Polar Biology最新文献

iKaluk, Inuttitut for Arctic charr (Salvelinus alpinus), holds significant commercial and cultural value for Inuit communities throughout Nunatsiavut. Studies evaluating iKaluk habitat associations in freshwater are plentiful; however, there is limited information on the ecological makeup and sediment characteristics of anadromous charr habitats in marine environments. This study investigated the benthic associations of Arctic charr during their marine residency period in Nain, Nunatsiavut, using underwater videos, harvester-identified fishing locations, and acoustic telemetry. Drop-camera surveys were deployed on previously placed hydrophone acoustic receivers and within harvester-identified fishing locations to describe and quantify available benthic habitats in the study area. Telemetry information was used to identify charr occupancy hotspots, and calculate habitat suitability indices. A total of 248,056 benthic organisms belonging to 63 morphotaxa were identified within the 125 video drops used for benthic community characterization and these represented five faunal assemblages. Marine phase charr occupied estuaries to a greater degree than other fjord or coastal headland environments and these habitats were typically characterized by fine sediments covered by high densities of brittle stars (Ophiuroidea spp.) and benthic diatom mats. The consistent presence of diatomaceous sediments is indicative of abundant foraging opportunities. The importance of these habitats to iKaluk, need to be considered in future marine planning given the cultural and ecological value of this species to many northern communities that face growing threats from environmental change.

Supplementary information: The online version contains supplementary material available at 10.1007/s00300-024-03323-z.

Knowledge of the spatial distribution of many polar seabird species is incomplete due to the remoteness of their breeding locations. Here, we compiled a new database of published and unpublished records of all known snow petrel Pagodroma nivea breeding sites. We quantified local environmental conditions at sites by appending indices of climate and substrate, and regional-scale conditions by appending 30 year mean (1992-2021) sea-ice conditions within accessible foraging areas. Breeding snow petrels are reported at 456 sites across Antarctica and subantarctic islands. Although many counts are old or have large margins of error, population estimates available for 222 known sites totalled a minimum of ~ 77400 breeding pairs. However with so many missing data, the true breeding population will be much higher. Most sites are close to the coast (median = 1.15 km) and research stations (median = 26 km). Median distance to the November sea-ice edge (breeding season sea-ice maximum) is 430 km. Locally, most nests occur in cavities in high-grade metamorphic rocks. Minimum air temperatures occur at inland sites, and maxima at their northern breeding limit. Breeding location and cavity selection is likely determined by availability of suitable breeding substrate within sustainable distance of suitable foraging habitat. Within this range, nest sites may then be selected based on local conditions such as cavity size and aspect. Our database will allow formal analyses of habitat selection and provides a baseline against which to monitor future snow petrel distribution changes in response to climate change.

Small ponds and lakes and their surrounding riparian zone are ecological hot spots in the Arctic landscape. They are important for biogeochemical cycling and habitats for terrestrial and aquatic organisms. Arctic birds may have strong impact on these small aquatic ecosystems. In particular, the increasing populations of Arctic geese are strongly associated with ponds and can significantly influence the physico-chemical properties and ecological communities of these waterbodies. Birds supply nutrients via feces, grubbing and physical disturbance leading to increased erosion and run-off. We examined how the pond ecosystems, including phytoplankton and zooplankton communities respond to increased bird impact. Six ponds on Svalbard differentially impacted by birds were sampled in summer 2022. Bird-impacted ponds were characterized by higher nutrient concentrations, especially of phosphorus. They also had significantly higher phytoplankton biomass with a different phytoplankton community. Although mixotrophic species constituted a substantial part of the community in all ponds, we observed increased dominance of both cryptophytes and cyanobacteria at high bird impact. High bird impact was also associated with low metazoan zooplankton abundance and high ciliate abundance. Phytoplankton and metazoan zooplankton taxa richness was much lower in the most impacted pond compared to the other waterbodies. Bird impact did not significantly relate to diffusive CO₂ and methane fluxes from the ponds. Thus, high bird impact was associated with hypereutrophic pond conditions characterized by decreased diversity and a likely stimulation of the microbial loop. The results may hint at some of the future changes in Arctic ecosystems in ponds increasingly influenced by birds.

Supplementary information: The online version contains supplementary material available at 10.1007/s00300-025-03426-1.

The coastal region of the Western Antarctic Peninsula is considered a biological hotspot with high levels of phytoplankton productivity and krill biomass. Recent in situ observations and particle modeling studies of Palmer Canyon, a deep bathymetric feature in the region, demonstrated the presence of a recirculating eddy that traps particles, retaining a distinct particle layer over the summer season. We applied metagenomic sequencing and Imaging Flow Cytobot (IFCB) analysis to characterize the microbial community in the particle layer. We sampled across the upper water column (< 200 m) along a transect to identify the locations of increased particle density, categorizing particles into either living cells or cellular detritus via IFCB. An indicator species analysis of community composition demonstrated the diatom Corethron and the bacteria Sulfitobacter were significantly highly abundant in samples with high levels of living cells, while the mixotrophic dinoflagellate Prorocentrum texanum and prokaryotes Methanomassiliicoccales and Fluviicola taffensis were significantly more abundant in samples with high detritus within the particle layer. From our metagenomic analysis, the significantly differentially abundant metabolic pathway genes in the particle layer of Palmer Canyon included pathways for anaerobic metabolism, such as methanogenesis and sulfate reduction. Overall, our results indicate that distinct microbial species and metabolic pathway genes are present in the retained particle layer of Palmer Canyon.

Supplementary information: The online version contains supplementary material available at 10.1007/s00300-025-03380-y.

While the Southern Ocean represents a unique habitat, currently undergoing rapid environmental change, its biodiversity remains largely unknown, particularly at greater depths. Increased sampling efforts in the Amundsen Sea, a previously unexplored region of the Southern Ocean, combined with the use of an epibenthic sledge resulted in a large collection of mobile, scale-bearing worms from the family Polynoidae Kinberg, 1856. The greatest taxonomic novelty in the material collected from the Pine Island Bay, Amundsen Sea, was found within the exclusively deep-sea subfamily Macellicephalinae Hartmann-Schröder, 1971. Examination of this material has already led to formalization of six new species of Macellicephala (Neal et al. 2018). This study represents the continuation of such effort with formalization of Macellicephaloides veronikae sp. n. based on morphology and 16S and 18S molecular markers. In the phylogenetic analyses, the new species is sister taxon to Macellicephaloides moustachu from the abyssal equatorial Pacific Ocean, albeit based on very limited taxon sampling currently available. Macellicephaloides veronikae sp. n. shows the shallowest distribution (500-1000 m) of this genus recorded to date and may represent a case of polar emergence.

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.