Historical News

Week of May 30 – June 5, 2021

Water Column Clarity

​Water clarity was measured at six locations in the Providence River estuary on June 3, 2021. Conditions were relatively dry, with only 0.12 inches of rainfall occurring in the 3 days prior to sampling. Overall, water clarity decreased by 0.5 meters from the previous survey. Secchi depth averaged 1.6 meters, compared to 2.1 meters on May 26, 2021. The lowest clarity (1.4 meters) was measured at Edgewood Yacht Club, while the greatest clarity (2.2 meters) was measured at Conimicut Point. Water clarity increased along a gradient from north to south.

Week of May 30 - June 5, 2021

Phytoplankton Sampling

Phytoplankton samples were collected on June 3, 2021 at Bullock Reach and analyzed in the laboratory shortly after collection. It was a beautiful, calm and mild day on Narragansett Bay.  Sondes data revealed the surface water temperature was 17.28°C, salinity was 15.86 psu, and chlorophyll a was 9.24 ug/L. 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. There was much detritus in the sample. 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 2,956,000 cells per Liter. The flagellates were found at 112,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 1,576,000 cells/L. Many were found in chains of 4-6 cells. Other representative genera include Eutreptiella spp., Chaetoceros spp., and centic diatoms.

200x phase contrast micrograph of Staurastrum spp. phytoplankton.Staurastrum 6.3.21.jpg

Week of June 6 - 12, 2021

R/V Monitor's Blog

​On Wednesday, June 9th, the crew of the R/V Monitor was out on the upper Bay collecting bacteria samples, taking Secchi Disk and Par sensor water clarity measurements, conducting water column profiles using the Seabird instrument, and conducting real-time surface mapping of water quality parameters, including dissolved oxygen, chlorophyll, water temperature, salinity, and pH, all in an effort to document water quality improvements associated with NBC construction projects. In addition, the Bullock's Reach buoy was serviced this day, as it was experiencing communications issues. Sara captained the boat while monitoring professionals Justin, Mike and Jeff serviced the buoy, and collected the samples and data. The day began cloudy and humid with no wind and calm waters. The sun broke through later in the morning. The featured photo was taken of the crew servicing NBC's Bullock's Reach buoy.

6-9-21 BR Buoy Service.jpg 

Week of May 23 – 29, 2021

Fixed Site Network

Phillipsdale Landing

Phillipsdale Landing sondes were changed out for routine maintenance during mid-day on May 25. Overall, water quality at this site was good this week. A total of 1.95 inches of rainfall was recorded at TF Green, with a majority (1.93 inches) occurring during the last two days of the week. Blackstone River flows were low most of the week but increased during the large rain events impacting surface and bottom salinity concentrations. Salinity at the surface averaged 14.8 ppt and ranged from 4.7 ppt to 24.7 ppt, while bottom salinity averaged 20.8 ppt and ranged from 7.1 ppt to 28.1 ppt. Surface water temperatures this week were slightly warmer than the previous week, averaging 18.6°C and ranging from 15.1°C to 24.1°C. Bottom water temperatures averaged 17.1°C and ranged from 13.0°C to 22.2°C.

Dissolved oxygen (DO) remained well above the hypoxia threshold (2.9 mg/L) this week. Surface DO averaged 9.1 mg/L, with a minimum of 6.2 mg/L, while bottom DO averaged 7.8 mg/L, with a minimum of 5.4 mg/L. In general, chlorophyll concentrations decreased from the previous week, averaging 17.0 ug/L at the surface and 19.2 ug/L at the bottom. ​Bottom chlorophyll readings following the deployment of the new sonde on May 25 were not included in this summary due to quality control issues with the chlorophyll probe. Maximum surface concentrations reached 44.1 ug/L on May 23, suggesting an increase in phytoplankton earlier in the week. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and dissolved oxygen at this location; chlorophyll readings could also be impacted by suspended matter/particulates and macroalgae.

Bullock Reach

Bullock Reach sondes will be deployed the first week of June. 


Week of May 16 – 22, 2021

Fixed Site Network

Phillipsdale Landing

Overall, water quality at Phillipsdale was good this week. In a mostly dry week, a total of 0.01​ inches of rainfall was recorded at TF Green. Blackstone River flows decreased through the week, leading to a slight increase in surface salinity. Salinity at the surface averaged 6.9 ppt and ranged from 2.6 ppt to 19.1 ppt, while bottom salinity averaged 19.5 ppt and ranged from 5.0 ppt to 28.3 ppt. Surface water temperatures this week were warmer than the previous week, averaging 18.5°C and ranging from 15.7°C to 22.0°C. Bottom water temperatures averaged 14.9°C and ranged from 11.5°C to 20.3°C.

Dissolved oxygen (DO) remained well above the hypoxia threshold (2.9 mg/L) this week. Surface DO averaged 10.1 mg/L, with a minimum of 8.0 mg/L, while bottom DO averaged 7.2 mg/L, with a minimum of 5.0 mg/L. In general, chlorophyll concentrations increased through the week, averaging 19.8 ug/L at the surface and 11.8 ug/L at the bottom. Maximum surface concentrations reached 156.0 ug/L on May 22, suggesting an increase in phytoplankton later in the week. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and dissolved oxygen at this location; chlorophyll readings could also be impacted by suspended matter/particulates and macroalgae.

Bullock Reach

Bullock Reach sondes will be deployed the first week of June. ​


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