Patterns and Drivers of Diatom Diversity and Biogeography in the North Pacific
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Marine diatoms contribute to about 20% of global primary production. We present the first basin-scale, multiyear assessment of diatom communities in the North Pacific, combining taxonomically high-resolution RuBisCO large subunit gene ( rbcL ) metabarcoding with concurrent environmental measurements. Using a nine-year time series of daily samples resolved at the species level via ∼500 bp rbcL fragments, we performed multivariate analyses across biogeographic provinces, identifying significant correlations between community structure and environmental drivers such as temperature and macronutrient availability.
We report the prevalence of a previously overlooked centric diatom species in the North Pacific, Eunotogramma lunatum , which appears to be near-dominant even in subarctic high-nitrate, low-chlorophyll waters where pennate diatoms are typically favored.
These results demonstrate the power of rbcL for large-scale ocean monitoring and provide a critical baseline for future studies of diatom population dynamics, climate change impacts, and ecosystem resilience in a key marine region.
Diatoms are among the ocean’s most important primary producers, yet large-scale, long-term assessments of their diversity have been limited by the resolution of traditional monitoring methods. This study provides the first basin-scale, multiyear baseline of diatom community structure across the North Pacific, demonstrating that genetic metabarcoding can resolve species-level diversity at a scale and resolution previously unattainable. By linking nine years of daily samples to concurrent environmental data, we show that temperature and nutrient availability are among the key predictors of community composition across distinct biogeographic regions. These findings establish a critical reference point for tracking how diatom communities – and the ecological services they underpin, including carbon export and marine food web support – may shift in response to ongoing climate change.
