Historical News

Week of August 12 - 18, 2021

Benthic Video Blog

​The boat crew conducted benthic video surveys along the Bullock Reach, Edgewood, and Sabin transects on August 17, 2021. Scale lasers were used in the footage, separated by 29 cm (no lasers visible at Sabin). Visibility through the water column was fair to good this week across the transects. The bottom of all sites was characterized by sands and muds. Sabin and Bullock Reach both hosted dense patches of shell hash and rubble, as well as areas of cobbles and boulders at Sabin. All sites featured sparse patches of branched algae and Ulva, with Sabin additionally having large areas of dense filamentous algae. Dense diatom felt was also present at Sabin and Bullock Reach. Sabin and Bullock Reach experienced higher general biotic activity as noted by frequent tracks and trails, as well as observed faunal diversity. Rare benthic video sights included many small schools of juvenile black sea bass (all sites), mantis shrimp Squilla (Sabin and Edgewood), horseshoe crab (Bullock Reach), egg masses produced by the lugworm Arenicola (Edgewood), and a sea star (Sabin). Infaunal activity was highest at Sabin and Edgewood this week. Frequent large burrows (likely from Squilla), small burrows, parchment tubes, and other tube-building fauna were present at all sites. Common observations were spider crabs (Bullock Reach, image below), boring sponges (all sites), blue crab (Sabin), hermit crabs (all sites), ctenophore swarms (all sites), slipper snail Crepidula (all sites), Nassariid mudsnails (Bullock Reach and Edgewood), and large colonies of mermaid’s glove sponges and red bearded sponges (Sabin). Dense amphipod tube mats were observed at both Sabin and Edgewood. ​

Please note: this blog publication has been post-dated to retain chronological order as a backlog of video footage is reviewed.​

BR SPIDER.PNG ​

Week of August 22 – 28, 2021

Nutrients Sampling

Nutrient samples were collected from thirteen local and border river stations and eight bay stations on August 25, 2021. Nearly 1 inch of rainfall was recorded at T.F. Green in the three days prior to sampling.

Among the river stations sampled, total nitrogen (TN) ranged from 462 ppb (average of 2 duplicates) at Moshassuck River at Higginson Ave. to 1,530 ppb at the Warren Reservoir/Kickemuit River. Concentrations of total dissolved nitrogen (TDN) were also lowest at the Moshassuck River at Higginson Ave. site (average of two duplicates = 468 ppb), while highest TDN concentration was measured at the Ten Mile River at Central Ave. site (1,260 ppb). Additionally, dissolved inorganic nitrogen (DIN) ranged from 163 ppb at the Runnins River at River Road sampling location to 901.3 ppb at the Ten Mile River at Central Ave. site.

Among the Bay stations sampled, the highest nitrogen results occurred at Pawtuxet Cove, which had TN, TDN, and DIN results of 944 ppb, 1,140 ppb, and 613.4 ppb, respectively. The lowest TN (540 ppb), TDN (662 ppb), and DIN (115.2 ppb) occurred at the Bullock Reach Buoy site (average of duplicates reported). Chlorophyll a concentration at the Bay sites decreased from the previous week, averaging 8.68 ug/L. The maximum chlorophyll result, 16.77 ug/L, occurred in one of the duplicate samples at Bullock Reach Buoy (average of duplicates = 14.38 ug/L).

Results from nutrient sampling on September 8 and September 22 are pending analysis. The next scheduled sample date is October 6.

Week of August 22 – 28, 2021

Fixed Site Network

Phillipsdale Landing
Water quality at Phillipsdale Landing was fair-to-poor this week. Conditions this week were mostly wet, with 1.78 inches of rainfall recorded at TF Green. Blackstone River flows remained elevated over historical median levels, based on heavy rainfall this week. Surface salinity averaged 5.4 ppt, with a maximum value of 13.1 ppt. Bottom salinity averaged 17.2 ppt, with a maximum value of 27.5 ppt. Water temperatures averaged 25.4°C on the surface and 24.3°C on the bottom. Temperatures ranged from 23.6°C to 29.1°C at the surface and from 23.3°C to 26.1°C at the bottom.

This week, surface dissolved oxygen (DO) averaged 6.3 mg/L, with a minimum of 3.9 mg/L. Bottom DO generally decreased over the course of the week and ranged from 1.7 mg/L to 6.8 mg/L; bottom hypoxia (DO ≤ 2.9 mg/L) was common. Chlorophyll concentrations were lower than the previous week, averaging 5.6 ug/L on the surface and 4.8 ug/L on the bottom, with a surface maximum of 17.7 ug/L. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach
Water quality at Bullock Reach was fair-to-poor this week. Sondes were changed out for routine maintenance on August 24. Salinity generally increased slightly over the course of the week, averaging 22.2 ppt at the surface, 27.3 ppt at mid-depth, and 29.9 ppt in bottom waters. Salinity ranged from 18.3 ppt to 26.1 ppt at the surface, 21.6 ppt to 29.6 ppt at the mid-depth, and 27.9 ppt to 31.2 ppt at the bottom. Surface temperature averaged 25.4°C and ranged 24.0°C – 27.8°C, mid temperatures averaged 24.3°C and ranged 23.4°C – 26.0°C, and bottom temperatures averaged 23.2°C and ranged 22.3°C – 24.2°C.

