this group and generated fossil-calibrated estimates of when this shift occurred. This transition could have represented evolution into a novel adaptive zone, and therefore, we tested for a period of accelerated lineage accumulation after this historical habitat shift. Results Ancestral state reconstructions inferred a similar and concordant region of our mtDNA and nDNA based gene trees as representing the shift from benthic to pelagic habitats in the OPM clade. Two independent tests conducted on each gene tree suggested an increased diversification rate after this inferred habitat transition. Furthermore, lineage through time analyses indicated rapid early cladogenesis in the clade arising after the benthic to pelagic shift. Conclusions A burst of diversification followed the earliest benthic to pelagic transition during the radiation of OPM cyprinids in eastern North America. As such, the benthic/pelagic habitat axis has likely influenced the generation of biodiversity across disparate freshwater ecosystems. PMID:24341464

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

    PubMed

    Lillicrap, Adam; Schaanning, Morten; Macken, Ailbhe

    2015-03-17

    Activated carbon (AC) has long been associated with the capacity to effectively remove organic substances from aquatic and sediment matrices; however, its use in remediation purposes has drawn some concern due to possible impacts on benthic communities. Within the inner Oslofjord, the use of AC has been well documented for reducing the risks associated with dioxins or dioxin-like compounds from contaminated areas. However, benthic surveys performed on areas treated with AC have revealed that the abundance of organisms inhabiting these areas can be reduced significantly in the subsequent years following treatment. The reason for the reduction in the benthic communities is currently unknown, and therefore, an integrated approach to assess the effects of 2 different forms of AC (biogenic and petrogenic) on benthic organisms has been performed. A battery of 3 different benthic organisms with different feeding and life-cycle processes has been used encompassing sediment surface feeders, sediment ingestors, and sediment reworkers. Results of the tests indicated that although AC is not acutely toxic at concentrations up to 1000 mg/L, there may be physical effects of the substance on benthic dwelling organisms at environmentally relevant concentrations of AC at remediated sites. PMID:25723541

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

    NASA Astrophysics Data System (ADS)

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

    2004-05-01

    Long Island Sound (LIS) is an estuary in a heavily urbanized region; Long Island lies to its South, New York City (NYC) to its West and Connecticut to its North. The Connecticut River contributes >70% of the fresh water influx. LIS has a narrow opening to the West (into East River), but exchange with the ocean occurs dominantly at its eastern end, resulting in an east-west gradient in salinity. An east-west gradient is also present in indicators of anthropogenic contamination in the surface sediments (e.g., trace metals) because western LIS is close to the major source of anthropogenic input (NYC). In addition, bottom currents focus fine-grained, contaminant-loaded sediments there. Since the early 1970's western LIS and parts of central LIS have suffered summer hypoxia, probably as a result of increased algal growth caused by anthropogenic nitrogen input. Benthic foraminifera are eukaryote heterotrophic organisms with a calcareous or agglutinated test. We investigated changes in their populations over time in about 2m-long gravity cores in westernmost (WLIS75GGC1; 73o 40'W, 40o 52'N, 19m waterdepth) and coastal central LIS (B1GGC1; 73o 4'W, 41o 10'N, 8m water depth), to document environmental changes over the last millennium, including the time of European settlement and the industrial revolution and population increase. An age model was derived from metal pollution records and 14C dating. Before European settlement, the low-diversity benthic faunas in core B1GGC1, at a depth within the zone of light penetration, were dominated by Elphidium excavatum, a species feeding on living diatoms. In western LIS (below the zone of light penetration) this species was less abundant and Elphidium incertum and Buccella frigida were common. In both cores, the absolute abundance of benthic foraminifera and the relative abundance of Elphidium excavatum increased in the early 1800's, coinciding with a time of rapid increase in human population around LIS and slightly before an increase in trace metal concentration. The ecological changes may have been caused by increased productivity of diatoms resulting from beginning anthropogenic eutrophication. From the middle 1960's on, absolute foraminiferal abundance decreased and Ammonia beccarii, formerly absent or rare, became common to dominant in WLIS75GGC1; in B1GGC1 a similar but less severe change started in the 1970's. The increase in relative abundance of A. beccarii could have been caused by hypoxia (possibly in conjunction with rising bottom water temperatures), but both Ammonia and Elphidium species survive hypoxia in the laboratory. We suggest that high N/Si resulting from strong eutrophication might favor primary producers other than diatoms (e.g., dinoflagellates, cyanobacteria), making E. excavatum less competitive. The LIS coastal ecosystem thus changed significantly with the enhanced nutrient input associated with human population growth in the middle 1800's, and again with more severe eutrophication over the last few decades.

  9. Recent benthic ostracoda of Pahang River Delta, Pahang Darul Makmur

    NASA Astrophysics Data System (ADS)

    Noraswana, N. F.; Ramlan, O.

    2014-09-01

    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.

  10. Sensitivity of Heterogeneous Marine Benthic Habitats to Subtle Stressors

    PubMed Central

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

    2013-01-01

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

  11. Effects of chemical disturbances on intertidal benthic assemblages.

    PubMed

    Mayer-Pinto, Mariana; Ignacio, Barbara Lage

    2015-02-15

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

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

    SciTech Connect

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

    2007-06-01

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

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

    NASA Astrophysics Data System (ADS)

    Ferraro, Steven P.; Cole, Faith A.

    2012-05-01

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

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

    PubMed

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

    2015-03-01

    Competition for resources between coexisting phytoplankton and benthic algae, but with different habitats and roles in functioning of lake ecosystems, profoundly affects dynamics of shallow lakes in the process of eutrophication. An experiment was conducted to test the hypothesis that combined enrichment with nitrogen (N) and phosphorus (P) would be a greater benefit to phytoplankton than benthic algae. The growth of phytoplankton and benthic algae was measured as chlorophyll a (Chl a) in 12 shallow aquatic mesocosms supplemented with N, P, or both. We found that enrichment with N enhanced growth of benthic algae, but not phytoplankton. P enrichment had a negative effect on benthic algal growth, and no effect on the growth of phytoplankton. N+P enrichment had a negative effect on benthic algae, but enhanced the growth of phytoplankton, thus reducing the proportion of benthic algae contributing to the combined biomass of these two groups of primary producers. Thus, combined N+P enrichment is more favorable to phytoplankton in competition with benthic algae than enrichment with either N or P alone. Our study indicates that combined enrichment with N+P promotes the dominance of phytoplankton over benthic algae, with consequences for the trophic dynamics of shallow lake ecosystems. PMID:25304240

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

    PubMed

    Larras, Floriane; Montuelle, Bernard; Bouchez, Agnès

    2013-10-01

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

  16. Down-core distribution of live and dead deep-water benthic foraminifera in box cores from the Weddell Sea and the California continental borderland

    NASA Astrophysics Data System (ADS)

    Mackensen, Andreas; Douglas, Robert G.

    1989-06-01

    Five short cores sub-sampled from box cores from three sites in the eastern Weddell Sea off Antarctica and in the eastern Pacific off southern California, covering a range in water depth from 500 to 2000 m, were analysed for the down-core distribution of live (stained with Rose Bengal) and dead benthic foraminifera. In the California continental borderland, Planulina ariminensis, Rosalina columbiensis and Trochammina spp. live attached to agglutinated polychaetes tubes that rise above the sediment-water interface. Bolivina spissa lives exclusively in or on the uppermost sediment. Stained specimens of Chilostomella ovoidea are found down to 6 cm within the sediment and specimens of Globobulimina pacifica down to a maximum of 8 cm. ?13C values of live G. pacifica decrease with increasing depth from the sediment surface down to 7 cm core depth, indicating that this infaunal species utilizes 13C-depleted carbon from pore waters. In the dead, predominantly calcareous benthic forminiferal assemblage, selective dissolution of small delicate tests in the upper sediment column causes a continuous variation in species proportions. In the eastern Weddell Sea, the calcareous Bulimina aculeata lives in a carbonate corrosive environment exclusively in or on the uppermost sediment. The arenaceous Cribrostomoides subglobosum, Recurvoides contorus and some Reophax species are frequently found within the top 4 cm of the sediment, whereas stained specimens of Haplophragmoides bradyi, Glomospira charoides and Cribrostomoides wiesneri occur in maximum abundance below the uppermost 1.5 cm. Species proportions in the dead, predominantly arenaceous, benthic foraminiferal assemblage change in three distinct steps. The first change is caused by calcite dissolution at the sediment-water interface, the second coincides with the lower boundary of intense bioturbation, and the third results from the geochemical shift from oxidizing to reducing conditions below a compacted ash layer.

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

    USGS Publications Warehouse

    Sheibley, Richard W.; Paulson, Anthony J.

    2014-01-01

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

  18. The use of fossil benthic foraminifera to define reference conditions for present-day marine waters

    NASA Astrophysics Data System (ADS)

    Bouchet, V. M. P.; Hess, S.; Dolven, J. K.; Alve, E.

    2012-04-01

    The implementation of legislations is generating a fruitful debate amongst marine scientists about how to define efficient and reliable bio-assessment tools to monitor the ecological quality status (EcoQS) of marine waters. According to those legislations, EcoQS assessment needs a "reference condition" with which to compare the present-day condition at a site. The fossil record has a potential to reconstruct PaleoEcoQS and thereby establish in situ reference conditions from pre-impact times. Unlike most macrofaunal groups which are the most commonly used biological quality indicator in these environments, benthic foraminifera leave a fossil record and therefore allow the reconstruction of human-induced environmental disturbance over decades to centuries. Foraminifera have the potential to serve as ecosystem characterization tools in modern and past marine environments. We compared the response of benthic foraminifera, macrofauna and selected environmental parameters from the same sites in areas with relatively stable salinity and temperature conditions but otherwise contrasting environmental properties (e.g., varying degree of anthropogenic impact). In August 2008, replicate samples for living (stained) benthic foraminifera and macrofauna from 27 stations in 11 silled fjords along the Norwegian Skagerrak coast were examined. Environmental data (bottom-water dissolved-oxygen, TOC, TN and pigments) were analysed for each station. The same kind of data were analysed from 2 recolonisation sites in the inner Oslofjord. In addition, the PaleoEcoQS during the past century was reconstructed using benthic foraminifera and selected environmental parameters from 11 stations in the inner Oslofjord. Results show that living benthic foraminifera are at least as reliable to define present-day EcoQS as conventional methods. Fossil benthic foraminifera can also define ecological status of reference conditions from pre-impacted times. This is not possible using conventional methods. Consequently, benthic foraminifera are excellent bioindicators of human-induced environmental impacts over time.

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

    PubMed

    Hall, Lenwood W; Anderson, Ronald D

    2013-08-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

    We investigated the fluctuations of carbon and nitrogen stable isotope ratios in benthic consumers and their potential food sources to determine the spatial and temporal variations in the utilization of available organic matter, indicating the origin and pathways of energy from Yura Estuary to Tango Sea, Japan. Field samplings were conducted from the upper estuary to offshore with sampling frequency of twice per season from April (spring) 2006 to February (winter) 2007. The ?13C signatures of the upper and lower estuary benthos showed depleted and in wide range (-28.9‰ to -13.5‰) compared to the enriched and within narrow range signatures of marine benthos (-20.6‰ to -14.0‰) in all seasons. On the contrary, the ?15N signatures of benthic communities showed decreasing trend seaward and summer values were different from the other seasons. Using the dual isotope and multisource mixing models, we estimated the relative contributions of potential food sources to the benthos diet. River POM played an important source of energy for the estuarine benthos, especially in winter when river discharge was high. Marine POM served as an important alternative food for the estuarine benthos from spring to autumn when seawater intruded the bottom estuary. Benthic microalgae were the major food source at the shallow coast throughout the year, while marine POM fueled the deep coast and offshore benthic food webs. Spatial and temporal feeding variations in estuarine benthic communities were driven by the hydrology of the estuary, whereas primary production and transport of food source dictated diet variations of marine benthic communities. The elucidation of the dynamic energy subsidy among aquatic systems highlights the importance of the land-sea transition zones that is crucial for benthic secondary productions.

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    Continental 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.

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

    USGS Publications Warehouse

    Bradfield, A.D.

    1986-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Hargrave, C. W.

    2005-05-01

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

  4. Contrasting effects of hydrological stability and flow extremes on benthic and hyporheic invertebrate communities

    NASA Astrophysics Data System (ADS)

    Stubbington, Rachel; Wood, Paul J.; Reid, Ian

    2010-05-01

    In lotic ecosystems, the most common disturbance events occur at the extremes of the hydrological continuum, i.e. spates and streambed drying. During spates, high flow velocities can mobilise sediments and displace invertebrates, and during streambed drying, loss of free water can cause mass mortality of many aquatic taxa. In both cases, invertebrates inhabiting the surface sediments are subject to a greater frequency and magnitude of disturbance than those in the hyporheic zone, and this habitat may therefore act as a refugium. Between extreme events, stable hydrological conditions allow competitive species to thrive, which can cause biotic interactions to increase. We compared the effects of flow extremes and hydrological stability on benthic and hyporheic invertebrate communities. Hydrological conditions included spates, flow recession, and localised streambed drying. During flow recession, competitive benthic taxa, particularly Gammarus pulex (Amphipoda) increased in abundance in surface sediments, causing community diversity to decline. A concurrent increase in the hyporheic abundance of G. pulex indicated that the hyporheic zone may act as a refugium from increasing biotic pressures in the benthic sediments. In contrast, spate events caused severe reductions in both benthic and hyporheic invertebrate abundance, and declines in G. pulex abundance were particularly pronounced; spate events were therefore important in increasing both benthic and hyporheic community diversity.

