Artigos de revistas: "Antarctic Metazoans"

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Lukashanets, Dzmitry A., Peter Convey, Oleg I. Borodin, Vladislav Ye Miamin, Yury H. Hihiniak, Alexey A. Gaydashov, Aleksander P. Yatsyna, Vasil V. Vezhnavets, Natallia N. Maysak e Tatyana V. Shendrik. "Eukarya biodiversity in the Thala Hills, East Antarctica". Antarctic Science 33, n.º 6 (26 de outubro de 2021): 605–23. http://dx.doi.org/10.1017/s0954102021000328.

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AbstractKnowledge of the biodiversity of the Thala Hills oasis (Enderby Land, East Antarctica) is very limited. Here, we integrate all information available since 1962, when the Russian ‘Molodyozhnaya’ station was established in the western part of the oasis. The published data on local eukaryote diversity (lichens, embryophytes, metazoans) include records of 90 species. Since 2008, Belarusian Antarctic Expedition researchers have worked in the eastern part of the oasis, accessible from the Belarusian station ‘Vechernyaya Mount'. This research revealed 95 species, including 44 species not recorded in the earlier published literature. The level of available information is uneven across major taxa. Lichens are the better-known group, with 51 species recorded in total, including 13 species recently recorded for the first time in the oasis. New records were also obtained for rotifers. Thala Hills biodiversity is consistent with wider patterns of Antarctic biogeography, with a high proportion of regionally endemic species (especially metazoans), the occurrence of both endemic and bipolar species of lichens and generally low numbers of cosmopolitan species (largely limited to aquatic rotifers, with the caveat that up-to-date taxonomic studies are required). The lack of data on marine macrobenthos, soil nematodes and terrestrial rotifers emphasizes the need for studies focusing on these groups.

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Vecchi, Matteo, Michele Cesari, Roberto Bertolani, K. Ingemar Jönsson, Lorena Rebecchi e Roberto Guidetti. "Corrigendum to: Integrative systematic studies on tardigrades from Antarctica identify new genera and new species within Macrobiotoidea and Echiniscoidea". Invertebrate Systematics 30, n.º 5 (2016): 521. http://dx.doi.org/10.1071/is15033_co.

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Tardigrades represent one of the most abundant groups of Antarctic metazoans in terms of abundance and diversity, thanks to their ability to withstand desiccation and freezing; however, their biodiversity is underestimated. Antarctic tardigrades from Dronning Maud Land and Victoria Land were analysed from a morphological point of view with light microscopy and scanning electron microscopy, and from a molecular point of view using two genes (18S, 28S) analysed in Bayesian inference and maximum-likelihood frameworks. In addition, indel-coding datasets were used for the first time to infer tardigrade phylogenies. We also compared Antarctic specimens with those from Italy and Greenland. A combined morphological and molecular analysis led to the identification of two new evolutionary lineages, for which we here erect the new genera Acanthechiniscus, gen. nov. (Echiniscidae, Echiniscoidea) and Mesobiotus, gen. nov. (Macrobiotidae, Macrobiotoidea). Moreover, two species new to science were discovered: Pseudechiniscus titianae, sp. nov. (Echiniscidae : Echiniscoidea) and Mesobiotus hilariae, sp. nov. (Macrobiotidae : Macrobiotoidea). This study highlights the high tardigrade diversity in Antarctica and the importance of an integrated approach in faunal and taxonomic studies.

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Vecchi, Matteo, Michele Cesari, Roberto Bertolani, K. Ingemar Jönsson, Lorena Rebecchi e Roberto Guidetti. "Integrative systematic studies on tardigrades from Antarctica identify new genera and new species within Macrobiotoidea and Echiniscoidea". Invertebrate Systematics 30, n.º 4 (2016): 303. http://dx.doi.org/10.1071/is15033.

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Tardigrades represent one of the most abundant groups of Antarctic metazoans in terms of abundance and diversity, thanks to their ability to withstand desiccation and freezing; however, their biodiversity is underestimated. Antarctic tardigrades from Dronning Maud Land and Victoria Land were analysed from a morphological point of view with light microscopy and scanning electron microscopy, and from a molecular point of view using two genes (18S, 28S) analysed in Bayesian inference and maximum-likelihood frameworks. In addition, indel-coding datasets were used for the first time to infer tardigrade phylogenies. We also compared Antarctic specimens with those from Italy and Greenland. A combined morphological and molecular analysis led to the identification of two new evolutionary lineages, for which we here erect the new genera Acanthechiniscus, gen. nov. (Echiniscidae, Echiniscoidea) and Mesobiotus, gen. nov. (Macrobiotidae, Macrobiotoidea). Moreover, two species new to science were discovered: Pseudechiniscus titianae, sp. nov. (Echiniscidae : Echiniscoidea) and Mesobiotus hilariae, sp. nov. (Macrobiotidae : Macrobiotoidea). This study highlights the high tardigrade diversity in Antarctica and the importance of an integrated approach in faunal and taxonomic studies. http://zoobank.org/urn:lsid:zoobank.org:pub:8AAB42BF-B781-4418-A385-DC80C18EC31D

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Laybourn-Parry, Johanna. "Survival mechanisms in Antarctic lakes". Philosophical Transactions of the Royal Society of London. Series B: Biological Sciences 357, n.º 1423 (29 de julho de 2002): 863–69. http://dx.doi.org/10.1098/rstb.2002.1075.

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In Antarctic lakes, organisms are confronted by continuous low temperatures as well as a poor light climate and nutrient limitation. Such extreme environments support truncated food webs with no fish, few metazoans and a dominance of microbial plankton. The key to success lies in entering the short Antarctic summer with actively growing populations. In many cases, the most successful organisms continue to function throughout the year. The few crustacean zooplankton remain active in the winter months, surviving on endogenous energy reserves and, in some cases, continuing development. Among the Protozoa, mixotrophy is an important nutritional strategy. In the extreme lakes of the McMurdo Dry Valleys, planktonic cryptophytes are forced to sustain a mixotrophic strategy and cannot survive by photosynthesis alone. The dependence on ingesting bacteria varies seasonally and with depth in the water column. In the Vestfold Hills, Pyramimonas , which dominates the plankton of some of the saline lakes, also resorts to mixotrophy, but does become entirely photosynthetic at mid–summer. Mixotrophic ciliates are also common and the entirely photosynthetic ciliate Mesodinium rubrum has a widespread distribution in the saline lakes of the Vestfold Hills, where it attains high concentrations. Bacteria continue to grow all year, showing cycles that appear to be related to the availability of dissolved organic carbon. In saline lakes, bacteria experience sub–zero temperatures for long periods of the year and have developed biochemical adaptations that include anti–freeze proteins, changes in the concentrations of polyunsaturated fatty acids in their membranes and suites of low–temperature enzymes.

