Sea turtles face various threats from a vast number of natural predators, however it is the impact of human activities which have threatened their survival the most. Bycatch from the industrial fishing fleets, loss of nesting habitat due to beach development and poaching for their products (i.e tortoiseshell) or direct human consumption, have threatened all sea turtle populations, pushing some to the brink of extinction. Many conservation programs, governments, scientists and concerned citizens alike have been working to help save these animals by developing stewardship programs, new technologies (i.e. Turtle Excluding Devices which prevent trawling by-catch) and protective laws.

However a new threat has arisen which could counteract these successful efforts – global warming. As reptiles, sea turtles are more susceptible to changes in their thermal surroundings since they regulate their body temperature environmentally rather than metabolically. Furthermore, sea turtles exhibit temperature-sex-determination (TSD). That is, the sex of the hatchling is determined from the temperature it experiences as a developing egg in the nest. Warmer temperatures produce females and cooler temperatures produce males with intermediary temperatures producing mixed ratios of both sexes. Incubating sea turtle eggs also have upper lethal limits - if sand temperatures become too hot, embryogenesis will not succeed. Thus, with increasing climatic temperatures beaches face either feminization – all hatchlings produced are female, or ultimately - fatality due to lethal temperatures.

Another problem from climate change that sea turtles face is rising sea level from glacial melting due to increasing temperatures. If the beach has nowhere to progress landwards, significant nesting habitat may be lost completely. This is of particular concern in the Caribbean as most beaches are at low-lying elevations and human development prevents inward progression.

As sea turtles nest on the beach they were born on, high nest productivity is the major source of recruitment for a population. In other words, little to no recruitment results from individuals migrating from other populations. Thus, loss of suitable nesting ground in addition to beach feminization, could lead to complete population failure in localized areas.

Costa Rican beaches are not exempt from these potential problems. So what can we do to help prevent these potential problems from affecting these magnificent animals in Costa Rica? COTERC, in partnership with McMaster University, will begin a three year research project starting in Feb. 2009 to address these issues. Investigations into the current sex ratios being produced and mapping potential nesting habitat loss using GIS technology will begin. This research will allow for conservation policies and strategies to be developed and implemented before the problems arise, helping us to continue to protect these magnificent animals.

I would like to acknowledge COTERC for providing logistical support and the Donner Canadian Foundation for funding this important project, and my advisor Dr. Patricia Chow-Fraser, Office of Research Services, McMaster University.

April Stevens

Originally Published in Raphia Winter 2009