September 11, 2024

​Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on September 11, 2024 using a Seabird Electronics profiler. In the five days leading up to the survey, 0.02 inches of precipitation were recorded at T.F. Green. Water column stratification at the sites varied from well-mixed at Edgewood Yacht Club and Point Street Bridge, to moderately stratified at Phillipsdale Landing. 

Dissolved oxygen (DO) conditions were below the hypoxia threshold (2.9 mg/L) in the lower portion of the water column at Edgewood Yacht Club, and in the middle and lower portions of the water column at Phillipsdale Landing. The highest fluorescence readings for the week were measured around 1 meter below the surface at Phillipsdale Landing.​

October 3, 2024

​Phytoplankton samples were collected on October 3, 2024 at Bullock’s Reach and analyzed in the laboratory shortly after collection. Weather conditions and Sonde data were not recorded on this day. The qualitative tow net sample had a quick filtration time. The filtrate was slightly cloudy and reddish brown with some particulates. The analysis of the quantitative whole water sample revealed a total of 1,712,000 cells/L. The microflagellates were found at 112,000 cells/L. The most predominant phytoplankton genera were Heterocapsa spp. at 1,232,000 cells/L, Prorocentrum spp. at 108,000 cells/L, and Leptocylindrus spp. at 100,000 cells/L. Chaetoceros socialis, shown here in a 100x phase contrast micrograph, is a species of diatom belonging to one of the most diverse genera of marine planktonic organisms. Due to their high growth rates, research on the use of Chaetoceros species in biotechnology is ongoing. They are currently used in commercial aquacultures and studies suggest that they have enormous potential for producing biofuel.

September 4, 2024

​Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on September 4, 2024 using a Seabird Electronics profiler. In the five days leading up to the survey, no precipitation was recorded at T.F. Green. Water column stratification at the sites varied from well-mixed at Pomham Rocks, to weakly stratified at all other profiled sites.

Dissolved oxygen (DO) conditions were below the hypoxia threshold (2.9 mg/L) in the lower portion of the water column at Phillipsdale Landing, Edgewood Yacht Club, and India Point Park. The highest fluorescence readings for the week were measured around 1 meter below the surface at Pomham Rocks. ​

September 4, 2024

​Nutrient samples were collected from seven river stations and seven bay stations on September 4th. All bay stations were sampled at the surface and bottom. In the five days prior to sampling, there was trace precipitation recorded at T.F. Green. 

Among the river stations sampled, the highest total nitrogen (TN) and total dissolved nitrogen (TDN) were observed at Blackstone River @ Stateline (TN = 1,340 ppb, TDN = 1,560 ppb). The highest dissolved inorganic nitrogen (DIN) concentration was observed at Moshassuck River @ Footbridge at Mill St. (1,158 ppb). The lowest TN and TDN were observed at Blackstone River @ Slater Mill (TN = 951 ppb, TDN = 958 ppb), while the lowest DIN was observed at Pawtuxet River @ Broad St. (665 ppb).

Among the bay stations sampled, the highest surface total nitrogen (TN), total dissolved nitrogen (TDN), and dissolved inorganic nitrogen (DIN) were observed at Pawtuxet Cove (TN = 963 ppb, TDN = 610  ppb, DIN = 368 ppb). The lowest surface TN and TDN were at Conimicut Point (TN = 456 ppb, TDN = 167 ppb, average of duplicates), while the lowest surface DIN concentrations were observed at Conimicut Point, Edgewood Yacht Club and Pomham Rocks (13 ppb, reflecting minimum detection limits).

The next scheduled sampling date is September 18, 2024.

September 4, 2024

Phytoplankton samples were collected on September 4, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. ​It was a sunny, calm and cloudless day on Narragansett Bay. Sonde data was not analyzed on this day. The qualitative tow net sample had a quick filtration time, the filtrate was slightly cloudy and golden brown with some black particulates. The analysis of the quantitative whole water sample revealed a total of 874,000 cells/L. The microflagellates were found at 94,000 cells/L. The most predominant phytoplankton genera were Skeletonema spp. at 240,000 cells/L, Leptocylindrus spp. at 224,000 cells/L, and Cylindrotheca spp. at 188,000 cells/L. Pleurosigma, shown here in a 200x phase contrast micrograph, is a widely distributed genus of elongate, biraphid diatoms which glide and rotate in brackish to marine waters. They are pelagic and either float on the tides, sink to lower levels on top of the salt layer or attach to marine organisms. These diatoms contribute to essential oxygen levels in the ocean and also serve as a food source for animal larvae and dinoflagellates.​​

