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Sample records for benthic zone

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

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    N. Glock

    2012-12-01

    Full Text Available 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

  2. Benthic phosphorus cycling in the Peruvian oxygen minimum zone

    Science.gov (United States)

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

    2016-03-01

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

  3. Benthic phosphorus cycling in the Peruvian oxygen minimum zone

    DEFF Research Database (Denmark)

    Lomnitz, Ulrike; Sommer, Stefan; Dale, Andrew W.;

    2016-01-01

    (TPP = POP + PIP) ratio was close to Redfield in the water column (103 ± 9) and in sediment samples (102 ± 15). This suggests that the relative burial efficiencies of POC and TPP are similar under low-oxygen conditions and that the sediments underlying the anoxic waters on the Peru margin are not...... depleted in P compared to Redfield. Benthic fluxes of dissolved P were extremely high (up to 1.04 ± 0.31 mmol m-2 d-1), however, showing that a lack of oxygen promotes the intensified release of dissolved P from sediments, whilst preserving the POC/TPP burial ratio. Benthic dissolved P fluxes were always...... higher than the TPP rain rate to the seabed, which is proposed to be caused by transient P release by bacterial mats that had stored P during previous periods when bottom waters were less reducing. At one station located at the lower rim of the OMZ, dissolved P was taken up by the sediments, indicating...

  4. Denitrification, nitrate turnover, and aerobic respiration by benthic foraminiferans in the oxygen minimum zone off Chile

    DEFF Research Database (Denmark)

    Høgslund, Signe; Revsbech, Niels Peter; Cedhagen, Tomas;

    2008-01-01

    Population density, nitrate turnover, and oxygen respiration of benthic foraminiferans were investigated in the oxygen minimum zone (OMZ) off the Chilean coast. Live foraminiferans were found predominantly in the upper 3 mm of the sediment, and the nitrate accumulating species Nonionella cf. stella...... and Stainforthia sp. dominated with a combined standing stock of 2.0 × 106 Rose Bengal stained specimens m−2. The rate of denitrification in cells of N. cf. stella analyzed with nitrous oxide microsensors during acetylene inhibition was 84 ± 33 pmol C individual−1 d−1. Multiplied with the standing...... stock of N. cf. stella and Stainforthia sp. this yielded a minimum benthic denitrification rate of 173 μmol N m−2 d−1 by foraminiferans. Foraminiferal denitrification, which seemed to account for almost all benthic denitrification at the investigated site will be overlooked by most conventional methods...

  5. Distribution of benthic foraminifera within oxygen minima zone, off central west coast, India

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumder, A.; Henriques, P.J.; Nigam, R.

    A total of 128 surface sediment samples (76 grab and 52 core top samples) were analyzed for benthic foraminiferal contents from the region off Goa, India in the eastern Arabian Sea upto a water depth of 3300 m. 195 species of benthic foraminifera...

  6. Depletion of oxygen, nitrate and nitrite in the Peruvian oxygen minimum zone cause an imbalance of benthic nitrogen fluxes

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    Sommer, S.; Gier, J.; Treude, T.; Lomnitz, U.; Dengler, M.; Cardich, J.; Dale, A. W.

    2016-06-01

    Oxygen minimum zones (OMZ) are key regions for fixed nitrogen loss in both the sediments and the water column. During this study, the benthic contribution to N cycling was investigated at ten sites along a depth transect (74-989 m) across the Peruvian OMZ at 12°S. O2 levels were below detection limit down to ~500 m. Benthic fluxes of N2, NO3-, NO2-, NH4+, H2S and O2 were measured using benthic landers. Flux measurements on the shelf were made under extreme geochemical conditions consisting of a lack of O2, NO3- and NO2- in the bottom water and elevated seafloor sulphide release. These particular conditions were associated with a large imbalance in the benthic nitrogen cycle. The sediments on the shelf were densely covered by filamentous sulphur bacteria Thioploca, and were identified as major recycling sites for DIN releasing high amounts of NH4+up to 21.2 mmol m-2 d-1 that were far in excess of NH4+ release by ammonification. This difference was attributed to dissimilatory nitrate (or nitrite) reduction to ammonium (DNRA) that was partly being sustained by NO3- stored within the sulphur oxidizing bacteria. Sediments within the core of the OMZ (ca. 200-400 m) also displayed an excess flux of N of 3.5 mmol m-2 d-1 mainly as N2. Benthic nitrogen and sulphur cycling in the Peruvian OMZ appears to be particularly susceptible to bottom water fluctuations in O2, NO3- and NO2-, and may accelerate the onset of pelagic euxinia when NO3- and NO2- become depleted.

  7. Benthic fauna of mangrove environment

    Digital Repository Service at National Institute of Oceanography (India)

    Parulekar, A.H.

    distribution of benthic communities in mangrove environment is governEd. by tidal amplitude, light penetration, nature of substratum and distance from the sea. The littoral zone, neritic zone, Barnacle-oyster zone, Uca zone, Polychaeta zone have been delineated...

  8. Benthic Macrofaunal Assemblage in the Arid Zone Mangroves of Gulf of Kachchh - Gujarat

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    The total benthic macrofauna consisting of 62 species in 5 groups, viz. crustaceans (18), gastropods (17), bivalves (16), polychaetes (9) and fishes (2), was recorded in western Kachchh mangroves near Gujarat. The population densities of benthic macrofauna ranged from 424 to 2393 ind.m-2, the diversity ranged from 1.84 to 2.45 bits ind.-1, the richness varied between 0.82 and 0.98, and the evenness varied between 0.64 and 0.81. Two maximum diversity values were recorded during winter and summer. The salinity ranged from 34 to 44, temperature varied between 17 and 37 ℃, and the acidity ranged from 7 to 8.9.

  9. Habitat heterogeneity and its influence on benthic biodiversity in oxygen minimum zones

    Digital Repository Service at National Institute of Oceanography (India)

    Gooday, A.J.; Bett, B.J.; Escobar, E.; Ingole, B.S.; Levin, L.A.; Neira, C.; Raman, A.V.; Sellanes, J.

    and quality are unclear, but probably related to differences in the 5 activities of benthic communities. On the Oman Margin, Smallwood et al. (1999) reported that large animals (spider crabs and ophiuroids) altered the biochemistry of labile OM, leading...H on marine animals is poorly understood (Fabry et al., 2008). Recent experiments suggest that it can lead to mortality in nematodes and harpacticoid copepods (Thistle et al., 2005; Fleeger et al., 2006). The scarcity in OMZ cores of organisms...

  10. Assessment of Streamside Management Zones for Conserving Benthic Macroinvertebrate Communities Following Timber Harvest in Eastern Kentucky Headwater Catchments

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    Joshua K. Adkins

    2016-06-01

    Full Text Available Headwater streams generally comprise the majority of stream area in a watershed and can have a strong influence on downstream food webs. Our objective was to determine the effect of altering streamside management zone (SMZ configurations on headwater aquatic insect communities. Timber harvests were implemented within six watersheds in eastern Kentucky. The SMZ configurations varied in width, canopy retention and best management practice (BMP utilization at the watershed scale. Benthic macroinvertebrate samples collected one year before and four years after harvest indicated few differences among treatments, although post-treatment abundance was elevated in some of the treatment streams relative to the unharvested controls. Jaccard index values were similar across SMZ treatments after logging, indicating strong community overlap. These findings suggest that stream invertebrate communities did respond to the timber harvest, though not negatively. Results also suggest that SMZ criteria for aquatic habitats in steeply sloping topography, including at least 50 percent canopy retention and widths of at least 16.8 m, appear to be adequate for protecting benthic macroinvertebrate communities from logging impacts.

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

    Science.gov (United States)

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

  12. Mapping benthic macroalgal communities in the coastal zone using CHRIS-PROBA mode 2 images

    Science.gov (United States)

    Casal, G.; Kutser, T.; Domínguez-Gómez, J. A.; Sánchez-Carnero, N.; Freire, J.

    2011-09-01

    The ecological importance of benthic macroalgal communities in coastal ecosystems has been recognised worldwide and the application of remote sensing to study these communities presents certain advantages respect to in situ methods. The present study used three CHRIS-PROBA images to analyse macroalgal communities distribution in the Seno de Corcubión (NW Spain). The use of this sensor represent a challenge given that its design, build and deployment programme is intended to follow the principles of the "faster, better, cheaper". To assess the application of this sensor to macroalgal mapping, two types of classifications were carried out: Maximum Likelihood and Spectral Angle Mapper (SAM). Maximum Likelihood classifier showed positive results, reaching overall accuracy percentages higher than 90% and kappa coefficients higher than 0.80 for the bottom classes shallow submerged sand, deep submerged sand, macroalgae less than 5 m and macroalgae between 5 and 10 m depth. The differentiation among macroalgal groups using SAM classifications showed positive results for green seaweeds although the differentiation between brown and red algae was not clear in the study area.

  13. Future Arctic Ocean Seasonal Ice Zones and Implications for Pelagic-Benthic Coupling

    OpenAIRE

    Paul Wassmann; Marit Reigstad

    2011-01-01

    Despite concerns about rapid changes in Arctic Ocean physical forcing and ecosystem function, quantitative knowledge and time series are scarce. The number of reliable physical-biological coupled models and models based on remote sensing is small. To improve our comprehension of carbon flux in the most prominent Arctic Ocean feature, the seasonal ice zone, a possible first step is to evaluate how biogeochemical cycling might develop in the future by examining conceptual models that address cl...

  14. Trophic structure of the benthic invertebrate community in the littoral zone of a mountain cascade system

    OpenAIRE

    Prus, M.; P. Bijok; Prus, T.

    2002-01-01

    The cascade of Solina/Myczkowce dam reservoirs situated in the West Carpathian Mts was investigated. The cascade consists of two reservoirs, the upper one built 35 yr ago on the San and Solinka Rivers of 2100 ha area separated from another one, of 190 ha area, with hypolimnion cold water supplied from the upper one.

    The offshore zone was investigated monthly (6 sites of upper, 3 sites of lower reservoir) using a tube bottom sampler. Besides numbers, biomass and biod...

  15. Trophic structure of the benthic invertebrate community in the littoral zone of a mountain cascade system

    Directory of Open Access Journals (Sweden)

    M. Prus

    2002-02-01

    Full Text Available The cascade of Solina/Myczkowce dam reservoirs situated in the West Carpathian Mts was investigated. The cascade consists of two reservoirs, the upper one built 35 yr ago on the San and Solinka Rivers of 2100 ha area separated from another one, of 190 ha area, with hypolimnion cold water supplied from the upper one.

    The offshore zone was investigated monthly (6 sites of upper, 3 sites of lower reservoir using a tube bottom sampler. Besides numbers, biomass and biodiversity indices, the proportion of predators, plant/detritus-feeders and filter-feeders was assessed.

    In upper reservoir Solina, with a lack of filter-feeders, a clear preponderance of plant-detritus feeders was observed. Predators, consisting mostly of leeches and hydranchnellids were present. In lower reservoir Myczkowce, all three trophic classes were present in the first year of study in almost equal proportions and in 1998 with slight preponderance of plant/detritus feeders was observed.

    The Oligochaeta/Chironomidae index in both reservoirs was low, indicating low degree of eutrophication. Only one site in Solina reservoir (near a fish culture and one in Myczkowce (influenced by tourist activity showed a high value of this index.

  16. Biofilm and Diatom Succession on Polyethylene (PE and Biodegradable Plastic Bags in Two Marine Habitats: Early Signs of Degradation in the Pelagic and Benthic Zone?

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    Andreas Eich

    Full Text Available The production of biodegradable plastic is increasing. Given the augmented littering of these products an increasing input into the sea is expected. Previous laboratory experiments have shown that degradation of plastic starts within days to weeks. Little is known about the early composition and activity of biofilms found on biodegradable and conventional plastic debris and its correlation to degradation in the marine environment. In this study we investigated the early formation of biofilms on plastic shopper bags and its consequences for the degradation of plastic. Samples of polyethylene and biodegradable plastic were tested in the Mediterranean Sea for 15 and 33 days. The samples were distributed equally to a shallow benthic (sedimentary seafloor at 6 m water depth and a pelagic habitat (3 m water depth to compare the impact of these different environments on fouling and degradation. The amount of biofilm increased on both plastic types and in both habitats. The diatom abundance and diversity differed significantly between the habitats and the plastic types. Diatoms were more abundant on samples from the pelagic zone. We anticipate that specific surface properties of the polymer types induced different biofilm communities on both plastic types. Additionally, different environmental conditions between the benthic and pelagic experimental site such as light intensity and shear forces may have influenced unequal colonisation between these habitats. The oxygen production rate was negative for all samples, indicating that the initial biofilm on marine plastic litter consumes oxygen, regardless of the plastic type or if exposed in the pelagic or the benthic zone. Mechanical tests did not reveal degradation within one month of exposure. However, scanning electron microscopy (SEM analysis displayed potential signs of degradation on the plastic surface, which differed between both plastic types. This study indicates that the early biofilm formation

  17. Biofilm and Diatom Succession on Polyethylene (PE) and Biodegradable Plastic Bags in Two Marine Habitats: Early Signs of Degradation in the Pelagic and Benthic Zone?

    Science.gov (United States)

    Eich, Andreas; Mildenberger, Tobias; Laforsch, Christian; Weber, Miriam

    2015-01-01

    The production of biodegradable plastic is increasing. Given the augmented littering of these products an increasing input into the sea is expected. Previous laboratory experiments have shown that degradation of plastic starts within days to weeks. Little is known about the early composition and activity of biofilms found on biodegradable and conventional plastic debris and its correlation to degradation in the marine environment. In this study we investigated the early formation of biofilms on plastic shopper bags and its consequences for the degradation of plastic. Samples of polyethylene and biodegradable plastic were tested in the Mediterranean Sea for 15 and 33 days. The samples were distributed equally to a shallow benthic (sedimentary seafloor at 6 m water depth) and a pelagic habitat (3 m water depth) to compare the impact of these different environments on fouling and degradation. The amount of biofilm increased on both plastic types and in both habitats. The diatom abundance and diversity differed significantly between the habitats and the plastic types. Diatoms were more abundant on samples from the pelagic zone. We anticipate that specific surface properties of the polymer types induced different biofilm communities on both plastic types. Additionally, different environmental conditions between the benthic and pelagic experimental site such as light intensity and shear forces may have influenced unequal colonisation between these habitats. The oxygen production rate was negative for all samples, indicating that the initial biofilm on marine plastic litter consumes oxygen, regardless of the plastic type or if exposed in the pelagic or the benthic zone. Mechanical tests did not reveal degradation within one month of exposure. However, scanning electron microscopy (SEM) analysis displayed potential signs of degradation on the plastic surface, which differed between both plastic types. This study indicates that the early biofilm formation and composition

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

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

    2016-04-01

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

  19. Bathymetric preference of four major genera of rectilinear benthic foraminifera within oxygen minimum zone in Arabian Sea off central west coast of India

    Science.gov (United States)

    Mazumder, Abhijit; Nigam, Rajiv

    2014-04-01

    Fifty two surface sediment samples collected from the region off Goa, central west coast of India from water depths of 15-3300 m were analyzed with special emphasis on foraminiferal content. Rectilinear benthic foraminiferal morphogroup shows a high relative abundance within Oxygen Minimum Zone (OMZ), both shallow marine (50-60 m water depth) and intermediate to deep water (150-1500 m water depth). We gave special emphasis on four rectilinear foraminiferal genera, namely Fursenkoina, Bolivina, Bulimina and Uvigerina to observe their individual distribution among OMZ. We found genus Fursenkoina predominates at the shallow water OMZ, within the water depth zone of 50-60 m. Within 150-1500 m water depth, which is considered as intermediate to deep water OMZ in this region, genus Uvigerina shows its highest abundance above 1000 m water depth, whereas genus Bulimina shows its affinity with deeper water environment (>1000 m water depth). Genus Bolivina does not show any such depth preference, except its higher abundance in only intermediate to deep water OMZ. This depth differentiation among four rectilinear benthic foraminiferal genera presents the basic data for palaeoclimatic study based on the extent and intensity of OMZ along with the palaeobathymetry study.

  20. Bathymetric preference of four major genera of rectilinear benthic foraminifera within oxygen minimum zone in Arabian Sea off central west coast of India

    Indian Academy of Sciences (India)

    Abhijit Mazumder; Rajiv Nigam

    2014-04-01

    Fifty two surface sediment samples collected from the region off Goa, central west coast of India from water depths of 15–3300 m were analyzed with special emphasis on foraminiferal content. Rectilinear benthic foraminiferal morphogroup shows a high relative abundance within Oxygen Minimum Zone (OMZ), both shallow marine (50–60 m water depth) and intermediate to deep water (150–1500 m water depth). We gave special emphasis on four rectilinear foraminiferal genera, namely Fursenkoina, Bolivina, Bulimina and Uvigerina to observe their individual distribution among OMZ. We found genus Fursenkoina predominates at the shallow water OMZ, within the water depth zone of 50–60 m. Within 150–1500 m water depth, which is considered as intermediate to deep water OMZ in this region, genus Uvigerina shows its highest abundance above 1000 m water depth, whereas genus Bulimina shows its affinity with deeper water environment (< 1000 m water depth). Genus Bolivina does not show any such depth preference, except its higher abundance in only intermediate to deep water OMZ. This depth differentiation among four rectilinear benthic foraminiferal genera presents the basic data for palaeoclimatic study based on the extent and intensity of OMZ along with the palaeobathymetry study.

  1. Sink or link? The bacterial role in benthic carbon cycling in the Arabian Sea's oxygen minimum zone

    OpenAIRE

    L Pozzato; van Oevelen, D.; Moodley, L.; Soetaert, K.; J. J. Middelburg

    2013-01-01

    The bacterial loop, the consumption of dissolved organic matter (DOM) by bacteria and subsequent transfer of bacterial carbon to higher trophic levels, plays a prominent role in pelagic food webs. However, its role in sedimentary ecosystems is not well documented. Here we present the results of isotope tracer experiments performed under in situ oxygen conditions in sediments from inside and outside the Arabian Sea’s oxygen minimum zone (OMZ) to study the importance of the microbial loop in th...

  2. Benthic Cover

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic cover (habitat) maps are derived from aerial imagery, underwater photos, acoustic surveys, and data gathered from sediment samples. Shallow to...

  3. Cold seep and oxygen minimum zone associated sources of margin heterogeneity affect benthic assemblages, diversity and nutrition at the Cascadian margin (NE Pacific Ocean)

    Science.gov (United States)

    Guilini, Katja; Levin, Lisa A.; Vanreusel, Ann

    2012-04-01

    Hydrate Ridge (HR), located on the northeastern Pacific margin off Oregon, is characterized by the presence of outcropping hydrates and active methane seepage. Additionally, permanent low oxygen conditions overlay the benthic realm. This study evaluated the relative influence of both seepage and oxygen minima as sources of habitat heterogeneity and potential stress-inducing features on the bathyal metazoan benthos (primarily nematodes) at three different seep and non-seep HR locations, exposed to decreasing bottom-water oxygen concentrations with increasing water depth. The nematode seep communities at HR exhibited low diversity with dominance of only one or two genera (Daptonema and Metadesmolaimus), elevated average individual biomass and δ13C evidence for strong dependance on chemosynthesis-derived carbon, resembling deep-sea seeps worldwide. Although the HR seep habitats harbored a distinct nematode community like in other known seep communities, they differed from deep-sea seeps in well-oxygenated waters based on that they shared the dominant genera with the surrounding non-seep sediments overlain by oxygen-deficient bottom water. The homogenizing effect of the oxygen minimum zone on the seep nematode assemblages and surrounding sediments was constant with increasing water depth and concomitant greater oxygen-deficiency, resulting in a loss of habitat heterogeneity.

  4. Sink or link? The bacterial role in benthic carbon cycling in the Arabian sea oxygen minimum zone

    Directory of Open Access Journals (Sweden)

    L. Pozzato

    2013-06-01

    Full Text Available The bacterial loop, the consumption of dissolved organic matter (DOM by bacteria and subsequent transfer of bacterial carbon to higher trophic levels, plays a prominent role in pelagic aquatic food webs. However, its role in sedimentary ecosystems is not well documented. Here we present the results of isotope tracer experiments performed under in situ oxygen conditions in sediments from inside and outside the Arabian Sea Oxygen Minimum Zone (OMZ to study the importance of the microbial loop in this setting. Particulate organic matter, added as phytodetritus, was processed by bacteria, protozoa and metazoans, while dissolved organic matter was processed only by bacteria and there was very little, if any, transfer to higher trophic levels within the experimental period. This lack of significant transfer of bacterial-derived carbon to metazoan consumers indicates that the bacterial loop is rather inefficient in these sediments. Moreover, metazoans directly consume labile particulate organic matter resources and thus compete with bacteria for phytodetritus.

  5. Benthic macrofauna

    Digital Repository Service at National Institute of Oceanography (India)

    Ansari, Z.A.; Sivadas, S.; Ingole, B.S.

    in these waters has been empirically defined as animals retained by 0.5mm screens. Many organ- isms can thus be seen only on close inspection, while other may weigh several grams while fresh. Benthic macrofauna are good indicators of estuarine conditions because... they are relatively sedentary at the sediment?water interface and within deeper sediments (Dauer and Conner 1980). The abundance of benthic animals in an area is closely related to its environment and reflects the characteristics of an ecological niche (Ansari et al...

  6. St. Croix, USVI Land-sea characterization of East End Marine Park to evaluate zones and support management plan review: 2011 benthic habitat assessment

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This fish and benthic composition database is the result of a multifaceted effort described below. The intent of this work is five fold: 1) To spatially...

  7. Evaluation of I/Ca ratios in benthic foraminifera from the Peruvian oxygen minimum zone as proxy for redox conditions in the ambient water masses

    Science.gov (United States)

    Glock, N.; Liebetrau, V.; Eisenhauer, A.

    2014-12-01

    Tropical oxygen minimum zones (OMZs) are most important areas of oxygen depletion in today´s oceans and nutrient cycling in these regions has a large socio-economic impact because they account for about 17% of the global commercial fish catches(1). Possibly increasing magnitude and area of oxygen depletion in these regions, might endanger rich pelagic fish habitats in the future threatening the global marine food supply. By the use of a quantitative redox proxy in OMZs, reconstruction of the temporal variation in OMZ extension eventually providing information about past and future changes in oxygenation and the anthropogenic role in the recent trend of expanding OMZs(2). Recent work has shown that iodine/calcium (I/Ca) ratios in marine carbonates are a promising proxy for ambient oxygen concentration(3). Our study explores the correlation of I/Ca ratios in four benthic foraminiferal species (three calcitic, one aragonitic) from the Peruvian OMZ to bottom water oxygen concentrations ([O2]BW) and evaluates foraminiferal I/Ca ratios as a possible redox proxy for the ambient water masses. Our results show that all species have a positive trend in the I/Ca ratios as a function of [O2]BW. Only for the aragonitic species Hoeglundina elegans this trend is not significant. The highest significance has been found for Uvigerina striata (I/Ca = 0.032(±0.004).[O2]BW + 0.29(±0.03), R² = 0.61, F = 75, P issues which have to be considered. These "pitfalls" include: (i) the volatility of iodine in acidic solutions, (ii) a species dependency of the I/Ca-[O2]BW relationship which is either related to a strong vital effect or toa species dependency on the calcification depth within sediment, and (iii) the inter-test variability of I/Ca between different specimens from the same species and habitat. (1): FAO FishStat: Fisheries and aquaculture software. In: FAO Fisheries and Aquaculture Department[online]. Rome. Updated 28 Nov. 2013. (2): Stramma et al.: Expanding Oxygen

  8. Benthic foraminifera

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.; Nigam, R.

    Paula, Goa, India (For Correspondence: rsaraswat@nio.org) (Modified after Paul Loubre# and William Austin$) # Department of Geology and Environmental Geosciences, Davis Hall, Northern Illinois University, DeKalb, Illinois 60115 USA $ School... and trochospiral forms) (Figure 1). The external surface of the shell is often ornamented with pits, ribs, spines, plates, etc. The benthic foraminifers communicate with the surrounding environment through an opening in the shell, called as aperture. A web...

  9. An End-to-End DNA Taxonomy Methodology for Benthic Biodiversity Survey in the Clarion-Clipperton Zone, Central Pacific Abyss

    Directory of Open Access Journals (Sweden)

    Adrian G. Glover

    2015-12-01

    Full Text Available Recent years have seen increased survey and sampling expeditions to the Clarion-Clipperton Zone (CCZ, central Pacific Ocean abyss, driven by commercial interests from contractors in the potential extraction of polymetallic nodules in the region. Part of the International Seabed Authority (ISA regulatory requirements are that these contractors undertake environmental research expeditions to their CCZ exploration claims following guidelines approved by the ISA Legal and Technical Commission (ISA, 2010. Section 9 (e of these guidelines instructs contractors to “…collect data on the sea floor communities specifically relating to megafauna, macrofauna, meiofauna, microfauna, nodule fauna and demersal scavengers”. There are a number of methodological challenges to this, including the water depth (4000–5000 m, extremely warm surface waters (~28 °C compared to bottom water (~1.5 °C and great distances to ports requiring a large and long seagoing expedition with only a limited number of scientists. Both scientists and regulators have recently realized that a major gap in our knowledge of the region is the fundamental taxonomy of the animals that live there; this is essential to inform our knowledge of the biogeography, natural history and ultimately our stewardship of the region. Recognising this, the ISA is currently sponsoring a series of taxonomic workshops on the CCZ fauna and to assist in this process we present here a series of methodological pipelines for DNA taxonomy (incorporating both molecular and morphological data of the macrofauna and megafauna from the CCZ benthic habitat in the recent ABYSSLINE cruise program to the UK-1 exploration claim. A major problem on recent CCZ cruises has been the collection of high-quality samples suitable for both morphology and DNA taxonomy, coupled with a workflow that ensures these data are made available. The DNA sequencing techniques themselves are relatively standard, once good samples have been

  10. Cold seep and oxygen minimum zone associated sources of margin heterogeneity affect benthic assemblages, diversity and nutrition at the Cascadian margin (NE Pacific Ocean)

    OpenAIRE

    Guilini, K.; Levin, L. A.; Vanreusel, A.

    2012-01-01

    Hydrate Ridge (HR), located on the northeastern Pacific margin off Oregon, is characterized by the presence of outcropping hydrates and active methane seepage. Additionally, permanent low oxygen conditions overlay the benthic realm. This study evaluated the relative influence of both seepage and oxygen minima as sources of habitat heterogeneity and potential stress-inducing features on the bathyal metazoan benthos (primarily nematodes) at three different seep and non-seep HR locations, expose...

  11. Secondary productivity of benthic macrofaunal community in intertidal zone of Lianzhou Bay, China%廉州湾滨海湿地潮间带大型底栖动物群落次级生产力

    Institute of Scientific and Technical Information of China (English)

    何斌源; 赖廷和; 王欣; 潘良浩; 曹庆先

    2013-01-01

    A seasonal investigation was conducted on the dynamic changes of benthic macrofaunal community in the three types of intertidal habitats,i.e.,bare flat,mangrove forest,and Cyperus malaccensis saltmarsh,in Lianzhou Bay in January,April,July,and October,2011,and the Brey's empirical formula was applied to estimate the secondary productivity of benthic macrofaunal community in the three habitats.A total 156 species belonging to 8 phyla of intertidal benthic macrofauna were collected,among which,136,85,and 29 species were recorded in bare flat,mangrove forest,and saltmarsh habitats,respectively.The average species abundance per sampling station was 9.5±4.8 species in bare flat,9.5±3.9 species in mangrove forest,and 5.9±1.9 species in saltmarsh,respectively.In all the three habitats,the percentages of different categories to total species followed the same decreasing order of Mollusk > Arthropod > Annelid >Chordate > other categories.The community structure of the benthic macrofauna in saltmarsh had smaller change,with Ilyoplax ningpoensis significantly dominated.In mangrove forest and bare flat,the dominant species changed with the water salinity.In the intertidal zone of Lianzhou Bay,the average secondary productivity of the benthic macrofaunal community was 15.88 g· m-2· a-1,and that in bare flat,mangrove forest,and saltmarsh was 16.16 g · m-2· a-1,9.97 g · m-2 · a-1,and 3.88 g · m-2 · a-1,respectively.The average P/B ratio in the intertidal zone was 0.70,and that in bare flat,mangrove forest,and saltmarsh was 0.70,0.65,and 1.02,respectively.The annual secondary production in the intertidal zone was 14623 t (FM).Water salinity and vegetation type were the major factors affecting the community structure of the intertidal benthic macrofauna,and further,the spatial distribution of the secondary productivity of the benthic macrofauna in Lianzhou Bay.%于2011年1月、4月、7月和10月开展广西廉州湾的

  12. Benthic Habitat and Zone Maps of St. Croix, U.S. Virgin Islands 1999 - Prepared by Visual Interpretation from Remote Sensing Imagery Collected by NOAA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — There are 30 habitat and zone PDF products. This project is a cooperative effort between the National Ocean Service, National Centers for Coastal Ocean Science,...

  13. Benthic Habitat and Zone Maps of St. Thomas and St. John, U.S. Virgin Islands - Prepared by Visual Interpretation from Remote Sensing Imagery Collected by NOAA, 1999

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Ther are 25 habitat and zone PDF products. This project is a cooperative effort between the National Ocean Service, National Centers for Coastal Ocean Science,...

  14. Benthic Habitat and Zone Maps of Puerto Rico 1999 - Prepared by Visual Interpretation from Remote Sensing Imagery Collected by NOAA, 1999

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — There are 208 habitat and zone maps of Puerto Rico and is major islands. This project is a cooperative effort between the National Ocean Service, National Centers...

  15. Temporal changes of environmental impact in the coastal marine area in front of a former mining zone, detected by means of benthic foraminifera

    Science.gov (United States)

    Romano, Elena; Bergamin, Luisa; Maggi, Chiara; Ausili, Antonella

    2016-04-01

    Benthic foraminifera are increasingly used to assess environmental quality of present and past marine environments. They are suitable for the study of ancient environments because their hard and small shells are preserved and abundant in sediment and an adequate number of them can be collected by small samples of sediment cores, supplying reliable data for a statistical approach. The study of foraminiferal assemblages, associated to sediment abiotic parameters, allows to define the anthropogenic impact along the time; reference conditions may be recognized in deep uncontaminated levels. The Sulcis Iglesiente Guspinese area (SW Sardinia, Italy) was affected in past times by intensive mining, which started in mid 19th century and ceased in 1990s. The marine area of Cala Domestica is located few kilometers from the mining district, where mainly galena and sphalerite were exploited. The area houses buildings for storage of minerals receives drainage material from mineral dumps determining a strong enrichment for several metals in the coastal sediments. Sediment core SI/69 was collected by means of vibrocorer in front of Cala Domestica beach, during a vast sampling survey aimed to environmental characterization of marine sediments. The core was subsampled in the laboratory, and a total of 28 levels were collected. Microfaunal, grain size and chemical (As, Ba, Cd, Cr, Cu, Fe, Hg, Mn, Ni, Pb, Zn) analyses were carried out on different aliquots of the same level. The quantitative analysis on benthic foraminifera was based on the count of at least 300 specimens per sample. Faunal parameters such as Foraminiferal Number (FN i.e. number of specimens / 1 g dry sediment) and species diversity (- index and H-index) were considered as potential indicators of environmental status. Principal Component Analysis (PCA) showed a group of strongly correlated metals (Ba, Cd, Cu, Hg, Mn, Pb and Zn), associated to the superficial samples. These elements displayed a typical profile along

  16. Bathymetric preference of four major genera of rectilinear benthic foraminifera within oxygen minimum zone in Arabian Sea off central west coast of India.

    Digital Repository Service at National Institute of Oceanography (India)

    Mazumder, A.; Nigam, R.

    - enclosure morphology of the northern Arabian Sea (Wyrtki 1973; Shetye et al. 1994) are the main factors responsible for this low oxygen concentra- tion. Apart from this OMZ, a shallow water oxygen depleted zone (∼50–60 m) has been reported from different...- thic foraminifera groups, viz., the species under the genus Bolivina, in oxygen-depleted environments have been reported (Phleger and Soutar 1973; Mackensen and Douglas 1989; Bernhard 1993; Sen Gupta and Machain-Castillo 1993; Alve 1994, 1995; Bernhard...

  17. Effects of Forested Streamside Management Zone Widths and Thinning on Carbon Dynamics and Benthic Macroinvertebrates for Pine Plantations in the Piedmont of Virginia

    OpenAIRE

    Wadl, Erica Fritz

    2008-01-01

    To protect the integrity of the United Stateâ s waters, the Federal Water Pollution Control Act of 1972 promoted the establishment of Best Management Practices (BMPs) for forestry. A commonly used BMP is the reservation of Streamside Management Zones (SMZs). In this study the effectiveness of three different SMZ widths, 30.5 m (100 ft), 15.3 m (50 ft), and 7.6 m (25 ft), as well as thinning in 15.3 m SMZs were studied. The objectives of the study were to determine the effects these SMZ tr...

  18. St. Croix, USVI Land-sea characterization of East End Marine Park to evaluate zones and support management plan review: 2011 benthic habitat assessment (NODC Accession 0125270 and 0125236)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This fish and benthic composition database is the result of a multifaceted effort described below. The intent of this work is five fold: 1) To spatially...

  19. NEPR Geographic Zone Map 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This geographic zone map was created by interpreting satellite and aerial imagery, seafloor topography (bathymetry model), and the new NEPR Benthic Habitat Map...

  20. Benthic oxygen exchange in a live coralline algal bed and an adjacent sandy habitat

    DEFF Research Database (Denmark)

    Attard, Karl M.; Stahl, Henrik; Kamenos, Nicholas A.; Turner, Gavin; Burdett, Heidi L.; Glud, Ronnie N.

    2015-01-01

    community benthic gross primary productivity (GPP), respiration (R), and net ecosystem metabolism (NEM) derived from diel EC time series collected during 5 seasonal measurement campaigns in temperate Loch Sween, Scotland. Measurements were also carried out at an adjacent (similar to 20 m distant) permeable......(-1) of carbon at the maerl bed and sand site, respectively, were required to sustain the benthic O-2 demand. Thus, the 2 benthic habitats efficiently entrap organic carbon and are sinks of organic material in the coastal zone. Parallel deployment of 0.1 m(2) benthic chambers during nighttime revealed...

  1. Biodiversity in Benthic Ecology

    DEFF Research Database (Denmark)

    Friberg, Nikolai; Carl, J. D.

    Foreword: This proceeding is based on a set of papers presented at the second Nordic Benthological Meeting held in Silkeborg, November 13-14, 1997. The main theme of the meeting was biodiversity in benthic ecology and the majority of contributions touch on this subject. In addition, the proceeding...

  2. Benthic fauna around Mauritius island, southwest Indian Ocean

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Ansari, Z.A.; Parulekar, A.H.

    Distribution of benthic fauna in the Exclusive Economic Zone of Mauritius was studied during September-October 1987. Mean faunal density (macro+meio) and dry weight biomass was 10848 no.m/2 and 228.8 mg.m/2, respectively. The macrofauna was dominat...

  3. Benthic diatoms in lakes

    OpenAIRE

    Gottschalk, Steffi

    2014-01-01

    In order to protect or improve surface waters ecosystem response to pressures needs to be quantified. Diatoms are frequently used for assessing ecological status in streams and for reconstructing water quality of lakes. However, ecological status assessment of European lakes based on extant diatom assemblages is rare. The overall aim of this thesis is to facilitate the application of benthic diatoms in water quality assessment of boreal lakes, using methods developed for stream assessmen...

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

    Science.gov (United States)

    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...

  5. National Benthic Infaunal Database (NBID)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NBID is a quantitative database on abundances of individual benthic species by sample and study region, along with other synoptically measured environmental...

  6. NEPR Benthic Habitat Map 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This benthic habitat map was created from a semi-automated habitat mapping process, using a combination of bathymetry, satellite imagery, aerial imagery and...

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

    Science.gov (United States)

    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

  8. Northeast Puerto Rico and Culebra Island - Geographic Zone Map 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This geographic zone map was created by interpreting satellite and aerial imagery, seafloor topography (bathymetry model), and the new NEPR Benthic Habitat Map...

  9. Bathymetric Position Index (BPI) Zones derived from gridded bathymetry of Swains Island,Territory of American Samoa, USA

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — BPI Zones are derived from gridded (40 m cell size) multibeam bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai. BPI Zones was created using the Benthic...

  10. Effects of beam and pulse trawling on the benthic ecosystem

    OpenAIRE

    Teal, L.R.; Depestele, J.; O'Neill, B; Craeymeersch, J.A.M.; Denderen, van, A.C.; Parker, R.; Perdon, K.J.; H. POLET; Rasenberg, M.M.M.; Vanelslander, B.; Rijnsdorp, A.D.

    2014-01-01

    Here we study the effects of fishing trawl gear on the seabed and benthic organisms. A BACI-design experiment was used to examine the effects of a traditional beam trawl gear and the pulse trawl gear. The pulse trawl gear is gaining popularity amongst Dutch fishers in recent years due to reduced fuel costs and good sole catches.The research was carried out in the northern part of the Dutch Voordelta (southern North Sea coastal zone area, 15 – 22m deep, sandy habitat) in June 2013. In this exp...

  11. Profundal benthic invertebrates in an oligotrophic tropical lake: different strategies for coping with anoxia

    Directory of Open Access Journals (Sweden)

    María del Carmen Hernández

    2014-05-01

    Full Text Available The deep benthic communities of tropical lakes are poorly understood with respect to their composition, abundance, biomass and regulatory factors. Whereas the hypolimnia of temperate oligotrophic lakes remain oxygenated, the higher temperatures in tropical lakes frequently lead to the rapid development of hypolimnetic anoxia independent of trophic status. The deep benthic communities of tropical lakes must therefore develop strategies to respond to anoxic conditions. The dynamics of the deep benthic community of Lake Alchichica were studied over 15 months. We hypothesized that the sedimentation of the winter diatom bloom constitutes an input of high-quality food that contributes to the establishment and development of the deep benthic community. However, the remineralization of this organic matter leads to the prompt development of hypolimnetic anoxia, thus limiting the establishment and/or persistence of the deep benthic community. In contrast with the diverse littoral benthic community (50 taxa in Lake Alchichica, only two species constitute its deep benthic community, the ostracod Candona cf. patzcuaro and the chironomid Chironomus cf. austini, which combined exhibit a low density (1197±1976 ind m-2 and biomass (16.13±30.81 mg C m-2. C. patzcuaro is dominant and is present throughout the year, whereas Ch. austini is recorded only when the bottom water of the lake is oxygenated. A comparison with the analogous but temperate Lake Mergozzo in Italy illustrates the role that anoxia plays in tropical lakes by diminishing not only taxonomic richness (13 versus 2 spp. in temperate versus tropical lakes, respectively but also abundance (1145 versus 287 ind m-2, respectively. C. patzcuaro is found throughout the annual cycle of the lake’s profundal zone, entering into diapause during the anoxic period and recovering as soon as the profundal zone reoxygenates. Ch. austini has adjusted its life cycle to use the habitat and available resources while

  12. Spatial heterogeneity of benthic community assemblages with an emphasis on reef algae at French Frigate Shoals, Northwestern Hawai`ian Islands

    Science.gov (United States)

    Vroom, Peter S.; Page, Kimberly N.; Peyton, Kimberly A.; Kukea-Shultz, J. Kanekoa

    2005-12-01

    Reefs in tropical atoll systems have historically been described on a geomorphic basis, and segregated into loosely defined fore-reef, back-reef, and lagoonal reef zones. However, recent oceanographic monitoring data have shown that physical factors within a single geomorphic zone can vary significantly, calling into question whether benthic communities within a single zone are biologically similar. To determine the amount of benthic variability that may occur in a geomorphic zone, percent cover of benthic organisms was determined at the species level for 28 sites in three geomorphic zones at French Frigate Shoals, Northwestern Hawai‘ian Islands. Multivariate statistical analyses found most windward fore-reef and back-reef sites to be statistically similar, but considerable variation to exist among sites within calmer lagoonal areas. Surveys revealed macroalgae to dominate over scleractinian coral species at the majority of sites in this healthy, subtropical reef system, although select lagoonal areas were dominated by dense coral communities.

  13. Mechanisms of temporary adhesion in benthic animals

    NARCIS (Netherlands)

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

    2011-01-01

    Adhesive systems are ubiquitous in benthic animals and play a key role in diverse functions such as locomotion, food capture, mating, burrow building, and defence. For benthic animals that release adhesives, surface and material properties and external morphology have received little attention compa

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

    Science.gov (United States)

    Dinçer, Feyza

    2016-02-01

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

  15. Bathymetric Bathymetric Position Index (BPI) Zones 20 m grid derived from gridded bathymetry of Baker Island, Pacific Remote Island Areas, Central Pacific.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — BPI Zones are derived from gridded (20 m cell size) multibeam bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai. BPI Zones was created using the Benthic...

  16. Bathymetric Bathymetric Position Index (BPI) Zones 40 m grid derived from gridded bathymetry of Howland Island, Pacific Remote Island Areas, Central Pacific.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — BPI Zones are derived from gridded (40 m cell size) multibeam bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai. BPI Zones was created using the Benthic...

  17. Bathymetric Bathymetric Position Index (BPI) Zones 20 m grid derived from gridded bathymetry of Johnston Island, Pacific Remote Island Areas, Central Pacific.

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — BPI Zones are derived from gridded (20 m cell size) multibeam bathymetry, collected aboard R/V AHI and NOAA ship Hi'ialakai. BPI Zones was created using the Benthic...

  18. Field experiments on responses of a freshwater, benthic macroinvertebrate community to vertebrate predators

    International Nuclear Information System (INIS)

    The seasonal importance of vertebrate predators in potentially regulating the abundance and diversity of the benthic macroinvertebrates in the littoral zone of a soft-bottom reservoir that receives thermal effluent from a nuclear production reactor was examined. Thirty-six predator (fish and turtle) exclusion cages (4 m2) were placed in shallow water at six locations along a thermal gradient in Par Pond, a 1100-ha cooling reservoir on the Savannah River Plant near Aiken, South Carolina, USA. An additional 36 control plots (4 m2) were also set up. Cages were in place during three, 3-mo test periods beginning in September 1977. Estimates of benthic density, taxon richness, and distribution within functional groups (defined by feeding mechanism) were calculated for each test period. Effects of temperature on predator-prey relationships were also determined. Experimental results of this study suggest that vertebrate predation was not the fundamental parameter organizing the benthic macroinvertebrate community in the littoral zone of this reservoir. Neither taxon richness nor density of total macroinvertebrates was conclusively related to predator treatment. Relationships between predator treatment and community response (changes in density and taxon richness) were generally unaffected by either plot locality, temperature fluctuations from thermal effluent, or seasonal changes. When data from caged and control plots were pooled, however, both location and water temperature individually had direct impacts on the benthic community. From these results and other field studies it is hypothesized that individual species of keystone benthic predators do not occur in the littoral zone of freshwater lentic environments with soft bottoms

  19. Benthic Habitats of the Florida Keys

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The benthic habitats of the Florida Keys were mapped from a series of 450 aerial photographs. Ecologists outlined the boundaries of specific habitat types by...

  20. BENTHIC MACROFAUNAL ALIENS IN WILLAPA BAY

    Science.gov (United States)

    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...

  1. Feasibility of remote sensing benthic microalgae

    Science.gov (United States)

    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.

