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Date of Award
Master of Science (MS)
Department of Biology
Prior to limitations placed on atmospheric emission of sulfur dioxide, Shenandoah National Park streams were heavily impacted by acid deposition. Acidification of these streams resulted in a depletion of acid neutralizing capacity (ANC) and a loss of fish species diversity. Differences in bedrock composition of park watersheds produce variation in stream response to acidification such that siliciclastic watersheds provide the lowest ANC, basaltic-carbonate watersheds provide the highest ANC, and granitic watersheds provide an intermediate ANC. Previous results by Bulger et al. (1995) indicated a significant relationship between ANC and fish species richness in thirteen park streams, such that low ANC streams in siliciclastic watersheds support less fish species diversity than relatively higher ANC streams in granitic and basaltic-carbonate watersheds. Given the potential for acidification recovery in the past two decades, has the relationship between fish species richness and ANC changed? The current study investigated changes in this relationship from 1995 to 2016 in the same thirteen park streams distributed among the three major bedrock regions of the park. Increases in fish species richness primarily occurred in well-buffered streams underlain with granitic and basaltic-carbonate bedrock while minimal increases in fish species richness were observed in siliciclastic watersheds. The strong correlation between fish species richness and ANC observed in 1995 still exists in 2016, indicating that park streams may still be experiencing legacy effects of past acidification.
Harmon, Patrick A., "Revealing the current relationship between stream acidification and fish species richness: What is the status after two decades of recovery?" (2017). Masters Theses. 499.