Toxicity and climate change: Understanding their interactive effects and implications on population processes

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2013-08

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Abstract

The goal of this dissertation was to show how a more realistic exposure design can be employed to increase our understanding and predictive capabilities of adverse effects at the population level. We achieved a more realistic exposure design by incorporating exposures to both a contaminant and an emerging global change driver in climate change; specifically changing temperature. We further explored these exposure scenarios over the long term, since more often populations in the wild will experience not only multiple, concurrent stressors, but they will generally experience these stressors for many generations. Additionally, even if stressor intensity does subside, adverse effects may not go away or even lessen. In fact, adverse effects may not manifest until a much later life stage or even the next generation. Thus, the notion of exposure history emerges as an important consideration when determining responses to stressors. Natural systems are complex entities that are controlled and regulated by a multitude of physiochemical and biological processes, and also experience environmental stressors that vary both spatially and temporally. This dissertation shows that stressors that vary temporally can have profound impacts on population level endpoints. Climate predictions indicate an increase in extreme weather events and thus an increase in environmental instability. The high variability in environmental factors combined with the unpredictable nature of the effects complicates the interpretation of experiments based on short-term, single stressor exposures. This dissertation shows that short-term tests did not accurately predict effects of the multiple stressor exposure. Therefore, substantial effort should be made to increase realistic exposure scenerios by incorporating both multiple stressors and long-term, multigenerational exposures, while describing change in population level endpoints.

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Keywords

Climate change, Multiple stressors, Cadmium, Physa pomilia, Daphnia magna, Population effects

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