Polar Biology最新文献

The diversity of bacteria associated with lichens has received increasing attention. However, studies based on next-generation sequencing of microbiomes have not yet been conducted in the Arctic and Subarctic regions. In this study, rock-dwelling lichens belonging to the Umbilicariaceae family were sampled from the Arctic and Subarctic biological zones. The primary research purpose was to undertake a comparative investigation of the bacterial composition and diversity, identify potential indicators, and explore their potential metabolic pathways. 18S rRNA gene sequences of the fungal partner belonging to the genus Umbilicaria (Ascomycota) and the algal partner affiliated with the lineage Trebouxia (Chlorophyta). Comparing Umbilicaria spp. with a previous study in the Antarctic zone, the fungal partners were more inclined to cluster by sampling region. Operational taxonomic units (OTUs) were established based on a predetermined similarity threshold for V3-V4 sequences, which were ascribed to 19 bacterial phyla, and ten of them were consistently present in all samples. The most distinct zonal indicator genera based on OTU frequencies from Arctic and Subarctic lichens were Capsulimonas (Armatimonadota) and Jatrophihabitans (Actinomycota), respectively. Although the Subarctic zone had higher biodiversity and species richness based on alpha-diversity, the beta-diversity showed that the main species of bacterial communities were not significantly different, and the predictions of metabolic pathways based on the bacterial microbiome in lichen samples from the two zones were similar. These findings provide evidence that the geographical and/or bioclimatic environment and the different lichen-forming fungal species mainly and partially influence bacterial microbiomes and metabolic pathways.

Supplementary information: The online version contains supplementary material available at 10.1007/s00300-024-03303-3.

Abstract

Cryobacterium spp. are Gram-positive bacteria that inhabit diverse geographical locations, particularly extremely cold environments like the Polar Regions. However, strategies that enable them to survive in harsh Antarctic environments are not fully understood. In this study, we conducted a comparative genomic analysis of the Antarctic Cryobacterium sp. SO2 as well as other members of the Cryobacterium genus. Phylogenetic analysis revealed that strain SO2 formed a distinct cluster with the validly described species: C. adonitolivorans, C. actose, C. soli, C. arcticum, and C. zongtaii. Comparative analysis based on ANI and AAI indicated that strain SO2 is a novel species. Relative Synonymous Codon Usage (RSCU) of Cryobacterium species exhibits a bias towards codon ending with G/C. The genomes of all strains harbored numerous genes associated with environmental-associated stress responses, including oxidative stress response, general stress response, heat-stress response, cold-stress response, cell envelope alteration, and osmotic stress response. Strain SO2 and related strains possess genes involved in breaking down and utilization of both plant and animal carbohydrate-containing materials. KEGG annotation indicated that strain SO2 and related species shared almost the same genes for the metabolism of trehalose (TreS, partial TPS/TPP, and TreY-TreZ pathway) and glycogen (classical and non-classical pathway). The results from this work helped us to better understand the genomic characteristics of Cryobacterium spp. in terms of genomic diversity and adaptation strategies, which may have significant implications for biotechnology and climate change research.

The nesting site of Magellanic penguins (Spheniscus magellanicus) at Tucker islets (54°09'S; 70°17'W), Chile, is documented and information from the first population abundance estimate on the largest islet during the beginning of chick rearing is provided. Ground-based counts yielded an estimate of 8883 (95% Confidence Intervals: 6653–11,802) burrows; however, counts of active burrows resulted in a total estimate of 2218 (95% Confidence Intervals: 1593–2840) breeding pairs. Based on the estimated total of burrows, this suggests a population decline consistent with trends for other colonies in the Magellan Strait and adjacent waters in Chile. An annual monitoring program to track population changes, breeding success, and chick and egg survival rates is required to assess the species' conservation status of the colony.

