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Joan Enric Cartes - One of the best experts on this subject based on the ideXlab platform.
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trophic relationships in a mediterranean deep sea fish community partition of food resources dietary overlap and connections within the Benthic Boundary Layer
Marine Ecology Progress Series, 2002Co-Authors: Maite Carrasson, Joan Enric CartesAbstract:Food resource partitioning and some trends in the feeding ecology of 13 species of fishes inhabiting the slope of the Catalan Sea (western Mediterranean) were examined. Specimens were collected from 1987 to 1991, using bottom trawls at depths between 1000 and 2250 m. Prey selection was also examined in relation to data collected in the same area on 2 potential prey compartments for fish, the benthopelagic macrofauna —suprabenthos or hyperbenthos— and the megafaunal decapod crustaceans. Thus, the possible connections with prey availability within the Benthic Boundary Layer (BBL) were also analysed. The size of available food resources was the most important factor respon- sible for food resource partitioning, both by depth stratum and season. The importance of the variable predator size is also evidenced. Most of the deep-sea demersal fish species inhabiting the Catalano- Balearic slope often consumed a variety of available resources in their diets, mainly comprising suprabenthos, but also infauna or planktonic prey. Thus, the BBL macrofauna constitute an important part of the available food exploited, with the range of the prey consumed increasing for the largest predators. A significant trend to increase dietary H' values within the depth interval where each spe- cies attained its maximum abundance was observed. Some (positive) prey selection upon certain prey groups was detected depending on the fish species: sharks, Alepocephalus rostratus and Nettastoma melanurum preferentially preyed on decapods, siphonophores and pyrosomids; Polyacanthonotus rissoanus, macrourids, Lepidion lepidion and Cataetyx alleni preyed upon supraBenthic peracarid crustaceans; and only Bathypterois mediterraneus preferentially consumed copepods, the numeri- cally dominant group in the bathyal BBL. Resource partitioning was high among the fish assemblage analysed in relation to the generally low dietary overlap values recorded. Overall, dietary overlap values among fish species decreased with increasing depth.
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dynamics of the bathyal Benthic Boundary Layer in the northwestern mediterranean depth and temporal variations in macrofaunal megafaunal communities and their possible connections within deep sea trophic webs
Progress in Oceanography, 1998Co-Authors: Joan Enric CartesAbstract:The distribution patterns of benthopelagic fauna and the macrofauna‐megafauna trophic relationships in the Benthic Boundary Layer (BBL) were studied. The study is based on data collected during 6 sampling cruises off the Catalan coast (western Mediterranean) during 1991‐1995 at depths ranging from 389‐1355 m. Crustaceans were the dominant benthopelagic macrofauna in the BBL level closest to the sea bed (~0‐1.5 m above bottom) on the Catalan Sea slope. Copepods and peracarid crustaceans (mysids, amphipods, isopods, and cumaceans) were dominant, whereas euphausiids and natantian decapods, some taxa of gelatinous plankton (siphonophores, medusae, and chaetognaths), and benthopelagic fishes were also well represented groups. Seasonal changes in megafaunal decapod crustaceans abundance seem to be linked to changes in the density and the biological cycle of BBL macrofauna, which constitute an important part of the available food exploited by megafauna. Both the advective and the vertical flow of organic matter in the north-western Mediterranean should simultaneously influence peaks of available food (BBL macrofauna) for bathyal‐megafaunal decapods. Recruitment of macrofaunal (suprabenthos and infauna) species at the level of canyons and neighbouring slope zones mainly occurred between late autumn‐late winter and would probably be mainly induced by an advective component. However, the macrofaunal sizes consumed by megafaunal decapods are found more abundantly represented in spring and summer populations. In parallel, the vertical fluxes seem to determine maxima in the abundance of planktonic organisms (especially copepods) which also occur in late spring‐summer. Size, natatory capability, and energetic value are important factors in the selection of food-resources by
Laurenz Thomsen - One of the best experts on this subject based on the ideXlab platform.
