Aquatic Sciences Meeting, Albuquerque 2001

CS40 Nutrients, Primary Production, and Aquatic Ecosystems

Date: Wednesday, February 14, 2001, Time: 2:15:00 PM

Location: La Cienega

Newton, J, A, Washington Dept. Ecology/Univ. Washington, Olympia, USA, newton@ocean.washington.edu

Ehinger, W, , Washington Dept Ecology, Olympia, USA,

Siegel, E, , Washington Dept Ecology, Olympia, USA,

Bos, J, , Washington Dept Ecology, Olympia, USA,

Nakata, K, , Washington Dept. Ecology, Olympia, USA,

Hickey, B, , University of Washington, Seattle, USA,

CONTROL OF NORTHWEST COAST ESTUARINE PRIMARY PRODUCTION BY THE SUPPLY OF OCEANIC NITROGEN

Three years of carbon-uptake experiments in the productive coastal estuary, Willapa Bay, Washington, reveal that primary productivity is limited by nitrogenous nutrients during the growing season, March-October. Importation of oceanic water during coastal upwelling events appears to be the major source of nitrogen to the estuary. Riverine nitrogen loads are significant October through April only. The oceanic supply of nitrogen is influenced by a combination of the upwelling intensity and the depth of the oceanic mixed layer. Climate variation appears to exert substantial influence on both factors, and thus is an important determinant of coastal productivity. The data from growing seasons following the 1998 El Nino and 1999 La Nina demonstrate this relation. We have derived a multiple linear regression equation to predict primary production in Willapa Bay with a high r2 value (0.97). The dependent variables are chlorophyll a, PAR, and NOAA's Bakun Upwelling Index. The relation is important because all three variables can be monitored remotely, making now-casting of primary production in Willapa Bay possible. The applicability of the equation to other Pacific coast locations will be discussed.

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Aquatic Sciences Meeting, Albuquerque 2001

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