Spatial and temporal use of floodplain habitats by lentic and lotic species of aquatic turtles

Abstract

We investigated the use of aquatic and terrestrial floodplain habitats by lentic and lotic turtles inhabiting the Missouri River, a contemporary, regulated large river. Specifically, we tested whether habitats were used differentially by turtle species, sexes, and life stages over biologically determined spatial and temporal scales. We monitored female and male false map turtles (Graptemys pseudogeographica) and slider turtles (Trachemys scripta) for 14 months, using radiotelemetry. In addition, over a 3-year period we trapped G. pseudogeographica (n=591) and T. scripta (n=129) to supplement data on habitat use. Movements based on radiotelemetry and recaptures were summarized for each individual. Both species of turtles displayed dynamic annual activity patterns and used diverse habitats including those typically considered terrestrial. Although G. pseudogeographica and T. scripta spent a substantial portion of the year in the Missouri River (primarily in the cool months), newly created scour habitats also appeared to attract turtles during the cool season. However, in the warm months, habitat use became much more diverse, with turtles occupying all identified habitats including flooded agriculture and forest. Relative to their proportions, slough and scour habitats appeared to be highly favored while forests older than 4 years and agricultural habitats were proportionally less favored. We found few differences between species. However, males of both species were consistently more sedentary, used half as many habitats, and moved half as far from the river as did females, especially during May through July. Juveniles of both species were captured on average farther from the river than were adults, perhaps reflecting the close proximity of both nesting areas and shallow, productive habitats free of aquatic predators. We estimate a riparian zone of 449 m that encompasses 95% of the population movements away from the river and discuss the quality of habitats important to reproduction and survival of lentic and lotic floodplain turtles. These spatial and temporal movement patterns, in light of their potential adaptive costs and benefits to G. pseudogeographica and T. scripta, are critical to understanding the ecology of long-lived vertebrates that depend on contemporary large rivers.

Do geographically isolated wetlands influence landscape functions?

“…Indeed, models predict that loss of GIW habitats would impact a wide array of fauna, not just permanent residents, and most prominently, turtles, amphibians, birds, and small mammals (36), many of which are imperiled (38). That many organisms use both GIWs and downstream waters [turtles (129), birds (130,131), snakes (132), and alligators (30)], in different seasons (121) or life stages (30,133), illustrates that the entire connectivity continuum, including GIWs, impacts habitat heterogeneity and redundancy, regional biodiversity, and, thus, the biological integrity of downstream waters.…”

A simple field method for assessing the ecological quality of riparian habitat in rivers and streams: QBR index

“…It can support a high biodiversity, especially in large floodplain rivers (Naiman and D! e ecamps, 1997), protect the main channel from temporal changes and buffer large disturbances (Whiting and Pomeranets, 1997) and provide refuge and food for wildlife (Naiman et al, 1993;Stanford and Ward, 1993;Bodie and Semlitsch, 2000). The structure and function of this riparian habitat can either be extremely complex and heterogeneous, as in floodplain rivers, or relatively simple such as alongside headwater streams.…”

Forelimb kinematics and motor patterns of the slider turtle (Trachemys scripta) during swimming and walking: shared and novel strategies for meeting locomotor demands of water and land

“…Like many freshwater turtles, sliders spend considerable time in the water, but also move over land to perform vital tasks such as nesting, basking or moving between aquatic habitats (Gibbons, 1970;Gibbons, 1990;Ernst et al, 1994;Bodie and Semlitsch, 2000). Sliders must use the same set of muscles to produce these movements under the different performance demands of both habitats.…”