Spatial and vertical variability of primary production in the Kara Sea in July and August 2016: the influence of the river plume and subsurface chlorophyll maxima

Демидов, А. Б.; Гагарин, В. И.; Vorobieva, O. V.; Makkaveev, P. N.; Artemiev, V. A.; Khrapko, A. N.; Grigoriev, A. V.; Sheberstov, S. V.

doi:10.1007/s00300-017-2217-x

Cited by 29 publications

(8 citation statements)

References 66 publications

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“…Outside of the Laptev and Kara Sea ROFIs, the depth of the euphotic zone exceeds 20 m (Sorokin and Sorokin, 1996;Demidov et al, 2014), reaching the depth of the nutricline at ∼20-30 m (Pivovarov et al, 2005). In these more transparent waters with sufficient light below the SML, a subsurface chlorophyll maximum (SCM) can develop during the summer, when the nutrients in the SML are depleted (Demidov et al, 2018). This phenomenon has already been described in other marginal seas of the Arctic Ocean that are strongly influenced by riverine input, such as the Beaufort Sea (Carmack et al, 2004).…”

Section: Discussionmentioning

confidence: 88%

On the Variability of Stratification in the Freshwater-Influenced Laptev Sea Region

et al. 2020

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In this paper, we investigate the seasonal and spatial variability of stratification on the Siberian shelves with a case study from the Laptev Sea based on shipboard hydrographic measurements, year-round oceanographic mooring records from 2013 to 2014 and chemical tracer-based water mass analyses. In summer 2013, weak onshore-directed winds caused spreading of riverine waters throughout much of the eastern and central shelf. In contrast, strong southerly winds in summer 2014 diverted much of the freshwater to the northeast, which resulted in 50% less river water and significantly weaker stratification on the central shelf compared with the previous year. Our year-long records additionally emphasize the regional differences in water column structure and stratification, where the northwest location was well-mixed for 6 months and the central and northeast locations remained stratified into spring due to the lower initial surface salinities of the river-influenced water. A 26 year record of ocean reanalysis highlights the region’s interannual variability of stratification and its dependence on winds and sea ice. Prior the mid-2000s, river runoff to the perennially ice-covered central Laptev Sea shelf experienced little surface forcing and river water was maintained on the shelf. The transition toward less summer sea ice after the mid-2000s increased the ROFI’s (region of freshwater influence) exposure to summer winds. This greatly enhanced the variability in mixed layer depth, resulting in several years with well-mixed water columns as opposed to the often year-round shallow mixed layers before. The extent of the Lena River plume is critical for the region since it modulates nutrient fluxes and primary production, and further controls intermediate heat storage induced by lateral density gradients, which has implications for autumnal freeze-up and the eastern Arctic sea ice volume.MAIN POINTS1.CTD surveys and moorings highlight the regional and temporal variations in water column stratification on the Laptev Sea shelf.2.Summer winds increasingly control the extent of the region of freshwater influence under decreasing sea ice.3.Further reductions in sea ice increases surface warming, heat storage, and the interannual variability in mixed layer depth.

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Section: Discussionmentioning

confidence: 88%

On the Variability of Stratification in the Freshwater-Influenced Laptev Sea Region

et al. 2020

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“…In September 2007 and 2011, this atmospheric circulation pattern changed to southerly and south-westerly winds, while their average speed remained moderate. Monthly averaged wind speed was 2-3 m/s inAugust and September 2007, September 2011, July 2014, and July 2016. In July 2007, July and August 2011 August 2014, the average wind speed was 4-5 m/s.…”

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confidence: 97%

Structure of the Freshened Surface Layer in the Kara Sea During Ice‐Free Periods

et al. 2021

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The Kara Sea is a semi-enclosed sea located between the Siberian coast in the south, Novaya Zemlya in the west, and Severnaya Zemlya in the east (Figure 1). The water depth is less than 50 m at more than 40% of the Kara Sea; shallow areas are located mainly in the central and southeastern parts of the sea. This sea receives enormous freshwater discharge (∼1,500 km 3 annually) mainly from two large estuaries, namely, the Yenisei Gulf (630 km 3 from the Yenisei River) and the Gulf of Ob (530 km 3 from the Ob, Pur, and Taz rivers; Gordeev et al., 1996; Pavlov et al., 1996). Continental discharge to the Kara Sea has very large seasonal variability with a short freshet period in June-July that provides ∼50% of annual runoff and a long low discharge period in October-April caused by freezing of the inflowing rivers (Pavlov et al., 1996; Figure 1). Freshwater discharge forms the large freshened surface layer (FSL) in the Kara Sea which is among the largest freshwater reservoirs in the Arctic Ocean

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“…The SCM was observed in areas with a stratified water column and nitrate-poor surface waters at the northernmost shelf station and above the continental slope. The SCM occurred in some ice-free Arctic waters during late summer and early fall ( Martin et al., 2010 ; Arrigo et al., 2011 ; Ardyna et al., 2013 ; Brown et al., 2015 ; Demidov et al., 2018 ; Sukhanova et al., 2018 ). The SCM is located within the nutricline close to the lower boundary of the euphotic zone.…”

Section: Discussionmentioning

confidence: 99%

Picophytoplankton distribution along Khatanga Bay-shelf-continental slope environment gradients in the western Laptev Sea

Белевич

Демидов

Makkaveev

et al. 2021

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The spatial variations of photosynthetic picoplankton abundance and biomass and the picoplankton's contribution to chlorophyll a concentration along the transect from Khatanga Bay to the continental slope in the western part of the Laptev Sea were studied in September 2017. Picoeukaryotes dominated in the picophytoplankton communities. Picophytoplankton in Khatanga Bay showed more variability than those over the Laptev shelf and continental slope: abundance and biomass were the highest in the southern part of the bay and markedly decreased with increasing salinity in its northern part. Picocyanobacteria were found over the shelf and slope at temperatures of +2.4 to -1.6°С and salinity from 22 to 34. Picophytoplankton contribution to total chlorophyll a on the shelf was higher than in Khatanga Bay. The study of picophytoplankton of Khatanga Bay and in the western Laptev Sea can serve as a baseline for future assessment of the Laptev Sea ecosystem response to interannual and climate changes.

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Spatial and vertical variability of primary production in the Kara Sea in July and August 2016: the influence of the river plume and subsurface chlorophyll maxima

Cited by 29 publications

References 66 publications

On the Variability of Stratification in the Freshwater-Influenced Laptev Sea Region

On the Variability of Stratification in the Freshwater-Influenced Laptev Sea Region

Structure of the Freshened Surface Layer in the Kara Sea During Ice‐Free Periods

Picophytoplankton distribution along Khatanga Bay-shelf-continental slope environment gradients in the western Laptev Sea

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