Abstract
Picophytoplankton are a group of photosynthetic, unicellular organisms, making them key primary producers in aquatic ecosystems. These cells numerically dominate in oceans and lakes where picophytoplankton communities contain phenotypic subpopulations that correspond to biogeographic patterns. In rivers, however, such community dynamics are less studied. We examined the phenotypic subpopulations of picophytoplankton in two converging urban river environments of Portland, Oregon (USA): the Columbia and the Willamette Rivers. From September 2022 through July 2023, we took roughly bi-weekly surface water samples and used multi-laser flow cytometry to distinguish between photosynthetic cells based on their size and pigment fluorescence. We discovered seven distinct subpopulations of picophytoplankton. Subpopulations with similar pigment fluorescence ratios were observed in both rivers, but changes in their abundances over time differed. Our data suggest that unique hydrological environments can support coexisting phenotypes of picophytoplankton in the surface waters of rivers.
Recommended Citation
Lamberson, Kylee M.; Wendlandt, Camille E.; Forgrave, Kristin E.; and Thompson, Anne W.
(2026)
"Temporal variation in picophytoplankton pigment phenotypes of two urban rivers,"
International Journal of Undergraduate Research and Creative Activities: Vol. 18:
Iss.
1, Article 2.
DOI: https://doi.org/10.61809/2168-0620.1413
Available at:
https://digitalcommons.cwu.edu/ijurca/vol18/iss1/2