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Protecting Bay Seafood From The Dead Zone
Protecting Bay Seafood From The Dead Zone
The combination of pollution reduction practices and below-average rainfall resulted in a historically small “dead zone” in the Chesapeake Bay in 2023, according to the Virginia Institute of Marine Science (VIMS) annual report.
It indicates that that hypoxic, low-oxygen conditions last year were at their lowest since monitoring began in 1985. These results concur with a separate report issued by the Chesapeake Bay Program in conjunction with the Maryland Department of Natural Resources (MD DNR).
On April 18, Long Branch Historic Home in Millwood will feature a talk by William & Mary dean and VIMS director Dr. Derek Aday starting at 6 p.m. He’s expected to share the many ways his department is involved in protecting local seafood as well as Virginia’s preparedness for flooding and storm events, and healthier waterways in Virginia and around the globe.
The dead zone report is quite significant, and quite unexpected.
“The low levels of hypoxia in 2023, despite the high temperatures, are truly surprising,” said Dr. Marjy Friedrichs, a VIMS professor. “This may finally be clear evidence that our nutrient reduction strategies are improving water quality and fish and shellfish habitats.”
Dr. Aaron Bever of Anchor QEA, LLC and coauthor of the Chesapeake Bay Dead Zone Report Card with Friedrichs added, “It’s great that the Bay has now had relatively low amounts of hypoxia for multiple years. This shows that nutrient reductions are having a positive impact on the health of the Bay and Bay habitat.”
Dead zones are areas of low oxygen (less than two milligrams per liter of oxygen) that form in deep Bay waters when nutrients enter the water through polluted runoff and feed naturally-occurring algae.
This drives the growth of algal blooms, which eventually die and decompose, removing oxygen from the surrounding waters faster than it can be replenished. This creates low-oxygen—or hypoxic— conditions at the bottom of the Bay that limit habitat for crabs, oysters, fish, and other wildlife.
Researchers track Bay oxygen conditions using a variety of methods. Oxygen and nutrient levels are routinely measured as part of the Chesapeake Bay Water Quality Monitoring Program, a Bay-wide cooperative effort involving watershed jurisdictions, several federal agencies, 10 academic institutions, and more than 30 scientists.
The 2023 dead zone could have been even smaller if not for the season’s above average temperatures and average wind speeds. Warmer air leads to warmer Bay waters, which in turn hold less oxygen and support higher rates of oxygen consumption by microorganisms.
Faster wind speeds help mix oxygen into the deeper waters of the Bay, which can prevent hypoxic conditions. In addition to the weather conditions, the size and duration of the Bay’s dead zone is affected by the amount of nutrients entering the Chesapeake from its surrounding watershed.
To register for the Long Branch event, call Crystal Booker at VIMS at 804-684-7099
