Lamont Margaret M, Slone Daniel, Reid James P, Butler Susan M, Alday Joseph
U.S. Geological Survey, Wetland and Aquatic Research Center, Gainesville, FL 32653, USA.
Mov Ecol. 2024 May 30;12(1):40. doi: 10.1186/s40462-024-00480-y.
Individual variation in movement strategies of foraging loggerhead turtles have been documented on the scale of tens to hundreds of kilometers within single ocean basins. Use of different strategies among individuals may reflect variations in resources, predation pressure or competition. It is less common for individual turtles to use different foraging strategies on the scale of kilometers within a single coastal bay. We used GPS tags capable of back-filling fine-scale locations to document movement patterns of loggerhead turtles in a coastal bay in Northwest Florida, U.S.A.
Iridium-linked GPS tags were deployed on loggerhead turtles at a neritic foraging site in Northwest Florida. After filtering telemetry data, point locations were transformed to movement lines and then merged with the original point file to define travel paths and assess travel speed. Home ranges were determined using kernel density function. Diurnal behavioral shifts were examined by examining turtle movements compared to solar time.
Of the 11 turtles tagged, three tracked turtles remained in deep (~ 6 m) water for almost the entire tracking period, while all other turtles undertook movements from deep water locations, located along edges and channels, to shallow (~ 1-2 m) shoals at regular intervals and primarily at night. Three individuals made short-term movements into the Gulf of Mexico when water temperatures dropped, and movement speeds in the Gulf were greater than those in the bay. Turtles exhibited a novel behavior we termed drifting.
This study highlighted the value provided to fine-scale movement studies for species such as sea turtles that surface infrequently by the ability of these GPS tags to store and re-upload data. Future use of these tags at other loggerhead foraging sites, and concurrent with diving and foraging data, would provide a powerful tool to better understand fine-scale movement patterns of sea turtles.
在单个大洋盆地内，蠵龟觅食运动策略的个体差异已在数十至数百公里的尺度上得到记录。个体间使用不同策略可能反映了资源、捕食压力或竞争的差异。在单个沿海水湾内，个体蠵龟在公里尺度上使用不同觅食策略的情况较少见。我们使用能够回填精细尺度位置的GPS标签，记录了美国佛罗里达州西北部一个沿海水湾内蠵龟的运动模式。
将铱星连接的GPS标签部署在佛罗里达州西北部一个浅海觅食地的蠵龟身上。在过滤遥测数据后，将点位置转换为运动线，然后与原始点文件合并以定义行进路径并评估行进速度。使用核密度函数确定家域。通过将海龟运动与太阳时间进行比较来检查昼夜行为变化。
在标记的11只海龟中，3只被追踪的海龟在几乎整个追踪期间都停留在深（约6米）水中，而所有其他海龟则定期且主要在夜间从沿边缘和航道的深水位置移动到浅（约1 - 2米）滩。当水温下降时，3只个体短期进入墨西哥湾，在墨西哥湾的移动速度大于在海湾中的速度。海龟表现出一种我们称为漂移的新行为。
本研究强调了这些GPS标签存储和重新上传数据的能力为诸如海龟这类不常浮出水面的物种的精细尺度运动研究提供的价值。未来在其他蠵龟觅食地使用这些标签，并同时获取潜水和觅食数据，将为更好地理解海龟的精细尺度运动模式提供一个强大的工具。