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processes in the Benthic Boundary Layer at the iberian continental margin and their implication for carbon mineralization
Progress in Oceanography, 2002Co-Authors: Laurenz Thomsen, T Vanweering, G GustAbstract:Abstract This paper evaluates the role of biological processes in the cycling of particulate organic matter within the Benthic Boundary Layer (BBL). It reveals that horizontal, advective fluxes of particulate matter exceed the vertically sinking fluxes through the water column. The data suggest that there is an important additional mechanism of carbon mineralization at hydrodynamically energetic continental margins, and that not the sediment surface but the near-bed fluid Layer of the BBL is the major region for organic carbon mineralisation, and the amount of carbon finally buried depends on the time that aggregates are exposed to the BBL. Water and sediment samples were taken during three cruises to the North East Atlantic continental margin. The study site covered the area between 41°N, 9°W and 44°N, 13°W with transects perpendicular to and along the continental margin, resolving velocity and particle features of the Benthic Boundary Layer [BBL] at 5–40 cm height above the sea floor. Particulate organic carbon in the BBL ranged from 29 to 102 mg m−3, total particulate matter from 1.2 to 6.2 g m−3 and Chloroplastic pigments from 0.01 to 0.26 mg m−3. Sediments on the continental margin consisted of an aggregated surface Layer, which covered the underlying sediments. At all stations, surface erosion yielded BBL aggregates > 100 μm at critical friction velocities [u∗c] of 0.4 to 1.2 cms−1. The erosion thresholds of underlying cohesive sediments typically increased from 1.1 to 1.8 cms−1 from shallow to deeper sites. Long-term flow velocity data reveal a tidally modulated flow field with repetitive cycling of particles between sea bed and suspension, representing altogether a situation of prolonged particle resuspension time, moderate residual currents and large variability of flow speed. The currents parallel and cross slope (north-south, on -and offslope) move the BBL aggregates with little net distance in one direction per tidal cycle. Within the ensuing particle transport loop alternating between bed and suspension mode, the material is redistributed. However, because of the low net downslope transport of these remoulded particles, little if any labile carbon reaches the steep lower continental slope via lateral advection within the study area.
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the Benthic Boundary Layer
2002Co-Authors: Laurenz ThomsenAbstract:Processes in the Benthic Boundary Layer (BBL) at different continental margins are described and the importance of lateral particle transport, particle aggregation, biological mediated particle deposition and resuspension within the BBL is discussed. Theoretical and methodical aspects of BBL research are demonstrated and examples of modern continental margin studies are given.
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factors controlling aggregate formation in the Benthic Boundary Layer of the mecklenburg bight western baltic sea
Journal of Sea Research, 1999Co-Authors: Sabine Jahmlich, Laurenz Thomsen, Gerhard GrafAbstract:Studies on aggregate formation and size distribution in relation to bottom water composition and flow regime were carried out in November 1994 at two transects in the inner and outer Mecklenburg Bight (Baltic Sea). The bottom water sampler ‘BIOPROBE’ (BWS) was used to collect 10-dm 3 water samples at 5, 10, 20 and 40 cm above the seabed. The outer transect samples tended to be more influenced by the open western Baltic Sea, whereas the inner transect samples were more affected by the coastal hydrography. Aggregate size distribution was investigated using a newly developed particle camera allowing identification of particles down to 150 mm size. Increasing concentrations of total particulate matter (TPM), particulate organic carbon (POC) and chlorophyll pigment equivalents (CPE) towards the seafloor together with a low proportion of POC=TPM (<5%) implied that the material was of resuspended origin. Aggregate size in both transects was positively correlated with TPM, transparent exopolymer particles (TEP) and bacterial cell abundance. Higher particle concentrations and aggregate numbers in the outer transect indicated a higher resuspension frequency, or lateral advection processes. The higher concentration of aggregates at the outer transect may reflect the larger amount of near-bottom transported material. © 1998 Elsevier Science B.V. All rights reserved.
