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Schnack-Schiel, S.B.; Thomas, D.N.; Haas, C.; Dieckmann, G.S.; Alheit, R. |
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Title |
The occurrence of the copepods Stephos longipes (Calanoida) and Drescheriella glacialis (Harpacticoida) in summer sea ice in the Weddell Sea, Antarctica |
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Journal Article |
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Year |
2001 |
Publication |
Antarctic Science |
Abbreviated Journal |
Antarctic Sci |
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Volume |
13 |
Issue |
2 |
Pages  |
150-157 |
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Keywords |
copepods; Drescheriella glacialis; sea ice; seasonality; Stephos longipes |
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Abstract |
In January to March 1997, a RV Polarstern cruise that transected the Weddell Sea resulted in samples being taken in thick pack ice in the south-eastern Weddell Sea and then along the marginal ice edge towards the Antarctic Peninsula. Several ice types were thus sampled over a wide geographic area during late summer/early autumn. Common features of the first warm period was the occurrence of surface ponds, and that many floes had quasi-continuous horizontal gaps, underlying a layer of ice and metamorphic snow. With the onset of cold air temperatures in late February the gaps rapidly refroze. The calanoid copepod Stephos longipes occurred in all habitats encountered and showed highest numbers in the surface ice in summer, in the gap water during both seasons and in the refrozen gap water in autumn. Nauplii outnumbered copepodids in the surface ice and refrozen gap water, while in the gap water copepodids, mainly stages CI-CIII in summer and CII-CIV in autumn, comprised about 70% of the total population. The harpacticoid species Drescheriella glacialis did not occur in all habitats and was missing in surface ponds and new ice. Nauplii of D. glacialis were rarely found in gapwater, but predominated in the refrozen gaps. |
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0954-1020 |
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refbase @ admin @ Schnack-Schiel++2001_2 |
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753 |
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Granskog, M.; Kaartokallio, H.; Kuosa, H.; Thomas, D.N.; Vainio, J. |
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Title |
Sea ice in the Baltic Sea – A review |
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Journal Article |
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Year |
2006 |
Publication |
Estuarine, Coastal and Shelf Science |
Abbreviated Journal |
Estuar Coast Shelf Sci |
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70 |
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1-2 |
Pages |
145-160 |
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Keywords |
sea ice; Baltic Sea; biogeochemistry; plankton; seasons |
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Although the seasonal ice cover of the Baltic Sea has many similarities to its oceanic counterpart in Polar Seas and Oceans, there are many unique characteristics that mainly result from the brackish waters from which the ice is formed, resulting in low bulk salinities and porosities. In addition, due to the milder climate than Polar regions, the annual maximum ice extent is highly variable, and rain and freeze-melt cycles can occur throughout winter. Up to 35% of the sea ice mass can be composed from metamorphic snow, rather than frozen seawater, and in places snow and superimposed ice can make up to 50% of the total ice thickness. There is pronounced atmospheric deposition of inorganic nutrients and heavy metals onto the ice, and in the Bothnian Bay it is estimated that 5% of the total annual flux of nitrogen and phosphorus and 20–40% of lead and cadmium may be deposited onto the ice fields from the atmosphere. It is yet unclear whether or not the ice is simply a passive store for atmospherically deposited compounds, or if they are transformed through photochemical processes or biological accumulation before released at ice and snow melt.As in Polar sea ice, the Baltic ice can harbour rich biological assemblages, both within the ice itself, and on the peripheries of the ice at the ice/water interface. Much progress has been made in recent years to study the composition of these assemblages as well as measuring biogeochemical processes within the ice related to those in underlying waters. The high dissolved organic matter loading of Baltic waters and ice result in the ice having quite different chemical characteristics than those known from Polar Oceans. The high dissolved organic material load is also responsible in large degree to shape the optical properties of Baltic Sea ice, with high absorption of solar radiation at shorter wavelengths, a prerequisite for active photochemistry of dissolved organic matter.Land-fast ice in the Baltic also greatly alters the mixing characteristics of river waters flowing into coastal waters. River plumes extend under the ice to a much greater distance, and with greater stability than in ice-free conditions. Under-ice plumes not only alter the mixing properties of the waters, but also result in changed ice growth dynamics, and ice biological assemblages, with the underside of the ice being encased, in the extreme case, with a frozen freshwater layer.There is a pronounced gradient in ice types from more saline ice in the south to freshwater ice in the north. The former is characteristically more porous and supports more ice-associated biology than the latter. Ice conditions also vary considerably in different parts of the Baltic Sea, with ice persisting for over half a year in the northernmost part of the Baltic Sea, the Bothnian Bay. In the southern Baltic Sea, ice appears only during severe winters. |
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Granskog: Arctic Centre, University of Lapland, P.O. Box 122, FI-96101 Rovaniemi, Finland |
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Elsevier Science BV |
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Amsterdam |
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0272-7714 |
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Baltic Sea |
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Review |
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refbase @ admin @ Granskog++2006 |
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738 |
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Thomas, D.N.; Dieckmann, G.S. |
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Title |
Biogeochemistry of Antarctic sea ice |
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Journal Article |
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2002 |
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Oceanography and Marine Biology: An Annual Review |
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Oceanogr Mar Biol Annu Rev |
