DAILY MOVEMENTS, HABITAT USE, AND SUBMERGENCE INTERVALS OF NORMAL AND TUMOR-BEARING JUVENILE GREEN TURTLES (CHELONIA-MYDAS L) WITHIN A FORAGING AREA IN THE HAWAIIAN-ISLANDS

Depth-sensitive ultrasonic transmitters monitored the horizontal and vertical movements of 12 juvenile (<65 cm carapace length) green turtles (Chelonia mydas L.) in Kaneohe Bay, Oahu (Hawaii, USA). This site was chosen because of its accessibility, its importance as a foraging area, and the high incidence (almost-equal-to 50%) of fibropapillomatosis, a tumor disease of unknown etiology. Our objectives were to determine the daily movements, habitat use, and submergence intervals of normal and tumor-bearing animals. The presence of tumors had no obvious effects on movement patterns or habitat use. All turtles remained within a small portion of the bay where patch reefs and shallow coral-covered areas are common, and algal growth most abundant. During daylight, two normal and two tumor-bearing animals remained within known feeding areas, all other turtles studied stayed within deep mud bottom channels or within crevices on the sides of reefs. All, except one tumor-bearing turtle, moved up on to shallow patch reefs or shallow coral-covered areas at night. Submergence intervals for both groups were short (over 90% were 33 min or less and none exceeded 66 min) compared to maximum breath-hold times (up to 5 h) measured in the laboratory by earlier workers. Juvenile green turtles in Hawaii, therefore, most likely maintain aerobic metabolism while submerged and surface before oxygen stores are significantly depleted. Tumor-bearing turtles had a higher frequency of longer submergence intervals during the night, indicating they may have been somewhat less active at night. Normal turtles showed no such day-night difference.