Data from: Differential responses to ocean acidification between populations of Balanophyllia elegans corals from high and low upwelling environments

Ocean acidification (OA), the global decrease in surface water pH from
absorption of anthropogenic CO2, may put many marine taxa at risk.
However, populations that experience extreme localized conditions, and are
adapted to these conditions predicted in the global ocean in 2100, may be
more tolerant to future OA. By identifying locally adapted populations,
researchers can examine the mechanisms used to cope with decreasing pH.
One oceanographic process that influences pH, is wind driven upwelling.
Here we compare two Californian populations of the coral Balanophyllia
elegans from distinct upwelling regimes, and test their physiological and
transcriptomic responses to experimental seawater acidification. We
measured respiration rates, protein and lipid content, and gene expression
in corals from both populations exposed to pH levels of 7.8 and 7.4 for 29
days. Corals from the population that experiences lower pH due to high
upwelling, maintained the same respiration rate throughout the exposure.
In contrast, corals from the low upwelling site had reduced respiration
rates, protein content, and lipid-class content at low pH exposure,
suggesting they have depleted their energy reserves. Using RNA-Seq, we
found that corals from the high upwelling site upregulated genes involved
in calcium ion binding and ion transport, most likely related to pH
homeostasis and calcification. In contrast, corals from the low upwelling
site downregulated stress response genes at low pH exposure. Divergent
population responses to low pH observed in B. elegans highlight the
importance of multi-population studies for predicting a species’ response
to future OA.

海洋酸化（Ocean Acidification, OA）指因吸收人为源二氧化碳而导致的全球表层海水pH值下降，这一过程可能使诸多海洋类群面临生存风险。然而，那些长期处于极端局地环境、且已适应2100年全球海洋预估环境的种群，对未来海洋酸化或许具备更强的耐受能力。通过甄别本地适应型种群，研究者可深入解析生物应对pH值下降的内在机制。其中一项影响海水pH的海洋学过程为风力驱动上升流。本研究选取来自加利福尼亚州、处于不同上升流环境下的优雅角杯珊瑚（Balanophyllia elegans）两种群，对比二者在实验性海水酸化条件下的生理与转录组响应。我们将两种群的珊瑚分别置于pH7.8与pH7.4的环境中暴露29天，随后测定其呼吸速率、蛋白质与脂质含量以及基因表达水平。来自高上升流区域（该区域海水pH本底更低）的珊瑚，在整个暴露实验期间呼吸速率保持稳定。与之相反，来自低上升流区域的珊瑚在低pH暴露条件下，其呼吸速率、蛋白质含量与脂质组分含量均出现下降，提示其能量储备已被消耗殆尽。通过RNA-Seq（RNA测序），我们发现高上升流区域的珊瑚会上调与钙离子结合、离子转运相关的基因，这类基因大概率与pH稳态及钙化过程相关。与之相反，低上升流区域的珊瑚在低pH暴露条件下会下调应激反应相关基因。本研究中优雅角杯珊瑚（Balanophyllia elegans）种群对低pH的差异化响应，凸显了多种群研究在预测物种对未来海洋酸化响应中的重要意义。