The anatomical characters related to the brooding behavior of two Antarctic species of <Emphasis Type="Italic">Mysella</Emphasis> Angas, 1877 (Bivalvia,Galeommatoidea, Lasaeidae), with direct and indirect evidences of ovoviviparity

Brood protection is a common feature of marine bivalves from higher latitudes. In this study the pallial organs of the Antarctic bivalves, Mysella charcoti (Lamy, 1906) and M. narchii Passos & Domaneschi, 2006 were investigated with respect to anatomical characters related to brooding. Both species are simultaneous hermaphrodites and their eggs contain a large amount of yolk. The number of broods ranges from 16 to 30 in M. narchii and 7–27 in M. charcoti, and ovoviviparity was observed for both. Their ctenidia differ in structure, those of M. charcoti being simpler. In M. narchii there is a large elasticity of the tissue of the marginal food grooves of ctenidia, and cilia are much more abundant on the ctenidial abfrontal surface and on the visceral mass epithelium than in M. charcoti. Anatomical characters of M. charcoti can be considered derived when compared to those of M. narchii. In conclusion, detailed anatomical characters related to brooding may be useful in future systematic studies of Antarctic Bivalvia.     

Scanning electron microscope evidence for diatom uptake by two Antarctic sponges

Scanning electron microscopy (SEM) investigation of two Antarctic sponges, Phorbas glaberrima and Tedania charcoti, showed that the exopinacoderm effects a direct uptake of benthic diatoms which settle on the sponge surface. In P. glaberrima, planktonic diatoms were also observed penetrating through the inhalant system, the primary way of feeding in sponges. Benthic diatoms which accumulate in the mesohyl underneath the exopinacoderm help to strengthen the sponge cortex and may be an alimentary source during oligotrophic periods in the Antarctic environment.     

Occurrence of the flea Glaciopsyllus antarcticus and avian lice in central Dronning Maud Land

The flea Glaciopsyllus antarcticus is endemic to the Antarctic continent, where it is known to parasitise a number of seabird species. This paper reports the occurrence of the flea and two species of lice from snow petrel (Pagodroma nivea) colonies in central Dronning Maud Land, Antarctica, and extends considerably the recorded distribution of the flea. Flea adults, pupae and larvae were recovered from 10 of 11 samples of organic material collected from snow petrel nests at Svarthamaren (71°53^′S, 05°10^′E) in the Mühlig-Hofmannfjella. Specimens of two philopterid lice species, Saemundssonia antarctica and Pseudonirmus charcoti, were recovered from three of these samples. Specimens of the Antarctic flea and of the louse S. antarctica were recovered from carcasses of snow petrel chicks collected both at Svarthamaren and Robertskollen (71°28^′S, 03°15^′W) in the northern Ahlmannryggen; the louse Pseudonirmus charcoti was recovered from Robertskollen only. Received: 30 January 1996 / Accepted: 28 April 1997     

Biology and functional morphology of the pallial organs of the Antarctic bivalve Mysella charcoti (Lamy, 1906) (Galeommatoidea: Lasaeidae)

Mysella charcoti is an Antarctic lasaeid bivalve and the most frequently encountered mollusc in Admiralty Bay, King George Island, South Shetlands. The behaviour of the species in aquaria, combined with analyses of the gross and microscopic morphologies and functioning of the organs in the mantle cavity of living and preserved specimens have allowed an understanding of important aspects of its biology. The role of the foot and its ciliature during the processes of dislodgement and burrowing within the sediment are described. The species is a free-living, shallow-burrower, with a predominantly deposit-feeding habit and derives part of its food from the labile settled organic deposits carried into the mantle cavity by the anterior–posterior current of water. Pedal sweep-feeding was not detected. M. charcoti is the first known lasaeid with ctenidia formed of the descending lamellae of the inner demibranchs only, a feature probably related to its highly specialised brooding habit.     

