Search results for "Arctic Regions"
showing 9 items of 59 documents
F-type lectin from serum of the Antarctic teleost fish Trematomus bernacchii (Boulenger, 1902): Purification, structural characterization, and bacter…
2021
Abstract The increasing availability of sequenced genomes has enabled a deeper understanding of the complexity of fish lectin repertoires involved in early development and immune recognition. The teleost fucose-type lectin (FTL) family includes proteins that preferentially bind fucose and display tandemly arrayed carbohydrate-recognition domains (CRDs) or are found in mosaic combinations with other domains. They function as opsonins, promoting phagocytosis and the clearance of microbial pathogens. The Antarctic fish Trematomus bernacchii is a Perciforme living at extremely low temperatures (−1.68 °C) which is considered a model for studying adaptability to the variability of environmental w…
Total mercury and methyl-mercury contents and accumulation in polar microbial mats.
2014
Although polar regions are considered isolated and pristine areas, the organisms that inhabit these zones are exposed to global pollution. Heavy metals, such as mercury, are global pollutants and can reach almost any location on Earth. Mercury may come from natural, volcanic or geological sources, or result from anthropogenic sources, in particular industrial or mining activities. In this study, we have investigated one of the most prominent biological non-marine communities in both polar regions, microbial mats, in terms of their Hg and methyl-mercury (MeHg) concentrations and accumulation capacities. The main hypotheses posed argued on the importance of different factors, and to test them…
Recent evolution of the multi-isotopic radioactive content in ice of Livingston Island, Antarctica.
1999
The temporal arrangement of the ice layers that are produced in ecosystems with perpetual snows form situations that greatly favour the study of the temporal evolution of the radioactive fallout that occurs in the said zones, whether this fallout is natural or artificial in origin. This allows one to investigate the causes of the fallout and the mechanisms transporting the radionuclides involved from their source point to the study zone, as well as their subsequent behaviour in that zone. There are special difficulties involved in this type of study in Antarctica. Some are of a general character deriving from the conditions of extreme climate and isolation which complicate the processes of …
The trophic transfer of persistent pollutants (HCB, DDTs, PCBs) within polar marine food webs.
2017
Biomagnification (increase in contaminant concentrations at successively higher levels of trophic web), is a process that can transversally impair biodiversity and human health. Most research shows that biomagnification should be higher at poles with northern sites having a major tendency to biomagnify Persistent Organic Pollutants (POPs) through their marine food webs. We investigated the biomagnification degree into two marine trophic webs combining carbon and nitrogen stable isotopes and POP analyses. We showed that the Antarctic trophic web was more depleted than the sub-Arctic one and the differences highlighted for the basal part could explain the difference in length between them. Co…
Horizontal and vertical food web structure drives trace element trophic transfer in Terra Nova Bay, Antarctica
2019
Abstract Despite a vast amount of literature has focused on trace element (TE) contamination in Antarctica during the last decades, the assessment of the main pathways driving TE transfer to the biota is still an overlooked issue. This limits the ability to predict how variations in sea-ice dynamics and productivity due to climate change will affect TE allocation in the food web. Here, food web structure of Tethys Bay (Terra Nova Bay, Ross Sea, Antarctica) was first characterised by analysing carbon and nitrogen stable isotopes (δ13C, δ15N) in organic matter sources (sediment and planktonic, benthic and sympagic primary producers) and consumers (zooplankton, benthic invertebrates, fish and …
Trace elements and stable isotopes in penguin chicks and eggs: A baseline for monitoring the Ross Sea MPA and trophic transfer studies.
2021
Multi-tissue trace elements (TEs), C, N concentrations and stable isotopes (δ13C, δ15N) of chick carcasses and eggs of Adelie and Emperor penguins were studied to i) provide reference data before the recent institution of the Ross Sea Marine Protected Area (Antarctica), and ii) provide conversion factors that allow estimating C, N, δ13C and δ15N in edible tissues from non-edible ones, thus improving the use of stable isotopes in contamination and trophic transfer studies. Higher concentrations of As, Cd, Cr, Cu, Hg, Mn and Pb were found in chick carcasses than in eggs, suggesting increasing contamination in recent decades and high toxicity risks for penguin consumers. Isotopic conversion fa…
Natural and artificial radioactivity levels in Livingston Island (Antarctic regions).
1994
Radioactive contamination of the sea and land is due, on the one hand, to fallout from atmospheric atomic explosions since 1945, and, on the other, to emissions produced by nuclear and radioactive facilities. Given its geographic position far distant from the aforementioned main sources of radioactive contamination, Antarctica should have the lowest levels that can be measured on the Earth of artificial radionuclides in the various receptor media which are characteristic of the trophic chain. In the case of Antarctica, these are melt-water, sea-water, mosses, algae, and lichens. With the aim of contributing basic information on the radiation levels present in the Antarctic ecosystem, we hav…
Could the acid-base status of Antarctic sea urchins indicate a better-than-expected resilience to near-future ocean acidification?
2015
13 pages; International audience; Increasing atmospheric carbon dioxide concentration alters the chemistry of the oceans towards more acidic conditions. Polar oceans are particularly affected due to their low temperature, low carbonate content and mixing patterns, for instance upwellings. Calcifying organisms are expected to be highly impacted by the decrease in the oceans' pH and carbonate ions concentration. In particular, sea urchins, members of the phylum Echinodermata, are hypothesized to be at risk due to their high-magnesium calcite skeleton. However, tolerance to ocean acidification in metazoans is first linked to acid–base regulation capacities of the extracellular fluids. No infor…
The origin of heavy metals and radionuclides accumulated in the soil and biota samples collected in Svalbard, near Longyearbyen
2017
Heavy metals and radioactive compounds are potentially hazardous substances for plants, animals and humans in the Arctic. A good knowledge of the spatial variation of these substances in soil and primary producers, and their sources, is therefore essential. In the samples of lichen Thamnolia vermicularis, Salix polaris and Cassiope tetragona, and the soil samples collected in 2014 in Svalbard near Longyearbyen, the concentrations of the following heavy metals were determined: Mn, Ni, Cu, Zn, Cd, Pb and Hg, as well as the activity concentrations of the following: K-40, Cs-137, Pb-210, Pb-212, Bi-212, Bi-214, Pb-214, Ac-228, Th-231 and U-235 in the soil samples. The differences in the concent…