Collaborative Research: Climate Change and Upwelling -- Comparative Analysis of Current & Future Responses of the California and Benguela Ecosystems

在北美洲、南美洲、非洲和伊比利亚的西海岸，赤道沿岸的风将营养丰富的水域带到阳光明媚的海洋表面，刺激浮游植物大量繁殖，支持强大、丰富和多样化的生态系统。这个过程被称为“上升流”。由于上升流是由风驱动的，而风与大气条件有关，因此上升流极易受到气候变化的影响。然而，气候变化对上升流和生物的潜在影响在很大程度上仍然不确定。在美国西海岸外的加利福尼亚州洋流上升系统的早期研究中，研究人员发现，上升流以不同的冬季和夏季“模式”发生，对生物学有不同的影响。在这个项目中，将分析南非和纳米比亚附近本格拉洋流系统的海洋和大气数据，以寻找类似的季节模式和与生态系统的关系。对这两个上升流系统的比较将使研究人员能够调查之前关于区域气候对生物影响的发现是否适用于全球范围，并考虑这些系统未来可能会发生什么变化。该项目将促进来自南非、纳米比亚和美国的研究人员之间的合作，整合来自所有国家的年轻和资深科学家团队，并为他们提供在职业生涯早期进行广泛科学合成的机会。该项目将对加州洋流(CCS)和本格拉洋流系统(BCS)的气候强迫和生物响应进行比较分析，这两个上升流系统具有最相似的大气和海洋条件、海鸟人口统计以及低(叶绿素)和中(饲料鱼)营养数据的时间序列。该项目将确定生态系统的变化是否可以归因于区域或全球气候过程。将编制BCS(深水鳕鱼)鱼类生长-增量年表，作为上层营养鱼类生长的指标，并与CCS制定的岩鱼生长年表进行比较。中等营养水平的鱼类丰度将被模拟为猎物可获得性的指数，以便将气候和上层营养水平参数结合起来。将从全球观测和再分析数据集以及地球系统气候变化模型预测中分析海洋和大气数据。该项目将解决以下问题：1)BCS中的季节性上升流模式(冬季和夏季)是否与CCS中相同？2)上升流模式是由相似或相反的大气强迫机制强迫的吗？3)在CCS和BCS内部和之间是否有证据表明中营养鱼类、上层营养鱼类和海鸟(以及在哪些滞后时)之间存在一致性/协变性？4)在各种气候变化情景下，导致上涌有利风的大气压力系统的位置和幅度是否会在生态系统之间发生一致的变化？5)渔业和野生动物管理对气候变化中上升流的季节性和空间分布的可变性有何影响？

Along the west coasts of North and South America, Africa, and Iberia, alongshore equatorward winds bring nutrient-rich waters to the sunlit surface of the ocean, stimulating phytoplankton blooms that support robust, rich and diverse ecosystems. This process is known as "upwelling". Because upwelling is driven by winds, and winds are related to atmospheric conditions, upwelling is highly vulnerable to the effects of climate change. However, the potential impacts of climate change on upwelling and biology remain largely uncertain. In earlier work in the California Current upwelling system, off the west coast of the U.S.A, researchers found that upwelling occurs in distinct winter and summer "modes" that have different impacts on biology. In this project, oceanographic and atmospheric data from the Benguela Current system, off South Africa and Namibia, will be analyzed for similar seasonal patterns and relationships with the ecosystem. Comparisons between these two upwelling systems will allow researchers to investigate if previous findings of regional climate impacts on biology are applicable at a global scale and consider how these systems may change in the future. The project will facilitate collaboration between researchers from South Africa, Namibia, and the U.S., integrating a team of young and senior scientists from all countries and providing them with opportunities for broad-scale scientific synthesis early in their careers.This project will be a comparative analyses of climate forcing and biological responses in the California Current (CCS) and Benguela Current systems (BCS), the two upwelling systems with the most similar time series of atmospheric and oceanographic conditions, seabird demography, and lower (chlorophyll) and mid (forage fish) trophic data. The project will determine whether changes in the ecosystems can be attributed to regional or global climate processes. Growth-increment chronologies from fish in the BCS (deep-water hake) will be developed as indicators of upper-trophic fish growth, and compared to rockfish growth chronologies developed in the CCS. Mid-trophic level fish abundance will be modeled as indices of prey availability for integration between climate and upper-trophic-level parameters. Oceanographic and atmospheric data will be analyzed from global observational and reanalysis data sets, as well as from earth system model projections of climate change. The project will address the following questions: 1) are seasonal upwelling modes (winter and summer) discernible in the BCS as they are in the CCS? 2) are upwelling modes forced by similar or contrasting atmospheric forcing mechanisms? 3) is there evidence of coherence/covariance among mid-trophic fish, upper-trophic fish, and seabirds (and at which lags) within and between the CCS and BCS? 4) will the positioning and amplitude of the atmospheric pressure systems that result in upwelling-favorable winds change coherently between ecosystems under various climate-change scenarios? and 5) what are the fisheries and wildlife management implications for variability in the seasonality and spatial distribution of upwelling in a changing climate?