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

    Science.gov (United States)

    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 Ostrovački 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 Ostrovački section. In the central part of section, wavy to smooth thin (< 1 mm) crusts (laminas) alternating with encrusted corals occur. The

  3. A biodiversidade bentônica em lagoa marginal ao rio Paranapanema na zona de sua desembocadura, na represa de Jurumirim - DOI: 10.4025/actascibiolsci.v28i4.166 The benthic biodiversity in a lake marginal to the Paranapanema river in its mouth zone into Jurumirim reservoir- DOI: 10.4025/actascibiolsci.166

    Directory of Open Access Journals (Sweden)

    Rosemary Cristina Souza Davanso

    2007-11-01

    Full Text Available O presente trabalho teve como objetivo principal verificar a biodiversidade bentônica em áreas do fundo da lagoa do Coqueiral, zona de desembocadura do rio Paranapanema, na represa de Jurumirim, Estado de São Paulo. Foram selecionados dezoito pontos de amostragem, englobando áreas rasas e áreas profundas. As coletas foram feitas em intervalos trimestrais ao longo de um ano; também foram analisadas as variáveis físicas e químicas da água (nível, transparência, temperatura, oxigênio dissolvido, pH e condutividade elétrica. Amostras do sedimento, para análise da fauna e de fatores abióticos (granulometria e conteúdo orgânico, foram recolhidas em tréplicas, utilizando como coletor a draga de Petersen. O material foi triado e analisado sob microscópio estereoscópico. Contagem e identificação dos organismos foram realizadas, e densidade, abundância relativa, riqueza taxonômica e índice de dominância foram calculados. A análise revelou uma fauna com baixa diversidade e a dominância de Chironomidae e Ephemeroptera. Domínio de Ephemeroptera, constituído por Campsurus, ocorreu no período mais quente do ano e com baixa profundidade da lagoa. A distribuição dos organismos teve como principais fatores determinantes profundidade, transparência, pH e temperatura da água. Na comparação feita entre áreas rasas e profundas, foi observada uma menor densidade de organismos nas regiões profundas.Coqueiral lake is a marginal lake located at the southeast São Paulo State, in the mouth zone of the Paranapanema river into Jurumirim Reservoir and it has high connectivity with the Paranapanema river. This work aimed to verify the benthic biodiversity in areas of the lake bottom. 18 sampling sites in the lake were selected, including shallow and deep areas. The samples were taken every three months during one year. Physical and chemical water variables (level, transparency, dissolved oxygen, pH, and electric conductivity were

  4. Divergent ecosystem responses within a benthic marine community to ocean acidification

    OpenAIRE

    Kroeker, Kristy J.; Micheli, Fiorenza; Gambi, Maria Cristina; Martz, Todd R.

    2011-01-01

    Ocean acidification is predicted to impact all areas of the oceans and affect a diversity of marine organisms. However, the diversity of responses among species prevents clear predictions about the impact of acidification at the ecosystem level. Here, we used shallow water CO2 vents in the Mediterranean Sea as a model system to examine emergent ecosystem responses to ocean acidification in rocky reef communities. We assessed in situ benthic invertebrate communities in three distinct pH zones ...

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

    Science.gov (United States)

    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 ...

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

    Science.gov (United States)

    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.

  7. History of benthic research in the English Channel: From general patterns of communities to habitat mosaic description

    Science.gov (United States)

    Dauvin, Jean-Claude

    2015-06-01

    combined to allow the description of benthic habitats using numerous descriptors. These approaches were mainly applied on a local scale, leading to the identification of habitat mosaics mainly in coarse sands, gravels and pebbly areas which cover 80% of the EC seabed. They also allowed the enrichment of the EUNIS habitat classification for infralittoral and circalittoral zones taking into account the scale of observations of benthic habitats. Moreover, several recommendations for future benthic studies are proposed within a HABITAT approach.

  8. A simple method to correct the results of acoustic surveys for fish hidden in the dead zone

    Czech Academy of Sciences Publication Activity Database

    Tušer, Michal; Prchalová, Marie; Mrkvička, Tomáš; Frouzová, Jaroslava; Čech, Martin; Peterka, Jiří; Jůza, Tomáš; Vašek, Mojmír; Kratochvíl, Michal; Draštík, Vladislav; Kubečka, Jan

    2013-01-01

    Roč. 29, č. 2 (2013), s. 358-363. ISSN 0175-8659 R&D Projects: GA MZe(CZ) QH81046 Institutional support: RVO:60077344 Keywords : acoustic dead zone * benthic gillnet * freshwater benthic habitats * bottom slope Subject RIV: EH - Ecology, Behaviour Impact factor: 0.903, year: 2013

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

    Science.gov (United States)

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

    2016-01-01

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

  10. Recruitment of benthic animals as a function of petroleum hydrocarbon concentrations in the sediment

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, J. W.; Riley, R. G.; Bean, R. M.

    1977-01-01

    Three separate field installations, consisting of clean and oiled sediment in fiberglass trays, were placed in the intertidal zone of Sequim Bay, Washington to determine rates of hydrocarbon depuration and recruitment of benthic organisms. Detailed chemical analysis, using glass capillary gas chromatography, and GC/MS, were conducted such that individual components and hydrocarbon classes associated with the sediment after varying periods of field depuration could be quantitated. Depuration rates of hydrocarbon types in sediment receiving oil on the surface decreased in the order of saturates, methylnaphthalenes and methylphenanthrenes. The time to 50% depuration (half-time) for these coarse sediments was approximately 100 days, while sediment mixed with oil had only decreased by about 20 to 30% by 100 days. Levels of the aromatics (naphthalenes and phenanthrenes) in the two systems followed the general pattern, but very little loss was exhibited when oil was mixed with sediment. No substantial inhibition of benthic organism recruitment was produced by either type of sediment contamination. There was a tendency for suppression of populations of mature and juvenile bivalves (Mysella tumida) at the last sampling interval for all three installations. Future sampling of these populations and further analyses of all benthic organisms may provide a better evaluation of effects of specific hydrocarbon components in sediments on benthic recruitment. These results are discussed in light of oil spill studies and other field experiments.

  11. Data-Driven Approach to Benthic Cover Type Classification Using Bathymetric LiDAR Waveform Analysis

    Directory of Open Access Journals (Sweden)

    Teemu Kumpumäki

    2015-10-01

    Full Text Available A data-driven method for describing the benthic cover type based on full-waveform bathymetric LiDAR data analysis is presented. The waveform of the bathymetric LiDAR return pulse is first modeled as a sum of three functions: a Gaussian pulse representing the surface return, a function modeling the backscatter and another Gaussian pulse modeling the return from the bottom surface. Two sets of variables are formed: one containing features describing the bottom return and the other describing various conditions, such as water quality and the depth of the seabed. Regression analysis is used to eliminate the effect of the condition variables on the features, after which the features are mapped onto a cell lattice using a self-organizing map (SOM. The cells of the SOM are grouped into seven clusters using the neighborhood distance matrix method. The clustering result is evaluated using the seabed substrate map based on sonar measurements, as well as delineation of photic zones in the study area. High correspondence between the clusters and the substrate type/photic zone has been obtained indicating that the proposed clustering method adequately describes the benthic cover in the study area. The bottom return pulse waveforms corresponding to the clusters and a cluster map of the study area are also presented. The method can be used for clustering full waveform bathymetric LiDAR data acquired from large areas to discover the structure of benthic cover types and to focus the field studies accordingly.

  12. Microphytobenthos in ecotoxicology: a review of the use of marine benthic diatoms in bioassays.

    Science.gov (United States)

    Araújo, Cristiano V M; Blasco, Julián; Moreno-Garrido, Ignacio

    2010-08-01

    Contamination in coastal zones is an increasing problem that adversely affects biological diversity and the functioning of coastal ecosystems. Sediment is an important compartment of these zones since large quantities of diverse contaminants can accumulate there. Whole-sediment toxicity assays are of increasing importance, and several assay methods using mainly invertebrates have been developed. However, an important part of the benthic community, the microphytobenthos (represented principally by benthic diatoms and cyanobacteria), has surprisingly been neglected. Recently, comprehensive studies have been conducted using benthic marine microalgae with the object of establishing a toxicity assay method for sediment samples. The main results published to date in the literature and obtained by our own team have been compiled and are discussed in this review. The value and feasibility of using certain organisms of the microphytobenthos group in ecotoxicology studies are also discussed, and a sediment quality guideline based on multivariate procedure has been derived from data obtained in previous studies. Finally, future perspectives for research in this field are discussed. PMID:20493528

  13. Sensitivity of Coastal Environments and Wildlife to Spilled Oil: South Florida: BENTHIC (Benthic Polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains benthic habitats, including coral reef and hardbottom, seagrass, algae, and others in [for] South Florida. Vector polygons in the data set...

  14. Benthic community structure and organic matter variation in response to oceanographic events on the Brazilian SE inner shelf

    Science.gov (United States)

    Rodrigues Alves, Betina G.; Ziggiatti Güth, Arthur; Caruso Bícego, Márcia; Airton Gaeta, Salvador; Gomes Sumida, Paulo Yukio

    2014-08-01

    For 13 months, this study monitored the sedimentary organic matter composition, benthic bacteria and macrofauna at a permanent sampling station on the inner shelf (~ 40 m depth) near Ubatuba in SE Brazil. The sedimentary organic matter compounds were evaluated for total organic matter content, lipid biomarkers and phytopigments. The organic matter content varied significantly over time but no clear seasonal trend was evident. Lipid biomarker composition revealed that particulate organic matter was primarily derived from autochthonous sources, such as diatoms, other microalgae, zooplankton, sediment bacteria and benthic metazoan fauna. Phytopigment results revealed that the majority of the organic matter in the sediments was refractory as opposed to labile, suggesting that the labile portion is rapidly consumed. The benthic dynamics off the coast of Ubatuba is highly influenced by the intrusion of the South Atlantic Central Water (SACW) onto the shelf, which brings nutrients up to the euphotic zone and stimulates new phytoplanktonic production. This enhances the flux of organic matter to the bottom and increases benthic biota density, mainly bacteria. These results suggest a strong and complex benthic-pelagic coupling that is influenced by both mesoscale oceanographic events (i.e., intrusion of SACW) and local events (cold fronts) through remobilization of the sediments.

  15. Allelopathy in benthic and littoral areas : case studies on allelochemicals from benthic cyanobacteria and submersed macrophytes

    OpenAIRE

    Gross, Elisabeth

    1999-01-01

    Photosynthetic organisms in littoral and benthic habitats are in general situated in close proximity to their competitors. Benthic algae and cyanobacteria compete for space and grow adjacent to each other. Submersed macrophytes can be overgrown by epiphytic algae and are surrounded by other macrophytes and phytoplankton. The particular spatial setup in these habitats makes allelopathy a powerful strategy. Released compounds can more or less directly reach and act on target organisms. Allelopa...

  16. Effects of fluctuating hypoxia on benthic oxygen consumption in the Black Sea (Crimean Shelf

    Directory of Open Access Journals (Sweden)

    A. Lichtschlag

    2015-04-01

    Full Text Available The outer Western Crimean Shelf of the Black Sea is a natural laboratory to investigate effects of stable oxic vs. varying hypoxic conditions on seafloor biogeochemical processes and benthic community structure. Bottom water oxygen concentrations varied between normoxic (175 μmol O2 L−1 and hypoxic (2 L−1 or even anoxic/sulfidic conditions within a few kilometres distance. Variations in oxygen concentrations between 160 and 10 μmol L−1 even occurred within hours close to the chemocline at 134 m water depth. Total oxygen uptake, including diffusive as well as fauna-mediated oxygen consumption, decreased from > 15 mmol m−2 d−1 in the oxic zone to −2 d−1 in the hypoxic zone, correlating with changes in macrobenthos composition. Benthic diffusive oxygen uptake rates, comprising microbial respiration plus reoxidation of inorganic products, were around 4.5 mmol m−2 d−1, but declined to 1.3 mmol m−2 d−1 at oxygen concentrations below 20 μmol L−1. Measurements and modelling of pore water profiles indicated that reoxidation of reduced compounds played only a minor role in the diffusive oxygen uptake, leaving the major fraction to aerobic degradation of organic carbon. Remineralization efficiency decreased from 100% in the oxic zone, to 50% in the oxic-hypoxic, to 10% in the hypoxic-anoxic zone. Overall the faunal remineralization rate was more important, but also more influenced by fluctuating oxygen concentrations than microbial and geochemical oxidation processes.

  17. Predicting estuarine benthic production using functional diversity

    Directory of Open Access Journals (Sweden)

    Marina Dolbeth

    2014-05-01

    Full Text Available We considered an estuarine system having naturally low levels of diversity, but attaining considerable high production levels, and being subjected to different sorts of anthropogenic impacts and climate events to investigate the relationship between diversity and secondary production. Functional diversity measures were used to predict benthic production, which is considered as a proxy of the ecosystem provisioning services. To this end, we used a 14-year dataset on benthic invertebrate community production from a seagrass and a sandflat habitat and we adopted a sequential modeling approach, where abiotic, trait community weighted means (CWM and functional diversity indices were tested by generalized linear models (GLM, and their significant variables were then combined to produce a final model. Almost 90% of variance of the benthic production could be predicted by combining the number of locomotion types, the absolute maximum atmospheric temperature (proxy of the heat waves occurrence, the type of habitat and the mean body mass, by order of importance. This result is in agreement with the mass ratio hypothesis, where ecosystem functions/services can be chiefly predicted by the dominant trait in the community, here measured as CWM. The increase of benthic production with the number of locomotion types may be seen as greater possibility of using the resources available in the system. Such greater efficiency would increase production. The other variables were also discussed in line of the previous hypothesis and taking into account the general positive relationship obtained between production and functional diversity indices. Overall, it was concluded that traits representative of wider possibilities of using available resources and higher functional diversity are related with higher benthic production.

  18. Box-modeling of the impacts of atmospheric nitrogen deposition and benthic remineralization on the nitrogen cycle of the eastern tropical South Pacific

    Science.gov (United States)

    Su, B.; Pahlow, M.; Oschlies, A.

    2015-09-01

    Both atmospheric deposition and benthic remineralization influence the marine nitrogen cycle, and hence ultimately also marine primary production. The biological and biogeochemical relations of the eastern tropical South Pacific (ETSP) to nitrogen deposition, benthic denitrification and phosphate regeneration are analysed in a prognostic box model of the oxygen, nitrogen and phosphorus cycles in the ETSP. In the model, atmospheric nitrogen deposition based on estimates for the years 2000-2009 is offset by half by reduced N2 fixation, with the other half transported out of the model domain. Both model- and data-based benthic denitrification are found to trigger nitrogen fixation, partly compensating for the NO3- loss. Since phosphate is the ultimate limiting nutrient in the model, enhanced sedimentary phosphate regeneration under suboxic conditions stimulates primary production and subsequent export production and NO3- loss in the oxygen minimum zone (OMZ). A sensitivity analysis of the local response to both atmospheric deposition and benthic remineralization indicates dominant stabilizing feedbacks in the ETSP, which tend to keep a balanced nitrogen inventory, i.e., nitrogen input by atmospheric deposition is counteracted by decreasing nitrogen fixation; NO3- loss via benthic denitrification is partly compensated by increased nitrogen fixation; enhanced nitrogen fixation stimulated by phosphate regeneration is partly removed by the stronger water-column denitrification. Even though the water column in our model domain acts as a NO3- source, the ETSP including benthic denitrification might become a NO3- sink.

  19. Box-modeling of the impacts of atmospheric nitrogen deposition and benthic remineralization on the nitrogen cycle of the eastern tropical South Pacific

    Directory of Open Access Journals (Sweden)

    B. Su

    2015-09-01

    Full Text Available Both atmospheric deposition and benthic remineralization influence the marine nitrogen cycle, and hence ultimately also marine primary production. The biological and biogeochemical relations of the eastern tropical South Pacific (ETSP to nitrogen deposition, benthic denitrification and phosphate regeneration are analysed in a prognostic box model of the oxygen, nitrogen and phosphorus cycles in the ETSP. In the model, atmospheric nitrogen deposition based on estimates for the years 2000–2009 is offset by half by reduced N2 fixation, with the other half transported out of the model domain. Both model- and data-based benthic denitrification are found to trigger nitrogen fixation, partly compensating for the NO3− loss. Since phosphate is the ultimate limiting nutrient in the model, enhanced sedimentary phosphate regeneration under suboxic conditions stimulates primary production and subsequent export production and NO3− loss in the oxygen minimum zone (OMZ. A sensitivity analysis of the local response to both atmospheric deposition and benthic remineralization indicates dominant stabilizing feedbacks in the ETSP, which tend to keep a balanced nitrogen inventory, i.e., nitrogen input by atmospheric deposition is counteracted by decreasing nitrogen fixation; NO3− loss via benthic denitrification is partly compensated by increased nitrogen fixation; enhanced nitrogen fixation stimulated by phosphate regeneration is partly removed by the stronger water-column denitrification. Even though the water column in our model domain acts as a NO3− source, the ETSP including benthic denitrification might become a NO3− sink.

  20. Flow of light energy in benthic photosynthetic microbial mats

    Energy Technology Data Exchange (ETDEWEB)

    Al-Najjar, Mohammad Ahmad A.

    2010-12-15

    The work in this thesis demonstrates the assessment of the energy budget inside microbial mat ecosystems, and the factors affecting light utilization efficiency. It presents the first balanced light energy budget for benthic microbial mat ecosystems, and shows how the budget and the spatial distribution of the local photosynthetic efficiencies within the euphotic zone depend on the absorbed irradiance (Jabs). The energy budget was dominated by heat dissipation on the expense of photosynthesis. The maximum efficiency of photosynthesis was at light limiting conditions When comparing three different marine benthic photosynthetic ecosystems (originated from Abu-Dhabi, Arctic, and Exmouth Gulf in Western Australia), differences in the efficiencies were calculated. The results demonstrated that the maximum efficiency depended on mat characteristics affecting light absorption and scattering; such as, photopigments ratio and distribution, and the structural organization of the photosynthetic organisms relative to other absorbing components of the ecosystem (i.e., EPS, mineral particles, detritus, etc.). The maximum efficiency decreased with increasing light penetration depth, and increased with increasing the accessory pigments (phycocyanin and fucoxanthin)/chlorophyll ratio. Spatial heterogeneity in photosynthetic efficiency, pigment distribution, as well as light acclimation in microbial mats originating from different geographical locations was investigated. We used a combined pigment imaging approach (variable chlorophyll fluorescence and hyperspectral imaging), and fingerprinting approach. For each mat, the photosynthetic activity was proportional to the local pigment concentration in the photic zone, but not for the deeper layers and between different mats. In each mat, yield of PSII and E1/2 (light acclimation) generally decreased in parallel with depth, but the gradients in both parameters varied greatly between samples. This mismatch between pigments concentration

  1. Comparison of ecological diversity and species composition of macroalgae, benthic macroinvertebrates, and fish assemblages between two tropical rocky reefs

    OpenAIRE

    Verónica C. García-Hernández; Héctor Reyes-Bonilla; Balart, Eduardo F; Eduardo Ríos-Jara; Lluch-Cota, Salvador E.; Elisa Serviere-Zaragoza

    2014-01-01

    Within the marine environment, the rocky shores are recognized for their high species diversity and particularly transitional zones represent areas of biotic mix, promoted by historical and ecological natural variations that allow the presence of taxa from different regions and which present dissimilar biological traits. An extensive survey describes the benthic macroalgae, macroinvertebrates (molluscs, crustaceans, and echinoderms), and fish assemblages at two rocky reefs, Islas Marietas and...

  2. Planktonic and benthic foraminiferal biostratigraphy of the Middle Eocene-Lower Miocene successions from the Sivas Basin (Central Anatolia, Turkey)

    Science.gov (United States)

    Hakyemez, Aynur; Özgen-Erdem, Nazire; Kangal, Özgen

    2016-02-01

    Planktonic and benthic foraminifera are described from the Middle Eocene-Lower Miocene successions in the Sivas Basin, Central Anatolia. An integrated foraminiferal zonation provides new age assignments in terms of a great number of taxa for the studied sections. Four biostratigraphical intervals are first recorded based on the concurrent ranges of sporadically occurring but well preserved planktonic foraminiferal assemblages. The first interval characterized by the co-occurrences of Acarinina bullbrooki, Truncorotaloides topilensis and Turborotalia cerroazulensis is referable to the E11 Zone of late Lutetian-early Bartonian. An assemblage yielding Paragloborotalia opima accompanied by Globigerinella obesa forms a basis for the late Chattian O5 Zone. The successive interval corresponds to the late Chattian O6 Zone indicated by the presence of Globigerina ciperoensis and Globigerinoides primordius along with the absence of Paragloborotalia opima. The early Aquitanian M1 Zone can be tentatively defined based mainly on the assemblage of Globigerina, Globigerinella, Globoturborotalita and Tenuitella. The biostratigraphical data obtained from the benthic foraminifera assign the studied sections to the SBZ 21-22, SBZ 23 and SBZ 24 ranging in age from Rupelian to Aquitanian. The SBZ 23 and 24 are well constrained biozones by the occurrences of Miogypsinella complanata and Miogypsina gunteri, respectively, whereas the SBZ 21-22 defined by nummulitids and lepidocylinids in the Tethyan Shallow Benthic Zonation is characterized dominantly by peneroplids, soritids and miliolids in the studied sections. Benthic foraminiferal assemblages suggest different paleoenvironments covering lagoon, algal reef and shallow open marine whereas planktonic foraminifera provides evidence for relatively deep marine settings on the basis of assemblages characterized by a mixture of small-sized simple and more complex morphogroups indicative for intermediate depths of the water column.

  3. Effects of fluctuating hypoxia on benthic oxygen consumption in the Black Sea (Crimean shelf)

    Science.gov (United States)

    Lichtschlag, A.; Donis, D.; Janssen, F.; Jessen, G. L.; Holtappels, M.; Wenzhöfer, F.; Mazlumyan, S.; Sergeeva, N.; Waldmann, C.; Boetius, A.

    2015-08-01

    The outer western Crimean shelf of the Black Sea is a natural laboratory to investigate effects of stable oxic versus varying hypoxic conditions on seafloor biogeochemical processes and benthic community structure. Bottom-water oxygen concentrations ranged from normoxic (175 μmol O2 L-1) and hypoxic (< 63 μmol O2 L-1) or even anoxic/sulfidic conditions within a few kilometers' distance. Variations in oxygen concentrations between 160 and 10 μmol L-1 even occurred within hours close to the chemocline at 134 m water depth. Total oxygen uptake, including diffusive as well as fauna-mediated oxygen consumption, decreased from 15 mmol m-2 d-1 on average in the oxic zone, to 7 mmol m-2 d-1 on average in the hypoxic zone, correlating with changes in macrobenthos composition. Benthic diffusive oxygen uptake rates, comprising respiration of microorganisms and small meiofauna, were similar in oxic and hypoxic zones (on average 4.5 mmol m-2 d-1), but declined to 1.3 mmol m-2 d-1 in bottom waters with oxygen concentrations below 20 μmol L-1. Measurements and modeling of porewater profiles indicated that reoxidation of reduced compounds played only a minor role in diffusive oxygen uptake under the different oxygen conditions, leaving the major fraction to aerobic degradation of organic carbon. Remineralization efficiency decreased from nearly 100 % in the oxic zone, to 50 % in the oxic-hypoxic zone, to 10 % in the hypoxic-anoxic zone. Overall, the faunal remineralization rate was more important, but also more influenced by fluctuating oxygen concentrations, than microbial and geochemical oxidation processes.

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

    Science.gov (United States)

    Loubere, Paul; Rayray, Shan

    2016-09-01

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

  5. Prediction of benthic community structure from environmental variables in a soft-sediment tidal basin (North Sea)

    Science.gov (United States)

    Puls, W.; van Bernem, K.-H.; Eppel, D.; Kapitza, H.; Pleskachevsky, A.; Riethmüller, R.; Vaessen, B.

    2012-09-01

    The relationship between benthos data and environmental data in 308 samples collected from the intertidal zone of the Hörnum tidal basin (German Wadden Sea) was analyzed. The environmental variables were current velocity, wave action, emersion time (all of which were obtained from a 2-year simulation with a numerical model) and four sediment grain-size parameters. A grouping of sample stations into five benthos clusters showed a large-scale (>1 km) zoning of benthic assemblages on the tidal flats. The zoning varied with the distance from the shore. Three sample applications were examined to test the predictability of the benthic community structure based on environmental variables. In each application, the dataset was spatially partitioned into a training set and a test set. Predictions of benthic community structure in the test sets were attempted using a multinomial logistic regression model. Applying hydrodynamic predictors, the model performed significantly better than it did when sediment predictors were applied. The accuracy of model predictions, given by Cohen's kappa, varied between 0.14 and 0.49. The model results were consistent with independently attained evidence of the important role of physical factors in Wadden Sea tidal flat ecology.

  6. Benthic invertebrate fauna in the islets of Namuseom and Bukhyeongjeseom off Busan

    Directory of Open Access Journals (Sweden)

    Hosung Hwang

    2014-06-01

    Full Text Available This study was conducted to examine the benthic invertebrate fauna inhabiting in the subtidal zone in and around the islets of Namuseom and Bukhyeongjeseom off the coast of Busan by SCUBA diving in September 2013. As a consequence, it was confirmed that a total of 6 phyla, 14 classes, 20 orders, 46 families, and 73 species of zoobenthos inhabit in and around those islets. The total number of species surveyed by taxon during the study is 22 species of Arthropoda (30%, 20 species of Mollusca (27%, 15 species of Cnidaria (21%, 10 species of Echinodermata (14%, four species of Poridera (5%, and two species of Chordata.

  7. Benthic invertebrate fauna in the islets of Namuseom and Bukhyeongjeseom off Busan

    OpenAIRE

    Hosung Hwang; Jisoon Kang; In-Young Cho; Dong-Won Kang; Woon Kee Paek; Seok Hyun Lee

    2014-01-01

    This study was conducted to examine the benthic invertebrate fauna inhabiting in the subtidal zone in and around the islets of Namuseom and Bukhyeongjeseom off the coast of Busan by SCUBA diving in September 2013. As a consequence, it was confirmed that a total of 6 phyla, 14 classes, 20 orders, 46 families, and 73 species of zoobenthos inhabit in and around those islets. The total number of species surveyed by taxon during the study is 22 species of Arthropoda (30%), 20 species of Mollusca (...

  8. Benthic-Pelagic Coupling in Biogeochemical and Climate Models: Existing Approaches, Recent developments and Roadblocks

    Science.gov (United States)

    Arndt, Sandra

    2016-04-01

    Marine sediments are key components in the Earth System. They host the largest carbon reservoir on Earth, provide the only long term sink for atmospheric CO2, recycle nutrients and represent the most important climate archive. Biogeochemical processes in marine sediments are thus essential for our understanding of the global biogeochemical cycles and climate. They are first and foremost, donor controlled and, thus, driven by the rain of particulate material from the euphotic zone and influenced by the overlying bottom water. Geochemical species may undergo several recycling loops (e.g. authigenic mineral precipitation/dissolution) before they are either buried or diffuse back to the water column. The tightly coupled and complex pelagic and benthic process interplay thus delays recycling flux, significantly modifies the depositional signal and controls the long-term removal of carbon from the ocean-atmosphere system. Despite the importance of this mutual interaction, coupled regional/global biogeochemical models and (paleo)climate models, which are designed to assess and quantify the transformations and fluxes of carbon and nutrients and evaluate their response to past and future perturbations of the climate system either completely neglect marine sediments or incorporate a highly simplified representation of benthic processes. On the other end of the spectrum, coupled, multi-component state-of-the-art early diagenetic models have been successfully developed and applied over the past decades to reproduce observations and quantify sediment-water exchange fluxes, but cannot easily be coupled to pelagic models. The primary constraint here is the high computation cost of simulating all of the essential redox and equilibrium reactions within marine sediments that control carbon burial and benthic recycling fluxes: a barrier that is easily exacerbated if a variety of benthic environments are to be spatially resolved. This presentation provides an integrative overview of

  9. Bathymetric and regional changes in benthic macrofaunal assemblages on the deep Eastern Brazilian margin, SW Atlantic

    Science.gov (United States)

    Bernardino, Angelo Fraga; Berenguer, Vanessa; Ribeiro-Ferreira, Venina P.

    2016-05-01

    Deep-sea continental slopes have valuable mineral and biological resources in close proximity to diverse, undersampled and fragile marine benthic ecosystems. The eastern Brazilian Continental Margin (19.01°S to 21.06°S, 37.88°W to 40.22°W) is an important economic region for both fishing and oil industries, but is poorly understood with respect to the structure of the soft-sediment benthic fauna, their regional distribution and their bathymetric patterns. To identify spatial and temporal patterns of benthic macrofaunal assemblages on the slope (400 to 3000 m), the Espirito Santo Basin Assessment Project (AMBES, coordinated by Cenpes-Petrobras) sampled 42 stations across the Brazilian Eastern Slope during both Summer 2012 and Winter 2013. We found a significant decrease in macrofaunal abundance at the 400 m isobath along the slope near the northern region of the Espirito Santo Basin, suggesting benthic responses to upwelling events towards the south in Campos Basin and southern Espirito Santo Basin. The taxonomic diversity and assemblage composition also changed significantly across depth zones with mid-slope peaks of diversity at 1000-1300 m. In general, macrofaunal assemblages were strongly related to slope depth, suggesting a strong influence of productivity gradients and water mass distribution on this oligotrophic margin. Sediment grain size was marginally important to macrofaunal composition on the upper slope. In general, macrofaunal assemblages on the slope of Espirito Santo Basin are similar to other areas of the SE Brazilian margin, but regional changes in response to productivity and depth need to be considered for management strategies in the face of increasing economic activities off-shore.

  10. A comparison of benthic infaunal abundance on two abyssal plains in the northeast Pacific Ocean

    Science.gov (United States)

    Carey, Andrew G.

    1981-05-01

    Benthic macro-infauna were sampled in the northeast Pacific Ocean at 12 stations on an east-west transect across Cascadia and Eastern Tufts abyssal plains to determine ecological effects of continental influences and depth on those communities. The two plains, separated by the East Pacific Rise, differ in depth and distance from the continental margin. Tufts Plain lies to the west; primary production in the overlying water and the amount of organic carbon in the surface sediments are lower than for the Cascadia Plain region. Five benthic ecological zones were distinguished: (1) Cascadia Plain Slope-Base; (2) Eastern Cascadia Plain; (3) Cascadia Deep-Sea Channel; (4) Western Cascadia Plain; and (5) Eastern Tufts Plain. These differ in faunal biomass, numerical density, gross composition of the fauna by phyla, and composition of sediment. Comparatively, the slope-base environment supports the most abundant fauna. The numerical density of infauna on Eastern Tufts Plain is similar to that on Eastern and Western Cascadia Plain; however, the biomass tends to be lower in the deeper, more distant environment. It is concluded that these differences in the benthic fauna are probably caused by varying levels of input from primary production in overlying waters and differences in the transport of organic-rich particles off the continental shelf. Distance-related environmental characteristics are shown to be critical in the deep sea for controlling benthic community structure. On Cascadia Abyssal Plain, a plateau-like feature, the gross structure of communities changes with increasing distance from the continent but at constant depth. Faunal densities, biomass, and composition by phyla lie within the range of values normally associated with upper abyssal environments.

  11. Benthic Habitat Mapping and Biodiversity Analysis in the Primeiras and Segundas Archipelago Reserve

    Science.gov (United States)

    Teixeira, L.; Nilsson, M.; Hedley, J.; Shapiro, A.

    2015-04-01

    The Primeiras and Segundas Archipelago Reserve is a recently established marine protected area, the largest in Africa, located in the waters of Northern Mozambique. This protected area is of significant local economic importance and global ecological relevance, containing the southernmost coral reefs in Eastern Africa. However, information related to the marine ecosystem, notably benthic habitat is very scarce. Twelve atolls were mapped in the region using object-based image classification of very-high resolution satellite imagery (IKONOS, Quickbird, and WorldView-2). Geographically referenced data on benthic cover and depth were gathered in the course of three fieldwork expeditions covering a total of four atolls and two shallow reef structures in the Segundas Archipelago. The resulting map allows the estimation of three distinct types of coral cover (field, patches, spurs and grooves); the differentiation of sand, rubble and rock substrate; and the detection of seagrass and brown macroalgae, identifying up to 24 benthic habitats. Average overall accuracy was above 50%. The high variability of the optical properties on the reef systems, in large due to the connectivity with the mainland via plumes, while interesting from an ecological perspective increases the challenges for remote sensing of bottom cover. New information indicates the presence of deep benthic cover extending from the atolls, suggesting the need for further research on Coastal Eastern African corals, namely on their resilience and connectivity, and supporting current knowledge of the existence of an almost continuous coral reef from Kenya to Mozambique. Coral and fish biodiversity data have been analysed together with the satellite-derived maps. Results support the local perception that ecosystems are in decline and uncover new information about biodiversity's spatial patterns. Our work provides a detailed depiction of marine habitats that may aid the management of the protected area, namely in

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

    Science.gov (United States)

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

    2016-01-01

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

  13. Benthic macroinvertebrates in Italian rice fields

    Directory of Open Access Journals (Sweden)

    Daniela Lupi

    2013-02-01

    Full Text Available Rice fields can be considered man-managed temporary wetlands. Five rice fields handled with different management strategies, their adjacent channels, and a spring were analysed by their benthic macroinvertebrate community to i evaluate the role of rice agroe- cosystem in biodiversity conservation; ii find indicator species which can be used to compare the ecological status of natural wetlands with rice agroecosystems; and iii find the influence of environmental variables on biodiversity. Different methods of data analysis with increasing degree of complexity – from diversity index up to sophisticated multivariate analysis – were used. The investigation provided a picture of benthic macroinvertebrates inhabiting rice agroecosystems where 173 taxa were identified, 89 of which detected in rice paddies. Among them, 4 phyla (Mollusca, Annelida, Nematomorpha, and Arthropoda, 8 classes (Bivalvia, Gastropoda, Oligochaeta, Hirudinea, Gordioida, Insecta, Branchiopoda, and Malacostraca, 24 orders, 68 families, 127 genera and 159 species have been found. Ten threatened and 3 invasive species were detected in the habitats examined. The information obtained by the different methods of data analysis allowed a more comprehensive view on the value of the components of rice agroecosystems. Data analyses highlighted significant differences between habitats (feeding channel and rice field, with higher diversity observed in channels, and emphasised the role of the water chemical-physical parameters. The period of water permanence in rice fields resulted to be only one of the factors influencing the community of benthic macroinvertebrates. The presence of rare/endangered species allowed characterising some stations, but it was less informative about management strategies in rice paddies because most of these species were absent in rice fields.

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

    Science.gov (United States)

    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...

  15. Benthic Macroinvertebrate Communities in Agriculturally Impaired Streams

    Directory of Open Access Journals (Sweden)

    Virginija Pliuraite

    2009-10-01

    Full Text Available Normal 0 false false false EN-US X-NONE X-NONE This work presents research into the taxonomic composition of macroinvertebrate communities in streams that are under the influence of agricultural pollution A total of 67 macroinvertebrate taxa (including 61 identified species belonging to 40 families have been identified in the explored streams. The greatest species richness is recorded for the Trichoptera (18 species/1 taxa and Mollusca (12 species. The molluscs Gyraulus albus, amphipods Gammarus pulex, caddisflies Hydropsyche pellucidula and oligochaetes are detected in all examined streams. There, the number of total benthic macroinvertebrate taxa is highly variable, ranging from 16 to 40. Results show that the examined streams depending on the benthic macroinvertebrate taxonomic composition and predominance of seperate macroinvertebrate groups undergo different pollution. Intolerant to pollution taxa such as Plecoptera, which are the most sensitive to pollution insects, have been found only in 5 of 12 examined streams and in low abundances. The richness and diversity of macrozoobenthos in some streams appear to respond to the water quality deterioration. The present study has found out that in the stream where the total macroinvertebrate taxa, EPT taxa richness are the lowest and a relative abundance of gatherers is the highest, the values of NH4-N, NO3-N, total N, PO4-P and total P in the stream water are the highest, too.

  16. Delimiting oceanographic provinces to determine drivers of mesoscale patterns in benthic megafauna: A case study in the Barents Sea

    Science.gov (United States)

    Lacharité, Myriam; Jørgensen, Lis Lindal; Metaxas, Anna; Lien, Vidar S.; Skjoldal, Hein Rune

    2016-08-01

    Communities of benthic megafauna in the deep waters of continental shelves (> 100 m) are important components of marine ecosystems. In high-latitude ecosystems, this fauna is increasingly impacted by human activities and climate variability. In this study, we provide baseline knowledge on the oceanographic conditions affecting its distribution in the Barents Sea in the vicinity of the Polar Front - an oceanic front occurring at the transition zone between the Atlantic and Arctic water masses. We used fields of temperature and currents from an ocean circulation model (Regional Ocean Modelling System - ROMS) to derive variables divided into 3 groups relevant to bottom fauna (temperature, water column structure and bottom currents) expressing either mean conditions or temporal variability over 10 years (2001-2010). Benthic megafauna was surveyed in summer 2011 at 139 sites. To analyze the relationship between spatial variability in the composition of benthic megafauna (i.e., β-diversity) and oceanographic conditions, we: (1) used generalized dissimilarity modelling (GDM) and (2) delimited oceanographic provinces (i.e., regions of similar conditions) for each group of variables using principal component analysis (PCA) followed by cluster analysis. Turnover in benthic megafauna was explained by 7 oceanographic variables (temperature: 4, water column structure: 2, bottom currents: 1), depth and geographic distance (56.7% of total deviance explained). Concurrently, patterns in oceanographic provinces among the 3 groups of variables coincided with results from the GDM, where provinces derived from temperature were sharply delimited relative to the other groups. We concluded that the spatial structure of the environment is important in the relationship between spatial variability of benthic megafauna and oceanographic conditions in shelf deep waters. Ocean models are powerful tools to study this relationship, but the way in which their inherent uncertainty affects the

  17. Benthic indicators: From subjectivity to objectivity - Where is the line?

    Science.gov (United States)

    Dauvin, Jean-Claude; Bellan, Gérard; Bellan-Santini, Denise

    2010-07-01

    Over the last few years, the interest in using benthic indicators to assess marine environments has increased dramatically after a rather long period of relative stagnation, mostly due to the need to assess the status of coastal marine waters required by North American and European regulations. Numerous papers on this topic have been published in the domain of ecology, using a variety of different terms to refer to two categories of information: benthic species and the status of benthic communities. Nowadays, the abundant literature on these two categories makes it possible to comment on (1) the definition of the different terms used by benthic researchers, (2) the current increase of papers of rising complexity about benthic indicators, and (3) the subjectivity and objectivity involved in using benthic indicators. Faced with the increase in the number of methods, we recommend pragmatism and thus the transfer of simple methods to the research consultancies that are responsible for assessing benthic quality in numerous impact studies. Using certain procedures, such as the "sentinel species", the best professional judgement (BPJ) and taxonomic sufficiency (TS), should clearly be encouraged. PMID:20413132

  18. Spatiotemporal changes in surface sediment characteristics and benthic macrofauna composition off the Rhône River in relation to its hydrological regime

    Science.gov (United States)

    Bonifácio, Paulo; Bourgeois, Solveig; Labrune, Céline; Amouroux, Jean Michel; Escoubeyrou, Karine; Buscail, Roselyne; Romero-Ramirez, Alicia; Lantoine, François; Vétion, Gilles; Bichon, Sabrina; Desmalades, Martin; Rivière, Béatrice; Deflandre, Bruno; Grémare, Antoine

    2014-12-01

    The consequences of changes in the water flow of the Rhône River on surface sediment characteristics and benthic macrofauna composition were assessed within 3 distinct areas: (1) the delta front, (2) the prodelta, and (3) the distal zone. Five stations were sampled during or closely after: (1) an oceanic flood (April 2007), (2) a generalized flood (May 2008), (3) a Cevenol flood (December 2008), and (4) a dry period (July 2011). Measurements of sediment characteristics included granulometry (D0.5), bulk descriptors of sedimentary organics (OC, TN and THAA), descriptors of labile components of sedimentary organics (chloropigments, EHAA), and both descriptors of origin (Chl-b/Chl-a, C/N) and lability (Chl-a/(Chl-a+Phaeo-a), EHAA/THAA) of sedimentary organics. Sediment Profile Images were collected during April 2007, May 2008 and July 2011. Temporal changes in both sedimentary organics and benthic macrofauna were more important in the delta front and the prodelta than in the distal zone. Bulk characteristics of sedimentary organics presented decreasing inshore/offshore gradients during both April 2007 and July 2011 but not during May and December 2008. There were significant temporal changes in EHAA/THAA at all stations. Changes in benthic macrofauna composition differed between: (1) the delta front and the prodelta, and (2) the distal zone. In the former area, the dry period was associated with establishing a mature community characterized by high abundances and species richness. The best description of spatiotemporal changes in benthic macrofauna composition by surface sediment characteristics was obtained using D0.5, Chl-b/Chl-a, Chl-a/(Chl-a+Phaeo-a) and EHAA, which supports the role of the quality of sedimentary organics in controlling benthic macrofauna composition.

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

    Science.gov (United States)

    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

  20. Landslide-induced iron mobilisation shapes benthic accumulation of nutrients, trace metals and REE fractionation in an oligotrophic alpine stream

    Science.gov (United States)

    Johnston, Scott G.; Rose, Andrew L.; Burton, Edward D.; Webster-Brown, Jenny

    2015-01-01

    Large alpine landslides that entrain substantial organic material below the water table and create suspended floodplains may have long-term consequences for the mobilisation of redox sensitive elements, such as Fe, into streamwaters. In turn, the cycling of iron in aquatic systems can influence the fate of nutrients, alter primary productivity, enhance accumulation of trace metals and induce fractionation of rare earth elements (REE). In this study we examine a reach of a pristine oligotrophic alpine stream bracketing a 30 year-old landslide and explore the consequences of landslide-induced Fe mobilisation for aqueous geochemistry and the composition of benthic stream cobble biofilm. Elevated Fe2+ and Mn in landslide zone stream waters reflect inputs of circumneutral groundwater from the landslide debris-zone floodplain. Geochemical characteristics are consistent with reductive dissolution being a primary mechanism of Fe2+ and Mn mobilisation. Stream cobble biofilm in the landslide zone is significantly (P stream length, we estimate it is responsible for approximately 60-80% of the stream's benthic biofilm load of poorly crystalline Fe(III) and Mn. Biofilm Fe(III) precipitates are comprised mainly of ferrihydrite, lepidocrocite and an organic-Fe species, while precipitate samples collected proximal to hyporheic seeps contain abundant sheath structures characteristic of the neutrophilic Fe(II)-oxidising bacteria Leptothrix spp. Stream-cobble Fe(III)-rich biofilm is accumulating PO43- (∼3-30 times background) and behaving as a preferential substrate for photosynthetic periphyton, with benthic PO43-, chlorophyll a, organic carbonHCl and total N all significantly positively correlated with Fe(III)Ab and significantly elevated within the landslide zone (P Stream cobble biofilm also exhibits distinct REE fractionation along the flow path, with light REE (La, Ce, Nd, Pr) preferentially partitioning to the Fe(III) and Mn-rich biofilm within the landslide zone

  1. Spatial and temporal heterogeneity in a subtropical reservoir and their effects over the benthic macroinvertebrate community

    Directory of Open Access Journals (Sweden)

    Frederico Guilherme de Souza Beghelli

    2014-09-01

    Full Text Available AIM: The objective of the present study was to demonstrate the influences of the environment spatial heterogeneity on benthic macroinvertebrates considering transverse and longitudinal gradients as also seasonality. METHODS: Four samplings were performed: two in the wet and two in the dry season in the riverine, transitional and lacustrine zones in the littoral and profundal regions of Itupararanga reservoir, SP, Brazil. Abiotic characterization of the water and of the sediment was performed. The biotic characterization was based on richness, dominance, diversity, and density of organisms, as well as on the relative abundance of predominant taxa. Two-way ANOSIM analyses were performed for both biotic and abiotic components, in order to test the significance of the differences in the longitudinal and transverse directions as well as of the differences between seasons. RESULTS: Compartmentalization was present in both directions, longitudinal and transverse. In a general way, the littoral region presented higher diversity values when compared with the profundal region, and the riverine zone presented high densities and high percentage of taxons, which usually indicate organic pollution. The differentiation between the transitional and lacustrine zones was determined mainly by taxonomic composition. Seasonality was also observed and the transportation of small particles, the entrance of nutrients, and the presence of macrophytes were considered as determinants for differentiation. CONCLUSIONS: Together, these results demonstrate the responses of benthic macroinvertebrate communities considering distinct sources of variation: longitudinal heterogeneity, determined by the increasing distance from the forming rivers that leads to a gradient of physical and chemical conditions; transverse heterogeneity, determined by the proximity with the land environment and depth differences. Seasonal heterogeneity was recorded during the period of this research and

  2. Vieques, Puerto Rico Benthic Habitat Map - Accuracy Assessment Sites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic habitat maps of the nearshore marine environment of Vieques, Puerto Rico were created by visual interpretation of remotely sensed imagery. The objective of...

