Phytoplankton Sampling

Phytoplankton samples were collected on October 30, 2024 at Bullock’s Reach and analyzed in the laboratory shortly after collection. Weather conditions and Sonde data were not recorded on this day. The qualitative tow net sample had a moderate filtration time. The filtrate was slightly cloudy with some golden brown particulates. The analysis of the quantitative whole water sample revealed a total of 260,000 cells/L. The microflagellates were found at 100,000 cells/L. The most predominant phytoplankton genera were Chaetoceros spp. at 104,000 cells/L, Leptocylindrus spp. at 26,000 cells/L, and Skeletonema spp. at 18,000 cells/L. Proboscia alata, shown here in a 100x phase contrast micrograph, is a solitary or chain-forming diatom that can measure up to 1mm in length. They are identified by the presence of a proboscis with a truncated tip and offset claspers. These diatoms are an oceanic, temperate water species and are sometimes found near the coast.

Phytoplankton samples were collected on May 1, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. It was a cold and breeze day on Narragansett Bay with cloudy conditions. The qualitative tow net sample had a long filtration time, and the filtrate was a reddish brown and slightly cloudy.

The analysis of the quantitative whole water sample revealed a total of 4,006,000 cells per Liter. The micro flagellates were found at 24,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 1,646,000 cells/L. Other representative genera include Thalassiosira spp., Leptocylindrus spp., and Chaetoceros spp. This week’s featured image is Eucampia spp. (200x phase contrast), a type of diatomic phytoplankton that is often found in the North Atlantic Ocean. This genus is often found in a curved form and in helical chains. This diatom is yellow-brown in color with numerous green chloroplasts.

​Phytoplankton samples were collected on March 20, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. It was partly sunny, breeze and brisk on Narragansett Bay. The qualitative tow net sample had a long filtration time, and the filtrate was a dark brown color. Some sediment and jellyfish were found in the sample. 

The analysis of the quantitative whole water sample revealed a total of 3,536,000 cells per Liter. The micro flagellates were found at 20,000 cells/L. The most predominant phytoplankton genus was Thalassiosira spp. at 1,888,000 cells/L. Other representative genera include Skeletonema spp. and Leptocylindrus spp.​ Thalassiosira spp. (today’s featured micrograph, 200x phase contrast) is a type of ​​phytoplankton belonging to the centric diatom group. This photosynthetic species grows primarily in marine waters. Some species within the genus are found in estuaries and aquatic systems that have been impacted by human activities. They can be identified by their coin-like shape.

Phytoplankton samples were collected on October 18, 2023 at Bullock’s Reach and analyzed in the laboratory shortly after collection. It was a cloudy and chilly day on Narragansett Bay. The water was noticeably clear to almost 5 meters depth. Sonde data revealed the surface water temperature was 15.8°C, salinity was 24.9 psu, and chlorophyll a was 7.85 ug/L. The qualitative tow net sample had a medium filter time, and the filtrate was a light brown color. Some comb jellyfish were detected in the sample.

The analysis of the quantitative whole water sample revealed a total of 1,997,000 cells per Liter. The micro flagellates were found at 419,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 1,255,000 cells/L. Other representative genera include Chaetoceros spp., Leptocylindrus spp., and Cerataulina spp.​​ ​This week’s featured image is the diatom Ditylum brightwellia, captured at 200x phase contrast.

 

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.