scholarly journals Large Diversity in Nitrogen- and Sulfur-Containing Compatible Solute Profiles in Polar and Temperate Diatoms

2020 ◽  
Vol 60 (6) ◽  
pp. 1401-1413
Author(s):  
H M Dawson ◽  
K R Heal ◽  
A Torstensson ◽  
L T Carlson ◽  
A E Ingalls ◽  
...  
Keyword(s):  
Organic Matter ◽  
Sea Ice ◽  
Algal Blooms ◽  
Dimethyl Sulfide ◽  
Compatible Solutes ◽  
Diatom Species ◽  
Variable Environment ◽  
Ice Melt ◽  
Isethionic Acid ◽  
Sulfur Containing

Synopsis Intense bottom-ice algal blooms, often dominated by diatoms, are an important source of food for grazers, organic matter for export during sea ice melt, and dissolved organic carbon. Sea-ice diatoms have a number of adaptations, including accumulation of compatible solutes, that allows them to inhabit this highly variable environment characterized by extremes in temperature, salinity, and light. In addition to protecting them from extreme conditions, these compounds present a labile, nutrient-rich source of organic matter, and include precursors to climate active compounds (e.g., dimethyl sulfide [DMS]), which are likely regulated with environmental change. Here, intracellular concentrations of 45 metabolites were quantified in three sea-ice diatom species and were compared to two temperate diatom species, with a focus on compatible solutes and free amino acid pools. There was a large diversity of metabolite concentrations between diatoms with no clear pattern identifiable for sea-ice species. Concentrations of some compatible solutes (isethionic acid, homarine) approached 1 M in the sea-ice diatoms, Fragilariopsis cylindrus and Navicula cf. perminuta, but not in the larger sea-ice diatom, Nitzschia lecointei or in the temperate diatom species. The differential use of compatible solutes in sea-ice diatoms suggests different adaptive strategies and highlights which small organic compounds may be important in polar biogeochemical cycles.

scholarly journals Evidence for significant protein-like dissolved organic matter accumulation in Sea of Okhotsk sea ice

2015 ◽  
Vol 56 (69) ◽  
pp. 1-8 ◽  
Author(s):  
Mats A. Granskog ◽  
Daiki Nomura ◽  
Susann Müller ◽  
Andreas Krell ◽  
Takenobu Toyota ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Sea Ice ◽  
Surface Waters ◽  
Sea Of Okhotsk ◽  
Sea Water ◽  
First Year ◽  
Ice Melt ◽  
Ultraviolet Range ◽  
Considerable Excess

AbstractAbsorption and fluorescence of chromophoric dissolved organic matter (CDOM) in sea ice and surface waters in the southern Sea of Okhotsk was examined. Sea-water CDOM had featureless absorption increasing exponentially with shorter wavelengths. Sea ice showed distinct absorption peaks in the ultraviolet, especially in younger ice. Older first-year sea ice had relatively flat absorption spectra in the ultraviolet range. Parallel factor analysis (PARAFAC) identified five fluorescent CDOM components, two humic-like and three protein-like. Sea water was largely governed by humic-like fluorescence. In sea ice, protein-like fluorescence was found in considerable excess relative to sea water. The accumulation of protein-like CDOM fluorescence in sea ice is likely a result of biological activity within the ice. Nevertheless, sea ice does not contribute excess CDOM during melt, but the material released will be of different composition than that present in the underlying waters. Thus, at least transiently, the CDOM introduced during sea-ice melt might provide a more labile source of fresher protein-like DOM to surface waters in the southern Sea of Okhotsk.

scholarly journals Characteristics of Chromophoric and Fluorescent Dissolved Organic Matter in the Nordic Seas

2018 ◽  
Author(s):  
Anna Makarewicz ◽  
Piotr Kowalczuk ◽  
Sławomir Sagan ◽  
Mats A. Granskog ◽  
Alexey K. Pavlov ◽  
...  
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Sea Ice ◽  
Chlorophyll A ◽  
Saline Water ◽  
Atlantic Water ◽  
Nordic Seas ◽  
Ice Melt ◽  
Fluorescent Dissolved Organic Matter ◽  
West Spitsbergen

