Steibl Sebastian, Sigl Robert, Blaha Sanja, Drescher Sophia, Gebauer Gerhard, Gürkal Elif, Hüftlein Frederic, Satzger Anna, Schwarzer Michael, Seidenath Dimitri, Welfenbach Jana, Zinser Raphael S, Laforsch Christian
Department Animal Ecology I and BayCEER University of Bayreuth Bayreuth Germany.
BayCEER-Laboratory of Isotope Biogeochemistry University of Bayreuth Bayreuth Germany.
Ecol Evol. 2021 Aug 26;11(19):13128-13138. doi: 10.1002/ece3.8035. eCollection 2021 Oct.
Ecosystems are interconnected by energy fluxes that provide resources for the inhabiting organisms along the transition zone. Especially where in situ resources are scarce, ecosystems can become highly dependent on external resources. The dependency on external input becomes less pronounced in systems with elevated in situ production, where only consumer species close to the site of external input remain subsidized, whereas species distant to the input site rely on the in situ production of the ecosystem. It is largely unclear though if this pattern is consistent over different consumer species and trophic levels in one ecosystem, and whether consumer species that occur both proximate to and at a distance from the input site differ in their dependency on external resource inputs between sites. Using stable isotope analysis, we investigated the dependency on external marine input for common ground-associated consumer taxa on small tropical islands with high in situ production. We show that marine input is only relevant for strict beach-dwelling taxa, while the terrestrial vegetation is the main carbon source for inland-dwelling taxa. Consumer species that occurred both close (beach) and distant (inland) to the site of marine input showed similar proportions of marine input in their diets. This supports earlier findings that the relevance of external resources becomes limited to species close to the input site in systems with sufficient in situ production. However, it also indicates that the relevance of external input is also species-dependent, as consumers occurring close and distant to the input site depended equally strong or weak on marine input.
生态系统通过能量流相互连接，能量流为过渡带中的栖息生物提供资源。特别是在原地资源稀缺的地方，生态系统可能会高度依赖外部资源。在原地生产力较高的系统中，对外部输入的依赖变得不那么明显，在这些系统中，只有靠近外部输入地点的消费者物种仍能获得补贴，而远离输入地点的物种则依赖生态系统的原地生产。然而，目前尚不清楚这种模式在一个生态系统中的不同消费者物种和营养级上是否一致，以及在输入地点附近和远处出现的消费者物种在不同地点对外部资源输入的依赖是否存在差异。我们使用稳定同位素分析，研究了在原地生产力较高的小热带岛屿上，常见的与地面相关的消费者类群对外部海洋输入的依赖情况。我们发现，海洋输入仅与严格栖息在海滩的类群相关，而陆地植被是内陆栖息类群的主要碳源。在靠近（海滩）和远离（内陆）海洋输入地点出现的消费者物种在其饮食中显示出相似比例的海洋输入。这支持了早期的研究结果，即在原地生产力充足的系统中，外部资源的相关性仅限于靠近输入地点的物种。然而，这也表明外部输入的相关性也取决于物种，因为在靠近和远离输入地点出现的消费者对海洋输入的依赖程度相同或不同。
