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Water-cleansing at Malibu Bay: 200 oysters are leading the charge

The day was cold and blustery but the prospects for Dorchester’s Malibu Bay become noticeably brighter with the reintroduction of water cleansing oysters on Sat., Nov. 28. Each oyster can filter 30 gallons of water per day, removing silt, plankton, bacteria, and heavy metals from the water column. Approximately 200 oysters were placed in milk crate cages off of the docks at Dorchester Yacht Club under the auspices of the non-profit Massachusetts Oyster Project in conjunction with Dr. Anamarija Frankic and her students at UMass-Boston.

The red flag indicating unsafe water quality is an unwelcome sign at Malibu Beach, and it is raised with greater frequency than anyone would like. A large part of the problem is Combined Sewer Overflows (CSOs) that release minimally treated waste water into the harbor during periods of heavy rains. Andrew Jay, founder of the Oyster Project, points out that “while there has been tremendous progress in waste-water treatment at Boston Water and Sewer and MWRA facilities, there still is room for improvement. And we are learning that treatment can only do so much. Thus we need to pursue additional natural approaches.”

The collaboration with UMass-Boston began in two parts: First, the groups were connected through the Urban Harbors Institute, then doctoral student Lisa Greber met up with the Oyster Project membership at a scientific meeting. UMass Professor Anamarija Frankic, founder of the Green Boston Harbor project, had already begun looking at Malibu Bay with an eye toward restoring it to a cleaner/healthier and safer conditions. Last summer they monitored water quality in the Bay and reached out to contacts at Dorchester Yacht Club (DYC). Caring for the water is important to the club, which maintains a pump-out facility to ensure no waste from the boats enters the Bay and the Harbor.

DYC member Al Chouinard worked with the group to identify the optimal location for the oysters and shared his extensive knowledge of the Bay and its currents. There is deep soft silt on the bottom, so a permanent placement of oysters would need to be carefully orchestrated to ensure that the shellfish are placed on a firm surface where they would not be smothered. Silting was a problem in the Oyster Project’s initial initiative at the mouth of the Charles River.

Professor Frankic’s team is using these first oysters as a test case to determine if they can survive and grow in this environment. “Although we are starting with a very small sample, we will measure them, track their growth and mortality, and monitor water conditions, including temperature, oxygen, and salinity. These oysters are only an inch long, so we expect some mortality this winter as their small body mass makes them susceptible to death from hypothermia.”

But just as acorns grow to mighty oaks, it is hoped that this project will lead to bigger things. These oysters are only capable of filtering 6,000 gallons of water per day. But if they could be joined by another 100,000 oysters from Duxbury’s Island Creek Oyster Company, then they could be filtering millions of gallons of water per day.