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The influence of mesoscale features on the distribution and the diving behaviour of sea turtles nesting in French Guiana

Last update: : Monday 19 October 2015, by Nicolas Busser

Par : Philippine Chambault, IPHC-DEPE, CNRS, Strasbourg
Date : Jeudi 19 novembre 2015 à 13h30
Lieu : IPHC, Amphithéâtre Grünewald, bâtiment 25

Driven by complex physical and biological processes, the marine environment is highly heterogeneous leading to resources partitioning at spatial and temporal scale. To adapt to such patchiness, sea turtles have developed migration strategies from their nesting sites to their foraging grounds. In most nesting sites, the lack of resources associated with the energy required for oviposition constrain turtles to minimize their energy expenditure and stop feeding during the egg laying season. To replenish the body reserves after this energy-demanding period, sea turtles migrate in areas under the influence of mesoscale features (eddies, fronts, etc.) and then forage in highly productive habitats in order to maximize their foraging efficiency. Assessing the dispersal movements and the habitat used by migrating animals is a key component to understand their ecology and implement adequate conservation policies, especially when dealing with vulnerable or endangered species.

By hosting each year thousands of gravid females, French Guiana is one of the major rookery of the North-eastern coast of South America for 3 of the 7 sea turtles species of the world i.e. leatherback (Dermochelys coriacea), olive ridley (Lepidochelys olivacea) and green turtles (Chelonia mydas). Under the influence of tides, the Amazon River plume and oceanic currents, the Guiana’s region is one of the world’s most dynamic ecosystem, leading to specific environmental and hydrodynamic conditions. Therefore, this study aims to identify the environmental factors affecting the distribution and the diving behaviour of sea turtles during the migration period. To do so, we deployed 30 satellite tags on adult females in French Guiana and Suriname to inform both on their ecology (on-land and at-sea) and on the oceanographic conditions encountered during their displacements. This large dataset will provide detailed and complete knowledge of the ecology of the sea turtles nesting in French Guiana since these 3 species have different diet and use diverse ecological niches at sea.

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P. Chambault equips sea turtles with data loggers to study their diving behaviour