School of Marine and Atmospheric Sciences, Stony Brook University, Stony Brook, NY 11794, USA.
Proc Natl Acad Sci U S A. 2012 Nov 20;109(47):19315-20. doi: 10.1073/pnas.1207514109. Epub 2012 Oct 15.
Over the last few decades, rising greenhouse gas emissions have promoted poleward expansion of the large-scale atmospheric Hadley circulation that dominates the Tropics, thereby affecting behavior of the Intertropical Convergence Zone (ITCZ) and North Atlantic Oscillation (NAO). Expression of these changes in tropical marine ecosystems is poorly understood because of sparse observational datasets. We link contemporary ecological changes in the southern Caribbean Sea to global climate change indices. Monthly observations from the CARIACO Ocean Time-Series between 1996 and 2010 document significant decadal scale trends, including a net sea surface temperature (SST) rise of ∼1.0 ± 0.14 °C (±SE), intensified stratification, reduced delivery of upwelled nutrients to surface waters, and diminished phytoplankton bloom intensities evident as overall declines in chlorophyll a concentrations (ΔChla = -2.8 ± 0.5%⋅y(-1)) and net primary production (ΔNPP = -1.5 ± 0.3%⋅y(-1)). Additionally, phytoplankton taxon dominance shifted from diatoms, dinoflagellates, and coccolithophorids to smaller taxa after 2004, whereas mesozooplankton biomass increased and commercial landings of planktivorous sardines collapsed. Collectively, our results reveal an ecological state change in this planktonic system. The weakening trend in Trade Winds (-1.9 ± 0.3%⋅y(-1)) and dependent local variables are largely explained by trends in two climatic indices, namely the northward migration of the Azores High pressure center (descending branch of Hadley cell) by 1.12 ± 0.42°N latitude and the northeasterly progression of the ITCZ Atlantic centroid (ascending branch of Hadley cell), the March position of which shifted by about 800 km between 1996 and 2009.
在过去几十年中，温室气体排放的增加促进了主导热带地区的大规模大气哈德利环流的极向扩张，从而影响了热带辐合带（ITCZ）和北大西洋涛动（NAO）的行为。由于观测数据集稀疏，因此对热带海洋生态系统中这些变化的表现了解甚少。我们将加勒比海南部海洋的当代生态变化与全球气候变化指数联系起来。1996 年至 2010 年间，CARIACO 海洋时间序列的每月观测记录显示出显著的十年尺度趋势，包括海面温度（SST）净升高约 1.0 ± 0.14°C（±SE），分层加剧，上升流输送到表层水域的营养物质减少，以及浮游植物大量繁殖的强度减弱，表现为总叶绿素 a 浓度（ΔChla = -2.8 ± 0.5%⋅y(-1)）和净初级生产力（ΔNPP = -1.5 ± 0.3%⋅y(-1)）的整体下降。此外，浮游植物分类群的优势从硅藻、甲藻和有孔虫转变为 2004 年后较小的分类群，而中型浮游动物生物量增加，食浮游动物沙丁鱼的商业捕捞量崩溃。总的来说，我们的结果揭示了这个浮游系统的生态状态变化。信风减弱的趋势（-1.9 ± 0.3%⋅y(-1)）和相关的局部变量主要由两个气候指数的趋势来解释，即亚速尔高压中心（哈德利环流的下降分支）向北迁移 1.12 ± 0.42°N 纬度，以及热带辐合带大西洋质心的东北推进（哈德利环流的上升分支），1996 年至 2009 年期间，其 3 月位置向东北方向移动了约 800 公里。
