Historical News
Week of August 20 - 26, 2023
Water Column Clarity
Water clarity was measured at four locations in the Providence River estuary on August 23rd, 2023. Rainfall totaling 2.16 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 1.7 meters, compared to 2.8 meters on the previous survey (August 18th). The lowest clarity this week (1.3 meters) was measured at Pawtuxet Cove, while the greatest clarity (2.0 meters) was measured at Edgewood Yacht Club. There was no clear north-to-south gradient in water clarity among the sites this week.
Week of November 12 – 18, 2023
Fixed Site Network
Phillipsdale Landing
Overall, water quality was good at Phillipsdale Landing this week. There were 0.16 inches of precipitation recorded at T.F. Green this week and Blackstone River flow was slightly higher than normal for this time of year. Surface salinity averaged 13.7 ppt and ranged from 3.7 ppt to 22.6 ppt. Bottom salinity averaged 22.9 ppt and ranged from 11.8 ppt to 28.3 ppt. Temperatures were slightly lower than last week, averaging 10.4°C at the surface and ranging from 7.9°C to 12.4°C. At the bottom, temperatures averaged 12.4°C and ranged from 10.5°C to 14.0°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 8.9 mg/L and ranging from 6.7 to 11.0 mg/L. Bottom DO averaged 6.8 mg/L and ranged from 5.4 mg/L to 8.8 mg/L. Chlorophyll readings remained low, averaging 0.6 ug/L at the surface and 1.3 ug/L at the bottom. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location.
Bullock Reach
The sondes at Bullock Reach were retrieved on the morning of November 14th for the 2023 season. For the two and half days of data this week before retrieval, water quality was good. Salinity averaged 25.7 ppt, 27.9 ppt, and 29.8 ppt at the surface, middle, and bottom sondes, respectively. Surface salinity ranged 23.5 – 27.9 ppt, mid salinity ranged 25.1 – 29.7 ppt, and bottom salinity ranged 29.0 – 30.4 ppt. Surface temperatures averaged 11.4°C and ranged from 10.2°C to 12.4°C. Mid temperatures averaged 12.4°C and ranged from 11.3°C to 13.2°C. Bottom temperatures averaged 13.2°C and ranged from 12.5°C to 13.7°C.
DO concentrations at Bullock Reach remained above the hypoxia threshold all week. Surface DO averaged 8.0 mg/L and ranged 7.4 – 8.8 mg/L. In the mid waters, DO averaged 7.5 mg/L and ranged 7.1 – 8.1 mg/L. At the bottom, DO averaged 7.1 mg/L and ranged 6.7 – 7.5 mg/L. Chlorophyll concentrations were low, averaging 1.2 ug/L, 1.9 ug/L, and 1.3 ug/L at the surface, mid, and bottom waters, respectively.
Week of November 26 - December 2, 2023
Phytoplankton Sampling
Phytoplankton samples were collected on November 30, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. It was sunny and brisk on Narragansett Bay with calm conditions and a southwest wind at less than 10 kts. The qualitative tow net sample had a quick filter time, and the filtrate was a light tan color. The analysis of the quantitative whole water sample revealed a total of 153,000 cells per liter. The microflagellates were found at 52,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 65,000 cells/L. Other representative genera include Chaetoceros spp. and Eucampia spp. Chaetoceros socialis (see image, 200x phase contrast) is a diatomic phytoplankton found in marine and brackish waters. These phytoplankton have a characteristic linear colonial growth habit and their very long, overlapping, spines are thought to minimize sinking rates.
Week of November 13 - 19, 2023
Phytoplankton Sampling
Phytoplankton whole water sample was collected on November 15, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. No qualitative tow-net sample was collected this day. It was calm, clear, and very brisk on Narragansett Bay with clear water about 6.2 meters down. Sonde data revealed the surface water temperature was 10.4°C, salinity was 24.8 psu, and chlorophyll a was 0.8 ug/L. The analysis of the quantitative whole water sample revealed a total of 77,000 cells per Liter. The microflagellates were found at 39,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 13,000 cells/L. Other representative genera include Leptocylindrus spp., Chaetoceros spp. and Pseudo-nitzchia spp.
Week of October 29 - November 4, 2023
Phytoplankton Sampling
Phytoplankton samples were collected on November 1, 2023 at Bullock Reach and analyzed in the laboratory shortly after collection. It was cloudy and brisk on Narragansett Bay with a northwest wind at 10 kts. Sonde data revealed the surface water temperature was 13.08°C, salinity was 22.63 psu, and chlorophyll a was 1.06
ug/L. The qualitative tow net sample had a moderate filter time, and the filtrate was a light yellow-brown color. The analysis of the quantitative whole water sample revealed a total of 119,000 cells per liter. The micro flagellates were found at 62,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 46,000 cells/L. Other representative genera include Leptocylindrus spp., Eucampia spp., and Prorocentrum spp. Prorocentrum micans (see image, 200x phase contrast) is a tear-dropped shaped dinoflagellate that is often found in Narragansett Bay during the late summer-autumn time period. This species can form extensive blooms but is considered harmless.
