Fish, crabs and other aquatic life in the Chesapeake Bay are literally getting more breathing room this summer. Recent monitoring shows that the size of the oxygen-starved “dead zone” in late June was the second smallest since 1985, when the Baywide monitoring program began.
The Maryland Department of Natural Resources reported this week that the amount of low-oxygen, or hypoxic, water in the mainstem of the Chesapeake was about 0.42 cubic miles, significantly less than the long-term average of 1.11 cubic miles during late June monitoring. It was also slightly better than the 0.5 cubic miles of hypoxic water (areas with less than 2 milligrams of oxygen per liter) that was observed in early June, according to DNR scientists.
The monitoring also found no areas of anoxic water — areas with no oxygen at all.
That was also better than the forecast of scientists who had predicted a near-average area of hypoxic water, largely based on the amount of nutrients and water entering from the Susquehanna River during the spring, as well as other environmental factors. The forecast, made by scientists at the University of Michigan, the University of Maryland Center for Environmental Science, and the National Oceanic and Atmospheric Administration had also predicted an anoxic area that would cover 0.28 cubic miles in early summer and would expand to 0.31 cubic miles by late summer.
Scientists in Maryland and Virginia will monitor conditions through the summer.
Having adequate dissolved oxygen is critical for crabs, fish, oysters and most other aquatic life. Improving oxygen levels in the Bay is a key goal of region’s nutrient reduction efforts. When excess amounts of nitrogen and phosphorus enter the Chesapeake, they fuel the growth of algae blooms. When the algae die, they sink to the bottom and are decomposed by bacteria in a process that draws oxygen out of the water.