The Massachusetts Oyster Project for Clean Water reintroduced around 150,000 oysters to Boston Harbor Oct. 25 in a step toward improving the water quality. MOP president Andrew Jay said the oysters can filter up to 30 gallons of water a day and will benefit the ecosystems as more than just a cleaning service. ‘Oysters are a key stone species for a healthy ecosystem in that they serve as homes or places of shelter for about 200 other types of sea life,’ he said. ‘Usually, there are three times the fish in areas with oysters than those without them.’ The organization worked closely with the Massachusetts Division of Marine Fisheries to make sure the location near the Constitution Marina posed minimal risk both the oysters and any adventurous Bostonians who might want to harvest them. ‘We chose the sight very carefully, so people are unlikely to be harvesting there,’ he said. In addition to the ‘No Harvesting’ signs posted all around the area, the site is not far from a state environmental police dock, which should prevent people from harvesting the oysters, Jay said. It is important to enforce such restrictions because there is a high chance of salmonella or other bacteria contamination in the oysters, Division of Marine Fisheries marine biologist Jeff Kennedy said. ‘There is always the temptation to just pick one up and eat it raw,’ he said. ‘With oysters and quahogs, you usually eat them raw, so the risk is much greater.’ The oysters become contaminated through their filtering process, which is the same process that allows them to clean areas of water, Kennedy said. Though the oyster cove is located at the mouth of the Charles River, the filtration will primarily focus on the harbor and will not affect the few swimming areas designated on the river, Jay said.