Seasonal plankton dynamics in Kongsfjorden during two years of contrasting environmental conditions

Assmy, Philipp; Kvernvik, Ane C; Hop, Haakon; Hoppe, Clara Jule Marie; Chierici, Melissa; David, T. Divya; Duarte, Pedro; Fransson, Agneta; García, Laura M.; Patuła, Weronika; Kwaśniewski, Sławomir; Maturilli, Marion; Pavlova, Olga; Tatarek, Agnieszka; Wiktor, Józef; Wold, Anette; Wolf, Klara; Bailey, Allison

doi:10.1016/j.pocean.2023.102996

Cited by 21 publications

(10 citation statements)

References 145 publications

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“…), meroplankton (e.g., Bivalvia, Echinodermata, and Polychaeta), other zooplankton (e.g., Fritillaria borealis, Limacina helicina, Parasagitta elegans). The dry mass conversion factors from Hop et al (2019) with subsequent updates (Assmy et al, 2023) were applied for calculating zooplankton biomass.…”

Section: Zooplanktonmentioning

confidence: 99%

“…The abundance and biomass of the zooplankton in the glacial bays may also be a consequence of the glacial run-off, which contributes nutrients to the inner glacial bays (Halbach et al, 2019). The seasonal run-off from glaciers, with associated nutrients, are expected to fuel the summer blooms of mixed communities, involving diatoms, the prymnesiophyte Phaeocystis pouchetii and particularly smaller flagellates (Piwosz et al, 2009;Calleja et al, 2017;Halbach et al, 2019;Assmy et al, 2023). Some studies have documented massive blooms near the glacier front, in the inner basin, prior to the main run-off season in spring (Calleja et al, 2017), whereas others have documented later blooms in the middle or outer fjord (Hegseth and Tverberg, 2013).…”

Section: Figurementioning

confidence: 99%

“…These water masses mix on the shelf and are advected into the fjord as AW (T>3.0 °C, S>34.65) and Transformed Atlantic Water (TAW: T 1.0-3.0 °C , S >34.65; Svendsen et al, 2002). During the summer, AW and TAW typically dominate the hydrography of Kongsfjorden (Hop et al, 2006;Assmy et al, 2023;Santos-Garcıá et al, 2023), which is the main reason for referring to it as sub-Arctic when compared to the Arctic fjords in northern Svalbard (Hop et al, 2002;Santos-Garcıá et al, 2023).…”

Section: Introductionmentioning

confidence: 99%

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Tidewater glaciers as “climate refugia” for zooplankton-dependent food web in Kongsfjorden, Svalbard

et al. 2023

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With climate warming, many tidewater glaciers are retreating. Fresh, sediment-rich sub-glacial meltwater is discharged at the glacier grounding line, where it mixes with deep marine water resulting in an upwelling of a plume visible in front of the glacial wall. Zooplankton may suffer increased mortality within the plume due to osmotic shock when brought in contact with the rising meltwater. The constant replenishment of zooplankton and juvenile fish to the surface areas attracts surface-foraging seabirds. Because access to other feeding areas, such as the marginal ice zone, has become energetically costly due to reduced sea-ice extent, glacial plumes may become increasingly important as “climate refugia” providing enhanced prey availability. Here, we investigated zooplankton concentrations within the plume and adjacent waters of four tidewater glaciers in Kongsfjorden, Svalbard, in early August 2016 and late July 2017. Our aim was to compare the zooplankton composition, abundance, and isotopic signatures within the plumes to those in adjacent fjord and shelf waters. Our hypothesis was that the plumes resulted in increased zooplankton mortality through osmotic shock and increased prey availability to predators. The mortality due to osmotic shock in the glacial plume was low (<5% dead organisms in samples), although slightly higher than in surrounding waters. This indicates that plumes are inefficient “death traps” for zooplankton. However, the high abundance and biomass of zooplankton within plume areas suggest that the “elevator effect” of rising glacial water supplies zooplankton to the sea surface, thereby enhancing prey availability for surface-feeding seabirds. Thus, our study provides evidence that glacial plumes are important as “climate refugia” for foraging seabirds. Stable isotope signatures showed that the glacial bay zooplankton and fish community represent a distinct isotopic niche. Additionally, zooplankton mortality associated with the plume estimated over 100-days of melt season supports a flux of 12.8 tonnes of organic carbon to benthic communities in the glacial bays. Benthic scavengers, such as Onisimus caricus and Anonyx nugax, were abundant in the glacial bay, where they feed on sinking organic matter.