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

  6. A deep-sea sediment transport storm

    NASA Astrophysics Data System (ADS)

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

    1988-02-01

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

  7. Benthic substrate classification map: Gulf Islands National Seashore

    USGS Publications Warehouse

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

    2013-01-01

    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.

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

    NASA Astrophysics Data System (ADS)

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

    2013-12-01

    The opening and closure of seaways have immanent paleoclimatic, paleoceanographic and paleobiogeographic consequences as they determine the exchange of water masses. During the Oligocene to Miocene severe alterations of marine gateway configuration shaped the evolution of the Mediterranean - Paratethys region. From early to middle Burdigalian (20.4-17.5 Myrs) the Burdigalian Seaway connected the western Mediterranean Sea with the Central Paratethys Sea via the North Alpine Foreland Basin (NAFB). Its evolution resulted in profound paleoceanograpic and -geographic changes, and initiated a wave of faunal immigration from the Atlantic and Mediterranean into the Paratethys that had a severe impact on marine ecosystems. A detailed Early Miocene proxy record integrating seismic images, microfossil assemblages and geochemical analyses has been recently established for the Puchkirchen Basin (PB) as part of the NAFB. Herein, we exemplarily show the reconstruction of the dynamic early to middle Burdigalian paleoenvironment based on a quantitative evaluation of benthic foraminiferal assemblages from drill-sites and outcrops. Four major phases in PB development are distinguished, and new stratigraphic constraints allow discussing the results in the context of the evolution of the Burdigalian Seaway: 1. The global early Burdigalian sea-level rise initiated a marine transgression in the NAFB. In the PB, a long-lived basin-axial channel system was reactivated resulting in turbiditic and mass-flow deposition. The unstable upper bathyal environment is reflected in a low diverse autochthonous benthic foraminiferal fauna mainly composed of Bathysiphon filiformis. 2. The perpetuating transgression flooded large shelf areas and established the Burdigalian Seaway. The channel belt was cut off from its sediment sources and shut down. Subsequently, sedimentation was controlled by episodic turbidites from the southern basin margin, and large NE prograding delta fans. High sedimentation rates and strong terrestrial input led to the development of diverse foraminiferal faunas that are largely composed of agglutinated species. The encountered astrorhizids, ammodiscids and textualriids are adapted to high organic matter input and suboxic bottom-waters. Assemblages dominated by Bathysiphon filiformis occur in phases of turbidite deposition. 3. At ~19 Ma the Burdigalian Seaway became a vast shelf sea when increasing sedimentation rates led to the upfill of the PB. At the same time marine sedimentation reached its maximum extent in the NAFB. Characteristic hyaline shelf faunas composed of Lenticulina, Amphicoryna, Melonis, Cibcidoides and Ammonia developed along the inner-outer neritic shelf environments. 4. The beginning of a regression at ~18 Ma heralded the closure of the Burdigalian Seaway. Biofacies distribution shows a prograding tide-influenced shelf and widespread shallow water environments largely dominated by Ammonia, Elphidium and Cibicidoides developed. The closure of the Burdigalian Seaway initiated a major paleogeographic reorganization resulting in the final retreat of the Central Paratethys towards the east.

  9. Competition between Ammonia-Oxidizing Bacteria and Benthic Microalgae

    PubMed Central

    Risgaard-Petersen, Nils; Nicolaisen, Mette H.; Revsbech, Niels Peter; Aa Lomstein, Bente

    2004-01-01

    The abundance, activity, and diversity of ammonia-oxidizing bacteria (AOB) were studied in prepared microcosms with and without microphytobenthic activity. In the microcosm without alga activity, both AOB abundance, estimated by real-time PCR, and potential nitrification increased during the course of the experiment. AOB present in the oxic zone of these sediments were able to fully exploit their nitrification potential because NH4+ did not limit growth. In contrast, AOB in the alga-colonized sediments reached less than 20% of their potential activity, suggesting starvation of cells. Starvation resulted in a decrease with time in the abundance of AOB as well as in nitrification potential. This decrease was correlated with an increase in alga biomass, suggesting competitive exclusion of AOB by microalgae. Induction of N limitation in the oxic zone of the alga-colonized sediments and O2 limitation of the majority of AOB in darkness were major mechanisms by which microalgae suppressed the growth and survival of AOB. The competition pressure from the algae seemed to act on the entire population of AOB, as no differences were observed by denaturing gradient gel electrophoresis of amoA fragments during the course of the experiment. Enumeration of bacteria based on 16S rRNA gene copies and d-amino acids suggested that the algae also affected other bacterial groups negatively. Our data indicate that direct competitive interaction takes place between algae and AOB and that benthic algae are superior competitors because they have higher N uptake rates and grow faster than AOB. PMID:15345441

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

    PubMed

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

    2009-02-01

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

  11. Maximum ecological potential of tropical reservoirs and benthic invertebrate communities.

    PubMed

    Molozzi, Joseline; Feio, Maria João; Salas, Fuensanta; Marques, João Carlos; Callisto, Marcos

    2013-08-01

    The Reference Condition Approach (RCA) is now widely adopted as a basis for the evaluation of the ecological quality of water bodies. In accordance with the RCA, the integrity of communities found in a given location should be analyzed according to their deviation from the communities that would be expected in the absence of anthropogenic disturbances. The RCA was used here with the aim of defining the Maximum Ecological Potential (MEP) of tropical reservoirs located in the hydrographical basin of the Paraopeba River in the state of Minas Gerais, Brazil. Among the reservoirs, Serra Azul is used as a water supply and is located in a core area of environmental protection where tourism is not allowed and the native vegetation is conserved. The benthic macroinvertebrate communities at 90 sites located in three reservoirs were analyzed and sampled every 3 months over 2 years. The temporal patterns of the communities in the three reservoirs were analyzed (2nd-STAGE MDS and ANOSIM) and were not significantly related to seasonal fluctuations in temperature and precipitation. Twenty-eight sites belonging to the Serra Azul reservoir were selected to define the MEP of these reservoirs because these sites had the lowest human disturbance levels. The macroinvertebrate taxa present in the selected MEP sites are similar to those of natural lakes and different from the communities of disturbed sites. The biological classification of these sites revealed two groups with distinct macroinvertebrate communities. This distinction was related to climatic variables, bottom substrate type, the presence of gravel/boulders, coarse sand, silt, clay or muck, depth, and the shoreline substrate zone. These two subsets of biological communities and respective environmental conditions can serve as a basis for the future implementation of ecological quality monitoring programs for tropical reservoirs in the study area. This approach can also, however, be implemented in other geographic areas with artificial or heavily modified water bodies. PMID:23288597

  12. Benthic invertebrate bioassays with toxic sediment and pore water

    USGS Publications Warehouse

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

    1990-01-01

    The relative sensitivities of bioassays to determine the toxicity of sediments were investigated and three methods of making the sample dilutions required to generate dose-response relationships were compared. The assays studied were: (a) Microtox(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.

  13. The significance of phytoplankton photo-adaptation and benthic pelagic coupling to primary production in the South China Sea: Observations and numerical investigations

    NASA Astrophysics Data System (ADS)

    Liu, Kon-Kee; Chen, Ying-Jie; Tseng, Chun-Mao; Lin, I.-I.; Liu, Hong-Bin; Snidvongs, Anond

    2007-07-01

    The primary production in the South China Sea (SCS) has been assessed by a coupled physical-biogeochemical model with a simple NPZD ecosystem [Liu et al., 2002. Monsoon-forced chlorophyll distribution and primary production in the SCS: observations and a numerical study. Deep-Sea Research I 49(8), 1387-1412]. In recent years there have been an increasing number of observations in the SCS that may be used to check the validity of the previous approach. The coupled model of the SCS mentioned above employs a photo-adaptation scheme for the phytoplankton growth and uses the simplest bottom boundary condition of an inert benthic layer. These adopted schemes are checked against observations at the South-East Asian Time-series Study (SEATS) Station in the northern SCS and in the Gulf of Thailand. Numerical experiments with or without photo-adaptation or active benthic processes are carried out in this study. Additional experiments are performed with different parameters used for these processes. The observations at the SEATS Station provide direct evidence for the variable chlorophyll-to-nitrogen ratio in phytoplankton as required by photo-adaptation. It is concluded that a photo-adaptation scheme is critical to the phytoplankton growth, especially for the development of the subsurface chlorophyll maximum (SCM). Without photo-adaptation, the average value of the vertically integrated primary production (IPP) over the whole SCS domain would be 35% lower. It is noted that, the modeled SCM occurs at depths shallower than observations due to physical as well as biological processes employed by the model. Increasing the upper limit of the chlorophyll-to-nitrogen ratio, as suggested by observations, enhances chlorophyll level in the lower part of the euphotic zone and raises primary productivity in areas with rich nutrient supply. The observed values of the IPP in the Gulf of Thailand clearly demonstrate the importance of the benthic-pelagic coupling to the nutrient cycle. Without benthic nutrient regeneration the model grossly underestimates primary production due to failure to build up the nutrient reserve in the Gulf. On the other hand, a fully regenerated flux of particulate organic nitrogen at the sea floor without denitrification produces too strong a primary production. The improved model uses a higher upper limit for the chlorophyll-to-phytoplankton ratio of 3.5 g Chl/mol N and adopts benthic processes of a coupled nitrification-denitrification scheme with denitrification consuming 14% of the detritus flux at the bottom. The model predicts a mean annual IPP value of 406 mg C m -2 d -1 for the SCS, which is 44% higher than that predicted by the original model. The increase can be broken down to 39% attributed to the benthic nutrient regeneration and 5% to the enhanced photo-adaptation. The average IPP is 390 mg C m -2 d -1 for the basin region (>200 m) and 429 mg C m -2 d -1 for the shelf region (<200 m), both of which compare favorably with observed mean values. The model also predicts a mean nitrogen removal flux of 0.16 mmol N m -2 d -1 during denitrification for the shelf region.

  14. 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.

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

    PubMed

    Aloulou, Fatma; EllEuch, Boubaker; Kallel, Monem

    2012-01-01

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

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

    PubMed

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

    2013-12-15

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

  17. Methods for collecting benthic invertebrate samples as part of the National Water-Quality Assessment Program

    USGS Publications Warehouse

    Cuffney, Thomas F.; Gurtz, Martin E.; Meador, Michael R.

    1993-01-01

    Benthic invertebrate communities are evaluated as part of the ecological survey component of the U.S. Geological Survey's National Water-Quality Assessment Program. These biological data are collected along with physical and chemical data to assess water-quality conditions and to develop an understanding of the factors that affect water-quality conditions locally, regionally, and nationally. The objectives of benthic invertebrate community characterizations are to (1) develop for each site a list of tax a within the associated stream reach and (2) determine the structure of benthic invertebrate communities within selected habitats of that reach. A nationally consistent approach is used to achieve these objectives. This approach provides guidance on site, reach, and habitat selection and methods and equipment for qualitative multihabitat sampling and semi-quantitative single habitat sampling. Appropriate quality-assurance and quality-control guidelines are used to maximize the ability to analyze data within and among study units.

  18. Dynamics of Invertebrate Benthic Communities and Drift in a Regulated River of Central Spain

    NASA Astrophysics Data System (ADS)

    Boyero, Luz; Valladolid, María; Arauzo, Mercedes

    2005-08-01

    We document invertebrate benthic and drift dynamics in a regulated river in central Spain at two temporal scales: seasonal (for both benthos and drift) and daily (for drift). The benthic abundance of individuals and taxon richness generally increased in the summer. Drift abundance showed no seasonal or daily variation, but taxon richness of drifting individuals was higher in the spring. Both ben-thos and drift showed clear seasonal changes in taxonomic composition. Interestingly, some benthic taxa showed their highest abundances in the spring, while others were more abundant in the summer. In contrast, most drifting taxa were more abundant in the spring. Different functional feeding groups showed different patterns of variation throughout the year, both in the benthos and the drift. Daily variations in drift were present in very few taxa and functional feeding groups, and only in some seasons.

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

    NASA Astrophysics Data System (ADS)

    Resh, Vincent H.; Price, Donald G.

    1984-01-01

    Sequential sampling is a method for monitoring benthic macroinvertebrates that can significantly reduce the number of samples required to reach a decision, and consequently, decrease the cost of benthic sampling in environmental impact assessments. Rather than depending on a fixed number of samples, this analysis cumulatively compares measured parameter values (for example, density, community diversity) from individual samples, with thresholds that are based on specified degrees of precision. In addition to reducing sample size, a monitoring program based on sequential sampling can provide clear-cut decisions as to whether a priori-defined changes in the measured parameter(s) have or have not occurred. As examples, sequential sampling programs have been developed to evaluate the impact of geothermal energy development on benthic macroinvertebrate diversity at The Geysers, California, and for monitoring the impact of crude oil contamination on chironomid midge [ Cricotopus bicinctus (Meigen) and C. mackenziensis Oliver] population densities in the Trail River, Northwest Territories, Canada.

