Biotic connectivity between ecosystems can provide major transport of organic matter and nutrients, influencing ecosystem structure and productivity1, yet the implications are poorly understood owing to human disruptions of natural flows2. When abundant, seabirds feeding in the open ocean transport large quantities of nutrients onto islands, enhancing the productivity of island fauna and flora3,4. Whether leaching of these nutrients back into the sea influences the productivity, structure and functioning of adjacent coral reef ecosystems is not known. Here we address this question using a rare natural experiment in the Chagos Archipelago, in which some islands are rat-infested and others are rat-free. We found that seabird densities and nitrogen deposition rates are 760 and 251 times higher, respectively, on islands where humans have not introduced rats. Consequently, rat-free islands had substantially higher nitrogen stable isotope (δ15N) values in soils and shrubs, reflecting pelagic nutrient sources. These higher values of δ15N were also apparent in macroalgae, filter-feeding sponges, turf algae and fish on adjacent coral reefs. Herbivorous damselfish on reefs adjacent to the rat-free islands grew faster, and fish communities had higher biomass across trophic feeding groups, with 48% greater overall biomass. Rates of two critical ecosystem functions, grazing and bioerosion, were 3.2 and 3.8 times higher, respectively, adjacent to rat-free islands. Collectively, these results reveal how rat introductions disrupt nutrient flows among pelagic, island and coral reef ecosystems. Thus, rat eradication on oceanic islands should be a high conservation priority as it is likely to benefit terrestrial ecosystems and enhance coral reef productivity and functioning by restoring seabird-derived nutrient subsidies from large areas of ocean.Productivity of coral reefs is enhanced near islands with no invasive rats, as populations of seabirds, which transfer nitrogen from deeper areas of ocean to the nearshore waters via their guano, are much larger than on rat-infested islands.

中文翻译：

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海鸟在没有侵入性老鼠的情况下提高珊瑚礁的生产力和功能

生态系统之间的生物连通性可以提供有机物质和养分的主要运输，影响生态系统结构和生产力 1，但由于人类对自然流动的破坏，人们对其影响知之甚少。当海鸟数量充足时，在公海觅食的海鸟会将大量营养物质输送到岛屿上，从而提高岛屿动植物群的生产力3,4。尚不清楚这些营养物质是否会渗入海中，从而影响邻近珊瑚礁生态系统的生产力、结构和功能。在这里，我们通过在查戈斯群岛进行的一项罕见的自然实验来解决这个问题，其中一些岛屿有老鼠出没，而其他岛屿则没有老鼠。我们发现海鸟密度和氮沉积率分别高出 760 和 251 倍，在人类没有引入老鼠的岛屿上。因此，无鼠岛在土壤和灌木中具有更高的氮稳定同位素 (δ15N) 值，反映了远洋营养源。这些较高的 δ15N 值在大型藻类、滤食性海绵、草皮藻类和邻近珊瑚礁的鱼类中也很明显。与无鼠岛相邻的珊瑚礁上的食草雀鲷生长得更快，鱼类群落在营养饲养组中的生物量更高，总生物量增加了 48%。与无鼠岛相邻的两个关键生态系统功能，放牧和生物侵蚀的速率分别高出 3.2 和 3.8 倍。总的来说，这些结果揭示了老鼠的引入如何破坏远洋、岛屿和珊瑚礁生态系统之间的营养流动。因此，