Climatic and oceanographic factors affecting daily patterns of juvenile sea turtle cold-stunning in Cape Cod Bay, Massachusetts

Publication Date

2005

Journal or Book Title

Chelonian Conservation And Biology

Abstract

We examined the climatic factors that may affect the temporal patterns of juvenile sea turtle cold-stunning and whether local extent and temporal scale oceanographic and climatic factors that induce cold-stunning are different for different species. Using classification tree models, we demonstrate that juvenile Kemp's ridley (Lepidochelys kempii) and loggerhead (Caretta caretta) sea turtles cold-stun under slightly differing oceanographic and climatic conditions within any given year. In Cape Cod Bay, Massachusetts, cold-stunned juvenile Kemp's ridley sea turtles are recovered with greater frequency (55%) during November, while the vast majority of juvenile cold-stunned loggerhead sea turtles (79%) are recovered in December. Our classification tree models suggest cold-stunned juvenile Kemp's ridleys are more often recovered from 9 November to 9 December on days with sea surface temperatures between 7.0 and 10.4 degrees C, wind speeds exceeding 5.3 m/s, air temperatures below 10.4 degrees C, and barometric pressures exceeding 1009.5 mm. Our models also suggest cold-stunned juvenile loggerheads are recovered after 5 December on days with sea surface temperatures between 5.6 and 9.0 degrees C, wind speeds exceeding 7.6 m/s, and barometric pressure exceeding 1015.9 mm. Mean straight carapace lengths (SCL) differed for the two species, Kemp's SCL=26.9 cm (n=218, range 18.4-37.2), and loggerheads SCL=52.5 cm (n=54, range 40.0-89.6). As a result, the larger sized loggerheads were able to withstand colder sea surface temperatures for longer periods of time due to greater thermoregulatory capabilities. These results demonstrate the seasonality of juvenile sea turtle cold-stunning in Cape Cod Bay, Massachusetts, providing oceanographic and climatic thresholds for the Sea Turtle Rescue and Salvage Network to maximize recovery efforts during peak cold-stunning conditions.

Volume

4

Issue

4

Pages

883-890

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