Historical News

Week of May 16-22, 2021

Phytoplankton Sampling

Phytoplankton samples were collected on May 19, 2021 at Bullock's Reach and analyzed in the laboratory shortly after collection.  It was a sunny and gorgeous day on Narragansett Bay.  Sondes data revealed the surface water temperature was 16.2oC, salinity was 22.0 psu, and chlorophyll a was 2.6 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a thick golden brown color and had a quick filter time. The tow net sample was analyzed qualitatively for microorganisms using 100x 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 5,580,000 cells per Liter.  The flagellates were found at 69,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 4,536,000 cells/L. Many were found in chains of 6-8 cells. Other representative genera include Chaetoceros spp., Thalassiosira spp., and pennate diatoms.

 

100x phase contrast image of the tow net phytoplankton

 tow net phytoplankton 5.19.21.jpg

Week of March 21 – 27, 2021

Nutrients Sampling

​Nutrient samples were collected from fourteen local and border river stations and eight Bay stations on March 24, 2021; all Bay stations were sampled at the surface with Edgewood Shoal also sampled at the bottom. Weather conditions leading up to the sampling day were mostly dry, with only 0.02 inches of recorded rainfall in the five days prior to sampling.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were all observed at Ten Mile River at Central Avenue. At this site, concentrations for TN, TDN, and DIN were 2,400 ppb, 2,660 ppb, and 2,142.7 ppb, respectively. The lowest TN (519 ppb) and TDN (551 ppb) was observed at Moshassuck River at Higginson Avenue, while the lowest DIN (140 ppb) were observed at Coles River at Milford Avenue.

Among the Bay stations sampled, the highest surface nitrogen concentrations were observed at Phillipsdale Landing. At this site, TN, TDN, and DIN concentrations were 1,220 ppb, 1,140 ppb, and 896.7 ppb, respectively. The lowest surface TN (690 ppb), and TDN (364 ppb) were observed at Bullock Reach Buoy, while lowest DIN (195 ppb) was observed at Conimicut Point.  Chlorophyll-a concentrations at the Bay sites higher than the previous sampling event, averaging 11.81 ug/L across all sites. The maximum result of 29.33 ug/L was recorded at Bullock Reach Buoy site.

Results from nutrient sampling on April 7 are pending analysis. The next scheduled sampling date is April 21. ​


Week of March 7 – 13, 2021

Nutrients Sampling

​Nutrient samples were collected from fourteen local and border river stations and seven bay stations on March 10, 2021; the Bay stations were sampled at the surface and bottom. Weather conditions leading up to the sampling day were dry, with no recorded rainfall in the five days prior to sampling.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were all observed at Ten Mile River at Central Avenue. At this site, concentrations for TN, TDN, and DIN were 3,340 ppb, 3,560 ppb, and 3,007 ppb, respectively. The lowest TN (580 ppb), TDN (578 ppb), and DIN (223 ppb) were observed at Coles River at Milford Road.

Among the Bay stations sampled, the highest surface nitrogen concentrations were observed at Pomham Rocks. At this site, TN, TDN, and DIN concentrations were 1,720 ppb, 1,480 ppb, and 1,372 ppb, respectively. The lowest surface TN (549 ppb), TDN (405 ppb), and DIN (268.2 ppb) were all observed at Bullock Reach Buoy. Chlorophyll-a concentrations at the Bay sites remain low, averaging 2.63 ug/L across all sites. The maximum result of 5.83 ug/L was recorded at Phillipsdale Landing.

Results from nutrient sampling on March 24 are pending analysis. The next scheduled sampling date is April 7. ​


Week of February 21 – 27, 2021

Nutrients Sampling

​Nutrient samples were collected from seven local river stations and five bay stations on February 24, 2021; the Bay stations were sampled at the surface and bottom. Due to a boat malfunction three scheduled bay stations (India Point Park, Edgewood Shoal, and Pawtuxet Cove) were not sampled this week. Weather conditions leading up to the sampling day were mostly wet, with 0.81 inches of recorded rainfall and 3.5 inches of recorded snowfall in the five days prior to sampling.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were all observed at Ten Mile River at Roger Williams Avenue. At this site, concentrations for TN, TDN, and DIN were 2,090 ppb, 2,180 ppb, and 1,777 ppb, respectively. The lowest TN (766 ppb), and TDN (873 ppb) were observed at Moshassuck River at Higginson Avenue, while the lowest DIN (533.9 ppb) was observed at the Warren Reservoir station.

Among the Bay stations sampled, the highest surface nitrogen concentrations were observed at Phillipsdale Landing. At this site, TN, TDN, and DIN concentrations were 1,260 ppb, 1,230 ppb, and 972.9 ppb, respectively. The lowest surface TN (513 ppb) was observed at Conimicut Point, while the lowest TDN (489 ppb) and DIN (322.5 ppb) were observed at Bullock Reach Buoy. Chlorophyll-a concentrations at the Bay sites remain low, averaging 1.44 ug/L across all sites. The maximum result of 1.78 ug/L was recorded at Pomham Rocks.

Results from nutrient sampling on March 10 are pending analysis. The next scheduled sampling date is March 24.  ​


Week of February 7 – 13, 2021

Nutrients Sampling

​Nutrient samples were collected from twelve local and border river stations on February 10, 2021. Due to adverse weather concerns, bay nutrient sampling was not collected as scheduled. Weather conditions leading up to the sampling day were mostly wet, with 0.54 inches of recorded rainfall and 8.3 inches of recorded snowfall in the five days prior to sampling.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were all observed at Ten Mile River at Central Avenue. At this site, concentrations for TN, TDN, and DIN were 3,940 ppb, 4,120 ppb, and 3,627 ppb, respectively. The lowest TN (850 ppb – average of duplicates) and TDN (823.5 ppb – average of duplicates) were observed at Coles River at Milford Road, while lowest DIN (494.5 ppb) was observed at Palmer River at Route 6.

Results from nutrient sampling on February 24 are pending analysis. The next scheduled sampling date is March 10. ​


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