Metatranscriptomics of phytoplankton communities from the Western Antarctic Peninsula

The continental shelf of the Western Antarctic Peninsula (WAP) is a highly variable system characterized by strong cross-shelf gradients, rapid regional climate change and large blooms of phytoplankton, notably diatoms. Despite progress identifying the important environmental factors influencing plankton community composition in the WAP, the molecular basis for variations in species abundance, metabolism and distribution remain largely unresolved. In this study, we identified oceanographic variables along the WAP that influence eukaryotic phytoplankton composition and the metabolic profiles of phytoplankton with an emphasis on expression patterns of iron-related genes in diatoms as assessed through metatranscriptomic sequencing. Distinct phytoplankton communities and metabolisms closely mirrored the strong gradients in oceanographic parameters that existed from coastal to offshore regions. Diatoms were abundant in coastal, southern regions, where colder and fresher waters were conducive to a bloom of the centric diatom, Actinocyclus. The metatranscriptomic survey performed here revealed functional differences in diatom communities and provides further insight into the environmental factors influencing the growth of diatoms and their predicted response to changes in ocean conditions.