Dispersal and Diving Adjustments of the Green Turtle Chelonia mydas in Response to Dynamic Environmental Conditions during Post-Nesting Migration

PLoS One. 2015 Sep 23;10(9):e0137340. doi: 10.1371/journal.pone.0137340. eCollection 2015.

Abstract

In response to seasonality and spatial segregation of resources, sea turtles undertake long journeys between their nesting sites and foraging grounds. While satellite tracking has made it possible to outline their migration routes, we still have little knowledge of how they select their foraging grounds and adapt their migration to dynamic environmental conditions. Here, we analyzed the trajectories and diving behavior of 19 adult green turtles (Chelonia mydas) during their post-nesting migration from French Guiana and Suriname to their foraging grounds off the coast of Brazil. First Passage Time analysis was used to identify foraging areas located off Ceará state of Brazil, where the associated habitat corresponds to favorable conditions for seagrass growth, i.e. clear and shallow waters. The dispersal and diving patterns of the turtles revealed several behavioral adaptations to the strong hydrodynamic processes induced by both the North Brazil current and the Amazon River plume. All green turtles migrated south-eastward after the nesting season, confirming that they coped with the strong counter North Brazil current by using a tight corridor close to the shore. The time spent within the Amazon plume also altered the location of their feeding habitats as the longer individuals stayed within the plume, the sooner they initiated foraging. The green turtles performed deeper and shorter dives while crossing the mouth of the Amazon, a strategy which would help turtles avoid the most turbulent upper surface layers of the plume. These adjustments reveal the remarkable plasticity of this green turtle population when reducing energy costs induced by migration.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animal Migration*
  • Animals
  • Atlantic Ocean
  • Diving
  • Ecosystem
  • Female
  • Herbivory
  • Hydrodynamics
  • Nesting Behavior
  • Rivers
  • Turtles / physiology*

Grants and funding

The CARET2 program was co-financed by the OP Amazonia with the European Union’s ERDF fund, the Ministry of Ecology, Sustainable Development and Energy and the French National Centre for Space Studies (CNES) and was also supported by the French Guiana Regional Council. PC's Phd Scholarship was supported by Shell (https://www.shell.fr/aboutshell/guyane.html)and CNES Guyane (http://www.cnes-csg.fr/). The authors also acknowledge the support of the project ANTIDOT (Pépinière Interdisciplinaire Guyane, Mission pour l'Interdisciplinarité, CNRS). The funders had a role in the decision to publish but had no role in study design, data collection and analysis, or preparation of the manuscript.