All ETDs from UAB

Advisory Committee Chair

Thane Wibbels

Advisory Committee Members

Ken Marion

David Nelson

Document Type

Thesis

Date of Award

2012

Degree Name by School

Master of Science (MS) College of Arts and Sciences

Abstract

The diamondback terrapin (Malaclemys terrapin) was once an abundant and economically important species in the salt marshes of Alabama. A variety of threats have impacted this species over the past century, resulting in a drastic decline in the population. Diamondback terrapins are currently considered a "priority one species (highest conservation concern)" in Alabama. The largest nesting aggregation documented to date in Alabama is on the 1.8 km long shell-hash nesting beach bordering the western edge of Cedar Point Marsh (CPM). The current studies address several aspects of the reproductive ecology of the diamondback terrapin in Alabama. Nesting beach surveys were conducted over four nesting seasons to monitor depredated nest abundances and locations on CPM nesting beach from 2008-2011. The mean number of depredated nests recorded each year was 131± 24. Nesting did not show uniform distribution over the length of the nesting beach, with factors such as vegetation and distance from the salt marsh channels possibly playing a role. Mark-recapture data for nesting females from 2011, as well as previously reported data (2006-2010) indicate that approximately 53 adult females utilize the CPM nesting beach. Eighteen adult females were tagged with radio transmitters over the 2010 and 2011 nesting seasons. Radio telemetry data indicate the CPM nesting beach is utilized by not only adult females that remain resident in CPM, but also adult females resident in adjacent marshes in the Heron Bay area. This highlights the importance of CPM and the Heron Bay area as critical habitat for terrapins in Alabama. Female-biased hatchling sex ratios were predicted in the 2011 nesting for the CPM nesting beach; only nests laid early in the nesting produce mixed sex ratios. Surrogate nest studies also showed a female-biased sex ratio, indicating the temperature-based model is a good predictor of sex on this beach. Radioimmunoassay was used to examine the serum testosterone levels of juvenile terrapins as a potential sexing technique. Results indicate that serum testosterone levels are a practical method for sexing juvenile terrapins. The results of this thesis provide critical information for enhancing the management strategy and recovery of the diamondback terrapin in Alabama.

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