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Abstract Picophytoplankton are a ubiquitous component of marine plankton communities and are expected to be favored by global increases in seawater temperature and stratification associated with climate change. Eukaryotic and prokaryotic picophytoplankton have distinct ecology, and global models predict that the two groups will respond differently to future climate scenarios. At a nearshore observatory on the Northeast US Shelf, however, decades of year‐round monitoring have shown these two groups to be highly synchronized in their responses to environmental variability. To reconcile the differences between regional and global predictions for picophytoplankton dynamics, we here investigate the picophytoplankton community across the continental shelf gradient from the nearshore observatory to the continental slope. We analyze flow cytometry data from 22 research cruises, comparing the response of picoeukaryote andSynechococcuscommunities to environmental variability across time and space. We find that the mechanisms controlling picophytoplankton abundance differ across taxa, season, and distance from shore. Like the prokaryote,Synechococcus, picoeukaryote division rates are limited nearshore by low temperatures in winter and spring, and higher temperatures offshore lead to an earlier spring bloom. UnlikeSynechococcus, picoeukaryote concentration in summer decreases dramatically in offshore surface waters and exhibits deeper subsurface maxima. The offshore picoeukaryote community appears to be nutrient limited in the summer and subject to much greater loss rates thanSynechococcus. This work both produces and demonstrates the necessity of taxon‐ and site‐specific knowledge for accurately predicting the responses of picophytoplankton to ongoing environmental change.
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Abundance of eukaryote picophytoplankton and Synechococcus from a moored submersible flow cytometer at Martha's Vineyard Coastal Observatory, ongoing since 2003 (NES-LTER since 2017)
This is a 19-year time series of the abundance of eukaryote picophytoplankton and Synechococcus at 4 meters depth at the Martha's Vineyard Coastal Observatory, about 3 km south of Katama Beach, Edgartown, Massachusetts, USA. Picophytoplankton were sensed in situ by a submersible flow cytometer (FlowCytobot, or FCB). Sampling frequency was continuous at approximately 20-minute intervals binned to hourly resolution with some exceptions (e.g., winter in some years). This time series is ongoing for Northeast U.S. Shelf Long-Term Ecological Research (NES-LTER).
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- Award ID(s):
- 1655686
- PAR ID:
- 10512915
- Publisher / Repository:
- Environmental Data Initiative
- Date Published:
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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