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Largest Oxygen-Deprived Dead Zones in Chesapeake Bay Since 2014

Ecologist and colleagues from several institutions had predicted a larger-than-average Chesapeake Bay "dead zone" in 2017.




What are "Dead Zones"?
Dead Zones are areas of water with a low amount of oxygen in the bay. These "Dead Zones" are caused by Nitrogen and Phosphorus pollution created by people. without oxygen in the water aquatic animals like fish, crabs and oysters suffocate. 

An excess amount of nutrients also increase the growth of dense algae blooms that block sunlight that underwater plants need to grow to provide food for waterfowl and shelter for crabs and young fish. Dead Zones are as barren and lifeless as the face of the moon.



How serious is this problem?
A few years ago in Mattox Creek, Virginia 296,000 fish were killed by a dead zone. These fish included menhaden, white perch, croaker, gizzard shad, catfish, American eel, large-mouth bass and blue crabs. This happened because the algae bloom grew and extended over 30 miles between Mathias Point and Nomini Bay on the Maryland-Virginia line. 

If there are excessive amounts of nitrogen and phosphorus in the water, algae can bloom to harmful levels eventually taking away dissolved oxygen from the water when they die and decay. This oxygen is crucial to the health of the Chesapeake Bay.



Where is all this pollution coming from?
These nutrients come from Wastewater treatment plants, Runoff, and Air pollution.

Researchers say the total amount of oxygen-deprived dead zones in the Chesapeake Bay this summer was the biggest since 2014.
Measurements of the Chesapeake Bay's dead zone go back to 1950, and the 30-year mean maximum dead zone volume is 1.74 cubic miles.

The anoxic portion of the zone, which contains no oxygen at all, is predicted to be 0.35 cubic miles in early summer, growing to 0.49 cubic miles by late summer—both of which are at or slightly above average. Above-average nutrient loading from the Susquehanna River this spring accounts for the overall slightly larger-than-average predicted the size of the anoxic portion.


The bay's hypnotic (low-oxygen) and anoxic zones are caused by excess nutrient pollution, primarily from agriculture and wastewater. The excess nutrients stimulate an overgrowth of algae, which then sinks and decomposes in the water. The resulting low oxygen levels are insufficient to support most marine life and habitats in near-bottom waters, threatening the bay's crabs, oysters, and other fisheries.


"The forecast calls for an above-average dead zone in the Chesapeake Bay this year, illustrating that more work needs to be done. The dead zone remains considerably larger than the size implied by the targets set under the Chesapeake Bay Total Maximum Daily Load agreement," said U-M aquatic ecologist Don Scavia, U-M professor of natural resources and environmental engineering.


Scavia is a member of the NOAA-funded teams that produce annual forecasts for the Gulf of Mexico, Chesapeake Bay and Lake Erie. This year's Gulf forecast will be issued this month, and the Lake Erie harmful algal bloom forecast will be released in early July.


Spring rainfall plays an important role in determining the size of the Chesapeake Bay hypoxic zone. In spring 2017, the Susquehanna River delivered 81.4 million pounds of nitrogen into the bay, which is slightly greater than the long-term average. Rainfall amounts were greatest in New York and Pennsylvania, leading to higher than average streamflow into the bay from the Susquehanna.


"Despite this year's forecast, we've made great strides in reducing nutrient pollution from various sources entering the Chesapeake Bay, and we are starting to see positive long-term signs," said Rob Magnien, director of NOAA's Center for Sponsored Coastal Ocean Research. "However, more work needs to be done to address indirect nutrient pollution from farms and other developed lands, to make the bay cleaner for its communities and economic interests."


The bay outlook is based on models developed by NOAA-sponsored researchers at the University of Maryland Center for Environmental Science and the University of Michigan. They rely on nutrient-loading estimates from the U.S. Geological Survey.


Throughout the year, researchers measure oxygen and nutrient levels as part of the Chesapeake Bay Monitoring Program, run by the Maryland Department of Natural Resources and the Virginia Department of Environmental Quality. This year's findings will be released in the fall.


"The USGS supports this forecast by calculating nutrient loads based on its stream-flow gauges and water-quality sampling sites," said Don Cline, associate director for the USGS Water Mission Area. "The USGS and Maryland have maintained a monitoring partnership for over 30 years in order to track conditions in the Chesapeake Bay and its tributaries. These data are all publicly accessible at waterdata.usgs.gov."



Current Efforts
The EPA established a Chesapeake Bay total maximum daily load. It sets the maximum amount of pollution the bay can receive and still keep water quality standards and identifies specific pollution reduction requirements. 

The TMDL requires all reduction measures to be in place by 2025, at least 60% of the actions completed by 2017. Maryland has committed to the schedule.EPA will review each jurisdiction's progress. If their plans are inadequate EPA may take action to ensure pollution reduction. 

But this effort lacks a strategy for accounting for new pollution and paying for restoration acts.


Original text found on PHYS.ORG... https://phys.org/news/2017-10-chesapeake-bay-dead-zones-biggest.html



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