Collaborative Proposal - BEST: The Impact of Changes in Sea Ice Extent on Primary Production, Phytoplankton Community Structure, and Export in the eastern Bering Sea

莫兰0732680大学。提供的资金用于验证以下核心假设：气候驱动的海冰范围和持续时间的年际变化使白令海东部自养群落在两个州之一之间转移；边缘冰区（MIZ）水华与开放水域水华。MIZ水华状态的特征是高生物量、硅藻为主的华花、高远洋输出和紧密的远洋-底栖耦合，而开放水域水华状态的特征是低生物量、鞭毛虫华花、低远洋输出和减少的远洋-底栖耦合。该项目将使用传统的14C和13C方法测量初级产量，并使用创新的三氧同位素技术和溶解氧浓度分别估算总初级产量和净初级产量。这种生产力测量的组合将用于检验一个假设，即虽然总初级产量不随海冰范围而变化，但净产量却随海冰范围而变化，并且与海冰范围成反比。浮游植物群落结构测量将允许pi检验他们的假设，即自养群落从MIZ中以硅藻为主的高出口系统转变为开放水域中以鞭毛虫为主的低出口系统。该项目是一个更大项目的一部分，旨在了解白令海东部陆架的综合生态系统，这是美国沿海水域的一个高产地区。这个生态系统是美国大部分商业渔业的家园，也为阿拉斯加的自给猎人和渔民提供了重要的资源。浮游植物初级生产速率的特征和浮游植物群落结构的变化对海冰条件变化的响应将提供有关食物链底层变化的信息，这些变化将限制生态系统模型。这些信息对于该地区成功的综合生态系统建模协议至关重要。

Moran 0732680Univ. of Rhode IslandFunds are provided to test the following core hypothesis: climate-driven interannual variability in sea-ice extent and duration shifts the eastern Bering Sea autotrophic community between one of two states; marginal ice-zone (MIZ) blooms vs. open-water blooms. The MIZ bloom state is characterized by high biomass, diatom-dominated blooms, high pelagic export and tight pelagic-benthic coupling, whereas the open-water bloom state is characterized by lower biomass, flagellate blooms, low pelagic export, and reduced pelagic-benthic coupling. This project will generate measurements of primary production using traditional 14C, 13C methods, and use the innovative triple oxygen isotope technique and dissolved oxygen concentrations to estimate gross and net primary production, respectively. This combination of productivity measurements will be used to test the hypothesis that while gross primary production does not change with sea-ice extent, net production does, and is inversely related to sea-ice extent.Phytoplankton community structure measurements will allow the PIs to test their hypothesis that the autotrophic community switches from a diatom-dominated, high export system in the MIZ, to a flagellate-dominated, lower export, system in open water blooms. This project is part of a larger program designed to develop understanding of the integrated ecosystem of the eastern Bering Sea shelf, a highly productive region of US coastal waters. This ecosystem is home to a major portion of the commercial fisheries of the US and also provides significant resources to subsistence hunters and fisherman of Alaska. Characterization of rates of primary production by phytoplankton and the varying structure of the phytoplankton community in response to changing sea ice conditions will provide information about changes at the base of the food chain that will constrain models of the ecosystem. This information will be essential to a successful integrated ecosystem modeling protocol for the region.