Title:

Variables affecting the thermal ecology of loggerhead sea turtle nests during the period of sex  determination.

Abstract

Temperature dependent sex determination is a process used by sea turtles that allows incubation temperature to determine the sex of offspring in a nest. For loggerhead sea turtles (Caretta caretta) the pivotal temperature of a nest at the time when sex determination occurs (also known as the critical period) is 29.0 ^oC. If the temperature in the nest is higher than 29.0 ^oC the nest will be mainly female. If it is lower, the nest will be mainly male. Many factors play a part in determining the incubation temperature of a sea turtle nest. Ambient weather, depth of nest, and number of eggs in a nest are a few of the factors that affect nest temperature, and also the variables tested in this study.

Data on mid-nest temperatures, depth, and number of eggs from 1985 to 1989 were used. Several different single factor Analyses of Variance were used to determine significant differences in these variables when compared to each other. Mid-nest critical period temperatures varied significantly between years and mid-nest depth varied significantly between years as well as by temperature. As mid-nest depth increased temperature decreased. Other factors, such as number of eggs, were not significant. Determining which variables played a significant role in incubation temperature of loggerhead sea turtle nests shows which factors should be more closely monitored during conservation efforts to produce a viable ratio of males:females produced, thus ensuring the continuance of sea turtle populations in the future.