Phytoplankton samples were collected on May 1, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. It was a cold and breeze day on Narragansett Bay with cloudy conditions. The qualitative tow net sample had a long filtration time, and the filtrate was a reddish brown and slightly cloudy.
The analysis of the quantitative whole water sample revealed a total of 4,006,000 cells per Liter. The micro flagellates were found at 24,000 cells/L. The most predominant phytoplankton genus was Skeletonema spp. at 1,646,000 cells/L. Other representative genera include Thalassiosira spp., Leptocylindrus spp., and Chaetoceros spp. This week’s featured image is Eucampia spp. (200x phase contrast), a type of diatomic phytoplankton that is often found in the North Atlantic Ocean. This genus is often found in a curved form and in helical chains. This diatom is yellow-brown in color with numerous green chloroplasts.
Overall, water quality at Phillipsdale Landing was good this week. Weather conditions were dry, with only 0.05 inches on April 30th, recorded at T.F. Green. The Blackstone River flow declined this week, remaining below the 19-year daily median for the majority of the week. Surface salinity averaged 4.1 ppt and ranged from 1.2 ppt to 9.1 ppt. At the bottom, salinity averaged 13.5 ppt and ranged from 2.3 ppt to 27.1 ppt. Temperatures remained stabilized this week, averaging 12.7°C at the surface and ranging 10.0°C – 14.5°C. At the bottom, temperatures averaged 11.3°C and ranged 8.0°C – 14.4°C.
Dissolved oxygen (DO) at Phillipsdale Landing remained above the hypoxia threshold (i.e., DO >2.9 mg/L) throughout the week. Surface DO average 10.5 mg/L and ranged from 9.5 mg/L to 11.7 mg/L.. Bottom DO concentrations averaged 9.3 mg/L and ranged from 8.1 mg/L to 11.3 mg/L. Chlorophyll readings remained comparable from last week, averaging 2.6 ug/L at the surface and 2.9 ug/L at the bottom. Maximum chlorophyll at the surface reached 14.3 ug/L on the afternoon of April 24th. Please note that tidal fluctuations and Blackstone River flows greatly influence water column salinity, temperature, and DO at this location. Also, please note that isolated portions of suspect chlorophyll data from April 28th were excluded from the summary.
Bullock Reach
The Bullock Reach Buoy remains out of the water for the winter. EM will coordinate with RIDEM to redeploy the buoy in late spring.
On April 24th, twenty stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers; five of these stations were also sampled for enterococci bacteria. In the five days prior to sampling, precipitation totaled 0.28 inches as recorded at TF Green. Overall, bacteria counts were lower in both the Seekonk and Providence Rivers this week than during the previous sampling event on March 27th, likely because of the drier weather leading up to sampling.
Fecal coliform counts were higher in the Seekonk River sites than in the Providence River sites (geometric means of 59 MPN/100 mL and 7 MPN/100 mL, respectively). The maximum count (430 MPN/100 mL) was measured at Point St Bridge.
Enterococci results had an overall geometric mean of 14 MPN/100 mL. Enterococci counts ranged from <10 MPN/100 mL at South FP East, Gaspee Point, and Conimicut Point to 41 MPN/100 mL at Phillipsdale Landing.
The next scheduled sampling date is May 8.
The table below lists the Rhode Island bacteria standards for primary contact and shellfishing established by the Rhode Island Department of Environmental Management (RIDEM). RIDEM defines primary contact as any recreational activities in which there is prolonged and intimate contact with water, involving considerable risk of ingesting water (e.g., swimming, diving, water skiing and surfing). Please note that the RIDEM bacteria standards are provided here for informational purposes only and are not intended to indicate official state compliance with primary contact or shellfishing standards.
Summary of Rhode Island Bacteria Standards for Saltwater Primary Contact and Shellfishing
Geometric mean ≤35 colonies/100 mL All samples ≤104 colonies/100 mL2
Shellfishing
Geometric mean ≤14 MPN/100 mL <10% of samples >49 MPN/100 mL3
NO ENTEROCOCCI CRITERIA
1Fecal coliform primary contact criteria applied only when adequate enterococci data are not available; 2Single sample maximum criterion for determining beach swimming advisories at designated beaches as evaluated by the Rhode Island Department of Health; 3For a three-tube decimal dilution
Phytoplankton samples were collected on March 20, 2024 at Bullock Reach and analyzed in the laboratory shortly after collection. It was partly sunny, breeze and brisk on Narragansett Bay. The qualitative tow net sample had a long filtration time, and the filtrate was a dark brown color. Some sediment and jellyfish were found in the sample.
The analysis of the quantitative whole water sample revealed a total of 3,536,000 cells per Liter. The micro flagellates were found at 20,000 cells/L. The most predominant phytoplankton genus was Thalassiosira spp. at 1,888,000 cells/L. Other representative genera include Skeletonema spp. and Leptocylindrus spp. Thalassiosira spp. (today’s featured micrograph, 200x phase contrast) is a type of phytoplankton belonging to the centric diatom group. This photosynthetic species grows primarily in marine waters. Some species within the genus are found in estuaries and aquatic systems that have been impacted by human activities. They can be identified by their coin-like shape.
