SEASONAL VARIABILITY OF THE MICROZOOPLANKTON COMMUNITY STRUCTURE ON THE NORTHEAST US SHELF

Phytoplankton grazing by microzooplankton is a critical step in making material and energy available to higher trophic levels, and therefore shapes marine food webs as well as biogeochemical cycles. Understanding the drivers of microzooplankton grazing requires understanding the key players through quantification and description of the microzooplankton biomass and community composition. This study leverages samples collected in boreal summer and winter from 2018-2023, at three stations spanning the Northeast US Shelf from coastal Rhode Island to the shelf break, resulting in a dataset of microzooplankton biomass that encompasses the seasonal, temporal, and spatial variability of this continental shelf ecosystem. Using semi-automated image analysis, we estimated biomass for two key microzooplankton groups, dinoflagellates and ciliates, collected in the context of the Northeast US Shelf Long Term Ecological Research Program. Results reveal a strong seasonal pattern in dinoflagellates, with large dinoflagellates contributing 61% of total microzooplankton biomass in winter, and 34% in summer, while small dinoflagellates contributed only 10% of total microzooplankton biomass in winter, and 42% in summer. Ciliate biomass did not demonstrate a strong seasonal signal. These results can inform our understanding of planktonic food webs by further constraining the drivers of phytoplankton community structure and energy transfer to higher trophic levels.

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Primary Presenter: Frankie Lopez, University of Rhode Island (frankie.lopez@uri.edu)

Authors:

Frankie Lopez, University of Rhode Island  (frankie.lopez@uri.edu)

Pierre Marrec, University of Rhode Island  (pmarrec@uri.edu)

Susanne Menden-Deuer, University of Rhode Island  (smenden@uri.edu)