Abstract

The fish community of the Scotia Sea is diverse and plays key roles in Antarctic food webs and biogeochemical cycling. However, knowledge of the spatial and community structure of their early life stages is limited, particularly in the region surrounding the South Orkney Islands. Here we examine the structure of the early life stage fish community in the epipelagic using data from a basin-scale survey conducted in early 2019, which sampled the top 200 m of the water column. 347 early life stage fish from 19 genera were caught in 58 hauls. A third of all specimens belonged to the genus Notolepis and the nine most common genera comprised over 90% of specimens. Cluster analysis revealed five distinct groupings, the most common were a group dominated by pelagic and shelf slope genera (Notolepis, Muraenolepis and Electrona) found mainly in oceanic waters (depth ≥ 1000 m), and a group dominated by species with demersal or benthopelagic adults (Chionodraco, Chaenocephalus and Nototheniops) found mainly in shelf waters. Bottom depth was the main environmental determinant of community structure, separating the diverse on-shelf assemblage at the South Orkneys from the less species-rich community of widespread oceanic taxa. Our results indicate the highest diversities of early life stages of endemic fish occur on the shelf and near-shelf areas. Dedicated monitoring is recommended to understand the seasonal differences in larval community assemblages and the implications of early life stages fish bycatch within the krill fishery.

Pink salmon, Oncorhynchus gorbuscha (Walbaum, 1792), a native of the North Pacific Ocean, is an invasive fish species rapidly expanding in the North Atlantic, the adjacent waters of the Arctic Ocean, and rivers in their watersheds. We investigated the species composition of parasites and the structure of parasite communities of the introduced pink salmon in Kandalaksha Bay of the White Sea in 2021. The parasites were identified using morphological and genetic methods. A total of 14 parasite species were recorded. The core species of the parasitic fauna of the introduced pink salmon in the Kandalaksha Bay were Clistobothrium sp., ʽDiphyllobothriumʼ spp., Scolex polymorphus Rudolphi, 1819 (plerocercoids), Brachyphallus crenatus (Rudolphi, 1802), Derogenes varicus (Müller, 1784), Lecithaster salmonis Yamaguti, 1934 (adults), Anisakis simplex (Rudolphi, 1809) sensu stricto (juvenile III), and Hysterothylacium aduncum (Rudolphi, 1802) (juveniles III and IV). We provided the first evidence that the Pacific genetic lineage of A. simplex sensu stricto occurs in European marine waters. In 2021, there was a noticeable increase in the mean abundance of the third-stage juveniles of Anisakis in the White Sea pink salmon compared to the period of 1990s-early 2000s. We conclude that the pink salmon occupies the same trophic niche in the new region of its introduction as in the native range.

The Antarctic continent hosts life forms specially adapted to the extreme climatic challenges. Among these organisms are nematodes, key organisms in the cycling of nutrients in soil food webs. These organisms are bioindicators of environmental disturbances, making their study essential for assessing the impact of human activity in this unique ecosystem. The Carlini Station and the Antarctic Specially Protected Area 132 on the 25 de Mayo/King George Island, Antarctica, has seen limited investigation of free-living soil nematodes. This study aimed to analyze free-living nematode communities in pristine soils and anthropic-intervened soils in the Carlini Station area. Nematodes were extracted from soil samples and morphologically identified at the genus and family levels to calculated ecological indices to assess nematode community structure. Ecological indices (abundance, maturity, enrichment, and soil food structure) were calculated and their values were compared between anthropic and pristine sites using the ANOSIM, SIMPER, and ANOVA statistical tests. Additionally, using molecular analysis, a phylogenetic study was conducted. The study identified four nematode genera, including Plectus spp., Calcaridorylaimus spp., Eudorylaimus spp., and Coomansus spp., with Plectus spp. being the most abundant and widely distributed. Anthropic sites had lower maturity and higher enrichment values, indicative of disturbance, while pristine sites exhibited higher maturity and structure values, suggesting a healthier soil food web. These results suggest that anthropic intervention disrupts nematode communities and represent a significant contribution to the understanding of free-living nematode communities in Antarctica.

