Oysters eat algae. They do this by filtering the water that washes over them. Fertilizer and manure runoff in the rivers upstream promotes excess algae growth. Anything solid that is filtered by the oyster and is not algae is turned to sand and drops to the bottom. In this way, the oyster removes turbidity and excess algae that clouds the water, blocking the sun's rays from getting to submerged vegetation.  Oyster reefs create habitat for hatchling fish and become natural fish havens. They also prevent erosion from wave action. In this way, waterfront property is protected from storms. More oyster reefs means more oysters releasing oyster embryos into the water which means more oysters setting on public and private oyster grounds for watermen to harvest.