Description: Polar bears ( Ursus maritimus ) are apex predators of the Arctic, which exposes them to an array of natural and anthropogenic stress factors. Metabolomics analysis profiles endogenous metabolites that reflect the response of biological systems to stimuli, and the effects of multiple stressors can be assessed from an integrated perspective. A targeted, quantitative, liquid chromatography–mass spectrometry-based metabolomics platform [219 metabolites including amino acids, biogenic amines, acylcarnitines, phosphatidylcholines (PCs), sphingomyelins, hexoses (Hex), and fatty acids (FAs)] was applied to the muscle and liver of polar bears from the Southern and Western Hudson Bay (Canada) subpopulations (SHB and WHB, respectively). Multivariate statistics were then applied to establish whether bears were discriminated by sex and/or subpopulation. Five metabolites identified by variable importance projection (VIP) discriminated the hepatic profiles of SHB males and females (Hex, arginine, glutamine, one PC, one sphingomyelin), while fifteen metabolites (primarily PCs along with leucine) contrasted the livers of males from SHB and WHB. Metabolite profiles in the muscle of male and female bears could not be differentiated; however, the muscles of SHB and WHB males were discriminated primarily by PCs and FAs. Stable isotope ratios (δ 13 C and δ 15 N) were variably related to metabolites; δ 13 C was correlated with some VIP metabolite concentrations, particularly in comparisons of male bears from SHB and WHB, suggesting an influence of dietary differences. However, δ 15 N and age exhibited few, relatively weak correlations with metabolites. The metabolite profiles discriminating the sexes and subpopulations may have utility for future assessments regarding the effects of specific stressors on the physiology of Hudson Bay polar bears.

Description: Persistent organic pollutant (POP) contamination of Polar Regions continues to present a major ecological challenge and an environmental stressor to local biota. Antarctic krill (Euphausia superba) are a keystone species of the Antarctic sea ice ecosystem. Krill have repeatedly been found to accumulate a diverse array of POPs and thereby serve as vectors of these to the remainder of the Antarctic food web. p , p ′-Dichlorodiphenyldichloroethylene ( p , p ′-DDE) is a dominant POP compound accumulating in Antarctic krill and higher trophic level predators. Recently, p , p ′-DDE uptake dynamics, associated behavioural and developmental toxicity were evaluated in this species. The present study investigated the response of enzymes with known roles in detoxification (glutathione S -transferase, GST and cytochrome P450 2B, CYP2B), neurotoxicity (acetylcholinesterase, AChE) and oxidative stress (glutathione peroxidase GPx) in Antarctic krill exposed to p , p ′-DDE. CYP2B was not detectable in Antarctic krill. No strong concentration responses resulted from the exposure to p , p ′-DDE. These findings do not provide evidence for an activated detoxification response to this compound via the tested biochemical pathways in Antarctic krill. This is the first time that GST, AChE and GPx have been characterised in this species following pollutant exposure. Further research with additional pollutants and compound mixtures is necessary to assess the practical role of these enzymes as biomarkers of pollutant exposure in Antarctic krill. These first exploratory findings present a valuable contribution to a critical knowledge gap in polar ecotoxicology, namely the comparative sensitivity of polar organisms relative to temperate and tropical counterparts.

Description: Soil microbes play important roles in global carbon and nutrient cycling. Soil microfungi are generally amongst the most important contributors. They produce various extracellular hydrolase enzymes that break down the complex organic molecules in the soil into simpler form. In this study, we investigated patterns of amylase and cellulase (which are responsible for breaking down starch and cellulose, respectively) relative activity (RA) on solid media at different culture temperatures in fungal strains from Arctic, Antarctic and tropical soils. Fungal isolates from all three regions were inoculated onto R2A media supplemented with starch for amylase and carboxymethylcellulose and trypan blue for cellulase screening. The isolates were then incubated at 4, 10, 15, 20, 25, 30, 35 and 40 °C and examined for activity after 5 and 10 days, for tropical and polar isolates, respectively. The data obtained indicate that the polar fungal strains exhibited similar patterns of amylase and cellulase RA. Both Arctic and Antarctic fungi showed highest RA for amylase and cellulase at 35 °C, while colony growth was maximised at 15 °C. Colony growth and RA of the polar isolates were negatively correlated suggesting that, as temperatures increase, the cells become stressed and have fewer resources available to invest in growth. Unlike polar isolates, tropical isolates did not exhibit any trend of colony growth with temperature, rather having idiosyncratic patterns in each isolate. The low enzyme production and RA levels in the tropical strains may suggest both a low ability to respond to temperature variation in their natural thermally stable tropical habitats, as well as a level of thermal stress limiting their enzyme production ability.

Description: Competition between individuals of the same or different species affects spatial distribution of organisms at any given time. Consequently, a species geographical distribution is related to population dynamics through density-dependent processes. Small Arctic rodents are important prey species in many Arctic ecosystems. They commonly show large cyclic fluctuations in abundance offering a potential to investigate how landscape characteristics relates to density-dependent habitat selection. Based on long-term summer trapping data of the Norwegian lemming ( Lemmus lemmus ) in the Scandinavian Mountain tundra, we applied species distribution modeling to test if the effect of environmental variables on lemming distribution changed in relation to the lemming cycle. Lemmings were less habitat specific during the peak phase, as their distribution was only related to primary productivity. During the increase phase, however, lemming distribution was, in addition, associated with landscape characteristics such as hilly terrain and slopes that are less likely to get flooded. Lemming habitat use varied during the cycle, suggesting density-dependent changes in habitat selection that could be explained by intraspecific competition. We believe that the distribution patterns observed during the increase phase show a stronger ecological signal for habitat preference and that the less specific habitat use during the peak phase is a result of lemmings grazing themselves out of the best habitat as the population grows. Future research on lemming winter distribution would make it possible to investigate the year around strategies of habitat selection in lemmings and a better understanding of a fundamental actor in many Arctic ecosystems.

