Data_Sheet_1_Synergistic Effects of Thermal Stress and Estuarine Discharge on Transcriptomic Variation of Montastraea cavernosa Corals in Southeast Florida.pdf

Coral reefs at the northern extent of Florida’s coral reef tract are exposed to many localized anthropogenic influences including controlled freshwater discharges, runoff, upwelling, and seasonal environmental variability. To better understand coral responses to sublethal stressors in nearshore environments, we conducted complementary experiments to assess the impacts of estuarine runoff and temperature stress on local populations of the scleractinian coral species, Montastraea cavernosa, using Tag-Seq global gene expression profiling. In an in situ time series experiment, fate-tracked colonies were sampled during periods of relatively low and high estuarine discharge over 4 years to investigate temporal trends in transcriptional patterns and to identify if coral stress indicators were regulated through time. There was significant transcriptomic variation through time, but patterns did not appear to be attributed to distance from nearby estuarine tidal flux. In an ex situ factorial experiment, clonal replicates of coral genotypes were exposed to temperature (25°C and 30°C) and water (offshore and estuarine discharge, representing typical oceanic conditions and episodic discharge conditions, respectively) treatments to quantify the potential individual and synergistic effects of sublethal stress on coral and algal gene expression. Comparative analyses suggested that corals and their algal symbionts were more responsive to thermal stress than to estuarine discharge, although there was evidence of a synergistic relationship between the two stressors. Strong genotype effects also demonstrated that transcriptomic responses to thermal stress were largely based on coral genotype, indicating the potential for stress resilience among certain members of coral populations from southeast Florida.

佛罗里达珊瑚礁带最北端的珊瑚礁群落，面临多种局地人为活动与自然环境胁迫，包括受控淡水排放、地表径流、上升流及季节性环境波动。为深入解析珊瑚对近岸环境中亚致死胁迫因子的响应机制，本研究采用Tag-Seq全局基因表达谱分析技术，针对本地石珊瑚（scleractinian coral）物种Montastraea cavernosa开展配套实验，以评估河口径流与温度胁迫对其种群的影响。在原位（in situ）时间序列实验中，研究团队于4年周期内的河口低排放与高排放时段分别采集标记追踪的珊瑚群体样本，旨在解析转录模式的时间动态趋势，并探究珊瑚胁迫指示因子是否随时间发生调控变化。研究发现，转录组特征随时间存在显著差异，但该差异模式似乎与距附近河口潮汐通量的距离无关。在异位（ex situ）析因实验中，研究团队将珊瑚基因型的克隆复株分别置于温度（25℃与30℃）与水体（近海与河口排放，分别代表典型海洋环境与间歇性排放环境）处理组中，以量化亚致死胁迫对珊瑚及其藻类共生体基因表达的潜在单独效应与协同效应。比较分析结果显示，相较于河口径流胁迫，珊瑚及其藻类共生体对热胁迫的响应更为强烈，但同时也存在两种胁迫间存在协同关系的证据。显著的基因型效应同时表明，珊瑚对热胁迫的转录组响应主要由珊瑚基因型决定，这提示佛罗里达东南部珊瑚种群中部分个体具备胁迫抗性潜力。