Today, the Chesapeake Bay Program announced that the Maryland Department of Natural Resources reported that the 2020 dead zone is the second smallest observed in the Maryland portion of the Chesapeake Bay since monitoring began in 1985. The Bay Program also announced that researchers from the Virginia Institute of Marine Science reported the dead zone there was smaller than 80 percent of dead zones reported in the 35 previous years.
The dead zone is composed of portions of the Bay that have little or no dissolved oxygen. These areas are caused when algae blooms fed by nitrogen and phosphorus pollution decompose, removing oxygen from the water. The low oxygen areas are inhospitable to marine life such as crabs and fish.
This news is encouraging as it suggests that the Bay is responding to pollution reduction efforts by starting to help itself. In a 2018 paper, University of Maryland scientists detected that as the dead zone grows smaller, bio-chemical changes result in less fuel for algae and oxygen-consuming bacteria, and therefore more oxygen in bottom waters. The observation that this year’s dead zone started later and ended earlier than normal is consistent with this change.
The Bay Program attributed the decrease in the dead zone to ongoing state pollution reduction efforts as part of the Chesapeake Bay Clean Water Blueprint as well as a cool spring and summer rains that helped mix oxygen into the water. Chesapeake Bay Foundation (CBF) has been advocating for states to ramp up pollution reduction efforts ahead of the cleanup’s 2025 deadline.
In response to the news about the small dead zone, CBF Director of Science Beth McGee issued the following statement:
“This year’s small dead zone is another positive sign that watershed-wide Chesapeake Bay cleanup efforts are working. As the 2025 deadline looms, we’re encouraging states to figure out new ways to reach pollution reduction goals, including by adding more natural filters to the landscape such as trees, grass pastures, and wetlands. Doing so will increase the resiliency of the Bay and help it handle the influx of nitrogen and phosphorus pollution.
“A smaller dead zone means more areas for oysters, crabs, and fish, to thrive in the Bay. This is good news.”