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Swadling, Kerrie M., John A. E. Gibson, David A. Ritz e Peter D. Nichols. "Horizontal patchiness in sympagic organisms of the Antarctic fast ice". Antarctic Science 9, n.º 4 (dezembro de 1997): 399–406. http://dx.doi.org/10.1017/s0954102097000515.

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Patchiness in the horizontal distribution of sympagic organisms was studied at an Antarctic coastal site during autumn. A hierarchical sampling design (nested ANOVA) was used to assess variation in the biota on scales from metres to kilometres. Metazoan abundance, chlorophyll concentration and salinity were measured in 54 sea ice cores. The metazoan fauna was dominated by nauplii of the copepod Paralabidocera antarctica (6 × 104 to 4 × 105 m−2). Other copepods present included Stephos longipes, Oncaea curvata, Oithona similis, Ctenocalanus citer, and unidentified harpacticoid copepods. Chlorophyll a concentrations were generally much higher than values recorded at other sites at the same time of the year, reaching a maximum of 78 mg m−2. Metazoan abundances did not correlate strongly with chlorophyll or salinity. Significant variability in abundance of P. antarctica and O. similis, and chlorophyll concentration occurred at the scale of kilometres, whereas salinity and other metazoan abundances were not significantly variable at any of the scales examined. Considerable variation was evident at scales of less than one metre.

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Oguz, Mehmet Cemal, Yahya Tepe, Mark C. Belk, Richard A. Heckmann, Burcak Aslan, Meryem Gurgen, Rodney A. Bray e Ulker Akgul. "Metazoan Parasites of Antarctic Fishes". Turkish Journal of Parasitology 39, n.º 2 (15 de junho de 2015): 174–78. http://dx.doi.org/10.5152/tpd.2015.3661.

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Vanhove, S., H. J. Lee, M. Beghyn, D. Van Gansbeke, S. Brockington e M. Vincx. "The Metazoan Meiofauna in Its Biogeochemical Environment: The Case of an Antarctic Coastal Sediment". Journal of the Marine Biological Association of the United Kingdom 78, n.º 2 (maio de 1998): 411–34. http://dx.doi.org/10.1017/s0025315400041539.

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The metazoan meiobenthos was investigated in an Antarctic coastal sediment (Factory Cove, Signy Island, Antarctica). The fine sands contained much higher abundances compared to major sublittoral sediments worldwide. Classified second after Narrangansett Bay (North Atlantic) they reached numbers of 13 × 106ind m-2. The meiofauna was highly abundant in the surface layers, but densities decreased sharply below 2 cm. Vertical profiles mirrored steep gradients of microbiota, chloropigments and organic matter and were coincident with chemical stratification. Spatial patchiness manifested especially in the surface layer. Nematodes dominated (up to 90%), andAponema, Chromctdorita, Diplolaimella, Daptonema, MicrolaimusandNeochromadoraconstituted almost the entire community. Overall, the nematode fauna showed a strong similarity with fine sand communities elsewhere. The dominant trophic strategies were epistrarum and non-selective deposit feeding, but the applied classification for feeding guild structure of the nematodes of Factory Cove is discussed. High standing stock, low diversity and shallow depth distribution may have occurred because of the high nutritive (chlorophyll exceeded lOOOmgm-2and constituted almost 50% of the organic pool) and reductive character of the benthic environment. These observations must have originated from the substantial input of fresh organic matter from phytoplankton and microphytobenthic production, typical for an Antarctic coastal ecosystem during the austral summer.

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Clarke, Laurence J., Leonie Suter, Bruce E. Deagle, Andrea M. Polanowski, Aleks Terauds, Glenn J. Johnstone e Jonathan S. Stark. "Environmental DNA metabarcoding for monitoring metazoan biodiversity in Antarctic nearshore ecosystems". PeerJ 9 (15 de novembro de 2021): e12458. http://dx.doi.org/10.7717/peerj.12458.

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Antarctic benthic ecosystems support high biodiversity but their characterization is limited to a few well-studied areas, due to the extreme environment and remoteness making access and sampling difficult. Our aim was to compare water and sediment as sources of environmental DNA (eDNA) to better characterise Antarctic benthic communities and further develop practical approaches for DNA-based biodiversity assessment in remote environments. We used a cytochrome c oxidase subunit I (COI) metabarcoding approach to characterise metazoan communities in 26 nearshore sites across 12 locations in the Vestfold Hills (East Antarctica) based on DNA extracted from either sediment cores or filtered seawater. We detected a total of 99 metazoan species from 12 phyla across 26 sites, with similar numbers of species detected in sediment and water eDNA samples. However, significantly different communities were detected in the two sample types at sites where both were collected (i.e., where paired samples were available). For example, nematodes and echinoderms were more likely to be detected exclusively in sediment and water eDNA samples, respectively. eDNA from water and sediment core samples are complementary sample types, with epifauna more likely to be detected in water column samples and infauna in sediment. More reference DNA sequences are needed for infauna/meiofauna to increase the proportion of sequences and number of taxa that can be identified. Developing a better understanding of the temporal and spatial dynamics of eDNA at low temperatures would also aid interpretation of eDNA signals from polar environments. Our results provide a preliminary scan of benthic metazoan communities in the Vestfold Hills, with additional markers required to provide a comprehensive biodiversity survey. However, our study demonstrates the choice of sample type for eDNA studies of benthic ecosystems (sediment, water or both) needs to be carefully considered in light of the research or monitoring question of interest.

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Nezhybová, Veronika, e Šárka Mašová. "Basic epidemiological data on metazoan parasites of noto-thenioid fish off James Ross Island (Prince Gustav Channel, Weddell Sea), Antarctica". Czech Polar Reports 5, n.º 1 (1 de janeiro de 2015): 44–54. http://dx.doi.org/10.5817/cpr2015-1-5.

