Dinucleotide microsatellite markers from the Antarctic seals and their use in other Pinnipeds

Twenty‐four microsatellite loci were isolated from three species of Antarctic seals (Subfamily Monachinae, Tribe Lobodontini). Eleven loci were cloned from Weddell seal, Leptonychotes weddellii, seven from leopard seal, Hydrurga leptonyx, and six from crabeater seal, Lobodon carcinophagus. Variability was assessed in Weddell seals collected in McMurdo Sound, leopard seals from Bird Island, South Georgia, and crabeater seals sampled in the eastern Ross Sea. All loci were variable in the three species used for cloning and 22 of these loci amplified variable products in the Ross seal, Ommatophoca rossii. Cross‐species amplification was largely successful, with an average of 19 loci amplifying products in other phocids.     

Unmasking Antarctic mollusc lineages: novel evidence from philinoid snails (Gastropoda: Cephalaspidea)

Since its introduction, the genus Philine has epitomized numerous mollusc snails with strong morphological convergence. Recently, a molecular analysis including a wide taxon sampling split this group into four non-sister families. Although they are especially diverse in cold and deep waters, no comprehensive studies are available for the Antarctic counterparts. Here, our morpho-anatomical and molecular data suggest major changes in the systematics of the group. From the eight known species, two are synonymized, Antarctophiline amoena with A. alata, and A. gouldi with A. gibba, and two are transferred to the genus Antarctophiline, namely A. apertissima comb.n. and A. falklandica comb.n. Two new species are described, A. easmithi sp.n. and A. amundseni sp.n. from different depths in the eastern Weddell Sea. The elusive P. antarctica from the Ross Sea was found in the Weddell Sea and Waegelea gen.n. is erected to place this species. Both phylogenetic and morphological data support the erection of Antarctophilinidae fam.n. to embrace most of the Philinoidea species described in the Southern Ocean. Only two species of Philinidae are found in Antarctic waters, Spiraphiline bathyalis gen. et sp.n. from bathyal depths in the Weddell Sea and S. kerguelensis comb.n. from the Kerguelen Islands. In light of the new data provided for all described species and the phylogenetic framework proposed herein, we briefly discuss the diversification and biogeographical patterns of Antarctic philinoid snails. Overall, antarctophilinid species seem to have restricted and grossly nonoverlapping distributions suggesting allopatric speciation connected possibly to geographical or bathymetric isolation.     

A new Antarctic association: the case of the hydroid Sarsia medelae (new sp.) associated with gorgonians

Sarsia medelae sp. nov. is described and illustrated from material collected in the Weddell Sea during the R/V Polarstern cruises ANT XVII/3 (April 2000) and in the Ross Sea during the R/V Italica cruise XIX (March 2004). The specimens have always been observed in association with several gorgonians of genera Thouarella sp., Primnoisis sp., and Notisis sp. The polyps of Sarsia medelae are considered as mesobiont of the gorgonian host with a non-parasitic relationship. It is the first time that this kind of association, which is so far only known from the Indian and Pacific Ocean, is reported in the Southern Ocean. This finding is discussed in the framework of the hypothesis that a part of Antarctic fauna has its origin in species dating back to before the Cretaceous period, because this kind of association between a hydroid and a gorgonian host being only known in the actual Antarctic shelf and in regions belonging to the previous Thethys areas.An erratum to this article can be found at     

Quantitative analysis of soft-bottom polychaetes of the Bellingshausen Sea and Gerlache Strait (Antarctica)

The basin off the Bellingshausen Sea, in contrast to other better known areas such as the Antarctic Peninsula and the Ross and Weddell Seas, has been little investigated due to remoteness and the prevalence of ice for most of the year. The present study focuses on an analysis of polychaetes collected from soft bottoms of this sea and off the west coast of the Antarctic Peninsula (Gerlache Strait) by means of a box-corer (25 × 25 cm) in two intensive surveys carried out during austral summers of 2002–2003 and 2005–2006 (BENTART-03 and BENTART-06). Three different polychaete assemblages were determined from the classification and ordination analyses of sampling stations based on the Bray-Curtis similarity index. One group of stations encompassed the deep stations from the shelf of the Bellingshausen Sea, the second one the shallower stations from the same area and the third one those stations located near the coast of Peter I Island and Gerlache Strait, off the Antarctic Peninsula. The environmental variables involved in segregating these groups were several sedimentary features (redox potential, gravel content) and depth. The present study provides further support to previous ones that considered the shelf of the Bellingshausen Sea as a differentiated region within the Southern Ocean, clearly distinct to the adjacent Weddell and Scott Seas and the Antarctic Peninsula.     