Abstract. Optical properties of Chromophoric (CDOM) and Fluorescent Dissolved Organic Matter (FDOM) were characterized in the Nordic Seas including the West Spitsbergen Shelf during June–July of 2013, 2014 and 2015. The CDOM absorption coefficient at 350 nm, aCDOM(350) showed significant interannual variation. In 2013, the highest average aCDOM(350) values (aCDOM = 0.30 ± 0.12 m−1) were observed due to the influence of cold and low–saline water from the Sørkapp Current in the southern part of West Spitsbergen Shelf. In 2014, aCDOM(350) values were significantly lower than in 2013 (av. aCDOM(350) = 0.14 ± 0.06 m−1), which was associated with the dominance of warm and saline Atlantic Water (AW) in the region, while in 2015 intermediate CDOM absorption (av. aCDOM(350) = 0.19 ± 0.05 m−1) was observed. In situ measurement of three FDOM components revealed that protein–like FDOM dominated and concentration of marine and terrestrial humic–like DOM were very low and its distribution were generally vertically homogenous in the upper ocean (0–100 m). Fluorescence of terrestrial and marine humic–like FDOM decreased in surface waters (0–15 m) near the sea–ice edge by dilution of oceanic waters by sea–ice melt water. The vertical distribution of protein–like FDOM was characterized by a prominent sub–surface maximum that matched the subsurface chlorophyll a maximum and was observed all across the study area. The highest protein–like FDOM fluorescence was observed in the Norwegian Sea in the core of warm AW. There was a significant relationship between the protein–like fluorescence and chlorophyll a fluorescence (R2 = 0.65, p 

Unexpectedly high dimethyl sulfide concentration in high-latitude Arctic sea ice melt ponds

2019 ◽  
Vol 21 (10) ◽  
pp. 1642-1649 ◽  
Author(s):  
Keyhong Park ◽  
Intae Kim ◽  
Jung-Ok Choi ◽  
Youngju Lee ◽  
Jinyoung Jung ◽  
...  
Keyword(s):  
Sea Ice ◽  
High Latitude ◽  
Dimethyl Sulfide ◽  
Arctic Sea Ice ◽  
Sulfide Concentration ◽  
Sea Ice Concentration ◽  
Ice Melt ◽  
Melt Ponds ◽  
Arctic Sea ◽  
Ice Concentration

Dimethyl sulfide (DMS) production in the northern Arctic Ocean has been considered to be minimal because of high sea ice concentration and extremely low productivity.

scholarly journals Bacterial diversity and lipid biomarkers in sea ice and sinking particulate organic material during the melt season in the Canadian Arctic

Elem Sci Anth ◽  
2021 ◽  
Vol 9 (1) ◽  
Author(s):  
Rémi Amiraux ◽  
Jean-François Rontani ◽  
Fabrice Armougom ◽  
Eléonore Frouin ◽  
Marcel Babin ◽  
...  
Keyword(s):  
Organic Matter ◽  
Sea Ice ◽  
Organic Material ◽  
Early Stage ◽  
Canadian Arctic ◽  
Carbon Fluxes ◽  
Enzymatic Activities ◽  
Ice Melt ◽  
Sinking Particles ◽  
Potential Biomarkers

The estimation of important carbon fluxes in a changing Arctic environment remains a challenge, one that could benefit from the development of biomarkers that distinguish between sympagic (ice-associated) and pelagic organic material. Products of 10S-DOX-like lipoxygenase and fatty acid cis-trans isomerase (CTI) activity of bacteria attached to sympagic particulate organic matter (POM) were proposed previously as potential biomarkers of the contribution of sympagic biota to carbon fluxes to the seafloor. To date, neither the bacteria involved in such enzymatic activities nor the detection of these potential biomarkers at their presumed source (i.e., sea ice) has been investigated. Here, we determined and compared the diversity of prokaryotic communities (based on operational taxonomic units) attached to sea ice POM and under-ice sinking particles during an early stage of ice melt (brine drainage) in Baffin Bay (Canadian Arctic). Based on a time series of biodiversity analyses and the quantification of lipid tracers of these two bacterial enzymatic activities, we suggest that CTI-active bacteria, exposed to hypersaline stress, are attached to algal POM just above bottom sea ice and released into the water column following brine drainage. In contrast, bacteria attached to sinking particles and exhibiting 10S-DOX-like lipoxygenase activity are suggested to come from the bottommost layer of sea ice, where they may play a role in the detoxification of algae-produce free fatty acids. These results provide a refined view of the potential use of products of CTI activity as specific biomarkers of sympagic organic matter.

