Date of Award

Spring 2008

Document Type

Legacy Thesis

Degree Name

Master of Science in Coastal Marine and Wetland Studies

Department

Coastal and Marine Systems Science

College

College of Science

First Advisor

Eric T. Koepfler

Second Advisor

Christopher E. Hill

Third Advisor

Craig Gilman

Abstract

Loggerhead nest temperatures are subjected to a variety of external variables that influence nesting outcome. In this study loggerhead nest temperatures were recorded using data loggers that were placed into 86 nests at North Inlet, Cape Romain, and Edisto Beaches in South Carolina. Data loggers were deployed within four quarter periods between June and mid-August with most loggers allocated to the middle two quarters. The design allowed a spatial and temporal comparison of nest temperature, incubation duration, predicted sex ratio and hatching success. These nest variables were compared to climate and sediment characteristics. Multiple regressions of nest temperature against physical factors showed nest temperatures were most often dependent on total precipitation in the beginning of incubation and air temperature later in incubation within and between sites. At Edisto and Cape Romain, nest temperatures during the middle of the season were lightly higher and incubation time shorter than at the beginning and end of the season. The northern nesting beach (Pawleys Island and Debordieu) had a lower average nest temperature, estimated percentage of female hatchlings, and longer incubation periods than the southern beaches. Almost all nests were above the pivotal temperature and the majority procuded greater than 80% females. Roughly 30% of all nests produced clutches of entirely female hatchlings. Although 2007 was a drought year, the 1°C increase in temperature over the past 30 years at the sites may also have contributed to the 50% more females being produced in this study compared to the average sex ratio of 56.3 found between 1977 and 1982 by Mrosovsky (1984). Hatchery nests at Cape Romain were significantly cooler than in situ nests by an average of 0.4°C and incubation periods were shorter. Hatching success was not significantly different over time within beaches, between beaches, or between hatchery and in situ nests at Cape Romain.

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