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processes in the Benthic Boundary Layer at continental margins and their implication for the Benthic carbon cycle
Journal of Sea Research, 1999Co-Authors: Laurenz ThomsenAbstract:Abstract Processes in the Benthic Boundary Layer (BBL) at different continental margins are described and the importance of lateral advection, particle aggregation, biodeposition and the resuspension loops within the BBL are discussed. New methods of BBL research are demonstrated and a possible solution is given to the Benthic carbon budget problem (i.e. Benthic carbon demand versus vertical carbon flux) for continental margins in relation to the understanding of soft-bottom ecosystems.
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spatial and temporal variability of particulate matter in the Benthic Boundary Layer at the n w european continental margin goban spur
Progress in Oceanography, 1998Co-Authors: Laurenz Thomsen, Tj C E Van WeeringAbstract:Near bottom water samples and sediments were taken during five cruises to 6 stations forming a transect across the N.W. European Continental Margin at Goban Spur. Flow velocity spot measurements in the Benthic Boundary Layer (BBL) always increased from the shelf to the upper slope (1470 m) from 5 to 9 cm s−1 in spring/summer and from 15 to 37 cm s−1 in autumn/winter. Decreasing values were detected at the lower slope (2000 m) and the lowest values of ca. 2 cm s−1 at the continental rise at 4500 m water depth. Long term measurements with a Benthic lander at 1470 m show that currents have a tidal component and reach maximum velocities up to 20 cm s−1, sufficiently high periodically to resuspend and transport phytodetritus. During these long-term observations, currents were always weaker in spring/summer than in autumn/winter. Critical shear velocities of shelf/slope sediments increased with depth from 0.5 to 1.7 cm s−1 and major resuspension events and Intermediate Nepheloid Layers (INLs) should occur around 1000 m. Chloroplastic Pigment Equivalents (CPE) ranged from 0.0 to 0.21 μg dm−3, Particulate Organic Carbon (POC) from 12 to 141 μg dm−3 and Total Particulate Matter (TPM) from 0.2 to 10.0 mg dm−3. Aggregates in the BBL occurred with a median diameter of 152 to 468 μm. Data on suspended particulate matter in the near-bottom waters showed that hydrodynamic sorting within the particulate organic fraction occurred. Phytodetritus was packaged in relatively large aggregates and contributed little to the total organic carbon pool in nearbottom waters (CPE/POC ca.0.2%). The main organic fraction has low settling velocities and high residence times within the Benthic Boundary Layer. As POC was not concentrated in the near bed region the degree to which carbon is accessible to the Benthic community depends on aggregate formation, subsequent settling and/or biodeposition of the POC. Close to the sea bed downslope transport may dominate. Under flow conditions high enough to resuspend fresh phythodetritus from sediments at the productive shelf edge, this could be transported to 1500 m (Goban Spur) or abyssal depth (Canyon site between Meriadzek and Goban Spur) within 21 days.
K L Smith - One of the best experts on this subject based on the ideXlab platform.
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deep sea Benthic Boundary Layer communities and food supply a long term monitoring strategy
Deep-sea Research Part Ii-topical Studies in Oceanography, 2009Co-Authors: Alana D. Sherman, K L SmithAbstract:Long-term monitoring of deep-ocean processes is essential for understanding the potential impacts of climate variation on the deep sea. A suite of autonomous and cabled instrumentation has been developed to allow continuous measurements of food supply availability, species composition and abundance, and organism activity. A sedimentation sensor combines a traditional sediment trap configuration with a digital-imaging system and fluorometer to monitor food supply. A digital time-lapse camera system captures high-resolution images of the sea floor to monitor Benthic fauna and sediment processes. A bottom-transiting vehicle conducts photographic transects across the sea floor and measures sediment community oxygen consumption at multiple sites. An upward-looking acoustic array measures backscatter targets, pelagic fauna, passing through an insonified field above the sea floor. Although these instruments can be deployed autonomously, cabled observatories can now provide continuous power and real-time communications for sustained monitoring of deep-sea Benthic Boundary Layer communities.
