A critical precursor to restoration has been to establish secure man- agement to prevent degradation or loss of restored areas. This has been achieved though the establishment of legal sanctuaries, and through private ownership or leasing of intertidal and subtidal lands. A broad range of restoration techniques have been developed and tested. Where recovery is limited by habitat availability (young oyster “spat” need to settle on hard substrates), restoration techniques fo- cus on the provision of “cultch”, or areas of hard bottom. Elsewhere, where recruitment is a limiting factor, juveniles need to be returned to the environment. In both cases experimental work has identified the importance of vertical relief, hydrodynamics, and a wider understand- ing of meta-populations in restoring reefs to levels that are self-sus- taining and ecologically significant. Systematic approaches, based on
the best science, are leading to successful restoration across the country, such as the restoration by the US Army Corps of Engineers of over 297ha of oyster reef since 2001 within the Chesapeake Bay, North America’s largest estuary. Increasingly ambitious programs are being established; the recent Chesapeake Bay Executive Order (2009) resulted in the goal of restoring oyster populations in 20 of 35–40 candidate tributaries of the Chesapeake by 2025. This is an immense challenge given that oyster reefs were close to ecologi- cal extinction in this Bay just a few years ago.
Source: Philine zu Ermgassen and Mark Spalding, The Nature Conservancy and Cambridge University, Personal communication, 2010. Photo credits: Mark Spalding.
benefits of successful oyster restoration on the Eastern Shore. Along the South Eastern United States, fin-fish and decapod fisheries benefits derived from restored oyster reefs have been estimated at 2.6kg/10m2/year, while in Louisiana and North Carolina restored intertidal reefs have locally reduced the rate of shoreline retreat. Work is in process to determine how such benefits may vary between locations.
The success of projects such as those on the Eastern Shore of Virginia provided a major impetus for encouraging the US government to provide USD 150 million in a 2009 national stimulus package for large-scale restoration projects, includ- ing several other oyster reef projects. More science is needed, notably to gain a better understanding of the final targets for restoration. How much restoration will be needed to achieve measurable and useful levels of water purification or increased fisheries production? Where and how should reefs be arrayed to maximize coastal protection benefits? Enough is already known, however, for the work to commence, and the research is running in parallel, enabling benefits to be derived even as understanding of the complex ecological story is refined.
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