Antarctic strict anaerobic microbiota from <Emphasis Type="Italic">Deschampsia antarctica</Emphasis> vascular plants rhizosphere reveals high ecology and biotechnology relevance

The Antarctic soil microbial community has a crucial role in the growth and stabilization of higher organisms, such as vascular plants. Analysis of the soil microbiota composition in that extreme environmental condition is crucial to understand the ecological importance and biotechnological potential. We evaluated the efficiency of isolation and abundance of strict anaerobes in the vascular plant Deschampsia antarctica rhizosphere collected in the Antarctic’s Admiralty Bay and associated biodiversity to metabolic perspective and enzymatic activity. Using anaerobic cultivation methods, we identified and isolated a range of microbial taxa whose abundance was associated with Plant Growth-Promoting Bacteria (PGPB) and presences were exclusively endemic to the Antarctic continent. Firmicutes was the most abundant phylum (73 %), with the genus Clostridium found as the most isolated taxa. Here, we describe two soil treatments (oxygen gradient and heat shock) and 27 physicochemical culture conditions were able to increase the diversity of anaerobic bacteria isolates. Heat shock treatment allowed to isolate a high percentage of new species (63.63 %), as well as isolation of species with high enzymatic activity (80.77 %), which would have potential industry application. Our findings contribute to the understanding of the role of anaerobic microbes regarding ecology, evolutionary, and biotechnological features essential to the Antarctic ecosystem.     

Production of enzymes and antimicrobial compounds by halophilic Antarctic <Emphasis Type="Italic">Nocardioides</Emphasis> sp. grown on different carbon sources

This study demonstrated the potential of microbial isolates from Antarctic soils to produce hydrolytic enzymes by using specific substrates. The results revealed potential of the strains to produce a broad spectrum of hydrolytic enzymes. Strain A-1 isolated from soil samples in Casey Station, Wilkes Land, was identified as Nocardioides sp. on the basis of morphological, biochemical, physiological observations and also chemotaxonomy analysis. Enzymatic and antimicrobial activities of the cell-free supernatants were explored after growth of strain A-1 in mineral salts medium supplemented with different carbon sources. It was found that the carbon sources favored the production of a broad spectrum of enzymes as well as compounds with antimicrobial activity against Gram-positive and Gram-negative bacteria, especially Staphylococcus aureus and Xanthomonas oryzae. Preliminary analysis showed that the compounds with antimicrobial activity produced by the strain A-1 are mainly glycolipids and/or lipopeptides depending on the used carbon source. The results revealed a great potential of the Antarctic Nocardioides sp. strain A-1 for biotechnological, biopharmaceutical and biocontrol applications as a source of industrially important enzymes and antimicrobial/antifungal compounds.     

Cold-adapted yeasts from Antarctica and the Italian Alps—description of three novel species: Mrakia robertii sp. nov., Mrakia blollopis sp. nov. and Mrakiella niccombsii sp. nov.

Worldwide glaciers are annually retreating due to global overheating and this phenomenon determines the potential lost of microbial diversity represented by psychrophilic microbial population sharing these peculiar habitats. In this context, yeast strains, all unable to grow above 20°C, consisting of 42 strains from Antarctic soil and 14 strains isolated from Alpine Glacier, were isolated and grouped together based on similar morphological and physiological characteristics. Sequences of the D1/D2 and ITS regions of the ribosomal DNA confirmed the previous analyses and demonstrated that the strains belong to unknown species. Three new species are proposed: Mrakia robertii sp. nov. (type strain CBS 8912), Mrakia blollopis sp. nov. (type strain CBS 8921) and a related anamorphic species Mrakiella niccombsii sp. nov. (type strain CBS 8917). Phylogenetic analysis of the ITS region revealed that the new proposed species were closely related to each other within the Mrakia clade in the order Cystofilobasidiales, class Tremellomycetes. The Mrakia clade now contains 8 sub-clades. Teliospores were observed in all strains except CBS 8918 and for the Mrakiella niccombsii strains.     

Temperature effects and fatty acid patterns in Geomyces species isolated from Antarctic soil

Summary Geomyces and Chrysosporium species isolated from Antarctica were compared with a strain isolated from Italian soil. The Italian and Antarctic strains had different growth rates and membrane fatty acids at different temperatures.     