Due to winter temperatures and weather conditions, boating activities were temporarily halted during the months of December 2023, January 2024, and February 2024. The safety of the crew as well as the boat are of the utmost concern at NBC. Whether it’s slipping on an icy dock or slipping on the boat decking, we don’t want injuries that can be avoided. Although staff wear appropriate gear during colder months, there is great risk to the life and health of crew if they were to slip and fall into the freezing waters during winter months. Staff have been evaluating conditions on a week-to-week basis and are pleased to announce that Nutrient Sampling was able to be conducted on March 6th. Staff are excited to resume boating activities and we are hopeful that favorable conditions continue throughout March. Below is a table showing the bay sites sampled.
Water clarity was measured at eight locations in the Providence River and Seekonk River estuaries on December 13th, 2023. Rainfall totaling 2.29 inches was recorded at TF Green in the five days prior to the survey. Secchi depth averaged 1.3 meters, compared to 4.5 meters on the previous survey (November 30th). The lowest clarity this week (0.7 meters) was measured at Phillipsdale Landing, while the greatest clarity (1.9 meters) was measured at Conimicut Point. There was a general north-to-south gradient of increasing water clarity among the sites this week.
On the morning of December 4th, the Phillipsdale Landing sondes were successfully removed for the 2023 season! For the one day of data available this week, water quality remained good, with similar conditions to last week.
The sondes at Bullock Reach were retrieved on November 14th for the 2023 season.
Overall, water quality was good at Phillipsdale Landing this week. There were 0.74 inches of precipitation recorded at T.F. Green this week, and Blackstone flows continued to be higher than normal for this time of year. Surface salinity averaged 8.0 ppt and ranged from 3.2 ppt to 20.4 ppt. Bottom salinity averaged 19.8 ppt and ranged from 6.2 ppt to 27.2 ppt. Temperatures continued to decline, averaging 6.4°C at the surface and ranging from 3.6°C to 8.8°C. At the bottom, temperatures averaged 8.5°C and ranged from 5.5°C to 10.1°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 was similar to last week, averaging 10.9 mg/L and ranging from 8.8 to 12.4 mg/L. Bottom DO averaged 8.7 mg/L and ranged from 7.3 mg/L to 11.0 mg/L. Chlorophyll readings remained mostly low with a few slightly elevated readings at the bottom. Chlorophyll averaged 0.6 ug/L at the surface and 1.9 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 have been retrieved for the 2023 season.
Overall, water quality was good at Phillipsdale Landing this week. There were 1.82 inches of precipitation recorded at T.F. Green this week, 1.71 of which occurred on 11/22. Blackstone flows were higher than historical averages all week, but particularly following the 11/22 rain event. Surface salinity averaged 8.8 ppt and ranged from 2.9 ppt to 20.7 ppt. Bottom salinity averaged 21.4 ppt and ranged from 6.5 ppt to 27.7 ppt. Temperatures continued to decline, averaging 8.1°C at the surface and ranging from 5.1°C to 10.5°C. At the bottom, temperatures averaged 10.4°C and ranged from 7.2°C to 12.4°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 was slightly higher than the previous week, averaging 10.2 mg/L and ranging from 8.3 to 11.8 mg/L. Bottom DO averaged 7.8 mg/L and ranged from 6.4 mg/L to 11.1 mg/L. Chlorophyll readings remained low, averaging 0.6 ug/L at the surface and 2.6 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 have been retrieved for the 2023 season.
On November 21, 2023, 15 stations were sampled for fecal coliform bacteria in the Providence and Seekonk Rivers; 3 of these stations were also sampled for enterococci bacteria. There was a smaller set of locations sampled than normal due to cold weather conditions and time constraints. In the five days prior to sampling, precipitation totaled 0.15 inches as recorded at TF Green.
Overall, bacteria levels were lower in both the Seekonk and Providence Rivers this week than during the previous sampling event on October 25th. Fecal coliform levels similar in the Seekonk River and Providence River sites (geometric means of 22 MPN/100 mL and 23 MPN/100 mL, respectively). The maximum concentration (230 MPN/100 mL) was measured at Point St Bridge.
Enterococci results had an overall geometric mean of 19 MPN/100 mL and ranged from <10 MPN/100 mL at Phillipsdale Landing and South FP East to 134 MPN/100 mL at Point St. Bridge.
The table below lists the Rhode Island bacteria standards for primary contact and shellfishing established by the Rhode Island Department of Environmental Management (RIDEM). RIDEM defines primary contact as any recreational activities in which there is prolonged and intimate contact with water, involving considerable risk of ingesting water (e.g., swimming, diving, water skiing and surfing). Please note that the RIDEM bacteria standards are provided here for informational purposes only and are not intended to indicate official state compliance with primary contact or shellfishing standards.
Summary of Rhode Island Bacteria Standards for Saltwater Primary Contact and Shellfishing
Geometric mean ≤35 colonies/100 mL All samples ≤104 colonies/100 mL2
Shellfishing
Geometric mean ≤14 MPN/100 mL <10% of samples >49 MPN/100 mL3
NO ENTEROCOCCI CRITERIA
1Fecal coliform primary contact criteria applied only when adequate enterococci data are not available; 2Single sample maximum criterion for determining beach swimming advisories at designated beaches as evaluated by the Rhode Island Department of Health; 3For a three-tube decimal dilution
