Data from: Long-lived groupers require structurally stable reefs in the face of repeated climate change disturbances

Benthic recovery from climate-related disturbances does not always warrant a commensurate functional recovery for reef-associated fish communities. Here, we examine the distribution of benthic groupers (family Serranidae) in coral reef communities from the Lakshadweep archipelago (Arabian Sea) in response to structural complexity and long-term habitat stability. These coral reefs that have been subject to two major El Niño Southern Oscillation-related coral bleaching events in the last decades (1998 and 2010). First, we employ a long-term (12-yr) benthic-monitoring dataset to track habitat structural stability at twelve reef sites in the archipelago. Structural stability of reefs was strongly driven by exposure to monsoon storms and depth, which made deeper and more sheltered reefs on the eastern aspect more stable than the more exposed (western) and shallower reefs. We surveyed groupers (species richness, abundance, biomass) in 60 sites across the entire archipelago, representing both exposures and depths. Sites were selected along a gradient of structural complexity from very low to high. Grouper biomass appeared to vary with habitat stability with significant differences between depth and exposure; sheltered deep reefs had a higher grouper biomass than either sheltered shallow or exposed (deep and shallow) reefs. Species richness and abundance showed similar (though not significant) trends. More interestingly, average grouper biomass increased exponentially with structural complexity, but only at the sheltered deep (high stability) sites, despite the availability of recovered structure at exposed deep and shallow sites (lower-stability sites). This trend was especially pronounced for long-lived groupers (life span >10 yrs). These results suggest that long-lived groupers may prefer temporally stable reefs, independent of the local availability of habitat structure. In reefs subject to repeated disturbances, the presence of structurally stable reefs may be critical as refuges for functionally important, long-lived species like groupers.

经历气候相关扰动后的底栖生物恢复，并不总能保证礁栖鱼类群落实现相应的功能恢复。本研究聚焦阿拉伯海拉克沙群岛珊瑚礁群落中的底栖石斑鱼（鮨科Serranidae）分布情况，探究其与栖息地结构复杂度及长期生境稳定性的关联。该海域的珊瑚礁在过去数十年间曾遭受两次与厄尔尼诺-南方涛动（El Niño Southern Oscillation）相关的大规模珊瑚白化事件（分别发生于1998年与2010年）。首先，本研究利用为期12年的长期底栖监测数据集，追踪该群岛12个礁区的生境结构稳定性。礁区的结构稳定性主要受季风风暴暴露程度与水深驱动：相较于暴露度更高的西侧及浅水区礁体，东侧受庇护的深水礁体稳定性更强。研究团队在全群岛范围内的60个样点开展石斑鱼调查，涵盖不同暴露度与水深梯度的区域；样点的选取覆盖了结构复杂度从极低到极高的完整梯度。石斑鱼生物量似乎随生境稳定性发生变化，且在水深与暴露度上存在显著差异：受庇护的深水礁体的石斑鱼生物量，显著高于受庇护的浅水区礁体以及暴露度较高的深、浅水区礁体。物种丰富度与丰度则呈现出相似（虽未达到显著水平）的变化趋势。更值得关注的是，仅在受庇护的深水高稳定性样点中，石斑鱼平均生物量随结构复杂度呈指数增长；即便暴露度较高的深、浅水区样点已恢复了礁体结构（稳定性较低），该趋势仍未出现。对于寿命超过10年的长寿命石斑鱼而言，这一趋势尤为显著。上述结果表明，长寿命石斑鱼可能更偏好长期稳定的礁体生境，而非依赖当地当下可获取的栖息地结构。在经历反复扰动的珊瑚礁生态系统中，具备结构稳定性的礁体可能作为石斑鱼这类具有重要生态功能的长寿命物种的庇护所，其存在至关重要。