Size scaling of photophysiology and growth in four freshly isolated diatom species from Ryder Bay,western Antarctic peninsula

Diatoms are one of the dominant groups in phytoplankton communities of the western Antarctic Peninsula (WAP). Although generally well‐studied, little is known about size dependent photophysiological responses in diatom bloom formation and succession. To increase this understanding, four Antarctic diatom species covering two orders of magnitude in cell size were isolated in northern Marguerite Bay (WAP). Fragilariopsis sp., Pseudo‐nitzschia cf. subcurvata, Thalassiosira cf. antarctica, and Proboscia cf. alata were acclimated to three different irradiances after which photophysiology, electron transport, carbon fixation, and growth were assessed. The small species Fragilariopsis sp., Pseudo‐nitzschia cf. subcurvata, and large species Proboscia cf. alata showed similar photoacclimation to higher irradiances with a decrease in cellular chlorophyll a and an increase in chlorophyll a specific absorption and xanthophyll cycle pigments and activity. In contrast, pigment concentrations and absorption remained unaffected by higher irradiances in the large species Thalassiosira cf. antarctica. Overall, the small species showed significantly higher growth rates compared to the large species, which was related to relatively high light harvesting capacity and electron transport rates in the smaller species. However, photophysiological responses related to photoinhibition and photoprotection and carbon fixation showed no relationship with cell size. This study supports the dominance of small diatoms at low irradiances during winter and early spring, but does not provide photophysiological evidence for the dominance of large diatoms during the phytoplankton bloom in the WAP. This suggests that other factors such as grazing and nutrient availability are likely to play a major role in diatom bloom formation.     

Retrotransposon‐based genetic diversity of Deschampsia antarctica Desv. from King George Island (Maritime Antarctic)

Deschampsia antarctica Desv. can be found in diverse Antarctic habitats which may vary considerably in terms of environmental conditions and soil properties. As a result, the species is characterized by wide ecotypic variation in terms of both morphological and anatomical traits. The species is a unique example of an organism that can successfully colonize inhospitable regions due to its phenomenal ability to adapt to both the local mosaic of microhabitats and to general climatic fluctuations. For this reason, D. antarctica has been widely investigated in studies analyzing morphophysiological and biochemical responses to various abiotic stresses (frost, drought, salinity, increased UV radiation). However, there is little evidence to indicate whether the observed polymorphism is accompanied by the corresponding genetic variation. In the present study, retrotransposon‐based iPBS markers were used to trace the genetic variation of D. antarctica collected in nine sites of the Arctowski oasis on King George Island (Western Antarctic). The genotyping of 165 individuals from nine populations with seven iPBS primers revealed 125 amplification products, 15 of which (12%) were polymorphic, with an average of 5.6% polymorphic fragments per population. Only one of the polymorphic fragments, observed in population 6, was represented as a private band. The analyzed specimens were characterized by low genetic diversity (uH_e = 0.021, I = 0.030) and high population differentiation (F_ST = 0.4874). An analysis of Fu's F_S statistics and mismatch distribution in most populations (excluding population 2, 6 and 9) revealed demographic/spatial expansion, whereas significant traces of reduction in effective population size were found in three populations (1, 3 and 5). The iPBS markers revealed genetic polymorphism of D. antarctica, which could be attributed to the mobilization of random transposable elements, unique features of reproductive biology, and/or geographic location of the examined populations.     

Characterization of a novel antarctic plant growth-promoting bacterial strain and its interaction with antarctic hair grass (Deschampsia antarctica Desv)

Deschampsia antarctica is the only hair grass that has been able to successfully colonize the Antarctic continent. However, there is little research on the role of microorganisms associated with the rhizosphere that may participate in its growth and development. The objective of this research was to characterize a psychrotolerant bacterial strain isolated from the rhizosphere of D. antarctica. Biochemical and molecular studies were performed to characterize this bacterium. It was determined that this strain secretes a neutral polysaccharide that presents different compositions at different temperatures (4 and 20 °C). Based on biochemical and phylogenetic analyses, the Antarctic rhizobacterium could be a new species of Pseudomonas. To determine their ability to solubilize different sources of inorganic phosphate, qualitative and quantitative analyses were conducted to determine P released at 4 °C. The Antarctic strain of Pseudomonas sp. was able to solubilize all sources of phosphates, and 34.2 mg P/L was released from rock phosphate. Growth physiological parameters were evaluated for seedlings of D. antarctica inoculated with the rhizobacteria. It was found that the bacterial inoculation promoted plant root development. SEM analysis of the roots showed that the bacterium is mainly located in the root hairs of D. antarctica.     