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

    Microsoft Academic Search

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

    2009-01-01

    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,

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

    Microsoft Academic Search

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

    2006-01-01

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

  2. Monitoring of oxygenic and anoxygenic photosynthesis in a unicyanobacterial bio¢lm, grown in benthic gradient chamber

    Microsoft Academic Search

    Olivier Pringault; Ferran Garcia-Pichel

    2000-01-01

    In order to assess the role of cyanobacteria in the formation and dynamics of microenvironments in microbial mats, we studied an experimental biofilm of a benthic, halotolerant strain, belonging to the Halothece cluster of cyanobacteria. The 12-week-old biofilm developed in a sand core incubated in a benthic gradient chamber under opposing oxygen and sulfide vertical concentration gradients. At the biofilm

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

    Microsoft Academic Search

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

    2002-01-01

    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

  4. Reconstructing the seafloor environment during sapropel formation using benthic foraminiferal trace metals, stable isotopes, and sediment composition

    Microsoft Academic Search

    S. Ní Fhlaithearta; G.-J. Reichart; F. J. Jorissen; C. Fontanier; E. J. Rohling; J. Thomson; G. J. De Lange

    2010-01-01

    The evolution of productivity, redox conditions, temperature, and ventilation during the deposition of an Aegean sapropel (S1) is independently constrained using bulk sediment composition and high-resolution single specimen benthic foraminiferal trace metal and stable isotope data. The occurrence of benthic foraminifer, Hoeglundina elegans (H. elegans), through a shallow water (260 m) sapropel, permits for the first time a comparison between

  5. BENTHIC MICROALGAL CONTROL ON THE NUTRIENT FLUX IN INTER-TIDAL FLATS OF THE LOWER YAQUINA ESTUARY, OREGON

    EPA Science Inventory

    Three sites were selected across the intertidal zone of the lower Yaquina Bay to investigate the role of benthic microalgae in benthic nutrient fluxes. Study sites were selected where microalage were present but without seagrass or mud shrimp. Sediment columns were collected th...

  6. 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...

  7. Applicability of Modern Benthic Foraminiferal Based Paleoproductivity Estimates to the Neogene Record: A Case Study from the South China Sea

    Microsoft Academic Search

    W. Kuhnt; A. Holbourn; S. Hess; Z. Jian

    2003-01-01

    We investigate the applicability of modern benthic foraminiferal based paleoproductivity proxies to fossil assemblages in the South China Sea. This western Pacific marginal basin has a 30 Myr continuous pelagic sediment record and minimal carbonate dissolution, and thus provides ideal boundary conditions for such a test. We relate the composition of modern and Pleistocene to Oligocene benthic foraminiferal assemblages to

  8. 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...

  9. PARASITES OF BENTHIC AMPHIPODS: MICROSPORIDANS OF AMPELISCA AGASSIZI aVDD) AND SOME orHER GAMMARIDEANS

    E-print Network

    PARASITES OF BENTHIC AMPHIPODS: MICROSPORIDANS OF AMPELISCA AGASSIZI aVDD) AND SOME or of benthic amphipods collected during a 2'h-year survey of populations on the continental shelf of amphipod. A microsporidan confined to the abdominal muscles was common in most populations of A. agll8sizi

  10. The role of chironomid larvae in the structure of river benthic communities of the upper and middle Kama River basins

    Microsoft Academic Search

    I. V. Pozdeev; M. S. Aleksevnina

    2008-01-01

    The paper represents results of long-term studies of riverine benthic fauna of Upper and Middle Kama River basins, a region\\u000a with highly heterogeneous hydrologic conditions. The role of chironomid larvae in rheophilic benthic communities is assessed.\\u000a Quantitative parameters of typical chironomid complexes are provided.

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

    E-print Network

    O'Neill, Brian James

    2010-04-02

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

  12. 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...

  13. Crater lake cichlids individually specialize along the benthic-limnetic axis.

    PubMed

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

    2014-04-01

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

  14. Crater lake cichlids individually specialize along the benthic–limnetic axis

    PubMed Central

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

    2014-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Blanchet, Hugues; Gouillieux, Benoît; Alizier, Sandrine; Amouroux, Jean-Michel; Bachelet, Guy; Barillé, Anne-Laure; Dauvin, Jean-Claude; de Montaudouin, Xavier; Derolez, Valérie; Desroy, Nicolas; Grall, Jacques; Grémare, Antoine; Hacquebart, Pascal; Jourde, Jérôme; Labrune, Céline; Lavesque, Nicolas; Meirland, Alain; Nebout, Thiebaut; Olivier, Frédéric; Pelaprat, Corine; Ruellet, Thierry; Sauriau, Pierre-Guy; Thorin, Sébastien

    2014-07-01

    Based on a parallel sampling conducted during autumn 2008, a comparative study of the intertidal benthic macrofauna among 10 estuarine systems located along the Channel and Atlantic coasts of France was performed in order to assess the level of fauna similarity among these sites and to identify possible environmental factors involved in the observed pattern at both large (among sites) and smaller (benthic assemblages) scales. More precisely this study focused on unraveling the observed pattern of intertidal benthic fauna composition and diversity observed at among-site scale by exploring both biotic and abiotic factors acting at the among- and within-site scales. Results showed a limited level of similarity at the among-site level in terms of intertidal benthic fauna composition and diversity. The observed pattern did not fit with existing transitional water classification methods based on fish or benthic assemblages developed in the frame of the European Water Framework Directive (WFD). More particularly, the coastal plain estuaries displayed higher among-site similarity compared to ria systems. These coastal plain estuaries were characterized by higher influence of river discharge, lower communication with the ocean and high suspended particulate matter levels. On the other hand, the ria-type systems were more dissimilar and different from the coastal plain estuaries. The level of similarity among estuaries was mainly linked to the relative extent of the intertidal “Scrobicularia plana-Cerastoderma edule” and “Tellina tenuis” or “Venus” communities as a possible consequence of salinity regime, suspended matter concentrations and fine particles supply with consequences on the trophic functioning, structure and organization of benthic fauna. Despite biogeographical patterns, the results also suggest that, in the context of the WFD, these estuaries should only be compared on the basis of the most common intertidal habitat occurring throughout all estuarine systems and that the EUNIS biotope classification might be used for this purpose. In addition, an original inverse relation between ?-diversity and area was shown; however, its relevance might be questioned.

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

    PubMed

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

    2011-04-01

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

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

    PubMed

    Quist, Michael C; Schultz, Randall D

    2014-09-01

    Fish and benthic macroinvertebrate assemblages often provide insight on ecological conditions for guiding management actions. Unfortunately, land use and management legacies can constrain the structure of biotic communities such that they fail to reflect habitat quality. The purpose of this study was to describe patterns in fish and benthic macroinvertebrate assemblage structure, and evaluate relationships between biota and habitat characteristics in the Chariton River system of south-central Iowa, a system likely influenced by various potential management legacies (e.g., dams, chemical removal of fishes). We sampled fishes, benthic macroinvertebrates, and physical habitat from a total of 38 stream reaches in the Chariton River watershed during 2002-2005. Fish and benthic macroinvertebrate assemblages were dominated by generalist species tolerant of poor habitat quality; assemblages failed to show any apparent patterns with regard to stream size or longitudinal location within the watershed. Metrics used to summarize fish assemblages and populations [e.g., presence-absence, relative abundance, Index of Biotic Integrity for fish (IBIF)] were not related to habitat characteristics, except that catch rates of piscivores were positively related to the depth and the amount of large wood. In contrast, family richness of benthic macroinvertebrates, richness of Ephemeroptera, Trichoptera, and Plecoptera taxa, and IBI values for benthic macroinvertebrates (IBIBM) were positively correlated with the amount of overhanging vegetation and inversely related to the percentage of fine substrate. A long history of habitat alteration by row-crop agriculture and management legacies associated with reservoir construction has likely resulted in a fish assemblage dominated by tolerant species. Intolerant and sensitive fish species have not recolonized streams due to downstream movement barriers (i.e., dams). In contrast, aquatic insect assemblages reflected aquatic habitat, particularly 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

  18. Spatial variation in density of stream benthic fishes in northern Hokkaido, Japan: does riparian vegetation affect fish density via food availability?

    Microsoft Academic Search

    Mikio Inoue; Masanori Nunokawa

    2005-01-01

    The densities of two benthic fishes, the Siberian stone loach (Noemacheilus barbatulus) and the wrinklehead sculpin (Cottus nozawae), and the biomass of their food resources (i.e., periphyton and benthic invertebrates) were compared between forest and grassland streams in northern Hokkaido, Japan, to examine whether riparian deforestation had positive effects on the benthic fishes via enhancement of food availability. The comparisons

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

    Microsoft Academic Search

    Rex L. Lowe; Robert W. Pillsbury

    1995-01-01

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

  20. Leaky Layers

    NSDL National Science Digital Library

    Paul J. Tackley

    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.

  1. Layered Liquids

    NSDL National Science Digital Library

    John Eichinger

    2009-05-30

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

  2. Benthic invertebrate communities in the fluctuating riverine habitat below Conowingo Dam. Final report

    SciTech Connect

    Janicki, A.J.; Ross, R.N.

    1982-03-01

    This report summarizes the findings of a benthic invertebrate study conducted on the Susquehanna River in the vicinity of the Conowingo Dam and hydroelectric generating station. Variations in the release of water from hydroelectric projects can strongly affect the availability of suitable habitats for downstream benthic invertebrates. To examine the extent of this problem in the Susquehanna River below Conowingo reservoir, basket samples were deployed along four transects in three habitats: constantly submerged channels, pools that become isolated at low flow, and areas exposed at low flow. Samplers were incubated for 3-week periods from June through October.

  3. The distribution and diversity of benthic macroinvertebrate fauna in Pondicherry mangroves, India

    PubMed Central

    2013-01-01

    Background Species distribution, abundance and diversity of mangrove benthic macroinvertebrate fauna and the relationships to environmental conditions are important parts of understanding the structure and function of mangrove ecosystems. In this study seasonal variation in the distribution of macrobenthos and related environmental parameters were explored at four mangrove stations along the Pondicherry coast of India, from September 2008 to July 2010. Multivariate statistical analyses, including cluster analysis, principal component analysis and non-multidimensional scales plot were employed to help define trophic status, water quality and benthic characteristic at the four monitoring stations. Results Among the 528 samples collected over 168 ha of mangrove forest 76 species of benthic macroinvertebrate fauna were identified. Macrofauna were mainly composed of deposit feeders, dominated numerically by molluscs and crustaceans. Statistical analyses yielded the following descriptors of benthic macroinvertebrate fauna species distribution: densities between 140–1113 ind. m-2, dominance 0.17-0.50, diversity 1.80-2.83 bits ind-1, richness 0.47-0.74 and evenness 0.45-0.72, equitability 0.38-0.77, berger parker 0.31-0.77 and fisher alpha 2.46-5.70. Increases of species diversity and abundance were recorded during the post monsoon season at station 1 and the lowest diversity was recorded at station 2 during the monsoon season. The pollution indicator organisms Cassidula nucleus, Melampus ceylonicus, Sphaerassiminea minuta were found only at the two most polluted regions, i.e. stations 3 and 4. Benthic macroinvertebrate fauna abundances were inversely related to salinity at the four stations, Based on Bray-Curtis similarity through hierarchical clustering implemented in PAST, it was possible to define three distinct benthic assemblages at the stations. Conclusions From a different multivariate statistical analysis of the different environmental parameters regarding species diversity and abundance of benthic macroinvertebrate fauna, it was found that benthic communities are highly affected by all the environmental parameters governing the distribution and diversity variation of the macrofaunal community in Pondicherry mangroves. Salinity, dissolved oxygen levels, organic matter content, sulphide concentration were the most significant parameters. PMID:23937801

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

    USGS Publications Warehouse

    Schemel, Laurence E.; Ota, A.Y.; Harmon, J.G.; Shay, J.M.; Adorado, R.N.

    1988-01-01

    Benthic macrofauna and ancillary data were collected during 1987 as part of the U.S. Geological Survey Regional Effects Monitoring Program in San Francisco Bay, California. Data were collected during five cruises at 2-month intervals from March through November. Benthic macrofauna for identification of species and sediment for size analysis were sampled at eight stations. Ancillary data, which consisted of salinity, temperature, dissolved-oxygen concentrations, and suspended sediment, were collected at 12 stations. Salinity and temperature were measured at three stations that coincided with continuous water quality monitors. Abundances and geographical distributions of a newly introduced species of clam were measured. (USGS)

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

    USGS Publications Warehouse

    Ferreira, Rodger F.; Green, D. Brady

    1977-01-01

    General comparisons were made between benthic organism samples collected in 1960-61 and 1972-73 from five sites in the Sacramento River between Red Bluff and Knights Landing, Calif. The composition of benthic organisms from both collection periods was similar. The 1972-73 data showed variable patterns in monthly changes at each site and downstream changes each month with number of organisms per square meter, number of taxa per square meter, and diversity index. Generally, the mean number of taxa per square meter and diversity index for all sampling periods were higher in the upper reach than the lower reach of the Sacramento River. (Woodard-USGS)

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

    PubMed

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

    2013-11-01

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

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

    SciTech Connect

    Chapman, P.M.

