Lalire Maxime, Gaspar Philippe
Sustainable Management of Marine Ressources, Collecte Localisation Satellites, Ramonville Saint-Agne, France.
Mov Ecol. 2019 Feb 28;7:7. doi: 10.1186/s40462-019-0149-5. eCollection 2019.
The Northwest Atlantic (NWA) leatherback turtle () subpopulation is one of the last healthy ones on Earth. Its conservation is thus of major importance for the conservation of the species itself. While adults are relatively well monitored, pelagic juveniles remain largely unobserved. In an attempt to reduce this knowledge gap, this paper presents the first detailed simulation of the open ocean dispersal of juveniles born on the main nesting beaches of French Guiana and Suriname (FGS).
Dispersal is simulated using STAMM, an Individual Based Model in which juveniles actively disperse under the combined effects of oceanic currents and habitat-driven movements. For comparison purposes, passive dispersal under the sole effect of oceanic currents is also simulated.
Simulation results show that oceanic currents lead juveniles to cross the Atlantic at mid-latitudes. Unlike passive individuals, active juveniles undertake important north-south seasonal migrations while crossing the North Atlantic. They finally reach the European or North African coast and enter the Mediterranean Sea. Less than 4-year-old active turtles first arrive off Mauritania. Other productive areas on the eastern side of the Atlantic (the coast of Galicia and Portugal, the Gulf of Cadiz, the Bay of Biscay) and in the Mediterranean Sea are first reached by 6 to 9-year-old individuals. This active dispersal scheme, and its timing, appear to be consistent with all available stranding and bycatch data gathered on the Atlantic and Mediterranean coasts of Europe and North Africa. Simulation results also suggest that the timing of the dispersal and the quality of the habitats encountered by juveniles can, at least partly, explain why the NWA leatherback subpopulation is doing much better than the West Pacific one.
This paper provides the first detailed simulation of the spatial and temporal distribution of juvenile leatherback turtles dispersing from their FGS nesting beaches into the North Atlantic Ocean and Mediterranean Sea. Simulation results, corroborated by stranding and bycatch data, pinpoint several important developmental areas on the eastern side of the Atlantic Ocean and in the Mediterranean Sea. These results shall help focus observation and conservation efforts in these critical areas.
西北大西洋棱皮龟亚种群是地球上最后一批健康的亚种群之一。因此，对该亚种群的保护对于物种本身的保护至关重要。虽然成年棱皮龟受到了相对较好的监测，但远洋幼龟在很大程度上仍未被观察到。为了缩小这一知识差距，本文首次详细模拟了在法属圭亚那和苏里南（FGS）主要筑巢海滩出生的幼龟在公海中的扩散情况。
使用基于个体的模型STAMM模拟扩散，在该模型中，幼龟在洋流和栖息地驱动的运动共同作用下进行主动扩散。为了进行比较，还模拟了仅在洋流作用下的被动扩散。
模拟结果表明，洋流导致幼龟在中纬度地区穿越大西洋。与被动扩散的个体不同，主动扩散的幼龟在穿越北大西洋时会进行重要的南北季节性迁徙。它们最终到达欧洲或北非海岸并进入地中海。年龄小于4岁的主动扩散海龟首先抵达毛里塔尼亚近海。6至9岁的个体首先到达大西洋东侧（加利西亚和葡萄牙海岸、加的斯湾、比斯开湾）和地中海的其他高产区域。这种主动扩散模式及其时间似乎与在欧洲和北非大西洋及地中海沿岸收集到的所有可用搁浅和兼捕数据一致。模拟结果还表明，扩散时间和幼龟遇到的栖息地质量至少可以部分解释为什么西北大西洋棱皮龟亚种群比西太平洋棱皮龟亚种群的情况要好得多。
本文首次详细模拟了从FGS筑巢海滩扩散到北大西洋和地中海的棱皮龟幼龟的时空分布。模拟结果得到搁浅和兼捕数据的证实，确定了大西洋东侧和地中海的几个重要发育区域。这些结果将有助于在这些关键区域集中观测和保护工作。
