The role of habitat‐forming species in promoting biodiversity is widely acknowledged to vary across environmental gradients according to the extent to which they modify resources and environmental conditions. Population‐ and individual‐level traits of habitat‐forming species that influence species interactions may vary across gradients, but the importance of this indirect effect of environmental context is seldom considered. Here, we conducted surveys and field experiments to partition the effects of wave exposure on habitat‐provisioning for invertebrates by oysters into direct and indirect effects, arising from morphological variation of the oysters. A survey of nine sites with varying degrees of wave exposure in Port Jackson, Australia revealed a decline in oyster densities and surface area as wave energy increased. Correlated to declining oyster surface area was a decrease in the richness and abundance of associated invertebrates. By contrast, taxon diversity increased with increasing wave energy. Experimental deployments of oysters at high and low wave energy sites confirmed that variations in oyster morphology was a phenotypically plastic response to environmental conditions. Oyster recruitment was also lower at high as compared to low wave energy sites, further contributing to the variation in oyster habitat among sites. A colonisation experiment in which exposed and sheltered morphologies of oysters were deployed under high and low wave energy conditions in a fully orthogonal design found that invertebrate communities were influenced by both the wave energy of sites and by habitat structure. Our study suggests that in some instances the indirect effects of environment on habitat availability, arising from changes in habitat‐forming species density and morphology, may be as, or even more, important than the direct effects. Understanding how traits of habitat‐forming species respond to environmental conditions, and how intraspecific trait‐variation cascades to influence associated communities is critical to predicting when and where positive species interactions will be greatest.

中文翻译：

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波能通过塑造形成栖息地的物种的种内特征来改变生物多样性

人们普遍认为，形成栖息地的物种在促进生物多样性方面的作用根据其改变资源和环境条件的程度而在环境梯度上各不相同。影响物种相互作用的生境形成物种的种群和个体水平特征可能会随梯度的变化而变化，但是很少考虑这种环境环境间接影响的重要性。在这里，我们进行了调查和田间实验，将牡蛎无脊椎动物的海浪暴露对栖息地供应的影响分为由牡蛎形态变化引起的直接和间接影响。对澳大利亚杰克逊港9个不同程度的波曝露地点进行的一项调查显示，随着波能的增加，牡蛎密度和表面积下降。与牡蛎表面积下降有关的是相关无脊椎动物的丰富度和丰度下降。相比之下，分类单元多样性随波能的增加而增加。在高和低波能量位点上的牡蛎实验性部署证实，牡蛎形态的变化是对环境条件的表型塑性响应。与低波能量站点相比，牡蛎的募集量也较高，这进一步加剧了站点之间牡蛎栖息地的变化。在完全正交的设计中，在高和低波能条件下部署牡蛎裸露和庇护形态的定殖实验发现，无脊椎动物群落受场所波能和栖息地结构的影响。我们的研究表明，在某些情况下，由栖息地形成物种密度和形态变化引起的环境对栖息地可利用性的间接影响可能比直接影响重要，甚至更为重要。了解生境形成物种的性状如何对环境条件作出反应，以及种内性状变异如何级联影响相关社区，对于预测何时和何处物种正向相互作用将是最大的至关重要。