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Title |
Abiotic degradation of highly branched isoprenoid alkenes and other lipids in the water column off East Antarctica |
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Journal |
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Year |
2019 |
Publication |
Marine Chemistry |
Abbreviated Journal |
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Volume |
210 |
Issue |
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Pages |
34-47 |
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Keywords |
Alteration of IPSO/HBI III ratio East Antarctica Lipids Near-surface sediments Paleoceanographic implications Photo- and autoxidation Suspended particulate matter |
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Abstract |
In some previous studies, the ratio between a di-unsaturated highly branched isoprenoid (HBI) lipid termed IPSO25 and a structurally related tri-unsaturated counterpart (HBI III) (viz. IPSO25/HBI III) has been used as a proxy measure of variable sea ice cover in the Antarctic owing to their production by certain sea ice algae and open water diatoms, respectively. To investigate this further, we quantified selected lipids and their photo- and autoxidation products in samples of suspended particulate matter (SPM) collected at different water depths in the polynya region west of the Dalton Iceberg Tongue (East Antarctica). The results obtained confirm the high efficiency of photo- and autoxidation processes in diatoms from the region. The systematic increase of the ratio IPSO25/HBI III with water depth in the current samples appeared to be dependent on the sampling site and was due to both (i) a relatively higher contribution of ice algae to the deeper samples resulting from their increased aggregation and therefore higher sinking rate, or (ii) a stronger abiotic degradation of HBI III during settling through the water column. Analyses of samples taken from the water-sediment interface and some underlying near-surface sediments revealed a further increase of the ratio IPSO25/HBI III, indicative of further differential oxidation of the more unsaturated HBI. Unfortunately, specific oxidation products of HBI III could not be detected in the strongly oxidized SPM and sediment samples, likely due to their lability towards further oxidation. In contrast, oxidation products of HBI III were detected in weakly oxidized samples of phytoplanktonic cells collected from Commonwealth Bay (also East Antarctica), thus providing more direct evidence for the involvement of photo- and/or autoxidation of HBI III in the region. This oxidative alteration of the ratio IPSO25/HBI III between their source and sedimentary environments might need to be considered more carefully when using this parameter for palaeo sea ice reconstruction purposes in the Antarctic. |
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1010 |
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0304-4203 |
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yes |
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8141 |
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Author |
Torsten Wappler, Thomas Denk |
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Title |
Herbivory in early Tertiary Arctic forests |
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Journal |
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Year |
2011 |
Publication |
Palaeogeography, Palaeoclimatology, Palaeoecology |
Abbreviated Journal |
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Volume |
310 |
Issue |
3 |
Pages |
283-295 |
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Abstract |
Early Tertiary High Arctic forest ecosystems are unique in that they have no equivalent among modern forests. Today, no forest ecosystem exists at such high latitudes. To assess the potential role of herbivory during the early Tertiary warm period at high latitudes, we have surveyed 1567 fossil angiosperm leaves from Svalbard for the presence or absence of 35 insect damage types (DTs). Our investigation for the first time uncovered a wealth of insect trace fossils from the early Tertiary northern high latitudes. These include galls, mines, and feeding traces on fossil leaves. Most of the folivory includes unspecific external foliage feeding that cannot be ascribed to a particular group of insects. Exceptions are the mining damage types that are most similar to those made by leaf-mining moths (Lepidoptera: Gracillaroidea). Nevertheless, the abundance of folivory indicates that herbivorous insects were an important component of the forests thriving in the Arctic realm. The observed change in insect herbivory from the Middle Paleocene to the Late Eocene/Early Oligocene in Spitsbergen may be attributed to climatic variables because they influence insect life-cycle timing, population density, and geographic range. |
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1005 |
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0031-0182 |
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yes |
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8140 |
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Title |
Wasp mimicry among Palaeocene reduviid bugs from Svalbard |
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Year |
2013 |
Publication |
Acta palaeontologica polonica |
Abbreviated Journal |
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Volume |
58 |
Issue |
4 |
Pages |
883-887 |
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1005 |
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ISSN |
05677920 |
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yes |
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8139 |
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Title |
Morphological and molecular insights on Megalothorax: the largest Neelipleona genus revisited (Collembola) |
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Journal |
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Year |
2013 |
Publication |
Invertebrate Systematics |
Abbreviated Journal |
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Volume |
27 |
Issue |
3 |
Pages |
317-364 |
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Abstract |
The genus Megalothorax Willem, 1900 is redefined along with a redescription of the type species M. minimus Willem, 1900 and the description of five new species (M. granulosus, sp. nov., M. nigropunctatus, sp. nov., M. perspicillum, sp. nov., M. svalbardensis, sp. nov. and M. willemi, sp. nov.). We describe and comment on broad sets of discriminating characters for Megalothorax systematics. For the first time, trichobothria are recorded for Neelipleona, probably of generic importance. The described species are provided with DNA data (COI, 16S and 28S) and included in a molecular-based phylogenetic analysis. The traditional distinction between minimus-group and incertus-group is discussed in the light of DNA and morphology components. A key to the worldwide Megalothorax species is provided. |
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1005 |
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1447-2600, 1447-2600 |
