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Comparison of the structure of lower and upper estuary food webs for Yaquina Bay (OR)
Citation:
DEWITT, T. H., S. R. Pacella, C. FOLGER, AND P. M. ELDRIDGE. Comparison of the structure of lower and upper estuary food webs for Yaquina Bay (OR). Presented at Pacific Estuarine Research Society Meeting, Astoria, OR, March 03 - 05, 2011.
Impact/Purpose:
Food web models can be used to estimate effects of water quality, habitat distribution or species loss on productivity, carbon flow and ecosystem service production in Pacific NW estuaries.
Description:
Food web models can be used to estimate effects of water quality, habitat distribution or species loss on productivity, carbon flow and ecosystem service production in Pacific NW estuaries. Here we present a comparison of floral and faunal data used to parameterize food web models for the lower (polyhaline) and upper (mesohaline) reaches of Yaquina estuary. The data were compiled from our own studies (habitat area, benthic infauna distribution, benthic micro- and macroalgal distribution, stable isotope signatures of dominant biota), other studies from Yaquina Bay (water quality parameters; primary production rates; phytoplankton, zooplankton, nekton, and bird distribution), or studies from other estuaries in the region (phytoplankton productivity; meiofauna). On a per unit area basis, abundance, biomass, diversity and productivity of flora and fauna were substantially higher in the lower estuary. Green macroalgae was the dominant primary producer in the lower estuary, while phytoplankton was dominant in the upper. Net primary production was 10x higher in the lower estuary. Benthic invertebrates dominated the biomass among all faunal guilds in both reaches, while the biomass of nekton and birds was 100x smaller than infauna. Suspension feeders were the dominant faunal guild in the lower estuary and suspension-deposit feeders were dominant in the upper estuary. Mega-infauna (burrowing shrimp, bivalves) comprised most of the infaunal biomass in both reaches, although they constituted only a tiny fraction of the abundance. Nekton in both reaches was dominated by the same species (Dungeness crabs, bay shrimp, English sole, staghorn sculpins, and shiner surfperch), but production was 10x higher in the lower estuary. Bird productivity in the lower estuary (dominated by gulls, herons, cormorants and ducks) was 5x higher than in the upper estuary (dominated by cormorants, herons, and Canada geese). The greater productivity of the lower estuary was probably driven by the tidal advection of oceanic plankton that supported suspension feeders and clearer oceanic water that permitted greater benthic micro- and macroalgal growth.