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Allochthonous aquatic subsidies alleviate predation pressure in terrestrial ecosystems
Ecology ( IF 4.4 ) Pub Date : 2020-05-20 , DOI: 10.1002/ecy.3074 Fátima C Recalde 1, 2 , Crasso P B Breviglieri 3 , Gustavo Q Romero 3
Ecology ( IF 4.4 ) Pub Date : 2020-05-20 , DOI: 10.1002/ecy.3074 Fátima C Recalde 1, 2 , Crasso P B Breviglieri 3 , Gustavo Q Romero 3
Affiliation
The input of external energy and matter in recipient ecosystems can act as a bottom-up force that subsidizes consumers, with subsequent cascading effects throughout the food web. Depending on the amount of input, dietary preference and the strength of trophic links, allochthonous resources generally play a stabilizing role on food webs. In this study, we investigated the stabilizing role of allochthonous aquatic resources on intraguild predation (IGP) and their consequences on shared prey in a terrestrial ecosystem. To this end, we manipulated the input of emergent aquatic insects (the allochthonous resources) from streams to land, and predation pressure by bats and birds (the top predators), in a multi-trophic food web using an orthogonal exclusion experiment. Using stable isotope metrics, we found that bats, birds, and spiders (the mesopredators), were highly subsidized by emergent aquatic insects. Moreover, among terrestrial prey, top predators fed more on spiders than insects. As predicted, spiders were strongly affected by the presence of top predators when allochthonous resources were excluded. Consequently, in this scenario terrestrial insects were two times more abundant. Since spiders showed a higher preference for consuming aquatic resources, we suggest that non-consumptive effects of spiders upon terrestrial insects could be mediating the strong response of those shared prey. We demonstrate that the input of allochthonous aquatic resources can play a fundamental role in stabilizing terrestrial trophic interactions and trophic cascades in riparian zones via decreasing predation pressure.
更新日期：2020-05-20
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