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Annual cycle of export fluxes of biogenic matter near Hanna Shoal in the northeast Chukchi Sea
Deep Sea Research Part II: Topical Studies in Oceanography ( IF 2.3 ) Pub Date : 2020-01-07 , DOI: 10.1016/j.dsr2.2020.104730
Catherine Lalande , Jacqueline M. Grebmeier , Russell R. Hopcroft , Seth L. Danielson

The Chukchi Ecosystem Observatory (CEO), a mooring array of subsurface oceanographic instruments, was established on the northeast Chukchi Sea continental shelf to obtain time-series measurements of physical, biogeochemical, and biological parameters. A sequential sediment trap was deployed on a CEO mooring 8 m above seafloor to measure export fluxes of chlorophyll a (chl a), microalgal cells, zooplankton fecal pellets, total particulate matter (TPM), particulate organic carbon (POC), and zooplankton actively entering the trap from August 2015 to July 2016. These time-series measurements allowed us to monitor sympagic and pelagic algal production, the seasonal development of the zooplankton community, pelagic-benthic coupling, and particulate matter export in relation to snow and sea-ice cover on the shallow Chukchi Sea continental shelf. Notably, chl a and algal fluxes were nearly as high from August to October 2015 as in June–July 2016, indicating substantial autumn production. Autumn algal fluxes were dominated by the epipelic Cylindrotheca closterium while summer fluxes were dominated by pennate diatoms, including Fossula arctica and Neodenticula seminae. Peaks in the export of the exclusively sympagic diatom Nitzschia frigida in May and June 2016 indicated the release of ice algae due to snow and ice melt events. While pelagic copepods Calanus glacialis/marshallae, Pseudocalanus spp. and Oithona similis were the dominant copepods collected in the sediment trap, meroplanktonic stages of benthic organisms displayed the largest abundances and reflected mixing of pelagic stages and resuspension events on the shallow Chukchi Sea shelf. Enhanced fecal pellet carbon fluxes reflected zooplankton grazing in August and September 2015 and in July 2016. Despite the grazing pressure, high chl a, diatom and POC fluxes during these periods allowed strong pelagic-benthic coupling in the northeast Chukchi Sea. Persistent summer and autumn production also suggest that the local benthic community benefits from a sustained food supply rather than episodic flux events. Overall, these observations demonstrate the importance of year-round monitoring for fully understanding the phenology of marine processes and set a baseline for understanding the impact of environmental changes on Arctic marine ecosystems.



中文翻译:

楚科奇海东北部汉娜浅滩附近生物源物质出口通量的年循环

楚科奇生态系统天文台(CEO)是一系列地下海洋仪器的系泊设备,建立在东北的楚科奇海陆架上,以进行物理,生物地球化学和生物参数的时间序列测量。在海底以上8 m处的CEO处部署了一个连续的沉积物捕集阱,以测量叶绿素a(chl a),微藻细胞,浮游动物粪便颗粒,总颗粒物(TPM),有机碳颗粒(POC)和浮游动物从2015年8月至2016年7月活跃地进入陷阱。这些时间序列测量值使我们可以监测浮游藻类和浮游藻类的生产,浮游动物群落的季节性发展,浮游-底栖耦合以及与浅楚科奇海大陆架上的冰雪覆盖有关的颗粒物出口。值得注意的是,2015年8月至10月的chl a和藻类通量几乎与2016年6月至2016年7月的通量一样高,表明秋季的产量很高。秋季藻类通量主要由上流的Cylindrotheca closterium主导,而夏季藻类通量则由诸如Fossula arctica的戊状硅藻主导。和新齿na。2016年5月和2016年6月,仅具有共生能力的硅藻弗氏(Nitzschia frigida)的出口达到峰值,这表明由于雪和冰融化事件导致冰藻的释放。而上层co足类Calanus glacialis / MarshallaePseudocalanus spp。和长腹剑水蚤线虫是在沉淀物收集器收集的优势桡足类,底栖生物的浮游的阶段显示的最大的丰度和反映浮游阶段和再悬浮事件的浅楚科奇海货架上混合。增强的粪便颗粒碳通量反映浮游动物在八月和2015年9月和2016年七月放牧尽管放牧压力,高叶绿素在这些时期,硅藻和POC通量允许东北楚科奇海有强烈的上层-底栖耦合。持续的夏季和秋季生产还表明,当地的底栖生物群落受益于持续的粮食供应,而非突发性的通量事件。总体而言,这些观察结果证明了进行全年监测对于充分了解海洋过程物候的重要性,并为了解环境变化对北极海洋生态系统的影响奠定了基准。

更新日期:2020-01-07
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