Pronounced daily succession of phytoplankton, archaea and bacteria following a spring bloom

TLDR: Extending beyond the traditional view of blooms being controlled primarily by physics and inorganic nutrients, these dynamics imply highly heterogeneous, continually changing conditions over time and/or space and suggest that interactions among microorganisms are critical in controlling plankton diversity, dynamics and fates.

Abstract: Marine phytoplankton perform approximately half of global carbon fixation, with their blooms contributing disproportionately to carbon sequestration1, and most phytoplankton production is ultimately consumed by heterotrophic prokaryotes2. Therefore, phytoplankton and heterotrophic community dynamics are important in modelling carbon cycling and the impacts of global change3. In a typical bloom, diatoms dominate initially, transitioning over several weeks to smaller and motile phytoplankton4. Here, we show unexpected, rapid community variation from daily rRNA analysis of phytoplankton and prokaryotic community members following a bloom off southern California. Analysis of phytoplankton chloroplast 16S rRNA demonstrated ten different dominant phytoplankton over 18 days alone, including four taxa with animal toxin-producing strains. The dominant diatoms, flagellates and picophytoplankton varied dramatically in carbon export potential. Dominant prokaryotes also varied rapidly. Euryarchaea briefly became the most abundant organism, peaking over a few days to account for about 40% of prokaryotes. Phytoplankton and prokaryotic communities correlated better with each other than with environmental parameters. Extending beyond the traditional view of blooms being controlled primarily by physics and inorganic nutrients, these dynamics imply highly heterogeneous, continually changing conditions over time and/or space and suggest that interactions among microorganisms are critical in controlling plankton diversity, dynamics and fates. Rapid variation in the phytoplankton and bacterioplankton communities of a spring bloom provides new insights into the biological and physical parameters affecting plankton succession.