Leatherback turtle movements, dive behavior, and habitat characteristics in ecoregions of the Northwest Atlantic Ocean

• Published in: PloS one 2014-03, Vol.9 (3), p.e91726-e91726
• Main Authors: Dodge, Kara L, Galuardi, Benjamin, Miller, Timothy J, Lutcavage, Molly E
• Format: Article
• Language: English
• Subjects: Animal behavior; Animal Migration; Animals; Aquatic reptiles; Atlantic Ocean; Bathymetry; Behavior; Biology and Life Sciences; Chlorophyll; Chlorophyll - biosynthesis; Coastal ecology; Coastal environments; Coastal waters; Commercial fishing; Conservation of Natural Resources; Dermochelyidae; Dermochelys coriacea; Diving - physiology; Diving - psychology; Earth sciences; Ecology and Environmental Sciences; Ecosystems; Endangered & extinct species; Environmental associations; Environmental organizations; Exploratory behavior; Feeding Behavior - physiology; Feeding Behavior - psychology; Female; Fisheries; Food Chain; Food chains; Food webs; Foraging behavior; Foraging habitats; Gulf Stream; Habitats; Male; Models, Statistical; Movement - physiology; Oceanic analysis; Oceans; Pelagic zone; Predators; Satellites; Sea surface temperature; Sea turtles; Searching; Singers; Spring; Studies; Surface temperature; Telemetry; Temperature; Temperature effects; Temperature gradients; Turtles - physiology; Water depth; Zooplankton; Zooplankton - physiology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0091726

Leatherback sea turtles, Dermochelys coriacea, are highly migratory predators that feed exclusively on gelatinous zooplankton, thus playing a unique role in coastal and pelagic food webs. From 2007 to 2010, we used satellite telemetry to monitor the movements and dive behavior of nine adult and eleven subadult leatherbacks captured on the Northeast USA shelf and tracked throughout the Northwest Atlantic. Leatherback movements and environmental associations varied by oceanographic region, with slow, sinuous, area-restricted search behavior and shorter, shallower dives occurring in cool (median sea surface temperature: 18.4°C), productive (median chlorophyll a: 0.80 mg m(-3)), shallow (median bathymetry: 57 m) shelf habitat with strong sea surface temperature gradients (median SST gradient: 0.23°C km(-1)) at temperate latitudes. Leatherbacks were highly aggregated in temperate shelf and slope waters during summer, early fall, and late spring and more widely dispersed in subtropical and tropical oceanic and neritic habitat during late fall, winter and early spring. We investigated the relationship of ecoregion, satellite-derived surface chlorophyll, satellite-derived sea surface temperature, SST gradient, chlorophyll gradient and bathymetry with leatherback search behavior using generalized linear mixed-effects models. The most well supported model showed that differences in leatherback search behavior were best explained by ecoregion and regional differences in bathymetry and SST. Within the Northwest Atlantic Shelves region, leatherbacks increased path sinuosity (i.e., looping movements) with increasing SST, but this relationship reversed within the Gulf Stream region. Leatherbacks increased path sinuosity with decreasing water depth in temperate and tropical shelf habitats. This relationship is consistent with increasing epipelagic gelatinous zooplankton biomass with decreasing water depth, and bathymetry may be a key feature in identifying leatherback foraging habitat in neritic regions. High-use habitat for leatherbacks in our study occurred in coastal waters of the North American eastern seaboard and eastern Caribbean, putting turtles at heightened risk from land- and ocean-based human activity.