This study presents the pattern of occurrence of sub-Antarctic fur seals (SAFS), Arctocephalus tropicalis, in the southern Brazilian coast and evaluate its association with climatic variability and anomalies in the concentration of chlorophytes and sea surface temperature in the reproductive colonies of Gough and Tristan da Cunha Islands. Date, sex, and age class of 254 stranded SAFS recorded between 1992 and 2013 were analyzed. Representative indexes of the patterns of climatic variability and environmental variables were obtained between four and five months before the records, the assumed interval of displacement for species between their closest breeding colonies and the southern Brazilian coast. The species was observed in southern Brazil between May and November each year, and most individuals were adult males. The records of SAFS on the southern Brazilian coast were associated with low concentration of chlorophytes interacting with negative sea surface temperature anomalies, and positive events of South Annular Mode, South Atlantic Ocean Dipole and Indian Ocean Dipole. Climatic variability is influencing the ecology SAFS, because it affects the environmental factors, that act as a driver of dispersion of the species. These variables had been interacting together in the region of the breeding colonies, and possibly during the fur seals’ journey towards the Brazilian coast. Considering the current scenario of global climate change, we expect that SAFS will continue to disperse to areas beyond their regular distribution, not only in the direction of the coasts of southern continents, but also further south, towards higher latitudes.

Carrion decomposition contributes to the soil microbial community structure. This research aimed to identify the soil arthropod, nematode, bacterial, and fungal communities associated with penguin carrion on King George Island, Antarctica. Soil samples were collected around and beneath fresh (freshly killed penguins by the predators) and dried (decomposed more than a year) penguin carrion. Soil bacterial and fungal communities associated with the penguin carrion were analyzed using the 16S rRNA and internal transcribed spacer (ITS) gene sequencing, respectively. Arthropod identification was using Sanger sequencing and nematodes were determined using morphological identification. This study demonstrated no significant differences in arthropod and nematode, bacteria, and fungi communities between decomposition stages, soil location, and species of penguin carrion. This is the first study to identify soil arthropods, nematodes, bacterial, and fungal communities associated with penguin carrion, offering important insights into the initial documentation of the necrobiome communities in the polar region.

Understanding the energy requirement and prey consumption of Arctic predators is crucial to assess their vulnerability to climate change. The bowhead whale (Balaena mysticetus) is the largest predator of the Arctic, with Disko Bay in Greenland constituting a major feeding ground for a segment (predominantly larger juveniles and adult non-lactating females) of the Eastern Canada-West Greenland population. We used unmanned aerial vehicle photogrammetry to measure the body size and condition of bowhead whales in Disko Bay during the spring (March 26–June 1, 2022), from which we quantified their energy requirements and prey consumption. Measurements of body length, width and height were used to estimate the body volume and condition of juveniles (50 measurements from 39 individuals) and adults (232 measurements from 154 individuals). The body condition of adults increased at a rate of 0.112 percentage points day⁻¹, or 44.1–87.8 L of blubber day⁻¹ (for lengths 13.0–17.0 m). Using published data from harvested whales, the estimated blubber mass gain was 37.1–73.9 kg day⁻¹, which equals an energy deposition rate of 1.01–2.01 GJ day⁻¹. Body maintenance costs were predicted from allometric models, while activity costs and the heat increment of feeding were derived from published archival tag data. Reported length-at-age curves were used to estimate somatic growth costs. The energy requirements for juveniles and adults were 0.621–0.778 GJ day⁻¹ (for lengths 11.0–12.9 m) and 3.662–7.826 GJ day⁻¹ (for lengths 13.0–17.0 m), respectively, which equals a prey consumption rate of 17–22 kg of prey day⁻¹ (0.1% of body mass) and 102–218 kg day⁻¹ (0.3% of body mass).