Aquatic Vertebrate Assemblages in the Middle Trinity River Basin, with Emphasis on Turtles
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Rivers are dynamic ecosystems with considerable heterogeneity across multiple spatial scales. Environmental factors, such as depth, physical structure, flow regime and habitat connectivity influence species distributions across a floodplain, and subsequently there is a large body of work focused on understanding how these factors influence the structure of fish communities. There has also been increasing interest in understanding how environmental variation influences the community structure of another major aquatic vertebrate group, the turtles. I sampled fish and turtles at Gus Engeling Wildlife Management Area (WMA) and used ordination analyses to visualize environmental gradients that may influence community structure for these two vertebrate groups. Distributions of aquatic turtles and fishes at Gus Engeling WMA were associated with environmental gradients defined by flow regimes and substrate composition. When just turtles were considered, flow regimes were particularly important in describing habitat partitioning among species, particularly confamilial groups. A second study site, Keechi Creek WMA, was sampled for turtles in 2009. Keechi Creek WMA exhibited less habitat heterogeneity than Gus Engeling WMA, and as heterogeneity decreased between the two study sites, turtle species richness decreased, whereas habitat overlap between species increased. I analyzed the capture efficiency of 7 trap types used throughout the course of this project and found that effectiveness of each trap type varied by habitat type, species, and shell size. So, using a diversity of trap types increased my overall trapping success.
Riedle, Jimmy (2014). Aquatic Vertebrate Assemblages in the Middle Trinity River Basin, with Emphasis on Turtles. Doctoral dissertation, Texas A & M University. Available electronically from