Trophic ecology of green sea turtles in a highly urbanized bay: Insights from stable isotopes and mixing models
Trophic ecology of green sea turtles in a highly urbanized bay: Insights from stable isotopes and mixing models
复制标题
DOI：
10.1016/j.jembe.2011.05.012
复制
发表时间：
2011-08-31
影响因子：
2
通讯作者：
Seminoff, Jeffrey A.
中科院分区：
文献类型：
--
作者：
Lemons, Garrett;Lewison, Rebecca;Seminoff, Jeffrey A.
绿色海龟Chelonia mydas是一种环球物种，易受过度开发作为食物资源，渔业意外死亡，沿海觅食栖息地退化，所有这些都有助于将其列入世界自然保护联盟红色名录中的濒危物种。由于缺乏关于海龟生物学的信息，恢复区域绿色海龟种群的努力受到阻碍。特别是，在浅海觅食区的饮食摄入量和栖息地利用的时间模式还没有得到很好的理解。历史范例表明，成年绿色海龟是专性食草动物，饮食由海草和/或海藻组成。然而，这些见解在很大程度上是基于传统的饮食分析技术，只产生最近消费的食物的快照。稳定同位素分析已被用于确定各种潜在的食物资源对消费者饮食的贡献，这种方法通常用于确定饮食组成和物种的长期营养关系。在这项研究中，我们测量了86只绿色海龟和7种假定的猎物物种（例如，藻类、海草、无脊椎动物），2003年至2008年在美国加州圣地亚哥湾采集，圣地亚哥湾是温带东太平洋的城市化沿海海湾。在本研究中，绿色海龟皮肤中的δ C-13和δ N-15值分别为-18.9 ‰至-13.7 ‰和11.0 ‰至19.3 ‰，而潜在食物的δ C值范围为-22.6 ‰至-11.5 ‰，13和10.4ppm至15.9ppm。我们采用了领先的多光谱稳定同位素混合模型（R中的稳定同位素分析），以确定的主要贡献者，和年度变化，绿色海龟饮食的基础上比较的同位素值的海龟和假定的猎物物种。混合模型的输出表明，绿色海龟消耗杂食性饮食在本研究的所有年份。移动的无脊椎动物的饮食分布中位数最大（38%），而海草（26%）和固着无脊椎动物（12%）也被认为是主要的饮食贡献者。红藻和绿色藻类也被确定为可行的猎物物种，尽管数量有所减少。当与猎物物种的空间分布信息相结合时，这些数据还提供了关于觅食绿色海龟所访问的栖息地类型的见解。当地的海草牧场似乎具有很高的价值，是一种主要的食物资源，并为其他绿色海龟猎物提供栖息地。因此，保护圣地亚哥湾及其周围的剩余海草栖息地被认为是当地绿色海龟管理的关键，在这个高度城市化的海湾退化的海草栖息地的恢复应被视为一个首要的保护优先事项。由爱思唯尔公司出版
The green turtle, Chelonia mydas, is a circumglobal species that is susceptible to overexploitation as a food resource, incidental mortality in fisheries, and coastal foraging habitat degradation, all of which have contributed to its listing as Endangered on the IUCN Red List. Efforts to recover regional green turtle populations have been hampered by a lack of information on their biology. In particular, temporal patterns of diet intake and habitat use in neritic foraging areas are not well understood. Historical paradigms suggest that adult green turtles are obligate herbivores with diets consisting of seagrasses and/or marine algae. However, these insights are largely based on conventional diet analysis techniques that only yield snapshots of recently consumed foods. Stable isotope analysis has been used to determine contributions of various potential food resources to a consumer's diet, and this approach is commonly applied to identify diet composition and long-term trophic relationships of a species. In this study, we measured the stable carbon (delta C-13) and nitrogen (delta N-15) isotope values of 86 green turtles and seven putative prey species (e.g., algae, seagrass, invertebrates) collected from 2003 to 2008 in San Diego Bay, California, USA, an urbanized coastal bay in the temperate eastern Pacific Ocean. The delta C-13 and delta N-15 values in skin of green turtles in this study ranged from -18.9 parts per thousand to -13.7 parts per thousand and 11.0 parts per thousand to 19.3 parts per thousand, respectively, whereas the values for potential foods ranged from -22.6 parts per thousand to -11.5 parts per thousand for delta C-13 and 10.4 parts per thousand to 15.9 parts per thousand for delta N-15. We applied a leading multisource stable isotope mixing model (Stable Isotope Analysis in R), to determine the main contributors to, and annual variation in, green turtle diet based on comparisons of isotope values of turtles and putative prey species. Mixing model outputs indicated that green turtles consumed an omnivorous diet during all years of this study. Mobile invertebrates had the greatest median dietary distribution (38%), whereas seagrasses (26%) and sessile invertebrates (12%) were also found to be major dietary contributors. Red algae and green algae were also identified as feasible prey species, although at reduced levels. When coupled with information on prey species' spatial distributions, these data also provide insights about the types of habitats visited by foraging green turtles. Local seagrass pastures appear to be of high value, serving as a major food resource and providing habitat for other green turtle prey. Protection of the remaining seagrass habitat in and around San Diego Bay is thus considered essential for local green turtle management, and restoration of degraded seagrass habitats in this highly urbanized bay should be considered a top conservation priority. Published by Elsevier B.V.