Seasonality of vertical flux and sinking particle characteristics in an ice-free high arctic fjord—Different from subarctic fjords?

Wiedmann, Ingrid; Reigstad, Marit; Marquardt, Miriam; Vader, Anna; Gabrielsen, Tove M.

doi:10.1016/j.jmarsys.2015.10.003

Cited by 38 publications

(40 citation statements)

References 66 publications

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“…During the second Atlantic advection event in April-May a salinity and temperature gradient was observed in the fjord, expanding from central to inner Kongsfjorden over time. Similar patterns were reported for Adventfjorden in 2014 (Wiedmann et al, 2016). The density of the intruding Atlantic water was higher than that of the inner fjord, resulting in advection at depth.…”

Section: Discussionsupporting

confidence: 81%

Atlantic Advection Driven Changes in Glacial Meltwater: Effects on Phytoplankton Chlorophyll-a and Taxonomic Composition in Kongsfjorden, Spitsbergen

et al. 2016

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Phytoplankton biomass and composition was investigated in a high Arctic fjord (Kongsfjorden, 79 • N, 11 • 40 ′ E) using year round weekly pigment samples collected from October 2013 to December 2014. In addition, phytoplankton dynamics supplemented with physical and chemical characteristics of the 2014 spring bloom (April-June 2014) were assessed in two locations in Kongsfjorden. The goal was to elucidate effects of Atlantic advection on spatial phytoplankton chlorophyll-a (chl-a) and taxonomic composition. Chl-a declined during the polar night to a minimum of 0.01 mg m −3 , followed by a 1000-fold increase until May 28. Atlantic advection prevented sea ice formation and increased springtime melting of marine terminating glaciers. This coincided with spatial and temporal differences in abundances of flagellates (prasinophytes, haptophytes, cryptophytes, and chrysophytes) and diatoms in early spring. More flagellated phytoplankton were observed in the non-stratified central Kongsfjorden, whereas diatoms were more abundant in the stratified inner fjord. Contrasting conditions between locations were reduced when glacial melt water stratification expanded toward the mouth of the fjord, mediating a diatom dominated surface bloom at both locations. We suggest that glacial melt water governs spring bloom spatial timing and composition in the absence of sea ice driven stratification. The spring bloom exhausted surface nutrient concentrations by the end of May. The nutrient limited post bloom period (June-October) was characterized by reduced biomass and pigments of flagellated phytoplankton, consisting of prasinophytes, haptophytes, chrysophytes, and to a lesser extent cryptophytes and peridinin-containing dinoflagellates.

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Section: Discussionsupporting

confidence: 81%

Atlantic Advection Driven Changes in Glacial Meltwater: Effects on Phytoplankton Chlorophyll-a and Taxonomic Composition in Kongsfjorden, Spitsbergen

et al. 2016

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“…However, the consistent agreement of our findings regarding stainability, porosity, and composition to existing literature (as discussed in the “Assessment” section) strongly suggest minimal disturbance of aggregates during embedding and slicing. Good structural preservation during embedding is further supported by observations of natural aggregates collected with gel traps in previous studies (Ebersbach and Trull ; Laurenceau‐Cornec et al 2015; Wiedmann et al ). Although some disturbance during sectioning and staining cannot be ruled out we have provided recommendations on how potential disturbances can be minimized ( see “Assessment” for details).…”