scholarly journals Dimethyl sulfide dynamics in first-year sea ice melt ponds in the Canadian Arctic Archipelago

2018 ◽  
Vol 15 (10) ◽  
pp. 3169-3188 ◽  
Author(s):  
Margaux Gourdal ◽  
Martine Lizotte ◽  
Guillaume Massé ◽  
Michel Gosselin ◽  
Michel Poulin ◽  
...  
Keyword(s):  
Sea Ice ◽  
Dimethyl Sulfide ◽  
De Novo ◽  
Canadian Arctic ◽  
The Arctic ◽  
First Year ◽  
Canadian Arctic Archipelago ◽  
Ice Melt ◽  
Melt Ponds ◽  
Arctic Atmosphere

Abstract. Melt pond formation is a seasonal pan-Arctic process. During the thawing season, melt ponds may cover up to 90 % of the Arctic first-year sea ice (FYI) and 15 to 25 % of the multi-year sea ice (MYI). These pools of water lying at the surface of the sea ice cover are habitats for microorganisms and represent a potential source of the biogenic gas dimethyl sulfide (DMS) for the atmosphere. Here we report on the concentrations and dynamics of DMS in nine melt ponds sampled in July 2014 in the Canadian Arctic Archipelago. DMS concentrations were under the detection limit (< 0.01 nmol L−1) in freshwater melt ponds and increased linearly with salinity (rs = 0.84, p ≤ 0.05) from ∼ 3 up to ∼ 6 nmol L−1 (avg. 3.7 ± 1.6 nmol L−1) in brackish melt ponds. This relationship suggests that the intrusion of seawater in melt ponds is a key physical mechanism responsible for the presence of DMS. Experiments were conducted with water from three melt ponds incubated for 24 h with and without the addition of two stable isotope-labelled precursors of DMS (dimethylsulfoniopropionate), (D6-DMSP) and dimethylsulfoxide (13C-DMSO). Results show that de novo biological production of DMS can take place within brackish melt ponds through bacterial DMSP uptake and cleavage. Our data suggest that FYI melt ponds could represent a reservoir of DMS available for potential flux to the atmosphere. The importance of this ice-related source of DMS for the Arctic atmosphere is expected to increase as a response to the thinning of sea ice and the areal and temporal expansion of melt ponds on Arctic FYI.

scholarly journals Impact of sea-ice melt on dimethyl sulfide (sulfoniopropionate) inventories in surface waters of Marguerite Bay, West Antarctic Peninsula

2018 ◽  
Vol 376 (2122) ◽  
pp. 20170169 ◽  
Author(s):  
Jacqueline Stefels ◽  
Maria A. van Leeuwe ◽  
Elizabeth M. Jones ◽  
Michael P. Meredith ◽  
Hugh J. Venables ◽  
...  
Keyword(s):  
Sea Ice ◽  
Antarctic Peninsula ◽  
Surface Waters ◽  
Dimethyl Sulfide ◽  
Organic Sulfur Compound ◽  
The West ◽  
Ice Melt ◽  
West Antarctic ◽  
Marguerite Bay ◽  
West Antarctic Peninsula

