Gulf River 2016


 

In 2016, CSCR students and staff began surveying shellfish in the Gulf. Click here to view the live, editable Gulf River Shellfish Survey map.

Project Sites:Gulf River from the Border St Bridge to Gannet Road in N. Scituate

 

Leaders: Ann Thomae, Ben Wetherill

 2016 Highlights:

  • 7 weeks of sampling
  • 4 sites
  • 2 samples per site per week
  • 56 total water samples collected

 

Each sample analyzed for…

  • Dissolved oxygen
  • Salinity / Conductivity
  • Temperature
  • Enterococcus bacteria
  • pH
  • Chlorophyll-a

 

Learned and started using a new test method for Nitrates

 

  • Lower detection limit of 0.04 mg/L vs. the previous method of 1 mg/L
  • Gulf River samples are in the range 0.05-0.2 mg/L, so this allows us to confidently assess concentrations

 

 
 
 

Gulf 2016 Preliminary Summary 

In general, the health of the Gulf looks very good. We still need time for the analysis of the data, but we have seen no data that reflects eutrophication conditions or nutrient contamination.

Dissolved oxygen – All DO values fell within the normal ranges for %saturation and mg/l. Only one or two samples where DO levels were abnormally low. Still need to assess what conditions might have caused them.

Chlorophyll-a – Chlorophyll levels seem to fluctuate within healthy ranges, with the highest values in shallow waters at low tides.

Nitrates – Nitrates are extremely low, meaning that nitrogen is probably being completely consumed by phytoplankton and algae. This could hint that nitrogen is a limiting nutrient in the Gulf and that phosphorous is in large supply. A future opportunity for us could be to start measuring phosphorous.

Bacteria – Bacteria counts are consistently very low everywhere except Hunters. We need to do more studies to evaluate the source of the bacteria at Hunters. This might require building CSCR staff and skills to differentiate animal and human bacteria.

The strong tidal flow is critical for the Gulf, and keeps it fairly well flushed and oxygenated. 

It is important for us to keep thinking about the Hunters Pond dam removal scheduled for fall 2017. Dr. Sara Grady and her colleagues at the state level may suggest protocols for us to test in the spring and summer of 2017 in order to develop baseline data for post dam removal comparison.