Amphibians in natural systems must cope with a number of biotic and abiotic stressors that can potentially interact with pollutants to influence toxicity. Although interactive effects of short-lived pesticides with various environmental stressors have been studied, how persistent and bioaccumulative compounds such as metals interact with natural stressors to influence amphibians remains unexplored. We exposed the salamander Ambystoma talpoideum to coal-combustion wastes (a complex mixture of metals and metalloids, hereafter referred to as CCW) at low and high larval density throughout aquatic development in mesocosms simulating temporary wetlands. CCW and high density reduced survival to metamorphosis by 57-77% and 85-92%, respectively, and the effects of these two factors together were additive. Reduced metamorphosis was due in part to larval mortality prior to initiation of pond drying, but CCW and high density also extended the larval period, causing mortality of larvae that were not ready to metamorphose before the pond dried. To our knowledge, this is the first demonstration of a pollutant-induced extension of larval period leading to reduction in amphibian recruitment. Metamorphs were smaller in high density compared to low in reference ponds, but those from CCW emerged at similar sizes irrespective of density, suggesting less-than-additive effects of density and CCW on metamorph size. The adverse responses of salamanders to CCW were likely due to direct toxicity, as A. talpoideum metamorphs accumulated high concentrations of a suite of trace elements (As, Se, Sr, and V), and also to indirect effects on the community food web. We conclude that in no case did the addition of a natural stressor (high density) exacerbate CCW-related effects, but that the effects of CCW alone can be detrimental to larvae of salamanders that breed in temporary ponds.
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|Published - Aug 23 2006
Bibliographical noteFunding Information:
We would like to thank D. Scott, M.S. Tudor, R. Holem, J. Peterson, and K. Borgmann for their assistance with this project. This research as supported by the Environmental Remediation Sciences Division of the Office of Biological and Environmental Research, U.S. Department of Energy through the Financial Assistant Award #DE-FC09-96SR18546 to the University of Georgia Research Foundation. Manuscript preparation was funded by the University of Canberra's Vice Chancellor's Postgraduate Research Scholarship and the W.J. Weeden award to JHR.
- Ephemeral ponds
- Interactive effects
ASJC Scopus subject areas
- Aquatic Science
- Health, Toxicology and Mutagenesis