Variability of size-fractionated chlorophyll a in the high-latitude Arctic Ocean in summer 2020  

作　　者：CAI Ting HAO Qiang BAI Youcheng LAN Musheng HE Jianfeng CHEN Jianfang 

机构地区：[1]Key Laboratory of Marine Ecosystem Dynamics,Ministry of Natural Resources,Hangzhou 310012,China [2]Second Institute of Oceanography,Ministry of Natural Resources,Hangzhou 310012,China [3]Key Laboratory of Polar Science,MNR,Polar Research Institute of China,Shanghai 200136,China

出　　处：《Advances in Polar Science》2022年第3期253-266,共14页极地科学进展（英文版）

基　　金：supported by the National Key R&D Program of China (Grant no. 2019YFE0120900);the National Natural Science Foundation of China (Grant nos. 41941013, 41976230, 41206181, and 41976229)

摘　　要：The size structure of phytoplankton has considerable effects on the energy flow and nutrient cycling in themarine ecosystem,and thus is important to marine food web and biological pump.However,its dynamics in the high-latitude Arctic Ocean,particularly ice-covered areas,remain poorly understood.We investigated size-fractionated chlorophyll a(Chl a)and related environmental parameters in the highly ice-covered Arctic Ocean during the summer of 2020,and analyzed the relationship between Chl adistribution and water mass through cluster analysis.Results showed that inorganic nutrients were typically depleted in the upper layer of the Canada Basin region,and that phytoplankton biomass was extremely low(mean=0.05±0.18 mg·m^(−3))in the near-surface layer(upper 25 m).More than 80%of Chl a values were<0.1 mg·m^(−3) in the water column(0-200 m),but high values appeared at the ice edge or in corresponding ice areas on the shelf.Additionally,the mean contribution of both nanoplankton(2-20μm)(41%)and picoplankton(<2μm)(40%)was significantly higher than that of microplankton(20-200μm)(19%).Notably,the typical subsurface chlorophyll maximum(0.1 mg·m^(−3))was found north of 80°N,where the concentration of sea ice reached approximately 100%.The Chl aprofile results showed that the deep chlorophyll maximum of total-,micro-,nano-,and picoplankton was located at depth of 40,39,41,and 38 m,respectively,indicating that nutrients are the primary factor limiting phytoplankton growth in the ice-covered Arctic Ocean during summer.These phenomena suggest that,despite the previous literatures pointing to significant light limitation under the Arctic ice,the primary limiting factor for phytoplankton in summer is still nutrient.

关 键 词：PHYTOPLANKTON size-fractionated chlorophyll a sea ice Arctic Ocean 

分 类 号：P731.15[天文地球—海洋科学]