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Carl L Reiber - One of the best experts on this subject based on the ideXlab platform.
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influence of hypoxia on cardiac functions in the grass shrimp palaemonetes pugio holthuis
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 1999Co-Authors: Stacey L Harper, Carl L ReiberAbstract:Abstract Crustaceans frequently encounter hypoxic water and have evolved a variety of compensatory mechanisms to deal with low O2 conditions. Typically, large decapod crustaceans attempt to maintain cardiac output by increasing stroke volume to compensate for the hypoxia-induced bradycardia. Grass shrimp (Palaemonetes pugio), small hypoxic tolerant decapod crustaceans, were used to investigate cardiac responses to hypoxia in a smaller crustacean using videomicroscopy and dimensional analysis techniques. In addition, these techniques were compared to the more established dye dilution technique for calculation of cardiac output. No significant difference was found between the two methods for determining cardiac output in grass shrimp. Cardiac parameters (heart rate fH, stroke volume VS, and cardiac output Vb) were monitored in grass shrimp exposed to progressive hypoxia (PO2s=20, 13.3, 10, 5.3, and 2 KPa O2). Shrimp exhibit a cardiac response to hypoxia that is atypical when compared to larger crustaceans. Cardiac output was maintained until water PO2 fell below 10 KPa O2. This maintenance of Vb is consistent in both large and small decapods, however the mechanism differs. In grass shrimp, VS was PO2 dependent and declined significantly while fH increased significantly when PO2 was reduced to 13.3 KPa O2.
Joan Enric Cartes - One of the best experts on this subject based on the ideXlab platform.
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trophic relationships at intrannual spatial and temporal scales of macro and megafauna around a submarine canyon off the catalonian coast western mediterranean
Journal of Sea Research, 2010Co-Authors: Joan Enric Cartes, Emanuela Fanelli, Vanesa Papiol, Francesc MaynouAbstract:Abstract The spatial and temporal changes of near-bottom macrofauna (suprabenthos and macroplankton) and the trophic relationships of megabenthic decapod crustaceans were analyzed off the Catalonian coasts (western Mediterranean) around Berenguera submarine canyon in four periods (April and December 1991, March and July 1992) and four zones (within Berenguera Canyon at ca. 450 m, and on adjacent slope at ca. 400, 600 m and 1200 m). In March 1992, we found the highest macrofauna abundance and the smallest sizes in the canyon, suggesting a positive effect of river discharges on suprabenthos recruitment. By contrast, macroplankton (decapods, fishes and euphausiids) did not show higher recruitment into canyons. After analyzing the diet of 23 decapod crustaceans, we found a significant segregation between guilds feeding on zooplankton and on benthos. Zooplankton (euphausiids and Pasiphaeidae) and infauna (polychaetes, Calocaris macandreae and ophiuoroids) were consistently the main prey exploited by decapod crustaceans around Berenguera Canyon. We also found some macrophyte ( Posidonia oceanica ) consumption, which was higher in periods of water column homogeneity (winter–spring and late autumn). Positive correlations between decapods' gut fullness ( F ) and decapod abundance indicate feeding aggregations, while positive correlations were also found between F and Llobregat River (situated ca. 18 km from Berenguera head) flow 1 to 2 months before sampling. Increases in F were delayed only 1 month when zooplankton feeders were analyzed alone, while benthos feeders did not show significant relationships with any environmental variables. That indicates that the response of megabenthic decapods feeding on benthos to environmental shifts is slower than that of zooplankton feeders. The importance of river flows in enhancing food supply of macro- and megabenthos dwelling close to submarine canyons was apparent, with a delay in the fauna response of 0–2 months after river flow peaks.
