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Integrated ecology of sea turtles

Final Activity Report Summary - IEOST (Integrated Ecology Of Sea Turtles)

The aim of this integrated project was the application of state-of-the-art technologies to the study of nesting ecology and conservation of threatened sea turtle nesting populations in the Dominican Republic (DR), a country where there has been a paucity of work despite a clear conservation need. Based on previous studies and interviews with local people and Dominican academic and conservation institutions, sea turtle nesting populations seemed to have been depleted within the DR. Moreover, despite the existing legislation protecting these species, turtles and their eggs were harvested for consumption or commercial use. The study of reproductive biology, phylogeography and habitat linkages of sea turtle species nesting in the DR would allow for the determination of their conservation status and help to promote adequate conservation measures.

The project team was successful in expanding the knowledge on these threatened populations in all bespoke study areas, although analysis and writing were still being completed by the end of the project.

A three year nationwide data series on nesting frequency was secured and future work was already planned, so as to extend these data series and more fully ascertain population levels, conservation status and trends. The present project highlighted that the most important rookeries in the DR were concentrated in the southwest, i.e. in the ‘Parque Nacional Jaragua’, for the leatherback sea turtle, namely dermochelys coriacea, and in the southeast, in the ‘Parque Nacional del Este’, for the hawksbill turtle, termed as eretmochelys imbricata. Another important result was the confirmation of a third sea turtle species still nesting in the country, the green sea turtle chelonia mydas, previously considered as extirpated. Seasonality was also determined for all sea turtle species. The leatherback nesting season was from March to August, with a peak in May, and, even though the other two species seemed to nest throughout the year, the hawksbill nesting seasons had a peak during the summer months, from July to September.

Within the activities of the project, tissue samples from hatchlings of all three species were collected and mitochondrial deoxyribonucleic acid (MtDNA) analyses were in progress to provide insight into the global phylogeography of the nesting stocks. Results would help to identify the spatial extent of management units.

In order to highlight the key habitat linkages and describe the migratory routes of the hawksbill turtle from the DR we tagged eight nesting females after nesting in Saona Island and other locations of the southeast coast of the country. Another two transmitters were in the field, ready to be applied, by the time of the project completion. The tracks showed a dispersal of the turtles after nesting, with one travelling to the east, one travelling towards north surrounding the east coast of the DR, four others travelling to the west and, finally, two remaining in different locations of the south coast of DR. The integration of movement data with oceanographic datasets was underway by the reporting time.

The electronic monitoring of temperatures in artificially incubated nests and their comparison with beach temperatures allowed for an evidence-based assessment of this conservation measure, which was undertaken for decades in Parque Nacional Jaragua to avoid human predation of clutches. It seemed that the sex ratio produced in incubated clutches was biased to males, while most sea turtle nesting beaches exhibited a female-biased sex ratio. The project also contributed to the development of artificial incubation of clutches and the creation of a hatchery in the most important nesting area for hawksbills, i.e. in the Saona Island, located in the Parque Nacional del Este. Temperature monitoring and hatching success studies resulted in an MSc thesis, entitled ‘Evidence based conservation in sea turtles: An investigation into the efficacy of nest incubation of the leatherback turtle (dermochelys coriacea) in Dominican Republic’, which was co-supervised by the fellow. Another MSc thesis, elaborated in 2009, compared hatching success and incubation temperature among seasons. A third MSc thesis, also supervised by the fellow, developed the same research on the hawksbill turtle clutches.

The preliminary results on nesting, hatching success and sex ratio were presented in the 14th European Congress of Herpetology, the 28th Annual Symposium on Sea Turtle Biology and Conservation and the 6th Congress of Caribbean Biodiversity. The planned publications included four papers, on nesting biology and status, genetics, telemetry and hatchery management and sex-ratio respectively.

Apart from of the obtained scientific results, the project was instrumental in building capacity in the Dominican students, local communities and European students of the University of Exeter and the University of Valencia, Spain, as well as in the fellow himself. The training received on techniques such as genetics, satellite telemetry and population modelling with the marine turtle research group at the University of Exeter in Cornwall, UK, resulted in the acquisition of expertise in marine ecology and conservation. Moreover, it resulted in the ability to undertake new projects that contributed to the conservation on these and other threatened species. External funding was also pursued in order to continue with the work in the Dominican Republic beyond the project lifetime.