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During the Czech Antarctic expedition 2014, 102 fish of six species (Trematomus hansoni, T.bernacchii, T. newnesi, Notothenia coriiceps, Parachaenichthys charcoti, Pagothenia borchgrevinki) were examined for parasites. The fish were caught in the Prince Gustav Channel (depth about 5–25 m) off the Johann Gregor Mendel Station on the James Ross Island. Altogether 7,925 metazoan parasites were found, which were identified to individual groups (usually classes). The most abundant were nematode larvae (prevalence 97.0 %, mean abundance 32.7 larvae/per fish), followed by acanthocephalans, especially larvae of species of Corynosoma (76.5%, 14.9) and monogeneans (77.5%, 13.0). Cestodes (Diphyllobothriidea, Tetraphyllidea) were represented by larval stages whereas trematodes only by adults. Our preliminary data may help in future studies on fish parasites in Antarctica because they indicate the most abundant groups of parasites occurring in notothenioid fish.

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Stoecker, Diane K., Mary Putt e Tiffany Moisan. "Nano- and Microplankton Dynamics during the Spring Phaeocystis Sp. Bloom in McMurdo Sound, Antarctica". Journal of the Marine Biological Association of the United Kingdom 75, n.º 4 (novembro de 1995): 815–32. http://dx.doi.org/10.1017/s0025315400038170.

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The seasonal development of the microbial food web in eastern McMurdo Sound, Antarctica, was investigated during and immediately after the 1990–1991 bloom of Phaeocystis sp. (Prymnesiophyceae: Prymnesiales). From 23 November to 7 December, which was before the appearance of macroscopic colonies of Phaeocystis, both phytoplankton and Protozoa were low in abundance. During the Phaeocystis bloom (~10 December to 7 January), phytoplankton biomass was high and was dominated by colonial and singlecelled Phaeocystis, but other phytoplankton taxa, including diatoms and photosynthetic dinoflagellates, co-occurred. Heterotrophic nanoplankton and protozoan microzooplankton increased dramatically in biomass during the bloom. Non-thecate heterotrophic dinoflagellates were the most abundant microzooplankters. There was no evidence for inhibition of the microbial food web by Phaeocystis. By the post-bloom period, macroscopic colonies were rare and phytoplankton biomass had declined markedly. Microzooplankton biomass continued to rise until the end of the sampling period (23 January). Microfaecal pellets (median size range, 10–30 μm) were abundant during the bloom and post-bloom periods. In the post-bloom period, the heterotrophic protistan assemblage became very diverse, with numerous trophic linkages within the microbial food web. The abundance and diversity of the heterotrophic protist assemblage suggests that there was little control of protists by metazoans and that the microbial food web, consisting of bacteria, algae and Protozoa, was poorly coupled to metazoan zooplankton.

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Lipps, Jere H., e James W. Valentine. "Late Neoproterozoic Metazoa: Weird, Wonderful and Ghostly". Paleontological Society Papers 10 (novembro de 2004): 51–66. http://dx.doi.org/10.1017/s1089332600002333.

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The Late Neoproterozoic or Ediacaran biota contains a variety of enigmatic fossils of uncertain, but likely metazoan, affinities. The protistan group Choanoflagellata and Metazoa share a common ancestor predating the first fossils by perhaps 100's of millions of years. Sponge choanocytes closely resemble choanoflagellates, establishing a morphologic similarity as well. Fossils in the late Neoproterozoic may represent stem or early groups of cnidarians, while others resemble eumetazoans and bilaterians. These organisms occurred on all continents except Antarctica, and occupied four major habitats from prodeltaic to deep slope environments in each area. Their paleoecology was complex but similar to modern soft-bodied slope organisms. Ediacaran trophic structures were complex as well and included a wide variety of feeding types from detritovores, herbivores on microbial mats, filter-feeders, and predators. Ediacaran assemblages thus constitute the evolutionary and ecological precursors of later Phanerozoic and modern biotas.

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Barrett, J. E., R. A. Virginia, D. H. Wall, S. C. Cary, B. J. Adams, A. L. Hacker e J. M. Aislabie. "Co-variation in soil biodiversity and biogeochemistry in northern and southern Victoria Land, Antarctica". Antarctic Science 18, n.º 4 (14 de novembro de 2006): 535–48. http://dx.doi.org/10.1017/s0954102006000587.

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Data from six sites in Victoria Land (72–77°S) investigating co-variation in soil communities (microbial and invertebrate) with biogeochemical properties showthe influence of soil properties on habitat suitability varied among local landscapes as well as across climate gradients. Species richness of metazoan invertebrates (Nematoda, Tardigrada and Rotifera) was similar to previous descriptions in this region, though identification of three cryptic nematode species of Eudorylaimus through DNA analysis contributed to the understanding of controls over habitat preferences for individual species. Denaturing Gradient Gel Electrophoresis profiles revealed unexpectedly high diversity of bacteria. Distribution of distinct bacterial communities was associated with specific sites in northern and southern Victoria Land, as was the distribution of nematode and tardigrade species. Variation in soil metazoan communities was related to differences in soil organic matter, while bacterial diversity and community structure were not strongly correlated with any single soil property. There were no apparent correlations between metazoan and bacterial diversity, suggesting that controls over distribution and habitat suitability are different for bacterial and metazoan communities. Our results imply that top-down controls over bacterial diversity mediated by their metazoan consumers are not significant determinants of bacterial community structure and biomass in these ecosystems.

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Sohlenius, Björn, e Sven Boström. "The geographic distribution of metazoan microfauna on East Antarctic nunataks". Polar Biology 28, n.º 6 (28 de janeiro de 2005): 439–48. http://dx.doi.org/10.1007/s00300-004-0708-z.

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Kuhn, Thomas, Vera M. A. Zizka, Julian Münster, Regina Klapper, Simonetta Mattiucci, Judith Kochmann e Sven Klimpel. "Lighten up the dark: metazoan parasites as indicators for the ecology of Antarctic crocodile icefish (Channichthyidae) from the north-west Antarctic Peninsula". PeerJ 6 (11 de maio de 2018): e4638. http://dx.doi.org/10.7717/peerj.4638.

