Habitat area and fragmentation are recognised as important factors that influence population size, community structure and extinction risk. Abundance and species richness universally increase with habitat area. However, the effects of different aspects of habitat fragmentation, including variation in patch size, number and isolation are often not distinguished from each other or the overall effects of habitat amount. Here we experimentally tested predictions concerning the effects of isolation on abundance, species richness and community structure of coral reef fishes colonising patch reefs by constructing clusters of patches of the same number and size, but manipulating reef spacing. Hexagonal clusters of 7 experimental patch reefs (6 edge and 1 central) with 3 levels of isolation (1 m, 5 m, and 15 m spacing) were established at Kavieng, Papua New Guinea and colonisation was recorded after 6 weeks in 2014. We also deployed video cameras to test whether isolation affected the activity of transient predatory fishes. As predicted, isolation had a positive effect on both mean abundance and species richness at both the cluster and patch scale. The cumulative abundance and species richness exhibited linear increases in relation to habitat area within clusters (from 1 to 7 patch reefs), but the slope increased with the degree of isolation. There was some evidence that transient predators remained longer and were more successful when patches were close together, which may explain the lower abundance and richness of juvenile fish assemblages on more aggregated patch reefs. This study demonstrates that while habitat amount is fundamentally important, isolation has significant effects that will need to be distinguished from other aspects of fragmentation when examining the processes structuring reef fish communities.

中文翻译：

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隔离促进了招募到珊瑚礁斑块的鱼类的丰度和物种丰富度

栖息地面积和破碎化被认为是影响种群规模、群落结构和灭绝风险的重要因素。丰富度和物种丰富度普遍随着栖息地面积的增加而增加。然而，栖息地破碎化的不同方面的影响，包括斑块大小、数量和隔离的变化，通常无法相互区分或栖息地数量的整体影响。在这里，我们通过构建相同数量和大小的斑块簇，但操纵珊瑚礁间距，通过实验测试了关于隔离对定居斑块礁的珊瑚礁鱼类的丰度、物种丰富度和群落结构影响的预测。在 Kavieng 建立了具有 3 个隔离级别（1 m、5 m 和 15 m 间距）的 7 个实验斑礁（6 个边缘和 1 个中心）的六边形集群，2014 年 6 周后记录了巴布亚新几内亚和殖民化。我们还部署了摄像机来测试隔离是否影响了短暂的掠食性鱼类的活动。正如预测的那样，隔离对集群和斑块规模的平均丰度和物种丰富度都有积极影响。累积丰度和物种丰富度与集群内的栖息地面积（从 1 到 7 个斑块礁）呈线性增加，但坡度随着隔离程度的增加而增加。有一些证据表明，当斑块靠在一起时，短暂的捕食者会保持更长的时间并且更成功，这可能解释了在更聚集的斑块礁石上幼鱼组合的丰度和丰富度较低。这项研究表明，虽然栖息地数量从根本上来说很重要，