A new species of Mysella Angas, 1877 (Bivalvia: Galeommatoidea) from Admiralty Bay, King George Island, South Shetlands, Antarctica, with data on its biology and functional anatomy

Mysella narchii sp. nov. is described from the material collected in shallow-waters of Admiralty Bay at King George Island, South Shetlands, Antarctica. The species is characterized by shell features, biology and functional anatomy. The main shell features distinguishing M. narchii sp. nov. from all other Antarctic, Subantarctic and Magellanic Mysella spp. are provided, as are anatomical characteristics that separate this new species from M. charcoti (Lamy, 1906), its most similar congener and the first Antarctic species studied in its morpho-functional aspects. M. narchii sp. nov. is an infaunal, free-living, predominantly deposit-feeding bivalve; its creeping sole and the secretion of byssal threads allow it to crawl vertically and live sporadically on firm substrata.     

Age and growth of the Antarctic dragonfish Parachaenichthys charcoti (Pisces, Bathydraconidae) from the southern Scotia Arc

The Antarctic dragonfish Parachaenichthys charcoti is commonly found in shelf waters of islands in the southern Scotia Arc. Its northern congener P. georgianus is distributed on the shelves of South Georgia and the South Sandwich Islands. Biological information on P. charcoti is limited and restricted largely to reproductive traits and feeding habits. The present study fills this gap, providing the first data on age and growth of this species by otolith reading. Age was estimated in juveniles and adults by counting annuli on otoliths. Age of early juveniles was determined by microincrement counts (considered to be daily rings). Age estimates of juveniles and adults ranged from 1 to 9?years, with a high percentage agreement between readings and low values of counting variability indices APE (3.3?%) and CV (4.7?%). Age of early juveniles ranged from 160 to 204?days, all showing an evident check at 32–35?days of age, tentatively linked to the first larval exogenous feeding. The estimated values of von Bertalanffy growth parameters L _∞ and k were 53.55?cm and 0.22, respectively, and the index of growth performance P was 2.33. Hatching in P. charcoti takes place in late winter, from August to September. Compared to other notothenioids inhabiting the Seasonal Pack-ice Zone, P. charcoti is a relatively fast growing species with moderate longevity, sharing several biological characteristics with its sister species P. georgianus.     

A panel of microsatellite loci from two species of octopus, Pareledone turqueti (Joubin, 1905) and Pareledone charcoti (Joubin, 1905)

Eighteen dinucleotide microsatellite loci were isolated from two octopus species, Pareledone turqueti and Pareledone charcoti, which are endemic to the Southern Ocean. Genetic diversity was assessed in samples of P. charcoti and P. turqueti from Elephant Island and Shag Rocks respectively. All except one locus (which has proved to be polymorphic in other species) were variable in the focal species and amplified between six and 30 and between four and 28 alleles for P. charcoti and P. turqueti respectively; mean expected heterozygosities varied between 0.38 and 0.95 (P. charcoti) and between 0.34 and 0.97 (P. turqueti), with significant (P < 0.05) departures from Hardy–Weinberg equilibrium at seven loci; three of these loci provided significant (P < 0.05) evidence for null alleles. Two pairs of loci isolated from P. turqueti demonstrated significant (P < 0.05) linkage disequilibrium. We are presently using these genetic markers to quantify spatial genetic structure in the genus Pareledone.     

New perspectives on the dispersal mechanisms of the Antarctic brooding bivalve Mysella charcoti (Lamy, 1906)

. Brooding is a widespread phenomenon among Antarctic bivalves. Although it should represent a handicap to dispersion, many brooding species have achieved a wide distribution in Antarctic and subantarctic waters, suggesting that they have alternative and effective methods of dispersal. Evidence of such an alternative method is presented here for the bivalve Mysella charcoti, unexpectedly found alive and healthy in feces expelled by Notothenia coriiceps (Nototheniidae: Pisces). The finding indicates that the snug-fitting shell of Mysella functions as a barrier to digestive enzymes. Withstanding passage through the digestive tract of fish allows Mysella to be passively dispersed (within the home range of the fish) and colonize new habitats or re-colonize shallow-water substrates severely impacted by ice scours.     