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Due to its remote and isolated location, Antarctica is home to a unique diversity of species. The harsh conditions have shaped a primarily highly adapted endemic fauna. This includes the notothenioid family Channichthyidae. Their exceptional physiological adaptations have made this family of icefish the focus of many studies. However, studies on their ecology, especially on their parasite fauna, are comparatively rare. Parasites, directly linked to the food chain, can function as biological indicators and provide valuable information on host ecology (e.g., trophic interactions) even in remote habitats with limited accessibility, such as the Southern Ocean. In the present study, channichthyid fish (Champsocephalus gunnari: n = 25, Chaenodraco wilsoni: n = 33, Neopagetopsis ionah: n = 3, Pagetopsis macropterus: n = 4, Pseudochaenichthys georgianus: n = 15) were collected off South Shetland Island, Elephant Island, and the tip of the Antarctic Peninsula (CCAML statistical subarea 48.1). The parasite fauna consisted of 14 genera and 15 species, belonging to the six taxonomic groups including Digenea (four species), Nematoda (four), Cestoda (two), Acanthocephala (one), Hirudinea (three), and Copepoda (one). The stomach contents were less diverse with only Crustacea (Euphausiacea, Amphipoda) recovered from all examined fishes. Overall, 15 new parasite-host records could be established, and possibly a undescribed genotype or even species might exist among the nematodes.

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Thatje, Sven, Alastair Brown e Claus-Dieter Hillenbrand. "Prospects for metazoan life in sub-glacial Antarctic lakes: the most extreme life on Earth?" International Journal of Astrobiology 18, n.º 05 (15 de janeiro de 2019): 416–19. http://dx.doi.org/10.1017/s1473550418000356.

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AbstractAbout 400 subglacial lakes are known from Antarctica. The question of whether life unique of subglacial lakes exists has been paramount since their discovery. Despite frequent evidence of microbial life mostly from accretion ice, subglacial lakes are characterized by physiologically hostile conditions to metazoan life, as we know it. Pure water (salinity ≤0.4–1.2%), extreme cold (−3°C), high hydrostatic pressure, areas of limited or no oxygen availability and permanent darkness altogether require physiological adaptations to these harsh conditions. The record of gene sequences including some associated with hydrothermal vents does foster the idea of metazoan life in Lake Vostok. Here, we synthesize the physico-chemical environment surrounding sub-glacial lakes and potential sites of hydrothermal activity and advocate that the physico-chemical stability found at these sites may be the most likely sites for metazoan life to exist. The unique conditions presented by Lake Vostok may also offer an outlook on life to be expected in extra-terrestrial subglacial environments, such as on Jupiter's moon Europa or Saturn's moon Enceladus.

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Kiko, R., I. Werner, S. Schnack-Schiel e M. Lucassen. "Antarctic sea ice: Habitat characteristics, metazoan fauna, and adaptations to low temperature". Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 146, n.º 4 (abril de 2007): S211—S212. http://dx.doi.org/10.1016/j.cbpa.2007.01.529.

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Gradinger, Rolf R. "Adaptation of Arctic and Antarctic ice metazoa to their habitat". Zoology 104, n.º 3-4 (janeiro de 2001): 339–45. http://dx.doi.org/10.1078/0944-2006-00039.

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González-Aravena, Marcelo, Nathan J. Kenny, Magdalena Osorio, Alejandro Font, Ana Riesgo e César A. Cárdenas. "Warm temperatures, cool sponges: the effect of increased temperatures on the Antarctic sponge Isodictya sp." PeerJ 7 (3 de dezembro de 2019): e8088. http://dx.doi.org/10.7717/peerj.8088.

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Although the cellular and molecular responses to exposure to relatively high temperatures (acute thermal stress or heat shock) have been studied previously, only sparse empirical evidence of how it affects cold-water species is available. As climate change becomes more pronounced in areas such as the Western Antarctic Peninsula, both long-term and occasional acute temperature rises will impact species found there, and it has become crucial to understand the capacity of these species to respond to such thermal stress. Here, we use the Antarctic sponge Isodictya sp. to investigate how sessile organisms (particularly Porifera) can adjust to acute short-term heat stress, by exposing this species to 3 and 5 °C for 4 h, corresponding to predicted temperatures under high-end 2080 IPCC-SRES scenarios. Assembling a de novo reference transcriptome (90,188 contigs, >93.7% metazoan BUSCO genes) we have begun to discern the molecular response employed by Isodictya to adjust to heat exposure. Our initial analyses suggest that TGF-β, ubiquitin and hedgehog cascades are involved, alongside other genes. However, the degree and type of response changed little from 3 to 5 °C in the time frame examined, suggesting that even moderate rises in temperature could cause stress at the limits of this organism’s capacity. Given the importance of sponges to Antarctic ecosystems, our findings are vital for discerning the consequences of short-term increases in Antarctic ocean temperature on these and other species.

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Jarman, Simon, Nicholas Elliott, Stephen Nicol, Andrew McMinn e Stuart Newman. "The base composition of the krill genome and its potential susceptibility to damage by UV-B". Antarctic Science 11, n.º 1 (março de 1999): 23–26. http://dx.doi.org/10.1017/s0954102099000048.

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We have determined the base composition (percentage of guanine-cytosine base pairs, GC%) of total DNA from Euphausia superba to be 32% ± 0.5%. This is the lowest GC% recorded for a metazoan. Low GC% DNA has high concentrations of thymine (T) residues and consequently a greater abundance of adjacent T residues [T(n) arrays]. Ultraviolet B (280–320 nm, UV-B) radiation damages DNA primarily at (T)n arrays, so we suggest that krill DNA may be more susceptible to damage from increased levels of UV-B radiation over the Southern Ocean than the DNA of other Antarctic organisms.

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Meier, Terje. "A checklist of Norwegian Tardigrada". Fauna norvegica 37 (20 de dezembro de 2017): 25–42. http://dx.doi.org/10.5324/fn.v37i0.2269.

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Animals of the phylum Tardigrada are microscopical metazoans that seldom exceed 1 mm in length. They are recorded from terrestrial, limnic and marine habitats and they have a distribution from Arctic to Antarctica. Tardigrades are also named ‘water bears’ referring to their ‘walk’ that resembles a bear’s gait. Knowledge of Norwegian tardigrades is fragmented and distributed across numerous sources. Here this information is gathered and validity of some records is discussed. In total 146 different species are recorded from the Norwegian mainland and Svalbard. Among these, 121 species and subspecies are recorded in previous publications and another 25 species are recorded from Norway for the first time.

