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This is the first known observation of underwater oviposition by a wild sea turtle in Guadeloupe. Although sea turtles in captivity have been known to discharge eggs in the water from time to time (B. Godley, pers. comm; C. Baptistotte, pers. comm.), we know of no published references to wild sea turtles laying eggs while in the ocean. Indeed, for all turtle species, successful egg incubation requires a substratum that is not perpetually flooded with water. Only one known species of turtle, Chelodina rugosa, lays its eggs underwater, but the embryos will not develop into hatchlings until after the waterline recedes below the depth of the nest and the eggs are exposed to a non-flooded environment (Kennett et al. 1993).
Reptiles apparently do not resorb un-laid oviductal eggs (Blackburn 1998). Although anecdotes abound concerning the discharge of eggs of female turtles that were disturbed or otherwise discouraged from successfully nesting on a beach, it seems unlikely that a turtle would discharge her eggs rather than seeking out another suitable area for nesting. One study that intercepted and translocated gravid loggerheads as they were emerging on their nesting beach found that females would either return to the same nesting beach or choose to nest elsewhere, sometimes traveling up to 100km before nesting again (Murphy & Hopkins-Murphy 1990). In the present case, the nearest hawksbill nesting beach (7 km distant) is Ilet Fajou (16° 21’ 730 N, 61° 35’ 630 W). This nesting beach is characterized by many shells, stones and plant roots that make both crossing of the beach by emerging female turtles and digging of the egg chamber
particularly challenging. The majority of emergence events by turtles end up in unsuccessful nesting, with some turtles making repeated attempts to nest both during a single night and across several nights (J. Chevalier & M. Roulet, pers. comm.).
In Guadeloupe, the Kap’Natirel Association coordinates the monitoring and conservation of sea turtles both on nesting beaches and in the water. In the latter case, a network of 20 different diving clubs and shops participate by recording all observations of sea turtles during scuba dives. Since 2002, standardized protocols have been established for these underwater surveys, and data collected include species, number, location, etc. The information collected is useful not only for providing an index of population abundance and
change over time, but also for recording information on in-water behavior of sea turtles in waters around Guadeloupe. In Grand Culde-Sac, underwater observations of turtles have been kept since late 2003, with at least 2 green turtles and 3 hawksbills recorded during 193 separate dives.
Acknowledgments: We are grateful to the diving clubs that voluntarily collect in-water information on sea turtles in Guadeloupe and to all the beach
patrollers. We thank Johan Chevalier for his continued efforts at marine turtle conservation in Guadeloupe and Matthew Godfrey for helping with the write up. Financial support for Kap’Natirel Association comes from the Direction Régionale de l’Environnement de Guadeloupe.
BLACKBURN, D.G. 1998. Resorption of oviductal eggs and embryos in squamate reptiles. Herpetolgical Journal 8: 65-71.
KENNETT, R., K. CHRISTIAN & D. PRITCHARD. 1993. Underwater nesting by the tropical freshwater turtle, Chelodina rugosa (Testudinata: Chelidae). Australian Journal of Zoology 41: 47-52.
MURPHY, T.M. & S.R. HOPKINS-MURPHY. 1990. Homing of translocated gravid loggerhead turtles. In: T.H. Richardson, J.I. Richardson & M. Donnelly (Compilers) Proceedings of the Tenth Annual Workshop on Sea Turtle Biology and Conservation. NOAA Technical Memorandum NMFS-SEFC-278, Miami, Florida, pp. 123-124.