Molecular physiology of Antarctic diatom natural assemblages and bloom event reveal insights into strategies contributing to their ecological success

• Published in: mSystems
• Main Authors: Carly M. Moreno, Margaret Bernish, Meredith G. Meyer, Zuchuan Li, Nicole Waite, Natalie R. Cohen, Oscar Schofield, Adrian Marchetti
• Format: Article in Journal/Newspaper
• Language: English
• Published: American Society for Microbiology 2024
• Subjects: polar diatoms; microbial ecology; metatranscriptome; Western Antarctic Peninsula; oceanography; Microbiology; QR1-502; Antarc*; Antarctic; Antarctic Peninsula; Southern Ocean
• Online Access: https://doi.org/10.1128/msystems.01306-23; https://doaj.org/article/7ed4ca263612483b95cb8f2826c23068

ABSTRACTThe continental shelf of the Western Antarctic Peninsula (WAP) is a highly variable system characterized by strong cross-shelf gradients, rapid regional change, and large blooms of phytoplankton, notably diatoms. Rapid environmental changes coincide with shifts in plankton community composition and productivity, food web dynamics, and biogeochemistry. Despite the progress in identifying important environmental factors influencing plankton community composition in the WAP, the molecular basis for their survival in this oceanic region, as well as variations in species abundance, metabolism, and distribution, remains largely unresolved. Across a gradient of physicochemical parameters, we analyzed the metabolic profiles of phytoplankton 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. Members of this genus invested heavily in growth and energy production; carbohydrate, amino acid, and nucleotide biosynthesis pathways; and coping with oxidative stress, resulting in uniquely expressed metabolic profiles compared to other diatoms. We observed strong molecular evidence for iron limitation in shelf and slope regions of the WAP, where diatoms in these regions employed iron-starvation induced proteins, a geranylgeranyl reductase, aquaporins, and urease, among other strategies, while limiting the use of iron-containing proteins. The metatranscriptomic survey performed here reveals 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.IMPORTANCEIn the Southern Ocean, phytoplankton must cope with harsh environmental conditions such as low light and growth-limiting ...