Date of Award


Degree Type


Degree Name

Master of Science in Oceanography


Biological Oceanography



First Advisor

Colleen Mouw


Phytoplankton are a diverse group of photosynthetic microorganisms and are critical components of global biogeochemical processes. Rapid changes in the U.S. Northeast Shelf (NES), a region where multiple marine heatwaves have occurred and is warming faster than the global ocean, may have far-reaching effects on ecosystems and biogeochemical processes; this study seeks to describe how these changes impact the drivers of phytoplankton abundance and community size composition within this region. Environmental drivers were characterized using multivariate modeling via partial least squares regression (PLSR) and the importance of each predictor variable was determined via variable influence on projection (VIP) scores. To illustrate the rapidly changing conditions within the NES, trends of sea surface temperature, phytoplankton abundance, and community size composition were constructed via the Theil-Sen approach. Our analyses suggest spatial variation across thermal regimes determines environmental drivers of phytoplankton abundance and community size composition within the NES. Euphotic depth is the primary environmental driver across all size classes, however, the relative impact of other drivers varies across size classes. Predictably, size classes less suited to warmer conditions are more impacted by drivers associated with these conditions. The changing community size composition, distribution, and abundance may have negative implications for biogeochemical processes within the region as well as consequences to the marine carbon cycle and food web.

Creative Commons License

Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License
This work is licensed under a Creative Commons Attribution-Noncommercial-No Derivative Works 4.0 License.



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