Wellfleet Bay Oyster Reef Habitat Restoration Project
The Wellfleet Bay Wildlife Sanctuary, one of Mass Audubon’s protected areas in Cape Cod, Massachusetts, initiated an oyster reef habitat restoration project on the intertidal flats of Lieutenant Island. This project was created to boost local populations of the wild American oyster (Crassostrea virginica) and to restore oyster reef habitat, which protects communities against increased storm surges, sea level rise, and coastal erosion. Less than a year after the oyster reefs were installed, winter ice floes destroyed the reefs.
The Wellfleet Bay Wildlife Sanctuary, with support from The Nature Conservancy and the National Oceanic and Atmospheric Administration, established the first oyster reef habitat restoration project in Massachusetts on the intertidal flats of southwest Lieutenant Island. Oyster reefs are three-dimensional habitats comprised of living and dead oysters, and serve multiple ecological functions. They improve water quality by filtering and removing nutrients, suspended sediments, and chemical contaminants; create habitat for other species, especially juvenile fish and crabs; and reduce bank erosion. This habitat type is among the most endangered in the ocean; approximately 85% of oyster reef habitat has been lost around the world. In Wellfleet Bay, oyster reefs have essentially disappeared, primarily as a result of pollution, overfishing, and disease. The Sanctuary sought to restore these reefs because they serve as natural coastal buffers that protect shorelines and keep coastal marshes intact by helping to break down wave energy before it reaches the shoreline––an especially important service with the likely increases in storm surges and sea level rise expected with climate change. The aims of this project were to boost wild American oyster populations and restore oyster reef habitat and the ecological services it provides to Wellfleet Bay.
The project was partially funded through a grant from NOAA’s Community-based Restoration Program and private donations. Project leaders experimented with different types of structures upon which oyster can seed and build a foundation over two acres of intertidal flats. Three different techniques were tested––oyster blocks, reef balls, and shell culch––and monitoring put in place to measure oyster population dynamics, oyster disease, and the use of the area by birds, invertebrates, and fish. The Massachusetts Division of Marine Fisheries, Cape Cod Extension program for Barnstable County, New England Aquarium, and Town of Wellfleet provided project assistance.
The project team identified that the project would be a “success” when a high density and survival of oysters was reached across the area and growing substrates no longer need to be added to sustain the reef. Initial results indicated that ~250,000 oysters were successfully growing on the reef between June 2009 and January 2010. However, winter ice floes then scoured the reef, reducing the number of oysters to ~60,000 and destroying ~50% of the reef balls and the majority of the shell culch. This event highlighted an important lesson learned––the need to install oyster reef habitat in areas more protected from these types of winter events.
Outcomes and Conclusions
The oyster reef habitat restoration project in the intertidal flats of Lieutenant Island is now defunct. Funding for the project was restricted to this particular site and, given the unanticipated impact of winter ice floes on the project’s success, Mass Audubon opted not to install new reefs in this location. Mass Audubon is seeking funding for additional oyster reef habitat restoration projects in more protected areas.
Gregg, R. M. (2020). Wellfleet Bay Oyster Reef Habitat Restoration Project [Case study on a project of the Wellfleet Bay Wildlife Sanctuary]. Version 2.0. Product of EcoAdapt's State of Adaptation Program. (Last updated June 2020)