Assessing the physiological responses of the gastropod Crepidula fornicata to predicted ocean acidification and warming@en

Organisms inhabiting coastal waters naturally experience diel and seasonal physico-chemical variations. According to various assumptions, coastal species are either considered to be highly tolerant to environmental changes or, conversely, living at the thresholds of their physiological performance. Therefore, these species are either more resistant or more sensitive, respectively, to ocean acidification and warming. Here, we focused on Crepidula fornicata, an invasive gastropod that colonized bays and estuaries on northwestern European coasts during the 20th century. Small (<3 cm in length) and large (>4.5 cm in length), sexually mature individuals of C. fornicata were raised for 6 months in three different pCO2 conditions (390 µatm, 750 µatm, and 1400 µatm) at four successive temperature levels (10°C, 13°C, 16°C, and 19°C). At each temperature level and in each pCO2 condition, we assessed the physiological rates of respiration, ammonia excretion, filtration and calcification on small and large individuals. Results show that, in general, temperature positively influenced respiration, excretion and filtration rates in both small and large individuals. Conversely, increasing pCO2 negatively affected calcification rates, leading to net dissolution in the most drastic pCO2 condition (1400 µatm) but did not affect the other physiological rates. Overall, our results indicate that C. fornicata can tolerate ocean acidification, particularly in the intermediate pCO2 scenario. Moreover, in this eurythermal species, moderate warming may play a buffering role in the future responses of organisms to ocean acidification.栖息于沿海水域的生物，天然会经历昼夜与季节尺度的物理化学波动。基于不同假设，沿海物种要么被认为对环境变化具备高度耐受性，要么恰恰相反，其生存处于生理性能的临界阈值区间。因此，这类物种对海洋酸化与增温的响应或表现为更强抗性，或更为敏感。 本研究聚焦于履螺（Crepidula fornicata）——一种于20世纪入侵欧洲西北海岸海湾与河口的腹足类物种。本研究将体长小于3cm与大于4.5cm的性成熟个体，分别置于3种不同二氧化碳分压（pCO2）条件（390 µatm、750 µatm及1400 µatm）与4个连续温度梯度（10°C、13°C、16°C及19°C）下培养6个月。 在每个温度梯度与pCO2条件下，我们分别测定了不同大小个体的呼吸、氨排泄、滤食及钙化生理速率。 实验结果总体显示，温度对两类个体的呼吸、排泄与滤食速率均存在正向影响；而升高的pCO2仅对钙化速率产生负向影响：在最极端的pCO2条件（1400 µatm）下，出现了钙化的净溶解现象，但并未影响其余生理速率。 整体而言，本研究结果表明，履螺可耐受海洋酸化环境，在中等pCO2情境下耐受性尤为显著。此外，对于这种广温性物种而言，适度增温或许能在未来生物应对海洋酸化的响应过程中发挥缓冲作用。