<p>Filter-feeders can exert top-down and bottom-up control on phytoplankton biomass through predation and by stimulating nutrient recycling. They might also exert bottom-up control on phytoplankton community structure by altering rates and ratios of nutrient regeneration, perhaps favoring the growth of phytoplankton groups that prefer reduced forms of dissolved inorganic nitrogen (DIN) or those that require silicon (Si). Here, we use three experiments to consider whether oysters (<i>Crassostrea virginica</i>) might exert bottom-up control on coastal phytoplankton assemblages. First, we compared how rates of sediment inorganic nutrient fluxes differ between oyster-present and oyster-absent habitats. Second, we conducted an incubation experiment where we tracked changes in phytoplankton community in water overlying sediments from the oyster-present and oyster-absent habitats to test whether phytoplankton community composition might differ after several days. Finally, we conducted a feeding experiment to determine if plankton diet (i.e., dinoflagellate (<i>T-Isochrysis</i> spp.) or diatom (<i>Thalassiosira pseudonana</i>)) influenced rates of oyster respiration and excretion of dissolved inorganic nitrogen, phosphate, and Si (DIN, DIP, DSi, respectively). We observed no differences in benthic oxygen uptake or nutrient fluxes between oyster and non-oyster habitats and we observed no taxonomic shifts in phytoplankton community in the incubation experiment. In the feeding experiment, <i>C. virginica</i> respired and released DIN, DIP, but did not consume or release DSi. In addition, the observed rates were not statistically different between phytoplankton diet. These results suggest that oysters - at least <i>C. virginica</i> in temperate coastal systems - likely do not exert bottom-up control on phytoplankton community structure.</p>