Phytoplankton Sampling

A phytoplankton sample was collected on October 4, 2023 at Bullock’s Reach and analyzed in the laboratory shortly after collection. The plankton tow-net sample was not collected this week, only the whole-water quantitative sample. Sonde data revealed the surface water temperature was 18.50°C, salinity was 18.15 psu, and chlorophyll a was 4.23 ug/L. 

The whole water sample was analyzed and revealed a total of 676,000 cells per Liter. The micro flagellates were found at 554,000 cells/L. The most predominant phytoplankton genus was Chaetoceros spp.at 78,000 cells/L. Other representative genera include Eucampia spp. (see 400x phase contrast image below), Skeletonema spp., and Gonyaulax spp.

Phytoplankton samples were collected on September 20, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sonde data revealed the surface water temperature was 19.3°C, salinity was 24.5 psu, and chlorophyll a was 12.2 ug/L. The plankton tow net filtrate was a light brown color and had a long filter time. High particulates and comb jelly fish were detected. The whole water sample was analyzed and revealed a total of 76,000 cells per Liter.  The micro flagellates were found at 28,000 cells/L. The most predominant phytoplankton genus was Leptocylindrus spp.at 27,000 cells/L. Other representative genera include Skeletonema spp. and Chaetoceros spp. Today’s featured micrograph shows a centric diatom at 400x phase contrast. 

Phytoplankton samples were collected on September 6, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sonde data revealed the surface water temperature was 23.4°C, salinity was 24.5 psu, and chlorophyll a was 12.2 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a light brown greenish color and had a long 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 2,856,000 cells per Liter. The micro flagellates were found at 108,000 cells/L. The most predominant phytoplankton genus was Leptocylindrus spp.at 2,196,000 cells/L. Other representative genera include Skeletonema spp., Chaetoceros spp., and Eucampia spp., the subject of the 200x phase contrast micrograph shown below. 

Phytoplankton samples were collected on August 23, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sonde data revealed the surface water temperature was 21.0°C and salinity was 26.5 psu. 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. 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 1,866,000 cells per Liter. The micro flagellates were found at 348,000 cells/L. The most predominant phytoplankton genus was Leptocylindrus spp.at 948,000 cells/L. Other representative genera include Skeletonema spp., Chaetoceros spp. (see 200x phase contrast image below), and Guinardia spp.

Phytoplankton samples were collected on August 9, 2023 at Bullock’s Reach and analyzed in the laboratory shortly after collection. Sonde data revealed the surface water temperature was 23.4°C, salinity was 24.1 psu, and chlorophyll a was 7.2 ug/L.  The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a light brown greenish color and had a long filter time. Lots of activity was present in the sample and comb jellies were detected. 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 89,000 cells per Liter. The micro flagellates were found at 70,000 cells/L. The most predominant phytoplankton genus was Dinophysis spp.at 4,000 cells/L. Other representative genera include Scripsiella spp., Guinardia spp., Eutreptiella spp., and Polykrikos spp., the featured plankton taxon in the 200x phase contrast micrograph below. 

​Phytoplankton samples were collected on July 26, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. Sondes data revealed the surface water temperature was 25.586⁰C, salinity was 16.22psu, and chlorophyll a was 19.77 ug/L. It was a hot and humid day with calm conditions on Narragansett Bay. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a light tan color and had a quick filter time. Some small comb jellies were detected. 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 462,000 cells per Liter. The micro flagellates were found at 376,000 cells/L. The most predominant phytoplankton genus was Heterocapsa spp. at 38,000 cells/L. Other representative genera include Guinardia spp., Thalassiosira spp., and Eutreptiella spp.

 200x phase contrast micrograph of Eucampia spp.

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.