Biotic interactions perform an important role in structuring freshwater communities; however, these are rarely considered during stream restoration. Degraded stream communities are often dominated by organisms with shell or case protections, such as snails, which are less vulnerable to predation than desired organisms, such as mayflies. Unprotected organisms may be preferentially eaten, limiting biotic restoration success after the physical restoration of degraded stream communities. We investigated whether restoration success depended on differences in vulnerability to predation by testing whether consumption-based interaction strengths (IS) between vulnerable colonizing Deleatidium spp. mayflies and upland bullies (Gobiomorphus breviceps) changed with different densities of protected Potamopyrgus antipodarum snails and whether snails affected Deleatidium behavior. Deleatidium and fish IS were stronger with fewer Deleatidium present, a destabilizing effect on vulnerable prey populations, and less total prey biomass was consumed with higher densities of protected relative to vulnerable prey, potentially having long-term negative effects on predators. Furthermore, mayflies appeared less on surfaces with high snail densities, potentially due to altered resource use. The combination of these biotic interactions could form a barrier to successful biotic restoration by preventing colonization of desired vulnerable prey, through priority effects within the established community. Therefore, considering biotic interactions in stream restoration is important to overcome biotic restoration barriers.

中文翻译：

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生物相互作用在河流恢复中的潜在作用

生物相互作用在构建淡水群落方面发挥着重要作用；然而，在河流恢复过程中很少考虑这些。退化的河流群落通常由具有外壳或外壳保护的生物主导，例如蜗牛，与所需的生物（例如蜉蝣）相比，它们更不容易受到捕食。未受保护的生物可能会被优先食用，从而限制了退化河流群落物理恢复后生物恢复的成功。我们通过测试脆弱的定植Deleatidium spp之间基于消费的相互作用强度 (IS) 是否取决于捕食脆弱性的差异，研究了恢复成功是否取决于捕食脆弱性的差异。蜉蝣和高地恶霸（Gobiomorphus breviceps）随着受保护的Potamopyrgus antipodarum蜗牛的不同密度以及蜗牛是否影响Deleatidium行为而变化。Deleatidium和鱼的 IS 更强，Deleatidium较少目前，对脆弱的猎物种群产生不稳定影响，并且相对于脆弱的猎物，受保护的猎物密度更高，消耗的总猎物生物量较少，可能对捕食者产生长期的负面影响。此外，蜉蝣在蜗牛密度高的表面上出现的次数较少，这可能是由于资源使用的改变。这些生物相互作用的结合可以通过已建立社区内的优先效应阻止所需脆弱猎物的定殖，从而形成成功恢复生物的障碍。因此，考虑河流恢复中的生物相互作用对于克服生物恢复障碍很重要。