2020 – A Good Year For Oysters In The Severn!

ANNAPOLIS (October 10, 2020) — Despite the trials and challenges we all have faced on land from the Covid-19 pandemic, this was a good year for oysters in the Severn River, and now, conditions are greatly improving for them going into fall and winter.

Just released water quality monitoring data, collected by the Severn River Association, show that conditions for our bivalve pals ranged from tolerable to thriving this summer.

Thriving means when oxygen levels are more than 5 mg/L of oxygen on the bottom where the oysters live (see green line in the chart below).

SRA’s Water Quality monitoring program is made possible by a grant from Delaplaine Foundation and support from SRA members and donors.

Their continued support allows our team of citizen scientists to visit 44 stations every week to check on the health of the river and 17 creeks.

SRA’s Field Investigator, Emi McGeady, who runs SRA’s river-wide monitoring program, says that at no time during the summer did our oysters have to deal with dead zone conditions. A dead zone occurs when oxygen levels fall to less than 2 mg/L in the river and creeks (see red line in chart below).

There’s more good news revealed in the WQ monitoring data. Oxygen levels have rebounded tremendously since September 17. They are now well above the 5 mg/L level (see the green line in the chart below) preferred by oysters.  “They’ll be thriving all fall and winter,” she says.

This in sharp contrast to conditions in the rest of the Severn River, which suffered through extensive periods of dead zone conditions that caused some isolated fish and crab kills this summer.

Good Salinity Levels, Too

There’s another reason our oysters are in good shape. In early June, McGeady explained that salinity levels improved for oysters and the trend is holding steady for a winter of more normal conditions for a brackish waterway.

Oysters thrive when salinity ranges from 8 to 15 parts per thousand (see chart below).

You can join the team and become one of our WQ Crew. This is a wonderful opportunity for volunteers who have a free morning during the week. Each WQ tour takes about three hours, usually on Wednesday, Thursday and Friday mornings.

All the data collected is shared with the scientific and regulatory communities through our partnership with the Chesapeake Monitoring Cooperative and the Chesapeake Data Explorer.  SRA is a certified Tier 2 monitoring organization with the Cooperative.

For more information, email Info@severnriver.org and put WQ Crew in the message box.

Photo: Lisa Borre.