Closely related octopus species show different spatial genetic structures in response to the Antarctic seascape

Determining whether comparable processes drive genetic divergence among marine species is relevant to molecular ecologists and managers alike. Sympatric species with similar life histories might be expected to show comparable patterns of genetic differentiation and a consistent influence of environmental factors in shaping divergence. We used microsatellite loci to quantify genetic differentiation across the Scotia Arc in three species of closely related benthic octopods, Pareledone turqueti, P. charcoti, and Adelieledone polymorpha. The relative importance of environmental factors (latitude, longitude, depth, and temperature) in shaping genetic structure was investigated when significant spatial genetic structure was uncovered. Isolated populations of P. turqueti and A. polymorpha at these species’ range margins were genetically different to samples close to mainland Antarctica; however, these species showed different genetic structures at a regional scale. Samples of P. turqueti from the Antarctic Peninsula, Elephant Island, and Signy Island were genetically different, and this divergence was associated primarily with sample collection depth. By contrast, weak or nonsignificant spatial genetic structure was evident across the Antarctic Peninsula, Elephant Island, and Signy Island region for A. polymorpha, and slight associations between population divergence and temperature or depth (and/or longitude) were detected. Pareledone charcoti has a limited geographic range, but exhibited no genetic differentiation between samples from a small region of the Scotia Arc (Elephant Island and the Antarctic Peninsula). Thus, closely related species with similar life history strategies can display contrasting patterns of genetic differentiation depending on spatial scale; moreover, depth may drive genetic divergence in Southern Ocean benthos.     

Morphology,egg cocoons,and transmission paths of the Antarctic leech Glyptonotobdella antarctica Sawyer and White, 1969 (Hirudinea: Rhynchobdelliformes: Piscicolidae)

The biology of piscicolids which move between different host species is poorly understood. Very little is known about leeches of Antarctic waters, though they are not uncommon in that region. This paper adds to the fundamental knowledge of the Antarctic piscicolid leech Glyptonotobdella antarctica Sawyer and White, 1969. According to the new findings the distribution of the species has to be extended to the geographical latitude of 76°08.1′S and to a depth of 665 m. Besides Glyptonotus antarcticus Eights 1853, sea urchins of the genus Sterechinus (Meissner 1900), and the benthic octopus Pareledone (charcoti?) (Joubin 1905) serve as hosts. Hitherto there were only two records on piscicolids from Octopus dofleini and none from sea urchins. Egg cocoons on the ventral side of the isopod Glyptonotus antarcticus were attributed to the leech. Most likely Glyptonotobdella antarctica moves between different hosts, i.e. Antarctic octopuses and their potential prey. Surface structures of the leech are studied by light and scanning electron microscope. The observations complement the basic knowledge on Antarctic leeches and provide arguments for phylogenetic discussions.     

The influence of ice scour on benthic communities at three contrasting sites at Adelaide Island,Antarctica

Abstract Ice scouring is a key structuring force acting on high latitude shallow benthic communities. Despite its importance, detailed studies of scoured communities are still rare. Here we report the ecological effects of 12 iceberg impacts, across three contrasting study sites, at Adelaide Island, West Antarctic Peninsula. Grounded icebergs were marked with GPS and the newly formed scours (at 10–17 m depth) were sampled within 20 days of formation. Comparisons between scoured and adjacent unscoured assemblages were made using measures of abundance, biomass, taxon richness and the relative abundance of secondary consumers. Ice scouring was catastrophic at all sites, despite differences in substratum type, exposure and background community. Compared with undisturbed areas, scour assemblages were 95% lower in mean macrofaunal abundance and 75.9% lower in species richness. There was no general trend across all sites of ice scouring selecting for secondary consumers. The echinoid Sterechinus neumayeri and bivalve mollusc Mysella charcoti were highly abundant in undisturbed areas and were the biggest contributors to the observed differences between scours and undisturbed areas.     