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Benthic Boundary Layer communities and carbon cycling at abyssal depths in the central north pacific
Limnology and Oceanography, 1992Co-Authors: K L SmithAbstract:Cycling of carbon through the Benthic Boundary Layer (BBL) community in the deep sea is poorly understood. Until now, attempts to summarize the flow of organic C in these communities have relied primarily on data collected from various deep-sea areas. The one BBL community where the organic C pools and fluxes are best defined is in the central North Pacific, north of the Hawaiian Islands. This data base was combined with new estimates of standing stocks and organic C fluxes to construct an organic C budget for the bottom 600 m of the water column and the sediments, using net input from sinking particulate organic C (POC) and exchanges between 12 compartments. The largest standing stocks of C (dissolved organic C, suspended POC, and POC) were in the water and surface sediments (9.1 x lo8 g C km-2), exceeding that in the 10 consumer groups by almost four orders of magnitude. Of the consumer groups, the sediment nanobiota, meiofauna, and epiBenthic megafauna had the most organic C and the macrofauna had the least. Fluxes into the consumer groups, as estimated from respiration rates, were highest in the sediment community, bacterioplankton, and epiBenthic megafauna. The net flux of POC into the BBL (supply) ranged from -74 to + 1,268 g C km 2 d-l, which was generally insufficient to match the combined fluxes into the BBL consumer groups (demand) of 998-3,3 15 g C krnm2 d I. Other sources of organic C to fuel the demand of the BBL community are analyzed, including active transport by migrating abyssopelagic animals which might significantly augment the POC flux into the BBL at this oligotrophic midgyre station.
Ricardo M Letelier - One of the best experts on this subject based on the ideXlab platform.
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light induced growth of phytoplankton collected during the winter from the Benthic Boundary Layer off oregon usa
Marine Ecology Progress Series, 2004Co-Authors: Michael S Wetz, Patricia A Wheeler, Ricardo M LetelierAbstract:Despite the importance of the spring phytoplankton bloom off Oregon as a food source for zooplankton, little is known about the sources of phytoplankton seed stock for the bloom or its tim- ing. Experiments were conducted in the late winter to determine if the Benthic Boundary Layer (BBL) could be a source of viable phytoplankton and to determine to what extent their growth was limited by light. Water collected on 3 dates from the BBL over the inner-shelf and mid-shelf in January 2003 was used for growth experiments run in shipboard incubators held at 10°C. The water was exposed to in situ nutrient concentrations and to 4 light levels and 2 daylengths (9 and 12 h), representative of winter and spring daylengths. Significant increases in chl a and particulate organic matter (POM) were observed in high light and medium light treatments at both daylengths. Chl a increased mini- mally (≤0.3 µg l -1 ) in the low light treatments, while no significant increase in POM occurred. Chl a decreased in the control (no light) treatment throughout the experiments. Blooms that developed dur- ing these incubations were dominated by Thalassiosira spp., Actinopytchus sp., Asterionellopsis glacialis and other diatoms, consistent with in situ phytoplankton community composition during the spring. Growth occurred at light levels that were generally 40 to 50% of that measured in surface waters in January, suggesting that light levels at the surface are conducive to growth, but that mixing prevents significant growth during the winter.
