北冰洋浮游生物空间分布及其季节变化的模拟

低营养级浮游生物生态动力过程对环境变化的响应非常敏感。随着全球气候变化加剧，北冰洋正在经历快速的环境变化。厘清北冰洋低营养级浮游生物季节分布与变化特征是探究北冰洋生态系统对环境快速变化响应的前提，也是评估北极海区固碳能力的重要依据。基于此，本文构建了海洋–海冰–生物地球化学循环模型，并对北冰洋叶绿素浓度以及浮游生物结构的时空变化特征进行了模拟，结果表明:(1)北冰洋表层叶绿素浓度的峰值主要出现在5月，且太平洋一侧叶绿素浓度高于大西洋一侧；随着海水层化，表层受营养盐限制的海区呈现次表层叶绿素浓度最大值现象，且由陆架向海盆，次表层叶绿素浓度最大值层逐渐加深；9月，叶绿素浓度高值重回水体上层，太平洋一侧海区表层叶绿素浓度呈现较为明显的次峰值。(2)由于太平洋和大西洋入流营养盐浓度及结构的不同，北冰洋表层浮游生物群落结构存在明显空间差异。太平洋一侧，硅藻和中型浮游动物占优，硅藻在5月和9月出现生物量峰值，微型浮游植物在3月、5月和6月维持相对较高生物量；而大西洋一侧，在早春－春末夏初－夏秋经历了微型浮游植物－硅藻－微型浮游植物的演替，总体而言，微型浮游植物和微型浮游动物占优。此外，两侧海区浮游动物浓度峰值相较浮游植物滞后约半月。

Simulation of spatial distribution and seasonal variation of plankton in the Arctic Ocean

Eco-dynamics of marine plankton are remarkably sensitive to changes in their environments. The Arctic Ocean is undergoing rapid environmental changes as the global climate change intensifies. Understanding the seasonal distribution and variation of low-trophic plankton is a prerequisite for exploring the response of ecosystem to changing environment in the Arctic Ocean, and is also an important basis for assessing the carbon sequestration capacity of the Arctic Ocean. Based on above, a coupled ocean-sea ice-biogeochemical cycling model was developed and applied to evaluate the temporal-spatial variations of chlorophyll a concentration and planktonic structures in the Arctic Ocean. The results suggested that:(1) surface chlorophyll a concentration mainly peaks in May, with the higher values on the Pacific side than the Atlantic; since stratification occurs, subsurface chlorophyll a maximums are found in areas having limited nutrients at surface, and the depth of subsurface chlorophyll a maximums gradually deepens from the shelf towards the basin; in September, the high chlorophyll a concentration returns to the upper layer from the subsurface, presenting a sub-peak of surface chlorophyll a concentration on the Pacific side. (2) Substantial regional differences in surface plankton communities exist in the Arctic Ocean due to the influences of the Pacific and Atlantic inflows with variations in nutrients concentrations and structures. Diatom and mesozooplankton are dominant species on the Pacific side where diatom biomass exhibits two peaks in May and September, meanwhile nanophytoplankton maintains relatively high biomass in March, May and June. Atlantic side experiences a seasonal succession from nanophytoplankton to diatom then to nanophytoplankton corresponding to early spring, late spring-early summer, and summer-autumn, respectively. Over the entire growth season, nanophytoplankton and microzooplankton dominate on the Atlantic side. Generally, the peak biomass of zooplankton has a lag for half a month to the peak of phytoplankton biomass in the Arctic Ocean.