  3. Coastal Bend Texas Benthic Habitat - San Antonio Bay 2007 Biotic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  4. Coastal Bend Texas Benthic Habitat - Lower Laguna Madre 2004 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  5. Coastal Bend Texas Benthic Habitat - Lower Laguna Madre 2004 Geodatabase

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  6. Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Geoform

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

  7. Coastal Bend Texas Benthic Habitat - San Antonio Bay 2007 Geoform

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  8. Coastal Bend Texas Benthic Habitat - San Antonio Bay 2007 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  9. Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Geodatabase

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

  10. Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Biotic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

  11. Coastal Bend Texas Benthic Habitat - Lower Laguna Madre 2004 Biotic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  12. Coastal Bend Texas Benthic Habitat - Lower Laguna Madre 2004 Geoform

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  13. Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay 2007 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing and new digital multi-spectral imagery and create digital benthic...

  14. Coastal Bend Texas Benthic Habitat - San Antonio Bay 2007 Geodatabase

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  15. Vieques, Puerto Rico Benthic Habitat Map - Ground Validation Sites

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic habitat maps of the nearshore marine environment of Vieques, Puerto Rico were created by visual interpretation of remotely sensed imagery. The objective of...

  16. Shallow-water Benthic Habitats in Jobos Bay

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of Jobos Bay, Puerto Rico were mapped and characterized using visual interpretation...

  17. Benthic grab data from October 1999 in Apalachicola Bay, Florida

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Apalachicola Bay National Estuarine Research Reserve and the NOAA Office for Coastal Management worked together to map benthic habitats within Apalachicola Bay,...

  18. Evidence for complete denitrification in a benthic foraminifer

    DEFF Research Database (Denmark)

    Risgaard-Petersen, Nils; Langezaal, Alexandra; Ingvardsen, Signe; Schmid, Markus; Derksen, Jan W.M.; Op den Camp, Huup; Pina-Ochoa, Elisa; Eriksson, Susanne; Nielsen, Lars Peter; Revsbech, Niels Peter; Cedhagen, Tomas; van der Zwaan, Gilbert J.

    2006-01-01

    Benthic foraminifera are unicellular eukaryotes found abundantly in many types of marine sediments. Many species survive and possibly reproduce in anoxic habitats1, but sustainable anaerobic metabolism has not been previously described. Here we demonstrate that the foraminifer Globobulimina pseud...

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

    Science.gov (United States)

    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...

  20. Estimation of sediment properties during benthic impact experiments

    Digital Repository Service at National Institute of Oceanography (India)

    Yamazaki, T.; Sharma, R.

    Sediment properties, such as water content and density, have been used to estimate the dry and wet weights, as well as the volume of sediment recovered and discharged, during benthic impact experiments conducted in the Pacific and Indian Oceans...

  1. Northeast Puerto Rico and Culebra Island - Benthic Habitat Map 2015

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This benthic habitat map was created from a semi-automated habitat mapping process, using a combination of bathymetry, satellite imagery, aerial imagery and...

  2. Coastal Bend Texas Benthic Habitat Mapping Redfish Bay 2004 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  3. Coastal Bend Texas Benthic Habitat Mapping Aransas Bay 2004 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  4. Atlantic Deep-Water Canyons (Benthic Landers) 2013

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Each benthic lander contains a programmable sediment trap which can take 12 monthly samples, plus instruments to record temperature, salinity, dissolved oxygen,...

  5. USVI Land-Based Threat to Benthic Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set describes the potential threat of sediment delivery and land-based sources of pollution to benthic habitats. This dataset is derived from NOAA's...

  6. Coastal Bend Texas Benthic Habitat Mapping Patchy Shapefile Map

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  7. Metal incorporation by benthic fauna: relationships to sediment inventory

    International Nuclear Information System (INIS)

    A radionuclide addition experiment was conducted in a large-scale experimental mesocosm to study the behaviour and fate of trace metals in a coastal marine environment. Twelve radionuclides (7Be, 109Cd, 134Cs, 58Co, 60Co, 51Cr, 59Fe, 54Mn, 203Hg, 233Pa, 113Sn, and 65Zn) were added and their concentrations in benthic organisms and sediments were measured during the following nine months. The ability of benthic organisms to concentrate radionuclides was related to the vertical distribution and feeding behaviour of the organisms. Surface living fauna incorporated more radionuclides than deeper fauna. Calculations of total annual radionuclide incorporation by benthic fauna indicated that meiofauna incorporated a similar amount of the labelled metals as the macrofauna, even though the latter have a larger standing stock biomass. These calculations suggest that benthic metazoan fauna can annually cycle from 1% (Sn) to nearly 50% (Cd) of the amount of added radionuclides measured in sediments. (author)

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

    Science.gov (United States)

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

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

    Science.gov (United States)

    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...

  10. Puerto Rico Land-Based Threat to Benthic Habitats

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set describes the potential threat of sediment delivery and land-based sources of pollution to benthic habitats. This dataset is derived from NOAA's...

  11. Shallow-Water Benthic Habitats of Southwest Puerto Rico

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of two areas in Southwest Puerto Rico (PR), including the Guanica Bay/La Parguera...

  12. Benthic ammonia oxidizers differ in community structure and biogeochemical potential across a riverine delta.

    Science.gov (United States)

    Damashek, Julian; Smith, Jason M; Mosier, Annika C; Francis, Christopher A

    2014-01-01

    Nitrogen pollution in coastal zones is a widespread issue, particularly in ecosystems with urban or agricultural watersheds. California's Sacramento-San Joaquin Delta, at the landward reaches of San Francisco Bay, is highly impacted by both agricultural runoff and sewage effluent, leading to chronically high nutrient loadings. In particular, the extensive discharge of ammonium into the Sacramento River has altered this ecosystem by vastly increasing ammonium concentrations and thus changing the stoichiometry of inorganic nitrogen stocks, with potential effects throughout the food web. This debate surrounding ammonium inputs highlights the importance of understanding the rates of, and controls on, nitrogen (N) cycling processes across the delta. To date, however, there has been little research examining N biogeochemistry or N-cycling microbial communities in this system. We report the first data on benthic ammonia-oxidizing microbial communities and potential nitrification rates for the Sacramento-San Joaquin Delta, focusing on the functional gene amoA (which codes for the α-subunit of ammonia monooxygenase). There were stark regional differences in ammonia-oxidizing communities, with ammonia-oxidizing bacteria (AOB) outnumbering ammonia-oxidizing archaea (AOA) only in the ammonium-rich Sacramento River. High potential nitrification rates in the Sacramento River suggested these communities may be capable of oxidizing significant amounts of ammonium, compared to the San Joaquin River and the upper reaches of San Francisco Bay. Gene diversity also showed regional patterns, as well as phylogenetically unique ammonia oxidizers in the Sacramento River. The benthic ammonia oxidizers in this nutrient-rich aquatic ecosystem may be important players in its overall nutrient cycling, and their community structure and biogeochemical function appear related to nutrient loadings. Unraveling the microbial ecology and biogeochemistry of N cycling pathways, including benthic

  13. A survey of benthic assemblages of foraminifera in tropical coastal waters of pulau pinang, malaysia.

    Science.gov (United States)

    Minhat, Fatin Izzati; Yahya, Khairun; Talib, Anita; Ahmad, Omar

    2013-08-01

    The distribution of benthic Foraminifera throughout the coastal waters of Taman Negara Pulau Pinang (Penang National Park), Malaysia was studied to assess the impact of various anthropogenic activities, such as fishing, ecotourism and floating cage culture. Samples were obtained at 200 m intervals within the subtidal zone, extending up to 1200 m offshore at Teluk Bahang, Teluk Aling, Teluk Ketapang and Pantai Acheh. The depth within coastal waters ranged between 1.5 m and 10.0 m, with predominantly muddy substrate at most stations. Water quality analysis showed little variation in micronutrient (nitrite, NO2; nitrate, NO3; ammonia, NH4 and orthophosphate, PO4) concentrations between sampling stations. Temperature (29.6±0.48°C), salinity (29.4±0.28 ppt), dissolved oxygen content (5.4±0.95 mg/l) and pH (8.5± 0.13) also showed little fluctuation between stations. A total of nine genera of foraminifera were identified in the study (i.e., Ammonia, Elphidium, Ammobaculites, Bigenerina, Quinqueloculina, Reopax, Globigerina, Textularia and Nonion). The distribution of benthic foraminifera was dominated by opportunistic groups that have a high tolerance to anthropogenic stressors. Ammonia had the highest frequency of occurrence (84.7%), followed by Bigenerina (50%), Ammobaculites (44.2%) and Elphidium (38.9%). The Ammonia-Elphidium Index (AEI) was used to describe the hypoxic condition of benthic communities at all sites. Teluk Bahang had the highest AEI value. The foraminiferal assemblages and distribution in Teluk Bahang, Teluk Aling, Teluk Ketapang and Pantai Acheh showed no correlation with physical or chemical environmental parameters. PMID:24575240

  14. Photosynthesis and respiration of some marine benthic algae from Spitsbergen

    OpenAIRE

    Latala, Adam

    1990-01-01

    Light-photosynthesis curves for 9 species of benthic algae from the Hornsund fiord were determined. As a result of adaptation to the conditions in the Arctic, benthic algae from Spitsbergen have a low requirement of light. Saturation and compensation points are low and within a range typical for shadow-tolerant plants.The values for gas exchange rates indicate that Arctic algae have lower photosynthctic capacity than temperate species.

  15. Exploring Benthic Biodiversity Patterns and Hotspots on European Margin Slopes

    OpenAIRE

    Roberto Danovaro; Miquel Canals; Serge Heussner; Nikolaos Lampadariou; Ann Vanreusel

    2009-01-01

    There is increasing evidence that continental slope ecosystems represent one of the major repositories of benthic marine biodiversity. The enhanced levels of biodiversity along slopes are hypothesized to be a source of biodiversity for continental shelves and deeper basins. Continental margins are increasingly altered by human activities, but the consequences of these anthropogenic impacts on benthic biodiversity and ecosystem functioning are almost completely unknown. Thus, there is an urgen...

  16. Exploring benthic biodiversity patterns and hotspots on European margin slopes

    OpenAIRE

    Danovaro, R.; M. Canals; Gambi, C.; S. Heussner; Lampadariou, N.; Vanreusel, A.

    2009-01-01

    There is increasing evidence that continental slope ecosystems represent one of the major repositories of benthic marine biodiversity. The enhanced levels of biodiversity along slopes are hypothesized to be a source of biodiversity for continental shelves and deeper basins. Continental margins are increasingly altered by human activities, but the consequences of these anthropogenic impacts on benthic biodiversity and ecosystem functioning are almost completely unknown. Thus, there is an urgen...

  17. Recruitment and Succession in a Tropical Benthic Community in Response to In-Situ Ocean Acidification.

    Directory of Open Access Journals (Sweden)

    Elizabeth Derse Crook

    Full Text Available Ocean acidification is a pervasive threat to coral reef ecosystems, and our understanding of the ecological processes driving patterns in tropical benthic community development in conditions of acidification is limited. We deployed limestone recruitment tiles in low aragonite saturation (Ωarag waters during an in-situ field experiment at Puerto Morelos, Mexico, and compared them to tiles placed in control zones over a 14-month investigation. The early stages of succession showed relatively little difference in coverage of calcifying organisms between the low Ωarag and control zones. However, after 14 months of development, tiles from the low Ωarag zones had up to 70% less cover of calcifying organisms coincident with 42% more fleshy algae than the controls. The percent cover of biofilm and turf algae was also significantly greater in the low Ωarag zones, while the number of key grazing taxa remained constant. We hypothesize that fleshy algae have a competitive edge over the primary calcified space holders, coralline algae, and that acidification leads to altered competitive dynamics between various taxa. We suggest that as acidification impacts reefs in the future, there will be a shift in community assemblages away from upright and crustose coralline algae toward more fleshy algae and turf, established in the early stages of succession.

  18. Lista preliminar das espécies da macrofauna de fundos inconsolidados da Baía de Guaratuba, Paraná, Brasil Preliminary list of softbotom benthic macrofauna from Guaratuba Bay, Paraná, Brazil

    OpenAIRE

    Arno Blankensteyn; Ronny Scheffler de Moura

    2002-01-01

    A qualitative survey of benthic macrofauna was carried out in the Guaratuba Bay, Paraná,Brazil. Twenty nine stations were sampled from April to July, 1996, including sublitoral and intertidal zones resulting in a preliminary list with 69 taxa. From this total, only 31,9% (22 taxa) were previously registered to the area.

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

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

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

    2016-04-01

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

  1. Progress research report, 27 June, 1983, benthic invertebrate studies

    International Nuclear Information System (INIS)

    The benthic ecological research at site W-N for the Low Level Waste Ocean Disposal Program is oriented towards characterizing the invertebrate community associated with the seafloor and towards understanding the links within the benthic food web. Stomach analyses of benthic-feeding fishes reveal a varied diet of benthic and peloagio-benthic forms. From the trawl samples of megafauna, the basic community structure is similar to other deep-sea areas with echinoderms as the predominant forms. For the macrofauna, polychaete worms comprise the dominant taxonomic group. Very little is known about the fauna at area W-N on the species level. Such data will help answer the question of whether this community is characteristic of the continental slope base or is a transition between continentally-influenced communities and those in the central portion of ocean basins. Environmental differences within the area suggest that the benthic fauna should also vary in composition and abundance. 19 references, 7 figures, 5 tables

  2. Photobiology of the deep twilight zone and beyond

    Science.gov (United States)

    Waterman, Talbot H.

    1997-02-01

    Photobiology in the twilight zone of the deep sea depends on faint light of two, or possibly three, origins: sunlight, bioluminescence and some visible radiation near the bottom associated with hydrothermal vents. The deep twilight zone also contains two quite distinct ecosystems: the vast open ocean pelagic regime far from the shore and the bottom as well as the far less expansive benthic regime with quite different characteristic animals that live on, in or near the sea bo10 Most of the whole ocean's benthic regime with a mean depth over 3000m is well below the twilight zone, which eliminates sunlight as a light source there. Many of the most familiar deepsea animals with their spectacular arrays of dennal light organs and remarkable eyes are from the pelagic 19, 25 The less familiar benthic fishes and crustaceans sometimes have curious internal light organs powered by bacteria13 and occasional incredibly modified eyes.30 With the exception of those on the fishing rods of most female deepsea anglerfish, where the light is produced by symbiotic bacteria, all the numerous light organs of pelagic deepsea fishes are generally believed to manage their own chemiluminescence independent of luminous bacteria.17

  3. Sensitivity of Coastal Environments and Wildlife to Spilled Oil: Upper Coast of Texas: BENTHIC (Benthic habitat polygons)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This data set contains known locations of patchy and continuous seagrass and oyster reef habitat for the Upper Coast of Texas benthic habitat data. This data set...

  4. mkk_benthic_habitats - Benthic habitat of the coral reef ecosystem on the south shore of Molokai Hawaii.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A benthic habitat polygon coverage has been created of the coral reef ecosystem on the south shore of Moloka'i. Polygons were hand-digitized from visual...

  5. Environmental effects of oil and gas exploration on the benthic fauna of the Norwegian Continental Shelf : An analysis using the OLF-database

    OpenAIRE

    2009-01-01

    The main objective of these studies was to utilize the large amount of co-occurring fauna and chemical data collected in different contamination zones around offshore installations to derive ecologically relevant protection levels for marine benthic communities on the Norwegian Continental Shelf (NCS). The data used are collected in regular monitoring surveys in the vicinity of oil- and gas installations at the NCS and stored in the OLF-database (OLF = The Norwegian Oil Industry Association)....

  6. Community shelter use in response to two benthic decapod predators in the Long Island Sound.

    Science.gov (United States)

    Hudson, David M; Reagan, Dugan; Crivello, Joseph F

    2016-01-01

    To investigate community shelter effects of two invasive decapod species, Hemigrapsus sanguineus and Carcinus maenas, in the Long Island Sound (LIS), we deployed artificial shelters in the intertidal and immediate subtidal zones. These consisted of five groups during the summer: a control, a resident H. sanguineus male or female group, and a resident C. maenas male or female group. We quantified utilization of the shelters at 24 h by counting crabs and fish present. We found significant avoidance of H. sanguineus in the field by benthic hermit crabs (Pagurus spp.) and significant avoidance of C. maenas by the seaboard goby (Gobiosoma ginsburgi). The grubby (Myoxocephalus aenaeus) avoided neither treatment, probably since it tends to be a predator of invertebrates. H. sanguineus avoided C. maenas treatments, whereas C. maenas did not avoid any treatment. Seasonal deployments in the subtidal indicated cohabitation of a number of benthic species in the LIS, with peak shelter use corresponding with increased predation and likely reproductive activity in spring and summer for green crabs (C. maenas), hermit crabs (Pagurus spp.), seaboard gobies (G. ginsburgi), and grubbies (Myoxocephalus aenaeus). PMID:27547570

  7. Geological sampling data and benthic biota classification: Buzzards Bay and Vineyard Sound, Massachusetts

    Science.gov (United States)

    Ackerman, Seth D.; Pappal, Adrienne L.; Huntley, Emily C.; Blackwood, Dann S.; Schwab, William C.

    2015-01-01

    Sea-floor sample collection is an important component of a statewide cooperative mapping effort between the U.S. Geological Survey (USGS) and the Massachusetts Office of Coastal Zone Management (CZM). Sediment grab samples, bottom photographs, and video transects were collected within Vineyard Sound and Buzzards Bay in 2010 aboard the research vesselConnecticut. This report contains sample data and related information, including analyses of surficial-sediment grab samples, locations and images of sea-floor photography, survey lines along which sea-floor video was collected, and a classification of benthic biota observed in sea-floor photographs and based on the Coastal and Marine Ecological Classification Standard (CMECS). These sample data and analyses information are used to verify interpretations of geophysical data and are an essential part of geologic maps of the sea floor. These data also provide a valuable inventory of benthic habitat and resources. Geographic information system (GIS) data, maps, and interpretations, produced through the USGS and CZM mapping cooperative, are intended to aid efforts to manage coastal and marine resources and to provide baseline information for research focused on coastal evolution and environmental change.

  8. Effects of hypoxia caused by mussel farming on benthic foraminifera in semi-closed Gamak Bay, South Korea.

    Science.gov (United States)

    Lee, Yeon Gyu; Jeong, Da Un; Lee, Jung Sick; Choi, Yang Ho; Lee, Moon Ok

    2016-08-15

    Seawater monitoring and geochemical and benthic foraminiferal analysis of sediments were conducted to identify the effects of hypoxia created by a mussel farm on benthic foraminifera in a semi-closed bay. Extremely polluted reductive conditions with a high content of organic matter (OM) at >12.0% and oxygen minimum zones (OMZs) with dissolved oxygen (DO) <0.4mg∙L(-1) were formed below the mussel farm in the northwest area of Gamak Bay, and gradually diffused toward the south. Highly similar patterns of variation were observed in species diversity, abundance frequency, and benthic foraminiferal assemblage distributed from Elphidium subarcticum-Ammonia beccarii in the northwest area through E. subarcticum-A. beccarii-Trochammina hadai, E. subarcticum-A. beccarii-Elphidiumclavatum, and E. clavatum-Ammonia ketienziensis in the southern area. These phenomena were caused by hydrodynamics in the current water mass. It was thought that E. subarcticum is a bioindicator of organic pollution caused by the mussel farm. PMID:27267115

  9. Benthic foraminifera and trace element distribution: a case-study from the heavily polluted lagoon of Venice (Italy).

    Science.gov (United States)

    Coccioni, Rodolfo; Frontalini, Fabrizio; Marsili, Andrea; Mana, Davide

    2009-01-01

    Living benthic foraminiferal assemblages were studied in surface samples collected from the lagoon of Venice (Italy) in order to investigate the relationship between these sensitive microorganisms and trace element pollution. Geochemical analysis of sediments shows that the lagoon is affected by trace element pollution (Cd, Cu, Ni, Pb, Zn and Hg) with the highest concentrations in its inner part, which corresponds to the Porto Marghera industrial area. The biocenosis are largely dominated by Ammonia tepida, Haynesina germanica and Cribroelphidium oceanensis and, subordinately, by Aubignyna perlucida, Ammonia parkinsoniana and Bolivina striatula. Biotic and abiotic factors were statistically analyzed with multivariate technique of cluster analysis and principal component analysis. The statistical analysis reveals a strong relationship between trace elements (in particular Mn, Pb and Hg) and the occurrence of abnormalities in foraminiferal tests. Remarkably, greater proportions of abnormal specimens are usually found at stations located close to the heaviest polluted industrial zone of Porto Marghera. This paper shows that benthic foraminifera can be used as useful and relatively speedy and inexpensive bio-indicators in monitoring the health quality of the lagoon of Venice. It also provides a basis for future investigations aimed at unraveling the benthic foraminiferal response to human-induced pollution in marine and transitional marine environments. PMID:19733368

  10. Seasonal changes in interstitial salinities and seasonal movements of subtidal benthic invertebrates in the Fraser River estuary, B.C.

    Science.gov (United States)

    Chapman, Peter M.; Brinkhurst, Ralph O.

    1981-01-01

    The subtidal benthic fauna of the lower Fraser River, a salt-wedge estuary, was sampled monthly from June 1977 to August 1978 in mud substrates at six stations ranging from oligohaline to polyhaline. Subtidal interstitial salinities were also measured and were related to the seasonal distribution of the estuarine benthic fauna. Interstitial salinities of silty sediments do not vary diurnally, but the transition zone between salt and fresh interstitial water is cyclically shifted up- and downstream in relation to freshwater discharge, leading to seasonal shifts in the distribution of benthic infaunal species. Seasonal shifts are shown to occur in the oligochaetes Limnodrilus hoffmeisteri, Tubifex tubifex, Tubificoides gabriellae, Paranais litoralis, Specaria fraseri, Nais communis and Nais elinguis, and of the polychaetes Eteone longa, Amphicteis sp. and Polydora kempi japonica. These species comprised over 25% of the total taxa collected and over 60% of the individuals collected. The data on other species distributions do not conflict with the hypothesis of cyclic changes related to seasonal interstitial salinities. The changes vary in extent in relation to runoff, and appear to be a feature of salt-wedge estuaries in general.

  11. Benthic algal vegetation in Isfjorden, Svalbard

    Directory of Open Access Journals (Sweden)

    Stein Fredriksen

    2015-08-01

    Full Text Available Benthic algal vegetation was investigated at 10 sites in Isfjorden, Svalbard. Five sites were visited during summer 2010 and five during summer 2012. Both the littoral and sublittoral vegetation were sampled, the littoral by hand-picking and use of a throwable rake and the sublittoral using a triangular dredge. A total of 88 different taxa were registered, comprising 17 Chlorophyta, 40 Ochrophyta, 30 Rhodophyta and the Xantophyceae Vaucheria sp. The green algae Ulvaria splendens (Ruprecht Vinogradova was recorded in Svalbard for the first time. Most of the sites consisted of hard bottom substrate, but one site, Kapp Wijk, consisted of loose-lying calcareous red algae (rhodoliths and had species not recorded elsewhere. The sublittoral at the other sites was dominated by kelp. Molecular analysis confirmed the presence of the red alga Ceramium virgatum and a dwarf form of the brown alga Fucus vesiculosus. This study provides a baseline for future studies investigating changes in the vegetation due to environmental changes.

  12. Coastal zone

    International Nuclear Information System (INIS)

    The report entitled Climate Change Impacts and Adaptation : A Canadian Perspective, presents a summary of research regarding the impacts of climate change on key sectors over the past five years as it relates to Canada. This chapter on the coastal zone focuses on the impact of climate change on Canada's marine and Great Lakes coasts with tips on how to deal with the impacts associated with climate change in sensitive environments. This report is aimed at the sectors that will be most affected by adaptation decisions in the coastal zone, including fisheries, tourism, transportation and water resources. The impact of climate change in the coastal zone may include changes in water levels, wave patterns, storm surges, and thickness of seasonal ice cover. The Intergovernmental Panel on Climate Change projects global average sea level will rise between 9 and 88 centimetres between 1990 to 2100, but not all areas of Canada will experience the same rate of future sea level change. The main physical impact would be shoreline change that could result in a range of biophysical and socio-economic impacts, some beneficial, some negative. The report focuses on issues related to infrastructure and communities in coastal regions. It is noted that appropriate human adaptation will play a vital role in reducing the extent of potential impacts by decreasing the vulnerability of average zone to climate change. The 3 main trends in coastal adaptation include: (1) increase in soft protection, retreat and accommodation, (2) reliance on technology such as geographic information systems to manage information, and (3) awareness of the need for coastal adaptation that is appropriate for local conditions. 61 refs., 7 figs

  13. Determining productivity of transferred benthic biofilms within wetlands differing in anthropogenic stressors

    International Nuclear Information System (INIS)

    Algal biofilms are a fundamental contributor to wetland productivity. The films maintain high turnover rates, nutrient uptake and storage capacities are prevalent in shallow water as well as over large littoral zones. This study investigated biofilm transfer techniques as a means of accelerating carbon capture, plant production, and colonization in reclaimed oil sand wetlands affected by process water. The study examined the productivity of transferred biofilms and their ability to accelerate succession; methods of transferring biofilms; and the community composition of algae in relation to other substrates. Microcosms with 4 types of substrates were submersed in experimental trenches containing either process water or natural water. Dissolved oxygen, chlorophyll, and biomass standing crop sampling was conducted at intervals throughout a 1-year period. Analysis of variance (ANOVA) was conducted to compare the substrate types. Results of the study will be used to assess the impacts of oil sands process affected materials (OSPM) on benthic biofilm productivity and the initial carbon accumulation process.

  14. Spatial analyses of benthic habitats to define coral reef ecosystem regions and potential biogeographic boundaries along a latitudinal gradient.

    Directory of Open Access Journals (Sweden)

    Brian K Walker

    Full Text Available Marine organism diversity typically attenuates latitudinally from tropical to colder climate regimes. Since the distribution of many marine species relates to certain habitats and depth regimes, mapping data provide valuable information in the absence of detailed ecological data that can be used to identify and spatially quantify smaller scale (10 s km coral reef ecosystem regions and potential physical biogeographic barriers. This study focused on the southeast Florida coast due to a recognized, but understudied, tropical to subtropical biogeographic gradient. GIS spatial analyses were conducted on recent, accurate, shallow-water (0-30 m benthic habitat maps to identify and quantify specific regions along the coast that were statistically distinct in the number and amount of major benthic habitat types. Habitat type and width were measured for 209 evenly-spaced cross-shelf transects. Evaluation of groupings from a cluster analysis at 75% similarity yielded five distinct regions. The number of benthic habitats and their area, width, distance from shore, distance from each other, and LIDAR depths were calculated in GIS and examined to determine regional statistical differences. The number of benthic habitats decreased with increasing latitude from 9 in the south to 4 in the north and many of the habitat metrics statistically differed between regions. Three potential biogeographic barriers were found at the Boca, Hillsboro, and Biscayne boundaries, where specific shallow-water habitats were absent further north; Middle Reef, Inner Reef, and oceanic seagrass beds respectively. The Bahamas Fault Zone boundary was also noted where changes in coastal morphologies occurred that could relate to subtle ecological changes. The analyses defined regions on a smaller scale more appropriate to regional management decisions, hence strengthening marine conservation planning with an objective, scientific foundation for decision making. They provide a framework

  15. Benthic bioindicators from the lakes of Northern Yakutia (Siberia, Russia) in paleoclimatic research

    Science.gov (United States)

    Tumanov, O. N.; Nazarova, L. B.; Frolova, L. A.; Pestryakova, L. A.

    2012-04-01

    High latitude regions are particularly affected by global climate change. Aquatic ecosystems are known to respond quickly and sensitively to such changes (Carpenter et al., 1992; Findlay et al. 2001; Smol et al., 2005). This effect is especially dramatic in regions with continental climates such as Northern and Eastern Siberia. In 2008, Russian-German expedition investigated 33 lakes of Kolyma river basin, North-Eastern Yakutia. The region of investigation is located in the mouth of Kolyma river between approximately 68°2' and 69°4' N and between 159°8' and 161°9' E. It's a most north-eastern region of Yakutia, so it's suitable for paleolimnological investigations. The investigated lakes are situated along the 200 km transect crossing 3 vegetation zones: polygonal tundra, forest tundra and northern taiga. The main aims were establishing a calibration dataset for paleoenvironmental reconstructions by using aquatic organisms, investigation of limnological variables and the influence of the environmental conditions on distribution of aquatic organisms in Yakutian lakes. The modern benthic fauna of the lakes is represented by 89 taxa from 14 taxonomic groups. The most abundant group was Mollusca. The most taxonomically diverse group was Chironomidae. A unique for this region species were discovered, such as Cincinna kamchatica, Physa jarochnovitschae, Colymbetes dolabratus, Ilybius wasastjernae, Xestochironomus sp., Agrypnia sp. etc. Cluster analysis of taxonomical composition of the benthic fauna of these lakes showed high dependency to vegetation zones. The highest levels of hydrobiological indexes (Shannon, Evenness, species richness) were registered in forest tundra. CCA analysis showed that the most influential factors in species distribution were climate-dependant factors, such as mean Tair of July, pH and water depth. Data from taxonomical analysis of Chironomidae group were used for establishing a calibration dataset for paleoenvironmental reconstructions.

  16. Relationships between benthic cover, current strength, herbivory, and a fisheries closure in Glovers Reef Atoll, Belize

    Science.gov (United States)

    McClanahan, T.; Karnauskas, M.

    2011-03-01

    Benthic cover, current strengths, and fish abundance and diversity were examined on 150 lagoonal patch reefs and mapped to determine their distribution, inter-relationships, and relationship to the fisheries closure in Glovers Reef Atoll. Current strength was highest at both the northern and southern ends of the atoll and largely controlled by local wind and weakly by tidal forcing. Benthic functional group distributions varied throughout the atoll and had distinct areas of dominance. In contrast, dominance of coral species was weaker, reflecting the lost cover and zonation of Acropora, Porites, and Montastraea that were reported in the 1970s. Hard and soft corals dominated the windward rim, while the central and leeward lagoon had lower current strengths and sea grass and fleshy green algae were relatively more abundant. Brown erect algae were relatively more common in the north and calcifying green and red algae the southern ends of the atoll. Only Montastraea- Agaricia agaricites distributions were similar to reports from the 1970s with high relative dominance in the southern and northeast atoll. The central-northern zone, which was described as an Acropora zone in the 1970s, was not recognizable, and Porites porites, P. astreoides, Millepora alcicornis, and Favia fragum were the most abundant species during this survey . Hard and soft coral cover abundance declined away from the reef rim and tidal channels and was associated with fast seawater turnover and high surgeonfish abundance. Consequently, the windward rim area has retained the most original and persistent hard-soft coral and surgeonfish community and is considered a priority for future management, if the goal is to protect coral from fishing impacts.

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

    Science.gov (United States)

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

    2016-01-01

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

  18. Naturally Ocurring Polyphosphate-accumulating Bacteria in Benthic Biofilms

    Science.gov (United States)

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

    2014-12-01

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

  19. [Diversity, abundance and distribution of benthic macrofauna on rocky shores from North Sucre State, Venezuela].

    Science.gov (United States)

    Fernandez, Johanna; Jiménez, Mayré; Allen, Thays

    2014-09-01

    The rocky intertidal zone is among the most extreme physical environments on Earth. Organisms living in this area are constantly stricken by physico-chemical and biological factors. Due to the ecological importance of these areas, we studied the diversity, abundance and distribution of the rocky coastline benthic macrofauna, from the North coast of Sucre State, Venezuela. We performed bimonthly samplings from November 2008 to September 2009. The collection of biological material in the littoral zone (supra, mid and infralittoral) was done manually with a grid of 0.25m2. Organisms were preserved in 10% formalin for later identification and analysis (ecological parameters and Kruskal-Wallis test to the abundance and diversity). We found a total 19,020 organisms (86 spp.), in 8 phyla, 45 families and 47 genera. Mollusks were the most abundant and diverse (58 spp.), followed by arthropods (12 spp.), annelids (7 spp.), echinoderms (5 spp.), and the less represented cnidarians, sipunculids, nemertinids and urochordates (1 sp.). The zonation found coincided with the universal scheme of zonation. The towns of Rio Boca and Rio Caribe presented the highest values of ecological parameters, and the lowest were found in Playa Grande. Statistical significant differences were found in the abundance and diversity of macrofauna among the three zones. The little information on the composition and distribution of macrobenthic rocky coastline, prevents a better comparison, however the results contribute to the knowledge of the marine biodiversity in this region. PMID:25412527

  20. SHE analysis for biozonation of benthic foraminiferal assemblages from western arctic ocean

    Science.gov (United States)

    Osterman, L.E.; Buzas, M.A.; Hayek, L.-A.C.

    2002-01-01

    Benthic foraminiferal species abundance in samples from three Mendeleyev Ridge box cores were analyzed by cluster analysis and the newer method of SHE analysis. Previously, the latter technique only has been used on foraminiferal data from depth transects of modern surface sediment samples. Unlike most methods, which initially compare all possible pairs of samples, the SHE procedure results in a linear pattern if a sequence of samples are from the same statistical distribution. A change in slope indicates a statistical change in community structure and / or a change in species composition. The research reported herein is the first application of SHE for the purpose of identifying biozones in sediment core samples for the purpose of stratigraphic correlation. Both cluster analysis and the SHE method provided zonation within cores. However, the cluster method often produced clusters that were difficult to identify and also contained a mixture of samples without stratigraphic continuity. In contrast, SHE resulted in easily identifiable biozones and ensured temporal continuity within them. In general, the cluster analysis produced more zones than the SHE analysis. About 87% of the cluster zones and 64% of the SHE zones were correlated across more than one core. The average age range for correlated biozone boundaries among the three cores, based on radiocarbon dates, was 821 years using cluster analysis and 296 years using SHE. The sequential nature of the analysis, ease in choosing boundaries, and correlation of these boundaries across cores makes SHE the preferred technique.

  1. Quo vadis NW Black Sea benthic ecosystems?

    Science.gov (United States)

    Traian Gomoiu, Marian

    2016-04-01

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

  2. Sea Carousel—A benthic, annular flume

    Science.gov (United States)

    Amos, Carl L.; Grant, J.; Daborn, G. R.; Black, K.

    1992-06-01

    A benthic annular flume (Sea Carousel) has been developed and tested to measure in situ the erodibility of cohesive sediments. The flume is equipped with three optical backscatter sensors, a lid rotation switch, and an electromagnetic (EM) flow meter capable of detecting azimuthal and vertical components of flow. Data are logged at rates up to 10·66 Hz. Erodibility is inferred from the rate of change in suspended sediment concentration detected in the annulus. The energy-density/wave number spectrum of azimuthal flow showed peaks in the energy spectrum at paddle rotation wave numbers (k) of 14 and 7 m -1 (macroturbulent time scales) but were not significant. Friction velocity ( U*), measured (1) at 1 Hz using a flush-mounted hot-film sensor, and (2) derived from measured velocity profiles in the inner part of the logarithmic layer gave comparable results for Ū* 0·32 m s -1. Radial velocity gradients were proportional to ( Ū y - 0·32 m s -1). Maximum radial differences in U* were 10% for Ū y = 0·5 ms -1. Suspended sediment mass concentration ( S) in the annulus resulted in a significant decrease (10·5%) in Ū* derived by method (1) over the range 0calibration with changes in S. Subaerial deployments of Sea Carousel caused severe substrate disturbance, water losses, and aeration of the annulus. Submarine deployments produced stable results, though dispersion of turbid flume water took place. Results clearly demonstrated the existence of 'Type I' and 'Type II' erosion documented from laboratory studies.

  3. The intriguing relationship between coiling direction and reproductive mode in benthic foraminifera

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Rao, A

    direction changes. The relationship between mode of reproduction and coiling directions in benthic foraminifera is explored. Benthic foraminiferal species Cavarotalia annectens (Paarker & Jones) in 58 samples obtained from a core off Karwar, west coast...

  4. Immediate response of meio and macrobenthos to disturbance caused by a benthic disturber

    Digital Repository Service at National Institute of Oceanography (India)

    Ingole, B.S.; Ansari, Z.A.; Matondkar, S.G.P.; Rodrigues, N.

    The probable impact of nodule mining on benthic biota was studied by creating a benthic disturbance. During the predisturbance study in the Central Indian Basin, box core samples were analyzed for the distribution, composition and abundance...

  5. Benthic foraminifera as proxy for oxygen-depleted conditions off the central west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Mazumder, A.; Henriques, P.J.; Saraswat, R.

    In order to study the response of benthic foraminifera, especially the rectilinear bi- and tri-serial benthic foraminifera (RBF) to oxygen-depleted conditions from the Arabian Sea off central west coast of India, 103 surface sediment samples...

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

    Science.gov (United States)

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

  7. Linkages between reef fish demographics and benthic habitat characteristics in Tutuila, American Samoa

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic habitats play vital roles in the distribution and abundances of marine resources. Understanding how fish populations respond to variability of benthic...

  8. Niche separation by littoral-benthic Chydoridae (Cladocera, Crustacea in a deep lake - potential drivers of their distribution and role in littoral-pelagic coupling

    Directory of Open Access Journals (Sweden)

    Malgorzata Adamczuk

    2014-05-01

    Full Text Available Niche separation of 22 species of benthic Chydoridae was examined in a depth gradient in the littoral zone of a deep Lake Piaseczno (eastern Poland, by using a trap sampler. Individual species showed high segregation across the littoral zone according to depth, macrophyte biomass, total organic carbon (TOC, conductivity and pH, of which the depth turned out to be the most important. The species Acroperus harpae, Alona affinis, Alonella nana, Leydigia acanthocercoides, Pseudochydorus globosus, Pleuroxus trigonellus and Pleuroxus aduncus were found in the whole littoral zone, but the remaining Chydoridae species displayed clear spatial distribution, e.g. Coronatella rectangula, Acroperus elongatus, Alona guttata, Alonella excisa, Alonella exigua, Rhychotalona falcata, Monospilus dispar and Pleuroxus truncatus settled the shallower parts of the littoral, whereas Eurycercus lamellatus, Camptocercus rectirostris, Pleuroxus laevis, Graptoleberis testudinaria, Alona costata, Pleuroxus uncinatus and Alona intermedia were found mainly in areas located 3-6 m deep. To find out the role of Chydoridae in littoral-pelagic food web coupling, the contribution of chydorids to total number of Cladocera in the guts of fish was estimated showing that they are an important intervening link in nutrient movement from the littoral to the pelagic zone, as their contribution to the total cladoceran number found in guts of fish caught in the pelagic zone was even as high as 98%. This study provides more insight into the nature of constraints associated with littoral-benthic cladocerans’ habitat preferences and their importance in littoral-pelagic coupling.

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

    Science.gov (United States)

    Corcoran, Patricia L

    2015-08-01

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

  10. Quantifying tidally driven benthic oxygen exchange across permeable sediments

    DEFF Research Database (Denmark)

    McGinnis, Daniel F.; Sommer, Stefan; Lorke, Andreas;

    2014-01-01

    of permeable sediments and has been identified as increasingly at risk for developing hypoxia. Therefore, we investigate the benthic O-2 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 high O-2 flux variability results from deeper sediment O-2 penetration depths and increased O-2 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......Continental shelves are predominately (approximate to 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...

  11. Changes in carbon sources fueling benthic secondary production over depth and time: coupling Chironomidae stable carbon isotopes to larval abundance.

    Science.gov (United States)

    Frossard, Victor; Verneaux, Valérie; Millet, Laurent; Magny, Michel; Perga, Marie-Elodie

    2015-06-01

    Stable C isotope ratio (δ(13)C) values of chironomid remains (head capsules; HC) were used to infer changes in benthic C sources over the last 150 years for two French sub-Alpine lakes. The HCs were retrieved from a series of sediment cores from different depths. The HC δ(13)C values started to decrease with the onset of eutrophication. The HC δ(13)C temporal patterns varied among depths, which revealed spatial differences in the contribution of methanotrophic bacteria to the benthic secondary production. The estimates of the methane (CH4)-derived C contribution to chironomid biomass ranged from a few percent prior to the 1930s to up to 30 % in recent times. The chironomid fluxes increased concomitantly with changes in HC δ(13)C values before a drastic decrease due to the development of hypoxic conditions. The hypoxia reinforced the implication for CH4-derived C transfer to chironomid production. In Lake Annecy, the HC δ(13)C values were negatively correlated to total organic C (TOC) content in the sediment (Corg), whereas no relationship was found in Lake Bourget. In Lake Bourget, chironomid abundances reached their maximum with TOC contents between 1 and 1.5 % Corg, which could constitute a threshold for change in chironomid abundance and consequently for the integration of CH4-derived C into the lake food webs. Our results indicated that the CH4-derived C contribution to the benthic food webs occurred at different depths in these two large, deep lakes (deep waters and sublittoral zone), and that the trophic transfer of this C was promoted in sublittoral zones where O2 gradients were dynamic. PMID:25630956

  12. 20th century human pressures drive reductions in deepwater oxygen leading to losses of benthic methane-based food webs

    Science.gov (United States)

    Belle, Simon; Millet, Laurent; Verneaux, Valérie; Lami, Andrea; David, Etienne; Murgia, Laurie; Parent, Claire; Musazzi, Simona; Gauthier, Emilie; Bichet, Vincent; Magny, Michel

    2016-04-01

    Freshwater lakes play a key role in the global carbon cycle as sinks (organic carbon sequestration) and sources (greenhouse gas emissions). Understanding the carbon cycle response to environmental changes is becoming a crucial challenge in the context of global warming and the preponderance of human pressures. We reconstructed the long-term (1500 years) evolution of trophic functioning of the benthic food web, based on methanotrophic ancient DNA and chironomid isotope analyses). In addition, human land use is also reconstructed in three different lakes (eastern France, Jura Mountains). Our findings confirm that the benthic food web can be highly dependent on methane-derived carbon (up to 50% of the chironomid biomass) and reveal that the activation of this process can correspond to a natural functioning or be a consequence of anthropic perturbation. The studied lakes also showed a similar temporal evolution over the last century with the disappearance of the profundal aquatic insects (Chironomidae, Diptera), considered as keystone for the whole lake food web (e.g., coupling benthic-pelagic), inducing a potential collapse in the transfer of methane to top consumers. This functional state, also called the dead zone expansion, was caused by the change in human land-use occurring at the beginning of the 20th century. The strong modification of agro-pastoral practices (e.g., fertilization practices, intensive grazing, and sewage effluent) modified the influx of nutrients (by diffuse and/or point-source inputs) and induced a significant increase in the trophic status and organic matter sedimentation to reach unprecedented values. Further studies should be planned to assess dead zone expansion and, according to the regime shift theory, to provide environmental tipping points for sustainable resource management.

  13. Enhanced benthic response to upwelling of the Indonesian Throughflow onto the southern shelf of Timor-Leste, Timor Sea

    Science.gov (United States)

    Alongi, Daniel M.; Brinkman, Richard; Trott, Lindsay A.; Silva, Fernando; Pereira, Francisco; Wagey, Tonny

    2013-03-01

    Benthic microbial metabolism and bacterial diagenetic pathways were measured along the southern shelf of Timor-Leste during an upwelling event in the winter SE monsoon season. Vertical profiles of water properties and bottom water nutrient concentrations, and operational ocean modeling showed subsurface upwelling from the Indonesian Throughflow (ITF) along the southern shelf west of longitude 126°25'E and surface upwelling at the far eastern end of the shelf. Warm surface waters above the halocline had salinities of 33.6 to 33.9 overlying cooler ITF water with salinities of 34.4 to 34.6. Beneath the zone of subsurface upwelling and stratification, sediment chlorophyll a (range: 2.8-4.4 µg g-1) and phaeopigment (range: 4.5-7.0 µg g-1) concentrations were sufficient to fuel very rapid rates of benthic oxygen consumption (range: 89.9-142.3 mmol m-2 day-1) and dissolved inorganic carbon (DIC) release (range: 108.1-148.9 mmol m-2 day-1) across the sediment-water interface, and DIC (range: 94.7-142.5 mmol m-2 day-1) and NH4+ (range: 13.3-19.9 mmol m-2 day-1) production from incubated surface (0-10 cm) sediments. Molar ratios of DIC/NH4+ production were lower (range: 6.6-7.7) in fine-grained sediments under the subsurface upwelling regime than in sandy, possibly scoured sediments under surface upwelling (range: 11.9-21.2) where there was no evidence of benthic enrichment. It is proposed that subsurface upwelling along the widest portions of the shelf stimulates phytoplankton production, leading to deposition of fresh phytodetritus that is rapidly decomposed on the seafloor. These zones of high biological activity may attract and support large populations of pelagic fish and cetaceans that have been caught for centuries along the south coast.

