Distribution, Abundance, and Habitat Associations of a Large Bivalve (Panopea generosa) in a Eutrophic Fjord Estuary

ABSTRACT Marine bivalves are important ecosystem constituents and frequently support valuable fisheries. In many nearshoreareas, human disturbance—including declining habitat and water quality—can affect the distribution and abundance of bivalve populations, and complicate ecosystem and fishery managementassessments. Infaunal bivalves, in particular, are frequently cryptic and difficult to detect; thus, assessing potential impacts on their populations requires suitable, scalable methods for estimating abundance and distribution. In this study, population size of a common benthic bivalve (the geoduck Panopea generosa) is estimated with a Bayesian habitat-based model fit to scuba and tethered camera data in Hood Canal, a fjordbasin in Washington state. Densities declined more than two orders of magnitude along a north—south gradient, concomitant with patterns of deepwater dissolved oxygen, and intensity and duration of seasonal hypoxia. Across the basin, geoduckswere most abundant in loose, unconsolidat...