Estuary-enhanced upwelling of marine nutrients fuels coastal productivity in the U.S. Pacific Northwest

TitleEstuary-enhanced upwelling of marine nutrients fuels coastal productivity in the U.S. Pacific Northwest
Publication TypeJournal Article
Year of Publication2014
AuthorsDavis K.A, Banas N.S, Giddings S.N, Siedlecki S.A, MacCready P., Lessard E.J, Kudela R.M, Hickey B.M
JournalJournal of Geophysical Research-Oceans
Volume119
Pagination8778-8799
Date Published2014/12
Type of ArticleArticle
ISBN Number2169-9275
Accession NumberWOS:000348452800032
Keywordsbritish-columbia; california current system; carbon budget; Columbia River; columbia river plume; continental-shelf; eddy region; estuarine circulation; juan-de-fuca; nitrogen; of Juan de Fuca; organic-matter; Pacific Northwest; Primary productivity; strait; surface waters; vancouver island
Abstract

The Pacific Northwest (PNW) shelf is the most biologically productive region in the California Current System. A coupled physical-biogeochemical model is used to investigate the influence of freshwater inputs on the productivity of PNW shelf waters using realistic hindcasts and model experiments that omit outflow from the Columbia River and Strait of Juan de Fuca (outlet for the Salish Sea estuary). Outflow from the Strait represents a critical source of nitrogen to the PNW shelf-accounting for almost half of the primary productivity on the Vancouver Island shelf, a third of productivity on the Washington shelf, and a fifth of productivity on the Oregon shelf during the upwelling season. The Columbia River has regional effects on the redistribution of phytoplankton, but does not affect PNW productivity as strongly as does the Salish Sea. A regional nutrient budget shows that nitrogen exiting the Strait is almost entirely (98%) of ocean-originupwelled into the Strait at depth, mixed into surface waters by tidal mixing, and returned to the coastal ocean. From the standpoint of nitrogen availability in the coastal euphotic zone, the estuarine circulation driven by freshwater inputs to the Salish Sea is more important than the supply of terrigenous nitrogen by rivers. Nitrogen-rich surface waters exiting the Strait follow two primary pathwaysto the northwest in the Vancouver Island Coastal Current and southward toward the Washington and Oregon shelves. Nitrogen flux from the Juan de Fuca Strait and Eddy Region to these shelves is comparable to flux from local wind-driven upwelling.

DOI10.1002/2014jc010248
Short TitleJ Geophys Res-Oceans
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