  14. Controlling benthic release of phosphorus in different Baltic Sea scales

    DEFF Research Database (Denmark)

    Pitkänen, Heikki; Bendtsen, Jørgen; Hansen, Jørgen L. S.; Lehtoranta, Jouni; Lännergren, Christer; Ollikainen, Markku; Priha, Maarit; Reinikainen, Marko; Saarijärvi, Erkki; Zandersen, Marianne

    The general aim of the PROPPEN project was to study whether it is possible to counteract near-bottom anoxia and excess benthic nutrient release ("internal loading") in the Baltic Sea by artificial oxygenation in cost-efficient and socio-economically beneficial ways. Two pilot sites were selected...... possibilities to counteract anoxia and benthic release of nutrients in coastal marine conditions in the Baltic Sea. The project undertook monitoring of the pilot tests, modelling of effects at different scales, risk management, cost effectiveness and cost benefit analysis....

  15. Benthic fluxes of dissolved organic nitrogen in the Lower St. Lawrence Estuary and implications for selective organic matter degradation

    Directory of Open Access Journals (Sweden)

    M. Alkhatib

    2013-05-01

    Full Text Available The distribution of dissolved organic nitrogen (DON and carbon (DOC in sediment pore waters was determined at nine locations along the St. Lawrence Estuary and in the Gulf of St. Lawrence. The study area is characterized by gradients in the sedimentary particulate organic matter (POM reactivity, bottom water oxygen concentrations, as well as benthic respiration rates. Based on pore water profiles we estimated the benthic diffusive fluxes of DON and DOC. Our results show that DON fluxed out of the sediments at significant rates (110 to 430 μmol m−2 d−1. DON fluxes were positively correlated with sedimentary POM reactivity and sediment oxygen exposure time (OET, suggesting direct links between POM quality, aerobic remineralization and the release of DON to the water column. DON fluxes were on the order of 30% to 64% of the total benthic inorganic fixed N loss due to denitrification, and often exceeded the diffusive nitrate fluxes into the sediments. Hence they represented a large fraction of the total benthic N exchange. This result is particularly important in light of the fact that DON fluxes are usually not accounted for in estuarine and coastal zone nutrient budgets. The ratio of the DON to nitrate flux increased from 0.6 in the Lower Estuary to 1.5 in the Gulf. In contrast to DON, DOC fluxes did not show any significant spatial variation along the Laurentian Channel (LC between the Estuary and the Gulf (2100 ± 100μmol m−2 d−1, suggesting that production and consumption of labile DOC components proceed at similar rates, irrespective of the overall benthic characteristics and the reactivity of POM. As a consequence, the molar C/N ratio of dissolved organic matter (DOM in pore water and the overlying bottom water varied significantly along the transect, with lowest C/N in the Lower Estuary (5–6 and highest C/N (> 10 in the Gulf. We observed large differences between the C/N of pore water DOM with respect to POM, and the degree of

  16. Bipolar gene flow in deep-sea benthic foraminifera

    DEFF Research Database (Denmark)

    Pawlowski, J.; Fahrni, J.; Lecroq, B.;

    2007-01-01

    -sea foraminiferal species (Epistominella exigua, Cibicides wuellerstorfi and Oridorsalis umbonatus), separated by distances of up to 17 000 km. Our results contrast with the substantial level of cryptic diversity usually revealed by molecular studies, of shallow-water benthic and planktonic marine organisms. The...

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

    Science.gov (United States)

    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...

  18. BENTHIC MACROFAUNA AND HABITAT RELATIONSHIPS IN TILLAMOOK BAY

    Science.gov (United States)

    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...

  19. Effects of eutrophication on contaminant cycling in marine benthic systems

    Energy Technology Data Exchange (ETDEWEB)

    Gunnarsson, Jonas; Granberg, Maria; Rosenberg, Rutger [Goeteborg Univ. (Sweden). Dept. of Marine Ecology; Bjoerk, Mikael; Gilek, Michael [Stockholm Univ. (Sweden). Dept. of Systems Ecology

    2000-08-01

    Effects of inputs of organic matter were studied on bioavailability and cycling of hydrophobic organic contaminants (HOCs) in benthic ecosystems of the Baltic and Kattegat Seas. In laboratory experiments, effects of microalgae additions were studied on the bioaccumulation of HOCs (PCBs and PAHs) by the blue mussel Mytilus edulis, the brittle star Amphiura filiformis, and the polychaete Nereis diversicolor. Contrary to the equilibrium partitioning theory, bioaccumulation was proportional to the concentrations of algae and organic carbon. This was attributed to the high nutritional quality of the algal organic carbon and suggests that feeding rather than equilibrium partitioning governed bioaccumulation in these species. In the field, annual mass fluxes of PCBs in blue mussels and in brittle stars were estimated, as well as contaminant transfer to higher trophic levels. Our results suggest that: i) Eutrophication processes may contribute to increase HOC accumulation in benthic species. ii) Temporal variation in the quantity and quality of organic carbon needs to be considered when assessing contamination of benthic systems. iii) Macrofaunal feeding activities are important for the benthic-pelagic coupling of HOCs. iv) Bioturbation enhances the release of HOCs from sediment to overlying water.

  20. Epi-benthic megafaunal zonation across an oxygen minimum zone at the Indian continental margin

    Digital Repository Service at National Institute of Oceanography (India)

    Hunter, W.R.; Oguri, K.; Kitazato, H.; Ansari, Z.A.; Witte, U.

    (Billett, et al., 2006) making the OMZ a provide a rich foraging ground for scavengers (Yeh and Drazen, 2009). On the Indian margin intact carcasses of both fish and squid where observed, on the sea floor, at the 540m station (H. Kitazato & U. Witte, pers...

  1. Uptake of phytodetritus by benthic foraminifera under oxygen depletion at the Indian margin (Arabian Sea)

    Science.gov (United States)

    Enge, A. J.; Witte, U.; Kucera, M.; Heinz, P.

    2014-04-01

    Benthic foraminifera in sediments on the Indian margin of the Arabian Sea, where the oxygen minimum zone (OMZ) impinges on the continental slope, are exposed to particularly severe levels of oxygen depletion. Food supply for the benthic community is high but delivered in distinct pulses during upwelling and water mixing events associated with summer and winter monsoon periods. In order to investigate the response by benthic foraminifera to such pulsed food delivery under oxygen concentrations of less than 0.1 mL L-1 (4.5 μmol L-1), an in situ isotope labeling experiment (13C, 15N) was performed on the western continental slope of India at 540 m water depth (OMZ core region). The assemblage of living foraminifera (>125 μm) in the uppermost centimeter at this depth is characterized by an unexpectedly high population density of 3982 individuals 10 cm-2 and a strong dominance by few calcareous species. For the experiment, we concentrated on the nine most abundant taxa, which constitute 93% of the entire foraminiferal population at 0-1 cm sediment depth. Increased concentrations of 13C and 15N in the cytoplasm indicate that all investigated taxa took up labeled phytodetritus during the 4 day experimental phase. In total, these nine species had assimilated 113.8 mg C m-2 (17.5% of the total added carbon). Uptake of nitrogen by the three most abundant taxa (Bolivina aff. B. dilatata, Cassidulina sp., Bulimina gibba) was 2.7 mg N m-2 (2% of the total added nitrogen). The response to the offered phytodetritus varied largely among foraminiferal species with Uvigerina schwageri being by far the most important species in short-term processing, whereas the most abundant taxa Bolivina aff. B. dilatata and Cassidulina sp. showed comparably low uptake of the offered food. We suggest the observed species-specific differences are related to species biomass and specific feeding preferences. In summary, the experiment in the OMZ core region shows rapid processing of fresh

  2. Waves affect predator-prey interactions between fish and benthic invertebrates.

    Science.gov (United States)

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

    2011-01-01

    Little is known about the effects of waves on predator-prey interactions in the littoral zones of freshwaters. We conducted a set of mesocosm experiments to study the differential effects of ship- and wind-induced waves on the foraging success of littoral fish on benthic invertebrates. Experiments were conducted in a wave tank with amphipods (Gammarus roeseli) as prey, and age-0 bream (Abramis brama, B0), age-0 and age-1 dace (Leuciscus leuciscus, D0 and D1) as predators. The number of gammarids suspended in the water column was higher in the wave treatments compared to a no-wave control treatment, especially during pulse waves mimicking ship-induced waves in comparison to continuous waves mimicking wind-induced waves. The resulting higher prey accessibility in the water column was differently exploited by the three types of predatory fish. D0 and D1 showed significantly higher foraging success in the pulse wave treatment than in the continuous and control treatments. The foraging success of D0 appears to be achieved more easily, since significantly higher swimming activity and more foraging attempts were recorded only for D1 under the wave treatments. In contrast, B0 consumed significantly fewer gammarids in both wave treatments than in the control. Hence, waves influenced predator-prey interactions differently depending on wave type and fish type. It is expected that regular exposure to ship-induced waves can alter littoral invertebrate and fish assemblages by increasing the predation risk for benthic invertebrates that are suspended in the water column, and by shifting fish community compositions towards species that benefit from waves. PMID:21104276

  3. Benthic Ammonia Oxidizers Differ in Community Structure and Biogeochemical Potential Across a Riverine Delta

    Directory of Open Access Journals (Sweden)

    Julian eDamashek

    2015-01-01

    Full Text Available Nitrogen pollution in coastal zones is a widespread issue, particularly in ecosystems with urban or agricultural watersheds. California’s Sacramento-San Joaquin Delta, at the landward reaches of San Francisco Bay, is highly impacted by both agricultural runoff and sewage effluent, leading to chronically high nutrient loadings. In particular, the massive discharge of ammonium into the Sacramento River has altered this ecosystem by increasing ammonium concentrations and thus changing the stoichiometry of inorganic nitrogen stocks, with potential effects throughout the food web. To date, however, there has been little research examining N biogeochemistry or N-cycling microbial communities in this system. We report the first data on benthic ammonia-oxidizing microbial communities and potential nitrification rates for the Sacramento-San Joaquin Delta, focusing on the functional gene amoA (encoding the α-subunit of ammonia monooxygenase. There were stark regional differences in ammonia-oxidizing communities, with ammonia-oxidizing bacteria (AOB outnumbering ammonia-oxidizing archaea (AOA only in the ammonium-rich Sacramento River. High potential nitrification rates in the Sacramento River suggested these communities may be capable of oxidizing significant amounts of ammonium, compared to the San Joaquin River and the upper reaches of San Francisco Bay. Gene diversity also showed regional patterns, as well as phylogenetically unique ammonia oxidizers in the Sacramento River. The community structure and biogeochemical function of benthic ammonia oxidizers appears related to nutrient loadings. Unraveling the microbial ecology and biogeochemistry of N cycling pathways is a critical step toward understanding how such ecosystems respond to the changing environmental conditions wrought by human development and climate change.

  4. The impact of global warming and anoxia on marine benthic community dynamics: an example from the Toarcian (Early Jurassic.

    Directory of Open Access Journals (Sweden)

    Silvia Danise

    Full Text Available The Pliensbachian-Toarcian (Early Jurassic fossil record is an archive of natural data of benthic community response to global warming and marine long-term hypoxia and anoxia. In the early Toarcian mean temperatures increased by the same order of magnitude as that predicted for the near future; laminated, organic-rich, black shales were deposited in many shallow water epicontinental basins; and a biotic crisis occurred in the marine realm, with the extinction of approximately 5% of families and 26% of genera. High-resolution quantitative abundance data of benthic invertebrates were collected from the Cleveland Basin (North Yorkshire, UK, and analysed with multivariate statistical methods to detect how the fauna responded to environmental changes during the early Toarcian. Twelve biofacies were identified. Their changes through time closely resemble the pattern of faunal degradation and recovery observed in modern habitats affected by anoxia. All four successional stages of community structure recorded in modern studies are recognised in the fossil data (i.e. Stage III: climax; II: transitional; I: pioneer; 0: highly disturbed. Two main faunal turnover events occurred: (i at the onset of anoxia, with the extinction of most benthic species and the survival of a few adapted to thrive in low-oxygen conditions (Stages I to 0 and (ii in the recovery, when newly evolved species colonized the re-oxygenated soft sediments and the path of recovery did not retrace of pattern of ecological degradation (Stages I to II. The ordination of samples coupled with sedimentological and palaeotemperature proxy data indicate that the onset of anoxia and the extinction horizon coincide with both a rise in temperature and sea level. Our study of how faunal associations co-vary with long and short term sea level and temperature changes has implications for predicting the long-term effects of "dead zones" in modern oceans.

  5. Benthic Oxygen Uptake in the Arctic Ocean Margins - A Case Study at the Deep-Sea Observatory HAUSGARTEN (Fram Strait)

    Science.gov (United States)

    Cathalot, Cecile; Rabouille, Christophe; Sauter, Eberhard; Schewe, Ingo; Soltwedel, Thomas

    2015-01-01

    The past decades have seen remarkable changes in the Arctic, a hotspot for climate change. Nevertheless, impacts of such changes on the biogeochemical cycles and Arctic marine ecosystems are still largely unknown. During cruises to the deep-sea observatory HAUSGARTEN in July 2007 and 2008, we investigated the biogeochemical recycling of organic matter in Arctic margin sediments by performing shipboard measurements of oxygen profiles, bacterial activities and biogenic sediment compounds (pigment, protein, organic carbon, and phospholipid contents). Additional in situ oxygen profiles were performed at two sites. This study aims at characterizing benthic mineralization activity along local bathymetric and latitudinal transects. The spatial coverage of this study is unique since it focuses on the transition from shelf to Deep Ocean, and from close to the ice edge to more open waters. Biogeochemical recycling across the continental margin showed a classical bathymetric pattern with overall low fluxes except for the deepest station located in the Molloy Hole (5500 m), a seafloor depression acting as an organic matter depot center. A gradient in benthic mineralization rates arises along the latitudinal transect with clearly higher values at the southern stations (average diffusive oxygen uptake of 0.49 ± 0.18 mmol O2 m-2 d-1) compared to the northern sites (0.22 ± 0.09 mmol O2 m-2 d-1). The benthic mineralization activity at the HAUSGARTEN observatory thus increases southward and appears to reflect the amount of organic matter reaching the seafloor rather than its lability. Although organic matter content and potential bacterial activity clearly follow this gradient, sediment pigments and phospholipids exhibit no increase with latitude whereas satellite images of surface ocean chlorophyll a indicate local seasonal patterns of primary production. Our results suggest that predicted increases in primary production in the Arctic Ocean could induce a larger export of more

  6. Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages.

    Directory of Open Access Journals (Sweden)

    Zarinah Waheed

    Full Text Available The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractinian species richness, and benthic reef assemblages following the Reef Check substrate categories, with emphasis on hard coral cover. Variation in scleractinian diversity was based on the species composition of coral families Fungiidae (n = 39, Agariciidae (n = 30 and Euphylliidae (n = 15. The number of coral species was highest at reefs with a larger depth gradient i.e. at the periphery of the study area and in the deep South Banggi Channel. Average live hard coral cover across the sites was 49%. Only 7% of the examined reefs had > 75% hard coral cover, while the majority of the reef sites were rated fair (51% and good (38%. Sites with low coral cover and high rubble fragments are evidence of blast fishing, although the observed damage appeared old. Depth was a dominant factor in influencing the coral species composition and benthic reef communities in the TMP. Besides filling in the information gaps regarding species richness and benthic cover for reef areas that were previously without any data, the results of this study together with information that is already available on the coral reefs of TMP will be used to make informed decisions on zoning plans for conservation priorities in the proposed park.

  7. Coral Reefs at the Northernmost Tip of Borneo: An Assessment of Scleractinian Species Richness Patterns and Benthic Reef Assemblages

    Science.gov (United States)

    Waheed, Zarinah; van Mil, Harald G. J.; Syed Hussein, Muhammad Ali; Jumin, Robecca; Golam Ahad, Bobita; Hoeksema, Bert W.

    2015-01-01

    The coral reefs at the northernmost tip of Sabah, Borneo will be established under a marine protected area: the Tun Mustapha Park (TMP) by the end of 2015. This area is a passage where the Sulu Sea meets the South China Sea and it is situated at the border of the area of maximum marine biodiversity, the Coral Triangle. The TMP includes fringing and patch reefs established on a relatively shallow sea floor. Surveys were carried out to examine features of the coral reefs in terms of scleractinian species richness, and benthic reef assemblages following the Reef Check substrate categories, with emphasis on hard coral cover. Variation in scleractinian diversity was based on the species composition of coral families Fungiidae (n = 39), Agariciidae (n = 30) and Euphylliidae (n = 15). The number of coral species was highest at reefs with a larger depth gradient i.e. at the periphery of the study area and in the deep South Banggi Channel. Average live hard coral cover across the sites was 49%. Only 7% of the examined reefs had > 75% hard coral cover, while the majority of the reef sites were rated fair (51%) and good (38%). Sites with low coral cover and high rubble fragments are evidence of blast fishing, although the observed damage appeared old. Depth was a dominant factor in influencing the coral species composition and benthic reef communities in the TMP. Besides filling in the information gaps regarding species richness and benthic cover for reef areas that were previously without any data, the results of this study together with information that is already available on the coral reefs of TMP will be used to make informed decisions on zoning plans for conservation priorities in the proposed park. PMID:26719987

  8. The influence of cold season warming on the mercury pool in coastal benthic organisms

    Science.gov (United States)

    Bełdowska, Magdalena; Jędruch, Agnieszka; Zgrundo, Aleksandra; Ziółkowska, Marcelina; Graca, Bożena; Gębka, Karolina

    2016-03-01

    One of the tendencies for climate changes in the southern Baltic region is towards the warming of the cold season (late autumn, winter, early spring), which leads to the disappearance of icing even in the coastal zone and affects the fluxes of chemicals in the surface sediments of the coastal zone. This will lengthen the period in which the deposited chemicals may become remobilized from the sediments into pore and near-bottom water. Studies into the mercury concentration in macrophyto- and macrozoobenthos were conducted at two stations in the coastal zone of the southern Baltic, in the Puck Lagoon, from January 2012 to May 2013. It was estimated that the mean annual Hg pool (mass of Hg in flora or fauna per m-2 of sediments) in macrophytobenthos in a year without icing was higher by 30%, and in macrozoobenthos by 25%, compared to an estimated previous year in which the icing period lasted approximately 90 days (as was usual in the period between 1946 and 1991). Taking into account the combined total mass of flora and fauna, it was estimated that lack of icing on the lagoon increases the mean Hg pool in benthic organisms (macrophyto- and macrozoobenthos) by 30%, which in turn considerably increases the Hg load on the first levels of the trophic chain despite a decrease in Hg emissions. The warming of the cold season has a particular influence in areas where macroalgae species are predominant in the biomass over angiosperms. Of the zoobenthic taxa, Corophiumspp. exhibited a tendency for intense growth and Hg accumulation in late autumn.

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

    Science.gov (United States)

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

    2016-01-01

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

  10. Ural River benthic communities response on the chemical spill

    International Nuclear Information System (INIS)

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

  11. Underwater microscopy for in situ studies of benthic ecosystems

    Science.gov (United States)

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

    2016-07-01

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

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

    Science.gov (United States)

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

    2015-04-01

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

  13. Diversity patterns of benthic macrofauna caused by marine fish farming

    OpenAIRE

    Arnaldo Marín; Carlos Sanz-Lázaro

    2011-01-01

    This paper reviews the patterns observed in the diversity and structure of the macrofauna benthic community under the influence of fish farming. First, we explain the effects of organic enrichment on the sediment and the consequences for the inhabiting communities. We describe the diversity trends in spatial and temporal gradients affected by fish farming and compare them with those described by the Pearson and Rosenberg model. We found that in general terms, the trends of...

  14. Benthic communities of shallow-water reefs of Abrolhos, Brazil

    OpenAIRE

    Roberto Villaça; Fábio B. Pitombo

    1997-01-01

    The benthic communities of fringing and mushroom-shaped shallow-water reefs of the Abrolhos region (southern coast of Bahia) were surveyed. Line transects were used to estimate coral and algal percentage cover. Mussismilia braziliensis is the most conspicuous coral species in the majority of the communities surveyed, but turf algal make up the dominant cover in all but one studied reef. In general, communities on mushroom-shaped reefs have higher diversity and higher coral cover than on fring...

  15. Catalog of marine benthic algae from New Caledonia

    OpenAIRE

    Garrigue, Claire; Tsuda, R.T.

    1988-01-01

    A catalog of the marine benthic algae (#Chlorophyta, Phaeophyta$ and #Rhodophyta$) reported from New Caledonia is presented in two sections : 1. Classification; 2. Check list with references and localities. There are 35 genera, 130 species of green algae; 23 genera, 59 species of brown algae; and 79 genera, 147 species of red algae which represent a rich algal flora for the subtropics. (Résumé d'auteur)

  16. Factors affecting benthic impacts at Scottish fish farms.

    Science.gov (United States)

    Mayor, Daniel J; Zuur, Alain F; Solan, Martin; Paton, Graeme I; Killham, Ken

    2010-03-15

    The factors affecting patterns of benthic [seabed] biology and chemistry around 50 Scottish fish farms were investigated using linear mixed-effects models that account for inherent correlations between observations from the same farm. The abundance of benthic macrofauna and sediment concentrations of organic carbon were both influenced by a significant, albeit weak, interaction between farm size, defined as the maximum weight of fish permitted on site at any one time, and current speed. Above a farm size threshold of between 800 and 1000 t, the magnitude of effects at farms located in areas of elevated current speeds were greater than at equivalent farms located in more quiescent waters. Sediment concentrations of total organic matter were influenced by an interaction between distance and depth, indicating that wind-driven resuspension events may help reduce the accumulation of organic waste at farms located in shallow waters. The analyses presented here demonstrate that the production and subsequent fate of organic waste at fish farms is more complex than is often assumed; in isolation, current speed, water depth, and farr size are not necessarily good predictors of benthic impact. PMID:20178333

  17. Benthic foraminifera as biostratigraphical and paleoecological indicators:An example from Oligo-Miocene deposits in the SW of Zagros basin, Iran

    Institute of Scientific and Technical Information of China (English)

    Asghar Roozpeykar; Iraj Maghfouri Moghaddam

    2016-01-01

    The Asmari Formation is a predominantly carbonate lithostratigraphic unit that outcrops in the Zagros Basin. Micropaleontological studies of the Asmari Formation in the Dehdasht area led to the identifi-cation of 51 species of foraminifera taxa. Among the foraminifera, Nummulites cf. vascus, Operculin sp., Operculina complanata, Eulepidina dilatata, Eulepidina elephantine, Ditrupa sp., Miogypsina sp., Elphidium sp. 14, and Borelis melo curdica are the most important. The Lepidocyclina-Operculina-Ditrupa assemblage zone represents the RupelianeChattian age. The Aquitanian age is also defined by co-occurrence of Miogypsina sp. and Elphidium sp. 14, and finally, the first occurrence of Borelis melo curdica represents the Burdigalian. Based on faunal assemblages, the following paleoenvironmental settings are determined for the deposition of the study section: (1) the deep, offshore settings in the aphotic zone dominated by pelagic and small benthic foraminifera;(2) the low energy, turbid and low light parts of the oligophotic zone characterized by large and flat lepidocyclinids (Eulepidina) and Nummulitidae;(3) the low turbidity, deeper part of the inner ramp dominated by Miogypsinoides, Neorotalia, Lepidocyclina, Operculina and Archias; (4) the shallow, marginal marine environment exposed to salinity fluctuations (short-term salinity fluctuations or fully marine conditions) dominated by small benthic Foraminifera (Ammonia and Elphidium); (5) highly translucent, shallowest part of the inner ramp dominated by representatives of Borelis, Meandropsina and Peneroplis. The biotic assemblages represent warm tropical waters with oligotrophic to slightly mesotrophic conditions.

  18. Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

    Digital Repository Service at National Institute of Oceanography (India)

    Manasa, M.; Saraswat, R.; Nigam, R.

    inorganic carbon analysis is ±0.95%. Total carbon (TC) was measured with a CE NCS 2500 elemental analyzer. Suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from BoB 575 In order to identify the relationship between various... benthic foraminifera (AABF), (d) rounded symmetrical benthic foraminifera (RSBF), (e) agglutinated foraminifera, (f) Nonions, (g) Asterorotalids, (h) organic carbon (Corg), and (i) total inorganic carbon (TIC) in the continental shelf region...

  19. Impacts of unusually high sea ice cover on Antarctic coastal benthic food web structure

    OpenAIRE

    Michel, Loïc; Dubois, Philippe; Eleaume,Marc; Fournier, Jérôme; Gallut, Cyril; Jane, Philip; Lepoint, Gilles

    2016-01-01

    Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice cover decrease, the sea ice cover of East Antarctica unexpectedly tends to increase, possibly in relation with changes in atmospheric circulation. Changes in sea ice cover are likely to influence benthic food web structure through modifications of benthic-pelagic coupling, disruption of benthic...

  20. Influence of benthic macrofauna community shifts on ecosystem functioning in shallow estuaries

    OpenAIRE

    Kristensen, Erik; Delefosse, Matthieu; Quintana, Cintia O.; Flindt, Mogens R.; Valdemarsen, Thomas

    2014-01-01

    We aim at identifying how ecosystem functioning in shallow estuaries is affected by rapid shifts in benthic fauna communities. We use the shallow estuary, Odense Fjord, Denmark, as a case study to test our hypotheses that (1) shifts in benthic fauna composition and species functional traits affect biogeochemical cycling with cascading effects on the ecological functioning, which may (2) modulate primary productivity in the overlying water column with feedbacks to the benthic system. Odense Fj...

  1. MERAMOD - predicting the deposition and benthic impact of aquaculture in the Eastern Mediterranean

    OpenAIRE

    Cromey, C.J.; Thetmeyer, Helmut; Lampadariou, N.; Black, K.D.; Kögeler, J.; Karakassis, I.

    2012-01-01

    A model, composed of coupled particle tracking and benthic response modules, for predicting waste solids flux and benthic impacts of gilthead sea bream (Sparus aurata L.) and sea bass (Dicentrarchus labrax L.) aquaculture, was tested at six sites with different hydrodynamics, bathymetries and biomasses in the Aegean and Ionian Seas, Eastern Mediterranean with observations of sediment trap flux and benthic impact indicators. Seven sediment trap validation studies were conducted that varied in ...

  2. Benthic communities on hard substrates covered by Limnoperna fortunei Dunker (Bivalvia, Mytilidae at an estuarine beach (Río de la Plata, Argentina

    Directory of Open Access Journals (Sweden)

    Fernando G. Spaccesi

    2012-01-01

    Full Text Available The structure and composition of benthic communities on hard substrates covered by the nonindigenous bivalve Limnoperna fortunei Dunker, the golden mussel, were quantified in the middle zone of the Río de la Plata Estuary (Argentina from April 2001 through March 2002. A total of 26 taxa were recorded. L. fortunei and Nematoda were the central and dominant groups, with a prodigious abundance of over 80%. The prevalence of L. fortunei, rather than the environmental variables, regulated the dynamics of the associated invertebrate fauna. The golden mussel alters both the structure and function of benthic native communities on hard substrates, allows a higher surface available for colonization and refuge, and provides food source to deposit-feeding organisms in the form of organic or residual material. The mussel also increases the abundance and diversity of taxa on hard substrata - such as Oligochaeta, Hirudinea, Tardigrada, Chironomidae, Copepoda, Tanaidacea, and Hydrachnidia. Similarities and nonparametric multidimensional-scaling analyses indicated that the benthic composition had a seasonal variation. L. fortunei has an environmental impact, an ability to invade new freshwater ambiences worldwide and ecological characteristic comparable to those of Dreissena polymorpha Pallas (the zebra mussel of North America and Europe.

  3. The distribution of benthic biomass in hadal trenches: a modelling approach to investigate the effect of vertical and lateral organic matter transport to the seafloor

    OpenAIRE

    Ichino, Matteo C.; Clark, Malcolm R.; Drazen, Jeffery C.; Jamieson, Alan; Jones, Daniel O. B.; Martin, Adrian P.; Rowden, Ashley A.; Shank, Timothy M.; Yancey, Paul H.; Ruhl, Henry A.

    2015-01-01

    Most of our knowledge about deep-sea habitats is limited to bathyal (200–3000 m) and abyssal depths (3000–6000 m), while relatively little is known about the hadal zone (6000–11,000 m). The basic paradigm for the distribution of deep seafloor biomass suggests that the reduction in biomass and average body size of benthic animals along depth gradients is mainly related to surface productivity and remineralisation of sinking particulate organic carbon with depth. However, there is evidence that...

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    Mishra, Deepak R.

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

  6. Zone distillation: justification

    International Nuclear Information System (INIS)

    The features of zone distillation (with zone melting of refined material and with pulling of condensate) as a new purification method are shown. The method is based on similarity of equations of distillation and crystallization refining. The analogy between some distillation and condensation methods (particularly between zone distillation and zone re-crystallization) is should up

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

    International Nuclear Information System (INIS)

    Highlights: → Benthic biofilters were deployed under an offshore fish farm and in control locations. → We checked the farm influence on fouling, wild fish and sediment near the biofilters. → Fouling under the cages used fish farm-derived wastes, but at low efficiency. → Wild fish were more abundant in the biofilters located below the cages. → Despite these clear benefits, sediment quality around the biofilters did not improve. - Abstract: 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.

  8. Nitrogen fixation in sediments along a depth transect through the Peruvian oxygen minimum zone

    Science.gov (United States)

    Gier, J.; Sommer, S.; Löscher, C. R.; Dale, A. W.; Schmitz, R. A.; Treude, T.

    2015-09-01

    Benthic nitrogen (N2) fixation and sulfate reduction (SR) were investigated in the Peruvian oxygen minimum zone (OMZ). Sediment samples, retrieved by a multiple corer were taken at six stations (70-1025 m) along a depth transect at 12° S, covering anoxic and hypoxic bottom water conditions. Benthic N2 fixation was detected at all sites, with high rates measured in OMZ mid-waters between the 70 and 253 m and lowest N2 fixation rates below 253 m down to 1025 m water depth. SR rates were decreasing with increasing water depth, with highest rates at the shallow site. Benthic N2 fixation depth profiles largely overlapped with SR depth profiles, suggesting that both processes are coupled. The potential of N2 fixation by SR bacteria was verified by the molecular analysis of nifH genes. Detected nifH sequences clustered with SR bacteria that have been demonstrated to fix N2 in other benthic environments. Depth-integrated rates of N2 fixation and SR showed no direct correlation along the 12° S transect, suggesting that the benthic diazotrophs in the Peruvian OMZ are being controlled by additional various environmental factors. The organic matter availability and the presence of sulfide appear to be major drivers for benthic diazotrophy. It was further found that N2 fixation was not inhibited by high ammonium concentrations. N2 fixation rates in OMZ sediments were similar to rates measured in other organic-rich sediments. Overall, this work improves our knowledge on N sources in marine sediments and contributes to a better understanding of N cycling in OMZ sediments.

  9. Linking benthic biodiversity and environmental conditions at the sea floor combining statistical and mechanistic modeling. Case study on the Black Sea's northwestern shelf.

    Science.gov (United States)

    Drion, Roxanne; Capet, Arthur; Gregoire, Marilaure

    2014-05-01

    The preservation of the health and biodiversity of benthic ecosystems is a crucial priority in order to achieve the Good Environmental Status (GES) of marine waters. The multiple pressures acting on the ocean, and in particular, on the coastal zone may prevent the maintenance of biodiversity either directly (e.g. trawling, dredging) or indirectly by modifying environmental conditions at the sea floor (e.g. eutrophication, pollution, acidification, warming). The management of the GES of the benthos in a changing environment and the definition of management strategies (e.g. nutrient reduction) that would preserve GES require tools able to predict the modifications of environmental conditions and to link these modifications to the status of the benthic system. Coupled biogeochemical-circulation models provide a large amount of information on physical (e.g. currents, salinity, temperature, shear stress) and biochemical conditions (e.g. oxygen, inorganic nutrients, sinking detritus) but cannot provide an information on species richness. We propose to link these aspects by applying canonical ordination techniques (e.g. Redundancy Analysis, CoInertia Analysis) on a large data set on macrobenthos collected on the Black Sea's north-western shelf with in-situ sediment data (e.g. granulometry, carbon and nitrogen content, C/N ratio, CaCO3 content) and bottom conditions (e.g. shear stress, level of oxygen stress, flux of organic matter to the sediments) provided by a three dimensional model. Beyond taxonomic description, the analysis is performed on the functional composition of the macrobenthos: A trait-based approach is used to assess the functional composition of the macrobenthos by associating the considered species to a list of biological, ecological and behavioral traits. This approach allows to appraise how local conditions determine the functional and taxonomical diversity and provides a mean to evaluate the impact of habitat alteration on the ecological role of

  10. Influence of environmental factors on abundance and temporal variation of benthic fauna resources in the eutrophic Tha Chin estuary, Samut Sakhon province, Thailand.

    Science.gov (United States)

    Ritnim, Nittaya; Meksumpun, Charumas

    2011-01-01

    The influence of environmental factors on the abundance and temporal variation of benthic fauna resources was studied in the eutrophic Tha Chin estuary located in Samut Sakhon province. The objectives were to analyze the status of abundance and temporal variation of the benthic fauna and to clarify the impacts from environmental factors (water and sediment quality). Field surveys were conducted monthly from August 2007 to March 2008 at 11 sampling stations in the estuary. Based on freshwater runoff volumes, the high-, medium-, and low-loading periods were categorized to be from August to October 2007, November to December 2007, and January to March 2008, respectively. The benthic fauna resources were composed of 57 species in eight phyla. Annelids were the dominant species (with the maximum density being 19,885 individuals/m2), followed by the mollusks. Both densities decreased during the low-loading period in 2008. Water quality deteriorated during the high-loading period. Land-based wastewater discharges decreased the levels of salinity and dissolved oxygen but dramatically increased various nutrients. Consequently, the sediment quality deteriorated during the medium-loading period. Bottom deposits during this time depicted high accumulation of acid volatile sulfides (more than 0.76 mg/g dry weight). Analyzing the environmental relationships, deposit feeders (for example, Nereis sp. and Prionospio sp.) and a clam (Arcuatula sp.) showed potential as bio-indicators for environmental monitoring. The overall results revealed the importance of changes in the water and sediment qualities that had an influence on related benthic resources. The increase in the level of NH4(+)-N had a negative impact on the economic clam species, while the sedimentary TOM showed positive correlation (P sediment conditions. Thus, the land-based runoff should be controlled for the protection of resources. Further effective sustainable management will be enhanced by giving serious

  11. Final report (2002-2004): Benthic macroinvertebrate communities of reconstructed freshwater tidal wetlands in the Anacostia River, Washington, D.C

    Science.gov (United States)

    Brittingham, K.D.; Hammerschlag, R.S.

    2006-01-01

    Considerable work has been conducted on the benthic communities of inland aquatic systems, but there remains a paucity of effort on freshwater tidal wetlands. This study characterized the benthic macroinvertebrate communities of recently reconstructed urban freshwater tidal wetlands along the Anacostia River in Washington, D.C. The focus of the study was on the two main areas of Kingman Marsh, which were reconstructed by the U.S. Army Corps of Engineers in 2000 using Anacostia dredge material. Populations from this 'new' marsh were compared to those of similarly reconstructed Kenilworth Marsh (1993) just one half mile upstream, the relic reference Dueling Creek Marsh in the upper Anacostia estuary and the outside reference Patuxent freshwater tidal marsh in an adjacent watershed. Benthic macro invertebrate organisms were collected using selected techniques for evaluation including the Ekman bottom grab sampler, sediment corer, D-net and Hester-Dendy sampler. Samples were collected at least seasonally from tidal channels, tidal mudflats, three vegetation/sediment zones (low, middle and high marsh), and pools over a 3-year period (late 2001-2004). The macroinvertebrate communities present at the marsh sites proved to be good indicators of disturbance and stress (Kingman Marsh), pollution, urban vs. rural location (Kenilworth and Patuxent), and similarities between reconstructed and remnant wetlands (Kenilworth and Dueling Creek). Macroinvertebrate density was significantly greater at Kingman Marsh than Kenilworth Marsh due to more numerous chironomids and oligochaetes. This may reflect an increase in unvegetated sediments at Kingman (even at elevations above natural mudflat) due to grazing pressure from over-abundant resident Canada geese. Unvegetated sediments yielded greater macroinvertebrate abundance but lower richness than vegetated marsh sites. Data collected from this study provides information on the extent that benthic macroinvertebrate communities can serve

  12. Benthic nutrient fluxes in the Eastern Gotland Basin (Baltic Sea) with particular focus on microbial mat ecosystems

    Science.gov (United States)

    Noffke, A.; Sommer, S.; Dale, A. W.; Hall, P. O. J.; Pfannkuche, O.

    2016-06-01

    Benthic fluxes and water column distributions of dissolved inorganic nitrogen (DIN) and total dissolved phosphate (PO43 -) were measured in situ at 7 sites across a redox gradient from oxic to anoxic bottom waters in the Eastern Gotland Basin (Baltic Sea). The study area was divided into the oxic zone (60 to ca. 80 m water depth, O2 > 30 μM), the hypoxic transition zone (HTZ, ca. 80 to 120 m, O2 ca. 120 m). Sediments in the HTZ were covered by mats of vacuolated sulfur bacteria. Ammonium (NH4+) fluxes in the deep basin and the HTZ were elevated at 0.6 mmol m- 2 d- 1 and 1 mmol m- 2 d- 1, respectively. Nitrate (NO3-) fluxes were directed into the sediment at all stations in the HTZ and were zero in the deep basin. PO43 - release was highest in the HTZ at 0.23 mmol m- 2 d- 1, with a further release of 0.2 mmol m- 2 d- 1 in the deep basin. Up-scaling the benthic fluxes to the Baltic Proper equals 109 kt yr- 1 of PO43 - and 266 kt yr- 1 of DIN. This is eight- and two-fold higher than the total external load of P (14 kt yr- 1) and DIN (140 kt yr- 1) in 2006 (HELCOM 2009b). The HTZ makes an important contribution to the internal nutrient loading in the Baltic Proper, releasing 70% of P (76 kt yr- 1) and 75% of DIN (200 kt yr- 1) despite covering only 51% of area.

  13. Benthic remineralisation rates in shelf and slope sediments of the northern Benguela upwelling margin

    Science.gov (United States)

    Neumann, Andreas; Lahajnar, Niko; Emeis, Kay-Christian

    2016-02-01

    The Benguela Upwelling System off Namibia is a region of intensive plankton production. Remineralisation of this biomass frequently causes the formation of an oxygen minimum zone. A part of the organic matter is further deposited on the broad shelf in form of an extensive mudbelt with high TOC concentrations. During February 2011 we retrieved sediment samples from shelf and slope sediment along the Namibian coast to establish fluxes of nutrients, oxygen, and N2 on the basis of pore water concentrations. In mudbelt sediment, fluxes were estimated as high as 8 mmol NH4+ m-2 d-1 and 0.9 mmol PO43 - m-2 d-1, which is probably attributable to the activity of large sulphur bacteria. Especially phosphate is mobilised from sediment overlain by oxygen deficient bottom water when and where bottom water oxygen concentrations fall below 50 μmol l-1. In comparison to nutrient transport by Southern Atlantic Central Water flowing onto the Namibian shelf, benthic nutrient fluxes of the mudbelt contribute less than 5% to the nutrient budget of the shelf.

  14. Benthic Foraminiferal Census Data from Louisiana Continental Shelf Cores, Gulf of Mexico

    Science.gov (United States)

    Osterman, Lisa E.; Kelly, Wendy S.; Ricardo, John P.

    2009-01-01

    An area of oxygen-depleted bottom- and subsurface-water (hypoxia = dissolved oxygen cores collected from the Continental Shelf of Louisiana (table 1), obtained as part of an initiative to investigate the geographic and temporal extent of hypoxia prior to 1985 in the Gulf of Mexico. Benthic foraminifers provide a method to track the development of hypoxia prior to 1985 (Blackwelder and others, 1996; Sen Gupta and others, 1996). Previous work (Osterman, 2003) has shown statistically that the relative occurrence of three low-oxygen-tolerant species represents the modern seasonal Louisiana hypoxia zone. The cumulative percentage of these three species (% Pseudononion atlanticum + % Epistominella vitrea, + % Buliminella morgani = PEB index of hypoxia) provides a way to investigate fluctuation in paleohypoxia. Interpretation of some of these cores is provided in Osterman and others (2005), Osterman and others (2008a,b), and Swarzenski and others (2008). Our hypothesis is that the increased relative abundance of PEB species in dated sediment cores accurately tracks past seasonal low-oxygen conditions on the Louisiana Shelf.

  15. Benthic primary producers are promoted by groundwater-borne nutrient inputs to an oligotrophic lake

    Science.gov (United States)

    Périllon, Cécile; Pöschke, Franziska; Lewandowski, Jörg; Hupfer, Michael; Hilt, Sabine

    2015-04-01

    Nutrient-rich groundwater may contribute significantly to the nutrient influx to lakes. We hypothesized that benthic primary producers may benefit from these nutrients and store them at the sediment-water interface, thus potentially preventing eutrophication processes in the open water. To test this hypothesis, we performed measurements and experiments in the shallow littoral areas of the oligotrophic Lake Stechlin in Germany (4.25 km², maximum depth 70 m). Periphyton grown on artificial substrates for four weeks was sampled at three different locations with groundwater influx and three respective locations without groundwater influx in summer 2013. A comparison between these zones with and without seepage revealed that groundwater discharge increased periphyton dry weight by 56 % and its areal phosphorus accumulation by 41% in 2013. Phosphorus stored in periphyton and macrophytes accounted to up to 46% of the phosphorous present in the epilimnion in summer. In addition, we conducted experiments with flow-through chambers installed in the sediment of an area with intense groundwater influx. We measured seepage, sampled pore water and compared the biomass of periphyton grown on artificial substrate and of submerged macrophytes (Potamogeton pectinatus L.) planted in open and closed-bottom (control) chambers. In open chambers with groundwater influx, periphyton dry weight increased up to 27% and macrophyte growth rate up to 52 % in comparison to closed-bottom chambers.

  16. Temporal and spatial variation of rocky shores intertidal benthic communities in Southeast Brazil

    Directory of Open Access Journals (Sweden)

    Gabriela C. Zamprogno

    2012-12-01

    Full Text Available The relationships between environmental factors and temporal and spatial variations of benthic communities of three rocky shores of the state of Espírito Santo, Southeast Brazil, were studied. Sampling was conducted every three months, from August 2006 to May 2007, using intersection points. Chthamalus bisinuatus (Pilsbry, 1916 (Crustacea and Brachidontes spp. (Mollusca were the most abundant taxa, occupying the upper level of the intertidal zone of the rocky shore. The species richness was higher at the lower levels. The invasive species Isognomon bicolor (C. B. Adams, 1845 (Mollusca occurred at low densities in the studied areas. The clustering analysis dendrogram indicated a separation of communities based on exposed and sheltered areas. According to the variance analyses, the communities were significantly different among the studied areas and seasons. The extent of wave exposure and shore slope influenced the species variability. The Setibão site showed the highest diversity and richness, most likely due to greater wave exposure. The communities showed greater variation in the lower levels where environmental conditions were less severe, relative to the other levels.

