Thursday, May 29, 2008 - 10:15 AM
521

(TALK WITHDRAWN BY AUTHOR) modeled effects of climate change on biodiversity and food-web dynamics in rocky mountain streams

Marjorie L. Brooks, Zoology and Physiology, University of Wyoming, 1000 E. University Ave. Dept 3166, Laramie, WY 82071, Robert E. Zuellig, Colorado Water Science Center, U.S. Geological Survey, Denver, CO 80225, William H. Clements, Department of Fish, Wildlife, & Conservation Biology, Colorado State University, Fort Collins, CO 80523, and Donna R. Kashian, Great Lakes Environmental Research Laboratory, Ann Arbor, MI 48105.

Snow pack levels across the Rocky Mountains are expected to decrease by 50 to 100% by 2050 causing lower in-stream flow and earlier seasonal exposure of streams to UV radiation.  Metal bioavailability is greatly decreased by its complexation with dissolved organic carbon (DOC).  Because UV destroys DOC and alters the composition of remaining DOC, increased UV can greatly increase metals availability.  Based on field studies that quantified the effects of metals on macroinvertebrate stream communities, we developed a dynamical model of how increased UV exposure due to shorter seasonal duration of snow cover, slowed stream flow, and lower water levels might be predicted to shape the future structure of stream communities.  According to the model, the most heavily impacted sites were those in which high concentrations of dissolved organic carbon played an important role in binding metals and mitigating toxicity.  Aside from UV effects, the model demonstrates how differential susceptibility of species to metals removes competitive dominants, which allows population increases in grazers and promoted greater species richness among predators.  Model results suggest how climate change will structure species diversity and trophic interactions in high-altitude streams.


Web Page: Climate change, ecotoxicology, biodiversity

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