Now showing items 21-40 of 191

    • Recent Naticidae (Mollusca: Gastropoda) from the Patagonian coast

      Pastorino, G. (2005)
      The Veliger
      This is the first comprehensive revision of the gastropod family Naticidae from the Patagonian coast. The valid species are redescribed, based on type and other specimens, and illustrated, including SEM photographs of radulae and jaws. This revision is based on specimens collected at localities ranging from Uruguay and northern Argentina southwards to Tierra del Fuego, the Straits of Magellan, the Beagle Channel and the Malvinas Islands, along with some material from South Georgia, South Shetland, the South Orkney Islands, and the Palmer (Antarctic) Peninsula. Only thirteen of the numerous nominal species described from the Patagonian coast are herein considered valid: Notocochlis isabellean (d'Orbigny, 1840); ''Natica'' limbata d'Orbigny, 1837; Tectonatica impervia (Philippi, 1845); Euspira con-stricta Dall, 1891; E. strebeli Dall, 1891; E. patagonica (Philippi, 1845); E. falklandica (Preston, 1913); Falsilunatia soluta (Gould, 1847); Bulbus carcellesi Dell, 1990; Polinices sp. cf. P. uber (Valenciennes, 1832); ''Amauropsis'' anderssoni (Strebel, 1906); ''A.'' aureolutea (Strebel, 1908) and Kerguelenatica bioperculata Dell, 1990. In order to resolve the identity of several species, lectotypes were selected for the following species: Natica isabelleana d'Orbigny, 1840; N. limbata d'Orbigny, 1837; and a neotype of Falsilunatia soluta (Gould, 1847) is herein designated.
    • Polychaete Assemblages in South Western Atlantic : Results of “ Shinkai Maru ” Iv , V , X and Xi ( 1978- 1979 ) Cruises in Patagonia and Buenos Aires .

      Bremec, C.; Souto, V.; Genzano, G. (2010)
      Anales Instituto Patagonia, Chile
      The aim of this paper is to study the polychaete composition from a wide area in the Argentinean shelf, between 36°S and 55°S, by means of samples collected from soft bottoms with Picard dredge, during the "Shinkai Maru" cruises developed in 1978-79. As the study area comprises both the Magellanic and Argentinean Biogeographic Provinces, we analyze if these results show differences in polychaete composition between both Provinces. A total of 816 individuals was studied; 29 families, represented by 70 taxa, were identified. The most frequent (36-57% sampling stations) and abundant families were Onuphidae, Nephtyidae and Ampharetidae, mainly represented by Kinbergonuphis dorsalis, Aglaopha-mus sp. and Ampharete kerguelensis, respectively. Cluster Analysis, SIMPER test and ANOSIM showed two different species assemblages in two well defined areas according to a nearly 60m depth boundary, in correspondence with the classical Magellanic and Argentinean Provinces.
    • On the southerly extent of the Antarctic Circumpolar the southeast Pacific

      Read, J.; Pollard, R.; Morrison, A.; Symon, C. (1995)
      Deep Sea Research Part II: Topical Studies in Oceanography
      A front at 67°S in the Bellingshausen Sea at 85°W is shown to be part of the Antarctic Circumpolar Current (ACC) and the southernmost zone of concentrated eastward transport at that longitude. The front lies 6° south of the Polar Front at 88°W and 3° north of the Continental Water Boundary. The front is continuous to the east through Drake Passage where it forms a southern branch of the Polar Front, for which reason we have named it the Southern Polar Front. Data from a towed profiling CTD were able to distinguish the Polar Front from the Southern Polar Front, even though they were only 0.5° apart. Thus the width of the ACC south of the Polar Front varied considerably. About a third of the transport of the ACC also lay south of the Polar Front, with 15 Sv carried by the Southern Polar Front alone at 85°W. Distinguishing features of the Southern Polar Front were a water mass boundary associated with a zone of concentrated baroclinic flow and a surface salinity minimum. These features also have been found at the Greenwich Meridian at 53°S, so the Southern Polar Front can be traced round at least a quarter of the globe. To the west of the Bellingshausen Sea both Eltanin data and the Fine Resolution Antarctic Model show that the AAC is at its narrowest at 145°W, where its southern boundaries lie as far north as 56°S. At this longitude the ACC meets the topographic barrier of the Pacific-Antarctic Ridge. To conserve potential vorticity the current is forced to make a southward loop as it crosses the ridge and the current broadens dramatically. The flow remains broad until forced to sharpen by the constriction of Drake Passage. A similar broadening of the ACC is seen where it crosses the Southwest Indian Ridge south of Africa at 30°E. Here it remains broad until it encounters the Kerguelen Plateau. Thus the eastern boundaries of both the Weddell and Ross Gyres are determined by where the ACC crosses midocean ridges.
    • Occurrence of orange roughy, Hoplostethus atlanticus (Trachichthyidae) off Argentina