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community structure and dynamics of deep water decapod assemblages from le danois bank cantabrian sea ne atlantic influence of environmental variables and food availability
Progress in Oceanography, 2007Co-Authors: Joan Enric Cartes, Alberto Serrano, Francisco Velasco, Santiago Parra, Francisco Arreguin SanchezAbstract:Abstract The community structure of the decapod crustaceans inhabiting Le Danois Bank (Cantabrian Sea, NE Atlantic Ocean) was studied on two cruises performed in October 2003 and April 2004. Otter and beam-trawls were used to collect this fauna. At depths ranging between 455 and 1048 m, we found distinct decapod assemblages on the bank summit and deeper in the inner basin (between the bank and the continental shelf). The faunal discontinuity between these groups appeared at around 600 m (e.g. between 612 and 642 m in the basis of species replacement). The summit assemblage was characterized by low diversity (in terms of number and relative abundances of species) and by the dominance of hermit crabs (Pagurus alatus, Anapagurus laevis, Pagurus excavatus), the crangonid Pontophilus spinosus and the squat lobster Munida sarsi. Species characterizing the deeper assemblage, which was richer in terms of diversity, were Munida tenuimana, Parapagurus pilosimanus, Pontophilus norvegicus, the crab Geryon trispinosus and a number of bathypelagic shrimps (Sergia robusta, Acanthephyra pelagica and Pasiphaea tarda). Changes in decapod composition characterized by multidimensional scaling analyses were correlated with different variables, e.g. %mud and %organic matter (OM), temperature and salinity close to the bottom. Among those the %OM and %mud in sediments affected decapod distributions the most. The summit of the bank was covered by fine sediments with low proportion of mud (13.9–29.3%) and OM (2.55–3.50%). By contrast, sediment of the inner basin had a higher proportion of OM and mud (64.1–84.2%; 6.26–7.00%, respectively). The low proportion of mud at the summit of Le Danois Bank may explain the absence or scarcity of burrowing species (e.g. the lobster Nephrops norvegicus, the shrimps Calocaris macandreae and Alpheus glaber and the crab Goneplax rhomboides), that are dominant at similar depths (400–500 m) in the upper muddy assemblage on the mainland-continental slope in the Bay of Biscay (44–46°N). The dominance of certain species on the summit of submarine mounts can probably be related to their biology and feeding ecology. For example, pagurids are deposit feeders, even consuming marine snow (e.g. Chl-a identified in guts of Pagurus alatus), and they have low gut fullness (probably indicating a capacity to withstand long periods under starvation), that would favour their adaptability to a rather unpredictable habitat such as Le Danois Bank summit. Regarding prey availability, zooplankton/micronekton and infauna distributed around Le Danois Bank showed different depth-related patterns. Among zooplankton, mesopelagic decapods, mysids, and fishes were absent at the bank summit, while euphausiids exhibited high abundances over the summit. No significant trends with depth were found for infauna abundance, and for instance polychaete densities were similar both at the summit and the inner basin. Therefore, prey availability was lower for summit assemblages regarding zooplankton/micronekton. Patterns in mean size vs. depth were species specific for decapods, and the possible role of the bank summit as a recruitment area was not general for the whole decapod assemblage.
Stacey L Harper - One of the best experts on this subject based on the ideXlab platform.
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influence of hypoxia on cardiac functions in the grass shrimp palaemonetes pugio holthuis
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 1999Co-Authors: Stacey L Harper, Carl L ReiberAbstract:Abstract Crustaceans frequently encounter hypoxic water and have evolved a variety of compensatory mechanisms to deal with low O2 conditions. Typically, large decapod crustaceans attempt to maintain cardiac output by increasing stroke volume to compensate for the hypoxia-induced bradycardia. Grass shrimp (Palaemonetes pugio), small hypoxic tolerant decapod crustaceans, were used to investigate cardiac responses to hypoxia in a smaller crustacean using videomicroscopy and dimensional analysis techniques. In addition, these techniques were compared to the more established dye dilution technique for calculation of cardiac output. No significant difference was found between the two methods for determining cardiac output in grass shrimp. Cardiac parameters (heart rate fH, stroke volume VS, and cardiac output Vb) were monitored in grass shrimp exposed to progressive hypoxia (PO2s=20, 13.3, 10, 5.3, and 2 KPa O2). Shrimp exhibit a cardiac response to hypoxia that is atypical when compared to larger crustaceans. Cardiac output was maintained until water PO2 fell below 10 KPa O2. This maintenance of Vb is consistent in both large and small decapods, however the mechanism differs. In grass shrimp, VS was PO2 dependent and declined significantly while fH increased significantly when PO2 was reduced to 13.3 KPa O2.
Kenneth W Able - One of the best experts on this subject based on the ideXlab platform.