Section: Discussionsupporting

confidence: 70%

Embedding and slicing of intact in situ collected marine snow

Flintrop

Rogge

Miksch

et al. 2018

Limnology & Ocean Methods

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The biological carbon pump is largely driven by the formation and sinking of marine snow. Because of their high organic matter content, marine snow aggregates are hotspots for microbial activity, and microbial organic matter degradation plays an important role in the attenuation of carbon fluxes to the deep sea. Our inability to examine and characterize microscale distributions of compounds making up the aggregate matrix, and of possible niches inside marine snow, has hindered our understanding of the basic processes governing marine carbon export and sequestration. To address this issue, we have adapted soft‐embedding and sectioning to study the spatial structure and components of marine aggregates at high resolution. Soft‐embedding enables rapid quantitative sampling of undisturbed marine aggregates from the water column and from sediment traps, followed by spatially resolved staining and characterization of substrates of the aggregate matrix and the microorganisms attached to it. Particular strengths of the method include in situ embedding in sediment traps and successful fluorescence in situ hybridization (FISH)‐probe labeling, supporting studies of microbial diversity and ecology. The high spatial resolution achieved by thin‐sectioning of soft‐embedded aggregates offers the possibility for improved understanding of the composition and structure of marine snow, which directly influence settling velocity, microbial colonization and diversity, degradation rates, and carbon content. Our method will help to elucidate the small‐scale processes underlying large‐scale carbon cycling in the marine environment, which is especially relevant in the context of rising anthropogenic CO2 emissions and global change.

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“…and are estimated to account for 11% of the global long-term marine OC burial although they 61 cover < 0.1% of the global ocean surface area (Smith et al, 2015). However, carbon burial 62 rates vary more than ten fold among fjords, reflecting the diversity in productivity and key drivers governing the preservation efficiency, such as the OC amount of terrestrial origin, or entrained from the marine environment outside the fjord (Sørensen et al, 2015;Wiedmann et al, 2015). The boundaries for OC production and consumption in the fjords also play a crucial role in preservation efficiency (Burdige, 2007).…”

Section: Introduction 59mentioning

confidence: 99%

“…In distinct unpopulated areas climate change is the main cause for long-term changes (Rysgaard et al, 1998;Sørensen et al, 2015;Wiedmann et al, 2015), while eutrophication can alter the carbon cycle significantly in fjords near densely populated and industrial areas (Lomstein et al, 1998;Therkildsen et al, 1993). Faroese fjords may be subjected to both influences.…”

Section: Introduction 59mentioning

confidence: 99%

Deposition and benthic mineralization of organic carbon: A seasonal study from Faroe Islands

Norði

Glud

Simonsen

et al. 2018

Journal of Marine Systems

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Seasonal variations in sedimentation and benthic mineralization of organic carbon (OC) were investigated in a Faroese fjord. Deposited particulate organic carbon (POC) was mainly of marine origin, with terrestrial material only accounting for < 1%. On an annual basis the POC export from the euphotic zone amounted to 10.2 mol C m-2 yr-1 equating to 37% of the net primary production, and maximum sedimentation rates were associated to the spring bloom. The dynamics in the benthic solute exchange were governed by stratification that isolated the bottom water during summer and intensified sediment resuspension during winter. The POC export from the euphotic zone could not sustain the benthic mineralization rate (10.8 mol C 38 m-2 yr-1) and the calculated burial rate (9.8 mol C m-2 yr-1) of organic material in the central basin. This indicated considerable focusing of material in the central part of the fjord. This was supported by the fact that the measured benthic mineralization rate-in contrast to most investigations-actually increased with increasing water depth. In August, when mineralization was at its maximum, the dissolved inorganic carbon (DIC) release from the sediment increased by 2.2 mmol m-2 d-1 for every m increase in water depth at 30-60 m depth. Due to sediment focusing, the OC burial in the deepest part of the fjord was 9.8 mol C m-2 yr-1. This was 2.4 times higher than the average OC burial in the fjord, estimated from the total sedimentation, and benthic mineralization accounting for the water depth related changes in activity. The study in Kaldbaksfjøðrur underscore that fjords are important sites for long time OC burial, but emphasize the need for accounting for spatial variations when extrapolating results from a single or few stations to the scale of the entire fjord. 50

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Seasonality of vertical flux and sinking particle characteristics in an ice-free high arctic fjord—Different from subarctic fjords?

Cited by 38 publications

References 66 publications

Atlantic Advection Driven Changes in Glacial Meltwater: Effects on Phytoplankton Chlorophyll-a and Taxonomic Composition in Kongsfjorden, Spitsbergen

Atlantic Advection Driven Changes in Glacial Meltwater: Effects on Phytoplankton Chlorophyll-a and Taxonomic Composition in Kongsfjorden, Spitsbergen

Embedding and slicing of intact in situ collected marine snow

Deposition and benthic mineralization of organic carbon: A seasonal study from Faroe Islands

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