    1985-09-01

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

  8. Layered materials

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

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

  9. PIV measurements in the bottom boundary layer of the coastal ocean W.A.M. Nimmo Smith, P. Atsavapranee, J. Katz, T.R. Osborn

    E-print Network

    the sample areas to be aligned to the current, and measurements to be made up to 10 m above the bed. Sample and dissipation as well as a fit of the Kolmogorov ­5/3 spectral slope in the inertial range of the vertical velocity components, but it cannot scan the boundary layer. The BASS system (benthic acoustic stress sensor

  10. Benthic infaunal community structuring in an acidified tropical estuarine system

    PubMed Central

    2014-01-01

    Background Recent studies suggest that increasing ocean acidification (OA) should have strong direct and indirect influences on marine invertebrates. While most theory and application for OA is based on relatively physically-stable oceanic ecological systems, less is known about the effects of acidification on nearshore and estuarine systems. Here, we investigated the structuring of a benthic infaunal community in a tropical estuarine system, along a steep salinity and pH gradient, arising largely from acid-sulphate groundwater inflows (Sungai Brunei Estuary, Borneo, July 2011- June 2012). Results Preliminary data indicate that sediment pore-water salinity (range: 8.07 - 29.6 psu) declined towards the mainland in correspondence with the above-sediment estuarine water salinity (range: 3.58 – 31.2 psu), whereas the pore-water pH (range: 6.47- 7.72) was generally lower and less variable than the estuarine water pH (range: 5.78- 8.3), along the estuary. Of the thirty six species (taxa) recorded, the polychaetes Neanthes sp., Onuphis conchylega, Nereididae sp. and the amphipod Corophiidae sp., were numerically dominant. Calcified microcrustaceans (e.g., Cyclopoida sp. and Corophiidae sp.) were abundant at all stations and there was no clear distinction in distribution pattern along the estuarine between calcified and non-calcified groups. Species richness increased seawards, though abundance (density) showed no distinct directional trend. Diversity indices were generally positively correlated (Spearman’s rank correlation) with salinity and pH (p <0.05) and negatively with clay and organic matter, except for evenness values (p >0.05). Three faunistic assemblages were distinguished: (1) nereid-cyclopoid-sabellid, (2) corophiid-capitellid and (3) onuphid- nereid-capitellid. These respectively associated with lower salinity/pH and a muddy bottom, low salinity/pH and a sandy bottom, and high salinity/pH and a sandy bottom. However, CCA suggested that species distribution and community structuring is more strongly influenced by sediment particle characteristics than by the chemical properties of the water (pH and salinity). Conclusions Infaunal estuarine communities, which are typically adapted to survive relatively acidic conditions, may be less exposed, less sensitive, and less vulnerable than epibenthic or pelagic communities to further acidification of above-sediment waters. These data question the extent to which all marine infaunal communities, including oceanic communities, are likely to be affected by future global CO2-driven acidification. PMID:25396048

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

    NASA Astrophysics Data System (ADS)

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

    2003-04-01

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

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

    NASA Astrophysics Data System (ADS)

    McGillis, Wade

    2013-04-01

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

  13. 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.

  14. Lava Layers

    NSDL National Science Digital Library

    American Museum of Natural History

    2008-01-01

    In this activity (on pages 11-12 of PDF) learners create models of lava layers that have formed on the moon. The model is created by mixing a series of different colored vinegar with baking soda, then using colored play dough to cover wet areas where each color of "lava" erupted. Clear straws are pushed into the thickest part of the finished layers to get a "core sample." Groups can present their findings and a list of questions is provided to guide students to a deeper understanding. The activity is part of a larger curriculum based on a video on DVD, which you can request for free by emailing center@amnh.org.

  15. Modelling COD and N removal in the water and in the benthic biofilm for the River Wupper in Germany.

    PubMed

    Wichern, M; Kehl, O; Erbe, V; Luebken, M; Wilderer, P A

    2006-01-01

    The River Wupper, a tributary of the River Rhine, is at several locations influenced by anthropogenous nitrogen input, hydraulic structures, and influents from other tributaries. These influences have an impact both on the water quality and on the hydrodynamic conditions. The model approaches used for this article are based on work of Rauch et al. and the River Water Quality Model No. 1; they allow the simulation of the nitrogen conversion in the River Wupper. They are compatible with the activated sludge models and can thus be used also for integrated approaches. The calibration and validation of the model was realized using actual data of the River Wupper over a length of 60 km with one dam, 10 weirs, three wastewater treatment plants and 11 tributaries. The model considers the nitrogen conversion and COD removal and has a strong focus on biofilm processes in the benthic zone. Additional information is given about the sedimentation processes, the physical oxygen input processes, biofilm detachment processes, molecular diffusion, the influence of the laminar border layer and the changing of COD fractions and biofilm densities. PMID:16838700

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

    USGS Publications Warehouse

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

    2014-01-01

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

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

    Microsoft Academic Search

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

    2010-01-01

    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

  18. 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...

  19. Protection of marine benthic habitats in the Pacific islands. A case study of Guam

    Microsoft Academic Search

    Michael J Gawel

    1999-01-01

    Guam consists of a single main island surrounded by shallow fringing coral reefs. The marine species and ecology of Guam's coral reefs have been studied extensively, especially through programs of the University of Guam's Marine Laboratory. In addition to overfishing and destructive fishing practices, the marine benthic communities of Guam have been damaged by major storm waves; loss of corals

  20. Subtidal benthic macroinfaunal assemblages in tropical estuaries: generality amongst highly variable gradients.

    PubMed

    Barros, Francisco; de Carvalho, Gilson Correia; Costa, Yuri; Hatje, Vanessa

    2012-10-01

    South American estuaries are frequently not included in the search for general ecological models and studies dealing with biological assemblages in estuaries frequently do not sample the entire salinity gradient. We sampled three tropical estuaries, two times each, on ten stations distributed along each system. Six replicates were collected in each station for the benthic macroinfauna and sediment samples for grain size and inorganic contaminant analyses. There were finer sediments at the lower than at the upper estuarine portions. There was a decrease in the diversity, at family level, from marine to freshwater and the differences on the structure of the benthic assemblages were mostly spatial. In spite of the many different characteristics of the three estuaries (e.g. catchment size, pollution levels, proximity with the inner continental shelf) several consistent patterns of benthic macrofauna distribution along these systems were still observed. It suggested a general empirical model regarding the distribution of different benthic invertebrates along tropical salinity gradients which can be tested in different estuaries around the world. PMID:22975382

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

    E-print Network

    Wright, Dawn Jeannine

    density 3. Benthic Vegetation Abundance & Distribution Data West-East LandmarksExtent of coverage Assistance: Pat Clinton (CSC/Indus), Dynamac Corp. #12;Map Description Year Month Habitat Extent of coverage lower & mid estuary Intertidal submerged aquatic vegetation (seagrass & macroalgae) 1997, 1998, 2004

  2. 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 ...

  3. A Palaeozoic open shelf benthic assemblage in a protected marine environment1 Muriel Vidala,

    E-print Network

    Boyer, Edmond

    1 A Palaeozoic open shelf benthic assemblage in a protected marine environment1 2 Muriel Vidala environments is preserved in protected marine settings in the lower part of the Kermeur23 Formation (Armorican in low-energy open shelf settings. Their35 occurrence in a protected environment results from

  4. 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...

  5. Upper Cretaceous and lower Paleogene benthic foraminiferal paleoecology from north-eastern Tunisia: El Melah section

    Microsoft Academic Search

    N. Gallala; D. Zaghbib-Turki; M. M. Turki; I. Arenillas; J. A. Arz; E. Molina

    2009-01-01

    As an impact of the bolide and ejecta falls at the K\\/Pg boundary the planktonic Foraminifera have suffered sever mass extinction. However, no small Benthic Foraminifera species mass extinction at the K\\/Pg boundary has documented. Nevertheless many species have showed disturbance. The Maastrichtian assemblages may be different from those of the lower Paleogene by their species content, diversity and frequencies.

  6. First and last occurrences of Quaternary benthic foraminifera in the Gulf of Mexico: Relation to paleoceanography

    Microsoft Academic Search

    R. A. Denne; B. K. Sen Gupta

    1990-01-01

    The distribution record of benthic foraminifera in late Pleistocene and Recent sediments of the northwestern Gulf of Mexico indicates that stratigraphic occurrences of species are affected by paleoceanography Two species that are very common in the modern gulf, Bulimina alazanensis and Osangularia culter, were not present in the area during the last glacial, owing to the absence of Subantarctic Intermediate

  7. 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...

  8. Feedbacks between oceanic redox states and marine productivity: A model perspective focused on benthic phosphorus cycling

    Microsoft Academic Search

    K. Wallmann

    2003-01-01

    A new model for the marine cycles of particulate organic carbon (POC), oxygen, nitrate, and phosphorus has been developed and applied to explore the controls and constraints on marine productivity and nutrient inventories. The coupled benthic-pelagic model uses a new approach for the simulation of the reactive phosphorus turnover (Preac corresponding to the sum of organic P, authigenic P, and

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

    Microsoft Academic Search

    Lamberti

    1983-01-01

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

  10. 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...

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

    E-print Network

    McFall-Ngai, Margaret

    Protein synthesis in a solitary benthic cephalopod, the Southern dumpling squid (Euprymna tasmanica February 2009 Accepted 10 February 2009 Available online 15 February 2009 Keywords: Cephalopod Life rights reserved. 1. Introduction Cephalopod metabolism is protein-based: the capacity to assimilate

  12. Potential export of unattached benthic macroalgae to the deep sea through wind-driven Langmuir circulation

    Microsoft Academic Search

    H. M. Dierssen; R. C. Zimmerman; L. A. Drake; D. J. Burdige

    2009-01-01

    Carbon export to the deep sea is conventionally attributed to the sinking of open ocean phytoplankton. Here, we report a Langmuir supercell event driven by high winds across the shallow Great Bahama Bank that organized benthic non-attached macroalgae, Colpomenia sp., into visible windrows on the seafloor. Ocean color satellite imagery obtained before and after the windrows revealed a 588 km2

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

    E-print Network

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

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

    Microsoft Academic Search

    B. G. Hatcher

    1984-01-01

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

  15. A COMPARISON OF BENTHIC MACROINVERTEBRATE SAMPLING METHODS ON SELECTED LARGE RIVER TRIBUTARIES TO THE MISSISSIPPI

    EPA Science Inventory

    We compared three benthic macroinvertebrate sampling methods on the St. Croix, Wisconsin and Scioto Rivers in summer 2004 and 2005. EPA's newly developed, multi-habitat Large River Bioassessment Protocol (LR-BP) was compared to the multi-habitat method of the Minnesota Pollution...

  16. Recruitment and mortality of early post-settlement stages of benthic algae

    Microsoft Academic Search

    R. L. Vadas Sr; S. Johnson; T. A. Norton

    1992-01-01

    Four transitional life history stages are generally recognized for benthic marine algae. On the basis of differences in size, we propose two more: young germlings and young juveniles. Three of these (spores or zygotes, young germlings, and germlings) are considered early post-settlement (EPS) stages. Many of the available data on recruitment and mortality were not collected with EPS stages specifically

  17. Structure, dynamics and production of the benthic fauna in Lake Manitoba

    Microsoft Academic Search

    Claudiu Tudorancea; Roger H. Green; Judith Huebner

    1979-01-01

    The structure and diversity, including seasonal variation, and the energy budget of the benthic fauna in southern Lake Manitoba were studied and related to physical and chemical properties of the water and sediment. A total of 47 taxa were identified but 90 percent of individuals were represented by seven taxa (Candona rawsoni, Cytheromorpha fuscata, Pisidium spp., Amnicola limosa, Harnischia curtilamellata,

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

    Microsoft Academic Search

    G. L. Mackie

    1989-01-01

    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,

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

    E-print Network

    Zettler, Michael

    Benthic biodiversity indices versus salinity gradient in the southern Baltic Sea Michael L. Zettler *, Doris Schiedek, Bernd Bobertz Baltic Sea Research Institute, Seestr. 15, D-18119 Rostock, Germany Baltic Sea. The comparison of the three indices demonstrates that in the southern Baltic Sea

  20. 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...

  1. 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...

