Ocean acidification has a strong effect on communities living on plastic in mesocosms

We conducted a mesocosm experiment to examine how ocean acidification (OA) affects communities of prokaryotes and eukaryotes growing on single-use drinking bottles in subtropical eutrophic waters of the East China Sea. Based on 16S rDNA gene sequencing, simulated high CO2 significantly altered the prokaryotic community, with the relative abundance of the phylum Planctomycetota increasing by 49 % under high CO2. Under high CO2, prokaryotes in plastisphere significantly enhanced nitrogen dissimilation and ureolysis, raising the possibility that elevated CO2 may modify nutrient cycling in subtropical eutrophic waters. The relative abundance of pathogenic and animal parasite bacteria also increased under simulated high CO2. Our results show that simulated high CO2 significantly affected some secondary producers based on 18S rDNA gene sequencing. For example, Mayorella amoebae were highly resistant to OA whereas labyrinthulids were sensitive to high CO2. This shows that OA may alter plastisphere food chains in subtropical eutrophic waters.

本研究开展了中型实验生态系统实验（mesocosm experiment），以探究海洋酸化（ocean acidification, OA）对东中国海亚热带富营养化水体中附着于一次性饮用水瓶表面的原核生物与真核生物群落的影响。基于16S rDNA基因测序结果，模拟高CO₂环境显著改变了原核生物群落结构；其中浮霉菌门（Planctomycetota）的相对丰度在高CO₂条件下提升了49%。在高CO₂环境下，塑料圈（plastisphere）内的原核生物显著增强了氮异化作用与尿素分解作用，这提示CO₂浓度升高可能会改变亚热带富营养化水体中的养分循环过程。模拟高CO₂条件下，致病细菌与动物寄生细菌的相对丰度同样出现上升。基于18S rDNA基因测序结果，本研究发现模拟高CO₂环境会显著影响部分次级生产者。例如，Mayorella变形虫（Mayorella amoebae）对海洋酸化具有极强的耐受性，而迷宫虫类（labyrinthulids）则对高CO₂环境敏感。该结果表明，海洋酸化可能会改变亚热带富营养化水体中的塑料圈食物链。