ABSTRACT: Cohort structure and degree of individual resource specialization affect individual- and population-level fitness and ecosystem interactions. These 2 characteristics are difficult to establish for long-lived marine species such as sea turtles. Both characteristics were approached by applying a novel Broken-Stick analysis of Stable isotope Time series (BS-SiTs) framework to longitudinal data series derived from metabolically inert carapace scute tissue of 13 loggerhead turtles Caretta caretta near the coast of Kochi prefecture, Japan. During the subadult stage, δ¹⁵N signatures decreased 1.29‰ per 50 μm scute slice away from values associated with neritic habitats and a diet of benthic invertebrates. Following a breakpoint, δ¹⁵N signatures stabilized in the range of 10-15‰, corresponding with planktonic feeding adults with an oceanic foraging strategy in the North Pacific. Ontogenetic shifts in δ¹⁵N occurred at different chronological points for each individual, implying the presence of a diverse cohort structure within the local coastal population. During the adult stage, within-individual variation in δ¹⁵N was <6.1% of the total δ¹⁵N variation among sampled individuals. To offer effective protection, management actions should account for this potentially high individual resource specialization at the scale of local coastal populations. Nesting numbers of loggerhead turtles in Japan have been declining since the 1990s. The BS-SiTs framework provides ecological baseline information on ontogenetic shifts in resource use of individuals suitable to support management plans. Specifically, when applied across multiple individuals, the BS-SiTs framework offers a low-cost, non-invasive solution to monitor and compare trends in cohort structure among local coastal populations.

中文翻译：

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红海龟的群落结构和个体资源专业化，具有个体遗传迁移的长寿海洋物种

摘要：群体结构和个体资源专业化程度影响个体和种群水平的适应度和生态系统相互作用。对于海龟等长寿海洋物种来说，这两个特征很难建立。通过对来自日本高知县海岸附近的13 只蠵龟Caretta caretta 的代谢惰性甲壳盾甲组织的纵向数据系列应用稳定同位素时间序列 (BS-SiTs) 框架的新型断棒分析，来接近这两个特征。在亚成体阶段，δ ¹⁵ N 特征与浅海栖息地和底栖无脊椎动物的饮食相关的值每 50 微米盾片切片减少 1.29‰。在断点之后，δ ¹⁵N 特征稳定在 10-15‰ 的范围内，对应于北太平洋采用海洋觅食策略的浮游成虫。δ ¹⁵ N 的个体发生变化发生在每个个体的不同时间点，这意味着当地沿海人口中存在不同的队列结构。在成年阶段，δ ¹⁵ N的个体内变异< δ ¹⁵总量的 6.1%抽样个体之间的 N 变异。为了提供有效的保护，管理行动应该考虑到当地沿海人口规模的这种潜在的高度个人资源专业化。自 1990 年代以来，日本红海龟的筑巢数量一直在下降。BS-SiTs 框架提供了关于适合支持管理计划的个人资源使用的个体发生变化的生态基线信息。具体而言，当应用于多个个体时，BS-SiTs 框架提供了一种低成本、非侵入性的解决方案，用于监测和比较当地沿海人口群体结构的趋势。