Historical News

July 3, 2024

Surface Mapping

​Surface chlorophyll data were collected on July 3, 2024 while the R/V Monitor was underway collecting bacteria samples in the Providence and Seekonk River estuaries. The average chlorophyll concentrations were categorized as poor in the Lower Providence River Area and as fair in all other areas. Overall, chlorophyll ranged from 2.27 to 52.87 µg/L with an average of 16.49 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

Dataflow 2024-07-03.jpg

Week of October 15 - October 21, 2023

Nutrients Sampling

​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.

Week of October 1 - 7, 2023

Nutrients Sampling

​Nutrient samples were collected from seven river stations and seven bay stations on October 4th. All bay stations were sampled at the surface and bottom. In the five days prior to sampling, there was 1.27 inches of rainfall recorded at T.F. Green.

Among the river stations sampled, the highest total nitrogen (TN), total dissolved nitrogen (TDN), an dissolved inorganic nitrogen (DIN) concentrations were observed at Moshassuck River @ Footbridge at Mill St. (TN=787 ppb, TDN = 873 ppb, DIN = 571.4 ppb). The lowest TN, TDN, DIN were observed at Moshassuck River @ Higginson Ave. (TN = 627 ppb, TDN = 614 ppb, DIN = 382.6 ppb).

Among the bay stations sampled, the highest surface TN, TDN, and DIN were observed at Phillipsdale Landing (TN = 1,060, TDN = 1,030 ppb, DIN = 596.4 ppb).The lowest surface concentrations were observed at Edgewood Yacht Club for TN (TN = 701.5 ppb, average of duplicates), at the Bullock Reach Buoy for TDN (TDN = 727 ppb), and at Conimicut Point for DIN (DIN = 312.3 ppb). Chlorophyll a concentrations at the surface bay stations averaged 1.32 μg/L overall with a maximum of 2.93 μg/L at the Bullock Reach Buoy.

June 12, 2024

Phytoplankton Sampling

​Phytoplankton samples were collected on June 12, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. Sonde data revealed the surface water temperature was 19.68°C, salinity was 24.22 psu, and chlorophyll a was 9.89 ug/L. The qualitative tow net sample had a short filtration time, and the filtrate was mostly clear. The analysis of the quantitative whole water sample revealed a total of 12,732,000 cells per Liter. The most predominant phytoplankton genus was Skeletonema spp. at 12,408,000 cells/L. Other representative genera include Chaetoceros spp. and Leptocylindrus spp. Prorocentrum spp. (see 200x phase contrast image below) is a dinoflagellate genus containing several toxic and harmful species. P. micans is one of the most common species in the genus. Prorocentrum is found in cold, temperate to tropical waters. This genus forms extensive red tides in many parts of the world, though blooms are usually harmless. It may excrete substances that inhibit diatom growth, but these substances do not enter the food chain or affect organisms at higher trophic levels.

2024_06_12_Prorocentrum_200xPC.JPG

May 29, 2024

Phytoplankton Sampling

​Phytoplankton samples were collected on May 29, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection.
Sonde data revealed the surface water temperature was 20.1°C,  salinity was 15.49 psu, and chlorophyll a was 12.1 ug/L.
The qualitative tow net sample had a moderate filtration time, and the filtrate was a dark tan/brown color and had particulate matter.
The analysis of the quantitative whole water sample revealed a total of 7,565,000 cells per Liter. The most predominant phytoplankton genus was Skeletonema spp. at 7,276,000 cells/L. Other representative genera include Chaetoceros spp. and Leptocylindrus spp. Chaetoceros spp. (see 200x phase contrast image below) is a genus of diatoms found in Narragansett Bay and is one of the most common and most diverse genera of marine planktonic diatoms with over 200 accepted species. Due to its high growth rates, research has been conducted into potential uses of Chaetoceros in biotechnology.

2024_05_29_Chaetoceros_200xPC.JPG

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