University of Guam Marine Laboratory, UoG Station, Mangilao, GU, 96923, USA.
Institute for Global Ecology, Florida Institute of Technology, 150 West University Blvd, Melbourne, Fl, 32901, USA.
Sci Rep. 2023 Jun 8;13(1):9338. doi: 10.1038/s41598-023-36355-2.
Thermal-stress events on coral reefs lead to coral bleaching, mortality, and changes in species composition. The coral reefs of Yap, in the Federated States of Micronesia, however, remained largely unaffected by major thermal-stress events until 2020, when temperatures were elevated for three months. Twenty-nine study sites were examined around Yap to determine geographical and taxonomic patterns of coral abundance, bleaching susceptibility, and environmental predictors of bleaching susceptibility. Island-wide, 21% (± 14%) of the coral cover was bleached in 2020. Although inner reefs had a greater proportion of thermally-tolerant Porites corals, the prevalence of bleaching was consistently lower on inner reefs (10%) than on outer reefs (31%) for all coral taxa. Corals on both inner and outer reefs along the southwestern coast exhibited the lowest prevalence of coral bleaching and had consistently elevated chlorophyll-a concentrations. More broadly, we revealed a negative relationship between bleaching prevalence and (moderate) chlorophyll-a concentrations that may have facilitated resistance to thermal stress by reducing irradiance and providing a heterotrophic energy source to benefit some corals exposed to autotrophic stress. Southwestern reefs also supported a high but declining fish biomass, making these bleaching-resistant and productive reefs a potential climate-change refuge and a prime target for conservation.
热应激事件导致珊瑚白化、死亡和物种组成变化。然而，密克罗尼西亚联邦的雅浦岛的珊瑚礁在 2020 年之前基本上没有受到重大热应激事件的影响，当时温度升高了三个月。在雅浦岛周围检查了 29 个研究地点，以确定珊瑚丰度、白化易感性的地理和分类模式，以及白化易感性的环境预测因子。全岛范围内，2020 年有 21%（±14%）的珊瑚覆盖物白化。尽管内礁有更多的耐热多孔螅珊瑚，但所有珊瑚类群的内礁（10%）的白化流行率始终低于外礁（31%）。西南海岸的内礁和外礁的珊瑚白化率最低，叶绿素 a 浓度始终较高。更广泛地说，我们发现白化流行率与（中等）叶绿素 a 浓度之间存在负相关关系，这可能通过减少光照并为暴露于自养胁迫的一些珊瑚提供异养能量源，从而有助于抵抗热应激。西南礁还支持着较高但正在下降的鱼类生物量，使这些抗白化和多产的礁成为潜在的气候变化避难所，也是保护的主要目标。
