Seidel Laura, Broman Elias, Ståhle Magnus, Nilsson Emelie, Turner Stephanie, Hendrycks Wouter, Sachpazidou Varvara, Forsman Anders, Hylander Samuel, Dopson Mark
Centre for Ecology and Evolution in Microbial Model Systems (EEMiS), Linnaeus University, Kalmar, Sweden.
Department of Ecology, Environment and Plant Sciences, Stockholm University, Stockholm, Sweden.
Front Microbiol. 2022 Jun 10;13:873281. doi: 10.3389/fmicb.2022.873281. eCollection 2022.
Coastal marine ecosystems are some of the most diverse natural habitats while being highly vulnerable in the face of climate change. The combination of anthropogenic influence from land and ongoing climate change will likely have severe effects on the environment, but the precise response remains uncertain. This study compared an unaffected "control" Baltic Sea bay to a "heated" bay that has undergone artificial warming from cooling water release from a nuclear power plant for ~50 years. This heated the water in a similar degree to IPCC SSP5-8.5 predictions by 2100 as natural systems to study temperature-related climate change effects. Bottom water and surface sediment bacterial communities and their biogeochemical processes were investigated to test how future coastal water warming alters microbial communities; shifts seasonal patterns, such as increased algae blooming; and influences nutrient and energy cycling, including elevated respiration rates. 16S rRNA gene amplicon sequencing and geochemical parameters demonstrated that heated bay bottom water bacterial communities were influenced by increased average temperatures across changing seasons, resulting in an overall Shannon's H diversity loss and shifts in relative abundances. In contrast, Shannon's diversity increased in the heated surface sediments. The results also suggested a trend toward smaller-sized microorganisms within the heated bay bottom waters, with a 30% increased relative abundance of small size picocyanobacteria in the summer (June). Furthermore, bacterial communities in the heated bay surface sediment displayed little seasonal variability but did show potential changes of long-term increased average temperature in the interplay with related effects on bottom waters. Finally, heated bay metabolic gene predictions from the 16S rRNA gene sequences suggested raised anaerobic processes closer to the sediment-water interface. In conclusion, climate change will likely alter microbial seasonality and diversity, leading to prolonged and increased algae blooming and elevated respiration rates within coastal waters.
沿海海洋生态系统是一些最多样化的自然栖息地，同时面对气候变化时极为脆弱。来自陆地的人为影响与持续的气候变化相结合，可能会对环境产生严重影响，但确切的反应仍不确定。本研究将一个未受影响的“对照”波罗的海海湾与一个“受热”海湾进行了比较，该“受热”海湾因核电站冷却水排放而经历了约50年的人工变暖。这种变暖程度与政府间气候变化专门委员会（IPCC）对2100年SSP5-8.5情景预测的自然系统升温程度相似，以研究与温度相关的气候变化影响。研究了底层水和表层沉积物中的细菌群落及其生物地球化学过程，以测试未来沿海水域变暖如何改变微生物群落；改变季节性模式，如藻类大量繁殖增加；并影响营养和能量循环，包括呼吸速率升高。16S rRNA基因扩增子测序和地球化学参数表明，受热海湾底层水细菌群落受到不同季节平均温度升高的影响，导致总体香农多样性损失和相对丰度变化。相比之下，受热表层沉积物中的香农多样性增加。结果还表明，受热海湾底层水中微生物有变小的趋势，夏季（6月）小型蓝细菌的相对丰度增加了30%。此外，受热海湾表层沉积物中的细菌群落季节性变化很小，但确实显示出长期平均温度升高在与对底层水的相关影响相互作用中的潜在变化。最后，根据16S rRNA基因序列对受热海湾代谢基因的预测表明，靠近沉积物-水界面的厌氧过程增加。总之，气候变化可能会改变微生物的季节性和多样性，导致沿海水域藻类大量繁殖时间延长、规模增加以及呼吸速率升高。
