Wednesday, June 6, 2007 - 1:45 PM
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A Comparison of Microbial, Algal and Macroinvertebrate Communities in 4 Adirondack Mountain Streams Affected by Episodic Acidification

Randy Fuller, Matthew Neatrour, Jonathon Crossett, Devin Clifford, Maureen Lynch, Patrick McDermot, and Anne Samarco. Biology Department, Colgate University, Hamilton, NY 13346

We examined the effects of episodic acidification on leaf decomposition, periphyton biomass, and macroinvertebrate communities in four streams in the Adirondack Mountains.  From June to October 2005, ISCO samplers collected water samples continuously; scrapings from unglazed clay tiles were used to measure periphyton biomass, and macroinvertebrate density was determined using wire mesh cages that were filled with gravel.  Leaf breakdown rates, microbial respiration, and macroinvertebrate abundance were measured using leaf packs of individual and mixed species, of sugar maple (Acer saccharum) and American beech (Fagus grandifolia).  We found that increased rainfall was directly related to lower pH values.  However, periphyton ash free dry mass, chlorophyll a biomass, macroinvertebrate community richness, and abundance of macroinvertebrates did not correlate to stream pH levels.  Maple leaves had higher breakdown rates than beech leaves; during the summer, the stream with the highest pH had higher maple leaf breakdown rates, while shredder abundance was not affected by pH level.  Microbial activity was higher for maple leaves in the stream with the highest pH.  Our preliminary results suggest that episodic acidification events have less impact on macroinvertebrate and algal communities than the microbial communities that colonize decaying leaves.