      Wöhler, O.; Scarlato, N. (2006)
      Cybium: international journal of ichthyology
      Présence de l’hoplostète orange, Hoplostethus atlanti-cus(Trachichthyidae), en Argentine.
    • Observations on Cumacea (Malacostraca: Peracarida) from Antarctic and subantarctic waters. I. Ekleptostylis debroyeri (Diastylidae), a new species from waters off the Antarctic Peninsula

      Blazewicz-Paszkowycz, M.; Heard, R. (2001)
      Proceedings of the Biological Society of Washington
      Eighteen species of diastylid cumaceans have been described from Antarctic and subantarctic waters. A nineteenth species, Ekleptostylis debroyeri, n. sp., was collected in depths of 83 to 530 m off the Antarctic Peninsula. The new species appears to be closely allied to Ekleptostylis heardi McLelland & Meyer, 1998; E. inornata (Hale, 1937), n. comb.; E. pseudoinornata (Ledoyer, 1977); and E. vemae (Bǎcescu-Mester, 1967), all of which are known from subantarctic and Antarctic waters. Ekleptostylis debroyeri is distinguished from these species by a combination of characters including the size of the anterior-most pair of lateral spiniform setae of the telson and the proximal article of the uropodal endopod subequal to the combined length of the two distal most articles. The genera Diastylis Say, 1818, Ekleptostylis Stebbing, 1912, and Leptostylis G.O. Sars, 1869 have morphological features that appear to be transitional, especially among the subadults and females. The generic status of many species within these genera can only be determined with certainty by the morphology (length of antenna, structure of the second pereopod, ornamentation of telson) of the terminal male stage. Although the mature male of E. debroyeri is unknown, it is tentatively placed in Ekleptostylis based on the similarity of the female to other known species of the genus.
    • Observations o parasitism by Thalassomyces fagei on three euphausiid species in Southern Atlantic waters

      Ramírez, F.; Dato, C. (1989)
      Oceanologica Acta
      The inhibiting effects of the parasite Thalassomycesfagei (Ellobiopsidae, Dinophyceae) on gonadic development in euphausiids have already been reported by several authors. Such castrative action reaches significant proportions in these crustaceans, which are important components in the diet of many commercially exploited fishes. In the present work, 2641 furciliae, post-larvae and adults of Euphausia lucens, E. vallentini and Thysanoessagregaria were examined. The samples were taken in Southern Atlantic waters by RjV "Walther Herwing" and "Shinkai Maru" between May 1978 and February 1979. Increasing incidence of parasitism was found at the end of winter and beginning of spring, the most commonly affected species being E. vallentini (9.9% of the total). Some reduction of secondary sexual characters was typically associated, though its extent was not constant
    • New species of Psolus Oken from Antarctica (Echinodermata: Holothuroidea: Psolidae)

      O'Loughlin, P.; Whitfield, E. (2010)
      Zootaxa
      Three new species of Psolus Oken from Antarctica are described: Psolus byrdae sp. nov. from the Marie Byrd Seamount; Psolus carolineae sp. nov. from South Georgia; Psolus lockhartae sp. nov. from the South Orkney Islands.
    • Los briozoos colectados por el B/I Shinkai Maru en la plataforma Continental Argentina.

      López-Gappa, J.; Lichtschein, V. (1990)
      Servicio de Hidrografia Naval
    • Infestation of Atlantic chaetognaths with helminths and ciliates

      Jarling, C.; Kapp, H. (1985)
      DISEASES OF AQUATIC ORGANISMS
      The parasite fauna of chaetognaths was investigated at 3 locations: (i) Patagonian Shelf, (ii) 'Great Meteor Bank', (iii) upwelling region off north-west Africa. On the Patagonian Shelf, 4 out of 3,000 chaetognaths (0.16%) were infested by Contracaecum-type larvae, 1 chaetognath harboured an Ectenurus sp. metacercaria. On the 'Great Meteor Bank', 18 out of 8,600 chaetognaths (0.2196) were infested by Cercaria owreae, Ectenurus lepidus, hemiuroid metacercariae or ciliates in April, whereas only 1 E. lepidus metacercaria was found in 4,400 chaetognaths (0.02%) in July. In the north-west African upwelling-region, 640 out of 20,000 chaetognaths (3.2%) were infested mainly by metacer-cariae of E. lepidus and by hemiuroid metacercariae, larval cestodes or ciliates. The distribution of E. lepidus in this area is outlined. The lengths of E. lepidusmetacercariae from north-west African waters increase significantly with distance from the coast. E. lepidus metacercariae were found predominantly in the tail coelom of the chaetognaths.
    • Infection variability of the parasitic copepod Eubrachiella antarctica (Quidor, 1906) on fishes in the Atlantic sector of the Antarctic

