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

Loma 0732359百慕大生物站研究公司提供资金来检验以下核心假设：气候驱动的海冰范围和持续时间的年际变化使东部白令海自养群落在两个状态之一之间转移；边缘冰带(MIZ)水华与开放水域水华。MIZ水华状态具有高生物量、硅藻为主的水华、高的远洋输出和紧密的浮游-底栖生物耦合的特征，而开阔水域水华的特征是生物量低、鞭毛状水华、低远洋输出和减少浮游-底栖耦合。该项目将使用传统的14C和13C方法产生初级生产量的测量，并使用创新的三重氧同位素技术和溶解氧浓度分别估计初级生产量的总和净。这种生产力测量的组合将被用来检验这样的假设，即虽然总初级生产力不会随着海冰面积的变化而变化，但净产量会随着海冰面积的变化而变化。浮游植物群落结构的测量将使PI能够检验他们的假设，即自养群落在密西西比河从硅藻为主的高出口系统转变为公开水域水华中以鞭毛虫为主的低出口系统。该项目是一个更大的项目的一部分，该项目旨在加深对东部白令海大陆架综合生态系统的了解，白令海大陆架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自足的猎人和渔民提供了重要的资源。描述浮游植物初级生产量的特征和浮游植物群落结构随海冰变化的变化，将提供有关食物链基础变化的信息，这些变化将制约生态系统的模型。这一信息将是该区域成功制定综合生态系统模型议定书的关键。

Lomas 0732359Bermuda Biological Station for Research, Inc. Funds 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.