Ascension Island green turtles migrations

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 (<i>Chelonia mydas</i>) 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.

Original provider:
原文提供者：
Paolo Luschi，意大利比萨大学；Graeme Hays，英国斯旺西大学；Susanne Akesson，瑞典乌普萨拉大学

Dataset credits:
数据集贡献者：
Paolo Luschi，意大利比萨大学；Graeme Hays，英国斯旺西大学；Susanne Akesson，瑞典乌普萨拉大学

Abstract:
摘要：
此前对在阿森松岛筑巢的绿海龟（<i>Chelonia mydas</i>）的追踪研究表明，它们往返于大西洋中这一偏远目标地与巴西海岸的觅食地之间，距离达2300公里或更远。由于了解海龟迁徙路线有助于推断海洋动物仍未知晓的导航机制，我们追踪了6只雌性绿海龟从阿森松岛到巴西的产卵后迁徙。其中5只到达巴西海岸最东端海域附近，在33至47天内覆盖了1777至2342公里。它们的航线在前1000公里内惊人地相似，不同日期追踪的3只海龟在前300公里内遵循着难以区分的路径。只有第6只海龟在阿森松岛周围不同方向进行了一些相对较短的移动。追踪结果显示，海龟（i）能够在开阔海域长距离保持直线航线；（ii）可能进行不同方向的探索性移动；（iii）在旅程中根据外部信息适当调整航线；（iv）最初保持与西南偏西流向洋流相同的方向，可能受化学线索引导。