Subglacial discharges create fluctuating foraging hotspots for sea birds in tidewater glacier bays

Urbański, Jacek; Stempniewicz, Lech; Węsławski, Jan Marcin; Dragańska‐Deja, Katarzyna; Wochna, Agnieszka; Goc, M.; Iliszko, Lech

doi:10.1038/srep43999

Cited by 60 publications

(54 citation statements)

References 41 publications

(62 reference statements)

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“…However, long-term studies of coastline changes in Kongsfjorden are also needed to quantify and constrain models to measure the impact of the climate warming on the whole Kongsfjorden ecosystem. Changes of glacier dynamics may also affect planktic and nektic fauna in the water column, in addition to seabirds and marine mammals (e.g., Lydersen et al 2014 ;Urbanski et al 2017). Hence, the current climate changes and their impacts make it imperative to increase our knowledge of climate-ocean-glacier systems.…”

Section: Discussion and Concluding Remarksmentioning

confidence: 99%

The marine sedimentary environments of Kongsfjorden, Svalbard: an archive of polar environmental change

et al. 2019

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Kongsfjorden, a fjord in north-western Svalbard, is characterized by large environmental gradients driven by meltwater processes along the margins of tidewater glaciers and the inflow of relatively warm Atlantic Water, the main heat source for the European Arctic. These factors make Kongsfjorden a key area to investigate changes in the polar climate-ocean-glacier system and to examine the resulting effects on the marine environment. The aim of this paper is to synthesize knowledge about the marine sedimentary environment in Kongsfjorden since the last deglaciation. Fjords act as natural sedimentary traps, archiving information about past and present environmental conditions and changes. Geological studies of Kongsfjorden have demonstrated a good potential for reconstructing palaeoenvironments and establishing baselines values for the natural climate changes in the Arctic. Palaeoceanographic reconstructions reveal rising water temperatures similar to modern temperatures ca. 12 000 years ago. The extent of warm Atlantic Water entering the fjords influences processes at, and the stability of, the margins of the tidewater glaciers. Enhanced inflow may cause accelerated glacial melting that, in consequence, leads to an increase in the sediment flux from the glacial catchments into the fjord, as observed ca. 12 000 years ago and at present. However, responses of sediment flux to modern environmental changes remain poorly understood, hence long-term and monitoring studies are needed to quantify and model the effects of climate warming on the sedimentary environment of Kongsfjorden.

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Section: Discussion and Concluding Remarksmentioning

confidence: 99%

The marine sedimentary environments of Kongsfjorden, Svalbard: an archive of polar environmental change

et al. 2019

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“…Subglacial discharge is a key component of tidewater glacier systems: it influences glacier dynamics by affecting basal friction (Kamb et al, ; Meier et al, ; Podrasky et al, ), it erodes and redistributes subglacial sediment (Cowan & Powell, ; Motyka et al, ), and it generates an upwelling plume that entrains warm ocean water (Straneo & Cenedese, ), melts glacier termini (Carroll et al, ; Slater et al, ), and drives a fjord‐scale exchange flow (Carroll et al, ; Jackson & Straneo, ). As a result, fjord waters tend to be productive, nutrient‐rich environments for plankton, fish, and sea birds (Arendt et al, ; Arimitsu et al, ; Lydersen et al, ; Meire et al, ; Urbanski et al, ). Variations in subglacial discharge likely affect the viability of these communities by impacting turbidity and nutrient concentrations.…”

Section: Introductionmentioning

confidence: 99%

Effect of Topography on Subglacial Discharge and Submarine Melting During Tidewater Glacier Retreat

Amundson

Carroll

2018

JGR Earth Surface

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To first order, subglacial discharge depends on climate, which determines precipitation fluxes and glacier mass balance, and the rate of glacier volume change. For tidewater glaciers, large and rapid changes in glacier volume can occur independent of climate change due to strong glacier dynamic feedbacks. Using an idealized tidewater glacier model, we show that these feedbacks produce secular variations in subglacial discharge that are influenced by subglacial topography. Retreat along retrograde bed slopes (into deep water) results in rapid surface lowering and coincident increases in subglacial discharge. Consequently, submarine melting of glacier termini, which depends on subglacial discharge and ocean thermal forcing, also increases during retreat into deep water. Both subglacial discharge and submarine melting subsequently decrease as glacier termini retreat out of deep water and approach new steady state equilibria. In our simulations, subglacial discharge reached peaks that were 6–17% higher than preretreat values, with the highest values occurring during retreat from narrow sills, and submarine melting increased by 14% for unstratified fjords and 51% for highly stratified fjords. Our results therefore indicate that submarine melting acts in concert with iceberg calving to cause tidewater glacier termini to be unstable on retrograde beds. The full impact of submarine melting on tidewater glacier stability remains uncertain, however, due to poor understanding of the coupling between submarine melting and iceberg calving.

