Tracking marine tetrapod carcasses using a low-cost mixed methodology with GPS trackers, passive drifters, and citizen science

Drift experiments are essential to understand stranding patterns and to estimate the mortality of beached animals. Most studies do not use telemetry technology due to the high costs of this methodology. The objective of this paper is to describe the possibilities of tracking marine tetrapod carcasses with a low-cost and replicable methodology. The study was conducted in the Southern Subtropical Shelf (~ 28º–34º S), a highly productive and key ecological region of the southwestern Atlantic Ocean (SWA). We designed and tested a low-cost mixed methodology including Global Positioning System trackers, passive drifters (reused glass bottles), and Citizen Science (through instant message platform and email) for tracking carcasses of marine tetrapods. We performed four drift experiments, during the four seasons of 2019. We released 787 drifters (600 non-biological and 187 carcasses of seabirds, sea turtles, and cetaceans) at sea, at five equally separated distances (5–25 km) from the coa..., We used a commercial vehicular GPS tracker (©TKSTAR TK905, Figure S2a) to monitor the trajectories of the carcasses of sea turtles and franciscana dolphins. The device works with a GSM network and GPS satellites and can locate and monitor any remote target by Short Message Service (SMS), Application (APP), and the Internet (technical specifications are presented in Supplementary Material S1). In order to extend battery life, the device was connected to a 5000mAh power bank (©XTRAX, Figure S2c). In 2019, we conducted four drift experiments (summer, autumn, winter, and spring) in the State of Rio Grande do Sul, Southern Brazil, to refine the estimates of at-sea mortality of marine tetrapods, using a commercial vessel (length: 16m, beam: 5.5m; Figure S3). The drifters were released at sea at five points at different distances from the beach (Table S2). Points were numbered from 1 to 5 from the coast to offshore. The standard composition of drifters by release point was the following: 30 bo...,漂移实验对于阐明海洋动物搁浅规律、估算搁浅动物死亡率至关重要。受限于遥测技术的高昂实施成本，多数相关研究并未采用该方法。本研究旨在介绍一种低成本、可复现的海洋四足类（marine tetrapod）尸体追踪方法。本次实验选址于南大西洋西南部（SWA）的高生产力核心生态区域——南亚热带陆架区（约南纬28°~34°）。 我们设计并测试了一套低成本复合追踪方案，包含全球定位系统（Global Positioning System，GPS）追踪器、被动漂流浮标（复用玻璃瓶）以及公民科学（Citizen Science）模式——通过即时通讯平台与电子邮件开展协作——用于海洋四足类尸体追踪。本研究于2019年四季开展四次漂移实验，共在距海岸5~25km的五个等间距海域投放787个漂流浮标，其中600个为非生物浮标，187个为海鸟、海龟与鲸类的动物尸体浮标…… 我们采用商用车载GPS追踪器（©TKSTAR TK905，图S2a），对海龟与弗蘭西斯科納海豚（franciscana dolphin）的尸体运动轨迹进行监测。该设备依托全球移动通信系统（GSM）网络与GPS卫星运行，可通过短消息服务（SMS）、应用程序（APP）及互联网实现对任意远程目标的定位与监控（技术参数详见补充材料S1）。为延长续航时长，设备外接5000mAh移动电源（©XTRAX，图S2c）。 2019年，我们于巴西南部南里奥格兰德州开展四次漂移实验（覆盖夏季、秋季、冬季与春季），依托总长16m、型宽5.5m的商用作业船（图S3），以优化海洋四足类海上死亡率的估算精度。漂流浮标被投放于距岸距离各异的五个海域点位（表S2），点位编号从近岸到远海依次为1至5。各投放点位的浮标标准配置如下：30个……