  2. Zebra mussels affect benthic predator foraging success and habitat choice on soft sediments

    Microsoft Academic Search

    M. A. Beekey; D. J. McCabe; J. E. Marsden

    2004-01-01

    The introduction of zebra mussels ( Dreissena spp.) to North America has resulted in dramatic changes to the complexity of benthic habitats. Changes in habitat complexity may have profound effects on predator-prey interactions in aquatic communities. Increased habitat complexity may affect prey and predator dynamics by reducing encounter rates and foraging success. Zebra mussels form thick contiguous colonies on both

  3. ROV observations of benthic fishes in the Northwind and Canada Basins, Arctic Ocean

    Microsoft Academic Search

    David L. Stein; James D. Felley; Michael Vecchione

    2005-01-01

    Abyssal and midslope Arctic benthic fishes were sampled nonquantitatively by still photography and videography from a remotely operated vehicle (ROV) between 13 August and 7 September 2002. Species diversity was low: only six putative species were seen, including Lycodes frigidus Collett 1879, Lycodes sp., Rhodichthys regina Collett 1879, Paraliparis bathybius (Collett 1879), Raja (Amblyraja) hyperborea Collett 1879, and Cottunculus species

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

    Microsoft Academic Search

    Donald M. McDowell; Robert J. Naiman

    1986-01-01

    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

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

    EPA Science Inventory

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

  6. Marine benthic habitat mapping of the West Arm, Glacier Bay National Park and Preserve, Alaska

    USGS Publications Warehouse

    Hodson, Timothy O.; Cochrane, Guy R.; Powell, Ross D.

    2013-01-01

    Seafloor geology and potential benthic habitats were mapped in West Arm, Glacier Bay National Park and Preserve, Alaska, using multibeam sonar, groundtruthed observations, and geological interpretations. The West Arm of Glacier Bay is a recently deglaciated fjord system under the influence of glacial and paraglacial marine processes. High glacially derived sediment and meltwater fluxes, slope instabilities, and variable bathymetry result in a highly dynamic estuarine environment and benthic ecosystem. We characterize the fjord seafloor and potential benthic habitats using the recently developed Coastal and Marine Ecological Classification Standard (CMECS) by the National Oceanic and Atmospheric Administration (NOAA) and NatureServe. Due to the high flux of glacially sourced fines, mud is the dominant substrate within the West Arm. Water-column characteristics are addressed using a combination of CTD and circulation model results. We also present sediment accumulation data derived from differential bathymetry. These data show the West Arm is divided into two contrasting environments: a dynamic upper fjord and a relatively static lower fjord. The results of these analyses serve as a test of the CMECS classification scheme and as a baseline for ongoing and future mapping efforts and correlations between seafloor substrate, benthic habitats, and glacimarine processes.

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

    E-print Network

    Chapman, Lauren J.

    turbidity, total dissolved solids (TDS), and conductivity values and low transparency values. Forest sites and boundary site groups generally exhibited low turbidity, TDS, and conductivity values and high water, water temperature, and pH were the most important factors predicting benthic macroinvertebrate

  8. Vertical distribution of benthic infauna in continental slope sediments off Cape Lookout, North Carolina

    NASA Astrophysics Data System (ADS)

    Blake, James A.

    The vertical distribution of 30 species of benthic infauna from continental slope (583-3000 m) sediments off Cape Lookout, North Carolina was closely correlated with feeding types. Carnivores, omnivores, filter feeders, and surface deposit feeders were mostly concentrated in the upper 0-2 cm of the cores. The depth distribution of subsurface deposit feeders was more variable, even among related taxa.

  9. Influence of drainage from old mine deposits on benthic macroinvertebrate communities in central Swedish streams

    Microsoft Academic Search

    Björn Malmqvist; Per-Ola Hoffsten

    1999-01-01

    We analysed the benthic macroinvertebrate species composition, taxonomic richness (as expected richness for 100 individuals), total abundance and biomass at 117 stream sites in the province of Dalarna. Partial least squares regression models were constructed from observations on undisturbed sites and used to predict these community parameters at sites exposed to elevated levels of copper, zinc, lead and cadmium resulting

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

    Microsoft Academic Search

    Fay Woodruff; Samuel M. Savin; Linda Abel

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

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

    Microsoft Academic Search

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

    1995-01-01

    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

  12. 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...

  13. Effects of PredatorPrey Interactions and Benthic Habitat Complexity on Selectivity of a Foraging Generalist

    E-print Network

    compared the prey selection of yellow perch (230­311 mm) foraging on common Great Lakes prey species--northern crayfish Orconectes virilis, round gobies Neogobius melanostomus, and alewives Alosa pseudoharengus in simple benthic habitat but selection for round gobies and against crayfish in complex habitat. Predator

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

    Microsoft Academic Search

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

    1977-01-01

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

  15. 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,...

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

    NSDL National Science Digital Library

    Amanda Meyer

    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.

  17. Modification of Lake Michigan Benthic Habitats by Zebra Mussels Primary Investigator: Stephen Lozano -NOAA GLERL

    E-print Network

    Modification of Lake Michigan Benthic Habitats by Zebra Mussels Primary Investigator: Stephen Overview Colonization by dreissenid mussels, Dreissena polymorpha (Zebra) and Dreissena bugensis (Quagga. Preliminary results suggest that zebra mussel populations on the lake bottom reflect sound in a unique way

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

    E-print Network

    Thuesen, Erik V.

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

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

    E-print Network

    Reynolds, John D.

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

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

    Microsoft Academic Search

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

    1996-01-01

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

  1. 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...

  2. Development and Policy Applications of the 2010 Benthic Habitat Map for Dry Tortugas National Park

    Microsoft Academic Search

    Robert J Waara

    2011-01-01

    In 2008 an initial benthic habitat map was completed by the contractor Avineon, Inc. The National Park Service South Florida \\/ Caribbean Network (SFCN) conducted an accuracy assessment of the map and found the overall habitat identification to be acceptable. However, upon further inspection, the soft-bottom habitat classifications displayed a relatively high level of accuracy, while the hard-bottom habitats were

  3. Triclosan exposure increases triclosan resistance and influences taxonomic composition of benthic bacterial communities.

    PubMed

    Drury, Bradley; Scott, John; Rosi-Marshall, Emma J; Kelly, John J

    2013-08-01

    Triclosan (TCS) is a broad-spectrum antimicrobial compound that is incorporated into numerous consumer products. TCS has been detected in aquatic ecosystems across the U.S., raising concern about its potential ecological effects. We conducted a field survey and an artificial stream experiment to assess effects of TCS on benthic bacterial communities. Field sampling indicated that TCS concentrations in stream sediments increased with degree of urbanization. There was significant correlation between sediment TCS concentration and the proportion of cultivable benthic bacteria that were resistant to TCS, demonstrating that the levels of TCS present in these streams was affecting the native communities. An artificial stream experiment confirmed that TCS exposure could trigger increases in TCS resistance within cultivable benthic bacteria, and pyrosequencing analysis indicated that TCS resulted in decreased benthic bacterial diversity and shifts in bacterial community composition. One notable change was a 6-fold increase in the relative abundance of cyanobacterial sequences and a dramatic die-off of algae within the artificial streams. Selection of cyanobacteria over algae could have significant implications for higher trophic levels within streams. Finally, there were no observed effects of TCS on bacterial abundance or respiration rates, suggesting that bacterial density and function were highly resilient to TCS exposure. PMID:23865377

  4. 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...

  5. 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....

  6. Abundance variations of benthic foraminifera in Upper Oligocene and Miocene strata of south Louisiana

    SciTech Connect

    Nunn, L.L.; Sen Gupta, B.K.

    1986-09-01

    Abundance variations of benthic foraminifera in some upper Oligocene and Miocene strata of south Louisiana were studied to evaluate trends of species dominance, associations, and faunal diversity. Fifty-seven well-cutting samples were obtained from eleven wells in six parishes: Vermilion, St. Mary, St. Martin, Assumption, Terrebonne, and Lafourche. In addition, core samples were obtained from two wells in Terrebonne Parish.

  7. Net spinning caddisflies as stream ecosystem engineers: the influence of Hydropsyche on benthic substrate stability

    Microsoft Academic Search

    B. J. CARDINALE; E. R. GELMANN; M. A. PALMER

    2004-01-01

    Summary 1. Organisms that physically modify or create habitat ( ecosystem engineers ) can have a profound influence on community and ecosystem dynamics. 2. Here evidence is presented that one of the most abundant and widely distributed lotic insects could act as an ecosystem engineer in streams by increasing the stability of benthic substrates during flooding. 3. Natural densities of

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

    E-print Network

    Stanley, Emily

    DOWNSTREAM BENTHIC RESPONSES TO SMALL DAM REMOVAL IN A COLDWATER STREAM CAILIN H. ORR,* STEVE J with an aging dam infrastructure has led to an increase in dam removals. However, ecological responses removals on downstream periphyton and macroinvertebrates in Boulder Creek, WI (USA). The dams were 180 m

  9. 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...

  10. 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

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

    E-print Network

    Wagner, Diane

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

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

    E-print Network

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

  13. The Role of Mercenaria mercenaria and Mytilus edulis in Coupling Benthic and Pelagic Nutrient Cycles

    E-print Network

    Vallino, Joseph J.

    Benthic and Pelagic Nutrient Cycles Kelsey A. Ream1 Mentor: Anne Giblin2 1 Departments of Biology, Mytilus edulis, nutrient cycling, phytoplankton clearance, respiration Introduction Knowledge of species the capabilities of native species to affect nutrient levels in the water column can be important for ensuring

  14. Nutrient exchange and ventilation of benthic gases across the continental shelf break

    E-print Network

    Mahadevan, Amala

    Nutrient exchange and ventilation of benthic gases across the continental shelf break S. A with idealized shelfslope geometry, wind forcing, and tracers to explore the interplay between the circulation and the biogeochemistry of the shelf and slope; the pathways that can transport nutrients from the deep ocean and from

  15. Benthic community dynamics during summer low?flows in two rivers of contrasting enrichment 2. Invertebrates

    Microsoft Academic Search

    Alastair M. Suren; Barry J. F. Biggs; Maurice J. Duncan; Liz Bergey; Paul Lambert

    2003-01-01

    We examined the effects of summer low?flow on invertebrate communities in two New Zealand rivers of contrasting enrichment and associated periphyton development. Quantitative benthic samples were collected and hydraulic measurements made from three runs in each river over a 6?week period. Although hydraulic conditions and time since last flood disturbance were similar in both rivers, invertebrate communities were dissimilar. This

  16. 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...

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

    E-print Network

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

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

    E-print Network

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

  19. Seafloor Geomorphology as Benthic Habitat. DOI: 2012 Elsevier Inc. All rights reserved.2012

    E-print Network

    Wright, Dawn Jeannine

    #12;Seafloor Geomorphology as Benthic Habitat. DOI: © 2012 Elsevier Inc. All rights reserved.20120058 58 Abstract We present the geomorphology of the Eastern Samoa Volcanic Province, covering 28,446km: bathymetry; geomorphology; submarine volcanism; seamounts; American Samoa; South Pacific; coral reefs; coral

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

    Microsoft Academic Search

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

    1997-01-01

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

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

    Microsoft Academic Search

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

    1995-01-01

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

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

    Microsoft Academic Search

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

    2012-01-01

    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

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

    Microsoft Academic Search

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

    2009-01-01

    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

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

    USGS Publications Warehouse

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

    2010-01-01

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

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

    Microsoft Academic Search

    Mikio Inoue; Masanobu Miyayoshi; Shin Sone

    2005-01-01

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

  6. An overview of the assessment of aquatic ecosystem health using benthic invertebrates

    Microsoft Academic Search

    Trefor B. Reynoldson; Janice L. Metcalfe-Smith

    1992-01-01

    Community structure or species composition of benthic invertebrates has frequently been used in environmental monitoring and assessment of aquatic systems. Three general approaches have been taken: the ‘saprobic’ approach, which requires detailed knowledge of taxonomy and is most effective in measuring impacts from sewage effluents; diversity indices, which do not require detailed knowledge of species requirements but ignore information provided

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

    E-print Network

    Sotka, Erik

    Benthic Herbivores are not Deterred by Brevetoxins Produced by the Red Tide Dinoflagellate Karenia brevis produce neurotoxic cyclic polyethers called brevetoxins. During and after a red tide bloom of Mexico blooms of the planktonic dinoflagellate Karenia brevis are among the oldest reported harmful algal

  8. Development of Benthic Indicators for Nearshore Coastal Waters of New Jersey - A REMAP Project

    EPA Science Inventory

    EPA's National Coastal Assessment (NCA) is providing the first complete, consistent dataset on the condition of benthic communities in the nation's estuaries. Prior to NCA, New Jersey based its evaluation of the ecological condition of its coastal waters solely on dissolved oxyg...

