Genome reconstructions indicate the partitioning of ecological functions inside a phytoplankton bloom in the Amundsen Sea Polynya, Antarctica

Phytoplankton blooms are an ecologically important yet not entirely understood phenomenon. This is certainly the case for the massive Phaeocystis blooms in climate-sensitive Antarctic polynyas. They interact with the atmosphere through the exchange of carbon dioxide and dimethylsulfide. They also sustain a distinct bacterial community that might play a role in bloom duration and intensity. Here we deeply sequenced a metagenome from an Amundsen Sea polynya bloom event and determined the genomic content of bacterial populations surrounding Phaeocystis. A pico-eukaryote genome (19.6 Mb) was also recovered. The identification of functional complementarities between P. antarctica and bacterial taxa organized in close association with Phaeocystis colonies makes a contribution to our understanding of bloom functioning in the Southern Ocean.

浮游植物水华（Phytoplankton blooms）是一类具有重要生态意义却尚未被完全阐明的自然现象。针对气候敏感的南极冰间湖（Antarctic polynyas）中大规模的棕囊藻属（Phaeocystis）水华，这一点同样成立。这类水华通过二氧化碳与二甲基硫（dimethylsulfide）的气体交换与大气进行交互，同时维系着一类独特的细菌群落，该群落或可调控水华的持续时长与强度。本研究对采自阿蒙森海冰间湖水华事件的宏基因组（metagenome）进行了深度测序，明确了棕囊藻属周围细菌种群的基因组构成，并恢复得到一个19.6 Mb的超微真核生物（pico-eukaryote）基因组。本研究鉴定出南极棕囊藻（Phaeocystis antarctica, P. antarctica）与紧密附着于棕囊藻藻集落的细菌类群之间存在功能互补性，这一发现有助于深化我们对南大洋浮游植物水华运行机制的理解。