Collaborative Research: Southern Ocean Iron Experiment (SOFeX): Mesoscale Iron Fertilization Effects on Plankton Community Structure, Growth and Zooplankton Grazing

南大洋是了解海洋在全球碳循环中的作用及其调节气候变化潜力的关键区域。除了是大气碳大量流入和深水形成的地区之外，南极环极水域主要营养物质的持续高浓度是海洋中尚未实现的初级生产潜力的最大资源库。该项目是一项更大努力的一部分，目的是验证铁的可用性限制了南大洋浮游植物的生产和生物量积累、营养物质的利用和二氧化碳的减少。Drs。Landry， Chisholm和Bidigare将通过研究铁富集和硅酸盐有效性对浮游植物群落的物种组成和大小结构以及浮游植物分类群特异性生长速率和荧光响应的影响做出贡献。从细菌到中浮游动物的浮游生物群落的功能和分类成分将通过流式细胞术、分类群特异性色素、视频图像分析显微镜和光学浮游生物计数的组合进行量化。此外，他们将使用稀释和肠道荧光技术来确定微型和中浮游动物对放牧的贡献，并评估放牧作为防止部分或全部浮游植物种群显著净增长的替代控制机制。该研究将从群落的角度来解释这些原位施肥试验，这对了解生物和地球化学反应的机制至关重要。

The Southern Ocean is a critical region for understanding the role of the oceans in global carbon cycling and its potential to regulate climate change. Besides being an area of high influx of atmospheric carbon and deep water formation, the persistently high concentrations of major nutrients in Antarctic circumpolar waters represent the largest pool of unrealized primary production potential in the oceans. This project is part of a larger effort to test the hypothesis that iron availability limits phytoplankton production and biomass accumulation, nutrient utilization and C02drawdown in the Southern Ocean. Drs. Landry, Chisholm and Bidigare, will contribute by investigating the effects of iron enrichment and silicate availability on the species composition and size structure of the plankton community and taxon-specific growth rates and fluorescence responses of the phytoplankton. Functional and taxonomic components of the plankton community from bacteria to mesozooplankton will be quantified by a combination of flow cytometry, taxon-specific pigments, video image-analysis microscopy and optical plankton counting. In addition, they will use dilution and gut fluorescence techniques to determine micro- and mesozooplankton contributions to grazing and to evaluate grazing as an alternate control mechanism preventing significant net growth of some or all of the phytoplankton populations. The research will bring a community perspective to the interpretation of these in situ fertilization experiments which is essential for a mechanistic understanding of the biological and geochemical responses.