Persistent genetic signatures of historic climatic events in an Antarctic octopus

Repeated cycles of glaciation have had major impacts on the distribution of genetic diversity of the Antarctic marine fauna. During glacial periods, ice cover limited the amount of benthic habitat on the continental shelf. Conversely, more habitat and possibly altered seaways were available during interglacials when the ice receded and the sea level was higher. We used microsatellites and partial sequences of the mitochondrial cytochrome oxidase 1 gene to examine genetic structure in the direct‐developing, endemic Southern Ocean octopod Pareledone turqueti sampled from a broad range of areas that circumvent Antarctica. We find that, unusually for a species with poor dispersal potential, P. turqueti has a circumpolar distribution and is also found off the islands of South Georgia and Shag Rocks. The overriding pattern of spatial genetic structure can be explained by hydrographic (with ocean currents both facilitating and hindering gene flow) and bathymetric features. The Antarctic Peninsula region displays a complex population structure, consistent with its varied topographic and oceanographic influences. Genetic similarities between the Ross and Weddell Seas, however, are interpreted as a persistent historic genetic signature of connectivity during the hypothesized Pleistocene West Antarctic Ice Sheet collapses. A calibrated molecular clock indicates two major lineages within P. turqueti, a continental lineage and a sub‐Antarctic lineage, that diverged in the mid‐Pliocene with no subsequent gene flow. Both lineages survived subsequent major glacial cycles. Our data are indicative of potential refugia at Shag Rocks and South Georgia and also around the Antarctic continent within the Ross Sea, Weddell Sea and off Adélie Land. The mean age of mtDNA diversity within these main continental lineages coincides with Pleistocene glacial cycles.     

Antibodies against european phocine herpesvirus isolates detected in sera of Antarctic seals

Summary Neutralizing antibodies against European phocine herpesvirus were detected in sera of to two Antarctic seal species, Weddell seals (Leptonychotes weddellii) and crabeater seals (Lobodon carcinophagus), collected in the eastern Weddell Sea. A large number of positive sera crossneutralized canine herpesvirus, but only few sera also contained antibodies to feline herpesvirus. The Weddell seals suffered from a respiratory disease when the sera were collected (January–February, 1990). The significance and possible origin of herpesvirus infections in Antarctic seals documented for the first time in this communication is discussed. All sera were negative for antibodies against phocine and canine distemper viruses.     

Bryozoans of the Weddell Sea continental shelf,slope and abyss: did marine life colonize the Antarctic shelf from deep water,outlying islands or in situ refugia following glaciations?

Aim At the height of glaciations such as the Last Glacial Maximum (LGM), benthic life on polar continental shelves was bulldozed off nearly all of the Antarctic shelf by grounded ice sheets. The origins of the current shelf benthos have become a subject of considerable debate. There are several possible sources for the current Antarctic shelf fauna, the first of which is the continental slope and deep sea of the Southern Ocean. The high levels of reported eurybathy for many Antarctic species are taken as evidence supporting this. A second possible source for colonists is the southern margins of other continents. Finally, shelves could have been recolonized from refugia on the continental shelves or slopes around Antarctica. The current study investigates whether the patchily rich and abundant biota that now occurs on the Antarctic continental shelf recolonized from refugia in situ or elsewhere. Location Weddell Sea, Antarctica. Methods We examined bryozoan samples of the BENDEX, ANDEEP III and SYSTCO expeditions, as well as the literature. Using similarity matrices (Sørensen coefficient), we assessed similarities of benthos sampled from around Antarctica. By assessing numbers of species shared between differing depths and adjacent shelf areas, we evaluated the origins of cheilostome bryozoan communities. Results Bryozoans decreased from 28, 6.5 and 0.3 colonies per trawl, and 0.16, 0.046 and 0.0026 colonies per cm² of hard surface from shelf to slope to abyssal depths. We found little and no support for recolonization of the Weddell Sea shelf by bryozoans from the adjacent slope and abyss, in the scenario of LGM faunal wipe‐out. The Weddell Sea shelf bryozoan fauna was considerably more similar to those on other Antarctic shelves than to that of the adjacent (Weddell Sea) continental slope. The known bryozoan fauna of the Weddell Sea shelf is not a subset of the Weddell Sea slope or abyssal faunas. Main conclusions We consider that the composition of the current Weddell Sea bryozoan fauna is most easily explained by in situ survival. Thus we consider that at least some of the Weddell Sea fauna persisted throughout the LGM, although not necessarily at the same locations throughout, to recolonize the large area currently occupied.     

