title: Strategies of Gammarus pulex L. to cope with arsenic--Results from speciation analyses by IC-ICP-MS and XAS micro-mapping.
abstract: The invertebrate shredder Gammarus pulex L. is a key species for aquatic carbon turnover via litter decomposition and can thrive in high-arsenic (As) environments. To understand their strategies for coping with increased As concentrations while fulfilling their ecosystem functions, we analyzed the As concentration and speciation in their aquatic habitat and in leaves with heterotrophic biofilms as their natural food source. We also followed the As distribution and speciation on the cuticle and within the body of G. pulex by X-ray absorption spectroscopic imaging. Half of the total As on G. pulex was found to be associated with the cuticle but was not taken up. Removing this externally bound As yielded only arsenate in the wash solution which reflects the speciation of the surrounding aquatic phase and shows that this As does not undergo any biotransformation. The major pathway into the organism is suggested to be incorporation via food intake, but only very low amounts of As were taken up or translocated from the gut system to other tissues. In one of the main food sources, leaves, 68% arsenate and 29% monomethylarsenate were found. After ingestion into the gut system, up to 23% of the more toxic arsenite was seen, but a substantial share was methylated to dimethylarsenate (46-56%). Little arsenate and arsenite were found in the adjacent tissues. Besides 76-80% mono- and di-methylarsenate, 10-21% of the As was complexed as As(III)-S species. G. pulex plays an important role in As cycling and our results indicate that As translocation from the gut to other tissues is minimized, but a transformation to other As-species occurred.
authors.affiliation: Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany. Electronic address: Joerg.Schaller@uni-bayreuth.de.
authors.forename: Jörg
authors.initials: J
authors.lastname: Schaller
authors.affiliation: Environmental Sciences Group, Royal Military College of Canada, 12 Verité Ave, P.O. Box 17000 Station Forces, Kingston, Ontario, Canada.
authors.forename: Iris
authors.initials: I
authors.lastname: Koch
authors.affiliation: Environmental Sciences Group, Royal Military College of Canada, 12 Verité Ave, P.O. Box 17000 Station Forces, Kingston, Ontario, Canada.
authors.forename: Guilhem
authors.initials: G
authors.lastname: Caumette
authors.affiliation: Environmental Sciences Group, Royal Military College of Canada, 12 Verité Ave, P.O. Box 17000 Station Forces, Kingston, Ontario, Canada.
authors.forename: Michelle
authors.initials: M
authors.lastname: Nearing
authors.affiliation: Environmental Sciences Group, Royal Military College of Canada, 12 Verité Ave, P.O. Box 17000 Station Forces, Kingston, Ontario, Canada.
authors.forename: Kenneth J
authors.initials: KJ
authors.lastname: Reimer
authors.affiliation: Environmental Geochemistry, Bayreuth Center for Ecology and Environmental Research (BayCEER), University Bayreuth, Universitätsstraße 30, 95447 Bayreuth, Germany.
authors.forename: Britta
authors.initials: B
authors.lastname: Planer-Friedrich
mesh_terms: D000222:Adaptation, Physiological; D033304:Amphipoda / Q000502:physiology*; D000818:Animals; D001151:Arsenic / Q000378:metabolism / Q000633:toxicity*; D002851:Chromatography, High Pressure Liquid; D014874:Water Pollutants, Chemical / Q000378:metabolism / Q000633:toxicity*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D014874:Water Pollutants, Chemical; D001151:Arsenic
keywords: Amphipods; Arsenic speciation; Invertebrates; Tissues; XANES