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“…Glaciers are present in the innermost fjord basins and the meltwater discharge is responsible for the strong summer density stratification and resulting estuarine circulation (Promińska et al 2017). The water exchange in these fjords might be very dynamic (Jakacki et al 2017) due to the tidal currents, wind-driven advection from the shelf (Goszczko et al 2018), and glacial outflow (Urbanski et al 2017). The following water masses were separated on the basis of CTD data (IOPAN, unpublished data) collected during our study in the fjords: Atlantic Waters (salinity above 35, temperature above 2.5 °C), Local Coastal Waters (salinity around 34-35, temperature between 2.5 and 0 °C), Winter Cooled Waters (salinity above 35, temperature below 0 °C), and Surface Coastal Waters (salinity below 34 and temperature above 0 °C).…”

Section: Study Areamentioning

confidence: 99%

Plankton or benthos: where krill belongs in Spitsbergen fjords? (Svalbard Archipelago, Arctic)

2019

Self Cite

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This study couples observations of krill (Thysanoessa inermis, Thysanoessa longicaudata, Thysanoessa rashii) from Tucker trawl nets and cameras, trying to test hypothesis that in the glaciated fjords of Svalbard most of the euphausiids biomass is located in near-bottom habitat and explains why in this region there are a substantial part of the krill population near the sea floor. Photographic material from the summers of 2013-2017 shows large numbers of near-bottom euphausiids (39% of the total krill biomass in Hornsund and 41% in Kongsfjorden), which reached a maximum density of 751 ± 224 indiv. m −3 in Kongsfjorden, 731 ± 198 indiv. m −3 in Hornsund, and 426 ± 124 indiv. m −3 in Adventfjorden. Regional distribution of near-bottom aggregations of krill seem to be associated with close proximity to the glacier front rather than with depth. The highest densities were located in the glacial bays. Where and why these aggregations occur is probably complicated and dependent on many environmental factors acting together. However, the dominant factors seem to be sedimentation and estuarine circulation. No krill aggregations were found during the winter cruise. The dominating species was T. inermis which made up 90% of the community. Other krill species-T. rashii and T. longicaudata, made up 6% and 4%, respectively. In the summer, aggregations of other macrozooplankton were also observed: amphipods of the genus Themisto and chaetognaths of the genera Eukrohnia and Parasagitta. Euphausiid densities in the water column (from Tucker trawl hauls) were an order of magnitude lower (0.33 indiv. m −3 for Kongsfjorden and 0.61 indiv. m −3 for Hornsund) than those of the near-bottom aggregations observed on cameras system. At most stations, the krill exhibited a behaviour, known as "nose diving" in the sediment, which is likely related to feeding. Observation of this phenomenon may indicate that krill (mostly T. inermis), found near the bottom of Spitsbergen fjords, is looking for food there. Near-bottom aggregations of zooplankton, mainly krill, are common in glacial bays and can be important in the function of the fjord ecosystem. Our research proves that the zooplankton biomass can be highly underestimated if only Tucker trawl sampling is done, due to neglecting the near-bottom layer in this type of method.

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Subglacial discharges create fluctuating foraging hotspots for sea birds in tidewater glacier bays

Cited by 60 publications

References 41 publications

The marine sedimentary environments of Kongsfjorden, Svalbard: an archive of polar environmental change

The marine sedimentary environments of Kongsfjorden, Svalbard: an archive of polar environmental change

Effect of Topography on Subglacial Discharge and Submarine Melting During Tidewater Glacier Retreat

Plankton or benthos: where krill belongs in Spitsbergen fjords? (Svalbard Archipelago, Arctic)

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