Responses of the lower tropic level marine ecosystems to environmental variability in the Arctic Ocean.

I conducted this study based on the observational data taken during the research cruises by R/V Mirai for the Japan-Canada Joint Arctic Study （JWACS） in autumn of FY2002 and 2004。The purpose of this study is to understand influences of physical and chemical environmental variation on the structure of the lower trophic level ecosystems in the western Arctic Ocean。我主要关注两种copepod物种的生态学空间变化， Calanus hyperboreus和C. glacialis，以及该地区主要的二级生产商。2002财政年度的主要发现是区域特定的低拓扑结构和生产，我们用相应的物理生物特征定义了四个区域。沿海太平洋水域的流动和动力学的季节性海洋冰的恢复被认为是低地形水平观察到的区域变化的可能原因。就2004财政年度巡航的结果而言，我还发现了在Chukuchi Plateau （160-l70 ° W）之间的发展时间的空间变化：在东部和西部的复印机（160-l70 ° W）之间有较高的复印机可用性，在西部的缓慢而复印机开发和贫穷的植物箱在东部可以看到。冰边缘恢复的时间没有解释这一结果，但与表面层结构的东西方对比度相比，是由该区域的复杂水密集结构提出的，被认为是作为生态系统结构中空间差异的直接决定。《北极海冰的减少》已经报告了这些十年的情况，这些结果揭示了表面层结构中未来海冰的减少和相关的变化，可以从理论上改变西方北极海洋中的生态系统结构和生物生产。

I conducted this study based on the observational data taken during the research cruises by R/V Mirai for the Japan-Canada Joint Arctic Study (JWACS) in autumn of FY2002 and 2004. The purpose of this study is to understand influences of physical and chemical environmental variation on the structure of the lower trophic level ecosystems in the western Arctic Ocean. I particularly focus on the spatial variation of ecology of the two copepod species, Calanus hyperboreus and C.glacialis, which dominated secondary producers in this region. The major finding of the results of FY2002 cruise was region-specific lower-trophic level structure and production We defined the four regions with the respective physical-biological characteristics. Coastal Pacific water inflow and dynamics of seasonal sea ice retreat were considered as the possible causes of the observed regional variations of the lower trophic level. As for the results of the FY2004 cruises, I also found the spatial variation in developmental timing of copepods between the east and west of Chukuchi Plateau (160-l70゜W) : more advanced stage of the copepods with high diatom availability was observed in the west while slow copepod development and poor phytoplankton abundance were observed in the east. Timing of ice edge retreat did not explain this results, but east-west contrast of surface layer stratification, which was presented by the complex water mess structure of this region, was considered as the direct determinant of the spatial difference in the ecosystem structure. Reduction of the Arctic sea iice for these decades has been reported, and these results implicated the future sea ice reduction and associated changes in the surface layer structure could drastically alter the ecosystem structure and biological production in the western Arctic Ocean.