Metatranscriptomics reveals gene expression dynamics during an anatoxin-a producing Dolichospermum bloom in a western costal lake

Cyanobacteria harmful algae blooms in lakes are driven by nutrient and temperature fluctuations. Understanding the intricate interplay between abiotic factors and microbial community dynamics during bloom events is challenging. These challenges are compounded by highly complex, shifting communities that are impacted by various nutrient inputs and outputs over the course of a bloom event. Using deep sequencing approaches, considerable progress has been made in understanding these events, although often the underlying transcriptomic changes of taxa within bloom events is overlooked. Here, we examined a summer bloom event in Anderson Lake, which for the past two decades has predictably undergone annual blooms by a singular filamentous diazotrophic taxa Dolichospermum sp. WA102 producing anatoxin-a. Anderson Lake is relatively isolated with minimal anthropogenic impact offering an opportunity to study bloom gene expression dynamics in a more contained ecosystem. Our findings reveal the transcriptional cascades central to nutrient processing with particular emphasis on nitrogen fixation and metabolism as critical components to bloom events in both focal bloom species and accompanying communities.