Ascension Island green turtles migrations

Paolo Luschi

doi:10.15468/fxrstj

Ascension Island green turtles migrations

Citation

Luschi, P. 2013. Ascension Island green turtles migrations. Data downloaded from OBIS-SEAMAP (http://seamap.env.duke.edu/dataset/994) on yyyy-mm-dd. https://doi.org/10.15468/fxrstj accessed via GBIF.org on 2024-12-12.

Description

Original provider: Paolo Luschi, University of Pisa, Italy; Graeme Hays, Swansea University, UK; and Susanne Akesson, und University, Sweden Dataset credits: Paolo Luschi, University of Pisa, Italy; Graeme Hays, Swansea University, UK; and Susanne Akesson, und University, Sweden Abstract: Previous tagging studies of the movements of green turtles (Chelonia mydas) nesting at Ascension Island have shown that they shuttle between this remote target in the Atlantic Ocean and their feeding grounds on the Brazilian coast, a distance of 2300 km or more. Since knowledge of sea turtle migration routes might allow inferences on the still unknown navigational mechanisms of marine animals, we tracked the postnesting migration of six green turtle females from Ascension Island to Brazil. Five of them reached the proximity of the easternmost stretch of the Brazilian coast, covering 1777-2342 km in 33-47 days. Their courses were impressively similar for the first 1000 km, with three turtles tracked over different dates following indistinguishable paths for the first 300 km. Only the sixth turtle made some relatively short trips in different directions around Ascension. The tracks show that turtles (i) are able to maintain straight courses over long distances in the open sea; (ii) may perform exploratory movements in different directions; (iii) appropriately correct their course during the journey according to external information; and (iv) initially keep the same direction as the west-south-westerly flowing current, possibly guided by chemical cues. Purpose: Luschi et al. (1998) reconstructed the routes followed by turtles leaving the island for their postnesting migration, to evaluate their navigational performance. This would then allow a re-examination of the hypotheses so far proposed about the navigational system used by these turtles to pinpoint Ascension, assuming that the same mechanisms guide the postnesting migration as well. Results show that Ascension turtles use information picked up en route to adjust their migratory course, and suggest that current-borne cues, probably of a chemical nature, may be involved in this process for at least part of the journey. Papi et al. (2000) reports the results of an experiment aimed to test the geomagnetic hypothesis by applying a magnetic disturbance to Ascension turtles returning to Brazil. If this disturbance were to impair the orientation of the turtles, this interesting hypothesis would receive its first experimental support. However, the results obtained show that magnetic cues are not essential for oceanic navigation by adult turtles migrating to Brazil.

Purpose

Luschi et al. (1998) reconstructed the routes followed by turtles leaving the island for their postnesting migration, to evaluate their navigational performance. This would then allow a re-examination of the hypotheses so far proposed about the navigational system used by these turtles to pinpoint Ascension, assuming that the same mechanisms guide the postnesting migration as well. Results show that Ascension turtles use information picked up en route to adjust their migratory course, and suggest that current-borne cues, probably of a chemical nature, may be involved in this process for at least part of the journey. Papi et al. (2000) reports the results of an experiment aimed to test the geomagnetic hypothesis by applying a magnetic disturbance to Ascension turtles returning to Brazil. If this disturbance were to impair the orientation of the turtles, this interesting hypothesis would receive its first experimental support. However, the results obtained show that magnetic cues are not essential for oceanic navigation by adult turtles migrating to Brazil.

Sampling Description

Study Extent

NA

Sampling

NA

Method steps

NA

Additional info

marine, harvested by iOBIS

Taxonomic Coverages

Scientific names are based on the Integrated Taxonomic Information System (ITIS).

Chelonia mydas
common name: Green Sea Turtle rank: species

Geographic Coverages

Oceans

Bibliographic Citations

Contacts

Paolo Luschi
originator
position: Primary contact
University of Pisa
email: pluschi@biologia.unipi.it

OBIS-SEAMAP
metadata author
Marine Geospatial Ecology Lab, Duke University
A328 LSRC building
Durham
27708
NC
US
email: seamap-contact@duke.edu
homepage: http://seamap.env.duke.edu

OBIS-SEAMAP
distributor
Marine Geospatial Ecology Lab, Duke University
A328 LSRC building
Durham
27708
NC
US
email: seamap-contact@duke.edu
homepage: http://seamap.env.duke.edu

Paolo Luschi
owner
position: Primary contact
University of Pisa
email: pluschi@biologia.unipi.it

Paolo Luschi
administrative point of contact
position: Primary contact
University of Pisa
email: pluschi@biologia.unipi.it