Snapshot of the Bay

Historical News

Week of December 30, 2018 - January 5, 2019

Phytoplankton Sampling

Phytoplankton samples were collected at Bullock's Reach on January 3, 2019 and analyzed in the laboratory shortly after collection. It was a cold and rainy day on Narragansett Bay. Sondes data revealed the surface water temperature was 4.46^oC, salinity was 14.18 psu, and chlorophyll a was 3.1 ug/L. The plankton tow net sample was filterable with a 20 micron mesh. The filtrate was light golden brown with noticeable particulate matter and 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 193,000 cells per Liter. The most predominant phytoplankton was Skeletonema at 154,000 cells/L. The flagellates were found at 5,000 cells/L and other representative genera include Leptocylindrus spp. and Thalassionema spp.

200x phase contrast micrograph of Odontella spp.

2 odontella spp.jpg

Week of December 23 - 29, 2018

Water Column Profiles

Water column profiles were measured at two sites (Edgewood Yacht Club and Pomham Rocks) in the Providence River on December 27, 2018.

The five days prior to this survey were dry, with only 0.05 inches of rainfall recorded. The water column was well mixed at both sites, though surface salinity (24-25 psu) recorded at Edgewood Yacht Club was slightly lower than bottom salinity (28 psu) at this site. Salinity at Pomham Rocks only ranged 27 psu at the surface to 28 psu at the bottom. Temperatures were similarly uniform, ranging only from 6.5°C at the surface at Edgewood to 7.2°C near the bottom at this same site. Dissolved oxygen (DO) was high throughout the water column, with a minimum result of 8.9 mg/L observed near the bottom at Edgewood. Fluorescence was low at all sites, with the maximum (1.39 mg/m³) observed at 1.5 meters depth at Pomham Rocks.

Week of December 30, 2018 - January 5, 2019

R/V Monitor's Blog

The crew of the R/V Monitor was out on the upper Bay twice this week. First, on Wednesday, January 2nd staff conducted side-by- side tests of the old Seabird instrument with the new Seabird profiler, to ensure repeatability and accuracy of the new monitoring equipment. Sara captained the boat while monitoring professionals Fern and Mike conducted the profiles. It was a cool sunny day with no wind. The water was extremely calm this day. On Thursday, January 3rd, the crew was out once again collecting nutrients and plankton samples, taking Secchi Disk and Par sensor water clarity measurements, conducting water column profiles, using both the new and old Seabird instruments side-by-side, 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. Sara captained the boat while monitoring professionals Amanda, Steve and Mike collected the samples and data. The day began rainy with no wind, but cleared in the afternoon and became breezy and quite cold. The photo below was taken on the 2nd and features NBC's new and old Seabird instruments being lowered together for a side-by-side comparison test.

1-2-19 Seabird Cast.jpg

Week of October 14 - 20, 2018

Benthic Video Blog

The boat crew conducted benthic video surveys along all three permanent transect locations on October 19th. Scale lasers were used in the footage, separated by 29 cm. Visibility through the water column was moderate.

The bottom was characterized by muddy sand along both transects, though Sabin also has an extensive area of boulders and areas covered in clam shell rubble; several small fishes were observed using the shell rubble as habitat structure. One larger fish, a summer flounder (Paralichthys dentatus) was observed along the Bullock Reach transect. Common observations along all transects included hermit crabs, boring sponges in clam shells, small-medium infaunal burrows, large burrow openings (likely from the mantis shrimp, Squilla) and parchment tube worms (Chaetopteridae; particularly abundant along Bullock Reach). Mudsnails were highly abundant along the Edgewood transect (see photo), while seastars were observed along the Sabin transect. Sparse algae (Ulva and Grateloupia, mainly) were observed in all areas, but there were no extensive rafts; similarly, no amphipod tube mats were observed.

Week of December 16 - 22, 2018

Water Column Clarity

Water clarity was measured at five locations in the Providence and Seekonk Rivers on December 19, 2018. In the five days prior to sampling, 0.91 inches of rainfall occurred. Average water clarity increased from the previous sampling, from 1.6 m to 2.8 m.

Water clarity increased at all five sites sampled: India Point, Pomham Rocks, Edgewood Yacht Club, Pawtuxet Cove, and Conimicut Point. The largest increase in clarity, 2.2 m, occurred at India Point. Secchi depth ranged from 1.83 m at Pawtuxet Cove to 3.63 m at India Point. There was evidence of a slight north to south water clarity gradient.