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Wenxiong Wang - One of the best experts on this subject based on the ideXlab platform.
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acute dietary pre exposure and trace metal bioavailability to the barnacle balanus amphitrite
Journal of Experimental Marine Biology and Ecology, 2004Co-Authors: P S Rainbow, Tania Y T Ng, Wenxiong WangAbstract:Rates of uptake from solution and Assimilation efficiencies of the trace metals Ag, Cd and Zn were investigated in the barnacle Balanus amphitrite after exposure in the laboratory for 19 days to low and high doses of added Ag and Cd in a diatom (Thalassiosira weissflogii) diet, the major route of metal uptake in barnacles. The hypothesis under test was that acute metal pre-exposure would affect the Assimilation Efficiency (AE) of that and other metals and their rate of uptake from solution. It was found that pre-exposure of the barnacles to atypically high dietary challenges of Cd and Ag did not cause changes in the rates of uptake of Cd, Ag or Zn from solution. Similarly, there was no clear consistent effect of dietary pre-exposure to Cd or Ag on the Assimilation Efficiency of Cd, Ag or Zn. The efflux rates of the metals were also comparable following the acute dietary exposure. Subcellular fractionation data indicated that the majority of the three metals were partitioned in the insoluble fraction, with very little in the soluble fraction consisting of metallothionein-like proteins and other (heat-sensitive) proteins. The lack of induction of increased Cd or Ag AE after pre-exposure in barnacles contrasts with results for mussels; this inconsistency is interpreted to result from differences in physiological accumulation patterns, the barnacles relying to an extreme extent on insoluble detoxification.
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Assimilation efficiencies of chemical contaminants in aquatic invertebrates a synthesis
Environmental Toxicology and Chemistry, 1999Co-Authors: Wenxiong Wang, Nicholas S. FisherAbstract:Assimilation efficiencies of contaminants from ingested food are critical for understanding chemical accumulation and trophic transfer in aquatic invertebrates. Assimilation Efficiency is a first-order physiological parameter that can be used to systematically compare the bioavailability of different contaminants from different foods. The various techniques used to measure contaminant Assimilation efficiencies are reviewed. Pulse-chase feeding techniques and the application of gamma-emitting radiotracers have been invaluable in measuring metal Assimilation efficiencies in aquatic animals. Uniform radiolabeling of food is required to measure Assimilation, but this can be difficult when sediments are the food source. Biological factors that influence contaminant Assimilation include food quantity and quality, partitioning of contaminants in the food particles, and digestive physiology of the animals. Other factors influencing Assimilation include the behavior of the chemical within the animal's gut and its associations with different geochemical fractions in food particles. Assimilation Efficiency is a critical parameter to determine (and to make predictions of) bioaccumulation of chemicals from dietary exposure. Robust estimates of Assimilation Efficiency coupled with estimates of aqueous uptake can be used to determine the relative importance of aqueous and dietary exposures. For bioaccumulation of metals from sediments, additional studies are required to test whether metals bound to the acid-volatile sulfide fraction of sediments can be available to benthic deposit-feeding invertebrates. Most Assimilation Efficiency studies have focused on chemical transfer in organisms at the bottom of the food chain; additional studies are required to examine chemical transfer at higher trophic levels.
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trace element trophic transfer in aquatic organisms a critique of the kinetic model approach
Science of The Total Environment, 1998Co-Authors: John R Reinfelder, Nicholas S. Fisher, Samuel N Luoma, John W Nichols, Wenxiong WangAbstract:The bioaccumulation of trace elements in aquatic organisms can be described with a kinetic model that includes linear expressions for uptake and elimination from dissolved and dietary sources. Within this model, trace element . trophic transfer is described by four parameters: the weight-specific ingestion rate IR ; the Assimilation Efficiency . . . AE ; the physiological loss rate constant k ; and the weight-specific growth rate g . These four parameters define e wx . the trace element trophic transfer potential TTPs IR ? AEr k q g which is equal to the ratio of the steady-state e trace element concentration in a consumer due to trophic accumulation to that in its prey. Recent work devoted to the quantification of AE and k for a variety of trace elements in aquatic invertebrates has provided the data needed e for comparative studies of trace element trophic transfer among different species and trophic levels and, in at least . one group of aquatic consumers marine bivalves , sensitivity analyses and field tests of kinetic bioaccumulation models. Analysis of the trophic transfer potentials of trace elements for which data are available in zooplankton, bivalves, and fish, suggests that slight variations in Assimilation Efficiency or elimination rate constant may determine . whether or not some trace elements Cd, Se, and Zn are biomagnified. A linear, single-compartment model may not be appropriate for fish which, unlike many aquatic invertebrates, have a large mass of tissue in which the concentrations of most trace elements are subject to feedback regulation. Q 1998 Elsevier Science B.V. All rights reserved.