      Sosinski, J.; Janusz, J. (2000)
      Bulletin of the Sea Fisheries Institute
      Eubrachiella antarctica (Quidor, 1906) is the most commonly occurring ectoparasite in different fish species in the Atlantic sector of the Antarctic. The present work summarises re- sults of studies carried out by various authors from 1975 to 1988 and is devoted to the prevalence, intensity and distribution of parasites on 12 species of fishes. The results of the authors? own studies carried out during the cruise of R/V PROFESOR SIEDLECKI in the 1978/79 season were used to statistically evaluate the significance of differences of infection parameters of the studied fish species sampled at five locations. It was demonstrated that the parasite invasion level on some fish species varied significantly depending on the areas where the fishes were caught, which suggests the possible existence of distinct stocks of some fish species
    • II.—Spongiaires recueillis par la “Scotia” dans l'Antarctique (1903–1904)

      Topsent, E. (2016)
      Transactions of the Royal Society of Edinburgh
      Depuis la publication de mon mémoire sur les Spongiaires de V Expedition antarctique nationale écossaise (9), j'ai reçu de M. le Dr. W. S. Bruce quelques Eponges antarctiques faisant aussi partie des collections de la Scotia mais dont le triage s'était trouve retardé. Indépendamment de fragments en double d'espèces mentionées dans mon mémoire, ce second lot contenait plusieurs formes qu'il me paraît utile de signaler ou de décrire.
    • Hydroids from the Theta, Vema and Yelcho cruises of the Lamont-Doherty geological observatory

      Vervoort, W. (1972)
      Zoologische Verhandelingen
      The material reported upon below was received in 1968 from the America n Museum of Natural History, New York, U.S.A., and constisted of 124 lot s of unidentified hydroids, the majority of which originated from the con -tinental shelf bordering the Atlantic coasts of the American continent. A ver y significant part of the collection comprises material from localities alon g the Atlantic coast of southern Argentina, the Estrecho de Magellanes an d Tierra del Fuego, an area of great zoogeographical interest and with a badl y known though richly developed hydroid fauna. The hydroid material in th e present collection in many instances consisted of small fragments or had bee n badly compressed, so that a fairly high percentage Gould not properly b e identified. The localities, with some exceptions, are widely spaced, rangin g from the deep sea to a few metres depth. I do not feel justified, therefore , to draw more than a few very tentative zoogeographical conclusions, expectin g that the extension of the distributional range of certain species recorde d below can later on be used when a more complete survey of the hydroi d fauna of the southern part of South America is undertaken, preferabl y including material from more Pacific localities than at present I have a t my disposal .
    • Historia y perspectivas de los estudios sobre poliquetos en Argentina

      Elias, R.; Jaubet, M.; Ferrando, A.; Saracho Bottero, M. (2017)
      Boletín del Instituto Oceanográfico de Venezuela
      Se abordan diferentes temáticas relacionadas a la historia sobre los estudios de poliquetos en Argentina. Se analiza la evolución histórica de los estudios sobre estos anélidos, así como los investigadores que iniciaron y promovieron los primeros estudios sobre poliquetos recolectados en la Argentina. Luego, se brinda una perspectiva de los poliquetos en el marco de los estudios ecológicos. Se describen las especies registradas en playas arenosas y en la plataforma continental frente a Argentina. Otras temáticas abordadas fueron: 1) los poliquetos de agua dulce; 2)Los ensambles de poliquetos en respuesta a la contaminación orgánica; 3)El poliqueto invasor Boccardia proboscidea(Spionidae) en Argentina; 4)Los estudios biogeográficos; 5) Estudios taxonómicos y de diversidad local. Situación actual y situación futura.Si bien las investigaciones sobre una temática tan específica como los poliquetos nunca han sido particularmente impulsadas, algunos proyectos sobre taxonomía y ecología han sido financiados por entidades nacionales. Existe en la actualidad una iniciativa estratégica en el área de la investigación científica del mar, denominada "Pampa Azul". El objetivo de este proyecto es profundizar el conocimiento científico para fundamentar las prácticas de conservación y manejo de recursos renovables.
    • Gravity measurements over Burdwood Bank

