Influence of oceanographic conditions on nesting abundance, phenology and internesting periods of east Pacific green turtles
Sea turtles are migratory animals that travel from foraging grounds to specific nesting beaches every few years and that, therefore, can be influenced by oceanographic conditions in several different habitats. We assessed how sea surface temperature (SST) and chlorophyll-α (Chl-α) within both internesting and foraging areas influence the nesting abundance, phenology and duration of internesting periods of the green turtles (Chelonia mydas) that nest at Cabuyal, Northwest Costa Rica. Specifically, we compared (1) SST and Chl-α in foraging areas to the nesting abundance and median nesting date (MND) registered on the beach over seven nesting seasons and (2) SST in internesting habitats to the observed internesting period (OIP) (number of days between successful nesting events) and the MND. Nesting abundance was strongly correlated to Chl-α concentrations at the main foraging area during the February preceding the nesting season. However, we found no significant effect of SST or Chl-α in either foraging or internesting habitats on the MND. Mean SST values in the internesting habitats and OIP were negatively correlated and were highly variable both between and within years. Oceanographic conditions appear to strongly influence OIP and nesting abundance, but not the nesting phenology of green turtles in this area. The complex nature of the effect of oceanographic conditions on reproduction of the East Pacific green turtle suggests uncertainty in how this species will respond to climate change.
We would like to thank the research teams that have helped year after year to collect field nesting data at Cabuyal. This research would have been impossible without the hard work of coordinators, research assistants and volunteers. We also thank Roger Blanco and the Guanacaste Conservation Area for granting scientific permits and for their genuine interest in research. We thank Alejandro Martínez Abraín for statistical advice. Finally, we would like to thank the reviewers that helped improved the quality of the study.
This study was funded by The Leatherback Trust.
Compliance with ethical standards
Conflict of interest
All authors declare that they have no conflicts of interests.
All applicable international, national, and/or institutional guidelines for the care and use of animals were followed. Research permits were obtained by the Ministry of Environment and Energy of Costa Rica (MINAE).
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