van Deurs Mikael, Persson Anders, Lindegren Martin, Jacobsen Charlotte, Neuenfeldt Stefan, Jørgensen Christian, Nilsson P Anders
Department of Biology - Aquatic Ecology Lund University Ecology Building SE-223 62 Lund Sweden; National Institute for Aquatic resources - Section for Marine Living Resources Technical University of Denmark Jægersborgs alle 1DK-2920 Charlottenlund Denmark.
Department of Biology - Aquatic Ecology Lund University Ecology Building SE-223 62 Lund Sweden.
Ecol Evol. 2016 May 19;6(12):4076-87. doi: 10.1002/ece3.2167. eCollection 2016 Jun.
Accumulating research argues that migrants influence the functioning and productivity of local habitats and ecosystems along migration routes and potentially drive cross-system energy fluxes of considerable magnitude, yet empirical documentation of local ecological effects and descriptions of the underlying mechanisms are surprisingly rare. In this study, we discovered migrant-resident interactions and substantial cross-system lipid transportation in the transition zone between the Baltic Sea and the North Sea where a resident cod population (predators) was found to interact with a herring population (prey) on a seasonal basis. We traced the lipids, using fatty acid trophic markers (FATM), from the herring feeding grounds in the North Sea to the cod livers in the Western Baltic Sea. Time series analysis of population dynamics indicated that population-level production of cod is positively affected by the herring subsidies. However, the underlying mechanisms were more complicated than anticipated. During the herring season, large cod received most of its dietary lipids from the herring, whereas smaller cod were prevented from accessing the lipid pool due to a mismatch in predator-prey size ratio. Furthermore, while the herring were extremely rich in bulk energy, they were surprisingly poor in a specific functional fatty acid. Hence, our study was the first to illustrate how the magnitude cross-system fluxes of subsidies in migrant-resident systems are potentially constrained by the size structure of the resident predator population and the nutritional quality of the migrants.
越来越多的研究表明，迁徙动物会影响沿迁徙路线的当地栖息地和生态系统的功能及生产力，并可能推动规模可观的跨系统能量流动，然而，关于当地生态影响的实证记录以及对潜在机制的描述却出奇地少见。在本研究中，我们在波罗的海和北海之间的过渡区域发现了迁徙动物与定居动物之间的相互作用以及大量的跨系统脂质运输，在该区域，一个定居的鳕鱼种群（捕食者）被发现与一个鲱鱼种群（猎物）存在季节性相互作用。我们利用脂肪酸营养标记（FATM）追踪脂质，从北海的鲱鱼觅食地到波罗的海西部的鳕鱼肝脏。种群动态的时间序列分析表明，鳕鱼的种群水平产量受到鲱鱼补贴的积极影响。然而，其潜在机制比预期的更为复杂。在鲱鱼季期间，大型鳕鱼的饮食脂质大多来自鲱鱼，而小型鳕鱼由于捕食者与猎物大小比例不匹配而无法获取脂质库。此外，虽然鲱鱼富含大量能量，但它们在一种特定的功能性脂肪酸方面却出奇地匮乏。因此，我们的研究首次阐明了迁徙动物 - 定居动物系统中补贴的跨系统通量大小如何可能受到定居捕食者种群的大小结构和迁徙动物营养质量的限制。