      Davey, F. (1972)
      Marine Geophysical Researches
      Gravity measurements in the South Atlantic Ocean over Burdwood Bank show a large negative gravity anomaly extending along its northern edge. An interpretation of the gravity data has been made based on the seismic refraction measurements of Ludwig et al. (1968) and shows that the negative gravity anomaly can be largely attributed to a basin containing low density sediments about 8 km thick. The crustal sections constructed also indicate that the crust increases in thickness from about 20 km under Burdwood Bank to about 30 km under the Falkland Islands platform.
    • Geographie distribution of bryozoans in the Argentine Sea ( South-Western Atlantic )

      Lopez Gappa, J.; Lichstchein de Bastida, V. (1988)
      Oceanologica Acta
      On the basis of benthos dredgings carried out by the R. V. Shinkai Maru on the Argentine continental shelf, the bryozoan associations and their areas of distribution were analysed. Presence/absence data of 95 species at 58 stations were processed using correspondence analysis. The area analysis confirms the classical zoogeographie scheme proposed by varions authors for our coasts: a Magellanic group occupying most of the studied area and another composed of stations from the Argentine biogeographie province, occupying the inner shelf off Buenos Aires and north Pata-gonian gulfs. According to our results, the limit between both assemblages is situated near the coast at approximately 43°S and offshore, at depths of 60-72 rn following a SW-NE direction. A graduai and progressive impoverishment in species number towards the north and towards inner sectors of the shelf is observed off Chubut and Buenos Aires. The transitional zone between both zoogeographie provinces is inhabited by species of wide distribution, adapted to support the fluctuating hydrolo-gical conditions that characterize this area. Even though the results of this study have shown a higher number of species in the Magellanic group, a comparison between the Magellanic and Argentine provinces cannot yet be made, since the Uruguayan and south Brazilian bryozoan fauna, also included in the latter, is mostly unknown.
    • Frecuencia de estudio y diversidad de los hidrozoos bentónicos de la plataforma continental Argentina

      Genzano, G.; Zamponi, M. (1995)
      Ciencias Marinas
      Hyperlipidaemia is a pivotal risk factor for the development of atherosclerotic disease. A large number of studies have demonstrated that the treatment of abnormalities in lipoprotein levels reduces the risk for myocardial infarction, peripheral vascular disease, carotid artery disease, stroke, and cardiovascular mortality. Despite the development of multiple drug classes to treat dyslipidaemias and the promulgation of clearly defined guidelines for the management of lipid disorders, dyslipidaemia tends to be undertreated in the majority of patients at risk for cardiovascular disease. A part of the reluctance to treat different lipoprotein fractions to goal levels is attributable to physician- and patient-related concerns over the increasing toxicity of available therapies, as their dosages are increased. The risks of hepatotoxicity, myalgia, and rhabdomyolysis are fairly well characterised in patients receiving statins, fibrates and niacin. Another issue affecting treatment success rates is the fact that many patients with complex dyslipidaemias are inadequately responsive to single-agent therapy. As the epidemics of obesity, metabolic syndrome and diabetes mellitus continue to worsen, physicians will encounter severe, mixed dyslipidaemias more frequently. Many of these patients will require combinations of drugs to address the various metabolic derangements causing changes in multiple lipoprotein fractions. Although the need for combination therapy is well-established in the management of disorders, such as hypertension and diabetes, it is less often used for the treatment of dyslipidaemias. The development of safe, cost-effective, and efficacious combination dyslipidaemic therapy is an important goal in cardiovascular medicine. Simvastatin plus ezetimibe has recently been combined as a fixed dose therapy, which offers clinicians the opportunity to simultaneously inhibit two key pathways in cholesterol metabolism: hepatic cholesterol biosynthesis and the absorption of cholesterol at the level of the proximal jejunum. This dual mechanism of inhibition substantially increases the capacity to decrease serum levels of atherogenic low-density lipoproteins and increase high-density lipoprotein, compared with that observed when either drug is used alone. This combination increases the likelihood of therapeutic success in patients with dyslipidaemia
    • Four new species and a new genus of Antarctic sea cucumbers with taxonomic reviews of Cladodactyla, Pseudocnus, paracucumidae and Parathyonidium (Echinodermata: Holothuroidea: Dendrochirotida)