Demersal fish parasite fauna around the South Shetland Islands: high species richness and low host specificity in deep Antarctic waters

A total of nine Antarctic fish species belonging to five families were examined for their endohelminth parasite fauna. The fishes Parachaenichthys charcoti (Bathydraconidae), Chaenocephalus aceratus (Channichtyidae), Paradiplospinus gracilis (Gempylidae), Muraenolepis microps (Muraenolepididae), Gobionotothen gibberifrons, Lepidonotothen larseni, L. nudifrons, L. squamifrons, and Trematomus eulepidopus (Nototheniidae) were caught between 80 and 608 m trawling depth off the Antarctic Peninsula (Elephant Island, King George Island) in 1996. Nineteen different parasites species comprising five Digenea, two Cestoda, four Nematoda, and eight Acanthocephala were found. Pseudophyllidean cestodes, the nematodes Contracaecum radiatum and C. osculatum as well as the acanthocephalan Corynosoma bullosum were the most common, infesting eight of the fish species studied with prevalences reaching 100%. Pseudoterranova decipiens s.l. was the only parasite that was isolated from all studied fish species; however, at a lower intensity. The observed parasite host specificity was low, and the species richness in a single fish ranged from one to eleven in a C. aceratus. This icefish and the moray cod M. microps were the most heavily infested fish, harbouring many adult and larval parasitic stages. The benthodemersal P. gracilis had only two larval parasite species, while the nototheniids had very similar parasite communities, harbouring a total of 8–14 species. Larval mammalian parasites were found to utilize fish, especially the nototheniids and channichthyids, as a common transmission route into their final hosts. The fish parasites parallel explored different benthic host systems to reach the most suitable host. In contrast to the coast and continental shelf, the meso/bathypelagiac zone appears to be species poor and is inhabited by few larval forms. The fish parasite fauna off the South Shetland Islands can be characterized by generalistic parasites that distribute within Antarctic waters according to the feeding ecology and depth range of their teleost hosts, not only horizontally but also extending vertically into the deep sea.     

A further contribution on the biology of the Antarctic flea,Glaciopsyllus antarcticus (Siphonaptera: Ceratophyllidae)

Summary Experiments showed that adult Antarctic Fleas Gladopsyllus antarcticus preferred dark over light conditions, dry over wet conditions, and fine substrate over coarse substrate. Examination of seabird chicks and collections of nest material indicated that the Southern Fulmar Fulmarus glacialoides, is the major host species of the Antarctic Flea, while Snow Petrels Pagodroma nivea, Cape Petrels Daption capense, Antarctic Petrels Thalassoica antarctica, and Wilson's Storm-Petrels Oceanites oceanicus are minor hosts. This is the first report of Antarctic Fleas occuring on either Antarctic Petrels or Wilson's Storm-Petrels. No fleas were found associated with Southern Giant Petrels Macronectes giganteus, Antarctic Skuas Catharacta maccormicki, or Adelie Penguins Pygoscelis adeliae. No live fleas were found in Southern Fulmar nest material during their period of dispersal over the winter months, supporting the hypothesis that Antarctic Fleas survive the winter period by remaining on their seabird host.     

