Zhao Liqiang, Harvey Ben P, Higuchi Tomihiko, Agostini Sylvain, Tanaka Kentaro, Murakami-Sugihara Naoko, Morgan Holly, Baker Phoebe, Hall-Spencer Jason M, Shirai Kotaro
College of Fisheries, Guangdong Ocean University, Zhanjiang 524088, China; Atmosphere and Ocean Research Institute, The University of Tokyo, Chiba 277-8564, Japan.
Shimoda Marine Research Center, University of Tsukuba, Shimoda 415-0025, Japan.
Sci Total Environ. 2023 May 15;873:162293. doi: 10.1016/j.scitotenv.2023.162293. Epub 2023 Feb 21.
Ocean acidification can severely affect bivalve molluscs, especially their shell calcification. Assessing the fate of this vulnerable group in a rapidly acidifying ocean is therefore a pressing challenge. Volcanic CO seeps are natural analogues of future ocean conditions that offer unique insights into the scope of marine bivalves to cope with acidification. Here, we used a 2-month reciprocal transplantation of the coastal mussel Septifer bilocularis collected from reference and elevated pCO habitats to explore how they calcify and grow at CO seeps on the Pacific coast of Japan. We found significant decreases in condition index (an indication of tissue energy reserves) and shell growth of mussels living under elevated pCO conditions. These negative responses in their physiological performance under acidified conditions were closely associated with changes in their food sources (shown by changes to the soft tissue δC and δN ratios) and changes in their calcifying fluid carbonate chemistry (based on shell carbonate isotopic and elemental signatures). The reduced shell growth rate during the transplantation experiment was further supported by shell δC records along their incremental growth layers, as well as their smaller shell size despite being of comparable ontogenetic ages (5-7 years old, based on shell δO records). Taken together, these findings demonstrate how ocean acidification at CO seeps affects mussel growth and reveal that lowered shell growth helps them survive stressful conditions.
海洋酸化会严重影响双壳贝类软体动物，尤其是它们的贝壳钙化过程。因此，评估这一脆弱群体在快速酸化的海洋中的命运是一项紧迫的挑战。火山二氧化碳渗漏是未来海洋状况的自然模拟物，能为海洋双壳贝类应对酸化的能力范围提供独特见解。在此，我们对从对照和高pCO₂栖息地采集的沿海贻贝——双隔贻贝进行了为期两个月的 reciprocal transplantation，以探究它们在日本太平洋沿岸的二氧化碳渗漏处如何钙化和生长。我们发现，生活在高pCO₂条件下的贻贝，其状况指数（组织能量储备的指标）和贝壳生长显著下降。在酸化条件下，它们生理性能的这些负面反应与食物来源的变化（通过软组织δC和δN比值的变化显示）以及钙化液碳酸盐化学的变化（基于贝壳碳酸盐同位素和元素特征）密切相关。移植实验期间贝壳生长速率的降低，进一步得到了沿其增量生长层的贝壳δC记录的支持，以及尽管它们的个体发育年龄相当（基于贝壳δO记录为5至7岁）但贝壳尺寸较小的支持。综上所述，这些发现证明了二氧化碳渗漏处的海洋酸化如何影响贻贝生长，并揭示出贝壳生长降低有助于它们在压力条件下生存。