POLYPHASIC STUDY OF ANTARCTIC CYANOBACTERIAL STRAINS1

We isolated 59 strains of cyanobacteria from the benthic microbial mats of 23 Antarctic lakes, from five locations in two regions, in order to characterize their morphological and genotypic diversity. On the basis of their morphology, the cyanobacteria were assigned to 12 species that included four Antarctic endemic taxa. Sequences of the ribosomal RNA gene were determined for 56 strains. In general, the strains closely related at the 16S rRNA gene level belonged to the same morphospecies. Nevertheless, divergences were observed concerning the diversity in terms of species richness, novelty, and geographical distribution. For the 56 strains, 21 operational taxonomic units (OTUs, defined as groups of partial 16S rRNA gene sequences with more than 97.5% similarity) were found, including nine novel and three exclusively Antarctic OTUs. Sequences of Petalonema cf. involvens and Chondrocystis sp. were determined for the first time. The internally transcribed spacer (ITS) between the 16S and the 23S rRNA genes was sequenced for 33 strains, and similar groupings were observed with the 16S rRNA gene and the ITS, even when the strains were derived from different lakes and regions. In addition, 48 strains were screened for antimicrobial and cytotoxic activities, and 17 strains were bioactive against the gram‐positive Staphylococcus aureus, or the fungi Aspergillus fumigatus and Cryptococcus neoformans. The bioactivities were not in coincidence with the phylogenetic relationships, but rather were specific to certain strains.     

Vegetation cover regulates the quantity,quality and temporal dynamics of dissolved organic carbon and nitrogen in Antarctic soils

Populations of the two native Antarctic vascular plant species (Deschampsia antarctica and Colobanthus quitensis) have expanded rapidly in recent decades, yet little is known about the effects of these expansions on soil nutrient cycling. We measured the concentrations of dissolved organic carbon (DOC) and nitrogen (DON), amino acids and inorganic N in soils under these two vascular plant species, and under mosses and lichens, over a growing season at Signy Island in the maritime Antarctic. We recorded higher concentrations of nitrate, total dissolved nitrogen, DOC, DON and free amino acids in soil under D. antarctica and C. quitensis than in lichen or moss dominated soils. Each vegetation cover gave a unique profile of individual free amino acids in soil solution. Significant interactions between soil type and time were found for free amino acid concentrations and C/N ratios, indicating that vascular plants significantly change the temporal dynamics of N mineralization and immobilization. We conclude that D. antarctica and C. quitensis exert a significant influence over C and N cycling in the maritime Antarctic, and that their recent population expansion will have led to significant changes in the amount, type and rate of organic C and N cycling in soil.     

Cryptococcus adeliensis sp. nov., a xylanase producing basidiomycetous yeast from Antarctica

Cryptococcus adeliensis sp. nov. (CBS 8351) is described based on phenotypic characteristics and molecular sequence analysis of the D1/D2 large subunit and internal transcribed spacer regions of the ribosomal DNA. Molecular comparisons include species closely related to Cryptococcus albidus and several species isolated from the Antarctic. C. adeliensis, which has a cold-adapted xylanase, was isolated from Terre Adelie, Antarctica. ATCC 34633, which has a mesophilic xylanase, was identified as Cryptococcus albidosimilis.     

Purple-Pigmented Violacein-Producing <Emphasis Type="Italic">Duganella</Emphasis> spp. Inhabit the Rhizosphere of Wild and Cultivated Olives in Southern Spain

