Hawai'i Institute of Marine Biology, School of Ocean and Earth Science and Technology, University of Hawai'i, Kāne'ohe, HI, USA.
Department of Earth and Environmental Sciences, Macquarie University - Sydney, Sydney, NSW, Australia.
Glob Chang Biol. 2020 Feb;26(2):557-567. doi: 10.1111/gcb.14911. Epub 2019 Dec 14.
Rapid intensification of environmental disturbances has sparked widespread decline and compositional shifts in foundation species in ecosystems worldwide. Now, an emergent challenge is to understand the consequences of shifts and losses in such habitat-forming species for associated communities and ecosystem processes. Recently, consecutive coral bleaching events shifted the morphological makeup of habitat-forming coral assemblages on the Great Barrier Reef (GBR). Considering the disparity of coral morphological growth forms in shelter provision for reef fishes, we investigated how shifts in the morphological structure of coral assemblages affect the abundance of juvenile and adult reef fishes. We used a temporal dataset from shallow reefs in the northern GBR to estimate coral convexity (a fine-scale quantitative morphological trait) and two widely used coral habitat descriptors (coral cover and reef rugosity) for disentangling the effects of coral morphology on reef fish assemblages. Changes in coral convexity, rather than live coral cover or reef rugosity, disproportionately affected juvenile reef fishes when compared to adults, and explained more than 20% of juvenile decline. The magnitude of this effect varied by fish body size with juveniles of small-bodied species showing higher vulnerability to changes in coral morphology. Our findings suggest that continued large-scale shifts in the relative abundance of morphological groups within coral assemblages are likely to affect population replenishment and dynamics of future reef fish communities. The different responses of juvenile and adult fishes according to habitat descriptors indicate that focusing on coarse-scale metrics alone may mask fine-scale ecological responses that are key to understand ecosystem functioning and resilience. Nonetheless, quantifying coral morphological traits may contribute to forecasting the structure of reef fish communities on novel reef ecosystems shaped by climate change.
环境干扰的迅速加剧，在全球范围内引发了基础物种的广泛衰退和组成变化。现在，一个新出现的挑战是要了解这些栖息地形成物种的转移和丧失对相关群落和生态系统过程的后果。最近，连续的珊瑚白化事件改变了大堡礁（GBR）上形成栖息地的珊瑚组合的形态结构。考虑到珊瑚形态生长形式在为珊瑚礁鱼类提供庇护方面的差异，我们研究了珊瑚组合形态结构的变化如何影响幼年和成年珊瑚礁鱼类的丰度。我们使用了来自大堡礁北部浅礁的时间数据集来估计珊瑚的凸度（一种精细的定量形态特征）和两个广泛使用的珊瑚栖息地描述符（珊瑚覆盖率和珊瑚礁粗糙度），以区分珊瑚形态对珊瑚礁鱼类组合的影响。与成年鱼类相比，珊瑚凸度的变化（而不是活珊瑚覆盖率或珊瑚礁粗糙度）对幼年鱼类的影响不成比例，并且解释了 20%以上的幼年鱼类减少。这种影响的大小因鱼类体型而异，体型较小的物种的幼鱼对珊瑚形态变化的脆弱性更高。我们的研究结果表明，珊瑚组合中形态群体相对丰度的持续大规模变化可能会影响未来珊瑚礁鱼类群落的种群补充和动态。根据栖息地描述符，幼年鱼和成年鱼的不同反应表明，仅关注粗尺度指标可能掩盖对理解生态系统功能和弹性至关重要的细尺度生态反应。尽管如此，量化珊瑚形态特征可能有助于预测气候变化塑造的新型珊瑚礁生态系统中珊瑚礁鱼类群落的结构。