This week, DO averaged 7.5 mg/L at the surface, 4.8 mg/L at mid-depth, and 3.9 mg/L at the bottom. Hypoxic conditions (DO ≤ 2.9 mg/L) were observed at the mid and bottom depths. The minimum DO value, 2.6 mg/L, occurred in bottom waters on August 28, during a period of hypoxic conditions that lasted approximately two hours. Chlorophyll concentrations averaged 15.7 ug/L at the surface, 9.8 ug/L at mid-depth, and 1.7 ug/L at the bottom. The maximum chlorophyll value in surface waters was 119.4 ug/L.​

Week of August 8 – 14, 2021

Nutrients Sampling

Nutrient samples were collected from seven local and border river stations and seven bay stations (surface and bottom) on August 11, 2021. In the five days prior to sampling, only trace amounts of rainfall were 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 occurred at the Pawtuxet River at Broad St. site. At this sampling location, TN, TDN, and DIN concentrations were 1,220 ppb, 1,420 ppb, and 1,080.3 ppb, respectively. The lowest nitrogen concentrations occurred at Moshassuck River at Higginson Ave., with concentrations of 418 ppb (TN), 500 ppb (TDN), and 252.1 ppb (DIN).

Among the Bay surface station results, TN ranged from 375 ppb at Conimicut Point to 715 ppb at Phillipsdale Landing. Lowest TDN (139 ppb) occurred at Bullock Reach Buoy, while the greatest TDN value occurred at Phillipsdale Landing (706 ppb). Additionally, DIN ranged from 13.0 ppb at Edgewood Yacht Club to 431.6 ppb at Phillipsdale Landing. Chlorophyll a concentration at the Bay sites decreased since the previous sampling at the end of July, averaging 16.23 ug/L. The maximum result of 25.06 ug/L occurred at Phillipsdale Landing. 

Results from nutrient sampling on August 25 and September 8 are pending analysis. The next scheduled sample date is September 22.

Week of August 15 – 21, 2021

Fixed Site Network

Phillipsdale Landing
Water quality at Phillipsdale Landing was fair-to-poor this week. Sondes were changed out for routine maintenance on August 17. Rainfall this week totaled 0.44 inches at TF Green, with all of it occurring on August 19.  Blackstone River flows were mostly low through most of the week but were elevated following the rain event on August 19. Salinity at the surface averaged 12.6 ppt and ranged from 1.5 ppt to 23.0 ppt, while bottom salinity averaged 21.2 ppt and ranged from 3.9 ppt to 27.8 ppt. Surface water temperatures this week were slightly warmer than the previous week, averaging 24.8°C and ranging from 22.9°C to 26.7°C. Bottom water temperatures averaged 23.9°C and ranged from 22.1°C to 26.0°C.

This week, surface dissolved oxygen (DO) averaged 6.1 mg/L, with a minimum of 2.1 mg/L, while bottom DO averaged 2.8 mg/L, with a minimum of 0.7 mg/L. Although, prolonged periods of hypoxic conditions (DO ≤ 2.9 mg/L) were observed in bottom waters throughout the course of the week, bottom DO generally increased as the week progressed. A maximum duration of hypoxia of approximately 2 days occurred from August 15 to August 17. Chlorophyll concentration averaged 19.0 ug/L on the surface and 11.6 ug/L on the bottom, with a surface maximum of 83.3 ug/L. Please note that tidal fluctuations and Blackstone River flow greatly influence water column salinity, temperature, and DO at this location.

Bullock Reach
Water quality at Bullock Reach was fair-to-poor this week. Overall, salinity remained similar over the course of the week, averaging 25.7 ppt at the surface, 28.2 ppt at mid-depth, and 30.2 ppt in bottom waters. Lowest salinity (21.8 ppt) occurred in surface waters, while greatest salinity (31.7 ppt) occurred in bottom waters. Temperatures averaged 24.5°C, 23.8°C, and 22.5°C at the surface, mid, and bottom, respectively. Surface temperatures ranged from 23.3°C to 26.3°C, mid temperatures ranged from 21.8°C to 25.4°C, and bottom temperatures ranged from 20.9°C to 24.4°C.

This week, DO averaged 7.1 mg/L at the surface, 5.1 mg/L at mid-depth, and 3.4 mg/L at the bottom. Hypoxic conditions (DO ≤ 2.9 mg/L) were observed at the mid and bottom depths. The minimum DO value, 1.8 mg/L, occurred in bottom waters during the morning of August 17, which was during a period of prolonged hypoxia that lasted approximately 25 hours. Chlorophyll concentrations averaged 10.4 ug/L at the surface, 5.6 ug/L at mid-depth, and 4.4 ug/L at the bottom. The maximum chlorophyl value in surface waters was 36.6 ug/L. ​

Newer Posts
Older Posts