Upwelling is a process that draws deep salty water, rich in nutrients up to the surface replacing warmer waters that have been pushed offshore by prevailing winds. In upwelling regions these nutrients can be utilized by phytoplankton with CO2 and energy from the sun to produce organic compounds through photosynthesis. The upwelling regions support a very high level of primary productivity and fix carbon from CO2 in the atmosphere. Upwelling regions are extremely productive due to this constant influx of nutrients and resulting primary production. Primary production by phytoplankton forms the base of the food chain which supports higher the trophic levels critical to marine ecosystems. These upwelling regions support some of the world’s largest fisheries such as the sardine fishery off the coast of Peru and Chile.
Upwelling regions influence more than productivity in Oregon. They initiate hypoxic zones where phytoplankton produced by high primary productivity sink to the sea floor, decompose by bacterial action, and remove virtually all oxygen from the water. This kills all organisms that rely on oxygen dissolved in the water. Upwelling also influences the recruitment of fish and invertebrates. When fish and invertebrates reproduce, their larvae can drift with ocean currents for up to several months, potentially traveling great distances. PISCO oceanographers are documenting a number of near shore physical processes near shore that contribute to larval movement within Monterey Bay. For example, they have found that the upwelling shadow front may be the related to the recruitment of fish and barnacle larvae along the coastline. PISCO also is uncovering links between physical oceanography and biological processes on longer time scales, including multiyear effects of El Niño on fish replenishment