Bacteria have evolved mechanisms that allow them to grow and survive in highly competitive environments like soil and the rhizosphere. Using classical microbiological, physiological, and genetic analyses, we isolated and identified for the first time Duganella spp. associated with the rhizosphere of woody plants in Mediterranean environments that are able to produce violacein, a blue–purple secondary metabolite of considerable biotechnological interest. Based on physiological and biochemical characterization and phylogenetic analysis of different genes including 16S rRNA, gyrB, and vioA (implicated in the synthesis of violacein), the seven Duganella spp. strains isolated and studied were differentiated according to their host of origin (wild versus cultivated olives) and potentially might belong to new species. All the Duganella spp. strains produced violacein in vitro, with natural production levels significantly higher than that previously reported for other violacein-producing bacteria without optimizing growing conditions. The important biological, medical, and industrial applications of violacein make these bacteria good candidates for their biotechnological exploitation because low violacein yields are considered as one of the main limitations of using wild-type strains for extensive exploitation and pigment production. Independent of violacein production, purple-pigmented strains from olives showed proteolytic and lipolytic activities and a weak siderophore production. No in vitro inhibitory activity was demonstrated for bacteria or crude violacein filtrates against plant-pathogenic Gram-negative bacteria and fungi, but they did inhibit Gram-positive bacteria.     

A critical review of Antarctic Conoidea (Neogastropoda)

ABSTRACT

The Antarctic Conoidean fauna is critically reviewed based on published data and specimens in the collections of the USNM, IORAS and MNHN. Forty-two species and subspecies of the superfamily Conoidea are recorded as occurring within the Antarctic Convergence (excluding the fauna of the Kerguelen Islands) and are attributed to 14 genera and seven families. These include the new taxa: Antarctospira n. gen. (type species—Leucosyrinx badenpowelli Dell, 1990); Drilliola antarctica n. sp.; Pleurotomella (Pleutoromella) tippetti n. sp.; Pleurotomella (Anomalotomella) petiti n. sp.; Xanthodaphne pastorinoi n. sp. Aforia watsoni is introduced as a new name for Pleurotoma (Surcula) lepta Watson, 1881, non Pleurotoma lepta Edwards, 1861. A lectotype is designated for Conorbella antarctica (Strebel, 1908). New combinations are also proposed. Antarctospira badenpowelli (Dell, 1990), n. comb. (previously assigned to Leucosyrinx); Antarctospira principalis (Thiele, 1912), n. comb. (previously assigned to Typhlomangelia); Antarctospira mawsoni (Powell, 1958), n. comb. (previously assigned to Leucosyrinx); Typhlodaphne paratenoceras (Powell, 1951), n. comb. (previously assigned to Leucosyrinx); Belalora weirichi (Engl, 2008), n. comb. (previously assigned to Oenopota); Pleurotomella (Anomalotomella) innocentia (Dell, 1990), n. comb. (previously assigned to Typhlodaphne); Pleurotomella (Anomalotomella) nipri (Numanami, 1996), n. comb. (previously assigned to Typhlodaphne); Xanthodaphne raineri (Engl, 2008), n. comb. (previously assigned to Pleurotomella); Aforia hedleyi (Dell, 1990), n. comb. (previously assigned to Pontiothauma). The majority of Antarctic conoidean taxa have hypodermic marginal teeth. Although there is a similar relative abundance of conoideans in Antarctic waters to that seen in other well-studied faunas, the low number of conoideans is indicative of the general impoverishment of the gastropod fauna in the region. Fourteen percent (2 of 14) of conoidean genera that occur within the Antarctic Convergence are endemic to Antarctic waters, as are 82% (34 of 42) of the species. Most taxa have very broad bathymetric ranges, some extending from bathyal to hadal depths. The greatest species diversity was at bathyal depths.     

Do Antarctic lichens modify microclimate and facilitate vascular plants in the maritime Antarctic? A comment to Molina‐Montenegro et al. ()