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diel variation in decapod crustacean and fish assemblages in new jersey polyhaline marsh creeks
Estuarine Coastal and Shelf Science, 1993Co-Authors: Rodney A Rountree, Kenneth W AbleAbstract:Diel variation in fish and decapod crustacean abundance and species assemblages were examined in two studies to determine patterns of subtidal and intertidal marsh creek habitat use in a southern New Jersey estuary. In the first study, two subtidal marsh creeks were sampled with weirs from April-November 1988 (n = 42) and seines from July-November 1988 (n = 33), while in the second study two intertidal creeks were sampled with weirs from July-October 1989 (n = 28). Fish and decapod species assemblages captured in subtidal weir, subtidal seine and intertidal weir, as measured by both relative abundance and canonical discrimination analyses, were all highly affected by diel period. Total abundance and abundances of 15 species of fish and decapods exhibited significant diel differences, some of which were strongly influenced by season and life history stage (i.e. size cohorts). A detailed examination of the most abundant species, Menidia menidia, reveals that adults were more abundant during the day in early summer, suggesting diurnal reproductive movements into the creeks. In contrast, young-of-the-year cohorts were significantly more abundant at night during the late summer and fall, suggesting nocturnal movement into shallow marsh creek habitats. Our observations of strong diel differences in species assemblages point out the need for both day and night sampling in marsh habitats, if the importance of these habitats to fishes and decapods are to be fully understood.
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a comparison of eelgrass sea lettuce macroalgae and marsh creeks as habitats for epibenthic fishes and decapods
Estuarine Coastal and Shelf Science, 1991Co-Authors: Susan M Sogard, Kenneth W AbleAbstract:Densities of epibenthic fishes and decapod crustaceans (excluding xanthids and pagurids) were quantified with daytime throw trap sampling in shallow water habitats of New Jersey estuaries. We compared eelgrass (Zostera marina), sea lettuce macroalgae (Ulva lactuca), unvegetated sand/mud substrates adjacent to these vegetation types, and saltmarsh creeks. The highest total density of fishes occurred in marsh creeks, due primarily to high abundances of Menidia menidia. The highest total decapod density was also in a marsh creek, but only slightly surpassed the density in Zostera. Results of apriori comparisons tests for individual species demonstrated that vegetation (either Zostera or Ulva) was superior in quality (based on fish and decapod densities) to adjacent unvegetated substrates. Sites with Zostera as the dominant vegetation had higher densities of most fish species than sites with Ulva as the dominant vegetation, but only one decapod, Hippolyte pleuracanthus, was more abundant at eelgrass sites. Ulva lactuca, therefore, was an important habitat in areas lacking Zostera marina; for the decapods the two vegetation types were comparable in habitat quality, but for fishes Ulva did not provide an equivalent substitute for Zostera. Marsh creeks supported very high densities, but only for a few species that were also common in other habitats. Comparison of recruitment patterns suggested many species do not begin exploiting these estuarine habitats until relatively late in the summer, perhaps as result of peak spawning in mid-summer.
Francesc Maynou - One of the best experts on this subject based on the ideXlab platform.
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trophic relationships at intrannual spatial and temporal scales of macro and megafauna around a submarine canyon off the catalonian coast western mediterranean
Journal of Sea Research, 2010Co-Authors: Joan Enric Cartes, Emanuela Fanelli, Vanesa Papiol, Francesc MaynouAbstract:Abstract The spatial and temporal changes of near-bottom macrofauna (suprabenthos and macroplankton) and the trophic relationships of megabenthic decapod crustaceans were analyzed off the Catalonian coasts (western Mediterranean) around Berenguera submarine canyon in four periods (April and December 1991, March and July 1992) and four zones (within Berenguera Canyon at ca. 450 m, and on adjacent slope at ca. 400, 600 m and 1200 m). In March 1992, we found the highest macrofauna abundance and the smallest sizes in the canyon, suggesting a positive effect of river discharges on suprabenthos recruitment. By contrast, macroplankton (decapods, fishes and euphausiids) did not show higher recruitment into canyons. After analyzing the diet of 23 decapod crustaceans, we found a significant segregation between guilds feeding on zooplankton and on benthos. Zooplankton (euphausiids and Pasiphaeidae) and infauna (polychaetes, Calocaris macandreae and ophiuoroids) were consistently the main prey exploited by decapod crustaceans around Berenguera Canyon. We also found some macrophyte ( Posidonia oceanica ) consumption, which was higher in periods of water column homogeneity (winter–spring and late autumn). Positive correlations between decapods' gut fullness ( F ) and decapod abundance indicate feeding aggregations, while positive correlations were also found between F and Llobregat River (situated ca. 18 km from Berenguera head) flow 1 to 2 months before sampling. Increases in F were delayed only 1 month when zooplankton feeders were analyzed alone, while benthos feeders did not show significant relationships with any environmental variables. That indicates that the response of megabenthic decapods feeding on benthos to environmental shifts is slower than that of zooplankton feeders. The importance of river flows in enhancing food supply of macro- and megabenthos dwelling close to submarine canyons was apparent, with a delay in the fauna response of 0–2 months after river flow peaks.