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

    USGS Publications Warehouse

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

    2010-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Yokoyama, Hisashi; Sakami, Tomoko; Ishihi, Yuka

    2009-04-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2003-12-01

    Benthic flux measurements of dissolved mercury species were made on sediment cores from Camp Far West Reservoir, a reservoir in which elevated mercury levels in sport fish had previously been documented. The reservoir is located downstream of historic hydraulic placer-gold mining and ore processing activities in the Bear River watershed of the northern Sierra Nevada. Field and laboratory studies were conducted in April and November of 2002 (one of the driest years on record for the area) to provide the first direct measurements of the benthic flux of dissolved mercury species between bottom sediment and the water column at three locations within the reservoir. Ancillary data, including nutrient and ligand fluxes, and benthic biological characterizations, were also gathered to provide a water-quality framework with which to interpret the mercury results. The following are the major observations made from interdependent physical, biological, and chemical data. Bottom water total mercury (HgT) concentrations ranged from 2.94 to 18.3 pM. Dissolved HgT benthic fluxes were generally higher in April than in November 2002 (based on site averages from replicate cores). HgT fluxes of 36.3 and -28.4 pmoles-m-2-h-1 were measured in cores from the deep site which was suboxic in November, contrasting with positive fluxes of 306 and 272 pmoles-m-2-h-1 at that site in April 2002 when the bottom water was oxic. All six measurements of HgT flux in April 2002 and five of six in November 2002 resulted in positive values (i.e., out of the sediment into the overlying water column). Consistent with benthic fluxes for HgT, dissolved MeHg fluxes were: (a) generally positive in April 2002, (b) negligible at all sites in November 2002, and (c) at least two orders of magnitude lower than total-mercury fluxes, roughly consistent with concentration differences between species. Observed concentration ranges for MeHg in bottom water ranged from less than the detection limit (0.20 pM) at the two 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.

  12. Quantum Layer Conjecture Quantum Layer Conjecture

    E-print Network

    Lu, Zhiqin

    Quantum Layer Conjecture Quantum Layer Conjecture Zhiqin Lu, UCI Last revised, March 21, 2014 #12;Quantum Layer Conjecture Introduction The concept of quantum layer was introduced in mesoscopic physics. A quantum layer is a kind of complete non-compact manifold with boundary. Figure : Picture of a quantum

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

    NASA Astrophysics Data System (ADS)

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

    2014-09-01

    Resuspended sediment can increase plankton biomass and the growth of bacteria, thus influencing the coastal planktonic microbial food web. But little is known about resuspension itself: is it a single massive change or a whole series of events and how does it affect the quantity and quality of resuspended prokaryotic cells? We simulated the sequential erosion of mud cores to better understand the fate and role of benthic prokaryotes resuspended in the water column. We analyzed the total, attached and free-living prokaryotic cells resuspended, their structure and the activities of their hydrolytic enzymes in terms of the biotic and abiotic factors that affect the composition of microphytobenthic biofilm. Free living prokaryotes were resuspended during the fluff layer erosion phase (for shear velocities below 5 cm · s- 1) regardless of the bed sediment composition. At the higher shear velocities, resuspended prokaryotes were attached to particulate matter. Free and attached cells are thus unevenly distributed, scattered throughout the organic matter (OM) in the uppermost mm of the sediment. Only 10-27% of the total cells initially resuspended were living and most of the Bacteria were Cyanobacteria and Gamma-proteobacteria; their numbers increased to over 30% in parallel with the hydrolytic enzyme activity at highest shear velocity. These conditions released prokaryotic cells having different functions that lie deep in the sediment; the most important of them are Archaea. Finally, composition of resuspended bacterial populations varied with resuspension intensity, and intense resuspension events boosted the microbial dynamics and enzyme activities in the bottom layers of sea water.

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Kim, Hae-Cheol; Montagna, Paul A.

    2009-08-01

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

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

    SciTech Connect

    Lamberti, G.A.

    1983-01-01

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

  17. Benthic-pelagic coupling: effects on nematode communities along southern European continental margins.

    PubMed

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

    2013-01-01

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

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

    PubMed Central

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

    2013-01-01

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

  19. Termination 1 timing in radiocarbon-dated regional benthic ?18O stacks

    NASA Astrophysics Data System (ADS)

    Stern, Joseph V.; Lisiecki, Lorraine E.

    2014-12-01

    Benthic ?18O changes are often assumed to be globally synchronous, but studies comparing 2-9 radiocarbon-dated records over the most recent deglaciation (Termination 1) have proposed differences in the timing of benthic ?18O change between the Atlantic and Pacific, intermediate and deep, and North and South Atlantic. Because of the relatively small number of records used in these previous studies, it has remained unclear whether these differences are local or regional in scale. Here we present seven regional benthic ?18O stacks for 0-40 kyr B.P. that include 252 records with independent regional age models constrained by 852 planktonic foraminiferal 14C dates from 61 of these cores. We find a 4000 year difference between the earliest termination onset in the intermediate South Atlantic at 18.5 (95% confidence interval: 17.9-19.0) kyr B.P. and the latest in the deep Indian at 14.5 (14.1-15.0) kyr B.P. The termination onset occurs at 17.5 kyr B.P. in the intermediate and deep North Atlantic, deep South Atlantic, and deep Pacific. However, throughout the termination deep North Atlantic benthic ?18O leads the deep Pacific by an average of 1000 year and a maximum of 1700 year. Additionally, the intermediate Pacific termination onset at 16.5 (16.1-16.9) kyr B.P. demonstrates that intermediate-depth benthic ?18O change was not globally synchronous. These regional stacks provide better age models than a global stack across Termination 1 and potentially important constraints on deglacial ocean circulation changes.

  20. Zebra mussels affect benthic predator foraging success and habitat choice on soft sediments.

    PubMed

    Beekey, M A; McCabe, D J; Marsden, J E

    2004-09-01

    The introduction of zebra mussels ( Dreissena spp.) to North America has resulted in dramatic changes to the complexity of benthic habitats. Changes in habitat complexity may have profound effects on predator-prey interactions in aquatic communities. Increased habitat complexity may affect prey and predator dynamics by reducing encounter rates and foraging success. Zebra mussels form thick contiguous colonies on both hard and soft substrates. While the colonization of substrata by zebra mussels has generally resulted in an increase in both the abundance and diversity of benthic invertebrate communities, it is not well known how these changes affect the foraging efficiencies of predators that prey on benthic invertebrates. We examined the effect of zebra mussels on the foraging success of four benthic predators with diverse prey-detection modalities that commonly forage in soft substrates: slimy sculpin ( Cottus cognatus), brown bullhead ( Ameirus nebulosus), log perch ( Percina caprodes), and crayfish ( Orconectes propinquus). We conducted laboratory experiments to assess the impact of zebra mussels on the foraging success of predators using a variety of prey species. We also examined habitat use by each predator over different time periods. Zebra mussel colonization of soft sediments significantly reduced the foraging efficiencies of all predators. However, the effect was dependent upon prey type. All four predators spent more time in zebra mussel habitat than in either gravel or bare sand. The overall effect of zebra mussels on benthic-feeding fishes is likely to involve a trade-off between the advantages of increased density of some prey types balanced against the reduction in foraging success resulting from potential refugia offered in the complex habitat created by zebra mussels. PMID:15278426

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

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

    NASA Astrophysics Data System (ADS)

    Takano, Yoshinori; Ohkouchi, Naohiko

    2013-04-01

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

  3. Mg isotope fractionation in biogenic carbonates of deep-sea coral, benthic foraminifera, and hermatypic coral.

    PubMed

    Yoshimura, Toshihiro; Tanimizu, Masaharu; Inoue, Mayuri; Suzuki, Atsushi; Iwasaki, Nozomu; Kawahata, Hodaka

    2011-11-01

    High-precision Mg isotope measurements by multiple collector inductively coupled plasma mass spectrometry were applied for determinations of magnesium isotopic fractionation of biogenic calcium carbonates from seawater with a rapid Mg purification technique. The mean ?(26)Mg values of scleractinian corals, giant clam, benthic foraminifera, and calcite deep-sea corals were -0.87‰, -2.57‰, -2.34‰, and -2.43‰, suggesting preferential precipitation of light Mg isotopes to produce carbonate skeleton in biomineralization. Mg isotope fractionation in deep-sea coral, which has high Mg calcite skeleton, showed a clear temperature (T) dependence from 2.5 °C to 19.5 °C: 1,000 × ln(?) = -2.63 (±0.076) + 0.0138 (±0.0051) × T(R(2) = 0.82, p < 0.01). The ?(26)Mg values of large benthic foraminifera, which are also composed of a high-Mg calcite skeleton, can be plotted on the same regression line as that for deep-sea coral. Since the precipitation rates of deep-sea coral and benthic foraminifera are several orders of magnitude different, the results suggest that kinetic isotope fractionation may not be a major controlling factor for high-Mg calcite. The Mg isotope fractionation factors and the slope of temperature dependence from deep-sea corals and benthic foraminifera are similar to that for an inorganically precipitated calcite speleothem. Taking into account element partitioning and the calcification rate of biogenic CaCO(3), the similarity among inorganic minerals, deep-sea corals, and benthic foraminiferas may indicate a strong mineralogical control on Mg isotope fractionation for high-Mg calcite. On the other hand, ?(26)Mg in hermatypic corals composed of aragonite has been comparable with previous data on biogenic aragonite of coral, sclerosponges, and scaphopad, regardless of species differences of samples. PMID:21805065

  4. Double Layers in Astrophysics

    NASA Technical Reports Server (NTRS)

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

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

    The benthic food web of the deep Faroe-Shetland Channel (FSC) was modelled by using the linear inverse modelling methodology. The reconstruction of carbon pathways by inverse analysis was based on benthic oxygen uptake rates, biomass data and transfer of labile carbon through the food web as revealed by a pulse-chase experiment. Carbon deposition was estimated at 2.2 mmol C m -2 d -1. Approximately 69% of the deposited carbon was respired by the benthic community with bacteria being responsible for 70% of the total respiration. The major fraction of the labile detritus flux was recycled within the microbial loop leaving merely 2% of the deposited labile phytodetritus available for metazoan consumption. Bacteria assimilated carbon at high efficiency (0.55) but only 24% of bacterial production was grazed by metazoans; the remaining returned to the dissolved organic matter pool due to viral lysis. Refractory detritus was the basal food resource for nematodes covering ?99% of their carbon requirements. On the contrary, macrofauna seemed to obtain the major part of their metabolic needs from bacteria (49% of macrofaunal consumption). Labile detritus transfer was well-constrained, based on the data from the pulse-chase experiment, but appeared to be of limited importance to the diet of the examined benthic organisms (<1% and 5% of carbon requirements of nematodes and macrofauna respectively). Predation on nematodes was generally low with the exception of sub-surface deposit-feeding polychaetes that obtained 35% of their energy requirements from nematode ingestion. Carnivorous polychaetes also covered 35% of their carbon demand through predation although the preferred prey, in this case, was other macrofaunal animals rather than nematodes. Bacteria and detritus contributed 53% and 12% to the total carbon ingestion of carnivorous polychaetes suggesting a high degree of omnivory among higher consumers in the FSC benthic food web. Overall, this study provided a unique insight into the functioning of a deep-sea benthic community and demonstrated how conventional data can be exploited further when combined with state-of-the-art modelling approaches.

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

    NASA Astrophysics Data System (ADS)

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

    2011-11-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-05-01

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

  8. Overview of the chemical ecology of benthic marine invertebrates along the western Antarctic peninsula.

    PubMed

    McClintock, James B; Amsler, Charles D; Baker, Bill J

    2010-12-01

    Thirteen years ago in a review that appeared in the American Zoologist, we presented the first survey of the chemical and ecological bioactivity of Antarctic shallow-water marine invertebrates. In essence, we reported that despite theoretical predictions to the contrary the incidence of chemical defenses among sessile and sluggish Antarctic marine invertebrates was widespread. Since that time we and others have significantly expanded upon the base of knowledge of Antarctic marine invertebrates' chemical ecology, both from the perspective of examining marine invertebrates in new, distinct geographic provinces, as well as broadening the evaluation of the ecological significance of secondary metabolites. Importantly, many of these studies have been framed within established theoretical constructs, particularly the Optimal Defense Theory. In the present article, we review the current knowledge of chemical ecology of benthic marine invertebrates comprising communities along the Western Antarctic Peninsula (WAP), a region of Antarctica that is both physically and biologically distinct from the rest of the continent. Our overview indicates that, similar to other regions of Antarctica, anti-predator chemical defenses are widespread among species occurring along the WAP. In some groups, such as the sponges, the incidence of chemical defenses against predation is comparable to, or even slightly higher than, that found in tropical marine systems. While there is substantial knowledge of the chemical defenses of benthic marine invertebrates against predators, much less is known about chemical anti-foulants. The sole survey conducted to date suggests that secondary metabolites in benthic sponges are likely to be important in the prevention of fouling by benthic diatoms, yet generally lack activity against marine bacteria. Our understanding of the sensory ecology of Antarctic benthic marine invertebrates, despite its great potential, remains in its infancy. For example, along the WAP, community-level non-consumptive effects occur when amphipods chemically sense fish predators and respond by seeking refuge in chemically-defended macroalgae. Such interactions may be important in releasing amphipods from predation pressure and facilitating their unusually high abundances along the WAP. Moreover, recent studies on the sensory biology of the Antarctic keystone sea star Odontaster validus indicate that chemotactile-mediated interactions between conspecifics and other sympatric predatory sea stars may have significant ramifications in structuring community dynamics. Finally, from a global environmental perspective, understanding how chemical ecology structures marine benthic communities along the WAP must increasingly be viewed in the context of the dramatic impacts of rapid climatic change now occurring in this biogeographic region. PMID:21558253

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

    E-print Network

    Filipsson, H. L.

