Table_2_Variation in Species Composition, Size and Fitness of Two Multi-Species Sea Turtle Assemblages Using Different Neritic Habitats.docx

The neritic environment is rich in resources and as such plays a crucial role as foraging habitat for multi-species marine assemblages, including sea turtles. However, this habitat also experiences a wide array of anthropogenic threats. To prioritize conservation funds, targeting areas that support multi-species assemblages is ideal. This is particularly important in the Gulf of Mexico where restoration actions are currently ongoing following the Deepwater Horizon oil spill. To better understand these areas in the Gulf of Mexico, we characterized two multi-species aggregations of sea turtles captured in different neritic habitats. We described species composition and size classes of turtles, and calculated body condition index for 642 individuals of three species captured from 2011 to 2019: 13.6% loggerheads (Caretta caretta), 44.9% Kemp’s ridleys (Lepidochelys kempii) and 41.4% green turtles (Chelonia mydas). Species composition differed between the two sites with more loggerheads captured in seagrass and a greater proportion of green turtles captured in sand bottom. Turtles in sand bottom were smaller and weighed less than those captured in seagrass. Although small and large turtles were captured at both sites, the proportions differed between sites. Body condition index of green turtles was lower in sand habitat than seagrass habitat; there was no difference for Kemp’s ridleys or loggerheads. In general, smaller green turtles had a higher body condition index than larger green turtles. We have identified another habitat type used by juvenile sea turtle species in the northern Gulf of Mexico. In addition, we highlight the importance of habitat selection by immature turtles recruiting from the oceanic to the neritic environment, particularly for green turtles.

浅海生境（neritic environment）资源丰饶，是包含海龟在内的多物种海洋集群的核心觅食栖息地。然而，该生境亦面临多样的人为活动威胁。为优化保护资金的分配优先级，优先划定支持多物种集群的区域为最优策略，这一点在墨西哥湾尤为关键——该区域在“深水地平线”（Deepwater Horizon）漏油事件后目前正推进生态修复工作。为进一步明晰墨西哥湾的此类区域，本研究对采自两种不同浅海生境的海龟多物种集群开展特征解析：记录了海龟的物种组成与体型分级，并对2011至2019年间捕获的3个物种共642只个体计算了身体状况指数，其中蠵龟（Caretta caretta）占比13.6%、肯氏丽龟（Lepidochelys kempii）占比44.9%、绿海龟（Chelonia mydas）占比41.4%。两个采样点的物种组成存在显著差异：海草生境中捕获的蠵龟数量更多，而沙质底栖生境中绿海龟的占比更高。沙质底栖生境中的海龟体型较海草生境中的个体更小、体重更轻；尽管两个采样点均捕获了小型与大型海龟，但二者的占比存在位点差异。沙质底栖生境中绿海龟的身体状况指数显著低于海草生境中的个体，而肯氏丽龟与蠵龟的身体状况指数则无生境间差异。总体而言，小型绿海龟的身体状况指数高于大型绿海龟。本研究明确了墨西哥湾北部幼海龟种群所利用的另一类生境类型；此外，我们强调了从远洋生境迁入浅海生境的亚成体海龟的生境选择的重要性，这一点对绿海龟而言尤为关键。