A novel method for determination of aragonite saturation state on the continental shelf of central Oregon using multi-parameter relationships with hydrographic data

Abstract

We developed a multiple linear regression model to ustly determine aragonite saturation state (arag) from observations of temperature and oxygen (R2 = 0.987, RMS error 0.053), using data collected in the Pacific Northwest region in late May 2007. The seasonal evolution of arag near central Oregon was evaluated by applying the regression model to a monthly (winter)/bi-weekly (summer) watercolumn hydrographic time-series collected over the shelf and slope in 2007. The arag predicted by the regression model was less than 1, the thermodynamic calcification/dissolution threshold, over shelf/slope bottom waters throughout the entire 2007 upwelling season (May-November), with the arag = 1 horizon shoaling to 30 m by late summer. The persistence of water with arag < 1 on the continental shelf has not been previously noted and could have notable ecological consequences for benthic and pelagic calcifying organisms such as mussels, oysters, abalone, echinoderms, and pteropods. Copyright 2009 by the American Geophysical Union.