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Oysters Could Help Clean Hawaii's Polluted Waterways

U.S. Fish and Wildlife Service

Some of Hawaii's most polluted waterways may soon get help from an unlikely source: oysters. After a successful test project in Pearl Harbor, the Hawaiian Islands branch of the Waterkeeper Alliance is seeking to expand the use of oyster colonies to clean polluted waters. 

Credit U.S. Army Corps of Engineers
Oyster shells are deposited into the Chesapeake Bay. The shells form the foundation for a new reef of live oysters to colonize.

The technique is already being employed in other extremely polluted bodies of water around the nation. In the Chesapeake Bay, the U.S. Army Corps of Engineers has been rebuilding traditional oyster reefs using shells from mollusks consumed in restaurants. In New York Harbor, the Billion Oyster Project has already installed millions of individual oyster colonies. When complete, that project will totally filter the entire harbor every three days.

Here in Hawaii, native oysters were once abundant in Pearl Harbor, hence the harbor's name. The Department of Land and Natural Resources and the navy recently planted a test crop of oysters in Pearl Harbor's West Loch. That project's success has prompted Waiwai Ola Waterkeepers Hawaiian Islands to explore expanding the effort to other waterways.

Credit Youtube
A demonstration tank shows the difference between untreated and oyster filtered water. In some parts of the Chesapeake, water visibility has increased by 20 feet.

The group will be conducting a similar test in Maui's Ma'alaea Harbor in conjunction with the Maui Nui Marine Resource Council. They are also exploring oyster-based options for cleaning up the much maligned Ala Wai Canal in Waikiki. 

The technique is not harmful to the oysters, whose feeding process naturally filters the surrounding water. The shellfish can absorb almost anything including excess nitrogen from fertilizer, heavy metals, PCB's, and sediment from strom runoff. Useful materials are abosrbed and help grow the oyster's shell. Everything else is contained in a mucus secretion and eventually sinks to the ocean floor. 

No annoucement has yet been made by the navy or the State of Hawaii on expanding the successful test at Pearl Harbor.

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