ABSTRACT: Biotic interactions have critical effects on the structure of ecological communities, and the variation in the strength of these interactions over space and time contributes to biogeographic variation in communities. Predation shapes community composition in a variety of habitats, although there have been comparatively few experimental studies of these effects across latitudinal scales. We tested the impact of predator exclusion on the development of epifaunal communities across 3 sites (Florida [USA], Belize, and Panama) in seagrass habitats dominated by Thalassia testudinum using caged and uncaged settlement panels. We found that predators altered composition and slowed development of epifaunal communities. The nature and magnitude of these effects, however, were complex, site-dependent, and tightly coupled to community development. Fast-growing, soft-bodied species dominated space when predators were excluded, while more resistant calcifying species were dominant in communities exposed to predators. In Panama, non-native ascidians dominated communities in cages, while ascidians were consumed when exposed to predators, indicating the importance of biotic resistance at that site. Predators also reduced the abundance of associated small mobile fauna, and the positive correlation between mobile faunal abundances and sessile biomass in our study suggests a potential indirect effect of predator-mediated habitat modification. Overall, prey characteristics were important in explaining the site-specific effects of predators on communities, indicating that taxonomic resolution can influence the results of multi-regional studies examining the mechanisms affecting community structure.

中文翻译：

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捕食者对海草床表beds群落发育影响的空间变异

摘要：生物相互作用对生态群落的结构具有关键影响，而这些相互作用的强度随时间和空间的变化会导致群落的生物地理变异。捕食影响着各种栖息地的群落组成，尽管在横向范围内对这些影响的实验研究相对较少。我们测试捕食者排除对epifaunal社区的发展跨越3个站点（佛罗里达[美国]，伯利兹和巴拿马）由主导海草栖息地的影响Thalassia testudinum使用笼式和非笼式沉降板。我们发现掠食者改变了组成并减缓了表生动物群落的发展。但是，这些影响的性质和严重程度是复杂的，取决于地点的，并且与社区发展紧密相关。当捕食者被排除在外时，快速生长的柔和物种占主导地位，而更多的抗钙化物种在暴露于捕食者的社区中占主导地位。在巴拿马，非本地海生动物在笼养社区中占主导地位，而海生动物在被捕食者捕食时被消耗掉，这表明该地点对生物产生抗药性的重要性。捕食者还减少了相关的小型流动动物的数量，而且在我们的研究中，动植物种群数量与无柄生物量之间的正相关关系表明，捕食者介导的生境改变具有潜在的间接影响。总体而言，猎物的特性对于解释捕食者对社区的特定场所影响很重要，表明分类学解决方案可以影响研究影响社区结构的机制的多区域研究的结果。