Reply #19: Oysters as pollution cleaners [View All]

Healthy oysters consume algae and other water-borne nutrients, with each filtering up to five litres of water per hour. Scientists believe that the Chesapeake Bay's once-flourishing oyster populations historically filtered the estuary's entire water volume of excess nutrients in approximately three to four days.

Oysters are known for their role of filtering and removing nitrogen from water.<3> In fact, nitrogen is the main food of phytoplanktons who gather in masses at the surface disallowing sunlight from reaching deeper waters. Oysters feed on plankton and, thus, expel solid pellets of waste which get decomposed into the atmosphere as nitrogen.<4> In Maryland, the Chesapeake Bay Program plans—with the help of oysters—to cut the amount of nitrogen entering the Chesapeake Bay by 19 million pounds a year by 2010.
http://en.wikipedia.org/wiki/Oyster#Marine_pollution