Historical News
R/V Monitor's Blog
On Tuesday, February 16th, the crew of the R/V Monitor was out on the upper Bay collecting bacteria samples, and conducting real-time surface mapping of water quality parameters, including dissolved oxygen, chlorophyll, water temperature, salinity, and pH, all in an effort to document water quality improvements associated with NBC construction projects. Jeff captained the boat while monitoring professionals Sara and Daryll collected the samples and data. The weather was raw and rainy, with wind and a chop on the water. Visibility was about 1/2 mile. The featured photo taken from the boat cabin reveals the conditions experienced on the Bay this day.
Surface Mapping
Data
were collected on February 16, 2021 while the R/V Monitor was underway
collecting bacteria samples in the Seekonk and Providence River estuaries. The
chlorophyll concentrations were good to poor in the areas surveyed, in a north
to south gradient. From north to south, average chlorophyll concentrations were
as follows: Seekonk River (5.74 µg/L), Upper Providence River (10.81 µg/L),
Edgewood Shoals area (15.01 µg/L), Pawtuxet River area (18.17 µg/L), and Lower
Providence River area (20.59 µg/L). Overall, chlorophyll ranged between 0.30
µg/L and 38.30 µg/L with an overall average of 10.32 µg/L. The chlorophyll data
from this date are presented in the map below:
Bacteria Sampling
Phytoplankton Sampling
Phytoplankton samples were collected on January 13, 2021 at Bullock Reach and analyzed in the laboratory shortly after collection. It was a sunny beautiful day on Narragansett Bay. Sondes data revealed the surface water temperature was 4.57°C, salinity was 21.90 psu, and chlorophyll a was 0.4 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was a light gold color and had a medium filter time. The tow net sample was analyzed qualitatively for microorganisms using 100x phase contrast microscopy. The whole water sample was analyzed quantitatively under 200x phase contrast microscopy. A Hensen Stempel pipette was used to accurately deliver 1ml of sample to a Sedge-wick Rafter chamber. This analysis revealed a total of 143,000 cells per Liter. The flagellates were found at 8,000 cells/L. The most predominant phytoplankton was Skeletonema spp. at 93,000 cells/L. Representative genera include Chaetoceros spp., Thalassiosira spp. and estuarine diatoms.
200x phase contrast image of Dinobyron spp.
Water Column Clarity
Water clarity was measured at six locations in the Providence River on January 13, 2021. No rainfall was recorded on the day of the survey and in the three days prior, leading to an increase in water clarity compared to the previous survey day. Overall, sites survey averaged 3.13 meters Secchi depth, compared to 1.23 meters on December 2, 2020. The lowest clarity (2.03 meters) was measured at India Point Park, while the greatest clarity (5.83 meters) was measured at Conimicut Point Park. Overall, a slight gradient of increasing clarity from north to south was observed among all sites.