The Southern Ocean is a hotspot of the climate-relevant organic sulfur compound dimethyl sulfide (DMS). Spatial and temporal variability in DMS concentration is higher than in any other oceanic region, especially in the marginal ice zone. During a one-week expedition across the continental shelf of the West Antarctic Peninsula (WAP), from the shelf break into Marguerite Bay, in January 2015, spatial heterogeneity of DMS and its precursor dimethyl sulfoniopropionate (DMSP) was studied and linked with environmental conditions, including sea-ice melt events. Concentrations of sulfur compounds, particulate organic carbon (POC) and chlorophyll a in the surface waters varied by a factor of 5–6 over the entire transect. DMS and DMSP concentrations were an order of magnitude higher than currently inferred in climatologies for the WAP region. Particulate DMSP concentrations were correlated most strongly with POC and the abundance of haptophyte algae within the phytoplankton community, which, in turn, was linked with sea-ice melt. The strong sea-ice signal in the distribution of DMS(P) implies that DMS(P) production is likely to decrease with ongoing reductions in sea-ice cover along the WAP. This has implications for feedback processes on the region's climate system. This article is part of the theme issue ‘The marine system of the West Antarctic Peninsula: status and strategy for progress in a region of rapid change’.

Diversity and strength of ice-related dimethyl sulfide sources in the Arctic

2020 ◽  
Author(s):  
Maurice Levasseur ◽  
Martine Lizotte ◽  
Virginie Galindo ◽  
Margaux Gourdal ◽  
Michel Gosselin
Keyword(s):  
Sea Ice ◽  
Dimethyl Sulfide ◽  
Ultrafine Particle ◽  
The Arctic ◽  
Sea Ice Extent ◽  
Ice Melt ◽  
Melt Ponds ◽  
Marginal Ice Zone ◽  
Projected Changes ◽  
Ice Water

&lt;p&gt;Biogenic sources of sulfur are important precursors of aerosols in the Arctic during the summer months. Recent studies show that peaks in ultrafine particle formation events often coincide with hotspots of dimethyl sulfide (DMS) emissions from the marginal ice zone. During the last 10 years, we explored the diversity of DMS sources associated with the ice and at the marginal ice zone in the Canadian Arctic, and assessed how the projected changes in sea ice extent, thickness, and other properties could strengthen or weaken these emissions. Results from four Arctic expeditions presenting DMS concentrations and dynamics in snow, sea ice, melt ponds, under-ice water, and at the ice edge will be shown and discussed in the context of ongoing and future changes in the cryosphere. The analysis of the pooled dataset points toward an increase in DMS emissions in a warmer Arctic with a potential cooling feedback on climate.&lt;/p&gt;

An annual cycle of diatom succession in two contrasting Greenlandic fjords: from simple sea-ice indicators to varied seasonal strategists

2020 ◽  
Author(s):  
Tiia Luostarinen ◽  
Sofia Ribeiro ◽  
Kaarina Weckström ◽  
Mikael Sejr ◽  
Lorenz Meire ◽  
...  
Keyword(s):  
Sea Ice ◽  
Indicator Species ◽  
Cold Water ◽  
High Arctic ◽  
Sediment Traps ◽  
Diatom Species ◽  
Factors Affecting ◽  
Ice Melt ◽  
Species Succession ◽  
Fragilariopsis Cylindrus

