MOBILE, Ala. (AP) — Scientists with Auburn University and the Dauphin Island Sea Lab say there are limits to how much pollution oysters can clean up.
Adult oysters are known to filter about 50 gallons of water daily. The Mobile Press-Register reports (http://bit.ly/NuL1aO) after 10 years of study, scientists figured out a way to measure how much nitrogen an oyster can remove each day as it pumps water through its body. Nitrogen is one of the key nutrients responsible for the creation of the dead zone that builds in Mobile Bay each year.
Nitrogen fuels the growth of phytoplankton and of algae, which dies, falls to the bottom and decays. The decay process consumes oxygen, leaving the water with too little oxygen to support fish and other marine life.
Dauphin Island Sea Lab scientist Ruth Carmichael says the study showed the limits of what oyster reefs can do as part of a system to clean up pollution. She says the challenge in Mobile Bay is understanding how much nitrogen is coming into the system and what the sources are.
“In the water bodies that are the most polluted, there’s just not space available,” Carmichael said. “In the most polluted urban estuaries, you just don’t have enough room for the oysters. You would have to blanket the bottom of the entire estuary in oysters.”
Work is underway to determine the sources of the nitrogen, which will help scientists calculate how much of the problem the bay’s oyster reefs can be expected to help fix.
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Information from: Press-Register, http://www.al.com/press-register/