      O’Loughlin, P.; Mackenzie, M.; Paulay, G.; VandenSpiegel, D. (2014)
      Memoirs of Museum Victoria
      Four new species of Antarctic sea cucumbers are described, three with author O’Loughlin: Crucella susannae, Euthyonidiella huwi, Laevocnus katrinae; and Laevocnus leachmani with authors Davey and O’Loughlin. Pseudocnus Panning is reviewed, and Antarctic species separated into new genus Laevocnus O’Loughlin. We raise the three subspecies of Pseudocnus dubiosus, viz. dubiosus (Semper), koellikeri (Semper) and leoninus (Semper), to species status. We refer Cucumaria croceoida Vaney to the synonymy of Cladodactyla crocea (Lesson). We synonymize Dendrelasia O’Loughlin with Cladodactyla Brandt, and re-describe the reassigned Cladodactyla sicinski (O’Loughlin). This species broods in a dorsal marsupium. The diagnoses of genus Parathyonidium Heding and species Parathyonidum incertum Heding are reviewed. The type specimens for Parathyonidium incertum are listed. Parathyonidium incertum Heding is the only known Antarctic holothuroid that is a coelomic brooder. The Paracucumidae Pawson and Fell is reviewed. Phylogenetic trees are given for species in the genera Cladodactyla, Heterocucumis, Staurocucumis, Laevocnus, Crucella and Paracucumis. Tables are provided for the species of Cladodactyla and Pseudocnus. Keys are included for the species of genus Laevocnus and family Paracucumidae.
    • Foraminifera; Part 1 The ice-free area of the Falkland Islands and adjacent seas.

      Heron-allen, E.; Earland, A. (1932)
      Discovery Reports, Cambridge
      THEbottomdepositsreceivedfromtheR.R.S.'Discovery'andtheR.R.S. 'William coresby'coveraverywidearea.Apartfromgatheringsmadeenroute,whichare too widelyscatteredtoyieldmuchinformationexceptasregardsnewspecies contained therein,someofwhichhavebeenalreadydescribedbyusintheJournalofthe Royal MicroscopicalSociety,^theyincludedetailedsurveysoftheseabottom in ' (i)theseassurroundingtheFalkland Islands, (2)theSouthGeorgia area, (3)theSouthSandwich,theSouthOrkneys,theSouthShetlandsandoff the coastoftheAntarctic Continent. TheFalklandIslands,beingentirelyoutsidetheregionofice,formadefinite area andconstitutethesubjectofthepresent report.
    • Expedition ANTARKTIS XIX/5 (LAMPOS) of RV "Polarstern" in 2002

      Arntz, W.; Brey, T. (2003)
      Berichte Polarforsch.
      Special relationships exist between the waters around the southern part of South America, the Magellan Province, and the waters around the Subantarctic islands and the Antarctic continent. They have their origin in the common past of these regions as part of the Gondwana continent and in their close vicinity up to the present day as compared to the distances between Antarctica and the other surrounding continents. Both factors, as well as the actual Isolation of Antarctica by deep water and the current system, and periods of interchange, radiation and extinction in the past, are reflected in the present-day marine biota on either side of the Drake Passage. This context represents a singular case of ecosystem change and evolution on our planet, and a great challenge to research.
    • Evaluating the isotopic niche of beaked whales from the southwestern South Atlantic and Southern Oceans

      Riccialdelli, L.; Viola, M.; Panarello, H.; Goodall, R. (2017)
      Marine Ecology Progress Series
      The study of species' niches is becoming increasingly important in ecological research with the growing need to understand how species and their habitat respond to rapid environmental changes. This kind of study is especially challenging in the case of oceanic and cryptic species such as beaked whales. We analyzed δ¹³C and δ¹⁵N values in bone collagen to study interspecific variation in the isotopic niche of 8 species of beaked whales (Berardius arnuxii, Hyperoodon planifrons, Mesoplodon bowdoini, M. grayi, M. hectori, M. layardii, Tasmacetus shepherdi and Ziphius cavirostris) that stranded along the coast of Tierra del Fuego, Argentina, between 1967 and 2009. We found a spatial (e.g. feeding areas) and trophic (e.g. diet) isotopic segregation among these species, which are known to inhabit subantarctic to Antarctic waters. Iso-topic analysis showed that, while spatial segregation seems to operate to a higher degree in species of the same genus (e.g. Mesoplodon), trophic differentiation allowed the co-existence of sympatric species from different genera (e.g. Ziphius, Hyperodoon and Mesoplodon). Our results agree with previous studies based on stomach content analyses. In addition to different trophic strategies, variation in habitat preferences were also revealed by stable isotope analysis. An isotopic trend in both δ¹³C and δ¹⁵N values was found among beaked whales and possible prey species in accordance with previous information on other cetacean species known to have feeding areas in different ocean regions. The present study provides valuable ecological information about elusive and little-studied beaked whale species inhabiting the world's southernmost oceans.