过去20年太平洋反气旋迁移和洪保德上升流生态系统巴肯效应引起的沿海海洋生产力的空间变化
Spatial shifts in productivity of the coastal ocean over the past two decades induced by migration of the Pacific Anticyclone and Bakun effect in the Humboldt Upwelling Ecosystem
摘要：
上升流有利风的增强和向极扩展被预测为对人类活动引起的全球气候变化的响应，并且最近在世界上大多数东边界上升流生态系统中被记录。为了确定这些过程是如何影响近岸海洋栖息地的，特别是洪堡上升流生态系统（HUE）初级生产力的长期趋势，我们分析了海平面气压，风应力，海面和大气地面温度的时间序列，叶绿素a，作为初级生产力的代理，沿26° - 36° S。我们表明，气候引起的初级生产力的趋势是高度异质性的整个地区。一方面，南太平洋反气旋（SPA）的向极迁移导致了约1000年至2000年春季上升流风的减少。南纬30°和34°，并在南部加强。在智利中部的这一地区，风的减少使海面温度略有增加，并使表面叶绿素a显著和季节性广泛减少。在30° S以北，近岸上升流风显著增强，SST显著降低，叶绿素a浓度显著升高。我们表明，这种上升流驱动的沿海生产力的增加可能是由过去20年来发生在30° S以北的海陆压力梯度增加（巴肯效应）造成的。因此，高营养利用率沿线的气候驱动因素导致海洋条件和初级生产力出现截然不同的趋势，这可能对沿海中上层和底栖生态系统产生深远影响，并导致主要渔业在地理上的迁移。
英文摘要：
Intensification and poleward expansion of upwelling favourable winds have been predicted as a response to anthropogenic global climate change and have recently been documented in most Eastern Boundary Upwelling Ecosystems of the world. To identify how these processes are impacting nearshore oceanographic habitats and, especially, long term trends of primary productivity in the Humboldt Upwelling Ecosystem (HUE), we analysed time series of sea level pressure, wind stress, sea surface and atmospheric surface temperatures, and Chlorophyll-a, as a proxy for primary productivity, along 26° - 36° S. We show that climate induced trends in primary productivity are highly heterogeneous across the region. On the one hand, the well documented poleward migration of the South Pacific Anticyclone (SPA) has led to decreased spring upwelling winds in the region between ca. 30° and 34° S, and to their intensification to the south. Decreased winds have produced slight increases in sea surface temperature and a pronounced and meridionally extensive decrease in surface Chlorophyll-a in this region of central Chile. To the north of 30° S, significant increases in upwelling winds, decreased SST, and enhanced Chlorophyll-a concentration are observed in the nearshore. We show that this increased in upwelling driven coastal productivity is probably produced by the increased land-sea pressure gradients (Bakun's effect) that have occurred over the past two decades north of 30° S. Thus, climate drivers along the HUE are inducing contrasting trends in oceanographic conditions and primary productivity, which can have far-reaching consequences for coastal pelagic and benthic ecosystems and lead to geographic displacements of the major fisheries.
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