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Section: Zooplanktonmentioning

confidence: 99%

Section: Figurementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Tidewater glaciers as “climate refugia” for zooplankton-dependent food web in Kongsfjorden, Svalbard

et al. 2023

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“…Tidewater glaciers are important foraging areas for seabirds and marine mammals since the discharge of buoyant subglacial water induces a circulation that brings zooplankton to the surface, making them easy prey for surface-feeding predators (Stott, 1936;Lydersen et al, 2014;Bertrand et al, 2021, Hop et al 2023. The same mechanism can also influence fjord biogeochemistry and primary production through the entrainment of nutrient-rich bottom waters (e.g., Lydersen et al, 2014;Meire et al, 2017;Halbach et al, 2019;Hopwood et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

“…Most current studies focusing on the impact of tidewater glaciers on fjord biogeochemistry are either based on long-term monitoring at fixed locations, often distal to glacier calving fronts (Juul-Pedersen et al 2015;Assmy et al 2023) or are limited to short periods during the melt season (Meire et al 2017;Halbach et al 2019). Thus, most studies do not capture ephemeral but manuscript submitted to JGR Biogeosciences potentially critical glacier discharge events and their impact on fjord hydrology and biogeochemistry (Hopwood et al, 2020).…”

Section: Introductionmentioning

confidence: 99%

The impact of subglacial drainage system evolution and glacier lake outburst on Arctic fjord macronutrient dynamics: Kongsfjorden, Svalbard

Alexander,

Piermattei,

Assmy

et al. 2023

Preprint

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Rapid warming in the Arctic leads to increased glacier melt and freshwater runoff, especially from tidewater glaciers. Here, runoff enters the fjord at depth; induces upwelling and enhances macronutrient delivery to the fjords. However, most studies have low temporal resolutions and so the effects of low-frequency, high-amplitude events on the marine environment remain poorly known. Here, we combine glacier observations with fjord and glacier lake sampling to describe the impact of the 2021 glacier lake outburst flood (GLOF) from lake Setevatnet into Kongsfjorden (Svalbard). We demonstrate the importance of changing subglacial conditions and examine their effects upon macronutrient availability in the inner fjord. Our observations reveal that direct nutrient subsidy from the glacier is most important in early summer, providing critical nitrate (NO3-) and silicate following the routing of meltwater through an inefficient drainage system. Increasing quantities of ice melt force the establishment of an efficient drainage system, creating a plume in the inner fjord, and resulting in upwelling of nutrient-rich bottom water. When the sudden drainage of a glacier lake with high NO3- concentrations occurred, it left little imprint on the NO3- content of the inner fjord, and instead induced seasonal maximum nitrite (NO2-) concentrations. This outcome implies that NO3- was removed by denitrification at the glacier bed and its product NO2- was discharged by the flood waters into the inner fjord. Our findings show that the delivery of key, productivity-limiting nutrients from tidewater glaciers not only depends on runoff, but also on characteristics of the glacier drainage system.

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Productivity of Spitsbergen fjords ecosystems in summer—Spatial changes of in situ primary production in Kongsfjorden and Hornsund in the period 1994–2019

Dragańska‐Deja,

Stoń‐Egiert,

Wiktor

et al. 2024

Ecology and Evolution

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This comprehensive study examines primary production (PP) within the Spitsbergen fjords, Hornsund, and Kongsfjord, over a 25‐year period (1994–2019), across 45 stations and 348 incubation levels at various depths. PP and hydrological parameters were measured at 28 sampling stations in Kongsfjorden and 17 in Hornsund, with the locations of “Glacier,” “Inner,” and “Outer” zones defined to reflect the varying influence of glacial meltwater. Our study revealed spatial and temporal variability in PP, both at the surface and within the water column with very high depth resolution. The highest PP values were observed in the Glacier and Inner zones of Hornsund, particularly in the water layer up to 3 m depth, exceeding 20 mgC m−3 h−1. A notable decline in PP with increasing depth was observed in both fjords, with the Glacier zones displaying the highest productivity at the surface. The study also highlights the influence of glacial meltwater on surface water conditions, affecting the PP in the upper layers of both fjords. The observed gradient in the depth of maximum PP toward the mouth of the fjord varied between the two fjords, with Kongsjord displaying more dynamic variations. The spatial distribution of integrated primary production (Pi) suggested lower productivity in the glacial regions, likely due to light limitation caused by high concentrations of mineral particulate matter. The values of Pi were considerably higher in Hornsund, approximately twice as high overall, with specific emphasis on the Glacier and Inner zones where Pi values were about 6.5 and 2.5 times higher, respectively, when compared to those observed in Kongsfjord.

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Seasonal plankton dynamics in Kongsfjorden during two years of contrasting environmental conditions

Cited by 21 publications

References 145 publications

Tidewater glaciers as “climate refugia” for zooplankton-dependent food web in Kongsfjorden, Svalbard

Tidewater glaciers as “climate refugia” for zooplankton-dependent food web in Kongsfjorden, Svalbard

The impact of subglacial drainage system evolution and glacier lake outburst on Arctic fjord macronutrient dynamics: Kongsfjorden, Svalbard

Productivity of Spitsbergen fjords ecosystems in summer—Spatial changes of in situ primary production in Kongsfjorden and Hornsund in the period 1994–2019

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