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

  10. Benthic biological and biogeochemical patterns and processes across an oxygen minimum zone (Pakistan margin, NE Arabian Sea)

    E-print Network

    Levin, Lisa

    (Pakistan margin, NE Arabian Sea) Gregory L. Cowie a,Ã?, Lisa A. Levin b a The Sir John Murray Laboratories), and organic matter (OM) availability on benthic communities and processes across the Pakistan Margin

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

    PubMed

    Wu, Bin; Song, Jinming; Li, Xuegang

    2014-06-15

    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

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

    SciTech Connect

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

    1991-01-01

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

  13. Growth and uptake kinetics of nitrate and phosphate by benthic microalgae for phytoremediation of eutrophic coastal sediments.

    PubMed

    Kwon, Hyeong Kyu; Oh, Seok Jin; Yang, Han-Soeb

    2013-02-01

    In the present study, the effect of monochromatic light (blue, yellow and red) and mixed wavelength on the nutrient uptake and growth kinetics of benthic microalgae Achnanthes sp., Amphora sp., Navicula sp. and Nitzschia sp. were investigated. The maximum uptake rate (?max) for nitrate and phosphate obtained by short-term experiments were high in the order of blue, mixed, red, yellow wavelength, and among the 4 benthic microalgae, Nitzschia sp. was the highest ?max. The half-saturation constant (Ks) was higher than other taxon. The specific maximum growth rate (?max') and minimum cell quota (q0) for the nitrogen and phosphorus-limited condition, Nitzschia sp. showed the highest ?max' and q0 values among the 4 benthic microalgae. These results suggest that the benthic microalgae are adapted to high nutrient concentration. In particular, Nitzschia sp., which have a higher capability of storage and uptake, may be a useful species for phytoremediation. PMID:23262016

  14. Influence of hydraulic conditions over dunes on the distribution of the benthic macroinvertebrates in a large sand bed river

    NASA Astrophysics Data System (ADS)

    Amsler, Mario L.; Blettler, MartíN. C. M.; Ezcurra de Drago, InéS.

    2009-06-01

    This study aims to relate the flow structure over mobile dunes recorded on the channel bed of the Paraná River (Argentina) with the spatial distribution of the benthic macroinvertebrates. The following main conclusions have been obtained: (1) the dunes found in the active channel could be considered as hydraulic biotopes at a mesohabitat scale: the bed forms in the thalweg region are subjected to higher shear stresses with low benthic densities; (2) differences in benthic densities were also recorded at within-dunes microhabitat scales: the largest densities were found in the dune troughs where small bed shear stresses occur and minimum densities on the low stoss side of dunes where turbulent agitation near the bottom strongly disturb the bed particles; (3) superimposed dunes on larger dunes may be considered as another microhabitat of still smaller dimensions. Summarizing, multiscale approaches are needed if a comprehensive understanding linking hydrodynamics and morphodynamics processes with benthic ecology is intended.

  15. 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...

  16. 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 ...

  17. Relationships among levels of benthic vegetation and pore-water sulfides, burrowing shrimp and infaunal amphipods in Yaquina estuary, Oregon

    EPA Science Inventory

    Benthic amphipods are an important component of estuarine food webs, which in turn support ecological services provided by near shore commercial and recreational fisheries. In this study relationships among biological and geochemical aspects of the intertidal community were inve...

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

    E-print Network

    Tapia, Fabián

    2005-01-01

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

  19. The Cretaceous\\/Palaeogene (K\\/P) boundary at Ain Settara, Tunisia: restructuring of benthic foraminiferal assemblages

    Microsoft Academic Search

    Danuta Peryt; Laia Alegret; Eustoquio Molina

    2002-01-01

    Benthic foraminiferal assemblages, in contrast to planktic foraminifera, generally did not suffer mass extinctions at the Cretaceous\\/Palaeogene (K\\/P) boundary; extinctions were fewer in deeper water. However, the outer shelf, upper bathyal section at Ain Settara, Tunisia, records a dramatic change in the structure of benthic foraminiferal assemblages across the K\\/P boundary. At the level of extinction of planktic assemblages and

  20. The response of benthic foraminifera to the K–Pg boundary biotic crisis at Elles (northwestern Tunisia)

    Microsoft Academic Search

    Rodolfo Coccioni; Andrea Marsili

    2007-01-01

    The high-resolution quantitative study of benthic foraminifera from the Elles section (NW Tunisia) that contains one of the most complete Cretaceous–Paleogene (K–Pg) boundary transition and spans about 357 kyr provides detailed data on the palaeoenvironmental turnover across the K–Pg boundary. Benthic foraminifera indicate outer neritic-uppermost bathyal depths without perceivable bathymetrical changes throughout. Uppermost Maastrichtian assemblages are well preserved and highly diversified,

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

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

    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.

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

    PubMed

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

    2014-06-01

    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

  4. Relationships of sedimentation and benthic macroinvertebrate assemblages in headwater streams using systematic longitudinal sampling at the reach scale

    Microsoft Academic Search

    S. D. Longing; J. R. Voshell; C. A. Dolloff; C. N. Roghair

    2010-01-01

    Investigating relationships of benthic invertebrates and sedimentation is challenging because fine sediments act as both natural\\u000a habitat and potential pollutant at excessive levels. Determining benthic invertebrate sensitivity to sedimentation in forested\\u000a headwater streams comprised of extreme spatial heterogeneity is even more challenging, especially when associated with a background\\u000a of historical and intense watershed disturbances that contributed unknown amounts of fine

  5. Benthic invertebrates of fixed sites in the western Lake Michigan drainages, Wisconsin and Michigan, 1993-95

    USGS Publications Warehouse

    Lenz, Bernard N.; Rheaume, S.J.

    2000-01-01

    This report describes the variability in family-level benthic-invertebrate population data and the reliability of the data as a water-quality indicator for 11 fixed surface-water sites in the Western Lake Michigan Drainages study area of the National Water-Quality Assessment Program. Benthic-invertebrate-community measures were computed for the following: number of individuals, Hilsenhoff's Family-Level Biotic Index, number and percent EPT (Ephemeroptera, Plecoptera, and Tricoptera), Margalef's Diversity Index, and mean tolerance value. Relations between these measures and environmental setting, habitat, and of chemical water quality are examined. Benthic-invertebrate communities varied greatly among fixed sites and within individual streams among multiple-reach and multiple-year sampling. The variations between multiple reaches and years were sometimes larger than those found between different fixed sites. Factors affecting benthic invertebrates included both habitat and chemical quality. Generally, fixed-site streams with the highest diversity, greatest number of benthic invertebrates, and those at which community measures indicated the best water quality also had the best habitat and chemical quality. Variations among reaches are most likely related to differences in habitat. Variations among years are most likely related to climatic changes, which create variations in flow and/or chemical quality. The variability in the data analyzed in this study shows how benthic invertebrates are affected by differences in both habitat and water quality, making them useful indicators of stream health; however, a single benthic-invertebrate sample alone cannot be relied upon to accurately describe water quality of the streams in this study. Benthic- invertebrate data contributed valuable information on the biological health of the 11 fixed sites when used as one of several data sources for assessing water quality.

  6. New records of benthic marine algae and Cyanobacteria for Costa Rica, and a comparison with other Central American countries

    NASA Astrophysics Data System (ADS)

    Bernecker, Andrea; Wehrtmann, Ingo S.

    2009-09-01

    We present the results of an intensive sampling program carried out from 2000 to 2007 along both coasts of Costa Rica, Central America. The presence of 44 species of benthic marine algae is reported for the first time for Costa Rica. Most of the new records are Rhodophyta (27 spp.), followed by Chlorophyta (15 spp.), and Heterokontophyta, Phaeophycea (2 spp.). Overall, the currently known marine flora of Costa Rica is comprised of 446 benthic marine algae and 24 Cyanobacteria. This species number is an under estimation, and will increase when species of benthic marine algae from taxonomic groups where only limited information is available (e.g., microfilamentous benthic marine algae, Cyanobacteria) are included. The Caribbean coast harbors considerably more benthic marine algae (318 spp.) than the Pacific coast (190 spp.); such a trend has been observed in all neighboring countries. Compared to other Central American countries, Costa Rica has the highest number of reported benthic marine algae; however, Panama may have a similarly high diversity after unpublished results from a Rhodophyta survey (Wysor, unpublished) are included. Sixty-two species have been found along both the Pacific and Caribbean coasts of Costa Rica; we discuss this result in relation to the emergence of the Central American Isthmus.

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

    NASA Astrophysics Data System (ADS)

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

    2005-05-01

    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.

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

    USGS Publications Warehouse

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

    2014-01-01

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

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

    PubMed

    Li, Tao; Xiang, Rong; Li, Tuanjie

    2013-10-15

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

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

    PubMed

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

    2014-10-15

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

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

    USGS Publications Warehouse

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

    1989-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2014-06-01

    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.

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

    PubMed Central

    Vincent, Warwick F.; Downes, Malcolm T.

    1981-01-01

    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

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

    USGS Publications Warehouse

    Waller, Bradley G.

    1976-01-01

    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.

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

    NASA Technical Reports Server (NTRS)

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

    1980-01-01

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

  16. Quantifying the Impacts of Forest Harvesting on Benthic Macroinvertebrate Community Structure in Western Canada

    NASA Astrophysics Data System (ADS)

    Barkway, M. P.; Spence, J. R.

    2005-05-01

    Benthic macroinvertebrates can be excellent indicators of stream condition and have been used to effectively assess stream health in disturbed watersheds. Previous works have demonstrated that community composition and density are significantly and predictably altered by disturbance. This study quantifies the impacts of forest harvesting on invertebrate community structure in headwater streams of west-central Alberta, Canada, using both parametric statistical techniques and a multimetric index. Invertebrates were sampled from six streams, three of which were harvested and three of which were undisturbed, in the summer of 2004. Preliminary analyses suggest that forest harvesting does not have a significant effect on benthic macroinvertebrate community structure, although relative densities of component groups may be altered. To date, stream monitoring programs in this region have focused primarily on physical habitat and water chemistry. However, our results demonstrate that the examination and inclusion of these biological measures may offer a new and wider perspective to stream monitoring and sustainable forestry programs.

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

    PubMed

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

    2013-07-15

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

  18. Metal leaching, acidity, and altitude confine benthic macroinvertebrate community composition in Andean streams.

    PubMed

    Loayza-Muro, Raúl A; Duivenvoorden, Joost F; Kraak, Michiel H S; Admiraal, Wim

    2014-02-01

    Andean streams drain metal-rich bedrock and are subjected to an extreme altitude gradient, which may create highly selective conditions for life. The aim of the present study was to evaluate the combined effects of metals and altitude on benthic macroinvertebrate community composition in Andean streams. Metal-rich sites were characterized by high metal concentrations and low pH, and high-altitude sites were characterized by high ultraviolet-B radiation and low concentrations of dissolved organic matter. Canonical correspondence analysis indicated that the patterns in faunal composition were best explained by metals followed by altitude, with dipterans and collembolans occurring mostly under harsh conditions of high altitude and high metal levels. Interaction between metals and altitude was most evident at metal-rich sites. It is suggested that in Andean streams, metal leaching from igneous rock and altitude may be important factors confining benthic macroinvertebrate communities, reducing their numbers and changing their composition toward specialized taxa. PMID:24150981

  19. Benthic macrofauna of the New York Bight, 1979-89. Technical report

    SciTech Connect

    Reid, R.N.; Radosh, D.J.; Frame, A.B.; Fromm, S.A.

    1991-12-01

    The benthic macrofauna of the New York Bight has been monitored extensively, primarily to determine trends over space and time in biological effects of waste inputs. In the present study, from 44 to 48 stations were sampled each summer from 1980-1985. Data from other Bight benthic studies are included to extend the temporal coverage from 1979 to 1989. Numbers of species and amphipods per sample, taken as relatively sensitive indicators of environmental stress, showed consistent spatial patterns. Lowest values were found in the Christiaensen Basin and other inshore areas, and numbers increased toward the outermost shelf and Hudson Shelf Valley stations. Preliminary data from a more recent study suggest numbers of species increased again between 1986 and 1989. Causes of the faunal changes are not obvious; some possibilities, including increasing effects of sewage sludge or other waste inputs, natural factors, and sampling artifacts, are discussed.

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

    USGS Publications Warehouse

    Hudson, Patrick L.; Nichols, S. Jerrine

    1986-01-01

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

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

    SciTech Connect

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

    1995-12-31

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

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

    SciTech Connect

    Berkman, P.A.

    1992-03-01

    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.

  3. Variations of an oxygen minimum zone in the Okhotsk Sea over the last glacial-interglacial cycle as recorded by benthic foraminiferal and sedimentological data

    NASA Astrophysics Data System (ADS)

    Bubenshchikova, N.; Nuernberg, D.; Tiedemann, R.; Lembke-Jene, L.

