Identifier

etd-03302005-151536

Degree

Doctor of Philosophy (PhD)

Department

Renewable Natural Resources

Document Type

Dissertation

Abstract

Freshwater ecosystems, particularly streams and rivers, have been the subject of prodigious research. Unfortunately, in comparison to neighboring regions, the Gulf of Mexico coastal plain has not received as much attention. Therefore, I collected data on the macroinvertebrates of these streams to begin the understanding of the relationships between community structure and environmental characteristics. In contrast to the hypothesized ancestral streams of these macroinvertebrates, coastal plain streams are commonly devoid of rocks leaving only woody debris as usable hard substrates and are typically lower in dissolved oxygen. I examined habitat selection by colonization of woody debris with large and small surface areas. Secondly, given a similar surface area, I examined colonization in different levels of dissolved oxygen. Concurrently, I conducted biota and habitat surveys in three streams over four periods from August 2002 until April 2004 to collect baseline data for future investigations. The survey data included macroinvertebrate collections, microbial population estimations, water chemistry, and habitat descriptions. Finally, over the same time period, I collected macroinvertebrate, microbial, water chemistry, and habitat data in a stream with a potentially strong biotic disturbance, feral swine (Sus scrofa). All data were examined with appropriate multivariate statistics. The in-stream experiment suggested similar colonization of both sizes of woody debris for 20 of 21 taxa examined. Some potential high and low dissolved oxygen specialization was detected in the experiment, however, many macroinvertebrates (37%) appeared to be dissolved oxygen generalists. Further, survey data suggested more than 50% of collected macroinvertebrates also may be generalists with regard to other abiotic factors, but did demonstrate some affinity for woody debris. The single stream biotic disturbance appeared to significantly alter the macroinvertebrate community with a potential shift in favor of collecting organisms against scraping organisms. Therefore, in contrast with other regions, I suggest that coastal plain macroinvertebrates are tolerant to many abiotic factors, but are intolerant of some biotic disturbances.

Date

2005

Document Availability at the Time of Submission

Release the entire work immediately for access worldwide.

Committee Chair

William E. Kelso

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