Healthy oyster reefs provide a wide range of ecosystem services, and one of the most important is the ability to improve water quality. Studies have shown that adult oysters have the capability of filtering between 30 and 60 gallons of water per day. During the filtration process, oysters remove phytoplankton and zooplankton (vital food sources) as well as suspended sediments and excess nutrients such as nitrogen and phosphorus. While nutrients are a necessary food source for plankton, excessive levels can result in harmful algae blooms, a reduction in water clarity, the depletion of dissolved oxygen which leads to fish kills, and an overall degradation of water quality. A recent study in the Choptank River in Maryland (Denitrification and Nutrient Assimilation on a Restored Oyster Reef) further supports the significance of the role that healthy oyster reefs play in water quality improvement. The study determined that oyster reefs remove a considerable amount of nitrogen through the denitrification process. In fact, one acre of a restored reef was shown to remove up to 543 pounds of nitrogen per year.
Time-lapse video demonstrating oysters removing pollutants from water: