The influence of network structure, habitat fragmentation, and faunal sources on aquatic communities in headwater streams
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2017-04-07
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Towson University. Environmental Science and Studies Program
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Abstract
Headwater streams comprise the majority of the stream network, providing important ecological functions to the downstream network. Although we are beginning to understand how network structure may influence fish, our understanding of how it influences benthic macroinvertebrate dispersal and population connectivity is limited. We also know little about how these patterns and processes may be disrupted as a result of human-driven landscape change such as stream barriers to movement and creation of artificial habitats such as stormwater and farm ponds. In this study, I investigated the effect of stream network position, stream size, and local habitat on benthic macroinvertebrates, and determined to what degree road crossings and impoundments may be degrading benthic macroinvertebrate and fish communities in headwater streams. These mechanisms were explored using Maryland Department of Natural Resources, (MDNR) Maryland Biological Stream Survey (MBSS) benthic macroinvertebrate, fish, and environmental data from first-order streams in the Piedmont region of Maryland. Using an Information Theoretic Approach (ITA), models were developed based on the hypothesized relationships between benthic macroinvertebrate and fish community structure and several network and anthropogenic impact variables. Based on my results, aquatic community structure was dependent on local habitat conditions and stream network structure. Both assemblages responded negatively to roads, which may suggest an isolation effect. These results also suggest that impoundments are acting as sources for benthic macroinvertebrates and fish, including non-native species.