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yes |
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Serial |
8138 |
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Author |
Christopher M. Berry, John E.A. Marshall |
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Title |
Lycopsid forests in the early Late Devonian paleoequatorial zone of Svalbard |
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Journal |
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Year |
2015 |
Publication |
Geology |
Abbreviated Journal |
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Volume |
43 |
Issue |
12 |
Pages |
1043-1046 |
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1005 |
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ISSN |
0091-7613 |
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yes |
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8137 |
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Title |
A multiproxy evaluation of Holocene environmental change from Lake Igaliku, South Greenland |
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Year |
2012 |
Publication |
Journal of Paleolimnology |
Abbreviated Journal |
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Volume |
48 |
Issue |
1 |
Pages |
241-258 |
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1004 |
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ISSN |
1573-0417 |
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yes |
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8136 |
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Title |
Use of palmitoleic acid and its oxidation products for monitoring the degradation of ice algae in Arctic waters and bottom sediments |
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Journal |
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Year |
2018 |
Publication |
Organic geochemistry |
Abbreviated Journal |
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Volume |
124 |
Issue |
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Pages |
88-102 |
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Keywords |
Arctic Biotic and abiotic degradation Palmitoleic acid Sea ice Sinking particles Superficial bottom sediments Sympagic algae |
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Abstract |
Degradation of palmitoleic acid (C16:1?7), the main fatty acid component of sea ice-associated (sympagic) diatoms, was monitored in Arctic sea ice at the beginning of ice melting and in the underlying sinking particles and superficial bottom sediments. In sea ice, degradation of sympagic algae involved biotic oxidation induced by 10S-DOX-like lipoxygenase of unknown salinity-stressed attached bacteria, while photo- and autoxidation were limited. In the water column, strong hydratase and Z/E isomerase activity were observed. Hydration of unsaturated fatty acids seems to be a detoxification strategy, which is essential for bacterial survival when associated with free fatty acid-rich environments such as ice algae. In contrast, Z/E isomerisation of palmitoleic acid was attributed to the release of Fe2+ ions during radical-induced damage of the active site of the bacterial 10S-DOX-like lipoxygenase and Z/E isomerases. Due to the poor physiological state of their attached bacteria resulting from salinity stress in brine channels or toxicity of free ice algae fatty acids, sympagic algae appeared to be only very weakly biotically degraded within the water column. In bottom sediments, free radicals resulting from 10S-DOX-like lipoxygenase activity induced a strong autoxidation of the ice algal material. The presence in bottom sediments of a significant proportion of oxidation products resulting from 10S-DOX-like lipoxygenase activity attested to the strong contribution of sea ice-derived OM released during the early stages of ice melt prior to deposition in the sediments. However, on the basis of the highest fatty acid photooxidation state observed in these sediments, an additional contribution of highly photooxidized material (ice algal material released at the end of ice melting or open water phytoplankton) seems likely. The degradation of hydroperoxides, resulting from biotic and abiotic degradation of palmitoleic acid, appeared to involve: (i) homolytic cleavage of the peroxyl group affording the corresponding hydroxy- and oxoacids, (ii) reduction to the corresponding hydroxyacids by peroxygenases, (iii) heterolytic proton-catalysed cleavage and (iv) conversion to allylic 1,4-diols by diol synthases and hydroperoxide isomerases. |
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1164 |
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ISSN |
0146-6380 |
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yes |
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8135 |
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Title |
High Angular Resolution Measurements of the Anisotropy of Reflectance of Sea Ice and Snow |
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Journal |
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Year |
2018 |
Publication |
Earth and Space Science |
Abbreviated Journal |
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Volume |
5 |
Issue |
1 |
Pages |
30-47 |
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Keywords |
Arctic bidirectional reflectance reflectance anisotropy remote sensing snow and ice albedo spectroradiometry |
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1164 |
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ISSN |
2333-5084 |
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yes |
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Serial |
8134 |
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Title |
Copepod Grazing Influences Diatom Aggregation and Particle Dynamics |
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Journal |
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Year |
2019 |
Publication |
Frontiers in Marine Science |
Abbreviated Journal |
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Volume |
6 |
Issue |
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Pages |
751 |
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1164 |
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ISSN |
2296-7745 |
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yes |
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8133 |
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Title |
Late spring bloom development of pelagic diatoms in Baffin Bay |
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Journal |
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Year |
2019 |
Publication |
Elementa: science of the anthropocene |
Abbreviated Journal |
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Volume |
7 |
Issue |
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Pages |
44 |
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1164 |
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ISSN |
2325-1026 |
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yes |
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Call Number |
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8132 |
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