Phytoplankton samples were collected on May 18, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. It was a beautiful sunny day with little to no wind on Narragansett Bay. Floating dead algae were detected and the Secchi disk measured 2.2 meters. Sondes data revealed the surface water temperature was 14.23⁰C, salinity was 24.16 psu, and chlorophyll a was 3.63 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a light brown color and had a medium filter time. The tow net sample was analyzed qualitatively for microorganisms using phase contrast microscopy. The whole water sample was analyzed quantitatively under 200x phase contrast microscopy. A Hensen Stempel pipette was used to accurately deliver 1ml of sample to a Sedge-wick Rafter chamber. This analysis revealed a total of 2,328,000 cells per Liter. The micro flagellates were found at 72,000 cells/L. The most predominant phytoplankton genus was Guinardia spp. at 1,108,000 cells/L. Other representative genera include Dactyliosolen spp., Skeletonema spp., Chaetoceros spp.
200x phase contrast micrograph of Guinardia.
