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Numerical dispersal simulations and genetics help explain the origin of hawksbill sea turtles in Ascension Island

TitleNumerical dispersal simulations and genetics help explain the origin of hawksbill sea turtles in Ascension Island
Publication TypeJournal Article
Year of Publication2014
AuthorsPutman, NF, F. Abreu-Grobois, A, Broderick, AC, Ciofi, C, Formia, A, Godley, BJ, Stroud, S, Pelembe, T, Verley, P, Williams, N
JournalJournal of Experimental Marine Biology and Ecology
Volume450
Pagination98–108
ISSN0022-0981
KeywordsDispersal, ocean circulation model, sea turtle, {mtDNA}
Abstract

Abstract Long-distance dispersal and ontogenetic shifts in habitat use are characteristic of numerous marine species and have important ecological, evolutionary, and management implications. These processes, however, are often challenging to study due to the vast areas involved. We used genetic markers and simulations of physical transport within an ocean circulation model to gain understanding into the origin of juvenile hawksbill sea turtles (Eretmochelys imbricata) found at Ascension Island, a foraging ground that is thousands of kilometers from known nesting beaches. Regional origin of genetic markers suggests that turtles are from Western Atlantic (86%) and Eastern Atlantic (14%) rookeries. In contrast, numerical simulations of transport by ocean currents suggest that passive dispersal from the western sources would be negligible and instead would primarily be from the East, involving rookeries along Western Africa (i.e., Principe Island) and, potentially, from as far as the Indian Ocean (e.g., Mayotte and the Seychelles). Given that genetic analysis identified the presence of a haplotype endemic to Brazilian hawksbill rookeries at Ascension, we examined the possible role of swimming behavior by juvenile hawksbills from {NE} Brazil on their current-borne transport to Ascension Island by performing numerical experiments in which swimming behavior was simulated for virtual particles (simulated turtles). We found that oriented swimming substantially influenced the distribution of particles, greatly altering the proportion of particles dispersing into the North Atlantic and South Atlantic. Assigning location-dependent orientation behavior to particles allowed them to reach Ascension Island, remain in favorable temperatures, encounter productive foraging areas, and return to the vicinity of their natal site. The age at first arrival to Ascension (4.5–5.5 years) of these particles corresponded well to estimates of hawksbill age based on their size. Our findings suggest that ocean currents and swimming behavior play an important role in the oceanic ecology of sea turtles and other marine animals.

URLhttp://www.sciencedirect.com/science/article/pii/S0022098113003675
DOI10.1016/j.jembe.2013.10.026