Characterizing the Habitat Function of Bivalve Aquaculture Using Underwater Video

An egret sits on bags of oysters.
WOPA110201_D101 An egret stands on one of the 23,000 bags of oysters that line the edge of a mud flat on Mobile Bay in Alabama. Volunteers will spend the weekend moving the bags—each weighing approximately 10 pounds—across the mud flat at low tide in an assembly line fashion to create the foundation for oyster reefs to grow, ultimately protecting 1,000 feet of shoreline to help restore the Gulf of Mexico. During the course of this weekend event, volunteers will work alongside Conservancy scientists and partners to construct the first quarter-mile of oyster reef as part of the 100-1000: Restore Coastal Alabama project. Spearheaded by the Nature Conservancy, Alabama Coastal Foundation, Mobile Baykeeper and the Ocean Foundation, the 100-1000 project aims to build 100 miles of oyster reefs and grow 1,000 acres of marsh and sea grass. © © Erika Nortemann/TNC

The habitat function of shellfish aquaculture is not yet well understood, in part due to difficulties in data collection using traditional methods. In this study, underwater video was used to observe fish and crab species’ affiliations with cultured Pacific oyster Crassostrea gigas and Manila clam Venerupis philippinarum aquaculture sites in comparison to uncultured reference sediment and eelgrass habitats.

Sites were monitored in 9 locations across 3 regions of Puget Sound, Washington, USA, in the summers of 2017 and 2018. Species composition varied between aquaculture and non-aquaculture habitats in 2 of the 3 regions studied. Species diversity and richness in aquaculture habitats varied regionally, relative to reference habitats. Pelagic species were more abundant in aquaculture and reference sites that had vertical structure, but abundances of demersal and benthic species on aquaculture habitat relative to reference sites varied regionally.

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