Publication Date

5-2013

Advisor(s)

Barry Chernoff

Department

Biology

Language

English

Abstract

The goal of this work was to explore connections between foraging bats and stream ecosystems. While many studies have considered the influence of (mostly adult) prey and habitat, few have sought to integrate their direct, indirect and interacting effects. The first chapter seeks to identify influential prey and habitat variables and to produce models that explain the abundance of certain bat groups and associated benthic macroinvertebrates (BMI). The second chapter documents bat, BMI and fish communities before and after white-nose syndrome (WNS) became established in our state, and looks for evidence of a “release” response in the prey community of BMI, and the competitor community of fish. Numerous environmental variables were considered to help rule out potentially confounding effects of ecological variability. It has been suggested that because of the connection between bats and BMI, known to be sensitive to water quality and commonly used as indicators of stream health, that bats may also be bioindicators for rivers. The third chapter is a case-study testing this potential by comparing sites’ bat richness and abundance with BMI and fish water quality metrics. Over four years (2008-2012) at eight study sites along two Connecticut rivers, the Coginchaug and the East branch of the Eightmile, data was collected on bats, BMI and fish communities; adjacent terrestrial habitat; near and far landcover; and in-stream conditions of organic matter, substrate and water. Myotis, P. subflavus and E. fuscus were strongly associated with the abundance and/or habitat of two dominant groups of BMI, Diptera and Trichoptera (especially Hydropsychidae). Declines in WNS-vulnerable groups were consistent with others’ accounts, and data indicate an increase to groups with lower mortality, particularly E. fuscus. Evidence for predator and competitive release effects, i.e. increases to abundance of BMI and fish, was inconclusive, though arguably sufficient to warrant further investigation. There were little direct associations between measures of bat activity, such as richness and abundance, and BMI and fish metrics. Results indicate that low bat activity may be useful as an indication of poor stream conditions, while high bat activity may indicate greater nutrient inputs, productivity and biodiversity of the aquatic community.

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