Fluxes of materials or organisms across ecological boundaries, often termed "resource subsidies," directly affect recipient food webs. Few studies have addressed how such direct responses in one ecosystem may, in turn, influence the fluxes of materials or organisms to other habitats or the potential for feedback relationships to occur among ecosystems. As part of a large-scale, multi-year experiment, we evaluated the hypothesis that the input of a marine-derived subsidy results in a complex array of resource exchanges (i.e., inputs, outputs, feedbacks) between stream and riparian ecosystems as responses disperse across ecological boundaries. Moreover, we evaluated how the physical properties of resource subsidies mediated complex responses by contrasting carcasses with a pelletized salmon treatment. We found that salmon carcasses altered stream-riparian food webs by directly subsidizing multiple aquatic and terrestrial organisms (e.g., benthic insect larvae, fishes, and terrestrial flies). Such responses further influenced food webs along indirect pathways, some of which spanned land and water (e.g., subsidized fishes reduced aquatic insect emergence, with consequences for spiders and bats). Subsidy-mediated feedbacks manifested when carcasses were removed to riparian habitats where they were colonized by carrion flies, some of which fell into the stream and acted as another prey subsidy for fishes. As the effects of salmon subsidies propagated through the stream-riparian food web, the sign of consumer responses was not always positive and appeared to be determined by the outcome of trophic interactions, such that localized trophic interactions within one ecosystem mediated the export of organisms to others.

中文翻译：

---

河岸食物网中资源交换的反响作用。

跨生态边界的物质或生物体的流动，通常被称为“资源补贴”，直接影响着受援者的食物网。很少有研究探讨一个生态系统中的这种直接反应可能反过来又如何影响物质或生物向其他生境的流动或生态系统之间发生反馈关系的可能性。作为一项大规模，多年实验的一部分，我们评估了以下假设：海洋补贴的输入导致河流和河岸生态系统之间的资源交换（即输入，输出，反馈）复杂阵列，作为回应跨越生态边界。此外，我们通过将car体与鲑鱼颗粒处理进行对比，评估了资源补贴的物理性质如何介导复杂的反应。我们发现，鲑鱼尸体通过直接补贴多种水生和陆地生物（例如底栖昆虫幼虫，鱼类和陆地蝇）来改变河岸食物网。这种反应进一步影响了间接途径的食物网，其中一些跨越土地和水域（例如，受补贴的鱼类减少了水生昆虫的出现，对蜘蛛和蝙蝠产生了影响）。当尸体被移至河岸栖息地并被腐肉蝇定殖时，便出现了补贴介导的反馈，其中一些腐烂蝇落入溪流，并作为鱼类的另一种猎物补贴。随着鲑鱼补贴的影响通过河岸食物网传播，消费者反应的信号并不总是积极的，似乎由营养相互作用的结果决定，