The future of the wild oyster fishery in the northern Gulf of Mexico is largely uncertain due to changing environmental conditions and declining abundance of harvestable oysters. Specifically, rising temperatures can directly impact the physiological thresholds of the eastern oyster (Crassostrea virginica) at all life history stages and alter the narrow ecological niche this oyster occupies. The impact of rising temperatures is likely most pronounced during atmospheric heatwaves, defined as three or more days above the 90th percentile of daily maximum air temperatures, which have been shown to be increasing in frequency. Increasing exposure to high temperature extremes may contribute to and exacerbate an already declining oyster fishery. Critical to fishery health is recruitment i.e., the addition of new harvestable biomass, which is a dynamic process strongly driven by temperature. Here, we examine the relationship between heatwave characteristics and the prediction of poor oyster recruitment, measured as the abundance of post-larval oysters (e.g. spat) below the site-specific median density observed in historically productive oyster fisheries over 46-years (1976 – 2020) in Mobile Bay, Alabama and 21-years (1993 – 2014) in Apalachicola Bay, Florida. We acquired daily maximum air temperature measurements measured over 50 years (1970 – 2020) at weather monitoring stations adjacent to the bays to identify site specific annual heatwave events (maximum yearly air temperature, yearly and consecutive heatwave days, and number of annual heatwaves). Then, years with extreme heatwaves that exceeded the 75th percentile for the 50-year measurements were compared to years with non-extreme heatwave events. Years with extreme total heatwave days and extreme consecutive heatwave days were correlated with low post-larval oyster density. Across both bay systems, if consecutive heatwave days exceeded 11 days, then poor recruitment of oysters occurred 83 % of the time. Extreme heatwave duration as an indicator for poor recruitment has the potential to be a powerful tool for fishery managers to forecast recruitment and inform sustainable oyster harvest based on year-to-year variability in heatwave duration and long-term warming trends. Our findings illustrate how extreme temperatures can exacerbate multiple physiological and ecological stressors resulting in the loss of a keystone species for healthy and resilient coastal ecosystems.

中文翻译：

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热浪持续时间的延长对墨西哥湾牡蛎的可持续性构成威胁

由于环境条件的变化和可捕捞牡蛎数量的减少，墨西哥湾北部野生牡蛎渔业的未来在很大程度上不确定。具体来说，气温上升会直接影响东部牡蛎（Crassostrea virginica）在所有生命史阶段和年​​龄上该牡蛎所占据的狭窄生态位的生理阈值。气温上升的影响可能在大气热浪期间最为明显，大气热浪的定义是超过每日最高气温 90% 的三天或以上，而且这种频率已被证明在增加。越来越多地暴露在极端高温下可能会导致并加剧本已下降的牡蛎渔业。对渔业健康至关重要的是补充，即增加新的可收获生物量，这是一个受温度强烈驱动的动态过程。在这里，我们研究了热浪特征与牡蛎补充不良的预测之间的关系，牡蛎补充不良的预测是指幼体牡蛎（例如卵）的丰度低于 46 年（1976 年至 2020 年）历史上高产牡蛎渔业中观察到的特定地点中位密度。 ）在阿拉巴马州莫比尔湾，在佛罗里达州阿巴拉契科拉湾工作了 21 年（1993 年至 2014 年）。我们获取了 50 年来（1970 年至 2020 年）在海湾附近的气象监测站测量的每日最高气温测量值，以确定特定地点的年度热浪事件（年度最高气温、年度和连续热浪天数以及年度热浪次数）。然后，将极端热浪超过 50 年测量值第 75 个百分位数的年份与非极端热浪事件的年份进行比较。极端总热浪日数和极端连续热浪日数的年份与低幼体牡蛎密度相关。在这两个海湾系统中，如果连续热浪天数超过 11 天，则 83% 的情况会出现牡蛎补充不良的情况。极端热浪持续时间作为补充不良的指标，有可能成为渔业管理者根据热浪持续时间和长期变暖趋势的逐年变化预测补充并为可持续牡蛎收获提供信息的有力工具。我们的研究结果表明，极端温度如何加剧多种生理和生态压力，导致健康和有弹性的沿海生态系统的关键物种丧失。