Patricia Burkhardtholm - One of the best experts on this subject based on the ideXlab platform.
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biodegradable and petroleum based microplastics do not differ in their ingestion and excretion but in their biological effects in a freshwater invertebrate gammarus fossarum
International Journal of Environmental Research and Public Health, 2017Co-Authors: Sandrine Straub, Philipp E Hirsch, Patricia BurkhardtholmAbstract:Research on the uptake and effects of bioplastics by aquatic organisms is still in its infancy. Here, we aim to advance the field by comparing uptake and effects of microplastic particles (MPP) of a biodegradable bioMPP (polyhydroxybutyrate (PHB)) and petroleum-based MPP (polymethylmethacrylate (PMMA)) in the freshwater amphipod Gammarus fossarum. Ingestion of both MPP in different particle sizes (32-250 µm) occurred after 24 h, with highest ingestion of particles in the range 32-63 µm and almost complete egestion after 64 h. A four-week effect-experiment showed a significant decrease of the Assimilation Efficiency in amphipods exposed to the petroleum-based MPP from week two onwards. The petroleum-based PMMA affected Assimilation Efficiency significantly in contrast to the biodegradable PHB, but overall differences in direct comparison of MPP types were small. Both MPP types led to a significantly lower wet weight gain relative to the control treatments. After four weeks, differences between both MPP types and silica, used as a natural particle control, were detected. In summary, these results suggest that both MPP types provoke digestive constraints on the amphipods, which go beyond those of natural non-palatable particles. This highlights the need for more detailed research comparing environmental effects of biodegradable and petroleum-based MPP and testing those against naturally occurring particle loads.
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microplastics affect Assimilation Efficiency in the freshwater amphipod gammarus fossarum
Environmental Science and Pollution Research, 2016Co-Authors: Pascal Blarer, Patricia BurkhardtholmAbstract:An important issue in assessing microplastics is whether this newly emerging type of pollution affects freshwater invertebrates. This study was designed to examine the interactions between the amphipod Gammarus fossarum and two types of microplastics. To determine the ingestion and egestion of polyamide (PA) fibres (500 × 20 μm), amphipods were exposed to four concentrations (100, 540, 2680, 13,380 PA fibres cm−2 base area of glass beakers) and four exposure times (0.5, 2, 8, 32 h) as well as four post-exposure times (1, 2, 4, 16 h). We demonstrate a positive correlation between concentration and ingestion of PA fibres. Fibres were found in the gut after 0.5 h of exposure. Egestion was rapid and the digestive tract was empty 16 h after exposure ended. To investigate whether polystyrene (PS) beads (1.6 μm) can be taken up in the epithelial cells of the gut and the midgut glands, four concentrations (500, 2500, 12,500, 60,000 PS beads mL−1) were tested. Cryosections exhibited fluorescent PS beads only within the gut lumen. In a 28-day feeding experiment with both, fibres and beads, we studied the amphipod’s feeding rate, Assimilation Efficiency and wet weight change. The exposure to PA fibres (2680 PA fibres cm−2 base area of glass beakers) significantly reduced the Assimilation Efficiency of the animals. While both tested polymer types are ingested and egested, PA fibres can impair the health and ecological functions of freshwater amphipods under continuous exposure.
Nicholas S. Fisher - One of the best experts on this subject based on the ideXlab platform.
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Assimilation efficiencies of chemical contaminants in aquatic invertebrates a synthesis
Environmental Toxicology and Chemistry, 1999Co-Authors: Wenxiong Wang, Nicholas S. FisherAbstract:Assimilation efficiencies of contaminants from ingested food are critical for understanding chemical accumulation and trophic transfer in aquatic invertebrates. Assimilation Efficiency is a first-order physiological parameter that can be used to systematically compare the bioavailability of different contaminants from different foods. The various techniques used to measure contaminant Assimilation efficiencies are reviewed. Pulse-chase feeding techniques and the application of gamma-emitting radiotracers have been invaluable in measuring metal Assimilation efficiencies in aquatic animals. Uniform radiolabeling of food is required to measure Assimilation, but this can be difficult when sediments are the food source. Biological factors that influence contaminant Assimilation include food quantity and quality, partitioning of contaminants in the food particles, and digestive physiology of the animals. Other factors influencing Assimilation include the behavior of the chemical within the animal's gut and its associations with different geochemical fractions in food particles. Assimilation Efficiency is a critical parameter to determine (and to make predictions of) bioaccumulation of chemicals from dietary exposure. Robust estimates of Assimilation Efficiency coupled with estimates of aqueous uptake can be used to determine the relative importance of aqueous and dietary exposures. For bioaccumulation of metals from sediments, additional studies are required to test whether metals bound to the acid-volatile sulfide fraction of sediments can be available to benthic deposit-feeding invertebrates. Most Assimilation Efficiency studies have focused on chemical transfer in organisms at the bottom of the food chain; additional studies are required to examine chemical transfer at higher trophic levels.
