News – Page 24 – Narrabay

January 10, 2024

Nutrient samples were collected from 12 river stations on January 10th. In the five days prior to sampling and the morning of, there were 4.67 inches of precipitation recorded at T.F. Green.

Among the stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) concentrations were observed at Ten Mile River @ Roger Williams Ave (TN = 1,840 ppb, TDN = 1,780 ppb, DIN = 1,620 ppb). The lowest TN was observed at Runnins River @ River Rd (556 ppb), while the lowest TDN and DIN were observed at Taunton River @ Berkley Bridge (TDN = 419 ppb, DIN = 155 ppb).

The next scheduled sampling date is January 24, 2024.

July 3, 2024

Water clarity was measured at seven locations in the Providence River and Seekonk River estuary on July 3rd, 2024. Rainfall totaling 1.53 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 1.5 meters, compared to 2.22 meters on the previous survey (June 17th). The lowest clarity this week (0.8 meters) was measured at Phillipsdale Landing, while the greatest clarity (1.8 meters) was measured at Conimicut Point and Point St. Bridge. There was a general north-to-south gradient of increasing water clarity among the sites this week.

June 17, 2024

Water clarity was measured at seven locations in the Providence River and Seekonk River estuary on June 17th, 2024. Rainfall totaling 0.06 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.2 meters, compared to 2.0 meters on the previous survey (June 12th). The lowest clarity this week (1.2 meters) was measured at Phillipsdale Landing, while the greatest clarity (3.3 meters) was measured at Conimicut Point. There was a general north-to-south gradient of increasing water clarity among the sites this week.

June 12, 2024

Water clarity was measured at seven locations in the Providence River and Seekonk River estuary on June 12th, 2024. Rainfall totaling 1.07 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.0 meters, same as the previous survey on (June 5th). The lowest clarity this week (1.4 meters) was measured at Phillipsdale Landing, while the greatest clarity (2.5 meters) was measured at Bullock’s Reach and Conimicut Point. There was a general north-to-south gradient of increasing water clarity among the sites this week.

June 5, 2024

Water clarity was measured at seven locations in the Providence River and Seekonk River estuary on June 5th, 2024. No rainfall was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.0 meters, compared to 1.8 meters on the previous survey (May 29th). The lowest clarity this week (1.4 meters) was measured at Phillipsdale Landing and Pomham Rocks, while the greatest clarity (3.0 meters) was measured at Bullock’s Reach. There was no clear north-to-south gradient in water clarity among the sites this week.

May 29, 2024

Water clarity was measured at eight locations in the Providence River and Seekonk River estuary on May 29th, 2024. Rainfall totaling 0.37 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 1.8 meters, compared to 2.1 meters on the previous survey (May 22nd). The lowest clarity this week (1.5 meters) was measured at Edgewood Shoal, while the greatest clarity (2.1 meters) was measured at Pomham Rocks. There was no clear north-to-south gradient in water clarity among the sites this week.

March 6, 2024

Phytoplankton samples were collected on March 6, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. It was cloudy and mild on Narragansett Bay with an outgoing tide. The qualitative tow net sample had a moderate filter time, and the filtrate was a golden brown color.

The analysis of the quantitative whole water sample revealed a total of 24,820,000 cells per Liter. The micro flagellates were found at 40,000 cells/L. The most predominant phytoplankton genus was Leptocylindrus spp. at 3,840,000 cells/L. Other representative genera include Skeletonema spp. and Chaetoceros spp. Thalassionema nitzschioides (today’s featured micrograph, 200x phase contrast) is a type of phytoplankton belonging to the pennate diatom group. This photosynthetic species has small and numerous chloroplasts which give it a yellow brown color. The cells are usually found in star-shaped or in zigzagged chains. They occur in waters with salinity between 12-38 ppt and 15°C.

Week of December 10 – 16, 2023

Phytoplankton samples were collected on December 13, 2023 at Bullock’s Reach and analyzed in the laboratory shortly after collection. It was calm and brisk on Narragansett Bay with an outgoing tide. The qualitative tow net sample had a moderate filter time, and the filtrate was a light brown color with some particulate matter. The analysis of the quantitative whole water sample revealed a total of 81,000 cells per liter. The micro flagellates were found at 11,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 31,000 cells/L. Other representative genera include Leptocylindrus spp. and Guinardia spp. The photo featured this week is a 200x phase-contrast image of Staurastrum, a type of green algae in the desmid family. It gets its name from the Greek “stauron” which means cross and “astron” which means star. It is made of highly constricted unicells that are radially symmetrical and can be distinguished by cell wall patterns. Staurastrum is a food source for zooplankton in the aquatic food web.

Week of November 26 – December 2, 2023

Phytoplankton samples were collected on November 30, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. It was sunny and brisk on Narragansett Bay with calm conditions and a southwest wind at less than 10 kts. The qualitative tow net sample had a quick filter time, and the filtrate was a light tan color. The analysis of the quantitative whole water sample revealed a total of 153,000 cells per liter. The microflagellates were found at 52,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 65,000 cells/L. Other representative genera include Chaetoceros spp. and Eucampia spp. Chaetoceros socialis (see image, 200x phase contrast) is a diatomic phytoplankton found in marine and brackish waters. These phytoplankton have a characteristic linear colonial growth habit and their very long, overlapping, spines are thought to minimize sinking rates.

Week of November 13 – 19, 2023

Phytoplankton whole water sample was collected on November 15, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. No qualitative tow-net sample was collected this day. It was calm, clear, and very brisk on Narragansett Bay with clear water about 6.2 meters down. Sonde data revealed the surface water temperature was 10.4°C, salinity was 24.8 psu, and chlorophyll a was 0.8 ug/L. The analysis of the quantitative whole water sample revealed a total of 77,000 cells per Liter. The microflagellates were found at 39,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 13,000 cells/L. Other representative genera include Leptocylindrus spp., Chaetoceros spp. and Pseudo-nitzchia spp.