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40 |
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143-169 |
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Keywords |
Sea ice; Biogeochemistry; Nutrients (mineral); Dissolved gases; Dissolved organic matter; Ps; Antarctic Ocean |
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Abstract |
Antarctic sea ice at its maximum extent in winter covers 40% of the Southern Ocean in a frozen layer, on average, 1 m thick. Sea ice is not solid, rather it is an ice crystal matrix permeated by a labyrinth of brine filled channels and pores in which life thrives. Organisms are constrained by a set of physicochemical factors quite unlike anything they encounter in the plankton from where they are recruited. Because sea ice is increasingly viewed as a suitable proxy for life in previous periods of the Earth's history, and even for astrobiology, it is pertinent that the physicochemical constraints acting upon sea-ice biology are better understood. The, largely microbial, network that develops in the ice itself imparts a unique chemistry that influences the nature and chemical composition of biogenic material released from the ice. This chemistry can result in the export of material to the sediments with distinctive chemical signatures that are useful tools for reconstructing past sea-ice cover of the oceans. This review synthesises information on inorganic nutrient, dissolved organic matter and dissolved gases from a variety of Antarctic ice habitats. |
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Taylor & Francis |
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London |
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Gibson, R.N.; Barnes, M.; Atkinson, R.J.A. |
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0415254620 |
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Review; Marine |
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refbase @ admin @ Thomas+Dieckmann2002 |
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758 |
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Herborg, L.-M.; Thomas, D.N.; Kennedy, H.; Haas, C.; Dieckmann, G.S. |
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Title |
Dissolved carbohydrates in Antarctic sea ice |
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Journal Article |
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Year |
2001 |
Publication |
Antarctic Science |
Abbreviated Journal |
Antarct Sci |
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13 |
Issue |
2 |
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119-125 |
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Doc; Mcho; Pcho; sea ice; bacteria; carbon cycling; diatoms; dissolved organic carbon; monocarbohydrates; polycarbohydrates |
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Concentrations of dissolved monocarbohydrates (MCHO) and polycarbohydrates (PCHO) were analysed in a variety of ice habitats from summer Weddell Sea sea ice (surface ponds, ice cores, gap layers and platelet ice). The dissolved organic carbon (DOC) pool in these habitats was also measured and the contribution of carbohydrate to this pool was assessed. The DOC concentrations within all sea ice habitats were high compared to surface seawater concentrations with values up to 958µMC being measured. Total carbohydrates (TCHO) were highest in the ice cores and platelet ice samples, up to 3 1% of the DOC pool, a reflection of the high algal biomass in these two habitat classes. TCHO in the other habitats ranged between 10% and 29% of DOC. The ratios of MCHO to PCHO varied considerably between the ice habitats: in surface ponds and ice cores MCHO was 70% of the TCHO pool, whereas in gap layers and platelet ice there were lower PCHO concentrations resulting in MCHO being 88% of TCHO. |
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refbase @ admin @ Herborg++2001 |
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743 |
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Granskog, M.A.; Kaartokallio, H.; Thomas, D.N.; Kuosa, H. |
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Title |
Influence of freshwater inflow on the inorganic nutrient and dissolved organic matter within coastal sea ice and underlying waters in the Gulf of Finland (Baltic Sea) |
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Journal Article |
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2005 |
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Estuarine, Coastal and Shelf Science |
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Estuar Coast Shelf Sci |
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65 |
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1-2 |
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109-122 |
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coastal oceanography; sea ice; river plumes; estuarine chemistry; nutrients (mineral); dissolved organic matter; Baltic Sea |
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A study was conducted to measure the biogeochemical characteristics of freshwater plumes underlying Baltic Sea land-fast ice, and the overlying sea ice. A 40-km long transect was conducted in the northern Baltic Sea in March 2003, following a freshwater plume from its source into the fully mixed open-sea area. The spreading of river outflow below the ice resulted in a well-stratified low-salinity surface layer further out than normally occurs in the open-water period. The freshwaters were high in dissolved organic matter (DOC, DON and CDOM), and inorganic nutrients (ammonium, nitrate and silicate), although the levels of phosphate were low. In general these parameters changed concurrently with salinity in such a way that mixing was conservative. The characteristics of the ice varied from the freshwater source to the open water, with increasing salinity and brine volumes (porosity) occurring in the more open-sea stations. Coinciding with the changes in ice properties there was an increase in sea-ice algal growth in the more marine stations along the transect. Biological activity in the ice was largely confined to bottom ice assemblages. In contrast to the conditions in the underlying water, no relationship between salinity, inorganic nutrients and organic matter was observed in the ice. In particular ammonium, phosphate, DOC and DON were present in excess of those levels predicted from the dilution curves, indicating the presence of considerable DOM production by ice assemblages, inorganic nutrient uptake and remineralization within the ice. |
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Academic Press |
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San Diego |
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Sampling: Nine stations along a 40km salinity gradient from inner Pojo Bay through the Archipelago to the edge of the open sea |
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refbase @ admin @ Granskog++2005_2 |
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740 |
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