The genus Stauroneis (Bacillariophyceae) in the Antarctic region

Aim To provide a detailed biogeography of the diatom genus Stauroneis in the Antarctic and sub‐Antarctic regions and to establish the biogeographical relationships between the different constituent locations to test the application of a precise and refined taxonomy in generating accurate polar biogeographies. Location The Antarctic and sub‐Antarctic region comprising the islands South Georgia, Crozet, Kerguelen, Marion, Heard and the Antarctic Peninsula. Methods Diatom samples from different habitats in a large part of the sub‐Antarctic and Antarctic region were investigated for their Stauroneis content. Presence/absence data were investigated using Sørensen's similarity index. An additional 500 samples from Arctic locations were used to provide a bipolar comparison. Using reliable literature data, gaps in the distribution of the Stauroneis taxa were filled. Results The Stauroneis flora of the Antarctic and sub‐Antarctic regions is quite distinct from its Arctic equivalent, with only five species (out of 60) common to both areas. Within the (sub‐)Antarctic group, the islands of the Indian Ocean have the most diverse Stauroneis composition, which is clearly separated from the rest of the region. The South Georgia Stauroneis composition has some affinities with the Antarctic Peninsula but the latter has far fewer species. These results are in clear contrast to older data showing no biogeographical difference between the Arctic and Antarctic regions. Main conclusions Using only a single genus, a clear biogeography of the (sub‐)Antarctic region can be produced that separates the Indian Ocean islands from other sampling locations. When based on a precise taxonomy, biogeographical relationships between locations in the region become much more reliable. Contrary to previous work, there is almost no similarity in the diatom floras of the Arctic and Antarctic regions.     

The lichen genus Stereocaulon in Antarctica and South Georgia

Summary Six species of Stereocaulon and one unnamed taxon (close to S. glabrum) are reported from South Georgia, the maritime Antarctic islands and Antarctic Peninsula. S. caespitosum is new to the western sub-Antarctic. Variations in morphology and secondary chemistry are provided, and the ecology and geographical distribution in the sub-Antarctic and Antarctic biomes are given for each taxon.     

Filling biodiversity gaps: benthic hydroids from the Bellingshausen Sea (Antarctica)

The Bellingshausen Sea constitutes the third largest sea in the Southern Ocean, though it is widely recognized as one of the less-studied Antarctic areas. To reduce this lack of knowledge, a survey to study the biodiversity of its marine benthic communities was carried out during the Bentart 2003 and Bentart 2006 Spanish Antarctic expeditions. The study of the hydroid collection has provided 27 species, belonging to ten families and 15 genera. Twenty-one out of the 27 species constitute new records for the Bellingshausen Sea, raising the total number of known species to 37, as also do nine out of the 15 genera. Candelabrum penola, Lafoea annulata, and Staurotheca juncea are recorded for the second time. Most species belong to Leptothecata. Sertulariidae with 13 species (48%) is by far the most speciose family, and Symplectoscyphus with seven species (26%), including S. bellingshauseni sp. nov. and S. hesperides sp. nov., the most diverse genus. Considering the whole benthic hydroid fauna of the Bellingshausen Sea, 18 species (69%) are endemic to Antarctic waters, either with a circum-Antarctic (12 species, 46%) or West Antarctic (6 species, 23%) distribution, 23 (88%) are restricted to Antarctic or Antarctic/sub-Antarctic waters, and only three species have a wider distribution. Bellingshausen Sea hydroid fauna is composed of a relatively high diversity of typical representatives of the Antarctic benthic hydroid fauna, though with a surprisingly low representation of some of the most diverse and widespread Antarctic genera (Oswaldella and Schizotricha), what could be related to the fact that its shelf-inhabiting hydroid fauna remains practically unknown.     

Benthic hydroids (Cnidaria: Hydrozoa) from the Bransfield Strait area (Antarctica) collected by Brazilian expeditions,with the description of a new species

A total of 36 species of benthic hydroids, belonging to nine families and 16 genera, were found in the hydroid collection gathered during the Brazilian Antarctic expeditions PROANTAR III and IV. Seven of the species were identified only to generic level. There is a clear dominance of the subclass Leptothecatae with 33 species. By far the most diversified family was the Sertulariidae, with 16 species (44%). Symplectoscyphus with eight species, including Symplectoscyphus magnificus sp. nov., is the most diversified genus. Almost 70% of the species diversity is restricted to just six genera (38%). Sixty-eight percent of the species is Antarctic endemics and 86% is restricted to Antarctic or Antarctic/sub-Antarctic waters. Eudendrium antarcticum and Amphisbetia operculata are recorded for the first time from Antarctic waters.     

