Phytoplankton Sampling

Phytoplankton samples were collected on May 3, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sondes data revealed the surface water temperature was 13.37⁰C, salinity was 6.62 psu, and chlorophyll a was 1.86 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a light brown color and had a quick filter time. There was lots of zooplankton activity in today’s sample. 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 214,000 cells per Liter. The micro flagellates were found at 7,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 87,000 cells/L. Representative genera in the tow net sample include Thalassionema spp., Leptocylindrus spp. and pennate diatoms.

 200x phase contrast micrograph of Fragilaria spp.

Phytoplankton samples were collected on March 22, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. It was a brisk day with some cloud cover. The current was very strong and some seals were spotted in Narragansett Bay. Sondes data revealed the surface water temperature was 7.03⁰C, salinity was 13.76 psu, and chlorophyll a was 1.26 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a deep 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 108,000 cells per Liter. The micro flagellates were found at 4000 cells/L. The most predominant phytoplankton genus was Thalassionema spp. at 36,000 cells/L. Representative genera in the tow net sample include Skeletonema spp., Leptocylindrus spp. and pennate diatoms. 

200x phase contrast image of Polykrikos spp.

​Phytoplankton samples were collected on February 23, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sondes data revealed the surface water temperature was 5.49⁰C, salinity was 26.72 psu, and chlorophyll a was 3.26 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a dark yellow/golden brown color and had a quick 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 7,824,000 cells per Liter. The most predominant phytoplankton genus was Skeletonema spp. at 7,408,000. Representative genera in the tow net sample include Thalassiosira spp., Asterionellopsis spp., and Leptocylindrus spp. 

200x phase contrast image of diatomic phytoplankton.