August 28, 2024

​​Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on August 28, 2024 using a Seabird Electronics profiler. In the five days leading up to the survey, 1.38 inches of precipitation were recorded at T.F. Green. Water column stratification at the sites varied from well-mixed at Point Street Bridge, to moderately stratified at Phillipsdale Landing, Pomham Rocks, and India Point Park 

Dissolved oxygen (DO) conditions were below the hypoxia threshold (2.9 mg/L) in the lower portion of the water column at Pomham Rocks and India Point Park, and in all portions of the water column (upper, middle and lower) at Phillipsdale Landing. The highest fluorescence readings for the week were measured around 1 meter below the surface at India Point Park.

August 21, 2024

​Phytoplankton samples were collected on August 21, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. It was sunny and breezy on Narragansett Bay. Sonde data revealed the surface water temperature was 22.0°C, salinity was 27.1 psu, and chlorophyll a was 7.0 ug/L. The qualitative tow net sample had a quick filtration time, the filtrate was a light tan color. The analysis of the quantitative whole water sample revealed a total of 433,000 cells/L. The microflagellates were found at 35,000 cells/L. The two most predominant phytoplankton genera were Skeletonema spp. at 84,000 cells/L and Leptocylindrus spp. at 79,000 cells/L. Other representative genera include Ceratulina spp., and Cylindrotheca spp. Today’s featured 200x phase-contrast micrograph shows Chaetoceros curvisetus, a species of marine phytoplankton that is widely distributed and common to North Atlantic waters. Chaetoceros serves as an important food source within the water column and major carbon contributor to the benthic environment. Chaetoceros has been reported to contribute about 91% of total phytoplankton cells serving as an important primary producer within this area.

August 21, 2024

​Water column profiles were conducted at eight locations in the Providence and Seekonk River estuaries on August 21, 2024 using a Seabird Electronics profiler. In the five days leading up to the survey, 0.48 inches of precipitation were recorded at T.F. Green. Water column stratification at the sites varied from weakly stratified at seven of eight sites, to moderately stratified at Phillipsdale Landing. 

Dissolved oxygen (DO) conditions were below the hypoxia threshold (2.9 mg/L) in the lower portion of the water column at Edgewood Yacht Club, in the middle and lower portions of the water column at Edgewood Shoals, and in all portions of the water column (upper, middle and lower) at India Point Park. Conditions at Phillipsdale Landing did not dip below the hypoxia threshold but did approach it in the lower portion of the water column. The highest fluorescence readings for the week were measured around 1.5 meters below the surface at Bullock Reach Buoy.

July 24, 2024

Phytoplankton samples were collected on July 24, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. It was a cloudy and humid day on Narragansett Bay. Sonde data revealed the surface water temperature was 24.4°C, salinity was 26.8 psu, and chlorophyll a was 12.8 ug/L. The qualitative tow net sample had a medium filtration time and the filtrate was clear with a light brown color. Some particulates were noted in the filtrate. The analysis of the quantitative whole water sample revealed a total of 1,154,000 cells/L. The microflagellates were found at 672,000 cells/L. The most predominant phytoplankton genus was Eutreptiella spp. at 154,000 cells/L. Other representative genera include Prorocentrum spp. and Heterocapsa spp. Polykrikos spp. is a genus of marine dinoflagellates featured in today’s 200x phase contrast micrograph image. It gets its name from the Greek “poly” – many, and “krikos” – ring or circle. Polykrikos have been found to regulate algal blooms as they feed on toxic dinoflagellates. However, there is also some data available on Polykrikos being toxic to fish.​

August 14, 2024

​Water column profiles were conducted at seven locations in the Providence and Seekonk River estuaries on August 14, 2024 using a Seabird Electronics profiler. In the five days leading up to the survey, 1.32 inches of precipitation were recorded at T.F. Green. Water column stratification at the sites varied from weakly stratified at Point Street Bridge, India Point Park, Pomham Rocks and Edgewood Yacht Club, to strongly stratified at Phillipsdale Landing. 

Dissolved oxygen (DO) conditions were below the hypoxia threshold (2.9 mg/L) in the lower portion of the water column at Pomham Rocks, in the middle and lower portions of the water column at Edgewood Yacht Club, and in all portions of the water column (upper, middle and lower) at Point Street Bridge, India Point Park and Phillipsdale Landing. The highest fluorescence readings for the week were measured around 1 meter below the surface at Phillipsdale Landing.

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