Hall Clio Abbie Marjorie, Henry Nicolas, Canals Oriol, Consing Gianina, Rodríguez-Ezpeleta Naiara, Lewandowska Aleksandra M
Tvärminne Zoological Station University of Helsinki Hanko Finland.
CNRS, Sorbonne Université, FR2424, ABiMS, Station Biologique de Roscoff Roscoff France.
Ecol Evol. 2025 Sep 15;15(9):e72125. doi: 10.1002/ece3.72125. eCollection 2025 Sep.
Climate change is transforming marine ecosystems, with rising temperatures and changing salinity patterns expected to reshape plankton communities in the Baltic Sea. As key components of marine food webs and biogeochemical cycles, plankton are highly sensitive to environmental change. Here, we examined the effects of warming and salinity change on plankton communities using a mesocosm experiment at the Tvärminne Zoological Station, Finland. We employed both traditional microscopy-based identification and DNA metabarcoding (18S rRNA and COI markers) to assess shifts in phytoplankton, ciliates and mesozooplankton. Our findings indicate that salinity primarily affected higher trophic levels, while warming influenced lower ones. Warmer conditions increased community evenness and favoured mixotrophic and heterotrophic taxa, whereas salinity effects were most pronounced in rotifers and copepods, reflecting species-specific tolerances. Interactive effects varied, with salinity sometimes buffering warming impacts and other times intensifying them, highlighting complex stressor interactions. Microscopy allowed for a more precise quantification of plankton abundance, whereas metabarcoding captured a broader taxonomic diversity. Our results suggest that, within the tested salinity range (3-10.5 PSU), higher salinities supported a more classical marine food web structure, characterised by larger and more complex zooplankton such as copepods. In contrast, freshening and warming conditions were associated with shifts towards smaller, mixotrophic and bloom-forming plankton taxa, with potential consequences for ecosystem functioning. This study highlights metabarcoding's value in mesocosm research while emphasising the need to refine molecular techniques for ecological interpretations.
气候变化正在改变海洋生态系统，预计气温上升和盐度模式变化将重塑波罗的海的浮游生物群落。作为海洋食物网和生物地球化学循环的关键组成部分，浮游生物对环境变化高度敏感。在此，我们在芬兰图尔库动物园站通过中宇宙实验研究了变暖和盐度变化对浮游生物群落的影响。我们采用传统的基于显微镜的鉴定方法以及DNA宏条形码技术（18S rRNA和细胞色素氧化酶亚基I标记）来评估浮游植物、纤毛虫和中型浮游动物的变化。我们的研究结果表明，盐度主要影响较高营养级，而变暖影响较低营养级。较温暖的条件增加了群落均匀度，并有利于混合营养和异养类群，而盐度影响在轮虫和桡足类中最为明显，反映了物种特异性耐受性。交互作用各不相同，盐度有时缓冲变暖影响，有时则加剧变暖影响，突出了复杂的应激源相互作用。显微镜检查能够更精确地量化浮游生物丰度，而宏条形码技术能够捕捉更广泛的分类多样性。我们的结果表明，在测试的盐度范围内（3-10.5实用盐度单位），较高的盐度支持更典型的海洋食物网结构，其特征是存在更大、更复杂的浮游动物，如桡足类。相比之下，淡水化和变暖条件与向更小、混合营养和形成水华的浮游生物类群的转变有关，这可能对生态系统功能产生影响。这项研究突出了宏条形码技术在中宇宙研究中的价值，同时强调了完善分子技术以进行生态学解释的必要性。
