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学意义但尚未被完全阐明的自然现象。在对气候变化敏感的南极冰间湖（Antarctic polynyas）中大规模爆发的棕囊藻（Phaeocystis）水华，正是这类现象的典型代表。此类水华可通过二氧化碳（carbon dioxide）与二甲基硫（dimethylsulfide）的交换与大气发生相互作用，同时维系着一套独特的细菌群落，该群落或对水华的持续时长与强度产生调控作用。本研究对阿蒙森海（Amundsen Sea）冰间湖某次水华事件的宏基因组（metagenome）进行了深度测序，解析了棕囊藻周边细菌种群的基因组组成；此外还重建获得了一个大小为19.6 Mb的微型真核生物（pico-eukaryote）基因组。本研究鉴定出南极棕囊藻（Phaeocystis antarctica）与紧密依附于棕囊藻集落的细菌类群之间存在功能互补关系，这一发现有助于加深学界对南大洋（Southern Ocean）浮游植物水华生态功能的认知。