Wind-driven coastal ocean upwelling supplies nutrients to the
euphotic zone near the coast. Nutrients fuel the growth of phytoplankton,
the base of a very productive coastal marine ecosystem
[Pauly D, Christensen V (1995) Nature 374:255–257]. Because
nutrient supply and phytoplankton biomass in shelf waters are
highly sensitive to variation in upwelling-driven circulation, shifts
in the timing and strength of upwelling may alter basic nutrient
and carbon fluxes through marine food webs. We show how a
1-month delay in the 2005 spring transition to upwelling-favorable
wind stress in the northern California Current Large Marine Ecosystem
resulted in numerous anomalies: warm water, low nutrient
levels, low primary productivity, and an unprecedented low recruitment
of rocky intertidal organisms. The delay was associated
with 20- to 40-day wind oscillations accompanying a southward
shift of the jet stream. Early in the upwelling season (May–July) off
Oregon, the cumulative upwelling-favorable wind stress was the
lowest in 20 years, nearshore surface waters averaged 2°C warmer
than normal, surf-zone chlorophyll-a and nutrients were 50% and
30% less than normal, respectively, and densities of recruits of
mussels and barnacles were reduced by 83% and 66%, respectively.
Delayed early-season upwelling and stronger late-season
upwelling are consistent with predictions of the influence of global
warming on coastal upwelling regions.Keywords: coastal ocean upwelling, coastal marine ecosystems, marine ecology, climate variabilit
