Polar Biology最新文献

Species of Eatoniellidae are typical members of shallow, cold waters of the Southern Hemisphere; however, very little is known about their biology. This work deals with the first description of spawns and developmental stages for the family. All samples were collected from Southern Argentina and were identified as Eatoniella turricula based on shell, opercular, and radular characters. Spawn is composed by a globose, thick-walled capsule with a single egg/embryo surrounded by nutritive liquid which allows direct development. E. turricula is a very small species, with limitation to the energy available for reproduction and inhabiting in cold water implying a low metabolic and growth rate. The species is expected to produce few eggs, thereby increasing the possibilities of survival by allocating available energy to generate an abundant food supply within a thick-walled capsule that provides strong protection. This strategy resulted comparable to other microgastropods from cold water suggesting that evolved many times independently and convergently. The distribution of Eatoniellidae is also discussed considering its direct development as well as the geographical changes occurred in Southern areas during the last 20 millions of years, including the ongoing development of the Antarctic Circumpolar Current.

The novel concept of the review is a focus on the organisms living in the sea ice and what mechanisms they have developed for their existence. The review describes the physical environment of the sea ice and the microorganisms living there as microalgae, bacteria, virus, fungi, meio- and macrofauna where they inhabit the brine channels and exposed to low temperatures as down to −25 °C and high salinities—up to 300. Nutrients, O₂, CO₂, pH, light, and UV are also identified as stressors regarding the metabolism of the microorganisms. It is argued that sea ice must be recognized as an extreme environment as based on records of very high or very low concentrations or intensities of the stressors that living organisms in the ice are exposed to and able to endure. Each taxonomic group of organisms in the sea ice are dealt with in detail in terms of the explicit stressors the group is exposed to, and specifically what known mechanisms that the organisms have amended to secure existence and life. These mechanisms are known for some group of organisms as autotrophs, bacteria, meio- and macrofauna but less so for virus and fungi. The review concludes that sea ice is an extreme environment where the stressors vary significantly in both space and time, both in consort and solitary, classifying organisms living there as polyextremophiles and extremophiles. The review relates further to extraterrestrial moons covered with sea ice and these habitats and points toward sea ice on Earth for prospective studies until further technological advances.

The southern right whale dolphin, Lissodelphis peronii (Lacépède, 1804), is a species of cetacean that is distributed in cold and deep waters throughout the Southern Hemisphere, with records in coastal waters of the western Atlantic Ocean being extremely rare. On January 7, 2019, a specimen still alive, was recorded entangled in a fishing gillnet on the beach at Cardoso Beach (28°44′S, 48°58′W), in the state of Santa Catarina, on the southern coast of Brazil. The recording was made by a lifeguard using a GoPro camera and was made available through citizen science. The animal was untangled and released while still alive and was not found stranded again after the date of the event. Based on existing literature, this is the second record of the species in Brazilian waters. Analyzing meteorological and oceanographic features from the days preceding the record, it was not possible to make any association between the entanglement and the variables analyzed, and no explanatory driver could therefore be established for this unusual event.

Natural resource development in the Canadian Arctic—a mostly remote and ‘untouched’ landscape—is expanding. Raptorial species are key indicators of ecosystem diversity and environmental change; disturbance-mediated changes to Arctic-breeding raptor populations can be assessed to determine impacts from development. From 2012 through 2020, we monitored peregrine falcon (Falco peregrinus) and rough-legged hawk (Buteo lagopus) breeding territories near an iron ore mine on North Baffin Island, Nunavut, Canada. The mine was constructed from 2010 through 2014 and became operational in 2015. Our objective was to evaluate whether proximity to mining disturbance affected occupancy and reproductive success of both species. We quantified occupancy using multi-season occupancy models and reproductive success using stochastic partial differential equations capable of accounting for unexplained spatiotemporal variation. Occupancy of both species was best explained by year effects. Occupancy remained relatively stable across time for peregrine falcons ((lambda) = 0.99 ± 0.04) but fluctuated drastically for rough-legged hawks ((lambda) = 3.41 ± 2.17). For both species, most of the spatiotemporal variation in reproductive success was unexplained (presumably from underlying abiotic and biotic factors), which led to the differential presence and count of nestlings across the study area and time. Neither distance to disturbance nor primary production explained variation in occupancy and reproductive success.