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Kiko, R., I. Werner, S. Schnack-Schiel e M. Lucassen. "Antarctic sea ice: Habitat characteristics, metazoen fauna, and adaptations to low temperature". Comparative Biochemistry and Physiology Part A: Molecular & Integrative Physiology 146, n.º 4 (abril de 2007): S154. http://dx.doi.org/10.1016/j.cbpa.2007.01.314.

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Günther, Sven, Kai Horst George e Markus Gleitz. "High sympagic metazoan abundance in platelet layers at Drescher Inlet, Weddell Sea, Antarctica". Polar Biology 22, n.º 2 (23 de julho de 1999): 82–89. http://dx.doi.org/10.1007/s003000050393.

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Webster-Brown, J., M. Gall, J. Gibson, S. Wood e I. Hawes. "The biogeochemistry of meltwater habitats in the Darwin Glacier region (80°S), Victoria Land, Antarctica". Antarctic Science 22, n.º 6 (dezembro de 2010): 646–61. http://dx.doi.org/10.1017/s0954102010000787.

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AbstractMeltwater habitats in the Darwin Glacier region, Victoria Land (80°S), were sampled in December 2007 and January 2009 to characterize their microbial and metazoan ecology, nutrient status and geochemistry. Targeted areas included terrestrial ponds of the Grant Valley, Lake Wellman, Tentacle Ridge and Diamond Hill, and supraglacial ponds and cryoconite holes of the lower Darwin Glacier. Geochemistry ranged from Na-Cl dominated terrestrial ponds to Na-HCO3dominated, dilute supraglacial ponds and cryoconites. All showed the nitrate enrichment typical of inland ponds of Victoria Land (up to 13 g.l-1NO3-N), with some precipitating nitratine (NaNO3) salt. Elevated pH indicated ongoing photosynthetic processes. Benthic microbial mats were thin and poorly developed, dominated by oscillatoriacean cyanobacteria. Nitrogen-fixing genera were generally absent and diatoms were rare. A large (20 μm long)Cyanothecespecies was the most abundant cyanobacterium in the water and in sediments of the cryoconites. DNA finger-printing identified distinct differences in cyanobacterial and bacterial community structure between the cryoconites, terrestrial ponds and ponds on glacial margins. Eleven metazoan species were identified, with rotifers being the most abundant. Pond substrate (terrestrial rock, ice-cored moraine or supraglacial ice) proved to be a more significant influence on biogeochemistry than other aspects of geography or climatic conditions.

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Thurber, AR. "Diets of Antarctic sponges: links between the pelagic microbial loop and benthic metazoan food web". Marine Ecology Progress Series 351 (6 de dezembro de 2007): 77–89. http://dx.doi.org/10.3354/meps07122.

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Bowser, Samuel S., e Ted E. DeLaca. "“Skeletal” Elements Involved in Prey Capture by the Antrarctic Foraminiferan Astrammina Rara". Proceedings, annual meeting, Electron Microscopy Society of America 43 (agosto de 1985): 484–85. http://dx.doi.org/10.1017/s0424820100119247.

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Benthic foraminifera are considered primarily as “grazers” on bacteria, algae and other protozoans. However, in the benthic communities of the Ross Sea, Antarctica, field observations indicated that several species of agglutinated foraminifera (e.g., Astramina rara—shell ca. 2mm diameter) captured and digested larger metazoans (e.g., isopods such as Munna sp.—ca. 1cm in length). During prey capture the foraminiferan's reticulopodia (thin, anastomosing pseudopodia; Fig. 1) withstood the prey's vigorous escape efforts. We have attempted to identify the structural elements which impart the apparently high tensile strength of reticulopodia.To study the reticulopodial cytoskeleton, we fixed specimens of Astramina with 3% glutaraldehyde/0.1M PIPES supplemented with 0.04% tannic acid, followed by brief postfixation with 0.5% 0s04. The reticulopodial surface was examined in specimens fixed with 3% glutaraldehyde/0.1M PIPES supplemented with 1.5mg/ml ruthenium red, followed by 0.5% OsO4 containing 1.5mg/ml ruthenium red.

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Fransz, H. G., e S. R. Gonzalez. "Latitudinal metazoan plankton zones in the antarctic circumpolar current along 6°W during austral spring 1992". Deep Sea Research Part II: Topical Studies in Oceanography 44, n.º 1-2 (janeiro de 1997): 395–414. http://dx.doi.org/10.1016/s0967-0645(96)00065-3.

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Woulds, Clare, James B. Bell, Adrian G. Glover, Steven Bouillon e Louise S. Brown. "Benthic carbon fixation and cycling in diffuse hydrothermal and background sediments in the Bransfield Strait, Antarctica". Biogeosciences 17, n.º 1 (2 de janeiro de 2020): 1–12. http://dx.doi.org/10.5194/bg-17-1-2020.

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Abstract. Sedimented hydrothermal vents are likely to be widespread compared to hard substrate hot vents. They host chemosynthetic microbial communities which fix inorganic carbon (C) at the seafloor, as well as a wide range of macroinfauna, including vent-obligate and background non-vent taxa. There are no previous direct observations of carbon cycling at a sedimented hydrothermal vent. We conducted 13C isotope tracing experiments at three sedimented sites in the Bransfield Strait, Antarctica, which showed different degrees of hydrothermalism. Two experimental treatments were applied, with 13C added as either algal detritus (photosynthetic C), or as bicarbonate (substrate for benthic C fixation). Algal 13C was taken up by both bacteria and metazoan macrofaunal, but its dominant fate was respiration, as observed at deeper and more food-limited sites elsewhere. Rates of 13C uptake and respiration suggested that the diffuse hydrothermal site was not the hot spot of benthic C cycling that we hypothesised it would be. Fixation of inorganic C into bacterial biomass was observed at all sites, and was measurable at two out of three sites. At all sites, newly fixed C was transferred to metazoan macrofauna. Fixation rates were relatively low compared with similar experiments elsewhere; thus, C fixed at the seafloor was a minor C source for the benthic ecosystem. However, as the greatest amount of benthic C fixation occurred at the “Off Vent” (non-hydrothermal) site (0.077±0.034 mg C m−2 fixed during 60 h), we suggest that benthic fixation of inorganic C is more widespread than previously thought, and warrants further study.

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Rivkin, RB, e TE DeLaca. "Trophic dynamics in antarctic benthic communities. I. In situ ingestion of microalgae by Foraminifera and metazoan meiofauna". Marine Ecology Progress Series 64 (1990): 129–36. http://dx.doi.org/10.3354/meps064129.