Composition and distribution of pelagic ostracods (Ostracoda: Myodocopa) in the Somov and Ross seas and adjacent waters of the Southern Ocean

The study of materials collected by Russian expeditions and literature data showed that the pelagic ostracod fauna of the Somov Sea, which lies south of the Antarctic Divergence (AD), is an impoverished complex of the fauna of the Australian-New Zealand Antarctic sector. While to the north of the AD the ostracod fauna includes species introduced from waters of the subantarctic and tropical-subtropical structures, ostracods of the Somov Sea are mainly typical Antarctic species. To the north and south of the AD, ostracod abundance and species richness are highest in the depth range of 200–500 m (especially at 300–400 m). Austrinoecia isocheira is the most common species in the Somov Sea and Alacia hettacra in the adjacent northern region. The more southerly Ross Sea has harsher environmental conditions than the Somov Sea and its ostracod fauna is a more impoverished complex of mainly Antarctic species. Alacia belgicae and A. isocheira are the dominant species in the Ross Sea, with their highest abundances at 200–300 m depths. The proportion of A. hettacra in the Ross Sea taxocene decreases southwards. The taxonomical composition and biogeographical structure of ostracod faunas change in the AD region at the northern boundaries of both seas.     

Some anatomical aspects of the cardiovascular system of antarctic seals and their possible functional significance in diving

The hearts and ascending aortae of 11 Weddell seals, Leptonychotes weddelli, three adult Crabeater seals, Lobodon carcinophagus, two adult Ross seals, Ommatophoca rossi, and one adult Leopard seal, Hydrurga leptonyx, were examined for comparison with terrestrial forms. The Weddell seal specimens were from animals ranging in age from midterm in fetal development to mature adults. All specimens were collected in 1971, 1972, and 1973, from McMurdo Sound and the Ross Sea, Antarctica. The phocid hearts were characteristically broader and flatter than those of other carnivore families and they tended toward bifid apices. The heart form indices (height/circumference) averaged 31.5 compared to 39.0 for felids. The right ventricular chambers of the Antarctic seals were found to average longer in Weddells and narrower in all, than those reported for four other carnivore families. An elastic enlargement was present in the ascending aortae of all seals. The largest diameter of the aortic bulb averaged 25.5 mm more than the base of the aorta in the adult Weddell seals which represented an increase of 72.5% over the base. It is suggested that the general heart form, and especially the ascending aortae, are anatomical adaptations to diving. The compressed heart makes possible unimpaired function when the chest is compressed during deep dives. The aortic bulb maintains mean arterial blood pressure and perfusion of the brain and cardiac tissue during diving bradycardia.     

Is the Scotia Sea a centre of Antarctic marine diversification? Some evidence of cryptic speciation in the circum-Antarctic bivalve <Emphasis Type="Italic">Lissarca notorcadensis</Emphasis> (Arcoidea: Philobryidae)

The bivalve Lissarca notorcadensis is one of the most abundant species in Antarctic waters and has colonised the entire Antarctic shelf and Scotia Sea Islands. Its brooding reproduction, low dispersal capabilities and epizoic lifestyle predict limited gene flow between geographically isolated populations. Relationships between specimens from seven regions in the Southern Ocean and outgroups were assessed with nuclear 28S rDNA and mitochondrial cytochrome oxidase subunit I (COI) genes. The 28S dataset indicate that while Lissarca appears to be a monophyletic genus, there is polyphyly between the Limopsidae and Philobryidae. Thirteen CO1 haplotypes were found, mostly unique to the sample regions, and two distinct lineages were distinguished. Specimens from the Weddell and Ross Sea form one lineage while individuals from the banks and islands of the Scotia Sea form the other. Within each lineage, further vicariance was observed forming six regionally isolated groups. Our results provide initial evidence for reproductively isolated populations of L. notorcadensis. The islands of the Scotia Sea appear to act as centres of speciation in the Southern Ocean.     