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

    Directory of Open Access Journals (Sweden)

    Patrick T Schwing

    Full Text Available 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

  18. The seasonal use of small-scale space by benthic species in a transiently hypoxic area

    Science.gov (United States)

    Doya, Carolina; Aguzzi, Jacopo; Chatzievangelou, Damianos; Costa, Corrado; Company, Joan Baptista; Tunnicliffe, Verena

    2016-02-01

    The use of small-scale space by benthos and its variation over the seasons in transiently hypoxic zones is poorly known. In this study, we examined the reciprocal spatial dispersion of the squat lobster (Munida quadrispina) and the slender sole (Lyopsetta exilis) according to oxygen concentrations at a VENUS platform of Ocean Networks Canada (ONC). This platform is located in a seasonally hypoxic zone at 96 m depth in the fjord of Saanich Inlet (British Columbia, Canada). We counted and located small as well as large squat lobsters and slender soles in digital still images during 1 year (2012-2013) also concomitantly obtained oxygen data. Images were subdivided in a squared grid to obtain relative density maps as a proxy for surface occupation and spatial autocorrelation. Pearson's chi-squared tests at a yearly scale, along with Dixon's spatial segregation index (S) for each possible pair among the studied groups, showed a significant absence of overlap. The same analyses by month and cross-correlation between oxygen and S showed that while the dispersion patterns of the large squat lobsters seemed to be driven mainly by the morphology of the seafloor, an effect of hypoxia was found in the small squat lobsters and the slender soles levels of aggregation. Small squat lobster sought seabed protrusions, such as sponges, to reach more oxygenated water. The slender sole's space occupation decreased significantly, being forced to retreat when the squat lobsters' abundance peaked as a result of what appeared to be a seasonal reproduction event in early summer. Our results contribute to the understanding of the ways in which oxygen levels modulate substrate use by benthic species in the framework of a global expansion of hypoxia in coastal and ocean areas.

  19. Southern Polar Front macroecological and biogeographical insights gained from benthic Ostracoda

    Science.gov (United States)

    Brandão, Simone N.; Vital, Helenice; Brandt, Angelika

    2014-10-01

    The Southern Ocean is one of the least known marine ecosystems on Earth, but the importance of understanding its biological and geochemical characteristics are urgent, because of the fast changing climate. Primary productivity is a key factor in ecosystem functioning, since this is the only process (except for the rare chemosynthesis) transforming solar energy into organic material, which can later be processed by all other living beings. Herein we investigate how primary productivity in the euphotic zone influences the biodiversity on the sea bed at abyssal depths, using Ostracoda (Crustacea) as a model. We also discuss the biogeographical pattern of the ostracod fauna. Samples collected from the Atlantic sector of the Southern Ocean close to the Southern Polar Front (i.e. ~51°S) during the SYSTCO II expedition are the basis for our analyses. For the statistical tests, we used samples collected with an epibenthic sledge, which has the advantages of sampling a far larger area than traditional gears (i.e. grabs and corers), and also collect Myodocopida and Halocyprida rarely recorded in ostracod studies. However, because of its large mesh size (i.e. 300 and 500 μm) the epibenthic sledge fails to recover small sized ostracods. Most benthic and benthopelagic ostracod species inhabiting the Southern Polar Front region are either endemic to the Southern Ocean or occur close to it. We conclude that ostracod assemblages living below areas of high primary productivity seem to be different to those below low productivity zones, but that assemblages living west of the Mid-Atlantic Ridge are not significantly distinct from the ones living to the east of this putative barrier.

  20. First phase monitoring studies of simulated benthic disturbance delineating movement of fine particles in the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Valsangkar, A.B.

    Benthic disturbance due to future deep-sea polymetallic nodule mining would involve extensive sediment plume generation and resedimentation on the sea floor. In order to evaluate the effects of resedimentation on benthic environment, the Indian...

  1. Bacterial standing stock, meiofauna and sediment-nutrient characteristics: Indicators of benthic disturbance in the Central Indian Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Raghukumar, C.; LokaBharathi, P.A.; Ansari, Z.A.; Nair, S.; Ingole, B.S.; Sheelu, G.; Mohandass, C.; Nath, B.N.; Rodrigues, N.

    As a part of the environmental impact assessment studies for polymetallic nodule mining, the effect of simulated "benthic disturbance" caused by a benthic hydraulic disturber was studied in the Central Indian Basin (CIB). The abundance...

  2. Interlinking backscatter, grain size and benthic community structure

    Science.gov (United States)

    McGonigle, Chris; Collier, Jenny S.

    2014-06-01

    The relationship between acoustic backscatter, sediment grain size and benthic community structure is examined using three different quantitative methods, covering image- and angular response-based approaches. Multibeam time-series backscatter (300 kHz) data acquired in 2008 off the coast of East Anglia (UK) are compared with grain size properties, macrofaunal abundance and biomass from 130 Hamon and 16 Clamshell grab samples. Three predictive methods are used: 1) image-based (mean backscatter intensity); 2) angular response-based (predicted mean grain size), and 3) image-based (1st principal component and classification) from Quester Tangent Corporation Multiview software. Relationships between grain size and backscatter are explored using linear regression. Differences in grain size and benthic community structure between acoustically defined groups are examined using ANOVA and PERMANOVA+. Results for the Hamon grab stations indicate significant correlations between measured mean grain size and mean backscatter intensity, angular response predicted mean grain size, and 1st principal component of QTC analysis (all p response predicted mean grain size (r2 = 0.692; p response predicted grain size (p < 0.001), and QTC class (p = 0.009). Mean grain size (Clamshell) shows a significant difference between groups for mean backscatter (p = 0.001); other methods were not significant. PERMANOVA for the Hamon abundance shows benthic community structure was significantly different between acoustic groups for all methods (p ≤ 0.001). Overall these results show considerable promise in that more than 60% of the variance in the mean grain size of the Clamshell grab samples can be explained by mean backscatter or acoustically-predicted grain size. These results show that there is significant predictive capacity for sediment characteristics from multibeam backscatter and that these acoustic classifications can have ecological validity.

  3. Organic matter and benthic metabolism in Lake Illawarra, Australia

    Science.gov (United States)

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

    2006-10-01

    Carbon and nitrogen contents (total organic carbon and total nitrogen), chlorophyll-a concentrations in surface sediments and benthic sediment-water fluxes of oxygen and carbon dioxide were investigated at five stations in Lake Illawarra (Australia) to compare the sources/quality of sedimentary organic matter and the characteristics of diagenesis and benthic biogeochemical processes for different primary producers (e.g., seagrass, microphytobenthos and macroalgae) and/or sediment types (sand or mud). The unvegetated sediments showed lower C/N ratios (with the lowest value occurring in the deep organic-rich muddy site) than the seagrass ( Ruppia or Zostera) beds, which may be due to the contribution of microalgae (mainly diatoms) to the sedimentary organic matter pool. This was also supported by the detection of microalgal pigments in the bare sediments. On an annual basis, seagrass beds exhibited the highest gross primary productivity (O 2 or TCO 2 fluxes), while the lowest rates occurred in the deep central basin of the Lake. Seasonally, there was a general trend of highest production in spring or summer, and lowest production in winter or autumn. Organic carbon oxidation scenarios, evaluated by either calcium carbonate dissolution or sulfate reduction models, indicated that both models can explain organic matter mineralization. Trophic status was evaluated using different indices including benthic trophic state index, net O 2 fluxes and P/ R ratios for Lake Illawarra, which led to similar trophic classifications in general, and also the same trends in spatial and seasonal variations. Overall, these data indicated that the Lake was heterotrophic on an annual basis, as the total community carbon respiration exceeded production, and this supported an earlier LOICZ mass balance/stoichiometric modelling conclusion.

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

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

    2012-12-01

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

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

    Science.gov (United States)

    Barnes, D K A

    2015-09-21

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

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

    Directory of Open Access Journals (Sweden)

    Paul A Montagna

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

  8. Antarctic Porifera database from the Spanish benthic expeditions

    Directory of Open Access Journals (Sweden)

    Pilar Rios

    2014-04-01

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

  9. Antarctic Porifera database from the Spanish benthic expeditions.

    Science.gov (United States)

    Rios, Pilar; Cristobo, Javier

    2014-01-01

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

  10. Matching biological traits to environmental conditions in marine benthic ecosystems

    Science.gov (United States)

    Bremner, J.; Rogers, S. I.; Frid, C. L. J.

    2006-05-01

    The effects of variability in environmental conditions on species composition in benthic ecosystems are well established, but relatively little is known about how environmental variability relates to ecosystem functioning. Benthic invertebrate assemblages are heavily involved in the maintenance of ecological processes and investigation of the biological characteristics (traits) expressed in these assemblages can provide information about some aspects of functioning. The aim of this study was to establish and explore relationships between environmental variability and biological traits expressed in megafauna assemblages in two UK regions. Patterns of trait composition were matched to environmental conditions and subsets of variables best describing these patterns determined. The nature of the relationships were subsequently examined at two separate scales, both between and within the regions studied. Over the whole area, some traits related to size, longevity, reproduction, mobility, flexibility, feeding method, sociability and living habit were negatively correlated with salinity, sea surface temperature, annual temperature range and the level of fishing effort, and positively associated with fish taxon richness and shell content of the substratum. Between the two regions, reductions in temperature range and shell content were associated with infrequent relative occurrences of short-lived, moderately mobile, flexible, solitary, opportunistic, permanent-burrow dwelling fauna and those exhibiting reproductive strategies based on benthic development. Relationships between some traits and environmental conditions diverged within the two regions, with increases in fishing effort and shell content of the substratum being associated with low frequencies of occurrence of moderately mobile and moderately to highly flexible fauna within one region, but high frequencies in the other. These changes in trait composition have implications for ecosystem processes, with, for

  11. Accumulation of 210Po by benthic marine algae

    International Nuclear Information System (INIS)

    The accumulation of polonium 210Po by various species of benthic marine seaweeds collected from 4 different points on the coast of Rio de Janeiro, showed variations by species and algal groups. The highest value found was in red alga, Plocamium brasiliensis followed by other organisms of the same group. In the group of the brown alga, the specie Sargassum stenophylum was outstanding. The Chlorophyta presented the lowest content of 210Po. The algae collected in open sea, revealed greater concentration factors of 210Po than the same species living in bays. The siliceous residue remaining after mineralization of the algae did not interfere with the detection of polonium. (author)

  12. Metabolism of polycyclic aromatic hydrocarbons in benthic microcosms

    International Nuclear Information System (INIS)

    [12-14C]Benz(a)anthracene was used as a tracer to follow the metabolism of polycyclic aromatic hydrocarbons in benthic microcosms containing fine sediment and polychaetes. Experiments were conducted using both large (230 L) and small (2 L) microcosms where the fate of the radiolabel was followed for up to 42 days in the water column, in the sediment reservoir, and in two species of polychaetes (Nereis virens and Nephtys incisa). Benz(a)anthracene was extensively metabolized in these microcosms, although the degree of metabolism was highly dependent on how the radiolabel was introduced to the system and the presence of suspended particulates and an established microbial community

  13. Complexity and simplification in understanding recruitment in benthic populations

    KAUST Repository

    Pineda, Jesús

    2008-11-13

    Research of complex systems and problems, entities with many dependencies, is often reductionist. The reductionist approach splits systems or problems into different components, and then addresses these components one by one. This approach has been used in the study of recruitment and population dynamics of marine benthic (bottom-dwelling) species. Another approach examines benthic population dynamics by looking at a small set of processes. This approach is statistical or model-oriented. Simplified approaches identify "macroecological" patterns or attempt to identify and model the essential, "first-order" elements of the system. The complexity of the recruitment and population dynamics problems stems from the number of processes that can potentially influence benthic populations, including (1) larval pool dynamics, (2) larval transport, (3) settlement, and (4) post-settlement biotic and abiotic processes, and larval production. Moreover, these processes are non-linear, some interact, and they may operate on disparate scales. This contribution discusses reductionist and simplified approaches to study benthic recruitment and population dynamics of bottom-dwelling marine invertebrates. We first address complexity in two processes known to influence recruitment, larval transport, and post-settlement survival to reproduction, and discuss the difficulty in understanding recruitment by looking at relevant processes individually and in isolation. We then address the simplified approach, which reduces the number of processes and makes the problem manageable. We discuss how simplifications and "broad-brush first-order approaches" may muddle our understanding of recruitment. Lack of empirical determination of the fundamental processes often results in mistaken inferences, and processes and parameters used in some models can bias our view of processes influencing recruitment. We conclude with a discussion on how to reconcile complex and simplified approaches. Although it

  14. Antarctic Porifera database from the Spanish benthic expeditions

    OpenAIRE

    Pilar Rios; Javier Cristobo

    2014-01-01

    The information about the sponges in this dataset is derived from the samples collected during five Spanish Antarctic expeditions: Bentart 94, Bentart 95, Gebrap 96, Ciemar 99/00 and Bentart 2003. Samples were collected in the Antarctic Peninsula and Bellingshausen Sea at depths ranging from 4 to 2044 m using va­rious sampling gears.The Antarctic Porifera database from the Spanish benthic expeditions is unique as it provides in­formation for an under-explored region of the Southern Oc...

  15. ECOLOGICAL ASPECTS OF BENTHIC COMMUNITIES FROM SOMESUL CALD CATCHMENT AREA

    Directory of Open Access Journals (Sweden)

    Karina Battes

    2001-01-01

    Full Text Available The present paper represents a preliminary study of periphyton and zoobenthos community from the Someşul Cald catchment area. Zoobenthos was sampled seasonally during 2000. Benthic community structure was similar at the five sampling sites. Thus, mayflies and chironomids recorded high numerical percentage abundances and densities. Oligochaetes, water mites and caddisflies were identified to species level. 38 Oligochaeta, 28 water mite and 12 caddis fly species were found in the sampling period. The samplings collected in the year 2001 included 80 algal species belonging to 5 phyla. Diatoms (Bacillariophyta dominated both qualitatively and quantitatively at all sampling sites.

  16. Benthic polychaetes as good indicators of anthropogenic impact

    Digital Repository Service at National Institute of Oceanography (India)

    Sivadas, S.; Ingole, B.S.; Nanajkar, M.

    ) 225-231. 8 Parulekar A H, Dhargalkar V K & Singbal S Y S. Benthic studies in Goa estuaries: Part III- Annual cycle of macrofaunal distribution, production and trophic relations. Indian J. Mar. Sci., 9 (1980) 189-200. 9 Ansari Z A, Ingole B S..., India: an overview of 23 years of investigation and monitoring. Helgoland. Meeresunters., 49 (1995) 633-645. 32 Fauchald K & Jumars P A, The diet of worms: A study of polychaete feeding guilds. Oceanogr. Mar. Biol. A. Rev. 17 (1979) 193-284. 33...

  17. Modeling food web interactions in benthic deep-sea ecosystems. A practical guide

    NARCIS (Netherlands)

    Soetaert, K.E.R.; Van Oevelen, D.J.

    2009-01-01

    Deep-sea benthic systems are notoriously difficult to sample. Even more than for other benthic systems, many flows among biological groups cannot be directly measured, and data sets remain incomplete and uncertain. In such cases, mathematical models are often used to quantify unmeasured biological i

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

    NARCIS (Netherlands)

    Gontikaki, E.; Van Oevelen, D.; Soetaert, K.E.R.; Prof. Witte, U.

    2011-01-01

    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 reveale

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

    NARCIS (Netherlands)

    Van Oevelen, D.; Bergmann, M.; Soetaert, K.E.R.; Bauerfeind, E.; Hasemann, C.; Klages, M.; Schewe, I.; Soltwedel, T.; Budaeva, N.E.

    2011-01-01

    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 HAUSGAR

  20. Application of the Benthic Ecosystem Quality Index 2 to benthos in Dutch transitional and coastal waters

    NARCIS (Netherlands)

    Loon, van W.M.G.M.; Boon, A.R.; Gittenberger, A.; Walvoort, D.J.J.; Lavaleye, M.; Duineveld, G.C.A.; Verschoor, A.J.

    2015-01-01

    The Benthic Ecosystem Quality Index 2 (BEQI2) is the Dutch multi-metric index (MMI) for assessing the status and trend of benthic invertebrates in transitional and coastal waters for the Water Framework Directive (WFD). It contains the same indicators, i.e. species richness, Shannon index and AMB

  1. Application of the Benthic Ecosystem Quality Index 2 to benthos in Dutch transitional and coastal waters

    NARCIS (Netherlands)

    Van Loon, W.M.G.M.; Boon, A.R.; Gittenberger, A.; Walvoort, D.J.J.; Lavaleye, M.S.S.; Duineveld, G.C.A.; Verschoor, A.J.

    2015-01-01

    The Benthic Ecosystem Quality Index 2 (BEQI2) is the Dutch multi-metric index (MMI) for assessing the status and trend of benthic invertebrates in transitional and coastal waters for the Water Framework Directive (WFD). It contains the same indicators, i.e. species richness, Shannon index and AMBI,

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

    Science.gov (United States)

    King, Jeffrey N.

    2011-01-01

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

  3. Human exploitation and benthic community structure on a tropical intertidal mudflat

    NARCIS (Netherlands)

    Boer, de W.F.; Prins, H.H.T.

    2002-01-01

    Human exploitation of intertidal marine invertebrates is known to alter benthic community structure. This study describes the impact that harvesting by women and children has on the intertidal community structure of the mudflats of the Saco on Inhaca Island, Mozambique, by comparing the benthic comm

  4. Human exploitation and benthic community structure on a tropical intertidal flat

    NARCIS (Netherlands)

    de Boer, WF; Prins, HHT

    2002-01-01

    Human exploitation of intertidal marine invertebrates is known to alter benthic community structure. This study describes the impact that harvesting by women and children has on the intertidal community structure of the mudflats of the Saco on Inhaca Island, Mozambique, by comparing the benthic comm

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

    Science.gov (United States)

    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...

  6. PUHO_BenthicHabitats - Benthic habitat of the coral reef ecosystem off the coast of Puuhonua O Honaunau (PUHO) National Historical Park on the Kona Coast of Hawaii.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A benthic habitat polygon coverage has been created of the coral reef ecosystem off the coast of Pu'uhonua O Honaunau (PUHO) National Historical Park on the Kona...

  7. KAHO_BenthicHabitats - Benthic habitat of the coral reef ecosystem within and adjacent to Kaloko-Honokohau National Historical Park (KAHO) on the Kona Coast of Hawaii.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A benthic habitat polygon coverage has been created of the coral reef ecosystem within and adjacent to Kaloko-Honokohau National Historical Park (KAHO) on the Kona...

  8. PUHE_BenthicHabitats - Benthic habitat of the coral reef ecosystem off the coast of Puukohola Heiau (PUHE) National Historic Site on the Kona Coast of Hawaii.

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — A benthic habitat polygon coverage has been created of the coral reef ecosystem off the coast of Pu'ukohola Heiau (PUHE) National Historic Site on the Kona Coast of...

  9. Seasonal rates of benthic primary production in a Greenland fjord measured by aquatic eddy correlation

    DEFF Research Database (Denmark)

    M. Attard, Karl; Glud, Ronnie; McGinnis, Daniel F.;

    2014-01-01

    We present the first year-round estimates of benthic primary production at four contrasting shallow (3–22 m depth) benthic habitats in a southwest Greenland fjord. In situ measurements were performed using the noninvasive aquatic eddy-correlation (EC) oxygen (O2) flux method. A series of high-qua...... document the importance of benthic photosynthesis on an ecosystem level and indicate that the benthic phototrophic compartment should be accounted for when assessing carbon and nutrient budgets as well as responses of coastal Arctic ecosystems to climate change.......-quality multiple-day EC data sets document the presence of a year-round productive benthic phototrophic community. The shallow-water sites were on average autotrophic during the spring and summer months, up to 43.6 mmol O2 m22 d21, and heterotrophic or close to metabolic balance during the autumn and winter...

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

    Science.gov (United States)

    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.

  11. Transfer of radiocaesium from contaminated bottom sediments to marine organisms through benthic food chains in post-Fukushima and post-Chernobyl periods

    Science.gov (United States)

    Bezhenar, Roman; Jung, Kyung Tae; Maderich, Vladimir; Willemsen, Stefan; de With, Govert; Qiao, Fangli

    2016-05-01

    After the earthquake and tsunami on 11 March 2011 damaged the Fukushima Dai-ichi Nuclear Power Plant (FDNPP), an accidental release of a large amount of radioactive isotopes into both the air and the ocean occurred. Measurements provided by the Japanese agencies over the past 5 years show that elevated concentrations of 137Cs still remain in sediments, benthic organisms, and demersal fishes in the coastal zone around the FDNPP. These observations indicate that there are 137Cs transfer pathways from bottom sediments to the marine organisms. To describe the transfer quantitatively, the dynamic food chain biological uptake model of radionuclides (BURN) has been extended to include benthic marine organisms. The extended model takes into account both pelagic and benthic marine organisms grouped into several classes based on their trophic level and type of species: phytoplankton, zooplankton, and fishes (two types: piscivorous and non-piscivorous) for the pelagic food chain; deposit-feeding invertebrates, demersal fishes fed by benthic invertebrates, and bottom omnivorous predators for the benthic food chain; crustaceans, mollusks, and coastal predators feeding on both pelagic and benthic organisms. Bottom invertebrates ingest organic parts of bottom sediments with adsorbed radionuclides which then migrate up through the food chain. All organisms take radionuclides directly from water as well as food. The model was implemented into the compartment model POSEIDON-R and applied to the north-western Pacific for the period of 1945-2010, and then for the period of 2011-2020 to assess the radiological consequences of 137Cs released due to the FDNPP accident. The model simulations for activity concentrations of 137Cs in both pelagic and benthic organisms in the coastal area around the FDNPP agree well with measurements for the period of 2011-2015. The decrease constant in the fitted exponential function of simulated concentration for the deposit-feeding invertebrates (0.45 yr-1

  12. Anti-inflammatory activity in selected Antarctic benthic organisms

    Directory of Open Access Journals (Sweden)

    Juan eMoles

    2014-07-01

    Full Text Available Antarctic benthos was prospected in search for anti-inflammatory activity in polar benthic invertebrates, in two different geographical areas: deep-bottoms of the Eastern Weddell Sea and shallow-waters of the South Shetland Islands. A total of 36 benthic algae and invertebrate species were selected to perform solubility tests in order to test them for anti-inflammatory activity. From these, ethanol extracts of ten species from five different phyla resulted suitable to be studied in cell macrophage cultures (RAW 264.7. Cytotoxicity (MTT method and production of inflammatory mediators (prostaglandin E2, leukotriene B4, interleukin-1 were determined at three extract concentrations (50, 125, 250 g/mL. Bioassays resulted in four different species showing anti-inflammatory activity corresponding to three sponges: Mycale (Oxymycale acerata, Isodictya erinacea, and I. toxophila; and one hemichordate: Cephalodiscus sp. These results show that Antarctic sessile invertebrates may have great value as a source of lead compounds with potential pharmaceutical applications.

  13. Biomonitoring polluted sediments in Arctic regions - possibilities and challenges using benthic foraminifera. Case studies from northern Norway

    Science.gov (United States)

    Skirbekk, Kari; Dijkstra, Noortje; Junttila, Juho; Sternal, Beata; Pedersen, Kristine Bondo; Forwick, Matthias; Carroll, JoLynn

    2016-04-01

    Biomonitoring pollution in marine environments using benthic foraminifera assemblages have proven to be a valid method for many regions. Two important reasons for their suitability are their sensitivity to changes in the environment and their rapid response time due to short life cycles. In addition, they are preserved in the sedimentary record, allowing for baseline studies of conditions prior to introduction of contaminants. Species of benthic foraminifera that appear to tolerate polluted sediments are referred to as opportunistic species. This notion is in general used for species able to dominate environments that are too stressful for most species. The high latitude setting of the northern Norwegian coastal zone experience high seasonality and, hence, largely changing conditions throughout a year: variations in water mass domination, freshwater influence, temperature and current velocity. It is possible that an environment like this is inhibited by a higher amount of opportunistic species generally thriving under high stress conditions. This might make the use of benthic foraminifera for biomonitoring more challenging, as the faunal compositions may be a result of a complex set of processes. Consequently, large datasets are necessary in order to make reliable conclusions, which in time may be used as generalized guidelines for biomonitoring in this geographical area. Here, we present preliminary results of benthic foraminiferal assemblages from two sites in Finnmark, northern Norway, which have been exposed to pollution. The main site is Repparfjorden, where the inner parts of the fjord were used as a submarine waste deposal site for mine tailings from a local copper mine during the 1970´s. Results from four marine sediment cores (10-20 cm long) containing sediments classified to be in moderate to very bad state (according to Norwegian sediment quality criteria) are presented. The contamination is seen in intervals of elevated copper content dated to the 1970

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

    Science.gov (United States)

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

    2012-04-01

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

  15. The role of benthic macrofauna on nitrogen cycling in eutrophic lake sediment

    Energy Technology Data Exchange (ETDEWEB)

    Svensson, J.M.

    1998-12-01

    This thesis concerns the role of sediment-living macrobenthos in the cycling of nitrogen species and nitrogen transformation in eutrophic freshwater sediments. In my thesis I have, employing {sup 15}N-isotope techniques in laboratory experiments, shown the importance of infaunal chironomid larvae and oligochaetes on denitrification in eutrophic lake sediments. Investigated benthic organisms not only expand the sediment surface with their permanent or non-permanent burrow constructions, they also transport water through the burrows continuously. This behaviour of intermittent water-pumping activity, provides the burrows with oxygen, and in addition, mediates the supply of nitrate to denitrifying zones. The highly dynamic oxygen climate within and narrow oxic zones around burrows, due to their radial geometry, provides a very short diffusion path for nitrate into surrounding anoxic zones. In my studies rates of denitrification were enhanced c. 3 to 6-fold by the influence of chironomids (Chironomus plumosus) and c. 2-fold by the influence of oligochaetes at comparable biomass. The difference in degree of stimulation is explained by species-specific habitat exploitation which could also be observed between different tube-dwelling species of chironomids. Besides chironomid biomass, the degree of enhancement of denitrification by chironomids was dependent on nitrate concentration in the overlying water, and water temperature. Nitrification was also seen to be stimulated by the infaunal macrobenthos but to a lesser degree than denitrification. It is suggested that bioturbated eutrophic sediment, under predominantly oxic bottom water conditions may act more pronouncedly as a sink for inorganic nitrogen relative to non-bioturbated sediment, and that bioturbated sediment above all, may be an important factor contributing to lowered transport of nitrogen to the coast. In order to sustain high nitrogen removal capacity in wetlands, ponds and lakes, it is further suggested

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

    Directory of Open Access Journals (Sweden)

    K. R. N. Anthony

    2013-02-01

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

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

    Directory of Open Access Journals (Sweden)

    K. R. N. Anthony

    2013-07-01

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

  18. Response of benthic macrofauna to an oil pollution: Lessons from the “Prestige” oil spill on the rocky shore of Guéthary (south of the Bay of Biscay, France)

    Science.gov (United States)

    Castège, Iker; Milon, Emilie; Pautrizel, Françoise

    2014-08-01

    The benthic community on the rocky foreshore of Guéthary (France) has been monitored since 2002. The standardized and quantitative monitoring method counts 20 geographically referenced quadrats spread on three littoral zones: upper mediolittoral, lower mediolittoral and infralittoral zones. The setting up of this monitoring occurred when the “Prestige” sunk close to the Finistere Cape in Galicia (Spain). The oil slick following the shipwreck impacted the Guéthary foreshore in early 2003. After the “Prestige” oil spill, the taxonomic richness decreased in the studied area with a loss of 16 species - from 57 in 2002 (before the shipwreck) to 41 species in 2004. Two or 3 years later, taxonomic richness increased to a level observed prior to the oil spill. Along the years, temporal variations in community structure of benthic macrofauna are revealed by detailed analysis. Some polluo-sensitive species disappeared after 2002 and have not reappeared yet (e.g.: Hymeniacidon perlevis). Some others reappeared two or three years after the spill or even later (e.g.: Amphipholis squamata, Botryllus schlosseri, Calliostoma zizyphinum, Echinus esculentus, etc.). Noteworthy changes were found in 2004 driven by the sudden increase in abundance of grazers. The following years, these abundances went back to a stable level. The benthic community seemed to recover almost 5 years later, although a new composition of macrofauna populations was observed. In overall aspect, the complexity of the benthic ecosystem response to oil spills confirms the need of regularly updated baselines to assess the impact of pollutions and more generally to maintain marine biodiversity.

  19. Evaluation of benthic macroinvertebrate assemblage for disturbance zonation in urban rivers using multivariate analysis: Implications for river management

    Science.gov (United States)

    Shah, Ram Devi Tachamo; Shah, Deep Narayan

    2013-08-01

    River pollution has tremendously increased in the major cities of South Asia, where the rivers have become a repository for domestic, agricultural, municipal and industrial wastes. This study presents the evaluation of benthic macroinvertebrate assemblage as a means of assessing ecological status, determining different disturbance zones and identifying environmental variables and stressors that deteriorate the river ecosystem. In total, 20 sites in 36-km stretch of the main stem of the Bagmati River and 7 sites on its tributaries were selected for sampling in the post-monsoon and pre-monsoon seasons during the time period 2008-2010. The Ganga River System Biotic Score (GRSbios) index was applied to determine the ecological status. The ecological status of the different Bagmati River stretches ranged from reference (Class 1) to extremely polluted (Class 5). We identified three types of disturbance zones along the river, ranging from minimally polluted to extremely polluted. A river corridor survey was conducted to identify any river stressing factors, revealing a sharp deterioration of the river from upstream to downstream with increasing concentrations of chloride and ortho-phosphate phosphorus. Effluents and Activities and Facilities were found to be the major stressing factors to the river ecosystem. The information gained should help water managers find the most time-efficient and cost-effective measures to address river degradation.

  20. Evaluation of benthic macroinvertebrate assemblage for disturbance zonation in urban rivers using multivariate analysis: Implications for river management

    Indian Academy of Sciences (India)

    Ram Devi Tachamo Shah; Deep Narayan Shah

    2013-08-01

    River pollution has tremendously increased in the major cities of South Asia, where the rivers have become a repository for domestic, agricultural, municipal and industrial wastes. This study presents the evaluation of benthic macroinvertebrate assemblage as a means of assessing ecological status, determining different disturbance zones and identifying environmental variables and stressors that deteriorate the river ecosystem. In total, 20 sites in 36-km stretch of the main stem of the Bagmati River and 7 sites on its tributaries were selected for sampling in the post-monsoon and pre-monsoon seasons during the time period 2008–2010. The Ganga River System Biotic Score (GRSbios) index was applied to determine the ecological status. The ecological status of the different Bagmati River stretches ranged from reference, class 1 to class 5 (extremely polluted). We identified three types of disturbance zones along the river, ranging from minimally polluted to extremely polluted. A river corridor survey was conducted to identify any river stressing factors, revealing a sharp deterioration of the river from upstream to downstream with increasing concentrations of chloride and ortho-phosphate phosphorus. Effluents and Activities and Facilities were found to be the major stressing factors to the river ecosystem. The information gained should help water managers find the most time-efficient and cost-effective measures to address river degradation.

  1. Functional response of midsummer planktonic and benthic communities in the Neva Estuary (eastern Gulf of Finland to anthropogenic stress

    Directory of Open Access Journals (Sweden)

    Sergey M. Golubkov

    2003-03-01

    Full Text Available Long-term hydrobiological research has shown that the functioning of the ecosystem of the Neva Estuary, one of the largest Baltic estuaries, has changed greatly since the beginning of the 20th century. Ineffective local water management in St. Petersburg during thelast twenty years has stimulated the development of a natural "biological plug" in the salt barrier zone in the inner part ofthe estuary and has altered the ecosystem's functioning. These changes include an increase in primary production, in the primary production:organic matter decomposition ratio, and in pelagic-benthic coupling. It has also given rise to filamentous algae blooms and intensive secondary pollution in the coastal zone of the Neva Estuary. The primary production of phytoplankton in the inner part of the estuary has reached 2.3 gC m-2, that of the filamentous algae Cladophora glomerata 5.5 gC m-2 these figures are much higher than in other regions of the Gulf of Finland.

  2. Towards a framework for the quantitative assessment of trawling impact on the seabed and benthic ecosystem

    DEFF Research Database (Denmark)

    Rijnsdorp, A. D.; Bastardie, Francois; Bolam, S.G.; Buhl-Mortensen, L.; Eigaard, Ole Ritzau; Hamon, Katell; Hiddink, J.G.; Hintzen, Niels T.; Ivanovic, A.; Kenny, A.; Laffargue, A.; Nielsen, J. Rasmus; O’Neill, F.G.; Polet, H.; Sala, A.; Smith, C.; van Denderen, Pieter Daniël; Kooten, Tobias van; Zenging, M.

    considers the physical effects of trawl gears on the seabed, on marine taxa, and on the functioning of the benthic ecosystem. Within the frame- work, a reductionist approach is applied that breaks down a fishing gear into its components, and a number of biological traits are chosen to de- termine either the...... scraping of the seabed, sediment mobilization, and penetration, is a function of the mass, size, and speed of the individual component. The impact of the elements on the benthic community is quantified using a biological-trait approach that considers the vulnerability of the benthic community to trawl...

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

    DEFF Research Database (Denmark)

    Stief, P.

    2013-01-01

    (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...... significantly enhance nitrous oxide emission from shallow aquatic ecosystems. The beneficial effect of benthic macrofauna on fixed nitrogen removal through coupled nitrification-denitrification can thus be offset by the concurrent release of (i) ammonium that stimulates aquatic primary production and (ii......) nitrous oxide that contributes to global warming. Overall, benthic macrofauna intensifies the coupling between benthos, pelagial, and atmosphere through enhanced turnover and transport of nitrogen....

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

    Science.gov (United States)

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

    2016-04-01

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

  5. Deconstructing the C/T OAE (~94 Ma): the Plenus Cold Event/Benthic Oxic Event and its geochemical consequences

    Science.gov (United States)

    Jenkyns, Hugh; Dickson, Alex; Ruhl, Micha; Van den Boorn, Sander

    2014-05-01

    The so-called Plenus Cold Event (M. geslinianum Zone: ~94 Ma) occurred during the early stages of the Cenomanian-Turonian Oceanic Anoxic Event, as defined by the characteristic positive carbon-isotope excursion in carbonate and organic matter. The event is marked in Europe by the southward invasion of a boreal fauna, including the belemnite Praeactinocamax plenus, a shift to heavier oxygen-isotope values in bulk chalk, and evidence for a drop in pCO2 based on the offset between carbon-isotope ratios in organic and carbonate carbon. TEX86 values from mid-latitude and palaeo-equatorial DSDP/ODP Atlantic sites suggest a cooling of ~4->5°C over this interval. In the Western Interior Seaway of North America, and in the equatorial proto-Atlantic, this interval was characterized by repopulation of the seafloor by benthic foraminifera (the Benthic Oxic Event), indicating regional re-oxygenation of bottom waters. Neodymium-isotope ratios from fish teeth from the English Chalk and the equatorial Atlantic indicate profound changes at this time in the composition of watermasses, whose derivation from Arctic regions is likely. Although data from south of the Equator are currently lacking, redox-sensitive geochemical species from a number of sections suggest profound regional changes in the dissolved oxygen levels of the sea floor at this time. These geochemical species include iodine (increase in I/Ca ratios as a response to increased availability of iodate as opposed to the reduced form, iodide, in seawater); sulphur-isotope ratios (decrease in δ34SCAS due to oxidation of marine pyrite in seawater and sediment) and local decrease in molybdenum-isotope ratios (δ98/95Mo) in sediment due to preferential adsorption of the lighter isotope into Fe-Mn oxyhydroxide phases stabilized under more oxygenated conditions. The predicted global increase in seawater δ98/95Mo over this interval remains to be established.

  6. Abyssal fauna of the UK-1 polymetallic nodule exploration claim, Clarion-Clipperton Zone, central Pacific Ocean: Echinodermata

    OpenAIRE

    Glover, Adrian G.; Wiklund,Helena; Rabone, Muriel; Amon, Diva J; Smith, Craig R.; O'Hara,Tim; Mah, Christopher L.; Dahlgren, Thomas G

    2016-01-01

    Abstract We present data from a DNA taxonomy register of the abyssal benthic Echinodermata collected as part of the Abyssal Baseline (ABYSSLINE) environmental survey cruise ‘AB01’ to the UK Seabed Resources Ltd (UKSRL) polymetallic-nodule exploration claim ‘UK-1’ in the eastern Clarion-Clipperton Zone (CCZ), central Pacific Ocean abyssal plain. Morphological and genetic data are presented for 17 species (4 Asteroidea , 4 Crinoidea , 2 Holothuroidea and 7 Ophiuroidea ) identified by a combinat...

  7. Hardy exotics species in temperate zone: can “warm water” crayfish invaders establish regardless of low temperatures?

    OpenAIRE

    Lukáš Veselý; Miloš Buřič; Antonín Kouba

    2015-01-01

    The spreading of new crayfish species poses a serious risk for freshwater ecosystems; because they are omnivores they influence more than one level in the trophic chain and they represent a significant part of the benthic biomass. Both the environmental change through global warming and the expansion of the pet trade increase the possibilities of their spreading. We investigated the potential of four “warm water” highly invasive crayfish species to overwinter in the temperate zone, so as to p...

  8. Selective responses of benthic foraminifera to thermal pollution

    Science.gov (United States)

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

    2016-04-01

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

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

    Science.gov (United States)

    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.

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

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

    2008-04-01

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

  12. Benthic processes in fresh water fluffy sediments undergoing resuspension

    Directory of Open Access Journals (Sweden)

    Daniele Longhi

    2013-02-01

    Full Text Available In the Po river plain relict freshwater wetlands are characterised by a low free water to emergent macrophyte surface ratio, rapid infilling and fluffy sediments, undergoing frequent resuspension. Particle mixing should alter the steep gradients of dissolved gas, nutrient and organic matter quality that generally characterise sediments, with implications for benthic processes. Sediment features and solute fluxes were studied from December 2003 to February 2005 within the Busatello swamp complex (Northern Italy by means of a combination of core incubation, porewater extraction and microprofiling. At the study site, along a 10 cm vertical profile, sediment organic matter content (32.5%, porosity (0.94 and density (1.02 g cm–3 were nearly constant. Oxygen demand measured by dark core incubation (12.7-56.9 mmol m–2 d–1 was strongly correlated with water temperature. Rates agreed reasonably well with diffusive oxygen fluxes calculated from microprofiles while ammonium and phosphorus regeneration rates predicted from porewater gradients (-309.3-43.4 and -0.1-0.7 μmol m–2 d–1, respectively were significantly lower than rates measured via core incubations (-129.8-5420.5 and -120.4-35.4 μmol m–2 d–1, respectively. This is a probable consequence of insufficient vertical resolution of nutrient profiles and lack of steady state conditions. A sediment resuspension experiment, carried out under controlled laboratory conditions, indicated large instantaneous oxygen and nitrate consumption, a transient increase of denitrification rates and the rapid release of ammonium and soluble reactive phosphorus. In unconsolidated sediments, resuspension and mixing of sediment particles are key processes regulating mineralisation rates and benthic-pelagic coupling.

  13. Holocene Deep Ocean Variability Detected with Individual Benthic Foraminifera

    Science.gov (United States)

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

    2015-12-01

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

  14. Multivariate benthic ecosystem functioning in the Arctic – benthic fluxes explained by environmental parameters in the southeastern Beaufort Sea

    Directory of Open Access Journals (Sweden)

    H. Link

    2013-09-01

    Full Text Available The effects of climate change on Arctic marine ecosystems and their biogeochemical cycles are difficult to predict given the complex physical, biological and chemical interactions among the ecosystem components. We studied benthic biogeochemical fluxes in the Arctic and the influence of short-term (seasonal to annual, long-term (annual to decadal and other environmental variability on their spatial distribution to provide a baseline for estimates of the impact of future changes. In summer 2009, we measured fluxes of dissolved oxygen, nitrate, nitrite, ammonia, soluble reactive phosphate and silicic acid at the sediment–water interface at eight sites in the southeastern Beaufort Sea at water depths from 45 to 580 m. The spatial pattern of the measured benthic boundary fluxes was heterogeneous. Multivariate analysis of flux data showed that no single or reduced combination of fluxes could explain the majority of spatial variation, indicating that oxygen flux is not representative of other nutrient sink–source dynamics. We tested the influence of eight environmental parameters on single benthic fluxes. Short-term environmental parameters (sinking flux of particulate organic carbon above the bottom, sediment surface Chl a were most important for explaining oxygen, ammonium and nitrate fluxes. Long-term parameters (porosity, surface manganese and iron concentration, bottom water oxygen concentrations together with δ13Corg signature explained most of the spatial variation in phosphate, nitrate and nitrite fluxes. Variation in pigments at the sediment surface was most important to explain variation in fluxes of silicic acid. In a model including all fluxes synchronously, the overall spatial distribution could be best explained (57% by the combination of sediment Chl a, phaeopigments, δ13Corg, surficial manganese and bottom water oxygen concentration. We conclude that it is necessary to consider long-term environmental variability along with

  15. Phototoxicity of TiO{sub 2} nanoparticles to a freshwater benthic amphipod: Are benthic systems at risk?

    Energy Technology Data Exchange (ETDEWEB)

    Li, Shibin, E-mail: li.shibin@epa.gov [U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN (United States); Wallis, Lindsay K.; Ma, Hongbo [U.S. Environmental Protection Agency, Office of Research and Development, National Health and Environmental Effects Research Laboratory, Mid-Continent Ecology Division, Duluth, MN (United States); Diamond, Stephen A. [Nanosafe Inc., Blacksburg, VA (United States)

    2014-01-01

    This study investigated phototoxicity of TiO{sub 2} nanoparticles (nano-TiO{sub 2}) to a freshwater benthic amphipod (Hyalella azteca) using 48-h and 96-h bioassays. Thorough monitoring of particle interactions with exposure media (Lake Superior water, LSW) and the surface of organisms was performed using dynamic light scattering, UV/Vis spectroscopy, and Scanning Electron Microscopy. Large agglomeration and sedimentation (> 77%) in LSW was observed after 0.5 h. A simulated solar radiation (SSR)-favored surface attachment of nanoparticles was observed, indicating enhanced phototoxicity with the increased attachment. A 96-h median lethal concentration (LC50) of 29.9 mg/L in H. azteca was calculated, with a daily 4-h UV exposure of 2.2 W/m{sup 2}. Phototoxicity of nano-TiO{sub 2} under SSR had a 21-fold increase as compared to that under ambient laboratory light. This phototoxicity was also dependent on UV dose, with calculated LC50s around 22.9 (95% CI, 20.5–23.3) Wh/m{sup 2} when exposed to 20 mg/L nano-TiO{sub 2}. Also, H. azteca exhibited negative phototaxis in the presence of shelters, indicating that other factors might play a role in environmental systems. Finally, the environmental implications of nano-TiO{sub 2} to benthic organisms were illustrated, emphasizing the importance of various environmental factors in the ultimate phototoxicity. This increased phototoxicity and its complex interactions with various environmental factors suggest further investigations are needed for future risk assessment of photoactive nanomaterials to benthic organisms. - Graphical abstract: Display Omitted - Highlights: •Large aggregation of TiO{sub 2} nanoparticles in Lake Superior water was observed. •Phototoxicity was dependent on the dose of both solar radiation and nanoparticle. •A solar radiation favored surface attachment of nanoparticles was observed. •Hyalella azteca exhibited negative phototaxis in the presence of shelters. •Factors influencing

  16. Generalized Fibonacci zone plates

    CERN Document Server

    Ke, Jie; Zhu, Jianqiang

    2015-01-01

    We propose a family of zone plates which are produced by the generalized Fibonacci sequences and their axial focusing properties are analyzed in detail. Compared with traditional Fresnel zone plates, the generalized Fibonacci zone plates present two axial foci with equal intensity. Besides, we propose an approach to adjust the axial locations of the two foci by means of different optical path difference, and further give the deterministic ratio of the two focal distances which attributes to their own generalized Fibonacci sequences. The generalized Fibonacci zone plates may allow for new applications in micro and nanophotonics.

  17. Aspects of benthic decapod diversity and distribution from rocky nearshore habitat at geographically widely dispersed sites.

