Aquatic Vertebrate Assemblages in the Middle Trinity River Basin, with Emphasis on Turtles
Abstract
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.
Citation
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 https : / /hdl .handle .net /1969 .1 /152827.