Description: Studies investigating viral ecology have mainly been conducted in temperate marine and freshwater habitats. Fewer reports are available on the often less accessible “extreme environments” such as hot springs. This study investigated prokaryotic- and virus-like particles (VLP) associated to hot springs, themselves situated in cold environments of the Southern Hemisphere (i.e. in the French Southern and Antarctic Lands). This was performed by examining their abundance in hot springs and surrounding temperate seawater using both epifluorescence microscopy (EFM) and flow cytometry (FCM), which was applied for the first time to such ecosystems. On one hand, prokaryotic abundances of 4.0 × 10 5 –2.2 × 10 6  cell mL −1 and 7.0 × 10 4 –2.8 × 10 6  cell mL −1 were measured using EFM and FCM, respectively. The abundances of virus-like particles (VLP), on the other hand, ranged between 9.8 × 10 5 and 7.5 × 10 6 particles mL −1 when using EFM, and between 1.3 × 10 5 and 6.2 × 10 6 particles mL −1 when FCM was applied. A positive correlation was found between VLP and prokaryotic abundances, while the virus-to-prokaryote ratio was generally low and ranged between 0.1 and 6. In parallel, samples and culture supernatants were also visualised using transmission electron microscopy. For this, enrichment cultures were prepared using environmental samples. Both raw sample and enrichment culture—supernatants were analysed for the presence of VLPs. Observations revealed the presence of Caudovirales, membrane vesicles and possibly a new type of virion morphology, associated to members of the order Thermotogales, a thermophilic and anaerobic bacterium.

Description: Although research on parasitic diseases in Antarctic birds is scarce and the information largely fragmented, an increasing number of studies are currently in progress in this area. The host/parasite relationship is very important for understanding the impact of parasitism on the seabirds’ feeding ecology, especially in those isolated regions where the host is extremely sensitive to new diseases. Penguins are a big favorite for these studies because of their importance as indicators of change in the Antarctic ecosystem. This study aims at adding information on gastrointestinal parasites of the Emperor Penguin Aptenodytes forsteri from Snow Hill colony. Based on a sample of 43 individuals found freshly dead (3 adults and 40 chicks) from predation or starvation, the gastrointestinal helminth community in Emperor penguins was composed of two species of cestodes ( Parorchites zederi and Tetrabothrius sp.) and three species of nematodes ( Stegophorus macronectes, Tetrameres sp. and Contracaecum osculatum ). This is the first record of S. macronectes in the Emperor Penguin. The low parasite richness observed might be related to the stenophagic and pelagic diet of this host.

Description: The authors regret an error in the published article, where incorrect data was used to produce Figure 2, showing the temporal development of pH over the duration of the experiment. The corrected Fig. 2 shows that the error did not affect the interpretation of nor the conclusions drawn from the present dataset. The original article has been corrected.

Description: An integrative inventory of the amphipod scavenging fauna (Lysianassoidea), combining morphological identifications with DNA barcoding, is provided here for the Filchner area situated in the south-eastern Weddell Sea. Over 4400 lysianassoids were investigated for species richness and relative abundances, covering 20 different stations and using different sampling devices, including the southernmost baited traps deployed so far (76°S). High species richness was observed: 29 morphospecies of which 5 were new to science. Molecular species delimitation methods were carried out with 109 cytochrome c oxidase I gene (COI) sequences obtained during this study as well as sequences from specimens sampled in other Antarctic regions. These distance-based analyses (trees and the Automatic Barcode Gap Discovery method) indicated the presence of 42 lineages; for 4 species, several (cryptic) lineages were found. More than 96% of the lysianassoids collected with baited traps belonged to the species Orchomenella pinguides s. l. The diversity of the amphipod scavenger guild in this ice-bound ecosystem of the Weddell Sea is discussed in the light of bottom–up selective forces. In this southernmost part of the Weddell Sea, harbouring spawning and nursery grounds for silverfish and icefishes, abundant fish and mammalian food falls are likely to represent the major food for scavengers. Finally, the importance of biodiversity surveys in the context of the establishment of a marine protected area in this region (Weddell Sea MPA) is highlighted and how future studies can contribute to a better understanding the ecological role of scavengers in this system is discussed.

Description: The original article shows TDFe in Table 1 as µmol L −1 . The correct TDFe in Table 1 should be nmol L −1 .

Description: Records of vagrant marine organisms provide important information on oceanographic anomalies and the changing environment. We report on an immature Weddell seal, Leptonychotes weddellii , sighted at Calheta Beach in Trindade Island (20°31′S 29°19′W), Brazil, on July 9, 2015. A number of injuries were noted, including blisters on the dorsal surface of the body and a small cut at the right-hand side distal portion of the mandible. Based on its size and the state of fusion of cranial sutures, we suggest that it was born in the 2014 austral spring and was possibly 8–10 months old. We suggest that it comes from the South Shetland Islands, Antarctic Peninsula. This is the closest breeding location of this species. This sighting is the northernmost of L. weddellii , being at least ~ 5140 km from the Antarctic Peninsula (63°12′S 55°04′W) and ~ 2840 km north from the second northernmost sighting of this species in Uruguay.