Week of November 13 – 19, 2023

Nutrient samples were collected from 14 river stations and 8 bay stations on November 15th. Edgewood Shoal was sampled at the surface and bottom; all other bay stations were sampled at the surface only. In the five days prior to sampling, there were 0.01 inches of precipitation 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 = 2,320 ppb, TDN = 2,470 ppb, DIN = 2,170 ppb). The lowest TN was observed at Moshassuck River @ Higginsin Ave, the lowest TDN was at Palmer River @ Rt. 6 (455 ppb), and the lowest DIN was observed in one of the duplicate samples at Coles River @ Milford Rd. (198 ppb).

Among the bay stations sampled, the highest surface TN, TDN, and DIN were observed at Pawtuxet Cove (TN = 1,110 ppb, TDN = 1,150 ppb, DIN = 908 ppb). The lowest surface TN, TDN, and DIN were observed at Bullock Reach Buoy (TN = 477 ppb, TDN = 419 ppb, DIN = 233 ppb). Chlorophyll a concentrations at the surface bay stations were low this week; concentrations averaged 0.73 μg/L overall with a maximum of 1.11 μg/L at Pawtuxet Cove.

The next scheduled sampling date is November 29, 2023.​

November 5-11, 2023

Phillipsdale Landing

Overall, water quality was good at Phillipsdale Landing this week. Sondes were swapped this week on the morning of November 7th. There were 0.18 inches of precipitation recorded at T.F. Green this week. Blackstone River flow was higher than normal for this time of year. Surface salinity averaged 5.9 ppt and ranged from 2.0 ppt to 19.3 ppt. Bottom salinity averaged 21.1 ppt and ranged from 4.6 ppt to 28.3 ppt. Temperatures decreased this week, averaging 10.6°C at the surface and ranging from 8.1°C to 12.6°C. At the bottom, temperatures averaged 13.5°C and ranged from 10.5°C to 15.3°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold of 2.9 mg/L at both the surface and bottom all week. Surface DO remained similar to the previous week, averaging 9.8 mg/L and ranging from 7.2 to 10.8 mg/L. Bottom DO averaged 5.9 mg/L and ranged from 4.0 mg/L to 10.0 mg/L. Chlorophyll readings remained low, averaging 0.6 ug/L at the surface and 0.9 ug/L at the bottom. Maximum chlorophyll at the surface was only 1.0 ug/L. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. 

Bullock Reach

Overall, water quality was good at Bullock Reach this week. Salinity averaged 24.4 ppt, 27.5 ppt, and 29.7 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 18.5 – 27.2 ppt, mid salinity ranged 24.0 – 29.9 ppt, and bottom salinity ranged 28.2 – 30.7 ppt. Surface temperatures averaged 12.8°C and ranged from 10.7°C to 14.1°C. Mid temperatures averaged 13.4°C and ranged from 12.3°C to 14.3°C. Bottom temperatures averaged 14.2°C and ranged from 13.3°C to 14.8°C.

DO concentrations at Bullock Reach remained above the hypoxia threshold all week. Surface DO averaged 7.8 mg/L and ranged 6.8 – 9.5 mg/L. In the mid waters, DO averaged 7.3 mg/L and ranged 6.3 – 8.0 mg/L. At the bottom, DO averaged 6.7 mg/L and ranged 5.6 – 7.3 mg/L.  Chlorophyll concentrations were low, averaging 2.0 ug/L, 2.5 ug/L, and 2.1 ug/L at the surface, mid, and bottom waters, respectively. The maximum surface chlorophyll of 5.0 ug/L occurred during the afternoon on November 5th.​

October 29-November 5, 2023

Phillipsdale Landing

Overall, water quality was good at Phillipsdale Landing this week. There were 1.14 inches of precipitation recorded at T.F. Green this week, mostly from rain events on the 29th and 30th. Blackstone River flow was higher than normal for this time of year. Surface salinity averaged 8.7 ppt and ranged from 2.0 ppt to 21.8 ppt. Bottom salinity averaged 20.5 ppt and ranged from 6.1 ppt to 27.9 ppt. Temperatures decreased this week, averaging 13.0°C at the surface and ranging from 8.8°C to 16.5°C. At the bottom, temperatures averaged 15.0°C and ranged from 11.2°C to 16.7°C.

Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold of 2.9 mg/L at both the surface and bottom. Surface DO remained similar to the previous week, averaging 8.7 mg/L and ranging from 5.6 to 11.1 mg/L. Bottom DO averaged 5.9 mg/L and ranged from 4.6 mg/L to 10.0 mg/L. Chlorophyll readings remained low, averaging 0.9 ug/L at the surface and 0.8 ug/L at the bottom. Maximum chlorophyll at the surface was only 3.5 ug/L, recorded on the morning of October 29th. . Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. 

Bullock Reach 

Sondes were swapped this week on the morning of October 31. Overall, water quality was good at Bullock Reach this week. Salinity averaged 23.9 ppt, 27.3 ppt, and 29.4 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 20.4 – 27.5 ppt, mid salinity ranged 23.0 – 29.3 ppt, and bottom salinity ranged 27.8 – 30.4 ppt. Surface temperature averaged 14.3°C and ranged from 11.6°C to 17.0°C. Mid temperatures averaged 15.2°C and ranged from 13.6°C to 16.8°C. Bottom temperatures averaged 15.6°C and ranged from 13.9°C to 16.2°C.

DO concentrations at Bullock Reach remained above the hypoxia threshold all week. Surface DO averaged 7.3 mg/L and ranged 6.2 – 8.9 mg/L. In the mid waters, DO averaged 6.8 mg/L and ranged 5.8 – 9.5 mg/L. At the bottom, DO averaged 6.5 mg/L and ranged 5.9 – 7.2 mg/L.  Chlorophyll concentrations were low, averaging 1.9 ug/L, 2.5 ug/L, and 1.6 ug/L at the surface, mid, and bottom waters, respectively. The maximum surface chlorophyll of 4.7 ug/L occurred during the afternoon on November 4th.​

October 29-November 4, 2023

The R/V Monitor has been retired since the last blog update for the week of February 19-25, 2023.  However, the Narragansett Bay Commission is excited to announce its new monitoring vessel, Data Stream.  The Data Stream is a brand new 2023 Parker 23290 SL: Sport cabin boat.  The Data Stream is equipped with state-of-the-art electronics, including the latest Garmin GPS with Radar overlay capability, a remote-control spotlight, and salt and freshwater wash down. Data Stream’s Yamaha engine is a 300hp electronic shift engine which is an upgrade from the 250 HP Mercury on the Monitor.

The Data Stream picked up where the Monitor left off monitoring water quality in the upper Narragansett Bay.  Throughout the Spring and Summer, the crew of the Data Stream was out on the upper Bay collecting bacteria, nutrients and plankton samples, taking Secchi Disk 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.  In addition, the fixed site monitoring stations were deployed and continuously maintained. The featured photo shows the new monitoring vessel, Data Stream.

October 2023

​Phillipsdale Landing

The Phillipsdale Landing sondes have been deployed for the season since May 9th, 2023 utilizing a new setup allowing staff access to the equipment from the boat instead of standing on the dock. During the month of October, sondes were changed out for routine maintenance on October 10th and 24th. 

Surface DO remained above the hypoxia threshold all month. The bottom waters were hypoxic periodically throughout the month, with the longest sustained hypoxic periods (8 hours) occurring in the early morning of October 14th. DO averaged 8.4 mg/L at the surface with a minimum of 4.9 mg/L, while bottom waters averaged 5.5 mg/L with a minimum of 2.3 mg/L. 

Chlorophyll readings were relatively low all month with a couple of moderately elevated readings in the bottom waters. The surface and bottom readings averaged 1.1 µg/L and 1.5 µg/L, respectively. 

Bullock Reach

The Bullock Reach buoy was deployed June 1st for the 2023 season. During the month of October, sondes were changed out for routine maintenance on October 3rd, 17th, and 31st. 