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trace element trophic transfer in aquatic organisms a critique of the kinetic model approach
Science of The Total Environment, 1998Co-Authors: John R Reinfelder, Nicholas S. Fisher, Samuel N Luoma, John W Nichols, Wenxiong WangAbstract:The bioaccumulation of trace elements in aquatic organisms can be described with a kinetic model that includes linear expressions for uptake and elimination from dissolved and dietary sources. Within this model, trace element . trophic transfer is described by four parameters: the weight-specific ingestion rate IR ; the Assimilation Efficiency . . . AE ; the physiological loss rate constant k ; and the weight-specific growth rate g . These four parameters define e wx . the trace element trophic transfer potential TTPs IR ? AEr k q g which is equal to the ratio of the steady-state e trace element concentration in a consumer due to trophic accumulation to that in its prey. Recent work devoted to the quantification of AE and k for a variety of trace elements in aquatic invertebrates has provided the data needed e for comparative studies of trace element trophic transfer among different species and trophic levels and, in at least . one group of aquatic consumers marine bivalves , sensitivity analyses and field tests of kinetic bioaccumulation models. Analysis of the trophic transfer potentials of trace elements for which data are available in zooplankton, bivalves, and fish, suggests that slight variations in Assimilation Efficiency or elimination rate constant may determine . whether or not some trace elements Cd, Se, and Zn are biomagnified. A linear, single-compartment model may not be appropriate for fish which, unlike many aquatic invertebrates, have a large mass of tissue in which the concentrations of most trace elements are subject to feedback regulation. Q 1998 Elsevier Science B.V. All rights reserved.
Stephen M Secor - One of the best experts on this subject based on the ideXlab platform.
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effects of meal size clutch and metabolism on the energy efficiencies of juvenile burmese pythons python molurus
Comparative Biochemistry and Physiology A-molecular & Integrative Physiology, 2007Co-Authors: Christian L Cox, Stephen M SecorAbstract:We explored meal size and clutch (i.e., genetic) effects on the relative proportion of ingested energy that is absorbed by the gut (apparent digestive Efficiency), becomes available for metabolism and growth (apparent Assimilation Efficiency), and is used for growth (production Efficiency) for juvenile Burmese pythons (Python molurus). Sibling pythons were fed rodent meals equaling 15%, 25%, and 35% of their body mass and individuals from five different clutches were fed rodent meals equaling 25% of their body mass. For each of 11–12 consecutive feeding trials, python body mass was recorded and feces and urate of each snake was collected, dried, and weighed. Energy contents of meals (mice and rats), feces, urate, and pythons were determined using bomb calorimetry. For siblings fed three different meal sizes, growth rate increased with larger meals, but there was no significant variation among the meal sizes for any of the calculated energy efficiencies. Among the three meal sizes, apparent digestive Efficiency, apparent Assimilation Efficiency, and production Efficiency averaged 91.0%, 84.7%, and 40.7%, respectively. In contrast, each of these energy efficiencies varied significantly among the five different clutches. Among these clutches production Efficiency was negatively correlated with standard metabolic rate (SMR). Clutches containing individuals with low SMR were therefore able to allocate more of ingested energy into growth.
Marc Metian - One of the best experts on this subject based on the ideXlab platform.
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Overview of trace elements trophic transfer in fish through the concept of Assimilation Efficiency
Marine Ecology Progress Series, 2018Co-Authors: Simon Pouil, Paco Bustamante, Michel Warnau, Marc MetianAbstract:Fish bioaccumulate trace elements both from the surrounding water (across the gills) and through diet (via the gastrointestinal tract), with diet generally being the major contributor. A laboratory-based approach is currently the most appropriate way to precisely quantify the trophic transfer of trace elements in fish, and Assimilation Efficiency (AE) of trace elements from ingested food is a commonly determined parameter. However, there are still some discrepancies in the literature regarding the definition and the determination of AE in aquatic organisms and especially in fish. In this paper, we review the literature to provide a consolidated definition of the concept of AE as well as a description of the methods and protocols used to quantify the AE of trace elements. We also review the main studies of trace element AE in fish. Most studies reporting AE considered the effects of biotic factors, especially the influence of the quality of food, whereas abiotic factors have received less attention, although they affect fish physiology and, by extension, potentially affect the AE of trace elements. The need for further studies is thus noted, especially the influence of abiotic factors such as temperature, salinity or pH on trace element AE or in the context of the co-occurrence of multiple stressors; this will help us to better understand the trophic transfer of trace elements and thus their overall bioaccumulation in fish.