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171 light induced growth of winter phytoplankton collected from the Benthic Boundary Layer in coastal oregon waters
Journal of Phycology, 2003Co-Authors: Michael S Wetz, Patricia A Wheeler, Ricardo M LetelierAbstract:It has been speculated that overwintering phytoplankton in the Benthic Boundary Layer (BBL) are seed stocks for spring blooms in coastal upwelling systems. Experiments were conducted in Jan/Feb 2003 to test the hypothesis that phytoplankton in the BBL are light limited. Water collected from the BBL at four sites across the northern Oregon shelf was incubated at in situ temperature and nutrient concentrations (∼1 μM phosphate, 10 μM nitrate, 15 μM silicate) and exposed to two different daylengths and four light levels. The daylengths were 9 h (winter) and 12 h (early spring), and the light levels (in μmol photons·m−1 ·s−1) were 0 (Control), 20 (L), 70 (M), and 160 (H). Light-induced growth was observed in all four incubations. Exponential growth was reached in the 12 H, 12 M, and 9 H treatments after 4 to 6 days, and stationary growth was reached after 5 to 10 days. Maximum in vivo fluoresence was obtained in the 12 H, 12 M, and 9 H treatments, while maximum particulate organic carbon (POC) was obtained in the 12 H treatment. In vivo fluorescence increased in the L light treatments relative to the control, but POC did not. Blooms were terminated by nitrate or silicate depletion. These results demonstrate that growth of winter phytoplankton off Oregon is primarily light-limited, and that input of light of sufficient intensity and constancy (i.e. water column stabilization) can lead to blooms on time scales typical of upwelling blooms (<1 week).
Alana D. Sherman - One of the best experts on this subject based on the ideXlab platform.
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Gelatinous zooplankton abundance and Benthic Boundary Layer currents in the abyssal Northeast Pacific: A 3-yr time series study
Deep Sea Research Part II: Topical Studies in Oceanography, 2020Co-Authors: Kenneth L. Smith, Christine L. Huffard, Paul R. Mcgill, Alana D. Sherman, Thomas P. Connolly, Susan Von Thun, Linda A. KuhnzAbstract:Abstract Gelatinous zooplankton are prominent fauna in the deep ocean, especially in the water column associated with the sea floor. This interface zone, the Benthic Boundary Layer, is critical to biogeochemical exchanges between pelagic and Benthic communities. A conspicuous member of this Benthic Boundary Layer community in the abyssal Northeast Pacific (Sta. M; 4000 m depth) is the hydrozoan medusa, Benthocodon pedunculata. A 3-year time-series study was conducted of B. pedunculata from October 2014 to November 2017 using an autonomous time-lapse camera system and acoustic current meter deployed on the sea floor. Remotely operated vehicle Benthic video transects and collections were also conducted during six servicing cruises for the long-term instruments. Over three years, a total of 123,887 B. pedunculata were recorded in hourly images with densities ranging from 0 to a high of 33 individuals m−3 in March 2016. Density of B. pedunculata was highest when current speeds were low, and declined precipitously as speed increased beyond ~1 cm s−1. Movement of B. pedunculata was parallel to the continental margin in northwest and southeast directions. The large numbers of B. pedunculata observed over this 3-year study suggests their ecological importance in the Benthic Boundary Layer food web at Sta. M.
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deep sea Benthic Boundary Layer communities and food supply a long term monitoring strategy
Deep-sea Research Part Ii-topical Studies in Oceanography, 2009Co-Authors: Alana D. Sherman, K L SmithAbstract:Long-term monitoring of deep-ocean processes is essential for understanding the potential impacts of climate variation on the deep sea. A suite of autonomous and cabled instrumentation has been developed to allow continuous measurements of food supply availability, species composition and abundance, and organism activity. A sedimentation sensor combines a traditional sediment trap configuration with a digital-imaging system and fluorometer to monitor food supply. A digital time-lapse camera system captures high-resolution images of the sea floor to monitor Benthic fauna and sediment processes. A bottom-transiting vehicle conducts photographic transects across the sea floor and measures sediment community oxygen consumption at multiple sites. An upward-looking acoustic array measures backscatter targets, pelagic fauna, passing through an insonified field above the sea floor. Although these instruments can be deployed autonomously, cabled observatories can now provide continuous power and real-time communications for sustained monitoring of deep-sea Benthic Boundary Layer communities.