Body condition and physiological changes in male green turtles during breeding

Abstract

Investigations were made into the body condition, energy metabolite and endocrinal changes of male green turtles Chelonia mydas prior to and during their vernal breeding period in the southern Great Barrier Reef. Prior to migration, breeding males exhibited a higher body condition index than non-breeding males. However, during the migratory reproductive period, breeding males lost significant body condition. Concurrent with these physical changes, breeding males showed a reduction in plasma triglycerides and an increased level of total protein towards the mid- to late breeding period. The plasma steroids corticosterone and testosterone increased and decreased, respectively, during the migratory/breeding phase. The pattern of change in body condition and physiology allude to a high-activity fasting period during the migratory/breeding phase of the male green turtle's life history. These marked physiological events during breeding suggest a proximate basis for terminating seasonal reproductive events, and a potential basis for phenotypic variation in male reproductive tactics.