    Directory of Open Access Journals (Sweden)

    Gerhard Pohle

    Full Text Available Relationships of diversity, distribution and abundance of benthic decapods in intertidal and shallow subtidal waters to 10 m depth are explored based on data obtained using a standardized protocol of globally-distributed samples. Results indicate that decapod species richness overall is low within the nearshore, typically ranging from one to six taxa per site (mean = 4.5. Regionally the Gulf of Alaska decapod crustacean community structure was distinguishable by depth, multivariate analysis indicating increasing change with depth, where assemblages of the high and mid tide, low tide and 1 m, and 5 and 10 m strata formed three distinct groups. Univariate analysis showed species richness increasing from the high intertidal zone to 1 m subtidally, with distinct depth preferences among the 23 species. A similar depth trend but with peak richness at 5 m was observed when all global data were combined. Analysis of latitudinal trends, confined by data limitations, was equivocal on a global scale. While significant latitudinal differences existed in community structure among ecoregions, a semi-linear trend in changing community structure from the Arctic to lower latitudes did not hold when including tropical results. Among boreal regions the Canadian Atlantic was relatively species poor compared to the Gulf of Alaska, whereas the Caribbean and Sea of Japan appeared to be species hot spots. While species poor, samples from the Canadian Atlantic were the most diverse at the higher infraordinal level. Linking 11 environmental variables available for all sites to the best fit family-based biotic pattern showed a significant relationship, with the single best explanatory variable being the level of organic pollution and the best combination overall being organic pollution and primary productivity. While data limitations restrict conclusions in a global context, results are seen as a first-cut contribution useful in generating discussion and more in

  18. Impact of flow conditions on ammonium uptake and microbial community structure in benthic biofilms

    Science.gov (United States)

    Arnon, Shai; Yanuka, Keren; Nejidat, Ali

    2010-05-01

    Excess nitrogen in surface waters is widely recognized to be a major global problem that adversely affects ecosystems, human health, and the economy. Today, most efforts to understand and model nutrient dynamics at large scales relies on macro-scale parameterization, such as mean channel geometry and velocity with uniform flow assumptions, as well as gross averages of in-situ nutrient transformation rates. However, there is increasing evidence that nutrient transformations in hyporheic zone are regulated by coupling between physical, chemical, and microbiological processes. Ignoring this greatly hinders the estimation of average biochemical transformation rates under the variable flow conditions found in aquatic systems. We used a combination of macro- and micro-scale observations in laboratory flumes to show that interplay between hydrodynamic transport, redox gradients, and microbial metabolism controls ammonium utilization by hyporheic microbial communities. Biofilm structural characteristics were quantified using denaturing gradient gel electrophoresis (DGGE) and real time PCR, while redox and pH gradients were measured using microelectrodes. We found that overlying velocities had profound effect on ammonium uptake due to mass transfer of ammonium from the bulk water to the benthic biofilms, but also due to the delivery of oxygen into the sediment bed. Under laminar flow conditions we didn't observe any change of ammonium uptake as a response to increase in overlying velocity. However, under non-laminar conditions we observe monotonic increase in ammonium uptake, with the greatest uptake under the fastest flow condition. We will discuss ammonium uptake rates results in the context of the different microbial communities and the micro-scale observations that were obtained using the microelectrodes. We anticipate that combined knowledge of the response of the microbial community and bulk nitrogen utilization rates to flow conditions will support the development of

  19. Benthic Foraminifera along a depth transect in western Bahrain: seasonal variations and environmental assessment

    Science.gov (United States)

    Muhammad, Arslan; Kaminski, Michael; Tawabini, Bassam; Ramadan, Khalid Al; Babalola, Lamidi; Frontalini, Fabrizio

    2015-04-01

    We surveyed living benthic foraminifera in a depth transect off western Bahrain (Arabian Gulf) with the aim of understanding the seasonal population dynamics and environmental parameters. In winter, the population was found to be highest due to the large number of rotaliids, followed by miliolids. In each season, the population was found to increase along the depth transect due to the higher number of juveniles. A strong correlation is observed between foraminiferal population and sediment grain size - the juveniles are most abundant on coarser-sandy substrate. The population decreases in the spring and is lowest in the summer. Finally, the living population recovered again in the autumn with increasing juveniles/adult ratios along the depth transect. Results of species consistency and relative abundance showed that Ammonia was consistent from the shallowest to the deepest station, whereas miliolids started appearing in the deeper stations. The average numbers of Elphidium and Peneroplis also increased along the depth transect. Another seasonal effect is that juveniles of Ammonia tepida are found during each season reflecting its reproduction throughout the year, whereas Brizalina pacifica was only found during spring and autumn. The study of environmental parameters reveals that the site is subjected to eutrophication i.e. nitrates and sulfates, however, pollution by heavy metals and hydrocarbons is not significant. An assessment of 63 heavy metals in sediment samples showed that none of the metals had concentrations higher than the internationally accepted norms, which is further confirmed by values of the Foraminiferal Deformities Index of less than 2%. Likewise, no hydrocarbons were detected in the water or sediment samples. Therefore, it is concluded that the site in Bahrain is not yet adversely affected by human development, and therefore can provide baseline information for future comparison and assessment of foraminiferal assemblages in contaminated zones

  20. How to react to shallow water hydrodynamics: The larger benthic foraminifera solution

    Science.gov (United States)

    Briguglio, Antonino; Hohenegger, Johann

    2016-01-01

    Symbiont-bearing larger benthic foraminifera inhabit the photic zone to provide their endosymbiotic algae with light. Because of the hydrodynamic conditions of shallow water environments, tests of larger foraminifera can be entrained and transported by water motion. To resist water motion, these foraminifera have to build a test able to avoid transport or have to develop special mechanisms to attach themselves to substrate or to hide their test below sediment grains. For those species which resist transport by the construction of hydrodynamic convenient shapes, the calculation of hydrodynamic parameters of their test defines the energetic input they can resist and therefore the scenario where they can live in. Measuring the density, size and shape of every test, combined with experimental data, helps to define the best mathematical approach for the settling velocity and Reynolds number of every shell. The comparison between water motion at the sediment-water interface and the specimen-specific settling velocity helps to calculate the water depths at which, for a certain test type, transport, deposition and accumulation may occur. The results obtained for the investigated taxa show that the mathematical approach gives reliable results and can discriminate the hydrodynamic behaviour of different shapes. Furthermore, the study of the settling velocities, calculated for all the investigated taxa, shows that several species are capable to resist water motion and therefore they appear to be functionally adapted to the hydrodynamic condition of its specific environment. The same study is not recommended on species which resist water motion by adopting hiding or anchoring strategies to avoid the effect of water motion.

  1. The reciprocity between coiling direction and dimorphic reproduction in benthic foraminifera

    Digital Repository Service at National Institute of Oceanography (India)

    Nigam, R.; Khare, N.

    , an attempt is made to study the relationship between mode of reproduction (sexual/asexual) and coiling direction (dextral / sinistral) in the benthic foraminiferal species Rotalidium annectens (Parker and Jones). Proloculus (initial chamber) size is taken...

  2. Relationship between abundance and morphology of benthic foraminifera Epistominella exigua: Palaeoclimatic implications

    Digital Repository Service at National Institute of Oceanography (India)

    Saraswat, R.; Deopujari, A; Nigam, R.; Henriques, P.J.

    The relationship between abundance (relative as well as absolute abundance) and morphology (size of the shell, numbers and proloculus size) of benthic foraminifera Epistominella exigua has been studied in a core to understand the influence...

  3. Benthic Exchange of Biogenic Elements in the Estuarine and Nearshore Waters of Western India

    Digital Repository Service at National Institute of Oceanography (India)

    Pratihary, A.K.

    by a series of laboratory based incubation experiments mimicking the natural physical condition of the estuary. Nutrient enrichment experiments were carried out at these sites to understand the coupling between benthic inputs and ecosystem productivity...

  4. NOAA Office for Coastal Management Benthic Habitat Data, Bogue Sound, North Carolina, 1992 (NODC Accession 0089465)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are benthic study GIS shapefiles (.shp, .shx, .prj) with associated .dbf attribute tables and specific Federal Geographic Data Committee metadata. A...

  5. Coastal Bend Texas Benthic Habitat - San Antonio Bay (NODC Accession 0070784)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Coastal Services Center purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic habitat...

  6. Coastal Bend Texas Benthic Habitat - Lower Laguna Madre (NODC Accession 0070784)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Coastal Services Center purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic habitat...

  7. Coastal Bend Texas Benthic Habitat - Espiritu Santo Bay (NODC Accession 0070784)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Coastal Services Center purchased services to process existing and new digital multi-spectral imagery and create digital benthic habitat...

  8. Shallow-Water Benthic Habitats of Southwest Puerto Rico: GeoEye Image po_1700252_PS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of two areas in Southwest Puerto Rico (PR), including the Guanica Bay/La Parguera...

  9. Guam Community Coral Reef Monitoring Program, Benthic Training Surveys at Guam in 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Guam community members gathered benthic cover data using a 0.25m2 quadrat with 6 intersecting points at each meter along a 25-meter transect. Members identified...

  10. NOAA Office for Coastal Management Benthic Habitat Data, coastal Massachusetts, 1994-1996 (NODC Accession 0089463)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are benthic study GIS shapefiles (.shp, .shx, .prj) with associated .dbf attribute tables and specific Federal Geographic Data Committee metadata. A...

  11. Shallow-Water Benthic Habitats of Southwest Puerto Rico: Ground Validation Site Locations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of two areas in Southwest Puerto Rico (PR), including the Guanica Bay/La Parguera...

  12. NOAA Office for Coastal Management Benthic Habitat Data, Humboldt Bay, CA, 2009 (NODC Accession 0090251)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are benthic study GIS shapefiles (.shp, .shx, .prj) with associated .dbf attribute tables and specific Federal Geographic Data Committee metadata. A...

  13. Coastal Bend Texas Benthic Habitat Mapping Corpus Christi Bay 2004 Biotic

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  14. Surface meteorological conditions at benthic disturbance experiment site - INDEX area during austral winter 1997

    Digital Repository Service at National Institute of Oceanography (India)

    Suryanarayana, A.; Murty, V.S.N.; RameshBabu, V.; Beena, B.S.

    Benthic Disturbance Experiment surveys in the Central Indian Ocean Basin yielded baseline data on surface meteorological conditions during June and August, 1997 together with sea surface temperature (SST) and could data to estimate the air-sea heat...

  15. Baseline assessment of benthic communities of the Flower Garden Banks (2010 - present): 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The proposed work develop baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys will...

  16. Benthic disturbance and monitoring experiment in the Central Indian Ocean Basin

    Digital Repository Service at National Institute of Oceanography (India)

    Sharma, R.; Nath, B.N.

    Environmental impact assessment studies for deep-sea manganese nodule mining have been initiated in the Central indian Ocean Basin since 1995. As a part of the first phase for collecting the benthic baseline data, echosounding, subbottom profiling...

  17. Sediment redistribution during simulated benthic disturbance and its implications on deep seabed mining

    Digital Repository Service at National Institute of Oceanography (India)

    Sharma, R.; Nath, B.N.; Parthiban, G.; Sankar, S.J.

    A benthic disturbance experiment was conducted in the Central Indian Basin to evaluate the possible effects of sediment redistribution on marine ecosystem during deep-sea mining. The analyses of disturbance features on the seafloor and particle...

  18. Marine Benthic Invertebrates in Mamala Bay, Oahu, Hawaii 1994 (NODC Accession 9900151)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Planktonic larval stages of many benthic marine invertebrates are especially susceptible to environmental stress, such as the presence of pollution. Recruitment of...

  19. CRED Integrated Benthic Habitat Map for French Frigate Shoals, Northwestern Hawaiian Islands 2007

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is an integrated benthic habitat map system which consists of a number of separate map layers including multibeam bathymetry, acoustic backscatter imagery,...

  20. CRED Integrated Benthic Habitat Map for Tutuila Island, American Samoa Year 2007

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This is an integrated benthic habitat map system which consists of a number of separate map layers including multibeam bathymetry, digital NOAA nautical charts,...

  1. Oxygen respiration rates of benthic foraminifera as measured with oxygen microsensors

    DEFF Research Database (Denmark)

    Geslin, E.; Risgaard-Petersen, N.; Lombard, Fabien;

    2011-01-01

    of the foraminiferal specimens. The results show a wide range of oxygen respiration rates for the different species (from 0.09 to 5.27 nl cell−1 h−1) and a clear correlation with foraminiferal biovolume showed by the power law relationship: R = 3.98 10−3 BioVol0.88 where the oxygen respiration rate......Oxygen respiration rates of benthic foraminifera are still badly known, mainly because they are difficult to measure. Oxygen respiration rates of seventeen species of benthic foraminifera were measured using microelectrodes and calculated on the basis of the oxygen fluxes measured in the vicinity...... other microbenthos groups (nematodes, copepods, ostracods, ciliates and flagellates) suggests that benthic foraminifera have a lower oxygen respiration rates per unit biovolume. The total contribution of benthic foraminifera to the aerobic mineralisation of organic matter is estimated for the studied...

  2. Vieques, Puerto Rico Benthic Habitat Maps derived from 2006-2008 IKONOS imagery and orthophotography

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic habitat maps of the nearshore marine environment of Vieques, Puerto Rico were created by visual interpretation of remotely sensed imagery. The objective of...

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

    Science.gov (United States)

    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...

  4. NOAA Office for Coastal Management Benthic Habitat Data, Willapa Bay, Washington, 1995 (NODC Accession 0089466)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — These data are benthic study GIS shapefiles (.shp, .shx, .prj) with associated .dbf attribute tables and specific Federal Geographic Data Committee metadata. A...

  5. Examination of Algal Diversity and Benthic Community Structure at Palmyra Atoll, U.S. Line Islands

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — Palmyra Atoll National Wildlife Refuge is the second largest atoll under U.S. jurisdiction in the Pacific Ocean. Until recently, little was known about benthic...

  6. NANPHAB -- Benthic Habitat polygons for North Anacapa Passage (UTM 10N, NAD83)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Benthic habitat polygon coverages have been created for marine reserve locations surrounding the Santa Barbara Basin. Diver, ROV and submersible video transects,...

  7. AFSC/RACE/GAP/Yeung: Eastern Bering Sea Essential Fish Habitat Benthic Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic samples were collected between 2009-2012 in the Bering Sea to study Essential Fish Habitat. Station locations were at or near fixed stations of the AFSC...

  8. Coastal Bend Texas Benthic Habitat Mapping Corpus Christi Bay 2004 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  9. Integrated ecosystem assessment of Vieques, Puerto Rico Benthic Composition Assessment and Monitoring Data

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This fish and benthic composition database is the result of a multifaceted effort described below.The National Oceanic and Atmospheric Administration's (NOAA)...

  10. Integrated ecosystem assessment of Vieques, Puerto Rico Benthic Composition Assessment and Monitoring Data (NODC Accession 0125235)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This fish and benthic composition database is the result of a multifaceted effort described below. The National Oceanic and Atmospheric Administration's (NOAA)...

  11. Baseline assessment of fish and benthic communities of the Flower Garden Banks

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The work developed baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys employed diving,...

  12. Coastal Bend Texas Benthic Habitat Mapping Upper Laguna Madre Bay 2004 Substrate

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  13. Coastal Bend Texas Benthic Habitat Mapping Reprocessed DOQQ Aerial Imagery (NODC Accession 0086051)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Coastal Services Center purchased services to reprocess existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  14. Coastal Bend Texas Benthic Habitat Mapping Corpus Christi Bay 2004 Geodatabase

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  15. Coastal Bend Texas Benthic Habitat Mapping Patchy Shapefile Map - Lower Laguna Madre (NODC Accession 0070784)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Coastal Services Center (CSC) requested the creation of benthic habitat data along the southern Texas coast to support the Texas Seagrass Monitoring...

  16. Coastal Bend Texas Benthic Habitat Mapping Patchy Shapefile Map - San Antonio Bay and Espiritu Santo Bay

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Office for Coastal Management (OCM) requested the creation of benthic habitat data along the southern Texas coast to support the Texas Seagrass Monitoring...

  17. Coastal Bend Texas Benthic Habitat Mapping Corpus Christi Bay 2004 Geoform

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

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

    Science.gov (United States)

    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,...

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

    Science.gov (United States)

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

  20. Shallow-Water Benthic Habitats of Southwest Puerto Rico: GeoEye Image po_483895_PS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of two areas in Southwest Puerto Rico (PR), including the Guanica Bay/La Parguera...

  1. Shallow-Water Benthic Habitats of Southwest Puerto Rico: GeoEye Image po_0072610_PS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of two areas in Southwest Puerto Rico (PR), including the Guanica Bay/La Parguera...

  2. Effects of hydraulic shellfish harvesting on benthic communities and sediment chemistry 2009-2013

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The effects of hydraulic shellfish harvesting on the ecology of biological communities and chemistry of benthic sediments were investigated through a series of...

  3. Pacific Remote Islands MNM: Initial Survey Instructions for Benthic Marine Cryptobiota

    Data.gov (United States)

    US Fish and Wildlife Service, Department of the Interior — The purpose of the survey is to expand knowledge of the biodiversity of benthic marine invertebrates that are poorly known and are generally not identified in more...

  4. Shallow-Water Benthic Habitats of Southwest Puerto Rico: GeoEye Image po_502736_PS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of two areas in Southwest Puerto Rico (PR), including the Guanica Bay/La Parguera...

  5. Baseline assessment of fish and benthic communities of the Flower Garden Banks (NODC Accession 0118358)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The proposed work develop baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys will...

  6. Baseline assessment of the benthic communities of the Flower Garden Banks

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The work developed baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys employed diving,...

  7. Baseline assessment of the fish and benthic communities of the Flower Garden Banks (NODC Accession 0118358)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The proposed work develop baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys will...

  8. Coastal Bend Texas Benthic Habitat Mapping Patchy Shapefile Map - Lower Laguna Madre

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The NOAA Office for Coastal Management (OCM) requested the creation of benthic habitat data along the southern Texas coast to support the Texas Seagrass Monitoring...

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

    Science.gov (United States)

    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 ...

  10. St. Croix, USVI Benthic Composition Assessment and Monitoring Data (2002 - Present)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This fish and benthic composition database is the result of a multifaceted effort described below. The intent of this work is five fold: 1) To spatially...

  11. La Parguera, Puerto Rico Benthic Composition Assessment and Monitoring Data (2002 - Present)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This fish and benthic composition database is the result of a multifaceted effort described below. The intent of this work is five fold: 1) To spatially...

  12. St. John, USVI Benthic Composition Assessment and Monitoring Data (2002 - Present)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This fish and benthic composition database is the result of a multifaceted effort described below.The intent of this work is five fold: 1) To spatially characterize...

  13. Coastal Bend Texas Benthic Habitat Mapping Upper Laguna Madre Bay 2004 Geodatabase

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Office for Coastal Management purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic...

  14. Coastal Bend Texas Benthic Habitat Mapping Baffin Bay (NODC Accession 0070784)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — In 2006 and 2007 the NOAA Coastal Services Center purchased services to process existing digital multi-spectral imagery (ADS-40) and create digital benthic habitat...

  15. Shallow-Water Benthic Habitats of Southwest Puerto Rico: Accuracy Assessment Site Locations

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of two areas in Southwest Puerto Rico (PR), including the Guanica Bay/La Parguera...

  16. Shallow-Water Benthic Habitats of Southwest Puerto Rico: GeoEye Image po_0900172_PS

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Shallow-water (<30m) benthic habitat maps of the nearshore marine environment of two areas in Southwest Puerto Rico (PR), including the Guanica Bay/La Parguera...

  17. Kailua Bay, Oahu, Hawaii Benthic Mapping Data 1999-2001 (NODC Accession 0001239)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic mapping surveys were conducted from March 1999 to January 2001 aperiodically in support of research related to sedimentology, sea level history, and reef...

  18. SANAHAB -- Benthic Habitat polygons for South Anacapa Island (UTM 10N, NAD83)

    Data.gov (United States)

    U.S. Geological Survey, Department of the Interior — Benthic habitat polygon coverages have been created for marine reserve locations surrounding the Santa Barbara Basin. Diver, ROV and submersible video transects,...

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

    Science.gov (United States)

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

  20. Sediment distribution and dynamics inferred by integrated electromagnetic, optical and acoustic benthic profiling in the western Bay of Plenty (New Zealand)

    Science.gov (United States)

    Kulgemeyer, T.; von Dobeneck, T. F.; Müller, H.; Bryan, K. R.; de Lange, W. P.; Battershill, C.

    2015-12-01

    In October 2011, New Zealand experienced a marine pollution disaster after the MV RENA ran aground in the western Bay of Plenty. To estimate the transport and burial potential of contaminants, local sediment distribution and dynamics had to be assessed quickly. Our study made use of the benthic profiler NERIDIS III of the University of Bremen. 33 cross-shore profiles, each ca. 8 km long, have been surveyed. The main instrument is a controlled-source electromagnetic (CSEM) sensor, which is measuring the electric conductivity and magnetic susceptibility of the seafloor. High-resolution, overlapping seafloor photos have been taken by a bow-mounted digital camera. An on-board CTD with turbidity sensor complete the sensor arrangement. From the EM data, porosity and magnetite concentrations have been calculated and interpolated. The resulting maps show specific zones of magnetite enrichment, higher concentrations are correlated to low porosity. Photos have been used along with acoustic backscatter measured by a sidescan sonar to sketch out a preliminary map of sediment facies. Based on this, sides for grab sampling were selected. By taking grain size and mineralogy into account, a detailed map of the regional lithofacies could be created. Local sediment dynamics have been inferred by the observation of bedforms, the turbidity of bottom water and lithofacies. The results show two anti-parallel longshore transport paths dependent on differing weather conditions and water depths. The longshore magnetite distribution indicates that the heavy mineral fraction is mainly affected by storm-induced sediment transport. Our study demonstrates how integrated benthic profiling adds to the interpretability of data obtained by established methods. By bridging the gap between area-covering, but indirect data from hydroacoustics and precise, but punctual data from samples, benthic profiling enables fast and detailed assessment of sediment distribution and dynamics on a large scale.

  1. Fault zone hydrogeology

    Science.gov (United States)

    Bense, V. F.; Gleeson, T.; Loveless, S. E.; Bour, O.; Scibek, J.

    2013-12-01

    Deformation along faults in the shallow crust (evaluation of the impact of faults to fluid flow patterns remains a challenge and requires a multidisciplinary research effort of structural geologists and hydrogeologists. However, we find that these disciplines often use different methods with little interaction between them. In this review, we document the current multi-disciplinary understanding of fault zone hydrogeology. We discuss surface- and subsurface observations from diverse rock types from unlithified and lithified clastic sediments through to carbonate, crystalline, and volcanic rocks. For each rock type, we evaluate geological deformation mechanisms, hydrogeologic observations and conceptual models of fault zone hydrogeology. Outcrop observations indicate that fault zones commonly have a permeability structure suggesting they should act as complex conduit-barrier systems in which along-fault flow is encouraged and across-fault flow is impeded. Hydrogeological observations of fault zones reported in the literature show a broad qualitative agreement with outcrop-based conceptual models of fault zone hydrogeology. Nevertheless, the specific impact of a particular fault permeability structure on fault zone hydrogeology can only be assessed when the hydrogeological context of the fault zone is considered and not from outcrop observations alone. To gain a more integrated, comprehensive understanding of fault zone hydrogeology, we foresee numerous synergistic opportunities and challenges for the discipline of structural geology and hydrogeology to co-evolve and address remaining challenges by co-locating study areas, sharing approaches and fusing data, developing conceptual models from hydrogeologic data, numerical modeling, and training interdisciplinary scientists.

  2. Benthic microbial communities of coastal terrestrial and ice shelf Antarctic meltwater ponds

    OpenAIRE

    Archer, Stephen D. J.; McDonald, Ian R.; Herbold, Craig W.; Lee, Charles K; Cary, Craig S.

    2015-01-01

    The numerous perennial meltwater ponds distributed throughout Antarctica represent diverse and productive ecosystems central to the ecological functioning of the surrounding ultra oligotrophic environment. The dominant taxa in the pond benthic communities have been well described however, little is known regarding their regional dispersal and local drivers to community structure. The benthic microbial communities of 12 meltwater ponds in the McMurdo Sound of Antarctica were investigated to ex...

  3. Towards Automated Annotation of Benthic Survey Images: Variability of Human Experts and Operational Modes of Automation

    OpenAIRE

    Oscar Beijbom; Edmunds, Peter J.; Chris Roelfsema; Jennifer Smith; Kline, David I.; Neal, Benjamin P.; Matthew J Dunlap; Vincent Moriarty; Tung-Yung Fan; Chih-Jui Tan; Stephen Chan; Tali Treibitz; Anthony Gamst; B. Greg Mitchell; David Kriegman

    2015-01-01

    Global climate change and other anthropogenic stressors have heightened the need to rapidly characterize ecological changes in marine benthic communities across large scales. Digital photography enables rapid collection of survey images to meet this need, but the subsequent image annotation is typically a time consuming, manual task. We investigated the feasibility of using automated point-annotation to expedite cover estimation of the 17 dominant benthic categories from survey-images capture...

  4. The role of zooplankton in the pelagic-benthic coupling of the Southern Ocean

    OpenAIRE

    Schnack-Schiel, Sigrid B.; Isla, Enrique

    2005-01-01

    [EN] Zooplankton contributes in different ways to pelagic-benthic coupling: Their faecal material is a major route of energy flow and the vertical migrations of many species as well as the production of pelagic larvae by benthic organisms represent different paths to link the two subsystems. Antarctic particle fluxes have been shown to be highly variable in size and composition within a given region and even at the same site from year to year. There are also differences throughout the water c...

  5. Modeling food web interactions in benthic deep-sea ecosystems. A practical guide

    OpenAIRE

    Soetaert, K.E.R.; Van Oevelen, D.J.

    2009-01-01

    Deep-sea benthic systems are notoriously difficult to sample. Even more than for other benthic systems, many flows among biological groups cannot be directly measured, and data sets remain incomplete and uncertain. In such cases, mathematical models are often used to quantify unmeasured biological interactions. Here, we show how to use so-called linear inverse models (LIMs) to reconstruct material and energy flows through food webs in which the number of measurements is a fraction of the tota...

  6. Modeling food web interactions in benthic deep-sea ecosystems: a practical guide

    OpenAIRE

    2009-01-01

    Deep-sea benthic systems are notoriously difficult to sample. Even more than for other benthic systems, many flows among biological groups cannot be directly measured, and data sets remain incomplete and uncertain. In such cases, mathematical models are often used to quantify unmeasured biological interactions. Here, we show how to use so-called linear inverse models (LIMs) to reconstruct material and energy flows through food webs in which the number of measurements is a fraction of the tota...

  7. Consequences of increasing hypoxic disturbance on benthic communities and ecosystem functioning.

    Directory of Open Access Journals (Sweden)

    Anna Villnäs

    Full Text Available Disturbance-mediated species loss has prompted research considering how ecosystem functions are changed when biota is impaired. However, there is still limited empirical evidence from natural environments evaluating the direct and indirect (i.e. via biota effects of disturbance on ecosystem functioning. Oxygen deficiency is a widespread threat to coastal and estuarine communities. While the negative impacts of hypoxia on benthic communities are well known, few studies have assessed in situ how benthic communities subjected to different degrees of hypoxic stress alter their contribution to ecosystem functioning. We studied changes in sediment ecosystem function (i.e. oxygen and nutrient fluxes across the sediment water-interface by artificially inducing hypoxia of different durations (0, 3, 7 and 48 days in a subtidal sandy habitat. Benthic chamber incubations were used for measuring responses in sediment oxygen and nutrient fluxes. Changes in benthic species richness, structure and traits were quantified, while stress-induced behavioral changes were documented by observing bivalve reburial rates. The initial change in faunal behavior was followed by non-linear degradation in benthic parameters (abundance, biomass, bioturbation potential, gradually impairing the structural and functional composition of the benthic community. In terms of ecosystem function, the increasing duration of hypoxia altered sediment oxygen consumption and enhanced sediment effluxes of NH(4(+ and dissolved Si. Although effluxes of PO(4(3- were not altered significantly, changes were observed in sediment PO(4(3- sorption capability. The duration of hypoxia (i.e. number of days of stress explained a minor part of the changes in ecosystem function. Instead, the benthic community and disturbance-driven changes within the benthos explained a larger proportion of the variability in sediment oxygen- and nutrient fluxes. Our results emphasize that the level of stress to the

  8. Measurement of benthic nutrient fluxes in mediterranean shellfish farms - a methodological approach

    OpenAIRE

    Grenz, C; Plantecuny, Mr; Plante, R.; Alliot, E; Baudinet, D; Berland, B

    1991-01-01

    Benthic chambers were used to investigate fluctuations in nutrient fluxes and oxygen changes when comparing two benthic biota. Muddy sediments located under mussel-cultivation ropes were compared with a station outside the mussels' influence. Biodeposition from the mussels results in a drastic increase in the nutrient fluxes. A standard procedure is established in order to give reliable comparisons between stations and seasons: as a rule it should include six-hour periods of incubation with s...

  9. Benthic microalgal production in the Arctic: Applied methods and status of the current database

    DEFF Research Database (Denmark)

    Glud, Ronnie Nøhr; Woelfel, Jana; Karsten, Ulf;

    2009-01-01

    The current database on benthic microalgal production in Arctic waters comprises 10 peer-reviewed and three unpublished studies. Here, we compile and discuss these datasets, along with the applied measurement approaches used. The latter is essential for robust comparative analysis and to clarify...... between increased freshwater run-off, shrinking sea-ice cover, light availability and benthic primary production to assess future impact on the Arctic food web and trophic coupling....

  10. Messinian paleoenvironmental evolution in the lower Guadalquivir Basin (SW Spain) based on benthic foraminifera.

    OpenAIRE

    Pérez-Asensio, J.N.; Aguirre, J.; Schmiedl, G.; Civis Llovera, J.

    2012-01-01

    Benthic foraminiferal assemblages of a drill core from the lower Guadalquivir Basin (northern Gulf of Cádiz, SW Spain) have been analyzed in order to reconstruct the paleoenvironmental evolution in the vicinity of the Betic seaways during the Messinian. The core consists of marine sediments ranging from the latest Tortonian to the early Pliocene. Changes in the abundance of certain marker species, planktonic/benthic ratio (P/B ratio), paleodepth estimated with a transfer function, content of ...

  11. The role of bio-hydrodynamic interactions in determining the functioning of shallow, benthic ecosystems

    OpenAIRE

    Morris, Edward P; Peralta, Gloria; Brun, Fernando G.; Bouma, Tjeerd J.; Hendriks, Iris E; Benavente, Javier; Lara, Miguel; González-Ortiz, Vanesa; Van Engeland, Tom; Van Duren, Luca A.; Perez-Llorens, J. Lucas

    2011-01-01

    Epi-benthic organisms play a strong role in controlling pelagic-benthic mass transfer rates by directly modifying concentration gradients (i.e., production, or removal of material) and by indirectly modifying near-bed hydrodynamics. Focusing on these bio-hydrodynamic interactions, we will demonstrate how the physical structure of different assemblages, via their interaction with currents and waves, results in spatio-temporal variation in transfer rates at a range of scales. Examples will be u...

  12. Seasonal Abundance of Benthic Communities in Coral Areas of Karah Island, Terengganu, Malaysia

    OpenAIRE

    Ibrahim*(1), Sakri; Hussin(1), Wan Mohd Rauhan Wan; Kassim(1), Zaleha; Joni(1), Zuliatini Mohamad; Zakaria(1), Mohamad Zaidi; Hajisamae, Sukree

    2006-01-01

    Benthic communities are important to marine ecosystem and form important food source for most marine organisms especially fish. Study of this biota is important as it could be an indicator to overall aquatic productivity. Benthic communities in Karah Island, Terengganu, Malaysia were studied to find their relationship with different monsoon seasons and types of substrate. Surveys were conducted 4 times; two times each during pre-monsoon phase (September - October) and post-monsoon phase (Apri...

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

    Science.gov (United States)

    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

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

    Directory of Open Access Journals (Sweden)

    Andreas F Haas

    Full Text Available 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

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

    OpenAIRE

    P. Stief

    2013-01-01

    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) e...

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

    OpenAIRE

    P. Stief

    2013-01-01

    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 ecosys...

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

    Science.gov (United States)

    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

  18. Tolerance of benthic foraminifera to anthropogenic stressors from three sites of the Egyptian coasts

    OpenAIRE

    Amani Badawi; Wafaa El-Menhawey

    2016-01-01

    Surely the coupling of natural and anthropogenic stressors combined with a lack of regulation resulted in the current threat to a large part of coastal marine biodiversity as well as coastal human societies, particularly in highly populated regions. The distribution pattern of benthic foraminifera as sensitive bio-indicator is utilized to assess human-induced impact on the coastal area, at Alexandria, Port Said and Suez cites of Egypt. Twenty-two benthic foraminiferal genera were identified a...

  19. Effect of seaweed proliferation on benthic habitat quality assessed by Sediment Profile Imaging

    Science.gov (United States)

    Bona, Francesca

    2006-10-01

    Changes in sediment quality, with special reference to benthic habitat conditions resulting from macroalgae overgrowth, were studied in the Venice Lagoon, Italy. Data were collected biweekly in spring and summer from 1993 to 1998 and from 2001 to 2002, as part of the macroalgae growth control strategies managed by the Venice Water Authority-Consorzio Venezia Nuova. Benthic habitat conditions were studied by means of Sediment Profile Imaging, which allowed the collection of several variables: aRPD (apparent redox potential discontinuity), prism penetration depth, presence of anoxia on the surface of the sediment, presence of reduced gas bubbles, stage of benthic colonization. All these variables led to the calculation of an environmental index (Organism-Sediment Index, OSI), which was then related to physical variables and macroalgae abundance. Until 1996, the overall benthic habitat of the Venice Lagoon showed almost stressed conditions; from 1997, the seaweed biomass rapidly declined and the OSI increased significantly. The OSI seemed to be affected by seaweed biomass, sediment compactness and water depth. Macroalgae biomass greater than 4.5 kg/m 2 led to the complete disappearance of stage III of benthic colonization; values as low as 0.70 kg m 2 already had a severe impact on recolonization. SPI attributes indicated the main mechanisms that could have contributed to the benthic quality: seaweed proliferation is often followed by rapid decay of macroalgae biomass, especially when present in large amounts. The decrease in seaweed biomass often results in oxygen depletion in the water column and thus in the sediment, preventing complete benthic colonization. This research confirms the importance of in situ rapid reconnaissance surveys to assess the impact of eutrophication on the benthic habitat.

  20. Benthic-Pelagic coupling in the Black Sea - A model Study

    OpenAIRE

    Capet, Arthur; MEYSMAN, Filip; Soetaert, Karline

    2013-01-01

    While benthic and sediment processes are now recognized as major components of the shelf iogeochemical budget, their representation in 3D biogeochemical model has for long been oversimplified [Soetaert et al., 2000]. These oversimplified formulations of the bottom boundary onditions prevent to account for the response of diagenetic processes to the environment. The onsequent absence of spatial and temporal variability of benthic/pelagic fluxes may lead to mis- valuation of important terms ...

  1. Feeding habit and mode of living of benthic organisms, in relation to the radioecology

    International Nuclear Information System (INIS)

    The type of feeding habit, size spectrum (megalo-, macro-, meio-, and micro-benthos), life form (epi-, and endo-biose) and other modes of living of benthic organisms on and within the bottom sediments are briefly mentioned. Knowledge hitherto obtained concerning radio-ecology is also briefly reviewed in relation to those items mentioned above. Special attention is given to the relationship between the stratification and the mixing of bottom deposits, and the reworking and feeding activities of benthic animals. (auth.)

  2. The benthic macrofauna along the estuarine gradient of the Schelde estuary

    OpenAIRE

    Ysebaert, T.J.; P. Meire; Maes, D.; Buijs, J.

    1993-01-01

    The intertidal benthic macrofauna of the Schelde estuary (The Netherlands and Belgium) was sampled in late autumn of 1990 at 50 stations along the whole salinity gradient (between Vlissingen and Dendermonde), including the freshwater tidal part. All stations were situated in sheltered areas with a relatively muddy sediment. Species richness, diversity and total biomass of the benthic macrofauna decreased along the salinity gradient from Vlissingen to Dendermonde, while total density showed no...

  3. A study on the biodiversity of benthic invertebrates in the waters of Seogwipo, Jeju Island, Korea

    OpenAIRE

    In-Young Cho; Dong-Won Kang; Jisoon Kang; Hosung Hwang; Jeong-Hye Won; Woon Kee Paek; Su-Yuan Seo

    2014-01-01

    The biodiversity of benthic invertebrates in the intertidal and subtidal regions of Gapado, Beomseom, and Munseom islets was surveyed twice in May and September 2013 to study the state of biodiversity in Seogwipo, Jeju Island. As a result, a total of 77 species, 46 families, 25 orders, 14 classes, and nine phyla of benthic invertebrates were found. The species which were found, by taxon, consisted of the following: 26 species of Cnidaria (34%), 24 species of Mollusca (31%), seven species of C...

  4. Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

    Indian Academy of Sciences (India)

    M Manasa; Rajeev Saraswat; Rajiv Nigam

    2016-04-01

    Temporal changes in benthic foraminiferal morpho-groups were suggested as an effective proxy to reconstructpast monsoon intensity from the Arabian Sea. Here, in order to test the applicability of temporalvariation in morpho-groups to reconstruct past monsoon intensity from the Bay of Bengal, we havedocumented recent benthic foraminiferal distribution from the continental shelf region of the northwesternBay of Bengal. Based on the external morphology, benthic foraminifera were categorized intorounded symmetrical (RSBF) and angular asymmetrical benthic foraminifera (AABF). Additionally, afew other dominant groups were also identified based on test composition (agglutinated, calcareous) andabundance (Asterorotalids and Nonions). The relative abundance of each group was compared with theambient physico-chemical conditions, including dissolved oxygen, organic matter, salinity and temperature.We report that the RSBF are abundant in comparatively warm and well oxygenated waters of lowsalinity, suggesting a preference for high energy environment, whereas AABF dominate relatively cold,hypersaline deeper waters with low dissolved oxygen, indicating a low energy environment. The agglutinatedforaminifera, Asterorotalids and Nonions dominate shallow water, low salinity regions, whereasthe calcareous benthic foraminiferal abundance increases away from the riverine influx regions. Foodavailability, as estimated from organic carbon abundance in sediments, has comparatively less influenceon faunal distribution in the northwestern Bay of Bengal, as compared to dissolved oxygen, temperatureand salinity. We conclude that the factors associated with freshwater influx affect the distributionof benthic foraminiferal morpho-groups in the northwestern Bay of Bengal and thus it can be used toreconstruct past monsoon intensity from the Bay of Bengal.

  5. Ensamble de crustáceos bentónicos en un lago salino tropical Benthic crustaceans assemblage in a tropical, saline lake

    Directory of Open Access Journals (Sweden)

    Ma. del Carmen Hernández

    2010-10-01

    (Hyalella azteca, 1 isopod (Caecidotea williamsi and 2 ostracods (Limnocythere inopinata and Candona sp.. Compared to other tropical lakes the species richness is low. It is worth mentioning the high endemism found in the benthic crustaceans' assemblage of Lake Alchichica exemplified by C. williamsi, a new and recently described endemic species; additionally, it is to be expected that both, Candona as H. azteca are also new and endemic species of the lake. The benthic crustaceans were distributed from the coastal zone to the deepest part of the lake (62m displaying variable abundances and taxonomic richness. The ostracodes were the most common crustaceans collected in the littoral zone, in the slope and in the deep zone where no other species were found. Amphipods were the second most abundant group in the coastal zone and in the slope being absent from the deep zone. Isopods are associated exclusively with the tufa deposits, a characteristic habitat of the lake that runs along the slope, so that traditional sampling techniques like those used in this study were unable to collect them. The crustacean assemblage is predominantly composed by species with direct development of diverse trophic positions including herbivores (H. azteca, omnivores (C. williamsi and bacterivores (L. inopinata and Candona sp..

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

    Science.gov (United States)

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

    2015-12-01

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

  7. South Equatorial Current (SEC) driven changes at DSDP Site 237, Central Indian Ocean, during the Plio-Pleistocene: Evidence from Benthic Foraminifera and Stable Isotopes

    Science.gov (United States)

    Gupta, Anil K.; Das, Moumita; Bhaskar, K.

    2006-12-01

    This study attempts to analyse paleoceanographic changes in the Central Indian Ocean (Deep Sea Drilling Project Site 237), linked to monsoon variability as well as deep-sea circulation during the Plio-Pleistocene. We used factor and cluster analyses of census data of the 34 most dominant species of benthic foraminifera that enabled us to identify five biofacies: Astrononion umbilicatulum- Uvigerina proboscidea (Au-Up), Pullenia bulloides- Bulimina striata (Pb-Bs), Globocassidulina tumida- Nuttallides umbonifera (Gt-Nu), Gyroidinoides nitidula- Cibicides wuellerstorfi (Gn-Cw) and Cassidulina carinata- Cassidulina laevigata (Cc-Cl) biofacies. Knowledge of the environmental preferences of modern deep-sea benthic foraminifera helped to interpret the results of factor and cluster analyses in combination with oxygen and carbon isotope values. The biofacies indicative of high surface productivity, resulting from a stronger South Equatorial Current (Au-Up and Pb-Bs biofacies), dominate the early Pliocene interval (5.6-4.5 Ma) of global warmth. An intense Indo-Pacific 'biogenic bloom' and strong Oxygen Minimum Zone extended to intermediate depths (˜1000-2000 m) over large parts of the Indian Ocean in the early Pliocene. Since 4.5 Ma, the food supply in the Central Indian Ocean dropped and fluctuated while deep waters were corrosive (biofacies Gt-Nu, Gn-Cw). The Pleistocene interval is characterized by an intermediate flux of organic matter (Cc-Cl biofacies).

  8. Use of stable isotope ratios to delineate coastal benthic food web structure in Adélie Land (East Antarctica)

    OpenAIRE

    Michel, Loïc; Dubois, Philippe; Eleaume,Marc; Fournier, Jérôme; Gallut, Cyril; Jane, Philip; Lepoint, Gilles

    2016-01-01

    Antarctica currently undergoes strong and contrasted impacts linked with climate change. While the West Antarctic Peninsula is one of the most rapidly warming regions in the world, resulting in sea ice cover decrease, in some parts of East Antarctica sea ice cover tends to increase, possibly in relation with changes in atmospheric circulation. Changes in sea ice cover are likely to influence benthic food web structure through modifications of benthic-pelagic coupling, disruption of benthic pr...

  9. Diversity Patterns of Benthic Macrofauna Caused by Marine Fish Farming

    Directory of Open Access Journals (Sweden)

    Arnaldo Marín

    2011-04-01

    Full Text Available This paper reviews the patterns observed in the diversity and structure of the macrofauna benthic community under the influence of fish farming. First, we explain the effects of organic enrichment on the sediment and the consequences for the inhabiting communities. We describe the diversity trends in spatial and temporal gradients affected by fish farming and compare them with those described by the Pearson and Rosenberg model. We found that in general terms, the trends of diversity and other community parameters followed the Pearson and Rosenberg model but they can vary to some extent due to sediment local characteristics or to secondary disturbances. We also show the different mechanisms by which wild fish can affect macrofauna diversity patterns under fish farming influence. In addition, we comment the importance of the macrofauna diversity in the ecosystem functions and propose some guidelines to measure functional diversity related to relevant processes at ecosystem level. We propose more research efforts in the main topics commented in this review to improve management strategies to guarantee a good status of the diversity and ecosystem functioning of sediments influenced by fish farming.

  10. New perspectives in benthic deep-sea microbial ecology

    Directory of Open Access Journals (Sweden)

    Cinzia eCorinaldesi

    2015-03-01

    Full Text Available Deep-sea ecosystems represent the largest and most remote biome of the biosphere. They play a fundamental role in global biogeochemical cycles and their functions allow existence of life on our planet. In the last 20 years enormous progress has been made in the investigation of deep-sea microbes, but the knowledge of the microbial ecology of the soft bottoms (representing >90% of the deep-sea floor surface is still very limited. Deep-sea sediments host the largest fractions of Bacteria, Archaea and viruses on Earth, and potentially, a high diversity. At the same time, available results from metagenomics suggest that a large fraction of microbial taxa is completely unknown to science. Estimating the diversity of deep-sea benthic microbes and understanding their functions are some of the challenges of absolute priority, not only for deep-sea microbial ecology, but also for the entire research field of life sciences. The achievement of these goals, given the importance of the deep-sea microbial life for the functioning of the global biosphere, will open new perspectives for the comprehension of adaptation processes to the impact of global changes.

