title: Differential patterns of accumulation and retention of dietary trace elements associated with coal ash during larval development and metamorphosis of an amphibian.
abstract: We performed an experiment in which larval gray tree frogs (Hyla chrysoscelis) were raised through metamorphosis on diets increased with a suite of elements associated with coal combustion residues (silver [Ag], arsenic [As], cadmium [Cd], chromium [Cr], copper [Cu], mercury [Hg], lead [Pb], selenium [Se], vanadium [V], and zinc [Zn]) at "low" and "high" concentrations. We quantified accumulation of metals at three life stages (mid-larval development, initiation of metamorphosis, and completion of metamorphosis) as well as effects on survival, metabolic rate, size at metamorphosis, and duration and loss of weight during metamorphosis. Most elements were accumulated in a dose-dependent pattern by some or all life stages, although this was not the case for Hg. For most elements, larval body burdens exceeded those of later life stages in some or all treatments (control, low, or high). However for Se, As, and Hg, body burdens in control and low concentrations were increased in later compared with earlier life stages. A lack of dose-dependent accumulation of Hg suggests that the presence of high concentrations of other elements (possibly Se) either inhibited accumulation or increased depuration of Hg. The duration of metamorphosis (forelimb emergence through tail resorption) was lengthened in individuals exposed to the highest concentrations of elements, but there were no other statistically significant biological effects. This study shows that patterns of accumulation and possibly depuration of metals and trace elements are complex in animals possessing complex life cycles. Further study is required to determine specific interactions affecting these patterns, in particular which elements may be responsible for affecting accumulation or retention of Hg when organisms are exposed to complex mixtures of elements.
authors.affiliation: Chesapeake Biological Laboratory, University of Maryland Center for Environmental Science, Solomons, MD, 20688, USA, heyes@umces.edu.
authors.forename: Andrew
authors.initials: A
authors.lastname: Heyes
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Rowe
authors.forename: Phillip
authors.initials: P
authors.lastname: Conrad
mesh_terms: D000663:Amphibians; D000818:Animals; D060729:Coal Ash; D007814:Larva / Q000187:drug effects* / Q000254:growth & development; D008018:Life Cycle Stages / Q000187:drug effects; D008675:Metamorphosis, Biological / Q000187:drug effects*; D011898:Ranidae / Q000502:physiology*; D014131:Trace Elements / Q000378:metabolism* / Q000633:toxicity; D014874:Water Pollutants, Chemical / Q000378:metabolism* / Q000633:toxicity
chemical_list: D060729:Coal Ash; D014131:Trace Elements; D014874:Water Pollutants, Chemical