Date of Graduation
Davis College of Agriculture, Natural Resources and Design
Wildlife and Fisheries Resources
Stuart A. Welsh.
The following thesis contains two chapters. In Chapter 1, I have reviewed and summarized literature pertaining to fishes and habitats of palustrine wetlands, the influence of hydroperiods on wetland fishes, the impacts of drought on wetland fishes, the importance of American alligators as ecological engineers of fish habitats within wetlands, and fish sampling within wetland habitats. Chapter 2 is a manuscript representing my thesis research. In this study, primary focus is placed on how fish diversity and how fish abundances of palustrine wetlands are influenced by drought conditions within the Blackjack Peninsula of the Aransas National Wildlife Refuge in southwestern Texas.;Seasonal hydroperiods and drought are natural disturbances that influence fish assemblages within subtropical palustrine wetlands. Few studies, however, have focused on the impacts of drought on fishes of freshwater wetlands, in part, because of the unpredictability and infrequent occurrences of drought conditions within wetland habitats. We analyzed the distribution, diversity, and abundances of fishes in relation to habitat characteristics during two wet/dry hydroperiod cycles within 77 palustrine wetland sites. During our study, below-average rainfall within two seasonal periods provided an opportunity to examine the effects of drought on the diversity and abundances of fishes and fish-habitat relationships. We captured 3,590 fishes representing 19 species and 10 families. The responses of fish diversity and total fish abundance to drought conditions were largely driven by six common species; western mosquitofish, warmouth, black bullhead, green sunfish, bluegill, and golden topminnow. Wetland volume, maximum water depth, salinity, and dissolved oxygen changed seasonally and across predrought, drought, and post-drought conditions, thereby influencing species diversity and species abundances. During the drought, fishes were restricted to reduced habitats which consisted primarily of deeper areas within constructed wetlands, and holes or dens of American alligators. Our data demonstrated that drought conditions greatly reduce species diversity and species abundance on the Blackjack Peninsula of southwestern Texas. Long-term studies, however, are needed to examine recovery of habitat and fish assemblage structure.
Welchert, Darrin M., "Relationships among fish assemblages, hydroperiods, drought, and American alligators within palustrine wetlands of the Blackjack Peninsula, Aransas National Wildlife Refuge, Texas" (2011). Graduate Theses, Dissertations, and Problem Reports. 3328.