  11. Regulation of nitrous oxide emission associated with benthic invertebrates

    DEFF Research Database (Denmark)

    Stief, Peter; Schramm, Andreas

    2010-01-01

    of their bioirrigation behaviour (indirect N2O emission). 2. Two benthic invertebrate species were studied to determine (i) the dependence of direct N2O emission on the preferred diet of the animals, (ii) the regulation of direct N2O emission by seasonally changing factors, such as body size, temperature and NO3......- availability and (iii) the quantitative relationship between direct and indirect N2O emission. 3. Larvae of the mayfly Ephemera danica, which prefer a bacteria-rich detritus diet, emitted N2O at rates of up to 90 pmol Ind.-1 h-1 under in situ conditions and 550 pmol Ind.-1 h-1 under laboratory conditions....... In contrast, larvae of the alderfly Sialis lutaria, which prefer a bacteria-poor carnivorous diet, emitted N2O at invariably low rates of 0–20 pmol Ind.-1 h-1. The N2O emission rate of E. danica larvae was positively correlated with seasonally changing factors (body size, temperature and NO3- availability...

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

    Mariotti, G.; Fagherazzi, S.

    2012-12-01

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

  14. Benthic boundary layer. IOS observational and modelling programme

    International Nuclear Information System (INIS)

    Near bottom currents, measured at three sites in the N.E. Atlantic, reveal the eddying characteristics of the flow. Eddies develop, migrate and decay in ways best revealed by numerical modelling simulations. Eddies control the thickness of the bottom mixed layer by accumulating and thickening or spreading and thinning the bottom waters. At the boundaries of eddies benthic fronts form providing a path for upward displacement of the bottom water. An experiment designed to estimate vertical diffusivity is performed. The flux of heat into the bottom of the Iberian basin through Discovery Gap is deduced from year long current measurements. The flux is supposed balanced by geothermal heating through the sea floor and diapycnal diffusion in the water. A diffusivity of 1.5 to 4 cm2 s-1 is derived for the bottom few hundred meters of the deep ocean. Experiments to estimate horizontal diffusivity are described. If a tracer is discharged from the sea bed the volume of sea water in which it is found increases with time and after 20 years will fill an ocean basin of side 1000 km to a depth of only 1 to 2 km. (author)

  15. Phase zone photon sieve

    Institute of Scientific and Technical Information of China (English)

    Jia Jia; Xie Chang-Qing

    2009-01-01

    A novel diffractive optical element, named phase zone photon sieve (PZPS), is presented. There are three kinds of phase plates in PZPSs: PZPS1, PZPS2, and PZPS3. Each of the PZPSs has its own structure and is made on quartz substrate by etching. The three PZPSs have stronger diffraction peak intensity than a photon sieve (PS) when the margin pinhole and zone line width are kept the same. The PZPS3 can produce a smaller central diffractive spot than the ordinary PS with the same number of zones on the Fresnel zone plate. We have given the design method for and the simulation of PZPS and PS. PZPS has potential applications in optical maskless lithography.

  16. BLM Solar Energy Zones

    Data.gov (United States)

    Bureau of Land Management, Department of the Interior — Priority development areas for utility-scale solar energy facilities as identified in the Solar PEIS Record of Decision. An additional Solar Energy Zone identified...

  17. Phase zone photon sieve

    International Nuclear Information System (INIS)

    A novel diffractive optical element, named phase zone photon sieve (PZPS), is presented. There are three kinds of phase plates in PZPSs: PZPS1, PZPS2, and PZPS3. Each of the PZPSs has its own structure and is made on quartz substrate by etching. The three PZPSs have stronger diffraction peak intensity than a photon sieve (PS) when the margin pinhole and zone line width are kept the same. The PZPS3 can produce a smaller central diffractive spot than the ordinary PS with the same number of zones on the Fresnel zone plate. We have given the design method for and the simulation of PZPS and PS. PZPS has potential applications in optical maskless lithography. (classical areas of phenomenology)

  18. : Seizure onset zone imaging

    OpenAIRE

    David, Olivier; Blauwblomme, Thomas; Job, Anne-Sophie; Chabardès, Stéphan; Hoffmann, Dominique,; Minotti, Lorella; Kahane, Philippe

    2011-01-01

    International audience Stereo-electroencephalography is used to localize the seizure onset zone and connected neuronal networks in surgical candidates suffering from intractable focal epilepsy. The concept of an epileptogenicity index has been proposed recently to represent the likelihood of various regions being part of the seizure onset zone. It quantifies low-voltage fast activity, the electrophysiological signature of seizure onset usually assessed visually by neurologists. Here, we re...

  19. Benthic foraminifera at the Cretaceous-Tertiary boundary around the Gulf of Mexico

    Science.gov (United States)

    Alegret, Laia; Molina, Eustoquio; Thomas, Ellen

    2001-10-01

    Cretaceous-Tertiary (K-T) boundary sections in northeastern Mexico contain marly formations separated by a controversial clastic unit. Benthic foraminifera in seven sections indicate middle and lower bathyal depths of deposition for the marls, with the exception of the upper bathyal northernmost section. Mixed neritic-bathyal faunas were present in the clastic unit, indicating redeposition in the deep basin by mass-wasting processes resulting from the K-T bolide impact in the Gulf of Mexico. Benthic foraminifera in the Mexican sections, and at other deep-sea locations, were not subject to major extinction at the time of impact, but there were temporary changes in assemblage composition. Benthic faunas indicate well- oxygenated bottom waters and mesotrophic conditions during the late Maastrichtian and increased food supply during the latest Maastrichtian. The food supply decreased drastically just after the K-T boundary, possibly because of the collapse of surface productivity. Cretaceous and early Paleogene benthic foraminifera, however, did not exhibit the benthic-pelagic coupling of present-day faunas, as documented by the lack of significant extinction at the K-T collapse of surface productivity. Much of the food supplied to the benthic faunas along this continental margin might have been refractory material transported from land or shallow coastal regions. The decrease in food supply at the K-T boundary might be associated with the processes of mass wasting, which removed surface, food-rich sediment. Benthic faunas show a staggered pattern of faunal recovery in the lowermost Paleogene, consistent with a staged recovery of the vertical organic flux but also with a gradual buildup of organic matter in the sediment.

  20. Occurrence of benthic microbial nitrogen fixation coupled to sulfate reduction in the seasonally hypoxic Eckernförde Bay, Baltic Sea

    DEFF Research Database (Denmark)

    Bertics, V. J.; Löscher, C. R.; Salonen, I.; Dale, A. W.; Gier, J.; Schmitz, R. A.; Treude, T.

    2013-01-01

    Despite the worldwide occurrence of marine hypoxic regions, benthic nitrogen (N) cycling within these areas is poorly understood and it is generally assumed that these areas represent zones of intense fixed N loss from the marine system. Sulfate reduction can be an important process for organic...... oxidation. The objective of this study was to evaluate if N2 fixation, possibly by SRB, plays a role in N cycling within the seasonally hypoxic sediments from the Eckernförde Bay, Baltic Sea. Monthly samplings were performed over the course of one year to measure nitrogenase activity (NA) and sulfate......-fixing community was examined via molecular tools. Integrated rates of N2 fixation (approximated from NA) and sulfate reduction showed a similar seasonality pattern, with highest rates occurring in August (approx. 22 and 880 nmol cm-3 d-1 of N and SO42−, respectively) and October (approx. 22 and 1300 nmol cm...

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

    Science.gov (United States)

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

    2015-04-01

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

  2. 75 FR 3859 - Safety Zone; Baltimore Captain of Port Zone

    Science.gov (United States)

    2010-01-25

    ..., 2008 issue of the Federal Register (73 FR 3316). Public Meeting We do not now plan to hold a public... SECURITY Coast Guard 33 CFR Part 165 RIN 1625-AA00 Safety Zone; Baltimore Captain of Port Zone AGENCY... establishing a temporary safety zone in all navigable waters of the Captain of the Port Baltimore zone....

  3. Response of deep-sea benthic foraminifera to Miocene paleoclimatic events, DSDP site 289

    International Nuclear Information System (INIS)

    Changes in the Miocene deep-sea benthic foraminifera at DSDP Site 289 closely correlate to the climatically induced variations in deep and bottom waters in the Pacific Ocean. In early Miocene time, oxygen and carbon isotopes indicate that bottom waters were relatively warm and poorly oxygenated. Benthic foraminiferal assemblages are characterized by various species inherited from the Oligocene. Expansion of the Antarctic icecap in the early middle Miocene, 14-16 m.y. ago, increased oxygen isotope values, produced cold, more oxygenated bottom waters and lead to a turnover in the benthic foraminifera. An Oligocene-early Miocene assemblage was replaced by a cibicidoid-dominated assemblage. Some species became extinct and benthic faunas became more bathymetrically restricted with the increased stratification of deep waters in the ocean. In mid-Miocene time, Epistominella exigua and E. umbonifera, indicative of young, oxygenated bottom waters, are relatively common at DSDP Site 289. Further glacial expansion 5-9 m.y. ago lowered sealevel, increased oceanic upwelling and associated biological productivity and intensified the oxygen minima. Abundant hispid and costate uvigerines become a dominant faunal element at shallow depths above 2500 m as E. umbonifera becomes common to abundant below 2500 m. By late Miocene time, benthic faunas similar in species composition and proportion to modern faunas on the Ontong-Java plateau, had become established. (Auth.)

  4. Benthic macroinvertebrates diversity and water quality assessment at Sungai Congkak recreational area, Hulu Langat, Selangor

    Science.gov (United States)

    Mustaqim-Alias, M.; Ahmad, A. K.

    2013-11-01

    A study on benthic macroinvertebrates diversity and water quality assessment was conducted at Sungai Congkak recreational area in Hulu Langat, Selangor. Sums of eight sampling stations were selected with a distance of 100-200 m interval between each station. Benthic macroinvertebrates was sampled using a Surber net, while water sampling and analysis were undertaken according to HACH standard methods. A total of 3754 individuals from 40 families of benthic macroinvertebrates were recorded at this river. Ecological indices namely Shannon diversity index (2.49), Pielou evenness index (0.77) and Margalef richness index (4.06) demonstrate that Sungai Congkak is at good condition and benthic macroinvertebrates has homogeneous distribution along the sampling sites. Elmidae, Hydrophilidae, Baetidae and Perlidae were most dominant families present in that area and adapted progressively with excellent water quality (> 300 individuals). As regards to Malaysian's Water Quality Index (WQI), the study area at Sungai Congkak is classified in class I which has good water quality conditions. The Pearson correlation test indicates that ecological indices have strong correlation toward WQI at all sampling stations. As a conclusion, the benthic macroinvertebrates and WQI data demonstrated that Sungai Congkak is clean and suitable as recreational stream based on this study.

  5. Benthic Collector and Grazer Communities Are Threatened by Hemlock Woolly Adelgid-Induced Eastern Hemlock Loss

    Directory of Open Access Journals (Sweden)

    Joshua K. Adkins

    2015-08-01

    Full Text Available Eastern hemlock (Tsuga canadensis (L. is a foundation species in eastern North America where it is under threat from the highly invasive, exotic hemlock woolly adelgid (Adelges tsugae. Eastern hemlock is especially important in riparian areas of Central and Southern Appalachia, so we compared the spatial and temporal composition of benthic collector-gatherers, collector-filterers, and grazers in headwater streams with hemlock-dominated riparian vegetation to those with deciduous tree-dominated riparian vegetation to evaluate the extent to which adelgid-induced hemlock loss could influence composition and abundance of these two functional feeding groups. We found differences in benthic invertebrate abundance and family-level diversity based on riparian vegetation and sampling approach, and, often, riparian vegetation significantly interacted with location or season. Collector-gatherers and grazers were more abundant in eastern hemlock streams in the summer, when hemlock litter is readily available and deciduous litter is relatively sparse. Riparian eastern hemlock appears to exert considerable influence on benthic invertebrate functional feeding group composition in headwater stream communities, as expected with a foundation species. With the loss of eastern hemlock due to adelgid-induced mortality, we should expect to see alterations in spatial and temporal patterns of benthic invertebrate abundance and diversity, with potential consequences to both benthic and terrestrial ecosystem function.

  6. Species Diversity of Macro-benthic Invertebrates in Mangrove and Seagrass Ecosystems of Eastern Bohol, Philippines

    Directory of Open Access Journals (Sweden)

    Marichu C. Libres

    2015-12-01

    Full Text Available Descriptive survey method through actual resource assessment was conducted to determine the species diversity of macro-benthic invertebrates in the mangrove forest and seagrass beds of Eastern Bohol, Philippines namely: Anda, Candijay, Mabini, and Ubay. The 4 representative sites were chosen through random sampling. In each municipality, the researcher selected a representative area wherein 3 transects were laid perpendicular to the shoreline. The assessment in each transect covered a strip of 4 m by 50 m. All macro-benthic invertebrates intercepted within 4-meter to the left and right of the transect line were identified, counted and listed in a slate board. The data gathered were subjected to Shannon-Weiner Index and Kruskal Wallis Test. In mangrove forests, results revealed that Anda got the highest species diversity index of 1.66 with 11 species. The lowest value which is 1.15 was recorded in Candijay having only five macro-benthic invertebrate species. In the 4 municipalities, a total of 12 species representing 3 phyla were identified. In seagrass beds, 19 taxa of macro-benthic invertebrates were recorded belonging to three phyla. Based on the findings, the researcher concluded that macro-benthic invertebrates in eastern part of Bohol is diverse both in mangrove forests and seagrass beds. Moreover, there is no significant difference in the species diversity among the four representative sites.

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

    Science.gov (United States)

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

    2015-12-01

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

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

    Science.gov (United States)

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

    2015-09-01

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

  9. Benthic invertebrates structure in wetlands of a tributary of the middle Parana River (Argentina) affected by hydrologic and anthropogenic disturbances.

    Science.gov (United States)

    Marchese, Mercedes R; Rodriguez, Alba R; Pave, Paola J; Carignano, Maria R

    2008-05-01

    The present study was aimed at analyzing chromium concentrations in water column and bottom sediments in the main channel of Northern Salado River (tributary of Middle Parana River) and its floodplain. The main changes caused by human activities and hydrological disturbances on benthic invertebrate structure were also analyzed. Sediment concentrations of the reference area varied between 44.2 and 97.1 microg Crg(-1) (dw), and in the impacted zone, between 85.5 and 209 microg Cr g(-1) (dw) reaching the highest values in the wetland floodplain. Alfa, beta and gamma diversities in the reference section have been 33, 9 and 66 species, and in the disturbed section, they have been 37, 8.33 and 74 species, respectively The species dominant in the disturbed habitats were characterized by a small body size and short life cycles, as the species of olig chaetes Naidinae. The extreme flooding produced a rejuvenation of the area with the consequent physical re-structuration produced by flooding, showing: a marked decrease in chromium levels in sediments and in organic matter content, which allowed the colonization of insects (Ephemeroptera and Trichoptera). PMID:18972689

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

    Directory of Open Access Journals (Sweden)

    Ulrike Braeckman

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

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

    Science.gov (United States)

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

    2011-01-01

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

  12. Extremely heat tolerant photosymbiosis in a shallow marine benthic foraminifera

    Science.gov (United States)

    Schmidt, Christiane; Danna, Titelboim; Janett, Brandt; Raphael, Morard; Barak, Herut; Sigal, Abramovich; Ahuva, Almogi-Labin; Michal, Kucera

    2016-04-01

    Thermal stress leads to the loss of algal symbionts (bleaching) in many shallow marine calcifiers including foraminifera. The bleaching threshold often occurs at water temperatures, which are likely to be exceeded in the near future due to global warming. Preadaptation represents one mechanism allowing photosymbiotic organisms to persist under warmer conditions, providing the tolerance can be carried to new habitats. Here we provide evidence for the existence of such adaptation in the benthic foraminifera Pararotalia calcariformata recently discovered in the eastern Mediterranean. We identify its symbionts as a consortium of diatom species dominated by Minutocellus polymorphus. We show that in the field, the foraminifera retains its pigments at a thermally polluted site, where peak water temperatures reach 36°C. To test whether this tolerance represents a widespread adaptation, we conducted manipulative experiments exposing populations from an unpolluted site to elevated temperatures for up to three weeks. The populations were kept in co-culture with the more thermally sensitive diatom-bearing foraminifera Amphistegina lobifera. Reduced photosynthetic activity in A. lobifera occurred at 32°C whereas photochemical stress in P. calcariformata was first observed during exposure to 36°C and chronic photoinhibition (but not mortality) first occurred at 42°C. Survivorship was high in all treatments, and growth was observed under thermal conditions similar to summer maxima at the thermally polluted site (35-36°C). The photosymbiosis in P. calcariformata is unusually thermally tolerant for a photosymbiont-bearing eukaryote. The thermal tolerance of this photosymbiosis is present in a natural environment where its thermal threshold is never realized. These observations imply that photosymbiosis in marine protists can respond to elevated temperatures by drawing on a pool of naturally occurring pre-adaptations. It also provides a perspective on the massive occurrence of

  13. Benthic communities of shallow-water reefs of Abrolhos, Brazil

    Directory of Open Access Journals (Sweden)

    Roberto Villaça

    1997-01-01

    Full Text Available The benthic communities of fringing and mushroom-shaped shallow-water reefs of the Abrolhos region (southern coast of Bahia were surveyed. Line transects were used to estimate coral and algal percentage cover. Mussismilia braziliensis is the most conspicuous coral species in the majority of the communities surveyed, but turf algal make up the dominant cover in all but one studied reef. In general, communities on mushroom-shaped reefs have higher diversity and higher coral cover than on fringing reefs. For both reef morphologies, the coral to alga cover ratio does. not show marked differences between annual surveys, despite the high productivity characteristic of the dominant algal species.Foram estudadas comunidades bentônicas de pouca profundidade nos recifes em franja e chapeirões da região de Abrolhos (costa sul da Bahia. A cobertura das espécies foi estimada pelo método de transect de linha. Mussismilia braziliensis é a espécie de coral mais importante na maioria das comunidades estudadas, porém as algas em tufo são os organismos dominantes em todos os recifes estudados à exceção de apenas um. Em geral, as comunidades nos chapeirões têm maior diversidade e maior cobertura de coral do que as dos recifes em franja. Nos dois tipos de recife, a relação de cobertura coral-alga não apresenta diferença significativa no tempo, apesar da alta produtividade característica do tipo de alga dominante.

  14. Lipophilic toxin profiles detected in farmed and benthic mussels populations from the most relevant production zones in Southern Chile.

    Science.gov (United States)

    Garcia, Carlos; Rodriguez-Unda, Nelson; Contreras, Cristóbal; Barriga, Andrés; Lagos, Néstor

    2012-01-01

    Lipophilic toxins associated with diarrhoeic toxins were found in Mytilus chilensis (Blue mussels) and Aulacomya ater (Ribbed mussels). These shellfish samples were collected from Chiloe Island, Southern Chile. The samples were tested by liquid chromatography-tandem mass spectrometry (LC-MS/MS). After the analysis, four toxins were found: DTX-1, DTX-3, YTX and PTX. All toxins were identified by comparing their HPLC retention times with those of analytical standards and confirmed by LC-MS/MS. Dinophysistoxin-1 (DTX-1) and dinophysistoxin-3 (DTX-3) toxins were the major components within the mussel extracts. Nevertheless, the percentages of these toxins differed depending on the area they were collected from and/or the sampling date. The levels detected in Butacheuques Island for okadaic acid (OA) was 267 ± 3.5 µg OA eq kg(-1) (p < 0.05) and for DTX-3 was 183.4 ± 7.5 µg kg(-1) in ribbed mussels. Pectenotoxin (PTX) and yessotoxin (YTX) were the toxins detected in minor proportions in the toxic profile of the bivalves. The maximum concentration of YTX detected in ribbed mussels was 85.2 ± 2.8 µg kg(-1) in Mechuque Island, whereas the PTX-2 level in ribbed mussels was 82.0 ± 2.4 µg kg(-1) in Cailin Island. Analogues of YTX and PTX-2 were not detected in any of the analysed mussels, which did not support the supposed presence of isomers of toxins as a result of the enzymatic metabolism of bivalves. This study found evidence proving co-occurrence of lipophilic toxins - like PTX and YTX - with diarrhoeic toxin in samples collected in Southern Chile, which is, to date, the more complex mix of lipophilic toxins ever found in mussels samples from Southern Chile. PMID:22424031

  15. Response of Benthic Foraminifera to Organic Matter Quantity and Quality and Bioavailable Concentrations of Metals in Aveiro Lagoon (Portugal)

    Science.gov (United States)

    Martins, Maria Virgínia Alves; Silva, Frederico; Laut, Lazaro L. M.; Frontalini, Fabrizio; Clemente, Iara M. M. M.; Miranda, Paulo; Figueira, Rubens; Sousa, Silvia H. M.; Dias, João M. Alveirinho

    2015-01-01

    This work analyses the distribution of living benthic foraminiferal assemblages of surface sediments in different intertidal areas of Ria de Aveiro (Portugal), a polihaline and anthropized coastal lagoon. The relationships among foraminiferal assemblages in association with environmental parameters (temperature, salinity, Eh and pH), grain size, the quantity and quality of organic matter (enrichment in carbohydrates, proteins and lipids), pollution caused by metals, and mineralogical data are studied in an attempt to identify indicators of adaptability to environmental stress. In particular, concentrations of selected metals in the surficial sediment are investigated to assess environmental pollution levels that are further synthetically parameterised by the Pollution Load Index (PLI). The PLI variations allowed the identification of five main polluted areas. Concentrations of metals were also analysed in three extracted phases to evaluate their possible mobility, bioavailability and toxicity in the surficial sediment. Polluted sediment in the form of both organic matter and metals can be found in the most confined zones. Whereas enrichment in organic matter and related biopolymers causes an increase in foraminifera density, pollution by metals leads to a decline in foraminiferal abundance and diversity in those zones. The first situation may be justified by the existence of opportunistic species (with high reproduction rate) that can live in low oxic conditions. The second is explained by the sensitivity of some species to pressure caused by metals. The quality of the organic matter found in these places and the option of a different food source should also explain the tolerance of several species to pollution caused by metals, despite their low reproductive rate in the most polluted areas. In this study, species that are sensitive and tolerant to organic matter and metal enrichment are identified, as is the differential sensitivity/tolerance of some species to

  16. Geodatabase of benthic organisms for the Florida Coral Reef Tract from 1996-01-01 to 2012-01-01 (NODC Accession 0123059)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The Benthic Organisms of the Florida Keys National Marine Sanctuary geodatabase is a collection of information on the distribution of benthic organisms within the...

  17. Benthic data for corals, macroalgae, invertebrates, and non-living bottom types from 12 sites in American Samoa, 2005-2009. (NODC Accession 0068364)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Benthic transects were repeated at 12 sites around Tutuila at various depths on the reef slopes and flats. Benthic coverage categories include coral species,...

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

    Science.gov (United States)

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

    2014-05-01

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

  19. Response of benthic foraminifera to phytodetritus in the eastern Arabian Sea under low oxygen conditions

    Science.gov (United States)

    Enge, Annekatrin; Wukovits, Julia; Wanek, Wolfgang; Watzka, Margarete; Witte, Ursula; Hunter, William; Heinz, Petra

    2016-04-01

    At water depths between 100 and 1500 m a permanent Oxygen Minimum Zone (OMZ) impinges on the sea floor in the eastern Arabian Sea, exposing benthic organisms to anoxic to suboxic conditions. The flux of organic matter to the sea floor is relatively high at these depths but displays seasonal variation. Deposition of relatively fresh phytodetrital material (phytoplankton remains) can occur within a short period of time after monsoon periods. Several organism groups including foraminifera are involved to different extent in the processing of phytodetritus in the OMZs of the northern Arabian Sea. A series of in situ feeding experiments were performed to study the short-term processing (days) of organic carbon, nitrogen and nutritional demands of foraminifera at different oxygen concentrations on the continental margin in the eastern Arabian Sea. For the experiments, a single pulse of isotopically labeled phytodetritus was added to the sediment along a depth transect (540-1100 m) on the Indian Margin, covering the OMZ core and the lower OMZ boundary region. Uptake of phytodetritus within 4 days shows the relevance of phytodetritus as food source for foraminifera. Lower content of phytodetrital carbon recorded in foraminifera from more oxygenated depths shows greater food uptake by foraminifera in the OMZ core than in the OMZ boundary region. The foraminiferal assemblage living under almost anoxic conditions in the OMZ core is dominated by species typically found in eutroph environments (such as Uvigerinids) that are adapted to high flux of organic matter. The elevated carbon uptake can also result from missing food competition by macrofauna or from greater energy demand in foraminifera to sustain metabolic processes under hypoxic stress. Variable levels and ratios of phytodetrital carbon and nitrogen indicate specific nutritional demands and storage of food-derived nitrogen in some foraminifera species under near anoxia where the mean phytodetrital nitrogen content in

  20. Autofluorescence imaging system to discriminate and quantify the distribution of benthic cyanobacteria and diatoms

    DEFF Research Database (Denmark)

    Carreira, Cátia; Staal, Marc Jaap; Middelboe, Mathias;

    2015-01-01

    Observation of benthic photoautotrophs on sediment surfaces shows a single algal layer without distinction between photosynthetic groups. Until now it has not been possible to distinguish between benthic photosynthetic microorganisms, i.e. cyanobacteria and diatoms, at μm to mm scales using...... a single nondisruptive system. Chlorophyll autofluorescence can be used to distinguish different photoautotrophic groups if the correct excitation light is applied. Using this principle, a nonintrusive technique was developed to study the spatial distribution of benthic cyanobacteria and diatoms. By means...... of a charge coupled device camera, diatoms and cyanobacteria could be identified by blue light (470 nm) excitation and amber light (600 nm) excitation, respectively. By this approach, diatom or cyanobacterial dominance could be easily distinguished using the blue over amber ratio. We applied this method...

  1. Empirical approaches to more accurately predict benthic-pelagic coupling in biogeochemical ocean models

    Science.gov (United States)

    Dale, Andy; Stolpovsky, Konstantin; Wallmann, Klaus

    2016-04-01

    The recycling and burial of biogenic material in the sea floor plays a key role in the regulation of ocean chemistry. Proper consideration of these processes in ocean biogeochemical models is becoming increasingly recognized as an important step in model validation and prediction. However, the rate of organic matter remineralization in sediments and the benthic flux of redox-sensitive elements are difficult to predict a priori. In this communication, examples of empirical benthic flux models that can be coupled to earth system models to predict sediment-water exchange in the open ocean are presented. Large uncertainties hindering further progress in this field include knowledge of the reactivity of organic carbon reaching the sediment, the importance of episodic variability in bottom water chemistry and particle rain rates (for both the deep-sea and margins) and the role of benthic fauna. How do we meet the challenge?

  2. Sediment characteristics and benthic ecological status in contrasting marine environments of subtropical Hong Kong.

    Science.gov (United States)

    Chan, Alice K Y; Xu, Wen-Zhe; Liu, Xiao-Shou; Cheung, Siu Gin; Shin, Paul K S

    2016-02-15

    Sediment characteristics and benthic communities on a finer sampling scale in four contrasting environments in subtropical Hong Kong were analyzed in summer and winter 2012. In two harbour habitats which suffered from historic sewage pollution or hypoxic events, organic carbon, nutrient and trace metal content in the sediment were significantly higher than that in an offshore area and a marine reserve. The relatively low organic and nutrient content in the offshore habitat could be resulted from enhanced resuspension of such materials from the seabed owing to intense water mixing and disturbance caused by bottom trawling. The biotic indices AMBI and M-AMBI were shown to be useful in assessing the benthic ecological status of these habitats. Such indices can also be more sensitive than sediment physico-chemical parameters in differentiating the response of macrofauna to seasonal changes in the benthic environment. PMID:26749224

  3. Complex spatial and temporal variation of subtropical benthic macrofauna under sewage impact.

    Science.gov (United States)

    Souza, F M; Brauko, K M; Gilbert, E R; Martins, C C; Lana, P C; Camargo, M G

    2016-05-01

    To better understand variation in sewage-impacted benthic macrofauna from subtropical tidal flats over time and space, we applied a five-factor linear model at a hierarchy of spatial (Condition - Contaminated or Non-Contaminated, Tidal Flat and Plot) and temporal scales (Season and Fortnight). The Contaminated site showed high levels of coprostanol and the presence of Paranais cf frici as markers or indicators of organic enrichment. Differences between Seasons were more pronounced for the faunal variation patterns than for the other parameters, with lower species richness and abundance in summer. There were significant interactions between Fortnight and Tidal Flat for most variables, reflecting marked heterogeneity within Tidal Flats. Benthic community has significantly changed over short periods of time. These rapid changes may lead to erroneous interpretations and mask the true sources of variation. Our results clearly demonstrate the need to better understand benthic temporal variability even at small scales. PMID:26994465

  4. Modelling impacts and recovery in benthic communities exposed to localised high CO2.

    Science.gov (United States)

    Lessin, Gennadi; Artioli, Yuri; Queirós, Ana M; Widdicombe, Stephen; Blackford, Jerry C

    2016-08-15

    Regulations pertaining to carbon dioxide capture with offshore storage (CCS) require an understanding of the potential localised environmental impacts and demonstrably suitable monitoring practices. This study uses a marine ecosystem model to examine a comprehensive range of hypothetical CO2 leakage scenarios, quantifying both impact and recovery time within the benthic system. Whilst significant mortalities and long recovery times were projected for the larger and longer term scenarios, shorter-term or low level exposures lead to reduced projected impacts. This suggests that efficient monitoring and leak mitigation strategies, coupled with appropriate selection of storage sites can effectively limit concerns regarding localised environmental impacts from CCS. The feedbacks and interactions between physiological and ecological responses simulated reveal that benthic responses to CO2 leakage could be complex. This type of modelling investigation can aid the understanding of impact potential, the role of benthic community recovery and inform the design of baseline and monitoring surveys. PMID:27289279

  5. Bioaccumulation of sediment-bound Cr-51, Ni-63 and C-14 by benthic invertebrates

    International Nuclear Information System (INIS)

    Sediments in many areas of the Baltic Sea are highly contaminated with particle-reactive trace metals and/or radionuclides. These may be re-mobilised into aquatic food chains by bioaccumulation into benthic organisms. In this study, we examined and compared assimilation efficiencies and bioaccumulation kinetics (rates of uptake and elimination) of sediment-associated Cr-51, Ni-63 and organic-associated C- 14 in three common benthic invertebrates from the Baltic Sea (the bivalve Macoma balthica, the amphipod Monoporeia affinis and the priapulid worm Halicryptus spinulosus). There were differences between animals and radionuclides in both the rate of uptake and elimination and the maximum amount accumulated. Understanding how and to what degree different deposit-feeding benthic invertebrates are exposed to and bio-accumulate sediment-associated metals are important for both ecological risk assessment and management decisions in coastal ecosystems. (author)

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

    Science.gov (United States)

    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.

  7. Zones of emotional labour

    DEFF Research Database (Denmark)

    Strøbæk, Pernille Solveig

    2011-01-01

    The paper suggests that due to the difficult nature of their work public family law caseworkers are to be included in the definition of emotional labour even though they are omitted by Hochschild. Based upon a review of the structures involved in emotional labour an explorative qualitative study is...... put forth among 25 Danish public family law caseworkers. The study points to personal, professional, and social zones of emotional labour through which the caseworkers carry out their work. Emotional labour zones mark emotion structures that may be challenging due to complex emotional intersections...

  8. ZoneLib

    DEFF Research Database (Denmark)

    Jessen, Jan Jacob; Schiøler, Henrik

    2006-01-01

    We present a dynamic model for climate in a livestock building divided into a number of zones, and a corresponding modular Simulink library (ZoneLib). While most literature in this area consider air flow as a control parameter we show how to model climate dynamics using actual control signals...... for the ventilation equipment. To   overcome a shortcoming in Simulink to solve algebraic equations and matrix inversions, we have developed the library inspired by the so called dynamic node technique. We present simulation results using the presented library, and concludes with visions for further...

  9. Grid zone drone

    OpenAIRE

    McCarthy, Clive; Cooper, Graham; Field, James; Thayne, Martyn; Vickers, Richard

    2014-01-01

    From 16th – 19th October 2014, co_LAB presented its newest creation, Grid Zone Drone, at Kinetica – an international exhibition providing a global platform for galleries, curatorial groups, design studios and artists working with new media art. 2014 marked the third consecutive year that the University of Lincoln has been represented at the global art fair. Grid Zone Drone represents a continuation of the group’s research into ‘drone culture’, and explores the detachment of the drone withi...

  10. Evaluation of Environmental Factors to Determine the Distribution of Functional Feeding Groups of Benthic Macroinvertebrates Using an Artificial Neural Network

    NARCIS (Netherlands)

    Verdonschot, P.F.M.

    2008-01-01

    Functional feeding groups (FFGs) of benthic macroinvertebrates are guilds of invertebrate taxa that obtain food in similar ways, regardless of their taxonomic affinities. They can represent a heterogeneous assemblage of benthic fauna and may indicate disturbances of their habitats. The proportion of

  11. Benthic solute exchange and carbon mineralization in two shallow subtidal sandy sediments: Effect of advective pore-water exchange

    DEFF Research Database (Denmark)

    Cook, Perran L. M.; Wenzhofer, Frank; Glud, Ronnie N.;

    2007-01-01

    proceeded predominantly through sulfate reduction when benthic mineralization rates were high and advective pore-water flow low as a result of poorly developed topography. Previous studies of benthic mineralization in shallow sandy sediments have generally ignored these dynamics and, hence, have overlooked...

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

    Science.gov (United States)

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

    2016-04-01

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

  13. Assessing the suitability of benthic foraminiferal morpho-groups to reconstruct paleomonsoon from Bay of Bengal

    Science.gov (United States)

    Manasa, M.; Saraswat, Rajeev; Nigam, Rajiv

    2016-04-01

    Temporal changes in benthic foraminiferal morpho-groups were suggested as an effective proxy to reconstruct past monsoon intensity from the Arabian Sea. Here, in order to test the applicability of temporal variation in morpho-groups to reconstruct past monsoon intensity from the Bay of Bengal, we have documented recent benthic foraminiferal distribution from the continental shelf region of the northwestern Bay of Bengal. Based on the external morphology, benthic foraminifera were categorized into rounded symmetrical (RSBF) and angular asymmetrical benthic foraminifera (AABF). Additionally, a few other dominant groups were also identified based on test composition (agglutinated, calcareous) and abundance (Asterorotalids and Nonions). The relative abundance of each group was compared with the ambient physico-chemical conditions, including dissolved oxygen, organic matter, salinity and temperature. We report that the RSBF are abundant in comparatively warm and well oxygenated waters of low salinity, suggesting a preference for high energy environment, whereas AABF dominate relatively cold, hypersaline deeper waters with low dissolved oxygen, indicating a low energy environment. The agglutinated foraminifera, Asterorotalids and Nonions dominate shallow water, low salinity regions, whereas the calcareous benthic foraminiferal abundance increases away from the riverine influx regions. Food availability, as estimated from organic carbon abundance in sediments, has comparatively less influence on faunal distribution in the northwestern Bay of Bengal, as compared to dissolved oxygen, temperature and salinity. We conclude that the factors associated with freshwater influx affect the distribution of benthic foraminiferal morpho-groups in the northwestern Bay of Bengal and thus it can be used to reconstruct past monsoon intensity from the Bay of Bengal.

  14. Mapping ecosystem services provided by benthic habitats in the European North Atlantic Ocean

    Directory of Open Access Journals (Sweden)

    Ibon eGalparsoro

    2014-07-01

    Full Text Available Mapping and assessing the ecosystem services provided by benthic habitats are a highly valuable source of information for understanding their current and potential benefits to society. The main objective of this investigation is to assess and map the ecosystem services provided by benthic habitats of the European North Atlantic Ocean, in the context of Mapping and Assessment of Ecosystems and their Services (MAES programme, the European Biodiversity Strategy and the implementation of the Marine Strategy Framework Directive. In total, 62 habitats have been analysed in relation to 12 ecosystem services over 1.7 million km2. Results indicated that more than 90% of the mapped area provides biodiversity maintenance and food provision services; meanwhile grounds providing reproduction and nursery services are limited to half of the mapped area. Benthic habitats generally provide more services closer to shore than offshore and in shallower waters. This gradient is likely to be explained by difficult access (i.e. distance and depth and lack of scientific knowledge for most of the services provided by distant benthic habitats. This research has provided a first assessment of the benthic ecosystem services at Atlantic European scale, with the provision of ecosystem services maps and their general spatial distribution patterns. Related to the objectives of this research, the conclusions are: (i benthic habitats provide a diverse set of ecosystem services, being the food provision and biodiversity maintenance services the ones that are more extensively represented. In addition, other regulating and cultural services are provided in a more limited area; and (ii the ecosystem services assessment categories are significantly related to the distance to the coast and with depth (higher near the coast and in shallow waters.

  15. Drivers of abundance and community composition of benthic macroinvertebrates in Ottawa River sediment near Chalk River Laboratories

    International Nuclear Information System (INIS)

    The Ottawa River has received effluent from Chalk River Laboratories (CRL) for more than 60 years. Some radionuclides and contaminants released in effluents are bound rapidly to particles and deposited in bottom sediments where they may be biologically available to benthic invertebrates and other aquatic biota. As part of a larger ecological assessment, we assess the potential impact of contaminated sediments in the vicinity of CRL on local benthic community structure. Using bivariate and multivariate approaches, we demonstrate that CRL operations have had little impact on the local benthic community. Despite elevated anthropogenic radionuclide activity concentrations in sediment near CRL's process outfall, the benthic community is no less abundant or diverse than what is observed upstream at background levels. The Ottawa River benthic invertebrate community is structured predominantly by natural physical and biological conditions in the sediment, specifically sediment water content and organic content. These natural habitat conditions have a stronger influence on macroinvertebrate communities than sediment contamination. (author)

  16. Drivers of abundance and community composition of benthic macroinvertebrates in Ottawa River sediment near Chalk River Laboratories

    Energy Technology Data Exchange (ETDEWEB)

    Bond, M.J.; Rowan, D.; Silke, R.; Carr, J., E-mail: bondm@aecl.ca [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada)

    2013-12-15

    The Ottawa River has received effluent from Chalk River Laboratories (CRL) for more than 60 years. Some radionuclides and contaminants released in effluents are bound rapidly to particles and deposited in bottom sediments where they may be biologically available to benthic invertebrates and other aquatic biota. As part of a larger ecological assessment, we assess the potential impact of contaminated sediments in the vicinity of CRL on local benthic community structure. Using bivariate and multivariate approaches, we demonstrate that CRL operations have had little impact on the local benthic community. Despite elevated anthropogenic radionuclide activity concentrations in sediment near CRL's process outfall, the benthic community is no less abundant or diverse than what is observed upstream at background levels. The Ottawa River benthic invertebrate community is structured predominantly by natural physical and biological conditions in the sediment, specifically sediment water content and organic content. These natural habitat conditions have a stronger influence on macroinvertebrate communities than sediment contamination. (author)

  17. Cascading effects of flow reduction on the benthic invertebrate community in a lowland river

    DEFF Research Database (Denmark)

    Graeber, Daniel; Pusch, Martin T.; Lorenz, Stefan; Brauns, Mario

    2013-01-01

    Reduction of flow constitutes one of the most severe human alterations to rivers, as it affects the key abiotic feature of these ecosystems. While there has been considerable progress in understanding the effects of reduced flow on benthic macroinvertebrates, cascading effects of flow reduction on...... concentration minima of less than 5 mg l−1 which prevailed 74% of the days in summer. This depletion of DO after flow reduction presumably caused the observed species turnover. Hence, flow reduction in lowland rivers may not only directly impair the ecological functions provided by benthic macroinvertebrates...

  18. An unusually large phytoplankton spring bloom drives rapid changes in benthic diversity and ecosystem function

    Science.gov (United States)

    Zhang, Qingtian; Warwick, Richard M.; McNeill, Caroline L.; Widdicombe, Claire E.; Sheehan, Aaron; Widdicombe, Stephen

    2015-09-01

    In 2012, the Western English Channel experienced an unusually large and long-lived phytoplankton spring bloom. When compared with data from the past 20 years, average phytoplankton biomass at Station L4 (part of the Western Channel Observatory) was approximately 3× greater and lasted 50% longer than any previous year. Regular (mostly weekly) box core samples were collected from this site before, during and after the bloom to determine its impact on macrofaunal abundance, diversity, biomass, community structure and function. The spring bloom of 2012 was shown to support a large and rapid response in the majority of benthic taxa and functional groups. However, key differences in the precise nature of this response, as well as in its timing, was observed between different macrofauna feeding groups. Deposit feeders responded almost instantly at the start of the bloom, primarily thorough an increase in abundance. Suspension feeders and opportunistic/predatory/carnivorous taxa responded slightly more slowly and primarily with an increase in biomass. At the end of the bloom a rapid decline in macrobenthic abundance, diversity and biomass closely followed the decline in phytoplankton biomass. With suspension feeders showing evidence of this decline a few weeks before deposit feeders, it was concluded that this collapse in benthic communities was driven primarily by food availability and competition. However, it is possible that environmental hypoxia and the presence of toxic benthic cyanobacteria could also have contributed to this decline. This study shows evidence for strong benthic-pelagic coupling at L4; a shallow (50 m), coastal, fine-sand habitat. It also demonstrates that in such habitats, it is not just planktonic organisms that demonstrate clear community phenology. Different functional groups within the benthic assemblage will respond to the spring bloom in specific manner, with implications for key ecosystem functions and processes, such as secondary production

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

    Science.gov (United States)

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

    1988-01-01

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

  20. Toxicity Testing of Silver Nanoparticles in Artificial and Natural Sediments Using the Benthic Organism Lumbriculus variegatus

    DEFF Research Database (Denmark)

    Rajala, Juho Elias; Mäenpää, Kimmo; Vehniäinen, Eeva-Riikka;

    2016-01-01

    The increased use of silver nanoparticles (AgNP) in industrial and consumer products worldwide has resulted in their release to aquatic environments. Previous studies have mainly focused on the effects of AgNP on pelagic species, whereas few studies have assessed the risks to benthic invertebrates...... despite the fact that the sediments act as a large potential sink for NPs. In this study, the toxicity of sediment-associated AgNP was evaluated using the standard sediment toxicity test for chemicals provided by the Organization of Economic Cooperation and Development. The freshwater benthic oligochaete...

  1. Benthic mineralization and nutrient exchange over the inner continental shelf of western India.

    Digital Repository Service at National Institute of Oceanography (India)

    Pratihary, A.K.; Naqvi, S.W.A.; Narvenkar, G.; Kurian, S.; Naik, H.; Naik, R.; Manjunatha, B.R.

    different from those observed in cohesive sed- iments (Janssen et al., 2005; Rao et al., 2007; Cook et al., 2007). Our results are based on the flux measurement at a fixed study site on the inner shelf where the sediments are co- hesive in nature. We do... polychaetes comprised 85–95 %. Both these locations were dominated by silty-clayey cohesive sediments. 2 Materials and methods 2.1 Incubation method Over the last couple of decades, benthic respiration and nu- trient fluxes have been measured mainly by benthic...

  2. DNS zones revisited

    NARCIS (Netherlands)

    Wanrooij, van Ward; Pras, Aiko; Delgado Kloos, Carlos

    2005-01-01

    Recent research [Pap04b] suggests DNS reliability and performance is not up to the levels it should be due to misconfigurations. This paper checks the configuration of nameserver zones against additional requirements, recommendations and best-practices. It shows that almost one in four domains fails

  3. Zonation of macrofauna across sandy beaches and surf zones along the Dutch coast

    Directory of Open Access Journals (Sweden)

    Gerard Janssen

    2005-06-01

    Full Text Available On nine beaches and two transects in the surf zone along the Dutch coast the presence of benthic macrofauna was studied in relation to basic abiotic characteristics. According to Short's classification system, Dutch beaches are mesotidal and dissipative (Ω = 8.6, and the RTR is low (1.52-1.27, which means that they are not tide-dominated. BSI ranged from 1.4 to 1.1 for the northern and western Dutch coasts respectively and had an overall value of 1.2. The rates of exposure of the beaches varied between 8 and 12, and are therefore regarded as sheltered to moderately exposed. The Dutch beaches display a geographical trend in beach types. Those of the Wadden Sea islands in the northern part of the Netherlands are dissipative, flat, fine-grained, and host high densities of many species of benthic macrofauna. The beaches along the western Dutch coast are less dissipative, steeper, with a higher mean grain size; the species diversity and abundance there are lower. Species diversity and abundance on the beaches increase from the high- to the low-water line. The maximum number of species was found between 0 and -1 m relative to the mean tidal level. The abundance peaks just above the mean tidal level, while the biomass reaches a maximum at the mean tidal level.     Species diversity and abundance are low in the surf zone, but increase towards deeper water. Species numbers are high and the abundance is very high in the trough between the two bars.     The relation between the diversity and abundance of macrobenthic species on the one hand, and the sediment composition, water column depth, and position between the bars on the other show a clear pattern of zonation for the beach, surf zone and near-shore: (1 a supralittoral zone with insects and air-breathing crustaceans, (2 a midshore zone, with intertidal species, (3 a lower shore zone, whose species extend into the shallow surf zone, and (4 a zone of sublittoral fauna in the trough between the

  4. Zoning Districts, Countywide Zoning Shapefile, Published in unknown, Cleveland County.

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — This Zoning Districts dataset as of unknown. It is described as 'Countywide Zoning Shapefile'. Data by this publisher are often provided in State Plane coordinate...

