Phytoplankton Sampling

Phytoplankton samples were collected on July 12, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sondes data revealed the surface water temperature was 25.529⁰C, salinity was 21.40 psu, and chlorophyll a was 11.25 ug/L. Small sea jellies were observed today on Narragansett Bay. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a green- tan 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 1,124,000 cells per Liter. The micro flagellates were found at 198,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp.at 772,000 cells/L. Other representative genera include Chaetoceros spp., Thalassiosira spp., and Eutreptiella spp.

200x phase contrast image of Protoperidinium spp.

Phytoplankton samples were collected on June 28, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sondes data revealed the surface water temperature was 22.945⁰C, salinity was 23.18 psu, and chlorophyll a was 4.71 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a green- 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 5,670,000 cells per Liter. The micro flagellates were found at 25,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp.at 4,400,000 cells/L. Other representative genera include Chaetoceros spp., Gonyaulax spp., and Leptocylindrus spp.​

100x phase contrast micrograph of the qualitative tow net sample.

Phytoplankton samples were collected on May 31, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sondes data revealed the surface water temperature was 18.11⁰C, salinity was 21.04 psu, and chlorophyll a was 4.88 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a light tan/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 16,860,000 cells per Liter.  The micro flagellates were found at 525,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 15,585,000 cells/L. These plankton were found in chains of 6 cells. Other representative genera include Guinardia spp., Chaetoceros spp., and Leptocylindrus spp.

200x phase contrast micrograph of Skeletonema spp.

​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.

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.