Northwest Fisheries Science Center

Newportal Blog

A gateway to oceanographic adventures from the Newport Line and beyond

Blog on ocean conditions along the Newport Line and the northern CA Current.

Physical Spring Transition?...Not Quite Yet

By Jennifer Fisher
April 7, 2017

The Oregon coast is presently being hit by strong southerly winds and high seas. This morning, winds have been blowing steadily out of the south at 45 miles per hour with gusts up to 63 miles per hour, signaling that the physical spring transition has not yet occurred off Newport.

The physical spring transition is marked by the change from southerly winds that brings downwelling and storms to our coast during winter to northwesterly winds that drives upwelling circulation along our coast. The onset of upwelling generally occurs around April 15, but at times it can occur earlier or later. Upwelling brings cold nutrient rich water to the upper ocean. The nutrient rich water interacts with sunlight and phytoplankton blooms occur, thereby fueling productivity along our coast.

Along with the winds, the coastal currents also change from primarily poleward during the winter to equatorward during the summer delivering different suites of zooplankton to the Oregon shelf, which we call the biological spring transition. During the upwelling season, the zooplankton are normally comprised of lipid rich copepods that fuel a productive food chain for upper trophic levels. However, over the past three years during the Warm Blob and El Niño, this biological spring transition did not occur, and lipid rich copepods have been absent.

We are watching to see when the physical spring transition occurs and if this year the copepod community will finally change back to a more ‘normal’ summer community of lipid rich zooplankton. As soon as the seas settle, we will head out to sample and report back on what we find.


Tagged: NH Line, Warm Blob, El Niño

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