&lt;p&gt;Understanding environmental factors affecting diatom species composition at seasonal resolution can contribute to the improvement of paleo sea-ice reconstruction. We recorded diatom species succession over one full year (May 2017&amp;#8210;May 2018) using automated sediment traps installed in two contrasting Greenlandic fjords: seasonally ice-covered Young Sound in high arctic NE Greenland and nearly sea-ice free Godth&amp;#229;bsfjord in subarctic SW Greenland. The two study sites had distinct seasonal regimes in terms of both sediment and diatom fluxes. In Young Sound, diatom fluxes peaked during the ice-melt in June&amp;#8211;July (max. 880&amp;#215;10&lt;sup&gt;6&lt;/sup&gt; valves m&lt;sup&gt;-2 &lt;/sup&gt;d&lt;sup&gt;-1&lt;/sup&gt;), but were very low (0.11&amp;#173;&amp;#8211;12.7&amp;#215;10&lt;sup&gt;6&lt;/sup&gt; valves m&lt;sup&gt;-2 &lt;/sup&gt;d&lt;sup&gt;-1&lt;/sup&gt;) for the rest of the year. The pattern was very different in Godth&amp;#229;bsfjord, where diatom fluxes were more stable throughout the year and at maximum 320&amp;#215;10&lt;sup&gt;6&lt;/sup&gt; valves m&lt;sup&gt;-2 &lt;/sup&gt;d&lt;sup&gt;-1&lt;/sup&gt; in summer. A total of 60 diatom taxa were present in Young Sound and 50 in Godth&amp;#229;bsfjord, with 19 and 22 sympagic or pelagic species, respectively. The diatom assemblage in Young Sound is strongly dominated by the pennate sea-ice species&lt;em&gt; Fragilariopsis oceanica&lt;/em&gt;, &lt;em&gt;Fragilariopsis reginae-jahniae&lt;/em&gt; and &lt;em&gt;Fossula arctica&lt;/em&gt;, which exhibited pulse-like deposition in the trap during and after the ice melt. In Godth&amp;#229;bsfjord, the fluxes were dominated by resting spores of centric Chaetoceros, while the rest of the assemblage was characterized by the cold-water indicator species &lt;em&gt;Detonula confervacea&lt;/em&gt; spore, &lt;em&gt;Fragilariopsis cylindrus&lt;/em&gt; and &lt;em&gt;Thalassiosira antarctica&lt;/em&gt; var. &lt;em&gt;borealis&lt;/em&gt; spore accompanied by some warmer-water species. Some sea-ice indicator species were also observed in Godth&amp;#229;bsfjord, but at very low counts and throughout the year, likely transported from the inner fjord, which experiences seasonal sea-ice coverage. We show that &lt;em&gt;F. oceanica&lt;/em&gt;, &lt;em&gt;F. reginae-jahniae&lt;/em&gt; and &lt;em&gt;F. arctica&lt;/em&gt; exhibit similar seasonal behaviour and are clearly linked to sea ice. On the other hand,&lt;em&gt; Fragilariopsis cylindrus&lt;/em&gt; seems to have a more flexible niche, and is not an unequivocal ice indicator. Similarly, &lt;em&gt;Pauliella taeniata&lt;/em&gt; has a differing niche, and does not favour our study locations probably due to its preference for lower salinities. We underscore the importance of taking into account ecological and seasonal preferences of the individual diatom species when reconstructing past sea-ice conditions qualitatively or quantitatively.&lt;/p&gt;

scholarly journals Inherent optical properties and optical characteristics of dissolved organic and particulate matter in an Arctic fjord (Storfjorden, Svalbard) in early summer

2021 ◽  
Author(s):  
Tristan Petit ◽  
Børge Hamre ◽  
Håkon Sandven ◽  
Rüdiger Röttgers ◽  
Piotr Kowalczuk ◽  
...  
Keyword(s):  
Organic Matter ◽  
Optical Properties ◽  
Dissolved Organic Matter ◽  
Sea Ice ◽  
Water Absorption ◽  
Light Attenuation ◽  
Early Summer ◽  
Ice Melt ◽  
Sea Bed ◽  
Ice Production

Abstract. There have been considerable efforts to understand the hydrography of the Storfjorden fjord (Svalbard). A recurring winter polynya with large sea ice production makes it an important region of dense water formation at the scale of the Arctic Ocean. In addition, this fjord is seasonally influenced by freshwater inputs from sea-ice melt and the surrounding islands of the Svalbard archipelago which impacts the hydrography. However, the understanding of factors controlling the optical properties of the waters in Storfjorden are lacking and are crucial for development of more accurate regional bio-optical models. Here, we present results from the first detailed optical field survey of Storfjorden conducted in early summer of 2020. In addition to the expected seasonal contribution from phytoplankton, we find that in early summer waters in Storfjorden are optically complex with a significant contribution from coloured dissolved organic matter (33–64 % of the non-water absorption at 443 nm) despite relatively low CDOM concentrations, and in the nearshore or near seabed from non-algal particles (up to 61 % of the non-water absorption at 550 nm). In surface waters, the spatial variability of light attenuation was mainly controlled by inorganic suspended matter originating from river runoff. A distinct subsurface maximum of light attenuation was largely driven by a subsurface phytoplankton bloom, controlled by stratification resulting from sea-ice melt. Lastly, the cold dense bottom waters of Storfjorden, from winter sea ice production, which periodically overflows into the Fram Strait, was found to contain elevated levels of both non-algal particles and dissolved organic matter, which is likely caused by the dense flows of the nepheloid layer interacting with the sea bed.

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