Seasonal succession of net primary productivity, particulate organic carbon export, and autotrophic community composition in the eastern Bering Sea

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• 作者：S.B. Moran^a ; ^{moran@gso.uri.edu} ; M.W. Lomas^b ; R.P. Kelly^a ; R. Gradinger^c ; K. Iken^c ; J.T. Mathis^c
• 关键词：Bering Sea ; Primary productivity ; Phytoplankton ; Carbon ; Particles ; Thorium
• 刊名：Deep Sea Research Part II ; Topical Studies in Oceanography
• 出版年：2012
• 期刊代码：20_09670645
• 类别：ear
• 出版时间：15 June, 2012
• 卷：65-70
• 期：Complete
• 页码：84-97
• 文件大小：1581 K

摘要

Seasonal patterns in the partitioning of phytoplankton carbon during receding sea ice conditions in the eastern Bering Sea water column are presented using rates of ¹⁴C net primary productivity (NPP), phototrophic plankton carbon content, and POC export fluxes from shelf and slope waters in the spring (March 30-May 6) and summer (July 3-30) of 2008. At ice-covered and marginal ice zone (MIZ) stations on the inner and middle shelf in spring, NPP averaged 76卤93 mmol C m^鈭? d^鈭?, and in ice-free waters on the outer shelf NPP averaged 102卤137 mmol C m^鈭? d^鈭?. In summer, rates of NPP were more uniform across the entire shelf and averaged 43卤23 mmol C m^鈭? d^鈭? over the entire shelf. A concomitant shift was observed in the phototrophic pico-, nano-, and microplankton community in the chlorophyll maximum, from a diatom dominated system (80卤12%autotrophic C) in ice covered and MIZ waters in spring, to a microflagellate dominated system (71卤31%autotrophic C) in summer. Sediment trap POC fluxes near the 1%PAR depth in ice-free slope waters increased by 70%from spring to summer, from 10卤7 mmol C m^鈭? d^鈭? to 17卤5 mmol C m^鈭? d^鈭?, respectively. Over the shelf, under-ice trap fluxes at 20 m were higher, averaging 43卤17 mmol C m^鈭? d^鈭?. POC export over the shelf and slope estimated from ²³⁴Th deficits averaged 11卤5 mmol C m^鈭? d^鈭? in spring and 10卤2 mmol C m^鈭? d^鈭? in summer. Average e-ratios calculated on a station-by-station basis decreased by 鈭?0%from spring to summer, from 0.46卤0.48 in ice-covered and MIZ waters, to 0.33卤0.26 in summer, though the high uncertainty prevents a statistical differentiation of these data.