Jamie Samons

May 21-27, 2023

Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on May 24, 2023 using a Seabird Electronics profiler. In the three days leading up to the survey, there were 0.02 inches of precipitation recorded at T.F. Green. Despite the lack of recent rainfall, all sites exhibited strong density stratification except for Point St Bridge, which exhibited moderate density stratification.

Dissolved oxygen (DO) conditions remained above the hypoxia threshold (2.9 mg/L) at all sites this week; the lowest DO observed was approximately 4.56 mg/L in the bottom waters of Phillipsdale landing. Fluorescence was low to moderately elevated this week, with the highest value (25.3 mg/m3) observed at Pomham Rocks.

May 21-27, 2023

​Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was fair to good this week. Weather conditions were dry this week, with only a very light rain of 0.02 inches recorded at T.F. Green. Blackstone River flow started the week off with a high flow rate due to the May 20th storm, but then decreased over the course of the week. Surface salinity remained well below bottom salinity. Surface salinity this week averaged 13.2 ppt and ranged from 6.5 ppt to 24.5 ppt. At the bottom, salinity averaged 22.5 ppt and ranged from 9.6 ppt to 28.6 ppt. Salinity at the surface averaged 5.2 ppt and ranged from 1.9 ppt to 8.9 ppt. At the bottom, salinity averaged 15.8 ppt and ranged from 3.2 ppt to 27.8 ppt. Temperatures this week averaged 18.3°C at the surface and 16.3 °C at the bottom. Surface temperatures ranged from 15.3°C to 22.0°C, while bottom temperatures ranged from 14.0°C to 19.5°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold of 2.9 mg/L at the surface. DO dropped below the hypoxia threshold at the bottom only briefly on the morning of May 26th. Surface DO remained similar to the previous week, averaging 8.3 mg/L and ranging 6.9-10.0 mg/L. Bottom water DO concentration averaged 5.6 mg/L and ranged from 2.0 mg/L to 8.6 mg/L. Chlorophyll concentrations decreased from the previous week, averaging 2.8 ug/L at the surface and 13.1 ug/L at the bottom. Maximum surface chlorophyll readings reached 34.5 ug/L, recorded in the morning of March 23rd. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. Also, please note that isolated portions of chlorophyll data from the surface sonde on May 23rd and from the bottom sonde on May 27th were excluded from the summary this week due to suspected interference.

Bullock Reach 

Bullock Reach sondes will be deployed later this spring for the 2023 monitoring season. 

May 14-20, 2023

​Surface chlorophyll data were collected on May 18, 2023 while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuaries. The average chlorophyll concentrations were categorized as good in the areas surveyed. Overall, chlorophyll ranged between 1.79 and 7.20 µg/L with an average of 3.29 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

May 14-20, 2023

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on May 18. There was no precipitation recorded at TF Green in the five days prior to the survey. Secchi depth averaged 2.0 meters, compared to 1.9 meters on the previous survey (May 10). The lowest clarity this week (1.4 meters) was measured at Pawtuxet Cove while the greatest clarity (2.6 meters) was measured at Phillipsdale Landing and India Point Park. There was no clear north-to-south gradient in water clarity among the sites this week.​

May 14-20, 2023

​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.

May 14-20, 2023

Nutrient samples were collected from seven river stations on May 17th and seven bay stations on May 18th. All bay stations were sampled at the surface and bottom. In the five days prior to sampling, there were 0.01 inches of rainfall recorded at T.F. Green. 

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) concentrations were observed at Ten Mile River @ Central Ave. (TN = 1,360 ppb, TDN = 1,310 ppb, DIN = 1,080 ppb). The lowest TN, TDN, and DIN concentrations were observed at Woonasquatucket River @ Manton Ave. Bridge (TN and TDN = 743 ppb, DIN = 538 ppb, average of duplicates).

Among the bay stations sampled, the highest surface TN, TDN, and DIN concentrations were observed at Pawtuxet Cove (TN = 1,110 ppb, TDN = 1,010 ppb, DIN = 778 ppb). The lowest surface TN and DIN concentrations were observed at Conimicut Point (TN = 439 ppb, DIN = 13.0 ppb), while the lowest surface TDN concentration was observed at Bullock Reach Buoy (149 ppb, average of duplicates). Chlorophyll a concentrations at the surface bay stations were relatively low, averaging 9.61 μg/L across all sites with a maximum of 14.0 μg/L (average of duplicates) at Bullock Reach Buoy.

The next scheduled sampling date is May 31, 2023.

May 14-20, 2023

Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on May 18, 2023 using a Seabird Electronics profiler. There was no precipitation recorded at T.F. Green in the three days leading up to the survey. Despite the lack of recent rainfall, Phillipsdale Landing still showed strong density stratification and Bullock Reach Buoy showed moderate density stratification; all other sites were well mixed to weakly stratified.

Dissolved oxygen (DO) conditions remained above the hypoxia threshold (2.9 mg/L) at all sites this week; the lowest DO observed was approximately 6.62 mg/L near the middle of the water column at Pomham Rocks. Fluorescence was low to moderately elevated, with the highest value (10.09 mg/m3) observed 2.5 m deep at Conimicut Point West.

May 14-20, 2023

​Phillipsdale Landing

Overall, water quality at Phillipsdale Landing was fair to good this week. Weather conditions were wet this week, with a total of 3.02 inches on March 20th, recorded at T.F. Green. Blackstone River flow declined over the course of the week only to increase at the end with the March 20th storm. Surface salinity remained well below bottom salinity. Surface salinity this week averaged 13.2 ppt and ranged from 6.5 ppt to 24.5 ppt. At the bottom, salinity averaged 22.5 ppt and ranged from 9.6 ppt to 28.6 ppt. Temperatures increased this week, averaging 16.6°C at the surface and 15.0 at the bottom. Surface temperatures ranged from 13.8°C to 20.0°C, while bottom temperatures ranged from 12.6°C to 17.8°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold of 2.9 mg/L at the surface. DO dropped below the hypoxia threshold at the bottom for a few hours on the night of May 17th. Surface DO averaged 9.1 mg/L and ranged 6.7 – 11.4 mg/L. Bottom DO concentrations averaged 6.2 mg/L and ranged from 0.5 mg/L to 10.5 mg/L. Chlorophyll readings rose from the previous week, averaging 12.9 ug/L at the surface and 26.2 ug/L at the bottom. Maximum chlorophyll at the surface reached 107.5 ug/L on May 15th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. Also, please note that portions of chlorophyll data from the surface and bottom sondes from May 14th – 20th are not included in the summary above due potential fouling interference which is common at this site.

Bullock Reach 

Bullock Reach sondes will be deployed later this spring for the 2023 monitoring season.

May 7-13, 2023

​Surface chlorophyll data were collected on May 10, 2023 while the R/V Monitor was underway collecting bacteria samples in the Providence and Seekonk River estuaries. The average chlorophyll concentrations were categorized as good in the areas surveyed. Overall, chlorophyll ranged between 0.66 and 6.74 µg/L with an average of 1.61 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

May 7-13, 2023

Water clarity was measured at seven locations in the Providence River and Seekonk River estuaries on May 10. Rainfall totaling 0.17 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 1.9 meters, compared to 1.4 meters on the previous survey (May 3). The lowest clarity this week (1.5 meters) was measured at Bullock Reach while the greatest clarity (2.1 meters) was measured at Conimicut Point, India Point Park, and Point St. Bridge. There was a general north-to-south gradient of decreasing water clarity among the sites this week.​

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