Bibliographies : « Antarctic Metazoans »

1

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 et Tatyana V. Shendrik. « Eukarya biodiversity in the Thala Hills, East Antarctica ». Antarctic Science 33, n^o 6 (26 octobre 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 et 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 et 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 juillet 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 et Peter D. Nichols. « Horizontal patchiness in sympagic organisms of the Antarctic fast ice ». Antarctic Science 9, n^o 4 (décembre 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 et Ulker Akgul. « Metazoan Parasites of Antarctic Fishes ». Turkish Journal of Parasitology 39, n^o 2 (15 juin 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 et 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 (mai 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 et Jonathan S. Stark. « Environmental DNA metabarcoding for monitoring metazoan biodiversity in Antarctic nearshore ecosystems ». PeerJ 9 (15 novembre 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, et 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 janvier 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 et 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 (novembre 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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