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Oceans and Coasts

Shellfish Reefs at Risk: Critical Marine Habitats

Native bivalve shellfish provide a variety of ecologically and economically valuable services. As “ecosystem engineers” shellfish influence the environment around them in ways that benefit other species – and therefore benefit people and our economy.

Shellfish reefs and beds around the world:

  • Filter suspended particles from the water column, increasing water clarity, which in turn enables seagrass growth and reduces the likelihood of harmful algal blooms.
  • Remove excess nutrients from coastal bays through denitrification.
  • Serve as natural coastal buffers, absorbing wave energy and reducing erosion from boat wakes, sea level rise and storms.
  • Provide nursery habitat for fish that are valuable to coastal economies.
  • Contribute to tourism and recreation by improving adjacent water quality and providing fish habitats, resulting in more desirable areas for tourists to visit.

Recognition of the “ecosystem” services provided by other habitats such as coral reefs and mangroves has resulted in greater protection for those habitats and management with multiple human values in mind. Oyster reefs should also be managed in ways that consider the value of these systems to surrounding coastal areas, beyond harvests. Just as important, perhaps, is the need to develop opportunities to support, pay or trade for these services from shellfish reefs.

Given the public and private funds being invested in reducing nitrogen pollution from land-based sources, more natural solutions, such as nutrient trading, could receive significant new funds. In Europe costs to build a sewage treatment were deferred by the supporting the growth of mussels to filter those waters.

In many places, walls and jetties are built to defend coastlines from erosion; in many places revitalized reefs could provide this protection and offer many additional services as well.

Shellfish and People: More than Fisheries
  • Shellfish have supported civilizations for millennia from Romans to railroad workers in California in the 1800s.
  • In 1864 alone, 700 million European flat oysters (Ostrea edulis) were consumed in London, employing up to 120,000 men in Britain to dredge oysters.
  • Shell piles in the southwest of France contain over 1 trillion shells apiece, underscoring both the productivity of the native species and the scale of harvest.
  • In the 1870s, intertidal reefs of the eastern oyster (Crassostrea virginica) extended for miles along the main axis of the James River in Chesapeake Bay but had largely disappeared by the 1940s.
  • Roads in many coastal areas, including around Matagorda Bay, Texas, were often paved using oyster shells.

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