A Comparison of Three Sampling Gears for Capturing Aquatic Turtles in Missouri: The Environmental Variables Related to Species Richness and Diversity

Donaldson Point Conservation Area (DPCA) is a lentic area within the Mississippi River floodplain that experiences seasonal flooding because of direct connectivity to the Mississippi River. Sampling for aquatic turtles was conducted during fall (October–November 2003) and spring (April–May 2004) using fyke nets, hoop nets and basking traps in both round and linear pools. Hoop nets were deployed with and without the use of leads, whereas paired fyke nets were positioned with their leads tied together or straight from the bank. The performance of each net and the turtle species captured were assessed. Catch-per-unit effort (CPUE) when using hoop nets and fyke nets was considerably greater in fall than in spring. Fyke nets set perpendicular to the bank produced a CPUE greater than did the other gears deployed in the spring and fall. We captured eight turtle species: Trachemys scripta elegans, Graptemys pseudogeographica pseudogeographica, Alapone muticus muticus, Alapone spinifer spinifer, Sternotherus odoratus, Graptemys ouachitensis, Chrysemys picta dorsalis and Chelydra serpentina serpentina. Species richness was greater in areas with deeper water with low transparency, and lower in water with high dissolved oxygen and with greater depth of hoop net deployment. Species abundance was the lowest when hoop nets were deployed in linear water bodies with high turbidity, lower pH and low dissolved oxygen. Because turtle species are important biotic components of large river communities, protecting floodplain aquatic habitats such as those found within DPCA may help sustain large river turtle assemblages.