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Bell, James B., Alfred Aquilina, Clare Woulds, Adrian G. Glover, Crispin T. S. Little, William D. K. Reid, Laura E. Hepburn, Jason Newton e Rachel A. Mills. "Geochemistry, faunal composition and trophic structure in reducing sediments on the southwest South Georgia margin". Royal Society Open Science 3, n.º 9 (setembro de 2016): 160284. http://dx.doi.org/10.1098/rsos.160284.

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Despite a number of studies in areas of focused methane seepage, the extent of transitional sediments of more diffuse methane seepage, and their influence upon biological communities is poorly understood. We investigated an area of reducing sediments with elevated levels of methane on the South Georgia margin around 250 m depth and report data from a series of geochemical and biological analyses. Here, the geochemical signatures were consistent with weak methane seepage and the role of sub-surface methane consumption was clearly very important, preventing gas emissions into bottom waters. As a result, the contribution of methane-derived carbon to the microbial and metazoan food webs was very limited, although sulfur isotopic signatures indicated a wider range of dietary contributions than was apparent from carbon isotope ratios. Macrofaunal assemblages had high dominance and were indicative of reducing sediments, with many taxa common to other similar environments and no seep-endemic fauna, indicating transitional assemblages. Also similar to other cold seep areas, there were samples of authigenic carbonate, but rather than occurring as pavements or sedimentary concretions, these carbonates were restricted to patches on the shells of Axinulus antarcticus (Bivalvia, Thyasiridae), which is suggestive of microbe–metazoan interactions.

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Petz, Wolfgang. "Ecology of the active soil microfauna (Protozoa, Metazoa) of Wilkes Land, East Antarctica". Polar Biology 18, n.º 1 (3 de junho de 1997): 33–44. http://dx.doi.org/10.1007/s003000050156.

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Belcher, Anna, Sophie Fielding, Andrew Gray, Lauren Biermann, Gabriele Stowasser, Peter Fretwell, Louise Ireland e Geraint A. Tarling. "Experimental determination of reflectance spectra of Antarctic krill (Euphausia superba) in the Scotia Sea". Antarctic Science 33, n.º 4 (12 de julho de 2021): 402–14. http://dx.doi.org/10.1017/s0954102021000262.

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AbstractAntarctic krill are the dominant metazoan in the Southern Ocean in terms of biomass; however, their wide and patchy distribution means that estimates of their biomass are still uncertain. Most currently employed methods do not sample the upper surface layers, yet historical records indicate that large surface swarms can change the water colour. Ocean colour satellites are able to measure the surface ocean synoptically and should theoretically provide a means for detecting and measuring surface krill swarms. Before we can assess the feasibility of remote detection, more must be known about the reflectance spectra of krill. Here, we measure the reflectance spectral signature of Antarctic krill collected in situ from the Scotia Sea and compare it to that of in situ water. Using a spectroradiometer, we measure a strong absorption feature between 500 and 550 nm, which corresponds to the pigment astaxanthin, and high reflectance in the 600–700 nm range due to the krill's red colouration. We find that the spectra of seawater containing krill is significantly different from seawater only. We conclude that it is tractable to detect high-density swarms of krill remotely using platforms such as optical satellites and unmanned aerial vehicles, and further steps to carry out ground-truthing campaigns are now warranted.

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Olivero, Eduardo B., e Maria I. López Cabrera. "EuflabellaN. Igen.: Complex Horizontal Spreite Burrows in Upper Cretaceous–Paleogene Shallow-Marine Sandstones of Antarctica and Tierra del Fuego". Journal of Paleontology 87, n.º 3 (maio de 2013): 413–26. http://dx.doi.org/10.1666/12-088.1.

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Fine-grained sandstones and siltstones of Late Cretaceous to Eocene age in Antarctica and Tierra del Fuego yield an association of well-known shallow-marine trace fossils. Among them stick out complex spreite burrows, which are formally described asEuflabellan. igen. and subdivided into five ichnospecies with different burrowing programs and occurrences. As shown by concentrations of diatoms, radiolarians, foraminifers, and calcispheres in particular backfill lamellae, the unknown trace makers lived on fresh detritus from the surface as well as the burrowed sediment. In some ichnospecies, vertical sections show that the spreite is three-dimensionally meandering in upward direction and that upper laminae tend to rework the upper backfill of the folds underneath. This could mean a second harvest, after cultivated bacteria had time to ferment refractory sediment components, which the metazoan trace maker had been unable to digest before.

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Lane, Steven J., Caitlin M. Shishido, Amy L. Moran, Bret W. Tobalske, Claudia P. Arango e H. Arthur Woods. "Upper limits to body size imposed by respiratory–structural trade-offs in Antarctic pycnogonids". Proceedings of the Royal Society B: Biological Sciences 284, n.º 1865 (25 de outubro de 2017): 20171779. http://dx.doi.org/10.1098/rspb.2017.1779.

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Across metazoa, surfaces for respiratory gas exchange are diverse, and the size of those surfaces scales with body size. In vertebrates with lungs and gills, surface area and thickness of the respiratory barrier set upper limits to rates of metabolism. Conversely, some organisms and life stages rely on cutaneous respiration, where the respiratory surface (skin, cuticle, eggshell) serves two primary functions: gas exchange and structural support. The surface must be thin and porous enough to transport gases but strong enough to withstand external forces. Here, we measured the scaling of surface area and cuticle thickness in Antarctic pycnogonids, a group that relies on cutaneous respiration. Surface area and cuticle thickness scaled isometrically, which may reflect the dual roles of cuticle in gas exchange and structural support. Unlike in vertebrates, the combined scaling of these variables did not match the scaling of metabolism. To resolve this mismatch, larger pycnogonids maintain steeper oxygen gradients and higher effective diffusion coefficients of oxygen in the cuticle. Interactions among scaling components lead to hard upper limits in body size, which pycnogonids could evade only with some other evolutionary innovation in how they exchange gases.

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Signor, Philip W. "Taxonomic diversity and faunal turnover in the Early Cambrian: Did the most severe mass extinction of the Phanerozoic occur in the Botomian stage?" Paleontological Society Special Publications 6 (1992): 272. http://dx.doi.org/10.1017/s2475262200008327.