Prevalence of <Emphasis Type="Italic">Edwardsiella tarda</Emphasis> in Antarctic wildlife

For many years, the Antarctic region has been isolated from human activity. However, there is little data available regarding endemic and exotic diseases. The purpose of this work was to determine the prevalence of Edwardsiella tarda in Antarctic wildlife, including birds, mammals and fish. During the summer of 2000 and 2002 in the Potter Peninsula, and during the summer of 2001 and 2003 in Hope Bay, a total of 1,805 faecal samples from Antarctic animals and 50 infertile eggs of Adelie penguins (Pygoscelis adeliae) were collected in order to isolate E. tarda. The classic Edwardsiella tarda was isolated from 281 (15.1%) of the 1,855 Antarctic wildlife samples. This is the first report of E. tarda isolation from southern giant petrels (Macronectes giganteus), brown skuas (Stercorarius lonnbergi), south polar skuas (Stercorarius maccormicki), kelp gulls (Larus dominicanus), greater sheathbills (Chionis albus), chinstrap penguins (Pygoscelis antarctica), eggs of Adelie penguins and Weddell seals (Leptonychotes weddelli). None of the evaluated animals showed clinical signs of disease. Our results suggest that E. tarda is a common bacterium amongst Antarctic birds and mammals.     

On the use of high‐throughput sequencing for the study of cyanobacterial diversity in Antarctic aquatic mats

The study of Antarctic cyanobacterial diversity has been mostly limited to morphological identification and traditional molecular techniques. High‐throughput sequencing (HTS) allows a much better understanding of microbial distribution in the environment, but its application is hampered by several methodological and analytical challenges. In this work, we explored the use of HTS as a tool for the study of cyanobacterial diversity in Antarctic aquatic mats. Our results highlight the importance of using artificial communities to validate the parameters of the bioinformatics procedure used to analyze natural communities, since pipeline‐dependent biases had a strong effect on the observed community structures. Analysis of microbial mats from five Antarctic lakes and an aquatic biofilm from the Sub‐Antarctic showed that HTS is a valuable tool for the assessment of cyanobacterial diversity. The majority of the operational taxonomic units retrieved were related to filamentous taxa such as Leptolyngbya and Phormidium, which are common genera in Antarctic lacustrine microbial mats. However, other phylotypes related to different taxa such as Geitlerinema, Pseudanabaena, Synechococcus, Chamaesiphon, Calothrix, and Coleodesmium were also found. Results revealed a much higher diversity than what had been reported using traditional methods and also highlighted remarkable differences between the cyanobacterial communities of the studied lakes. The aquatic biofilm from the Sub‐Antarctic had a distinct cyanobacterial community from the Antarctic lakes, which in turn displayed a salinity‐dependent community structure at the phylotype level.     

The lichen genus <Emphasis Type="Italic">Umbilicaria</Emphasis> from the neighbourhood of Admiralty Bay (King George Island,maritime Antarctic), with a proposed new key to all Antarctic taxa

This paper documents the occurrence of the genus Umbilicaria in the neighbourhood of Admiralty Bay on King George Island in the maritime Antarctic. Nine species are reported from the area surveyed, with Umbilicaria kappeni being reported from King George Island for the first time. The occurrence of U. aprina, U. cristata and U. umbilicarioides on the island is confirmed and that of U. aprina is its first documented record from the maritime Antarctic. Fertile specimens of U. umbilicarioides are recorded for the first time from Antarctica. The area around Admiralty Bay seems to be one of the Antarctic regions with the highest diversity of Umbilicaria species. The diagnostic characters and distribution of each species are discussed. An updated key for identification of all the Antarctic species of the genus is provided.