Abstract

Headwater streams are known to have an impact on higher order river systems downstream; therefore, it is important to monitor their water quality. The United States Army is mandated to ensure their training activities do not have a negative impact on freshwater biotic communities and the overall water chemistry. The goals of this study include: (1) to quantify the long-term effects of military land management practices on headwater stream biodiversity in western Louisiana using biological indices and (2) to measure changes in fish and macroinvertebrate assemblages over time using multivariate techniques. Because the natural disturbance regime in these streams is more ‘harsh,’ it was expected that anthropogenic disturbances would have less of an impact on the fish and macroinvertebrate assemblages. Also, because insects at different life history stages can choose breeding sites based on environmental conditions at a stream locality and have the potential to cross drainage basin boundaries, it was anticipated that macroinvertebrate assemblages would not vary statistically between drainages. In contrast, most fish species are constrained to their historically defined drainage basins; therefore, it was predicted that environmental factors relating to both year and drainage would affect fish assemblage composition. From 2001 to 2016, 19 streams from the Calcasieu, Red, and Sabine River drainages were sampled to determine the structure of fish and macroinvertebrate assemblages. Over 15,000 macroinvertebrates and 3,000 fish were collected and analyzed. As predicted, macroinvertebrate water quality scores did not differ across drainage basins, and multivariate analysis confirmed this pattern. In contrast, fish water quality scores did differ across drainage basins; again, this pattern was confirmed by multivariate analysis, also supporting the original hypothesis. Overall, when the trends across years are examined, community structure of fish and macroinvertebrates in these streams are quite stable. These long-term datasets are important from a conservation perspective to understand how humans are impacting aquatic ecosystems.

Date of publication

Spring 6-5-2017

Document Type

Thesis

Language

english

Persistent identifier

http://hdl.handle.net/10950/578

Committee members

Lance Williams, Marsha Williams, Kate Hertweck, Josh Banta

Degree

Master of Science in Biology

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