Can Bivalve Habitat Restoration Improve Degraded Estuaries

Abstract Bivalve habitats were once a dominant ecosystem in temperate and subtropical estuaries worldwide. While bivalve habitats are greatly reduced from their former abundance, remnant, and restored populations have been shown to provide a suite of important ecosystems services including improving water quality, coastal protection, and providing fisheries nursery habitat, in addition to providing a direct food value. Although it is unlikely that bivalve habitats can be brought back to their former abundance in most locations, bivalve restoration has been shown to be possible at large scale if the drivers of decline have been addressed. Restoring bivalve habitats can improve the health of estuaries, but restoration activities need to be supplemented with improved management practices, including in the surrounding catchments. Taking an estuary-wide approach to restoration, with bivalve habitat restoration complementing the restoration of other habitat types such as seagrasses, salt marshes, and mangroves is likely to yield both greater ecosystem benefits and may result in positive feedbacks resulting in greater restoration success of complimentary habitats. Motivation for bivalve and other coastal habitat restoration has moved beyond simply restoring an imperiled ecosystem and its biodiversity, to restoring food security, local employment, green engineering, shoreline protection, and nutrient trading. In the future it is likely that innovative engineering solutions will improve the success and value of bivalve habitat restoration. In addition to restoring natural bivalve habitats and the benefits that they bring to estuaries and the people who depend on them, novel solutions to improving estuary health and food security should be considered. There are likely to be benefits from using bivalve aquaculture as a tool for ecosystem modification (e.g., harnessing the filtering power of bivalves at high densities to improve local water quality) and creating green engineering solutions that include living elements such as bivalves to protect shorelines.