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Ascension Island green turtles migrations
Citation
Luschi, P., G.C. Hays, C. Del Seppia, R. Marsh and F. Papi. 1998. The navigational feats of green sea turtles migrating from Ascension Island investigated by satellite telemetry. Proceedings of the Royal Society: Biological Sciences. 265: 2279-2284
Contact: Luschi, Paolo

Access data
Archived data
Availability: Creative Commons License This dataset is licensed under a Creative Commons Attribution 4.0 International License.

Description
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. more

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. This dataset is a summarized representation of the telemetry locations aggregated per species per 1-degree cell.

Scope
Themes:
Biology > Reptiles
Keywords:
Marine, ASE, Ascension I., ASW, Brazil, Chelonia mydas

Geographical coverage
ASE, Ascension I. [Marine Regions]
ASW, Brazil [Marine Regions]

Temporal coverage
27 April 1997 - 20 August 1998

Taxonomic coverage
Chelonia mydas (Linnaeus, 1758) [WoRMS]

Contributors
University of Pisa, moredata creator

Related datasets
Published in:
OBIS-SEAMAP: Spatial Ecological Analysis of Megavertebrate Populations, more

Publication
Based on this dataset:
Papi, F. et al. (2000). Open-sea migration of magnetically disturbed sea turtles. J. Exp. Biol. 203: 3435–3443, more
Luschi, P. et al. (1998). The navigational feats of green sea turtles migrating from Ascension Island investigated by satellite telemetry. Proc. - Royal Soc., Biol. Sci. 265: 2279-2284, more

Dataset status: Completed
Data type: Data
Data origin: Research: field survey
Metadatarecord created: 2015-02-19
Information last updated: 2015-02-19
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