Aix-Marseille Université, Université de Toulon, CNRS, IRD, Mediterranean Institute of Oceanography (MIO, UM 110), Marseille, France.
Department of Experimental Limnology, Leibniz Institute of Freshwater Ecology and Inland Fisheries, Stechlin, Germany.
ISME J. 2021 Jun;15(6):1695-1708. doi: 10.1038/s41396-020-00880-z. Epub 2021 Jan 15.
The vertical flux of marine snow particles significantly reduces atmospheric carbon dioxide concentration. In the mesopelagic zone, a large proportion of the organic carbon carried by sinking particles dissipates thereby escaping long term sequestration. Particle associated prokaryotes are largely responsible for such organic carbon loss. However, links between this important ecosystem flux and ecological processes such as community development of prokaryotes on different particle fractions (sinking vs. non-sinking) are yet virtually unknown. This prevents accurate predictions of mesopelagic organic carbon loss in response to changing ocean dynamics. Using combined measurements of prokaryotic heterotrophic production rates and species richness in the North Atlantic, we reveal that carbon loss rates and associated microbial richness are drastically different with particle fractions. Our results demonstrate a strong negative correlation between prokaryotic carbon losses and species richness. Such a trend may be related to prokaryotes detaching from fast-sinking particles constantly enriching non-sinking associated communities in the mesopelagic zone. Existing global scale data suggest this negative correlation is a widespread feature of mesopelagic microbes.
海洋雪颗粒的垂直通量显著降低了大气二氧化碳浓度。在中层带，大量由下沉颗粒携带的有机碳消散，从而避免了长期的封存。与颗粒相关的原核生物在这种有机碳损失中起主要作用。然而，这种重要的生态系统通量与生态过程（例如不同颗粒（下沉与非下沉）上原核生物的群落发展）之间的联系实际上还鲜为人知。这使得无法准确预测海洋中层有机碳对海洋动力学变化的损失。通过对北大西洋原核生物异养生产力和物种丰富度的综合测量，我们发现碳损失率和相关微生物丰富度与颗粒分数有很大的不同。我们的结果表明，原核生物的碳损失与物种丰富度之间存在强烈的负相关关系。这种趋势可能与原核生物不断从快速下沉的颗粒上脱落有关，从而使中层带中非下沉相关的群落中富含更多的物种。现有的全球尺度数据表明，这种负相关是海洋中层微生物的一个普遍特征。
