Fine-scale variability in coral bleaching and mortality during a marine heatwave-猫眼课题宝

DOI：

10.3389/fmars.2023.1108365

发表时间：

2022-11

期刊：

bioRxiv

影响因子：

通讯作者：

中科院分区：

其他

文献类型：

作者：

S. Yadav;Ty N. F. Roach;M. McWilliam;C. Caruso;M. R. de Souza;Catherine Foley;Corinne Allen;Jenna Dilworth;Joel Huckeba;E. Santoro;Renee Wold;Jacqueline Simpson;S. Miller;Joshua R. Hancock;C. Drury;J. Madin

珊瑚漂白和死亡率可在地方尺度上表现出显著的空间和分类异质性，突出了了解热应激的细尺度驱动因素和影响的必要性。在这项研究中，我们使用运动结构摄影测量来跟踪2019年海洋热浪期间夏威夷KāNe‘ohe湾珊瑚白化、死亡率和群落组成的变化。在白化事件持续的3周(8-12月)和一年后，我们每3周调查30个浅礁斑块，总共产生了210张大面积、高分辨率的照片，使我们能够随着时间的推移跟踪数以千计的珊瑚群落的命运。我们还测量了每个地点的环境变量，如温度、沉积、深度和波速，并从数字海拔模型中提取了栖息地复杂性的估计(粗糙度R和分维D)，以更好地了解它们对漂白和死亡模式的影响。我们发现，在此期间，高达80%的珊瑚经历了中度到重度的白化，其中白化的高峰期出现在10月份，此时热应激(DHW)达到最大值。随着漂白程度的下降，死亡率继续累积，导致较热敏感物种的死亡率大幅下降(Pocillopora盖度减少77%)，耐热物种的死亡率中等下降(扁平孔菌和头状单孢菌分别为19%和23%)。随着活珊瑚数量的减少，整个调查地点的藻类覆盖率迅速增加。白化的空间差异与栖息地的复杂性和珊瑚物种组成显著相关，以Pocillopora为主的珊瑚礁经历了最严重的白化。死亡率还受物种组成、分维和热应激的地点水平差异的影响。我们的结果表明，漂白影响的空间异质性是由环境变化、生境复杂性和群落组成的差异共同驱动的。

Coral bleaching and mortality can show significant spatial and taxonomic heterogeneity at local scales, highlighting the need to understand the fine-scale drivers and impacts of thermal stress. In this study, we used structure-from-motion photogrammetry to track coral bleaching, mortality, and changes in community composition during the 2019 marine heatwave in Kāne‘ohe Bay, Hawai‘i. We surveyed 30 shallow reef patches every 3 weeks for the duration of the bleaching event (August-December) and one year after, resulting in a total of 210 large-area, high-resolution photomosaics that enabled us to follow the fate of thousands of coral colonies through time. We also measured environmental variables such as temperature, sedimentation, depth, and wave velocity at each of these sites, and extracted estimates of habitat complexity (rugosity R and fractal dimension D) from digital elevation models to better understand their effects on patterns of bleaching and mortality. We found that up to 80% of corals experienced moderate to severe bleaching in this period, with peak bleaching occurring in October when heat stress (DHW) reached its maximum. Mortality continued to accumulate as bleaching levels dropped, driving large declines in more heat-susceptible species (77% loss of Pocillopora cover) and moderate declines in heat-tolerant species (19% and 23% for Porites compressa and Montipora capitata, respectively). Declines in live coral were accompanied by a rapid increase in algal cover across the survey sites. Spatial differences in bleaching were significantly linked to habitat complexity and coral species composition, with reefs that were dominated by Pocillopora experiencing the most severe bleaching. Mortality was also influenced by species composition, fractal dimension, and site-level differences in thermal stress. Our results show that spatial heterogeneity in the impacts of bleaching are driven by a mix of environmental variation, habitat complexity, and differences in assemblage composition.

Fine-scale variability in coral bleaching and mortality during a marine heatwave

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