There was a smaller low-oxygen “dead zone” and fewer fish kills and sea nettles in the Chesapeake Bay this summer, according to an annual review of summer conditions by scientists with Chesapeake Eco-Check.
The Bay’s summer health is influenced by the amount of water that flows from streams and rivers in winter and spring. This fresh water carries nutrient pollution, which fuels the growth of algae blooms that eventually break down in a process that robs the water of oxygen.
River flow was above average in winter and early spring but below average in late spring and summer. This shifted the intensity of low-oxygen conditions to earlier in the summer. A large, dense algae bloom in the upper to middle Bay in March combined with high temperatures early in summer led to the worst low-oxygen conditions of the summer appearing in late June. After that, below-average flows combined with favorable winds allowed conditions to improve.
Some algae blooms can be toxic to fish, causing large numbers of fish to die in events called “fish kills.” There was only one recorded fish kill linked to toxins from a harmful algae bloom. Three fish kills were the result of low oxygen caused by algae blooms, and seven fish kills were due to low oxygen alone.
The summer review was developed through Chesapeake Eco-Check by scientists with the Chesapeake Bay Program, University of Maryland Center for Environmental Science, Johns Hopkins University, Old Dominion University, University of Michigan and Maryland Department of the Environment.
For more information about the summer review, visit the Chesapeake Eco-Check website.