Reverberating effects of resource exchanges in stream–riparian food webs
Reverberating effects of resource exchanges in stream–riparian food webs
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DOI：
10.1007/s00442-019-04574-y
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发表时间：
2019-12
期刊：
影响因子：
2.7
通讯作者：
S. Collins;C. Baxter;Amy M. Marcarelli;L. Felicetti;Scott T. Florin;M. Wipfli;G. Servheen
中科院分区：
文献类型：
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作者：
S. Collins;C. Baxter;Amy M. Marcarelli;L. Felicetti;Scott T. Florin;M. Wipfli;G. Servheen
物质或生物体跨越生态边界的通量，通常被称为“资源补贴”，直接影响到受援国的食物网。很少有研究涉及一个生态系统中的这种直接反应如何反过来影响物质或生物体到其他生境的通量，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，我们评估了一种假设，即随着响应跨越生态边界的分散，海洋来源补贴的投入会导致溪流和河岸生态系统之间复杂的资源交换（即投入、产出和反馈）。此外，我们通过对比鲑鱼尸体和颗粒化处理，评估了资源补贴的物理性质如何介导复杂反应。我们发现，鲑鱼的尸体通过直接补贴多种水生和陆生生物（如底栖昆虫幼虫、鱼类和陆生苍蝇）来改变河流-河岸的食物网。这种反应进一步沿着间接途径影响食物网，其中一些途径跨越陆地和水（例如，补贴鱼类减少了水生昆虫的出现，对蜘蛛和蝙蝠产生了影响）。当尸体被移到河岸栖息地时，补贴介导的反馈就表现出来了，在那里它们被腐肉蝇殖民，其中一些落入溪流，成为鱼类的另一种猎物补贴。由于鲑鱼补贴的影响通过河流-河岸食物网传播，消费者反应的迹象并不总是积极的，似乎是由营养相互作用的结果决定的，例如，一个生态系统内的局部营养相互作用介导了生物向其他生态系统的出口。
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.