Wednesday, June 6, 2007 - 9:15 AM
188

Where have all the mayflies gone? Patterns of impacts to Appalachian Ephemeroptera

Gregory J. Pond and Margaret E. Passmore. Environmental Assessment and Innovation Division, U.S. Environmental Protection Agency, 1060 Chapline St., Wheeling, WV 26003

Mayflies (Ephemeroptera) are common inhabitants of Appalachian streams often representing ~50% of the sampled individuals in benthic habitats. However in small streams in the Southwestern, Central, and Northern Appalachian ecoregions mayflies have nearly disappeared from many streams impacted by human disturbance. We analyzed state and federal datasets spanning 1999-2006 in portions of West Virginia and Kentucky to describe mayfly loss from basic chemical and physical stressors.  Compared to least-disturbed streams, both mayfly richness and abundance were more significantly reduced in streams affected by coal mining than residential impacts.  Mayflies were more negatively affected by increasing specific conductance or sulfate, than fecal coliform or RBP habitat score.  pH produced detrimental effects in both acid and alkaline conditions.  Facultative to tolerant mayflies of the study areas (e.g., Baetis, Plauditus, Caenis, Tricorythodes) were found in some of the impacted streams while many streams were completely devoid of mayflies.  Preliminary and experimental toxicity tests (6 d) using field-collected Epeorus (Heptageniidae) mayflies did not indicate short-term toxicity of synthetically-derived salt solutions or actual ambient mine discharge; however, disappearance of this taxon and other mayflies from streams is disturbing and calls for further research to address plausible mechanisms and future conservation efforts.

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