Experiment: Physiological responses of the calcifying rhodophyte, Corallina officinalis (L.), to future CO2 levels

Future atmospheric CO2 levels will most likely have complex consequences for marine organisms, particulary photosynthetic calcifying organisms. Corallina officinalis L. is an erect calcifying macroalga found in the inter- and subtidal regions of temperate rocky coastlines and provides important substrate and refugia for marine meiofauna. The main goal of the current study was to determine the physiological responses of C. officinalis to increased CO2 concentrations expected to occur within the next century and beyond. Our results show that growth and production of inorganic material decreased under high CO2 levels, while carbonic anhydrase activity was stimulated and negatively correlated to algal inorganic content. Photosynthetic efficiency based on oxygen evolution was also negatively affected by increased CO2. The results of this study indicate that C. officinalis may become less competitive under future CO2 levels, which could result in structural changes in future temperate intertidal communities.

未来大气二氧化碳浓度极有可能对海洋生物产生复杂影响，尤其对于光合钙化生物（photosynthetic calcifying organisms）。珊瑚藻（Corallina officinalis L.）为直立生长的钙化大型藻类，分布于温带岩质海岸的潮间带及潮下带区域，可为海洋小型底栖生物（marine meiofauna）提供重要的附着基质与庇护场所。本研究的核心目标，旨在探究珊瑚藻（C. officinalis）对未来一个世纪及更久远时期预计升高的二氧化碳浓度的生理响应。研究结果显示：高二氧化碳浓度环境下，该藻类的生长速率与无机钙化物质合成量均出现下降；而碳酸酐酶（carbonic anhydrase）活性则被激活，且与藻类的无机物质含量呈负相关关系。基于放氧速率测定的光合效率，同样受到二氧化碳浓度升高的负面影响。本研究结果表明，在未来二氧化碳浓度升高的环境中，珊瑚藻的竞争能力可能会下降，进而可能引发温带潮间带群落的结构改变。