  5. Empowerment Zones and Enterprise Districts - MDC_EnterpriseZone

    Data.gov (United States)

    NSGIC GIS Inventory (aka Ramona) — Polygon feature class of Miami Dade County Enterprise Zones. Enterprise Zones are special areas in the county where certain incentives from the State are available...

  6. Twin Convergence Zones

    Science.gov (United States)

    2002-01-01

    NASA's QuikSCAT satellite has confirmed a 30-year old largely unproven theory that there are two areas near the equator where the winds converge year after year and drive ocean circulation south of the equator. By analyzing winds, QuikSCAT has found a year-round southern and northern Intertropical Convergence Zone. This find is important to climate modelers and weather forecasters because it provides more detail on how the oceans and atmosphere interact near the equator. The Intertropical Convergence Zone (ITCZ) is the region that circles the Earth near the equator, where the trade winds of both the Northern and Southern Hemispheres come together. North of the equator, strong sun and warm water of the equator heats the air in the ITCZ, drawing air in from north and south and causing the air to rise. As the air rises it cools, releasing the accumulated moisture in an almost perpetual series of thunderstorms. Satellite data, however, has confirmed that there is an ITCZ north of the equator and a parallel ITCZ south of the equator. Variation in the location of the ITCZ is important to people around the world because it affects the north-south atmospheric circulation, which redistributes energy. It drastically affects rainfall in many equatorial nations, resulting in the wet and dry seasons of the tropics rather than the cold and warm seasons of higher latitudes. Longer term changes in the ITCZ can result in severe droughts or flooding in nearby areas. 'The double ITCZ is usually only identified in the Pacific and Atlantic Oceans on a limited and seasonal basis,' said Timothy Liu, of NASA's Jet Propulsion Laboratory and California Institute of Technology, Pasadena, Calif., and lead researcher on the project. In the eastern Pacific Ocean, the southern ITCZ is usually seen springtime. In the western Atlantic Ocean, the southern ITCZ was recently clearly identified only in the summertime. However, QuikSCAT's wind data has seen the southern ITCZ in all seasons across the

  7. Occurrence and food habits of the round goby in the profundal zone of southwestern Lake Ontario

    Science.gov (United States)

    Walsh, M.G.; Dittman, D.E.; O'Gorman, R.

    2007-01-01

    Little is known about the ecology of round goby (Neogobius melanostomus), an invasive benthic fish, in the profundal zone of the Great Lakes. In April 2002–2005 we caught increasing numbers of round gobies with a bottom trawl in the 45–150 m depth range of southwestern Lake Ontario. In 2005, we examined gut contents of 30 round gobies from each of three depths, 55, 95, and 130 m, and qualitatively compared gut contents with density of benthic invertebrates determined by Ponar grabs. Round goby guts contained mostly Dreissena spp. and opposum shrimp, Mysis relicta (Mysis); the frequency of occurrence of dreissenids in guts decreased with depth, whereas the frequency of occurrence of Mysis in guts increased with depth. Abundance of these invertebrates in the environment followed the same pattern, although dreissenids of optimum edible size (3–12 mm) were still abundant (1,373/m2) at 130 m, where round gobies primarily consumed Mysis, suggesting that round gobies may switch from dreissenids to more profitable prey when it is available. Other food items were ostracods and fish, with ostracods generally eaten by smaller round gobies and fish eaten by larger round gobies. Occurrence and increasing abundance of round gobies in the profundal zone and predation on Mysis by round goby could have far-reaching consequences for the Lake Ontario fish community.

  8. Utilisation of intensive foraging zones by female Australian fur seals.

    Directory of Open Access Journals (Sweden)

    Andrew J Hoskins

    Full Text Available Within a heterogeneous environment, animals must efficiently locate and utilise foraging patches. One way animals can achieve this is by increasing residency times in areas where foraging success is highest (area-restricted search. For air-breathing diving predators, increased patch residency times can be achieved by altering both surface movements and diving patterns. The current study aimed to spatially identify the areas where female Australian fur seals allocated the most foraging effort, while simultaneously determining the behavioural changes that occur when they increase their foraging intensity. To achieve this, foraging behaviour was successfully recorded with a FastLoc GPS logger and dive behaviour recorder from 29 individual females provisioning pups. Females travelled an average of 118 ± 50 km from their colony during foraging trips that lasted 7.3 ± 3.4 days. Comparison of two methods for calculating foraging intensity (first-passage time and first-passage time modified to include diving behaviour determined that, due to extended surface intervals where individuals did not travel, inclusion of diving behaviour into foraging analyses was important for this species. Foraging intensity 'hot spots' were found to exist in a mosaic of patches within the Bass Basin, primarily to the south-west of the colony. However, the composition of benthic habitat being targeted remains unclear. When increasing their foraging intensity, individuals tended to perform dives around 148 s or greater, with descent/ascent rates of approximately 1.9 m•s-1 or greater and reduced postdive durations. This suggests individuals were maximising their time within the benthic foraging zone. Furthermore, individuals increased tortuosity and decreased travel speeds while at the surface to maximise their time within a foraging location. These results suggest Australian fur seals will modify both surface movements and diving behaviour to maximise their time within a

  9. Physical controls of oxygen fluxes at pelagic and benthic oxyclines in a lake

    DEFF Research Database (Denmark)

    Kreling, Julika; Bravidor, Jenny; McGinnis, Daniel F.;

    2014-01-01

    We compared oxygen fluxes measured simultaneously at the pelagic and benthic oxycline in a lake and analyze their relation to hydrodynamic forcing conditions. While the mean oxygen fluxes did not differ significantly among both sites, the fluxes were highly variable in time. Short energetic perio...

  10. Spatial and temporal influences of environmental conditions on benthic macroinvertebrates in northeast Lake Jesup, central Florida

    Czech Academy of Sciences Publication Activity Database

    Ali, A.; Lobinske, R. J.; Frouz, Jan; Leckel Jr., R. J.

    2003-01-01

    Roč. 66, č. 2 (2003), s. 69-83. ISSN 0098-4590 Grant ostatní: St. Johns River Water Management District(US) 96G345 Institutional research plan: CEZ:AV0Z6066911 Keywords : benthic invertebrates * community * Canonical Correspondence Analysis Subject RIV: EH - Ecology, Behaviour

  11. Application of a Eutrophic Condition Index to Benthic Macroalgal Accumulation in Pacific Northwest Estuaries

    Science.gov (United States)

    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...

  12. Relationships between lake water chemistry and benthic macroinvertebrates in the Athabasca Oil Sands Region, Alberta

    Directory of Open Access Journals (Sweden)

    Keith M. SOMERS

    2010-08-01

    Full Text Available Sulphur and nitrogen emissions in the Athabasca Oil Sands Region (AOSR are a threat to regional lentic ecosystems. Benthic macroinvertebrates have been used successfully elsewhere to monitor the impacts of acid emissions on water bodies and the opportunity exists to implement a regional lentic biomonitoring program in the AOSR. Metrics are often used to assess the impacts of anthropogenic stressors because they describe biological conditions through a variety of measures. The selection of appropriate metrics is an integral component of any biomonitoring program and it depends on the in situ relationships between water chemistry and benthic macroinvertebrates. In order to establish these relationships we compared lake water chemistry parameters with benthic macroinvertebrate communities and metric scores from 32 lakes in the AOSR through Redundancy Analyses. Lake acidity correlates positively with Hyallelidae and negatively with Chironomidae and Oligochaeta while dissolved organic carbon is also an important determinant of benthic macroinvertebrate community composition. A number of metrics were strongly correlated with lake acidity and the following compositional metrics proved to be the most suitable for monitoring acidification in the AOSR: % Diptera, % Oligochaeta, % EPT, Total Ephemeroptera and Total Trichoptera.

  13. Subtidal benthic macrofauna of the Mangalore Coast, west coast of India

    Digital Repository Service at National Institute of Oceanography (India)

    Gopalakrishnan, T.C.; Nair, K.K.C.

    and New Mangalore Port appeared to be more productive compared to the suratkal area in the north. The striking difference noticed was the shift in the benthic production from the 5 m contour. In all the earlier workd 5 m contour line was found to be most...

  14. Water Quality Assessment Using Benthic Macroinvertebrates in a Periurban Stream (Cameroon)

    OpenAIRE

    Foto Menbohan S; Tchakonte S; Ajeagah Gideon A; Zebaze Togouet S. H; Bilong Bilong C.F.; Njiné T

    2013-01-01

    In order to assess the water quality of Nga stream, the right tributary of Mefou, physicochemical variables were coupled to benthic macroinvertebrates communities. Physicochemical results revealed a good health status of the Nga stream, with significant differences of conductivity observed between stations and months (P

  15. Successional trends of the benthic macroinvertebrate community in a new southeastern cooling reservoir

    International Nuclear Information System (INIS)

    Lakes created by river impoundments provide new lentic habitats for benthic macroinvertebrates. As new lakes age, benthic macroinvertebrate succession proceeds as first colonizers are replaced and stable populations eventually become established. L Lake, a 400 ha reservoir, was constructed in 1985 on the Department of Energy's Savannah River Site in South Carolina to receive heated effluent from a nuclear production reactor. Benthic macroinvertebrates were collected in L Lake with a ponar grab sampler at 2 and 4 meters at 10 locations in 5 lake regions. Monthly collections were made from 1986 through 1989. Annual average densities of benthic macroinvertebrates increased substantially during the study (ranging from 3955.5--4471.6 organisms/m2 in 1986 to 8948.1--11,694.1 organisms/m2 in 1988). Annual mean biomass also increased (ranging from 0.749--0.907g AFDM/m2 in 1986 to 2074--11,322 g AFDM/m2 in 1988). Mean annual taxa richness ranged from 9.3--12.2 per ponar in 1986 to 11.8--15.3 per ponar in 1988. Some early colonizers (Chironomidae: Chironomini) dominated throughout the study (ranging from 60.3--79.1% of all organisms). Other chironomids (Tanytarsini and Tanypodinae) declined while slower colonizers (oligochaetes and nematodes) generally increased from 1986 through 1988. The increases in macroinvertebrate density, biomass and changes in community composition observed are typical of early reservoir succession. 14 refs., 12 figs., 1 tab

  16. Benthic macroinvertebrates in lake ecological assessment: A review of methods, intercalibration and practical recommendations.

    Science.gov (United States)

    Poikane, Sandra; Johnson, Richard K; Sandin, Leonard; Schartau, Ann Kristin; Solimini, Angelo G; Urbanič, Gorazd; Arbačiauskas, Kęstutis; Aroviita, Jukka; Gabriels, Wim; Miler, Oliver; Pusch, Martin T; Timm, Henn; Böhmer, Jürgen

    2016-02-01

    Legislation in Europe has been adopted to determine and improve the ecological integrity of inland and coastal waters. Assessment is based on four biotic groups, including benthic macroinvertebrate communities. For lakes, benthic invertebrates have been recognized as one of the most difficult organism groups to use in ecological assessment, and hitherto their use in ecological assessment has been limited. In this study, we review and intercalibrate 13 benthic invertebrate-based tools across Europe. These assessment tools address different human impacts: acidification (3 methods), eutrophication (3 methods), morphological alterations (2 methods), and a combination of the last two (5 methods). For intercalibration, the methods were grouped into four intercalibration groups, according to the habitat sampled and putative pressure. Boundaries of the 'good ecological status' were compared and harmonized using direct or indirect comparison approaches. To enable indirect comparison of the methods, three common pressure indices and two common biological multimetric indices were developed for larger geographical areas. Additionally, we identified the best-performing methods based on their responsiveness to different human impacts. Based on these experiences, we provide practical recommendations for the development and harmonization of benthic invertebrate assessment methods in lakes and similar habitats. PMID:26580734

  17. Carbon and nitrogen flows through the benthic food web of a photic subtidal sandy sediment

    NARCIS (Netherlands)

    Evrard, V.P.E.; Soetaert, K.E.R.; Heip, C.H.R.; Huettel, M.; Xenopoulos, M.A.; Middelburg, J.J.

    2010-01-01

    Carbon and nitrogen flows within the food web of a subtidal sandy sediment were studied using stable isotope natural abundances and tracer addition. Natural abundances of 13C and 15N stable isotopes of the consumers and their potential benthic and pelagic resources were measured. δ13C data revealed

  18. Benthic foraminiferal fauna turnover at 2.1 Ma in the northern South China Sea

    Institute of Scientific and Technical Information of China (English)

    HUANG BaoQi; JIAN ZhiMin; WANG PinXian

    2007-01-01

    Quantitative analysis of benthic foraminifera from ODP Site 1146 in the northern South China Sea (SCS)shows that abundance of Bulimina alazanensis, sometimes up to about 90%, decreased gradually since 3.2 Ma, especially at 2.1 Ma. Abundance of other benthic foraminiferal species, Globobulimina subglobosa and Cibicidoides wuellerstorfi, increased after 2.1 Ma. Comparison with changes in oxygen and carbon isotopes of planktonic and benthic foraminifera shows that high abundance values of B.alazanensis corresponded with lower values of oxygen isotope, but for carbon isotope, high values of the species were consistent with heavier carbon Isotope of benthic foraminifera and lighter carbon isotope of planktonic foraminifera, respectively, and vice versa. Considering factors such as uplift of Bashi Strait, expansion of the North Hemisphere Glaciation, strengthening of East Asian winter monsoon and variations in oxygen and carbon isotope of foraminifera, changes of B. alazanensis in ODP Site 1146 suggest that the source of deep water masses of the northern South China Sea changed from the warm Pacific deep water with high oxygen content to Pacific Intermediate water with Iow oxygen content at 2.1 Ma. In addition, the strengthened East Asian winter monsoon resulted in increased primary productivity, high nutrient and suboxic bottom water. Variations in species of B. alazanensis seemed to be unable to tolerate environmental stress induced by deep water masses and productivity changes.

  19. Spatial scale and the diversity of benthic cyanobacteria and diatoms in a salina

    DEFF Research Database (Denmark)

    Nübel, U.; Garcia-Pichel, F.; Kühl, Michael;

    1999-01-01

    We characterized the richness of benthic cyanobacteria and diatoms in a salina system using traditional and molecular biological methods. After determining the different morphotypes and 16S rRNA genes present in various localities within this hypersaline system, an analysis of the increase...

  20. Application of Multiple Index Development Approaches to Benthic Invertebrate Data from the Virginian Biogeographic Province, USA

    Science.gov (United States)

    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...

  1. Nearshore marine benthic invertebrates moving north along the U.S. Atlantic coast

    Science.gov (United States)

    Numerous species have shifted their ranges north in response to global warming. We examined 21 years (1990-2010) of marine benthic invertebrate data from the National Coastal Assessment’s monitoring of nearshore waters along the US Atlantic coast. Data came from three bioge...

  2. Length-weight relationships of 216 North Sea benthic invertebrates and fish

    NARCIS (Netherlands)

    Robinson, L.; Greenstreet, S.P.R.; Reiss, H.; Callaway, R.; Craeymeersch, J.A.M.; Boois, de I.J.

    2010-01-01

    Size-based analyses of marine animals are increasingly used to improve understanding of community structure and function. However, the resources required to record individual body weights for benthic animals, where the number of individuals can reach several thousand in a square metre, are often pro

  3. From Greenland to green lakes: Cultural eutrophication and the loss of benthic pathways in lakes

    DEFF Research Database (Denmark)

    Vadeboncoeur, Y.; Jeppesen, E.; Zanden, M. J. V.;

    2003-01-01

    with TP . 100 mg m23, phytoplankton were responsible for nearly 100% of primary production. Benthic contributions ranged from 5 to 80% depending on morphometry and littoral habitat composition in lakes with intermediate phosphorus concentrations. Thus, eutrophication was characterized by a switch from...

  4. Coral reef condition and benthic sedimentation threat in four regions of south Puerto Rico

    Science.gov (United States)

    Scleractinian corals, gorgonian octocorals, sponges and fishes were assessed near the cities of LaParguera, Guánica, Guayanilla, and Jobos along the southern coast of Puerto Rico in November – December 2010. Survey sites were targeted near areas with varying benthic...

  5. Recent benthic foraminifera from the Caribbean continental slope and shelf off west of Colombia

    Science.gov (United States)

    Fiorini, Flavia

    2015-07-01

    A quantitative benthic foraminiferal analysis was conducted on 30 sea-floor sediment samples distributed along the continental slope and shelf in Fuerte Area (Colombian Caribbean), between 39 and 2469 m water depth. The aims of the research were to provide data on the distribution of southwestern Caribbean Recent benthic foraminifera, to estimate changes in the foraminiferal distribution related to the bathymetry and the characteristics of the substrate, to define a data-bank on distribution of recent tropical benthic foraminifera from the southwestern Caribbean, to provide reference on foraminiferal distribution that can be used in bathymetric reconstructions of ancient environments. Three different assemblages corresponding to three different environments were identified by cluster analysis. Assemblage A, characterized by variable percentages of porcellaneous, hyaline and agglutinated benthic foraminifera indicative of shelf environments. Assemblage B, dominated by calcareous hyaline foraminifera mainly composed of infaunal foraminifera corresponding to upper bathyal, marine conditions. Assemblage C, composed by agglutinated and calcareous hyaline foraminifera characteristic of normal deep-water marine environments.

  6. Benthic macroinvertebrate surveys in Chequamegon Bay in support of invasive species early detection research

    Science.gov (United States)

    This presentation describes the impetus and approach for MED invasive species early detection research generally and presents preliminary results concerning benthic composition and non-native species found in the 2013 Chequamegon Bay survey. The audience is a group of researchers...

  7. Shedding light on DOC release by benthic primary producers and its consumption by bioeroding sponges

    NARCIS (Netherlands)

    Müller, Benjamin

    2015-01-01

    The effect of light on dissolved organic carbon (DOC) release of benthic primary producers (BPPs) was investigated on the coral reefs of Curaçao. Incubation experiments revealed a positive relation between the DOC release of four Caribbean reef algae (Cladophora sp., Dictyota menstrualis, Lobophora

  8. 2010 NCCA oligochaete trophic index results to inform benthic index development for the Great Lakes

    Science.gov (United States)

    Over 400 sites were sampled in the nearshore of the U.S. Great Lakes during the National Coastal Condition Assessment (NCCA) field survey in summer 2010. To assess benthic ecological condition, 393 PONARs were attempted, and collected macroinvertebrates were identified and enume...

  9. Bioturbation of sediments by benthic macroinvertebrates and fish and its implication for pond ecosystems: a review

    Czech Academy of Sciences Publication Activity Database

    Adámek, Z.; Maršálek, Blahoslav

    2013-01-01

    Roč. 21, č. 1 (2013), s. 1-17. ISSN 0967-6120 R&D Projects: GA MPO FR-TI3/196 Institutional research plan: CEZ:AV0Z60050516 Institutional support: RVO:67985939 Keywords : benthic macroinverttebrates * benthivorous fish * bottom- water interface * nutrient cycling * pond management Subject RIV: EF - Botanics Impact factor: 0.960, year: 2013

  10. Organic matter degradation drives benthic cyanobacterial mat abundance on caribbean coral reefs

    NARCIS (Netherlands)

    Brocke, Hannah J.; Polerecky, Lubos; De Beer, Dirk; Weber, Miriam; Claudet, Joachim; Nugues, Maggy M.

    2015-01-01

    Benthic cyanobacterial mats (BCMs) are impacting coral reefs worldwide. However, the factors and mechanisms driving their proliferation are unclear. We conducted a multi-year survey around the Caribbean island of Curaçao, which revealed highest BCM abundance on sheltered reefs close to urbanised are

  11. Determining the impacts of trawling on benthic function in European waters : a biological traits approach

    DEFF Research Database (Denmark)

    Bolam, Stefan; Kenny, Andrew; Garcia, Clement;

    on benthic ecosystem functioning over much larger spatial scales than previously undertaken. Biological traits information from 887 stations across European waters (Norwegian, UK, Belgian, Dutch, Danish waters, the Mediterranean and Black Sea) were analysed to: i) quantify the relationships between infaunal...

  12. Eutrophication and Hypoxia Degrade Ecosystem Functions and Services of Narragansett Bay Benthic Communities

    Science.gov (United States)

    Excessive input of nitrogen to estuaries and coastal waters leads to eutrophication; the resulting organic matter over-enrichment of the sediments and seasonal hypoxia of the bottom water have well-known deleterious effects on benthic community biodiversity, abundance, and biomas...

  13. Benthic fluxes in a tropical estuary and their role in the ecosystem

    Digital Repository Service at National Institute of Oceanography (India)

    Pratihary, A.K.; Naqvi, S.W.A.; Naik, H.; Thorat, B.R.; Narvenkar, G.; Manjunatha, B.R.; Rao, V.P.

    ) sup(4-) and acted as a net sink of combined N because of the high rate of benthic denitrification as it could remove 22% of riverine DIN influx thereby protecting the eco system from eutrophication and consequent degradation. The estuarine sediment...

  14. The benthic hydroid fauna of the Chafarinas Islands (Alborán Sea, western Mediterranean)

    NARCIS (Netherlands)

    Peña Cantero, A.L.; García Carrascosa, A.M.

    2002-01-01

    The benthic hydroid fauna of the Chafarinas Islands (Western Mediterranean), collected during a survey in the summer of 1991, has been studied. A total of 86 species, 20 athecate hydroids and 66 thecate hydroids, has been recorded. For every species, the synonymy, a survey of the material studied an

  15. The impact of artisanal fishery on a tropical intertidal benthic fish community

    NARCIS (Netherlands)

    de Boer, WF; van Schie, AMP; Jocene, DF; Mabote, ABP; Guissamulo, A

    2001-01-01

    We examined the benthic fishes and artisanal fishery in the intertidal flats of Inhaca Island, Mozambique. Results of a questionnaire indicated that catches had decreased, and that piscivorous fish have disappeared. Results of a catch sampling study indicated that current catch rates are low, <2 kg

  16. Benthic Macro Invertebrate Fauna and Physico-chemical Parameters in Okpoka Creek Sediments, Niger Delta, Nigeria

    OpenAIRE

    J.F.N. Abowei

    2009-01-01

    The benthic macro invertebrate fauna and physico-chemical parameters in Okpoka creek sedimentswas studied for a period of one year. A total of nineteen (19) species(Ophidonais serpentina, Arenicola marina,Eunice harassi, Marphysa sanguinea, Capitella capitata, Notomastus latrella, Notomastus tenuis, Glyceracapitata, Glycera convoluta, Nereis diversicolor, Nereis pelagica, Nereis virens, Nephthys hombergi,Nototropis swamidami, Cliberanus cooci, Iphinoe tripanosa, Chironomus ablabiesmia, Tellin...

  17. Cape Verde Frontal Zone

    OpenAIRE

    Zenk, Walter; Klein, Birgit; Schröder, Michael

    1991-01-01

    The term Cape Verde Frontal Zone is introduced to characterize the southeastern corner of the subtropical gyre circulation in the North Atlantic Ocean far west of the upwelling area off the Mauretanean shelf. Two water mass fronts, one overlying the other, are identified with a quasi-synoptic set of CTD-OZ and nutrient data from November 1986. In the warm water sphere we encounter North and South Atlantic Central Water (NACWISACW) superimposed on extensions of Mediterranean outflow and Antarc...

  18. The truth is out there: measured, calculated and modelled benthic fluxes.

    Science.gov (United States)

    Pakhomova, Svetlana; Protsenko, Elizaveta

    2016-04-01

    In a modern Earth science there is a great importance of understanding the processes, forming the benthic fluxes as one of element sources or sinks to or from the water body, which affects the elements balance in the water system. There are several ways to assess benthic fluxes and here we try to compare the results obtained by chamber experiments, calculated from porewater distributions and simulated with model. Benthic fluxes of dissolved elements (oxygen, nitrogen species, phosphate, silicate, alkalinity, iron and manganese species) were studied in the Baltic and Black Seas from 2000 to 2005. Fluxes were measured in situ using chamber incubations (Jch) and at the same time sediment cores were collected to assess the porewater distribution at different depths to calculate diffusive fluxes (Jpw). Model study was carried out with benthic-pelagic biogeochemical model BROM (O-N-P-Si-C-S-Mn-Fe redox model). It was applied to simulate biogeochemical structure of the water column and upper sediment and to assess the vertical fluxes (Jmd). By the behaviour at the water-sediment interface all studied elements can be divided into three groups: (1) elements which benthic fluxes are determined by the concentrations gradient only (Si, Mn), (2) elements which fluxes depend on redox conditions in the bottom water (Fe, PO4, NH4), and (3) elements which fluxes are strongly connected with organic matter fate (O2, Alk, NH4). For the first group it was found that measured fluxes are always higher than calculated diffusive fluxes (1.5changing redox conditions some processes in the bottom water and/or on the sediment surface (oxidation, adsorption, particles dissolution, etc.) are faster than diffusion and play an important role in the benthic flux formation for these elements. For the third group measured fluxes could be often overestimated, especially for coastal shallow stations, up to 50%, because of intensive decomposition of OM and/or organisms respiration in the isolated bottom

  19. A newly developed dispersal metric indicates the succession of benthic invertebrates in restored rivers.

    Science.gov (United States)

    Li, Fengqing; Sundermann, Andrea; Stoll, Stefan; Haase, Peter

    2016-11-01

    Dispersal capacity plays a fundamental role in the riverine benthic invertebrate colonization of new habitats that emerges following flash floods or restoration. However, an appropriate measure of dispersal capacity for benthic invertebrates is still lacking. The dispersal of benthic invertebrates occurs mainly during the aquatic (larval) and aerial (adult) life stages, and the dispersal of each stage can be further subdivided into active and passive modes. Based on these four possible dispersal modes, we first developed a metric (which is very similar to the well-known and widely used saprobic index) to estimate the dispersal capacity for 802 benthic invertebrate taxa by incorporating a weight for each mode. Second, we tested this metric using benthic invertebrate community data from a) 23 large restored river sites with substantial improvements of river bottom habitats dating back 1 to 10years, b) 23 unrestored sites very close to the restored sites, and c) 298 adjacent surrounding sites (mean±standard deviation: 13.0±9.5 per site) within a distance of up to 5km for each restored site in the low mountain and lowland areas of Germany. We hypothesize that our metric will reflect the temporal succession process of benthic invertebrate communities colonizing the restored sites, whereas no temporal changes are expected in the unrestored and surrounding sites. By applying our metric to these three river treatment categories, we found that the average dispersal capacity of benthic invertebrate communities in the restored sites significantly decreased in the early years following restoration, whereas there were no changes in either the unrestored or the surrounding sites. After all taxa had been divided into quartiles representing weak to strong dispersers, this pattern became even more obvious; strong dispersers colonized the restored sites during the first year after restoration and then significantly decreased over time, whereas weak dispersers continued to increase

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

    Science.gov (United States)

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

    2014-12-01

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

  1. Response of invertebrates from the hyporheic zone of chalk rivers to eutrophication and land use.

    Science.gov (United States)

    Pacioglu, Octavian; Moldovan, Oana Teodora

    2016-03-01

    Whereas the response of lotic benthic macroinvertebrates to different environmental stressors is a widespread practice nowadays in assessing the water and habitat quality, the use of hyporheic zone invertebrates is still in its infancy. In this study, classification and regression trees analysis were employed in order to assess the ecological requirements and the potential as bioindicators for the hyporheic zone invertebrates inhabiting four lowland chalk rivers (south England) with contrasting eutrophication levels (based on surface nitrate concentrations) and magnitude of land use (based on percentage of fine sediments load and median interstitial space). Samples of fauna, water and sediment were sampled twice, during low (summer) and high (winter) groundwater level, at depths of 20 and 35 cm. Certain groups of invertebrates (Glossosomatidae and Psychomyiidae caddisflies, and riffle beetles) proved to be good indicators of rural catchments, moderately eutrophic and with high fine sediment load. A diverse community dominated by microcrustaceans (copepods and ostracods) were found as good indicators of highly eutrophic urban streams, with moderate-high fine sediment load. However, the use of other taxonomic groups (e.g. chironomids, oligochaetes, nematodes, water mites and the amphipod Gammarus pulex), very widespread in the hyporheic zone of all sampled rivers, is of limited use because of their high tolerance to the analysed stressors. We recommend the use of certain taxonomic groups (comprising both meiofauna and macroinvertebrates) dwelling in the chalk hyporheic zone as indicators of eutrophication and colmation and, along with routine benthic sampling protocols, for a more comprehensive water and habitat quality assessment of chalk rivers. PMID:26531711

  2. Radiant zone heated particulate filter

    Science.gov (United States)

    Gonze, Eugene V [Pinckney, MI

    2011-12-27

    A system includes a particulate matter (PM) filter including an upstream end for receiving exhaust gas and a downstream end. A radiant zoned heater includes N zones, where N is an integer greater than one, wherein each of the N zones includes M sub-zones, where M is an integer greater than or equal to one. A control module selectively activates at least a selected one of the N zones to initiate regeneration in downstream portions of the PM filter from the one of the N zones, restricts exhaust gas flow in a portion of the PM filter that corresponds to the selected one of the N zones, and deactivates non-selected ones of the N zones.

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

    Science.gov (United States)

    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.

  4. Cyanobacteria-derived nitrogen uptake by benthic invertebrates in Lake Taihu: a mesocosm study using 15N labeling

    Directory of Open Access Journals (Sweden)

    Yu J.

    2014-01-01

    Full Text Available Eutrophication of lakes can lead to dominance by cyanobacteria, which are hardly used by zooplankton due to their low nutrition value. However, sedimented cyanobacterial detritus may be a useful source for benthic invertebrates. We studied the Microcystis-derived nitrogen incorporation in benthic invertebrates in Lake Taihu using stable isotopic nitrogen (15N as a tracer. The δ15N of all organisms increased significantly with time after addition of the labeled Microcystis detritus. δ15N values of POM and periphyton peaked earlier than for benthic invertebrates, and the maximum levels were also higher than bivalves, snails and worms (Limnodrilus spp.. Among benthic invertebrates, Radix swinhoei peaked later than other invertebrates, but the maximum level and the excess 15N of the last sampling day were higher. At the end of the experiment, approximately 70% of the added 15N was retained in the benthic food web, while only a small fraction (less than 1% of the added detritus 15N occurred in the pelagic food web. Our results suggest that nitrogen from cyanobacteria can be incorporated more in benthic than pelagic food webs and cyanobacterial blooms may contribute to the development of benthic animals.

  5. Blasting of broken marble zones

    OpenAIRE

    Dambov, Risto; Stojceski, Igor; Dambov, Ilija

    2015-01-01

    On receipt of marble blocks appear deformed zones with presence of cracks and other deformities and very small cracks with different azimuth in the rocky massif. The fastest and economical way to bring this zone are removed by applying the methods of blasting. Before blasting, these tables - zones are limited by the block, making the cuts with diamond wire because explosive action may cause of surrounding quality marble blocks. Keywords: blasting, crashed zones, cracks, marble ...

  6. Differential bioaccumulation of potentially toxic elements in benthic and pelagic food chains in Lake Baikal.

    Science.gov (United States)

    Ciesielski, Tomasz M; Pastukhov, Mikhail V; Leeves, Sara A; Farkas, Julia; Lierhagen, Syverin; Poletaeva, Vera I; Jenssen, Bjørn M

    2016-08-01

    Lake Baikal is located in eastern Siberia in the center of a vast mountain region. Even though the lake is regarded as a unique and pristine ecosystem, there are existing sources of anthropogenic pollution to the lake. In this study, the concentrations of the potentially toxic trace elements As, Cd, Pb, Hg, and Se were analyzed in water, plankton, invertebrates, and fish from riverine and pelagic influenced sites in Lake Baikal. Concentrations of Cd, Hg, Pb and Se in Lake Baikal water and biota were low, while concentrations of As were similar or slightly higher compared to in other freshwater ecosystems. The bioaccumulation potential of the trace elements in both the pelagic and the benthic ecosystems differed between the Selenga Shallows (riverine influence) and the Listvenichnyĭ Bay (pelagic influence). Despite the one order of magnitude higher water concentrations of Pb in the Selenga Shallows, Pb concentrations were significantly higher in both pelagic and benthic fish from the Listvenichnyĭ Bay. A similar trend was observed for Cd, Hg, and Se. The identified enhanced bioavailability of contaminants in the pelagic influenced Listvenichnyĭ Bay may be attributed to a lower abundance of natural ligands for contaminant complexation. Hg was found to biomagnify in both benthic and pelagic Baikal food chains, while As, Cd, and Pb were biodiluted. At both locations, Hg concentrations were around seven times higher in benthic than in pelagic fish, while pelagic fish had two times higher As concentrations compared to benthic fish. The calculated Se/Hg molar ratios revealed that, even though Lake Baikal is located in a Se-deficient region, Se is still present in excess over Hg and therefore the probability of Hg induced toxicity in the endemic fish species of Lake Baikal is assumed to be low. PMID:27130338

  7. Saturated Zone Colloid Transport

    International Nuclear Information System (INIS)

    This scientific analysis provides retardation factors for colloids transporting in the saturated zone (SZ) and the unsaturated zone (UZ). These retardation factors represent the reversible chemical and physical filtration of colloids in the SZ. The value of the colloid retardation factor, Rcol is dependent on several factors, such as colloid size, colloid type, and geochemical conditions (e.g., pH, Eh, and ionic strength). These factors are folded into the distributions of Rcol that have been developed from field and experimental data collected under varying geochemical conditions with different colloid types and sizes. Attachment rate constants, katt, and detachment rate constants, kdet, of colloids to the fracture surface have been measured for the fractured volcanics, and separate Rcol uncertainty distributions have been developed for attachment and detachment to clastic material and mineral grains in the alluvium. Radionuclides such as plutonium and americium sorb mostly (90 to 99 percent) irreversibly to colloids (BSC 2004 [DIRS 170025], Section 6.3.3.2). The colloid retardation factors developed in this analysis are needed to simulate the transport of radionuclides that are irreversibly sorbed onto colloids; this transport is discussed in the model report ''Site-Scale Saturated Zone Transport'' (BSC 2004 [DIRS 170036]). Although it is not exclusive to any particular radionuclide release scenario, this scientific analysis especially addresses those scenarios pertaining to evidence from waste-degradation experiments, which indicate that plutonium and americium may be irreversibly attached to colloids for the time scales of interest. A section of this report will also discuss the validity of using microspheres as analogs to colloids in some of the lab and field experiments used to obtain the colloid retardation factors. In addition, a small fraction of colloids travels with the groundwater without any significant retardation. Radionuclides irreversibly sorbed

  8. Morphogenetic role of F-actin meshwork in chamber formation: immunolabeling results from symbiont bearing benthic foraminifera

    Science.gov (United States)

    Tyszka, Jaroslaw; Raitzsch, Markus; Bijma, Jelle; Höher, Nicole; Bickmeyer, Ulf; Rivera-Ingraham, Georginia; Topa, Paweł; Kaczmarek, Karina; Mewes, Antje; Bowser, Samuel; Travis, Jeffrey

    2015-04-01

    Foraminifera are excellent tracers of palaeoceanographic conditions recorded in their shell (test) morphology and chemical composition. Understanding foraminiferal morphology controlled by chamberwise growth can be reduced to processes of chamber formation. However, little is known about how foraminifera control the shape of the chamber wall to be biosynthesized and precipitated. Searching for fundamental morphogenetic features involved in biomineralization, we focused on foraminifers, which belong to the class Globothalamea. The most critical condition to run experiments was to have convenient access to early stages of chamber formation in any species of cultured benthic foraminifers. We have tested small foraminifers collected from the tidal flats of the North Sea. All species, including Ammonia, Haynesina, and Elphidium, turned out to be unsuitable due to their reproduction seasonality and/or unpredictability. The problem was solved by using symbiont bearing Amphistegina lessonii cultured in small aquaria. In well treated cultures, such foraminifera often reproduce on a glass wall surface, serving as a continuous source of juveniles. They tend to regularly construct chambers. Another important point is that symbiont bearing foraminifers usually do not construct opaque protective cysts from detritus that disturb observations. All these features facilitate immunolabeling experiments observed under confocal microscopy. Therefore, for the first time, we managed to label cytoskeleton proteins during the chamber formation in Foraminifera. The results show that the shape of chamber is predefined by a meshwork of F-actin, which acts as a dynamic organic scaffold most likely responsible for distribution and docking of biomineralizing molecules (glycoproteins). The F-actin meshwork interacts with microtubules and all associated proteins, which are involved in the morphogenesis of biomineralized structures. Foraminifera, like other eukaryotic cells, can form active

  9. Food web architecture and basal resources interact to determine biomass and stoichiometric cascades along a benthic food web.

    Directory of Open Access Journals (Sweden)

    Rafael D Guariento

    Full Text Available Understanding the effects of predators and resources on primary producers has been a major focus of interest in ecology. Within this context, the trophic cascade concept especially concerning the pelagic zone of lakes has been the focus of the majority of these studies. However, littoral food webs could be especially interesting because base trophic levels may be strongly regulated by consumers and prone to be light limited. In this study, the availability of nutrients and light and the presence of an omnivorous fish (Hyphessobrycon bifasciatus were manipulated in enclosures placed in a humic coastal lagoon (Cabiúnas Lagoon, Macaé - RJ to evaluate the individual and interactive effects of resource availability (nutrients and light and food web configuration on the biomass and stoichiometry of periphyton and benthic grazers. Our findings suggest that light and nutrients interact to determine periphyton biomass and stoichiometry, which propagates to the consumer level. We observed a positive effect of the availability of nutrients on periphytic biomass and grazers' biomass, as well as a reduction of periphytic C∶N∶P ratios and an increase of grazers' N and P content. Low light availability constrained the propagation of nutrient effects on periphyton biomass and induced higher periphytic C∶N∶P ratios. The effects of fish presence strongly interacted with resource availability. In general, a positive effect of fish presence was observed for the total biomass of periphyton and grazer's biomass, especially with high resource availability, but the opposite was found for periphytic autotrophic biomass. Fish also had a significant effect on periphyton stoichiometry, but no effect was observed on grazers' stoichiometric ratios. In summary, we observed that the indirect effect of fish predation on periphyton biomass might be dependent on multiple resources and periphyton nutrient stoichiometric variation can affect consumers' stoichiometry.

  10. Parapapillary atrophy: histological gamma zone and delta zone.

    Directory of Open Access Journals (Sweden)

    Jost B Jonas

    Full Text Available BACKGROUND: To examine histomorphometrically the parapapillary region in human eyes. METHODOLOGY/PRINCIPAL FINDINGS: The histomorphometric study included 65 human globes (axial length:21-37 mm. On anterior-posterior histological sections, we measured the distance Bruch's membrane end (BME-optic nerve margin ("Gamma zone", BME-retinal pigment epithelium (RPE ("Beta zone", BME-beginning of non-occluded choriocapillaris, and BME-beginning of photoreceptor layer. "Delta zone" was defined as part of gamma zone in which blood vessels of at least 50 µm diameter were not present over a length of >300 µm. Beta zone (mean length:0.35±0.52 mm was significantly (P = 0.01 larger in the glaucoma group than in the non-glaucomatous group. It was not significantly (P = 0.28 associated with axial length. Beta zone was significantly (P = 0.004 larger than the region with occluded choriocapillaris. Gamma zone (mean length:0.63±1.25 mm was associated with axial length (P50 µm diameter within gamma zone was present only in highly axially elongated globes and was not related with glaucoma. Beta zone (Bruch's membrane without RPE was correlated with glaucoma but not with globe elongation. Since the region with occluded choriocapillaris was smaller than beta zone, complete loss of RPE may have occurred before complete choriocapillaris closure.

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

    Science.gov (United States)

    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

  12. The truth is out there: measured, calculated and modelled benthic fluxes.

    Science.gov (United States)

    Pakhomova, Svetlana; Protsenko, Elizaveta

    2016-04-01

    In a modern Earth science there is a great importance of understanding the processes, forming the benthic fluxes as one of element sources or sinks to or from the water body, which affects the elements balance in the water system. There are several ways to assess benthic fluxes and here we try to compare the results obtained by chamber experiments, calculated from porewater distributions and simulated with model. Benthic fluxes of dissolved elements (oxygen, nitrogen species, phosphate, silicate, alkalinity, iron and manganese species) were studied in the Baltic and Black Seas from 2000 to 2005. Fluxes were measured in situ using chamber incubations (Jch) and at the same time sediment cores were collected to assess the porewater distribution at different depths to calculate diffusive fluxes (Jpw). Model study was carried out with benthic-pelagic biogeochemical model BROM (O-N-P-Si-C-S-Mn-Fe redox model). It was applied to simulate biogeochemical structure of the water column and upper sediment and to assess the vertical fluxes (Jmd). By the behaviour at the water-sediment interface all studied elements can be divided into three groups: (1) elements which benthic fluxes are determined by the concentrations gradient only (Si, Mn), (2) elements which fluxes depend on redox conditions in the bottom water (Fe, PO4, NH4), and (3) elements which fluxes are strongly connected with organic matter fate (O2, Alk, NH4). For the first group it was found that measured fluxes are always higher than calculated diffusive fluxes (1.5stations, up to 50%, because of intensive decomposition of OM and/or organisms respiration in the isolated bottom water. Values of benthic fluxes obtained by the BROM model are within the range of magnitudes measured by chamber experiments and calculated from porewater distributions (Jpw < Jmd < Jch). Using the model it is possible estimate the influence of bioturbation on elements exchange at water-sediment interface. Model has a high resolution in the

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

    Science.gov (United States)

    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

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

    Science.gov (United States)

    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

  15. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Rose, American Samoa in 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  16. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Maui, Main Hawaiian Islands in 2010

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  17. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Kingman, Pacific Remote Island Areas in 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  18. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Farallon de Pajaros, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  19. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Aguijan, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  20. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Swains, American Samoa in 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  1. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Ofu & Olosega, American Samoa in 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  2. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Tinian, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  3. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Rota, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  4. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Alamagan, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  5. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at French Frigate, Northwestern Hawaiian Islands in 2010

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  6. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Baker, Pacific Remote Island Areas in 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  7. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Saipan, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  8. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Jarvis, Pacific Remote Island Areas in 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  9. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Kure, Northwestern Hawaiian Islands in 2010

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  10. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Maug, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  11. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Palmyra, Pacific Remote Island Areas in 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  12. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Guguan, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  13. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Sarigan, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  14. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Hawaii, Main Hawaiian Islands in 2010

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  15. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Tutuila, American Samoa in 2012

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  16. Fish, Benthic and Urchin Survey Data from Kahekili Herbivore Fisheries Management Area (HFMA), Maui since 2008 (NCEI Accession 0146683)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Data are summary fish, benthic and urchin data from belt transect surveys conducted by the NOAA Coral Reef Ecosystem Program within the Kahekili Herbivore Fisheries...

  17. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Asuncion, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  18. CRED Rapid Ecological Assessment Line Point Intercept Survey of Benthic Parameter Assessments at Guam, Marianas in 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Line point intercept (LPI) surveys and benthic composition assessments were conducted during Rapid Ecological Assessments (REA) as part of the Pacific Reef...

  19. Baseline assessment of benthic communities of the Flower Garden Banks (2010 - 2013) using technical diving operations: 2011

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — The proposed work develop baseline information on fish and benthic communities within the Flower Garden Banks National Marine Sanctuary (FGBNMS). Surveys will...

  20. Benthic habitat data of Wawaloi and Keei, Kona Coast, Island of Hawaii, August 2004 (NODC Accession 0070530)

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — Transects were made at two locations on the west side of the Island of Hawaii in August 2004 to study the structure and composition of the benthic habitat....