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MAPPING BURROWING SHRIMP AND SEAGRASS IN YAQUINA ESTUARY
Citation:
DEWITT, T. H. MAPPING BURROWING SHRIMP AND SEAGRASS IN YAQUINA ESTUARY. Presented at Pacific Estuarine Research Society annual meeting, Victoria, BC, CANADA, February 22 - 24, 2007.
Impact/Purpose:
Presentation
Description:
Burrowing shrimp and seagrasses create extensive intertidal and shallow subtidal habitats within Pacific NW estuaries. Maps of their populations are useful to inform estuarine managers of locations that deserve special consideration for conservation, and to inform oyster farmers of locations suitable for placing oysters so as to avoid interacting with the shrimp or seagrasses. Since burrowing shrimp are considered a pest to oyster aquaculture, mapping shrimp populations is useful for monitoring changes in shrimp populations on oyster beds, evaluating locations in oyster beds where shrimp densities need to be reduced, and for monitoring the efficacy of shrimp-control methods. Methods for surveying and mapping burrowing shrimp populations and seagrass populations in Pacific NW estuaries have been developed at the US EPA laboratory. Burrowing shrimp maps are based on rapid visual classification of shrimp burrows for species identity and burrow hole density, and species-specific relationships between burrow hole density and shrimp density. Application of this method to map shrimp populations in Yaquina Estuary (OR) will be presented. Several approaches for mapping seagrasses have been evaluated in our laboratory, including aerial photography, underwater video, and side scan sonar. A methodology utilizing side scan sonar and underwater video in combination was found to provide the most complete maps of eelgrass (Zostera marina) across the full depth range in which the plants occur. Application of this method for mapping seagrasses in Yaquina Estuary will be presented. These methods may be useful for mapping burrowing shrimp and seagrasses on or adjacent to oyster culture beds.