A recent article published by Molina‐Montenegro et al. (Journal of Vegetation Science24: 463) examines the association of Antarctic native plant and lichen species to the lichen Usnea antarctica on Fildes Peninsula, King George Island, maritime Antarctica. The authors report that on two sites, five out of 13 and four out of 11 species of lichens and mosses were spatially associated with U. antarctica, suggesting positive interactions between them. Although Deschampsia antarctica does not grow naturally associated with U. antarctica, Molina‐Montenegro et al. carried out a transplantation experiment to demonstrate that the macrolichen acts as a nurse plant, improving the survival of the grass. Serious conceptual and methodological discrepancies emerge from a critical evaluation of this study, challenging their conclusions. First, we suspect that the author confused some lichen taxa, and we also disagree with macrolichens being treated as cushion plants, because rootless, poikilohydric and poikilothermic thallophytes such as lichens are unable to create a stable, enclave‐like microhabitat as vascular cushion plants do. Indeed, a critical evaluation of some of the micro‐environmental parameters measured indicates that there are no biologically meaningful differences between the U. antarctica thalli and surrounding open areas. Second, the lack of consideration of the life history of the species under study leads to confusion when (a) referring to the succession sequence of species that colonize the studied area and (b) interpreting the putative distribution patterns promoted by Usnea versus the substrate preferences of associated species. Third, the authors intend to demonstrate experimentally that Usnea can facilitate the survival of D. antarctica plants, transplanting adult plants and not seedlings between the lichen thalli, and it is not clear how the grass was planted – between or within the lichens – as at both experimental sites the lichens grow on stones or rocks. Facilitative interactions are present in the Antarctic and may play a pivotal role in the structure and functioning of the fragile Antarctic ecosystems. However, more rigorous and well‐planned research is needed to assess its presence, importance and involved mechanisms.     

南极乔治王岛冰锥洞微生物培养探索

【目的】南极洲具备独特的环境和相对的生物地理隔离,南极洲各类生境中蕴藏了大量尚未培养和难培养的微生物,也是新颖微生物物种的重要来源之一。本研究以南极冰锥洞这类特殊生境为研究对象,通过培养条件的多样化提升南极微生物的培养率和多样性,揭示南极冰锥洞可培养微生物类群多样性,为该环境可培养微生物功能研究奠定基础,也为南极极端环境未培养微生物的培养方法提供借鉴。【方法】通过采用不同培养基添加复苏促进因子(resuscitation promoting factor, Rpf)的方式,提高南极柯林斯冰盖冰锥洞生境中微生物的可培养率,探究该生境中微生物的多样性。采用4种不同营养水平的培养基,平行添加Rpf进行菌株培养,经分离纯化与16S rRNA基因鉴定,分析冰锥洞可培养微生物的多样性及培养条件对多样性的影响。【结果】本研究共分离培养细菌407株,涵盖5个门、18个科、29个属,其中：放线菌门(Actinomycetota)为优势门,占72.73%;微杆菌科(Microbacteriaceae)为优势科,占69.78%;Lacisediminihabitans属为优势属,占45.70%。从培养基效果...     

Endophytic fungi associated with the Antarctic grass <Emphasis Type="Italic">Deschampsia antarctica</Emphasis> Desv. (<Emphasis Type="Italic">Poaceae</Emphasis>)

Deschampsia antarctica Desv. (Poaceae) represents one of the two vascular plants that have colonized the Antarctic continent, which is usually exposed to extreme environmental conditions. In this work, we have characterized the endophytic fungi associated with the leaves of D. antarctica. Endophytic fungi were recovered from 91 individual plants from different points of Admiralty Bay at King George Island, Antarctica. A total of 26 fungal isolates were obtained from 273 leaf fragments. All isolates were identified by analysis of the sequences of the internal transcribed spacer region (ITS) of the rDNA. Alternaria and Phaeosphaeria were the most frequent genera associated with the plant. Other fungal isolates were identified as Entrophospora sp. and several undescribed Ascomycete species. An interesting result was obtained for the isolates UFMGCB 215 and UFMGCB 262, which were related to fungi associated with bryophytes present in boreal ecosystems. Some isolates showed low identity in the ITS sequences to sequences of fungal species deposited in GenBank, suggesting that these fungi could be new species. This work is the first report on fungal endophytes associated with leaves of the Antarctic grass D. antarctica.     

Agarolytic culturable bacteria associated with three antarctic subtidal macroalgae

Bacterial communities of Antarctic marine macroalgae remain largely underexplored in terms of diversity and biotechnological applications. In this study, three Antarctic subtidal macroalgae (Himantothallus grandifolius, Pantoneura plocamioides and Plocamium cartilagineum), two of them endemic of Antarctica, were investigated as a source for isolation of agar-degrading bacteria. A total of 21 epiphytic isolates showed agarolytic activity at low temperature on agar plates containing agar as the sole carbon source. 16S rRNA identification showed that the agar-degrading bacteria belonged to the genera Cellulophaga, Colwellia, Lacinutrix, Olleya, Paraglaciecola, Pseudoalteromonas and Winogradskyella. The agarase enzyme from a potential new species of the genus Olleya was selected for further purification. The enzyme was purified from the culture supernatant of Olleya sp. HG G5.3 by ammonium sulfate precipitation and ion-exchange chromatography. Molecular weight of the agarase was estimated to be 38 kDa by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The purified enzyme exhibited activity at 4 °C, retaining >?50% of its maximum activity at this temperature. This is the first study reporting the phylogeny of agar-degrading bacteria isolated from Antarctic subtidal macroalgae and the results suggest the huge potential of Antarctic algae-associated bacteria as a source of cold-active hydrolytic enzymes of biotechnological interest.     

