Distribution and temporal trends in the abundance of nesting sea turtles in the Red Sea

Mobile species often aggregate at predictable places and times to ensure that individuals find mates and breed in suitable habitats. Sea turtles demonstrate this life history trait, which can make these species highly susceptible to population declines if nesting habitats are lost or degraded. Conservation management thus requires knowledge of where and when turtles nest and changes in abundance in these habitats through time. Here, we compiled new and published data and used a novel analysis to describe seasonality, annual abundance and spatial distribution of nesting green (Chelonia mydas) and hawksbill (Eretmochelys imbricata) turtles in data-deficient populations that inhabit the Red Sea. Major new rookeries were identified for green turtles at Jazirat1 Mashabah (113 and 179 nesting females in 2018 and 2019) and for hawksbill turtles at Jazirat Al Waqqadi (79 nesting females in 2018), both of which are located on nearshore islands of the Kingdom of Saudi Arabia in an area subject to industrial, residential and ecotourism developments. An upward trend in annual abundance of nesting sea turtles was estimated at some sites including Ras Al Baridi (Saudi Arabia), a major rookery of green turtles in the Red Sea, where the annual numbers increased from 14–110 individuals in 1982–1995 to 178 and 330 individuals in 2018 and 2019. This integrative work provides the most up-to-date, comprehensive information on nesting sea turtles in the Red Sea and documents a critical baseline for sea turtle conservation and future management effort.

具有移动性的物种通常会在可预测的地点与时段集群，以保障个体能够找到配偶并在适宜的栖息地完成繁殖。海龟便具备这一生活史特征，这意味着若筑巢栖息地遭到破坏或退化，这类物种极易出现种群数量下降的情况。因此，海龟保护管理工作需要掌握海龟的筑巢地点、时段，以及这些栖息地内种群数量随时间的变化情况。本研究整合了全新数据与已发表文献数据，并采用创新性分析方法，对栖息于红海、数据匮乏的绿海龟（Chelonia mydas）及玳瑁（Eretmochelys imbricata）的筑巢种群的季节节律、年度数量与空间分布特征进行了描述。研究在沙特阿拉伯王国近岸海域的两处受工业、住宅及生态旅游开发影响的区域，分别发现了绿海龟的重要新筑巢群——贾齐拉特·马沙巴岛（2018年、2019年分别有113只、179只筑巢雌龟），以及玳瑁的重要新筑巢群——贾齐拉特·瓦卡迪岛（2018年有79只筑巢雌龟）。部分监测位点的筑巢海龟年度数量呈现上升趋势，其中包括红海绿海龟的重要筑巢群所在地沙特阿拉伯拉斯·阿尔·巴里迪：其年度筑巢个体数已从1982-1995年的14-110只，增长至2018年的178只与2019年的330只。本项整合研究为红海筑巢海龟提供了目前最全面、最新的调研数据，并为海龟保护及未来管理工作确立了关键基准基线。