Glacial retreat due to global warming is exposing large tracts of barren glacial sediments that are quickly colonized by CO₂-fixing microbial communities that can constitute the climax community in many high-Arctic, alpine, and Antarctic environments. Despite the potential importance of these processes, little is known about microbial community successional dynamics and rates of carbon (C) sequestration in environments where higher plants are slow or unable to establish. We analyzed microbial community succession and C and N accumulation in newly exposed sediments along an Antarctic glacial chronosequence where moss and microbial autotrophs are the dominant primary producers. During the first 4 years of succession (0 to 40 m from the glacier) algae (including diatoms) were the most relatively abundant eukaryotes, but by the second phase studied (8 to 12 years) moss amplicon sequence variants (ASVs) dominated. The rise in moss coincided with a significant buildup of C and N in the sediments. The final two phases of the successional sequence (16 to 20 and 26 to 30 years) were marked by declines in microbial species richness and moss relative abundance, that coincided with significant decreases in both total C and N. These retrogressive declines coincided with a large increase in relative abundance of predatory Vampyrellidae suggesting a possible mechanism for retrogression in this and perhaps other terrestrial ecosystems at the edge of the cryosphere. These findings have implications for understanding CO₂ sequestration and ecosystem succession in microbial-dominated regions of the cryobiosphere where large tracts of land are currently undergoing deglaciation.

The diet of the Antarctic shags was investigated at Paradise Bay, Antarctic Peninsula, by the analysis of 20 pellets collected during the 2015/16 breeding season. Fish were the most frequent and important prey, accompanied by Polychaetes. Amongst fish, only benthic-demersal species were represented in the diet. Harpagifer antarcticus, followed by Notothenia coriiceps, was the most frequent prey and the most important by number and mass. The results are compared with the diet reported for this shag at other localities of the South Shetland Islands and of the Antarctic Peninsula and discussed in terms of geographical significance, breeding output, and population trend.

Female Weddell seals (Leptonychotes weddellii) display a mixed capital-income breeding strategy, losing up to 40% of their body mass between birthing and weaning their pups. How and when they regain energy stores, however, remains to be fully explored. To better understand the foraging by lactating Weddell seals, we fitted time-depth recorders and head-mounted cameras on 26 seals in Erebus Bay, Ross Sea, for ~ 5 days in November and December 2018 and 2019. We aimed to (1) identify prey species and foraging depth and (2) investigate relationships between seal physiology and demographics and probability of foraging. We recorded 2782 dives, 903 of which were > 50 m, maximum depth was 449.3 m and maximum duration was 31.1 min. Pup age likely contributes to the probability of a lactating Weddell seal foraging (Est. = 1.21 (SD = 0.61), z = 1.97, p = 0.0484). Among 846 prey encounters, the most frequent prey items were crustaceans (46.2%) and Antarctic silverfish (Pleuragramma antarcticum, 19.0%); two encounters were observed with juvenile Antarctic toothfish (Dissostichus mawsoni, 0.2%). We identified substantial variability in foraging behaviour, individually and between locations, and found that lactating seals target many species and some may specialise on certain prey groups.

Under the "One Health" concept, this paper aims to explore the occurrence of antimicrobial resistance in Enterobacterales (i.e., Escherichia coli and Salmonella enterica) among the South American Sea Lions on Argentina's northern Patagonian coast. From 177 fecal samples collected, conventional protocols were used to isolate E. coli and S. enterica. Antimicrobials classified as critically important by the WHO were evaluated by disk diffusion and agar spot (colistin) methods. Molecular tools were used to detect mcr genes as needed. A total of 176 antimicrobial-susceptible E. coli strains and 14 S. enterica strains were recovered. Twelve E. coli strains were colistin resistant (agar spot positive) but PCR negative for the mcr-1 to mcr-5 genes. Whole-genome sequencing revealed a chromosomal mutation, coding for Val161Gly change in PmrB protein, as the colistin resistance mechanism in one of these isolates. This study provides knowledge on AMR surveillance in wildlife associated with the marine environment in South America.

Gvozdarus svetovidovi (Nototheniidae) is the rarest notothenioid fish, represented by only two specimens collected in 1970 and 1988. As it is little known, we present aspects of the cranial osteology of this species and use this, and other features of its morphology, to infer fundamental aspects of its biology. As in other pelagic nototheniids, G. svetovidovi has an elongated neurocranium and jaws but it does not have a paedomorphic skeleton. Although not unique to G. svetovidovi, the bones of the skull have some well-developed ridges for support and possibly for containment of subcutaneous fat. The skeleton is most similar to that of Dissostichus. G. svetovidovi has a high fat content, primarily within the trunk musculature and in a layer over the skull. It is probably neutrally buoyant in mesopelagic waters, where it has been captured at 295–550 m depth north of the Antarctic Slope Front (approximately the shelf break) and south of the southern boundary of the Antarctic Circumpolar Current. It likely relies on vision and mechanosensation to detect its prey, including bioluminescent, energy-dense myctophids and krill in this resource-rich area of the Southern Ocean. Strays near shelf waters feed on Pleuragramma antarcticum. G. svetovidovi is unlike all other notothenioids in fundamental aspects of its biology including its habitat, diet and distribution. Although it may be on the path to extinction, if our postulated life history of G. svetovidovi is accurate, it expands the current perception of the bounds of the notothenioid radiation into a locality in the Southern Ocean not previously known to be occupied by this group.