Physical processes that enhance nutrient transport and primary productivity in the coastal and open ocean of the subarctic NE Pacific

Damming of the Columbia River and human uses of its waters have resulted in more winter and less summer discharge of fresh water and dissolved Si. Coastal currents in this area flow north in winter and south in summer. As a consequence, there has been a net temporal change in Si inputs to the ocean since the mid 1970s, with about 4×109 mol more Si flowing north in winter and 9×109 mol less Si flowing south in summer compared with the early 1900s. Since silicate limits diatom growth and diatoms are responsible for most carbon export in phytoplankton, implications for ocean productivity are significant.