News – Page 18 – Narrabay

July 10, 2024

Phytoplankton samples were collected on July 10, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. Sonde data revealed the surface water temperature was 25.9°C, salinity was 23.6 psu, and chlorophyll a was 5.0 ug/L. The qualitative tow net sample had a short filtration time, the filtrate was slightly cloudy, and the analyzed sample volume was 500 mL. The analysis of the quantitative whole water sample revealed a total of 999,000 cells/500 mL. The most predominant phytoplankton genus was Skeletonema spp. at 572,000 cells/500mL. Other representative genera include Chaetoceros spp. and Leptocylindrus spp. Ditylum is a genus of marine centric diatoms with a worldwide distribution in boreal, tropical, coastal and estuarine environments and is the feature 200x phase contrast micrograph image for the day. Ditylum spp. have been used as a model organism for genetic studies concerning metapopulation structures and environmental influence on population genetic variability.

August 21, 2024

Nutrient samples were collected from ten river stations and eight bay stations on August 7th. 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 0.59 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 Blackstone River @ Stateline (TN = 1,250 ppb, TDN = 1,80 ppb, DIN = 970 ppb). The lowest TN was observed at Runnins River @ River Rd (743 ppb), while the lowest TDN and DIN were observed at Palmer River @ Rt 6 (TDN = 360 ppb, DIN = 13 ppb, average of duplicates).

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 = 1,110 ppb, TDN = 944 ppb, DIN = 683 ppb, average of duplicates). The lowest surface TN was at Conimicut Point (549 ppb), while the lowest surface TDN and DIN concentrations were observed at Bullock Reach Buoy (TDN = 322 ppb, DIN = 132 ppb).

The next scheduled sampling date is September 4, 2024.

October 30, 2024

Surface chlorophyll data were collected on October 30, 2024 while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuary. The average chlorophyll concentrations were categorized as good in all areas surveyed. Overall, chlorophyll ranged from 0.48 µg/L to 12.03 µg/L with an average of 2.11 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

October 23, 2024

Surface chlorophyll data were collected on October 23, 2024 while the R/V Monitor was underway collecting nutrient samples in the Providence River estuary. The average chlorophyll concentrations were categorized as good in all areas surveyed. Overall, chlorophyll ranged from 0.78 µg/L to 5.11 µg/L with an average of 2.96 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

October 17, 2024

Surface chlorophyll data were collected on October 17, 2024 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 all areas surveyed. Overall, chlorophyll ranged from 1.23 µg/L to 11.31 µg/L with an average of 3.05 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

June 12, 2024

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.

September 25, 2024

Surface chlorophyll data were collected on September 25, 2024 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 Northern Providence River Channel and Edgewood, and as fair in all other areas. Overall, chlorophyll ranged 0.99 to 15.81 µg/L with an average of 5.14 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

September 11, 2024

Surface chlorophyll data were collected on September 11, 2024 while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuaries. The average chlorophyll concentrations were categorized as fair in all areas. Overall, chlorophyll ranged 2.45 to 33.57 µg/L with an average of 11.07 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

August 21, 2024

Surface chlorophyll data were collected on August 21, 2024 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 Seekonk River and Northern Providence River Channel, and as fair in all other areas. Overall, chlorophyll ranged 0.93 to 20.56 µg/L with an average of 4.42 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.

August 14, 2024

Surface chlorophyll data were collected on August 14, 2024 while the R/V Monitor was underway collecting nutrient samples in the Providence and Seekonk River estuaries. The average chlorophyll concentrations were categorized as poor in the Seekonk River, and as fair in all other areas. Overall, chlorophyll ranged 1.31 to 109.86 µg/L with an average of 19.45 µg/L. The chlorophyll concentrations from this date are presented in the map below using Inverse Distance Weighting (IDW) interpolation.