Physiological plasticity and local adaptation to elevated pCO2 in calcareous algae: an ontogenetic and geographic approach

To project how ocean acidification will impact biological communities in the future, it is critical to understand the potential for local adaptation and the physiological plasticity of marine organisms throughout their entire life cycle, as some stages may be more vulnerable than others. Coralline algae are ecosystem engineers that play significant functional roles in oceans worldwide, and are considered vulnerable to ocean acidification. Using different stages of coralline algae, we tested the hypothesis that populations living in environments with higher environmental variability and exposed to higher levels of pCO2 would be less affected by high pCO2 than populations from a more stable environment experiencing lower levels of pCO2. Our results show that spores are less sensitive to elevated pCO2 than adults. Spore growth and mortality were not affected by pCO2 level, however elevated pCO2 negatively impacted the physiology and growth rates of adults, with stronger effects in populations that experienced both lower levels of pCO2 and lower variability in carbonate chemistry, suggesting local adaptation. Differences in physiological plasticity and the potential for adaptation could have important implications for the ecological and evolutionary responses of coralline algae to future environmental changes.

为预测未来海洋酸化对海洋生物群落的影响，阐明海洋生物在整个生命周期中的本地适应潜力与生理可塑性至关重要——因其不同发育阶段的耐受程度存在差异。珊瑚藻（Coralline algae）是全球海洋中发挥关键生态功能的生态系统工程师，且被认为对海洋酸化较为敏感。本研究以不同发育阶段的珊瑚藻为材料，验证了如下假说：相较于栖息于pCO₂水平更低、碳酸盐化学环境更稳定的种群，长期暴露于高环境波动与高pCO₂环境的种群，受高pCO₂胁迫的影响更弱。研究结果显示，珊瑚藻孢子对升高的pCO₂的敏感性低于成体：孢子的生长与死亡率不受pCO₂水平影响，但高pCO₂会对成体的生理状态与生长速率产生负面影响，且在pCO₂水平更低、碳酸盐化学波动更小的种群中，这种负面影响更为显著，这提示珊瑚藻存在本地适应现象。珊瑚藻的生理可塑性与适应潜力差异，对其应对未来环境变化的生态与进化响应具有重要意义。