DO remained above the hypoxia threshold all month at the surface, middle, and bottom and averaged 7.7 mg/L, 6.7 mg/L, and 5.8 mg/L, respectively.

Chlorophyll readings ranged from low to elevated, with evidence of moderate phytoplankton blooms occurring throughout the month and some highly elevated (>200 ug/L) chlorophyll levels at the middle sonde throughout the day on October 16th. Readings averaged 6.5 µg/L at the surface, 18.3 µg/L at mid-depth, and 3.1 µg/L at the bottom. 

Please note that data from the Bullock Reach Surface sonde were not available between 11:15am on October 21st and 9:15 am on October 24th due to an equipment issue.

Week of October 30 – November 5, 2023

Nutrient samples were collected from 7 river stations and 8 bay stations on November 1st. Bullock Reach Buoy was sampled at the surface and bottom; all other bay stations were sampled at the surface only. In the five days prior to sampling, there were 1.14 inches of precipitation recorded at T.F. Green. 

Among the river stations sampled, the highest total nitrogen (TN) concentration was observed at Blackstone River @ Bikepath Bridge (923 ppb).  The highest total dissolved nitrogen (TDN) and dissolved inorganic nitrogen (DIN) concentrations were observed at Pawtuxet River @ Broad St. (TDN = 957 ppb, DIN = 615 ppb, average of duplicates.) The lowest TN, TDN, and DIN were observed at Woonasquatucket River @ Manton Ave Bridge (TN = 560 ppb, TDN = 613 ppb, DIN = 352 ppb).

Among the bay stations sampled, the highest surface TN was observed at Phillipsdale Landing (972 ppb); the highest surface TDN and DIN were observed at Pawtuxet Cove (TDN = 1,030 ppb, DIN = 528 ppb). The lowest surface TN, TDN, and DIN were at Conimicut Point (TN = 559 ppb, TDN = 641 ppb, DIN = 227 ppb). Chlorophyll a concentrations at the surface bay stations were low this week; concentrations averaged 1.08 μg/L overall with a maximum of 1.88 μg/L at Pomham Rocks.

The next scheduled sampling date is November 15, 2023.

October 22-28, 2023

​Surface chlorophyll data were collected on October 25, 2023 while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuaries.  The average chlorophyll concentrations were categorized Good in the areas surveyed. Overall, chlorophyll ranged from 0.91 µg/L to 4.06 µg/L with an average of 1.73 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation. 

October 15-21, 2023

Surface chlorophyll data were collected on October 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 Good in the areas surveyed. Overall, chlorophyll ranged from 0.99 µg/L to 34.57 µg/L with an average of 5.52µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

October 15-21, 2023

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.

 

Week of October 15 – October 21, 2023

​Nutrient samples were collected from 14 river stations and 8 bay stations on October 18th. Edgewood Shoal was sampled at the surface and bottom; all other bay stations were sampled at the surface only. In the five days prior to sampling, there was only traces 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 = 1,535 ppb, TDN = 1,640 ppb, DIN = 1,262 ppb, all averaged with duplicates). The lowest TN and TDN were observed at Moshassuck River @ Higginson Ave. (TN = 524 ppb, TDN = 586 ppb), while the lowest DIN was at Palmer River @ Rt. 6. (DIN = 110 ppb).

Among the bay stations sampled, the highest surface TN and TDN were observed at Phillipsdale Landing (TN = 1,150 ppb, TDN = 1,160 ppb), while the highest surface DIN was observed at Pawtuxet Cove (DIN = 689.5 ppb, average of duplicates). The lowest surface TN and TDN were observed at Conimicut Point (TN = 609 ppb, TDN = 606 ppb), while the lowest surface DIN was at Bullock Reach Buoy (DIN = 202.6 ppb). Chlorophyll a concentrations at the surface bay stations averaged 3.88 μg/L overall with a maximum of 7.75 μg/L at the India Point Park.

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