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A handful of mass extinctions, scattered through the Phanerozoic, forever changed the course of life on Earth, eliminating large numbers of clades from the evolutionary race and allowing the survivors to diversify following the extinction. These ecological-evolutionary upheavals extirpated whole communities and eliminated otherwise successful clades from the evolutionary race. While the mechanism(s) responsible for most mass extinctions remain to be identified, their impact on the biosphere is self-evident. Thus, recognition of a previously overlooked, severe extinction early in the Phanerozoic provides important new insights and perspectives on the history of lifeIn the course of research on the biogeographic distribution of Early Cambrian metazoan taxa, I compiled a database on the geographic and stratigraphic distribution of metazoan genera. The data are derived from the primary literature on the paleogeographic and stratigraphic distributions and systematics of Early Cambrian fossils. The Russian zonation scheme for the Siberian Platform (incorporating four stages, in ascending order: Tommotian, Atabanian, Botomian, and Toyonian) was employed for biostratigraphic correlations. Correlations of other regions to the Siberian stages were based upon work by F. Debrenne and her colleagues on archaeocyathans and upon M. D. Brasier's correlations from small shelly fossils. While there is no accepted global correlation scheme for Lower Cambrian strata, this approach yields results that are useful at the four-stage level of resolution. The data base currently includes more than 850 genera.Examination of the aggregate data reveals a substantial reduction (>60%) in the global total of genera extant in the Toyonian, in comparison to the Botomian stage. The extinction rate of genera at the end of the Botomian exceeds 80 percent. By comparison, the end-Permian extinction eliminated slightly more than 60 percent of the extant genera.In addition to the general reduction in generic diversity, Brasier (1982) has documented a fall in sea level and reduction in the shelf area. Associated with this regression was a loss of reef-forming archaeocyathan genera. While a small number of archaeocyathan genera persisted into the Toyonian (and a few genera have been reported from Late Cambrian strata in Antarctica), the bulk of archaeocyath diversity was lost in the Botomian. The losses in diversity, extermination of reef-forming organisms, and high turnover in conjunction with a marine regression matches the pattern observed at most other mass extinctions.It is remarkable that this relatively severe extinction has gone mostly unnoticed by paleobiologists. Much of the data is relatively new, a product of intense international study of early metazoan faunas. Most likely, the mass of data produced by Lower Cambrian specialists over the past ten years has yet to reach the treatises and monographs where it can be easily summarized. Also, resolution of patterns within the Early Cambrian has waited on the development of correlations and a satisfactory zonation. Indeed, detailed study of the Botomian extinction will await more accurate correlations.

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Hoshijima, Umihiko, Juliet M. Wong e Gretchen E. Hofmann. "Additive effects of pCO2 and temperature on respiration rates of the Antarctic pteropod Limacina helicina antarctica". Conservation Physiology 5, n.º 1 (2017). http://dx.doi.org/10.1093/conphys/cox064.

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Abstract The Antarctic pteropod, Limacina helicina antarctica, is a dominant member of the zooplankton in the Ross Sea and supports the vast diversity of marine megafauna that designates this region as an internationally protected area. Here, we observed the response of respiration rate to abiotic stressors associated with global change—environmentally relevant temperature treatments (−0.8°C, 4°C) and pH treatments reflecting current-day and future modeled extremes (8.2, 7.95 and 7.7 pH at −0.8°C; 8.11, 7.95 and 7.7 pH at 4°C). Sampling repeatedly over a 14-day period in laboratory experiments and using microplate respirometry techniques, we found that the metabolic rate of juvenile pteropods increased in response to low-pH exposure (pH 7.7) at −0.8°C, a near-ambient temperature. Similarly, metabolic rate increased when pteropods were exposed simultaneously to multiple stressors: lowered pH conditions (pH 7.7) and a high temperature (4°C). Overall, the results showed that pCO2 and temperature interact additively to affect metabolic rates in pteropods. Furthermore, we found that L. h. antarctica can tolerate acute exposure to temperatures far beyond its maximal habitat temperature. Overall, L. h. antarctica appears to be susceptible to pH and temperature stress, two abiotic stressors which are expected to be especially deleterious for ectothermic marine metazoans in polar seas.

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Damm, Elena, Kristian K. Ullrich, William B. Amos e Linda Odenthal-Hesse. "Evolution of the recombination regulator PRDM9 in minke whales". BMC Genomics 23, n.º 1 (16 de março de 2022). http://dx.doi.org/10.1186/s12864-022-08305-1.

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Abstract Background PRDM9 is a key regulator of meiotic recombination in most metazoans, responsible for reshuffling parental genomes. During meiosis, the PRDM9 protein recognizes and binds specific target motifs via its array of C2H2 zinc-fingers encoded by a rapidly evolving minisatellite. The gene coding for PRDM9 is the only speciation gene identified in vertebrates to date and shows high variation, particularly in the DNA-recognizing positions of the zinc-finger array, within and between species. Across all vertebrate genomes studied for PRDM9 evolution, only one genome lacks variability between repeat types – that of the North Pacific minke whale. This study aims to understand the evolution and diversity of Prdm9 in minke whales, which display the most unusual genome reference allele of Prdm9 so far discovered in mammals. Results Minke whales possess all the features characteristic of PRDM9-directed recombination, including complete KRAB, SSXRD and SET domains and a rapidly evolving array of C2H2-type-Zincfingers (ZnF) with evidence of rapid evolution, particularly at DNA-recognizing positions that evolve under positive diversifying selection. Seventeen novel PRDM9 variants were identified within the Antarctic minke whale species, plus a single distinct PRDM9 variant in Common minke whales – shared across North Atlantic and North Pacific minke whale subspecies boundaries. Conclusion The PRDM9 ZnF array evolves rapidly, in minke whales, with at least one DNA-recognizing position under positive selection. Extensive PRDM9 diversity is observed, particularly in the Antarctic in minke whales. Common minke whales shared a specific Prdm9 allele across subspecies boundaries, suggesting incomplete speciation by the mechanisms associated with PRDM9 hybrid sterility.

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Fonseca, V. G., A. Kirse, H. Giebner, B. J. Vause, T. Drago, D. M. Power, L. S. Peck e M. S. Clark. "Metabarcoding the Antarctic Peninsula biodiversity using a multi-gene approach". ISME Communications 2, n.º 1 (13 de abril de 2022). http://dx.doi.org/10.1038/s43705-022-00118-3.

