Study Shows Smaller Late Summer Dead Zone in the Chesapeake
Sixty years of monitoring data analyzed by scientists sponsored by the National Centers for Coastal Ocean Science has revealed a smaller dead zone in late summer in the Chesapeake Bay. The early summer dead zone is larger and seems to have a number of causes, but excessive nutrients are the main culprit for the later dead zone. Nutrients feed large blooms of algae that eventually die and fall to the bottom; their decay takes large amounts of oxygen from the water. Ultimately, this means that management approaches to reduce nutrients flowing into the Chesapeake are working, but that other variables need to be accounted for to shrink the size of the early summer dead zone.
State and federal agencies have been frustrated because despite all of their efforts over the years, the Chesapeake Bay dead zone doesn’t seem to be getting any smaller. This study shows that nutrients alone aren’t the only factor contributing to the size of the hypoxic area, but when those variables are mostly stripped out in the late summer, the algae that are behind the dead zone are reacting to their nutrient “diet.”
This research is highlighted at the 21st Biennial Conference of the Coastal and Estuarine Research Federation, November 6-10, 2011.
- Read the abstract: Murphy, Rebecca. R., W. Michael Kemp, and William P. Ball. 2011. Long-term Trends in Chesapeake Bay Seasonal Hypoxia, Stratification, and Nutrient Loading. Estuaries and Coasts 34 (6): 1293-1309 (August 2011). DOI: 10.1007/s12237-011-9413-7.
- See Coastal and Estuarine Science News for a summary of the article emphasizing management applications.
- Learn more about the research project “Modeling Hypoxia and Ecological Responses to Climate and Nutrients”and the Coastal Hypoxia Research Program.