Surveys of basking map turtles Graptemys spp. in three river drainages and the importance of deadwood abundance

Graptemys gibbonsi Lovich and McCoy 1992 – Pascagoula Map Turtle, Pearl River Map Turtle, Gibbons’ Map Turtle

“…Of all the sites surveyed, G. gibbonsi never outnumbered G. oculifera within the Pearl River system and only outnumbered G. flavimaculata within the Chickasawhay River (1.5:1), Chunky River (no G. flavimaculata seen), and Black Creek (2:1), all of which are within the Pascagoula River system. Graptemys gibbonsi densities were also positively correlated with emergent deadwood abundance (Lindeman 1999). Lower G. gibbonsi levels in these drainages in comparison to prior surveys by Cagle and others were attributed to declining water quality and the negative impacts it has on mollusk populations, the primary food item of G. gibbonsi.…”

“…Cagle (1953) . mutica, S. carinatus, A. spinifera, G. flavimaculata, T. scripta, P. concinna, M. temminckii, and S. odoratus. During the 1990s, Lindeman (1998Lindeman ( , 1999 conducted spotting scope surveys throughout the Pearl and Pascagoula River systems. Graptemys gibbonsi were found to occur at much lower densities throughout the Pearl and Pascagoula River systems in comparison to G. oculifera and G. flavimaculata, both of which are federally listed species.…”

“…Such was not always the case. Lindeman (1999) analyzed historical population trends that show G. gibbonsi was almost twice as abundant as G. oculifera on the Pearl River in the 1950s and 1960s, but less common than G. oculifera in the late 1970s. By the late 1980s and early 1990s, the ratio of G. oculifera to G. gibbonsi ranged from 1.9:1 to 125:1.…”

Graptemys pulchra Baur 1893 – Alabama Map Turtle

“…The response of G. pulchra to these habitat alterations is unknown. Stream channelization, particularly in the Tombigbee River, and removal of snags, has destroyed habitat in other areas (Lindeman 1999). Impoundment of rivers affects the food base of riverine turtles, especially dietary specialists (Tucker et al 2012), and probably produces habitat unsuitable for those species, although individuals may survive in lakes.…”

Graptemys oculifera (Baur 1890) – Ringed Map Turtle, Ringed Sawback

“…8a). Most descriptions of the habitat of this species (McCoy and Vogt 1980;McCoy and Vogt 1988;Dundee and Rossman 1989;Dickerson and Reine 1996;Lindeman 1999;Buhlmann et al 2008) have noted fast to moderate currents, the presence of numerous basking logs, the presence of sandbars used for nesting, and a channel wide enough to allow sunlight to penetrate to the surface for much of the day.…”