Effect of temperature on the growth rates of halotolerant and halophilic bacteria isolated from Antarctic saline lakes

Summary The effect of temperature on the growth rates of Halomonas subglaciescola and a Halobacterium sp., halotolerant and halophilic bacteria isolated from Antarctic saline lakes, was predicted accurately by models which propose a linear relationship between temperature and the square root of the reciprocal of the growth rate. The cardinal temperatures of the strains examined were in general 5–10°C lower than those of taxonomic counterparts isolated from temperate and tropical environments. Temperature dependence data for strains of the Halobacterium sp. and annual temperature profiles of Deep Lake allowed estimation of the in situ potential for growth.     

Bacterial diversity from benthic mats of Antarctic lakes as a source of new bioactive metabolites

During the MICROMAT project, the bacterial diversity of microbial mats growing in the benthic environment of Antarctic lakes was accessed for the discovery of novel antibiotics. In all, 723 Antarctic heterotrophic bacteria belonging to novel and/or endemic taxa in the α-, β- and γ-subclasses of the Proteobacteria, the Bacteroidetes branch, and of the high and low percentage G+C Gram-positives, were isolated, cultivated in different media and at different temperatures, and then screened for the production of antimicrobial activities. A total of 6348 extracts were prepared by solid phase extraction of the culture broths or by biomass solvent extraction. 122 bacteria showed antibacterial activity against the Gram-positives Staphylococcus aureus and to a lower extent Enterococcus faecium, and versus the Gram-negative Escherichia coli. Few of these strains showed also some antifungal activity against Cryptococcus neoformans, Aspergillus fumigatus and to a lower extent Candida albicans. LC–MS fractionation of extracts from a subset of strains (hits) that exhibited relatively potent antibacterial activities evidenced a chemical novelty that was further investigated. Two strains of Arthrobacter agilis produced potent antibacterial compounds with activity against Gram-positives and possibly related to novel cyclic thiazolyl peptides. To our knowledge, this is the first report of new antibiotics produced by bacteria from benthic microbial mats from Antarctic lakes. With no doubts these microbial assemblages represent an extremely rich source for the isolation of new strains producing novel bioactive metabolites with the potential to be developed as antibiotic compounds.     

Biogeochemical pools and fluxes of carbon and nitrogen in a maritime tundra near penguin colonies along the Antarctic Peninsula

There is limited information regarding biogeochemical pools and fluxes in maritime tundra ecosystems along the Antarctic Peninsula. To collect baseline information on biogeochemical processes in a tundra ecosystem dominated by two vascular plant species (Colobanthus quitensis and Deschampsia antarctica) at Biscoe Point off the coast of Anvers Island, we measured pools and fluxes of C and N in transplanted tundra microcosm cores, complemented with sampling of precipitation and surface runoff. Snow and snowmelt from the tundra collection site and soil leachates from the cores were enriched with N and dissolved organic carbon compared to precipitation and snowmelt samples collected at Palmer Station, indicating high loading of N and organic matter from the penguin colonies adjacent to the tundra site. Relatively high values of δ¹⁵N in the live and dead biomass of D. antarctica and C. quitensis (5.6–25.1‰) indicated an enrichment of N in this tundra ecosystem, possibly through N inputs from adjacent penguin colonies. Stepwise multiple linear regressions found that ecosystem respiration and gross primary production were best predicted by live biomass of D. antarctica, suggesting a disproportionately high contribution of D. antarctica to CO₂ fluxes. The cores with higher δ¹⁵N and lower δ¹³C in the soil organic horizon exhibited higher CO₂ fluxes. The results suggest that abundant N inputs from penguin colonies and the competitive balance between plant species might play a critical role in the response of tundra ecosystems along the Antarctic Peninsula to projected climate change.