Barth John A, Menge Bruce A, Lubchenco Jane, Chan Francis, Bane John M, Kirincich Anthony R, McManus Margaret A, Nielsen Karina J, Pierce Stephen D, Washburn Libe
College of Oceanic and Atmospheric Sciences and Department of Zoology, Oregon State University, Corvallis, OR 97331, USA.
Proc Natl Acad Sci U S A. 2007 Mar 6;104(10):3719-24. doi: 10.1073/pnas.0700462104. Epub 2007 Feb 27.
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 degrees 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.
风力驱动的沿海洋流上升流为海岸附近的透光层提供养分。这些养分促进了浮游植物的生长，而浮游植物是高产的沿海海洋生态系统的基础[保利 D，克里斯滕森 V（1995年）《自然》374：255 - 257]。由于陆架水域的养分供应和浮游植物生物量对上升流驱动的环流变化高度敏感，上升流时间和强度的变化可能会改变通过海洋食物网的基本养分和碳通量。我们展示了2005年加利福尼亚州北部大海洋生态系统春季向有利于上升流的风应力转变延迟1个月是如何导致众多异常情况的：温水、低养分水平、低初级生产力以及潮间带岩石生物前所未有的低补充量。这种延迟与伴随急流向南移动的20至40天的风振荡有关。在俄勒冈州外海的上升流季节早期（5月至7月），累积的有利于上升流的风应力是20年来最低的，近岸表层水温比正常平均高2摄氏度，冲浪区叶绿素a和养分分别比正常水平低50%和30%，贻贝和藤壶的补充量密度分别降低了83%和66%。早期上升流延迟和后期上升流增强与全球变暖对沿海上升流区域影响的预测一致。
