An ongoing four-year project of the Westport River Watershed Alliance (WRWA) is an initiative to reverse the nitrification of Cockeast Pond by planting half a million oysters in a fraction of the pond’s area.
Residents of Westport have long been familiar with oysters as source of food–and employment–but oysters might also be capable of solving a crippling environmental problem. It’s an exciting and new solution to a well-known problem. Pollution from human activity emits nitrogen via surface runoff, human and animal waste discharge, and emissions from combustion. Surface runoff, the flow of excess waters over Earth’s surface, is a particularly significant problem. Many farmers and homeowners treat their soil with nitrate-rich fertilizers, pesticides, and more, and when rainwater soaks through this soil it carries nitrates with it wherever it’s going.
High levels of nitrogen in bodies of water cultivate the growth of algal blooms. Algae feed on nitrates and phosphates. When an excess of these nutrients appears, algae growth explodes. When algae die, their decomposition consumes oxygen. If there are enough algae, this process can deplete a body of water of oxygen. Since marine animals require oxygen to survive, algal blooms kill off fish and shellfish, as well as more complex species of plants that process nitrogen differently than algae. In addition, harmful bacteria can thrive as a result of algal blooms and sicken humans and animals that enter the infected body of water. Beaches have often closed off as a result of algae blooms.
How do oysters fit into this? For decades, scientists have known that oysters are able to filter water and use its elements to build tissue and store waste ingredients in surrounding sediment. Microbes break down this sediment and release nitrogen into the water, where it emerges into the atmosphere as harmless gas in a process known as denitrification.
So what would happen if someone put 500,000 oysters in a pond plagued by algal blooms? This was the question asked by researchers from the UMass Dartmouth School for Marine Science and Technology (SMAST), which has partnered with WRWA to test a theory that oysters could bring the nitrogen levels of Cockeast Pond under control. After 30,000 oysters passed a baseline survivability test in the spring of 2016, the EPA awarded the SMAST researchers over half a million dollars to take the next, much larger step.
If this method of denitrification is successful, it will mean much more than the survival of Cockeast Pond. “Addressing the nitrogen problem along the South Coast, Cape Cod and the South Shore will cost billions of dollars if we only consider traditional strategies such as bigger wastewater treatment plants and more sewer lines,” reported Dr. Brian Howes from UMass Dartmouth. “We just don’t have the time or money for that course. It is, therefore, imperative that we find soft solutions that leverage nature, in this case the oyster, to make progress.” Success in the case of Cockeast Pond could lead to billions of dollars saved down the road if this method were applied all over the country and even the world.
Nothing is certain, but as of fall 2017, things are looking up.