    2011-12-01

    At present, the Okhotsk Sea contributes to ventilation of intermediate NW-Pacific via production of the oxygenated Okhotsk Sea Intermediate Water (OSIW: ~200-800 m). In the Okhotsk Sea, oxygen minimum zone appears as water layer between ~800 and 1500 m water depths with oxygen contents 0.3-1.5 ml/l. The paleoreconstructions of the OSIW production and the OMZ intensity in the Okhotsk Sea are important to understand the glacial-interglacial variations of oxygenation / ventilation of intermediate NW-Pacific. This study presents high-resolution benthic foraminiferal and sedimentological data for the last 115 ka of the IMAGES core MD01-2415 (Figure 1). The resulting reconstructions of the OMZ intensity for core MD01-2415 are compared with those for the KOMEX cores: LV28-2-4, LV28-40-5 and LV28-43-5 covering the last 52, 80 and 46 ka, respectively. To reconstruct intensity of the OMZ, we applied downcore distributions of the relative abundance (%) and accumulation rate (AR, sp. cm/kyr) of the dominant benthic foraminifera and assemblages indicative of the different bottom water oxygenation (Figure 1). The Dysoxic (0.1-0.3 ml/l), Suboxic (0.3-1.5 ml/l) and Oxic (1.5-6 ml/l) assemblages were obtained by grouping of all species of cores. Additional proxies included the sediment color* b, magnetic susceptibility, the percentage and AR of total organic carbon, calcium carbonate and biogenic opal for cores under study. We discuss probable causes of the reconstructed intensification of the Okhotsk Sea OMZ during the Termination I - Holocene (with maximum in the Preboreal) and the OMZ weakening during the Marine Isotope Stages 2-5d.

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

    PubMed Central

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

    2014-01-01

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

  5. Classifying benthic biotopes on sub-tropical continental shelf reefs: How useful are abiotic surrogates?

    NASA Astrophysics Data System (ADS)

    Richmond, Sarah; Stevens, Tim

    2014-02-01

    Biodiversity of marine areas beyond the reach of conventional diving technology (>30 m) is poorly known, yet subjected to increasing stresses from expanding recreational and commercial fishing, minerals exploration and other anthropogenic influences. In part, resource managers address this by using abiotic surrogates for patterns of biodiversity in planning marine protected areas or other management measures. However, the efficacy of these surrogates varies from place to place, and is often not quantified at the scale used by MPA designers and managers. This study surveyed and classified benthic assemblages of continental shelf rocky reefs across three depth categories from 30 to 70 m, using a suspended HD camera array, which is both non-destructive and cost-effective compared to any other methods of sampling at these depths. Five distinct benthic biotopes were defined, characterised primarily by variations in abundances of sea whips, sponges, kelp, and urchins. Derived patterns of benthic assemblage structure were compared to abiotic surrogates available at the scale (local) used in MPA planning. The individual factors with most influence on the classification were recreational fishing pressure, water temperature at the bottom, and distance from nearest estuary. The best combination of abiotic surrogates had a relatively strong relationship with the benthic assemblage, explaining 42% of the variation in assemblage structure (BIOENV ? = 0.65), however the performance of a classification based on commonly used physical surrogates was relatively poor, explaining only 22% of variation. The results underline the limitations of using abiotic variables for habitat mapping at the local scale, and the need for robust surveys to quantify patterns of biodiversity.

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

    NASA Astrophysics Data System (ADS)

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

    2013-01-01

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

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

    Microsoft Academic Search

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

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

  8. Oceanographic characteristics of the habitat of benthic fish and invertebrates in the Beaufort Sea

    Microsoft Academic Search

    Elizabeth Logerwell; Kimberly Rand; Thomas J. Weingartner

    We relate the spatial variability in the distribution of benthic taxa of the Beaufort Sea to oceanographic characteristics\\u000a of their habitat with the goal of illustrating potential mechanisms linking climate change to Arctic marine communities. Offshore\\u000a fish of the Beaufort Sea have not been surveyed since 1977 and no synchronous measures of fish distribution and the oceanographic\\u000a characteristics of their

  9. Benthic Macroinvertebrate Responses to Increasing Levels of Cattle Grazing in Blue Ridge Mountain Streams, Virginia, USA

    Microsoft Academic Search

    Amy Braccia; J. Reese Voshell Jr

    2007-01-01

    The relationship between benthic macroinvertebrate assemblages and cattle density was assessed from fall 2002 through spring\\u000a 2004 in five small streams that represented a gradient of cattle grazing intensity. All study stream reaches were in pasture\\u000a with no woody riparian vegetation, but varied in the intensity of cattle grazing (0 cattle ha?1 at site 1 to 2.85 cattle ha?1 at

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

    USGS Publications Warehouse

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

    2009-01-01

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

  11. Effects of 4-nonylphenol on benthic macroinvertebrates and insect emergence in littoral enclosures

    SciTech Connect

    Schmude, K.L.; Liber, K.; Corry, T.D. [Univ. of Wisconsin, Superior, WI (United States). Lake Superior Research Inst.; Stay, F.S. [Environmental Protection Agency, Duluth, MN (United States). Mid-Continent Ecology Div.

    1999-03-01

    The effect of 4-nonylphenol (NP) on benthic, freshwater macroinvertebrates in littoral enclosures was evaluated over a 2-year period. Enclosures received 11 NP applications, 48 h apart, with nominal rates of 3, 30, 100, and 300 {micro}g/L. Mean measured peak concentrations in integrated water column samples over the 20-d application period were 5 {+-} 4, 23 {+-} 11, 76 {+-} 21, and 243 {+-} 41 {micro}g/L NP. Concentrations of NP in the water column decreased rapidly after the last application. Maximum NP concentrations measured in sediments, pore water, and macrophytes of a 300-{micro}g/L enclosure were 27.4 mg/kg, 29.9 {micro}g/L, and 89.6 mg/kg, respectively. The most abundant macroinvertebrate groups, Chironomidae, Oligochaeta, and Mollusca, decreased in abundance after application. Effects on Mollusca were the most severe. Their numbers were significantly reduced at the highest treatment throughout most of the study. Oligochaetes and chironomids were also significantly reduced at the highest treatment, but populations recovered within 6 weeks. Snails and naidid oligochaetes were slightly affected at the second highest treatment (76 {+-} 21 {micro}g/L NP). Insect emergence was reduced during and immediately post-application, but the effects were likely caused or compounded by a surfactant sheen on the surface of the water that interfered with emergence and/or oviposition. The observed effects on the benthic community were most likely due to exposure from the water, although more persistent macrophyte-associated residues may have contributed to effects on Gastropoda, Naididae, and Tanytarsini. Macrophyte-associated NP residues may pose a small risk to benthic organisms, but it is probably minor compared to water exposures. The no-observed and lowest-observed-effect concentration for the benthic community was 23 {+-} 11 and 76 {+-} 21 {micro}g/L NP, respectively.

  12. Effects of Karenia brevis on clearance rates and bioaccumulation of brevetoxins in benthic suspension feeding invertebrates.

    PubMed

    Echevarria, Michael; Naar, Jerome P; Tomas, Carmelo; Pawlik, Joseph R

    2012-01-15

    Blooms of the toxic alga Karenia brevis occur along coastlines where sessile suspension feeding invertebrates are common components of benthic communities. We studied the effects of K. brevis on four benthic suspension feeding invertebrates common to the coast of the SE United States: the sponge Haliclona tubifera, the bryozoan Bugula neritina, the bivalve Mercenaria mercenaria, and the tunicate Styela plicata. In controlled laboratory experiments, we determined the rate at which K. brevis was cleared from the seawater by these invertebrates, the effect of K. brevis on clearance rates of a non-toxic phytoplankton species, Rhodomonas sp., and the extent to which brevetoxins bioaccumulated in tissues of invertebrates using an enzyme-linked immunosorbent assay (ELISA). All four invertebrate species cleared significant quantities of K. brevis from seawater, with mean clearance rates ranging from 2.27 to 6.71 L g h?¹ for H. tubifera and S. plicata, respectively. In the presence of K. brevis, clearance rates of Rhodomonas sp. by B. neritina and S. plicata were depressed by 75% and 69%, respectively, while clearance rates by H. tubifera and M. mercenaria were unaffected. Negative effects of K. brevis were impermanent; after a recovery period of 13 h, B. neritina and S. plicata regained normal clearance rates. All four invertebrates accumulated high concentrations of brevetoxin after a 4h exposure to K. brevis, but when animals were transferred to filtered seawater for 15 h after exposure, brevetoxin concentrations in the tissues of H. tubifera and B. neritina decreased by ?80%, while there was no change in toxin concentration in the tissues of S. plicata and M. mercenaria. High cell concentrations of K. brevis may cause a suppression of clearance rates in benthic suspension feeding invertebrates, resulting in a positive feedback for bloom formation. Also, high concentrations of toxin may accumulate in the tissues of benthic suspension feeding invertebrates that may be transferred to higher-level consumers. PMID:22115907

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

    NASA Astrophysics Data System (ADS)

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

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

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

    Microsoft Academic Search

    Daniele Longhi; Marco Bartoli; Pierluigi Viaroli

    2008-01-01

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

  15. The Effects of a Dredge Excavation Pit on Benthic Macrofauna in Offshore Louisiana

    Microsoft Academic Search

    Terence A. Palmer; Paul A. Montagna; Robert B. Nairn

    2008-01-01

    Over two years after the original creation of a sand excavation pit 8 km off the Louisiana coast, benthic macrofauna communities\\u000a and sedimentary characteristics are still effected. Macrofaunal communities inside the pit had lower abundance, biomass, and\\u000a diversity than communities outside the pit. This difference, however, was only significant with some of the stations outside\\u000a the pit. Results from multi-dimensional scaling

  16. Benthic community structure in stands of Typha angustifolia and herbicide-treated and untreated Phragmites australis

    Microsoft Academic Search

    Amy E. Kulesza; Joseph R. Holomuzki; David M. Klarer

    2008-01-01

    We compared benthic community structure among stands of Typha angustifolia (narrow-leaf cattail) and herbicide-treated (Glypro) and untreated Phragmites australis (common reed) over two summers in a Lake Erie coastal wetland (i.e., drowned river mouth). Both macrophytes are invasives,\\u000a but only Phragmites is currently controlled by herbicides because of its reputed “undesirable” effects on wetland community structure and function.\\u000a Macroinvertebrate diversity

  17. Invasive reed effects on benthic community structure in Lake Erie coastal marshes

    Microsoft Academic Search

    Joseph R. HolomuzkiDavid; David M. Klarer

    2010-01-01

    We examined how dominance (% canopy cover) and invasion history of common reed, Phragmites australis, affected benthic macroinvertebrate diversity and density in 8 marshes along Lake Erie’s southern shoreline. We also compared\\u000a macroinvertebrate densities among patches (0.25 m2) of reed, cattail (Typha spp.), and native flora (e.g., Sagittaria, Sparganium) and epiphytic algal communities on submerged stems of reed and cattail. Narrow-leaf

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

    Microsoft Academic Search

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

    1989-01-01

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

  19. The potential of large-scale open-sea cultivation of benthic algae

    Microsoft Academic Search

    H. J. Humm

    1979-01-01

    There is an area of open water about 200 miles long and 20 miles wide along the Florida Gulf coast that is eminently adapted to large-scale mariculture of tropical benthic algae. It is suggested that this is a unique area for the development of a large-scale system of planting, harvesting, and processing certain fast-growing tropical marine algae of value as

  20. Rhythmic behaviour of marine benthopelagic species and the synchronous dynamics of benthic communities

    NASA Astrophysics Data System (ADS)

    Aguzzi, Jacopo; Sbragaglia, Valerio; Tecchio, Samuele; Navarro, Joan; Company, Joan B.

    2015-01-01

    Light-intensity cycles drive the relentless motion of species in the oceans, and water column migrants may cyclically make contact with the seabed, hence influencing the temporal dynamism of benthic ecosystems. The influence of light on this process remains largely unknown to date. In this study, we focus on the occurrence of day-night changes in benthic communities on the western Mediterranean continental shelf (100 m depth) and slope (400 m depth) as a potential result of a behaviourally sustained benthopelagic coupling. We analysed fluctuations in species abundance based on trawling at hourly intervals over a 4-day period as a proxy of activity rhythms at the seabed. We also measured light in situ to assess how the depth-related decrease of its intensity influences species rhythms and the occurrence of the putative benthopelagic synchronisation. Temporal similarities in the catch patterns for different species were screened by dendrogram analysis. On the continental shelf, species performing diel migrations (i.e., over a 24 h period) that were either vertical (i.e., benthopelagic) or horizontal across depths (i.e., nektobenthic) clustered together separately from the more sedentary endobenthic and epibenthic species. At the same depth, waveform analysis showed a significant diurnal increase in the catch of water column species and benthic species at night. Such coupling was absent on the continental slope, where light intensity was several orders of magnitude lower than that on the shelf. Our data indicate that diel activity rhythms, which are well known for vertical pelagic migrators, are also evident in the benthos. We discuss the role of light as a major evolutionary driver shaping the composition and biodiversity of benthic communities via visual predation.