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AbstractMarine sediment communities are major contributors to biogeochemical cycling and benthic ecosystem functioning, but they are poorly described, particularly in remote regions such as Antarctica. We analysed patterns and drivers of diversity in metazoan and prokaryotic benthic communities of the Antarctic Peninsula with metabarcoding approaches. Our results show that the combined use of mitochondrial Cox1, and 16S and 18S rRNA gene regions recovered more phyla, from metazoan to non-metazoan groups, and allowed correlation of possible interactions between kingdoms. This higher level of detection revealed dominance by the arthropods and not nematodes in the Antarctic benthos and further eukaryotic diversity was dominated by benthic protists: the world’s largest reservoir of marine diversity. The bacterial family Woeseiaceae was described for the first time in Antarctic sediments. Almost 50% of bacteria and 70% metazoan taxa were unique to each sampled site (high alpha diversity) and harboured unique features for local adaptation (niche-driven). The main abiotic drivers measured, shaping community structure were sediment organic matter, water content and mud. Biotic factors included the nematodes and the highly abundant bacterial fraction, placing protists as a possible bridge for between kingdom interactions. Meiofauna are proposed as sentinels for identifying anthropogenic-induced changes in Antarctic marine sediments.

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Lukashanets, Dzmitry A., Yury H. Hihiniak e Vladislav Y. Miamin. "Extremely high abundances of Prasiola crispa-associated micrometazoans in East Antarctica". Polar Research 41 (20 de junho de 2022). http://dx.doi.org/10.33265/polar.v41.7781.

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To elucidate poorly known aspects of the microscopic metazoan distribution in ice-free parts of the Antarctic, we examined samples of the multicellular terrestrial alga Prasiola crispa, collected over the last decade in different parts of continental East Antarctica and Haswell Island. We found that the micrometazoans inhabiting the algae consist of remarkably abundant bdelloid rotifers (subclass Bdelloidea), followed by tardigrades. We did not find nematodes. The rotifer assemblages were characterized by low diversity (only six species). Nevertheless, rotifer densities were extremely high: mean densities ranged from 75 to 3030 individuals per 100 mg of the dry sample weight and the maximum value numbered in excess of 8000 per 100 mg of the dry sample weight. These data show that terrestrial algae, along with mosses, are a very attractive habitat for rotifers and tardigrades in the Antarctic. The statistical analysis showed a lack of correlations between rotifer and tardigrade densities and nutrients (N, C, P, K and Na). Our findings are consistent with the patchy distribution of terrestrial micrometazoans in the Antarctic that has previously been found.

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Johnston, Nadine M., Eugene J. Murphy, Angus Atkinson, Andrew J. Constable, Cédric Cotté, Martin Cox, Kendra L. Daly et al. "Status, Change, and Futures of Zooplankton in the Southern Ocean". Frontiers in Ecology and Evolution 9 (17 de junho de 2022). http://dx.doi.org/10.3389/fevo.2021.624692.

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In the Southern Ocean, several zooplankton taxonomic groups, euphausiids, copepods, salps and pteropods, are notable because of their biomass and abundance and their roles in maintaining food webs and ecosystem structure and function, including the provision of globally important ecosystem services. These groups are consumers of microbes, primary and secondary producers, and are prey for fishes, cephalopods, seabirds, and marine mammals. In providing the link between microbes, primary production, and higher trophic levels these taxa influence energy flows, biological production and biomass, biogeochemical cycles, carbon flux and food web interactions thereby modulating the structure and functioning of ecosystems. Additionally, Antarctic krill (Euphausia superba) and various fish species are harvested by international fisheries. Global and local drivers of change are expected to affect the dynamics of key zooplankton species, which may have potentially profound and wide-ranging implications for Southern Ocean ecosystems and the services they provide. Here we assess the current understanding of the dominant metazoan zooplankton within the Southern Ocean, including Antarctic krill and other key euphausiid, copepod, salp and pteropod species. We provide a systematic overview of observed and potential future responses of these taxa to a changing Southern Ocean and the functional relationships by which drivers may impact them. To support future ecosystem assessments and conservation and management strategies, we also identify priorities for Southern Ocean zooplankton research.

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Voronina, N. M., K. N. Kosobokova e E. A. Pakhomov. "Composition and biomass of summer metazoan plankton in the 0?200 m layer of the Atlantic sector of the Antarctic". Polar Biology 14, n.º 2 (fevereiro de 1994). http://dx.doi.org/10.1007/bf00234970.

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Müller, Svenja J., Katharina Michael, Ilenia Urso, Gabriele Sales, Cristiano De Pittà, Lavinia Suberg, Wiebke Wessels, Evgeny A. Pakhomov e Bettina Meyer. "Seasonal and Form-Specific Gene Expression Signatures Uncover Different Generational Strategies of the Pelagic Tunicate Salpa thompsoni During the Southern Ocean Winter". Frontiers in Marine Science 9 (16 de junho de 2022). http://dx.doi.org/10.3389/fmars.2022.914095.

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The pelagic tunicate Salpa thompsoni is recognized as a major metazoan grazer in the Southern Ocean. Long term observations show an increase in this species’ biomass and a southward shift in its distribution both of which are positively correlated with ocean warming and winter sea ice decline around the Antarctic Peninsula. However, our understanding on how salps adapt their life cycle to the extreme seasonality of the Southern Ocean and the putative differences between its two reproductive forms (aggregates, solitaries) is rudimentary. In particular, our current knowledge of whether and how S. thompsoni overwinter is limited, largely due to winter sampling constraints. In this study, we investigated the form-specific gene expression profiles of Salpa thompsoni during the austral autumn and winter. Between the seasons, genes related to translation showed the biggest difference in gene expression. We found more genes were upregulated in solitaries compared to aggregates, indicating a potentially form-specific overwintering strategy. Our data provide first insights into the seasonal and form-specific physiology of salps by considering their complex life cycle, thereby contributing to a more comprehensive understanding of the response of salps to seasonal changes in their environment and to anthropogenic induced global climate change.

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Zawierucha, Krzysztof, Craig J. Marshall, David Wharton e Karel Janko. "A nematode in the mist: Scottnema lindsayae is the only soil metazoan in remote Antarctic deserts, at greater densities with altitude". Polar Research 38 (7 de maio de 2019). http://dx.doi.org/10.33265/polar.v38.3494.

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