Dispersal and dive patterns during the post-nesting migration of olive ridley turtles from French Guiana

Abstract

Behavioral plasticity allows migrating animals to adjust their migration patterns in relation to the environmental conditions they encounter during their movements. Sea turtles display long post-nesting migrations which vary considerably between species and populations. To date, there has been no description of migratory patterns of the large population of olive ridley turtles Lepidochelys olivacea in the west Atlantic. Here, we investigated dispersal and dive patterns in relation to environmental conditions of 7 satellite-tracked olive ridley females from French Guiana during their post-nesting migration. After they left the nesting beach, turtles followed a consistent northwestward direction and then remained in the restricted yet productive neritic domain of the continental shelf of French Guiana and Suriname. Despite this restricted dispersal range, turtles demonstrated variability in the habitats they exploited, i.e. the coastline, the continental shelf, and the continental slope, illustrating some plasticity. Moreover, turtles showed 2 different foraging strategies, either directly reaching a specific foraging area off river mouths, or meandering over the neritic area exploiting several foraging areas. In addition, turtles showed different dive patterns related to their habitat, although mostly exploiting the seabed by routinely performing U-shaped benthic dives. Overall, turtles vertically exploited non-stratified water masses characterized by warm surface temperatures consistent with their preferential thermal habitat. The migration strategy used by olive ridleys from French Guiana raises conservation concerns, since turtles may be exposed to coastal human-induced activities that must be considered in the implementation of accurate management measures for this still poorly studied population.

Habitat Use and Behavior of Multiple Species of Marine Turtles at a Foraging Area in the Northeastern Gulf of Mexico

“…In contrast, CC tracked in our study seemed to prefer shallower waters (depth range 1-3.5 m), which aligns with depths reported for juvenile CC in the northern GoM (Lamont and Iverson, 2018). As observed in other studies (Seminoff et al, 2002;Plot et al, 2015;Christiansen et al, 2017), CM and CC displayed an apparent shift to shallower depths during the night, while no clear patterns were depicted for LK. However, contrary to typical diving patterns described for marine turtles which tend to have lower activity levels and undertake longer dives during nighttime (e.g., Mendonça, 1983;Hays et al, 2000;Schmid et al, 2002;Christiansen et al, 2017), our results suggest that for CM and CC the submergence times were longer and surfacing durations were shorter during daytime.…”

Informing Marine Protected Area Designation and Management for Nesting Olive Ridley Sea Turtles Using Satellite Tracking

“…Green sea turtles nesting in French Guiana similarly used the Maroni River Estuary during their internesting period (Chambault et al, 2016) but additional occurrences are not known. In the Indian Ocean, female olive ridley turtles tagged on nesting beaches in Oman display consistent coastal use (Rees et al, 2012) but other populations of olive ridley turtles have been seen to move to offshore waters adjacent to the nesting beaches or immediately end the internesting period after their last nesting event and migrate toward foraging grounds (Whiting et al, 2007;Maxwell et al, 2011;Plot et al, 2015).…”

“…Shallower depths in the estuary may result in reduced energy expenditure by turtles coming to the surface to breathe as they wait for egg development between clutches. During their time in the estuary, the olive ridley turtles appear to be utilizing the bottom habitat with U-shaped dives, which are likely related to resting or foraging (Figures 3, 5, Plot et al, 2015). In addition, turtles may find increased foraging opportunities in the estuary; whether olive ridley turtles forage during the internesting period is unclear, but some turtles remained in the estuary long after nesting was completed, suggesting that they were likely taking advantage of available resources, as has been hypothesized in other regions (Rees et al, 2012).…”

“…Presently, little is known about dive behavior of olive ridley turtles and even less is known about their dive behavior during the internesting period. The only olive ridley turtle dive studies are from the West Atlantic and focus on post-nesting dive behavior (Plot et al, 2015). Understanding how olive ridley turtles use the water column is crucial to developing evidence based management plans within the MPA fishery zones.…”

New records of Lepidochelys olivacea (Eschscholtz, 1829) (Testudines, Cheloniidae) provide evidence that Uruguayan waters are the southernmost limit of distribution for the species in the western Atlantic Ocean

“…Its diet consists generally of crustaceans and other invertebrates (Reichart 1993, Bjorndal 1997, and it shows a preference for foraging near estuaries and in bays with high levels of biological productivity. Several tracking studies using satellites have confirmed large offshore movements in search of feeding areas (Polovina et al 2004, Whiting et al 2007, Plotkin 2010, Plot et al 2015.…”