Distinct Strategies by Bloom-forming Diatoms to Frequently-encountered Shifts in Their Environmen

In the world's oceans, diatoms perform approximately 40% of the total primary production and are the most prominent group of eukaryotic phytoplankton. Recent advances in diatom genomics are revealing numerous insights into diatoms' unique evolution and metabolic adaptations that contribute to their ecological success. Here I present two studies that explore some of these distinct strategies within bloom-forming diatoms in their natural environment by combining environmental transcriptomics with additional measures of diatom physiology. First, the response to upward vertical transport during coastal upwelling events was examined. Diatoms display a distinct transcriptional response that includes frontloading nitrogen-related genes in order to outcompete other groups. Laboratory-based simulations of upwelling show that this diatom response occurs over relatively short time scales. Secondly, iron storage mechanisms were investigated with iron addition and removal incubations from varying iron environments. We show that a specific storage mechanism, the protein ferritin, may provide a competitive advantage for ferritin-utilizing diatoms in areas of the world's oceans that undergo prolonged iron limitation with pulsed iron inputs. Together, these studies provide insight into the fundamental ecological question of why diatoms are highly successful in response to frequently-encountered abiotic changes.