Redescription of the Antarctic springtail Desoria klovstadi using morphological and molecular evidence

Isotoma klovstadi Carpenter, 1902 was one of the first Collembola described from the Antarctic continent. It was first collected in November 1899 during the British Antarctic Expedition on the north coast of Victoria Land in the Ross Sea region. It is now known to occur in an extensive area of northern Victoria Land, including the offshore Possession, Coulman, and Foyn Islands. More recently, I. klovstadi was moved to the genus Gnathisotoma Cassagnau, 1957 and has been included in this genus in an unpublished checklist (online) of all described Collembola. Here, we redescribe the species and use morphological and molecular (COI and 18S genes) evidence to investigate its affinities within the Isotominae. We show that it does not belong to Gnathisotoma, or Isotoma s. str. (the viridis group) as currently conceived, but is likely to be part of the species complex of Isotoma s. lat. We discuss reasons for placing it in the genus Desoria Nicolet, 1841. Our results reinforce the already high level of endemicity in the Antarctic fauna and emphasise the value of both morphological and molecular studies in examining relict Gondwanan taxa and their evolutionary relationships with those of other Southern Hemisphere continents.     

Pycnogonids of the Eastern Weddell Sea (Antarctica), with remarks on their bathymetric distribution

The current work presents new data on the pycnogonids collected during the ANTXXI/2 cruise on board of “Polarstern” R/V during December 2003 and January 2004 in the Eastern Weddell Sea (Antarctica). Twenty-eight samples were taken, with different trawls, from depths between 120 and 1,866 m. In total, 251 specimens of pycnogonids, belonging to 31 species, were collected. Five species were observed to increase their depth range while six were found for the first time in the Weddell Sea, exhibiting an expansion in their geographical distribution, and confirming the general trend toward the circumpolarity of this group (23 of 31 species were circumpolar). Pallenopsis kupei is new for Antarctic waters. The most abundant species were Colossendeis megalonyx and Nymphon australe. Current data were completed with the samples collected from the same region during Polarstern cruise ANTXIII/3 (EASIZ I) in February–March 1996. Bathymetric patterns of distribution were analyzed for the total of 1,564 specimens (82 species, 14 genera). The results showed a difference in the composition between the continental shelf (from 100 to 900 m depth) and the slope (below 900 m), where the genus Nymphon dominated. Depth seems to be an influential factor in the structure of pycnogonid assemblages.     

New records of the rare shrimp parasite Zonophryxus quinquedens Barnard, 1913 (Crustacea, Isopoda, Dajidae): ecological and phylogenetic implications

The rare dajid, Zonophryxus quinquedens represents the only known isopod parasiting on shrimps in Antarctic waters. In contrast to the Bopyridae, which typically live in the gill cavity of their crab host, dajid isopods are normally attached to the carapace of the parasited shrimp. Four specimens of Z. quinquedens Barnard, 1913 were collected in the eastern and western Weddell Sea, Antarctica, during the expeditions ANT XXI/2 in 2003/2004 and ANT XXII/3 in 2005. Molecular phylogenetic analyses, based on small subunit rRNA gene sequences, indicate a close relationship of Z. quinquedens to the Bopyridae. Possible ecological and physiological aspects of the parasite–host interaction are discussed.     

Movements and diving behavior of weaned Weddell seal (Leptonychotes weddellii ) pups

Between 1993 and 1995, the diving behavior and movement patterns of 23 weaned Weddell seal pups (Leptonychotes weddellii) were tracked in the Ross Sea. Antarctica, using satellite-linked time-depth recorders. Regression analyses revealed that for seals of between 8 and 27 weeks old, age was poorly correlated with the dive depth, duration, or frequency. However, changes in dive parameters suggested that Weddell seal pups were attempting to maximize dive time, but the manner in which this was done depended on age and time of day. Movement patterns indicated that most Weddell seal pups left their natal area by the end of February, and traveled north along the Antarctic continent coastline. Several individuals returned to McMurdo Sound, but others were last located more than 400 km from McMurdo. Routes followed suggest that pups can use the pack ice habitat, but prefer to remain closer to the coastline than do adults. Accepted: 21 July 1998     

<Emphasis Type="Italic">Didemnum bentarti</Emphasis> (Chordata: Tunicata) a new species from the Bellingshausen Sea,Antarctica

A new Antarctic species belonging to the genus Didemnum is described. The material was collected during the BENTART-03 cruise through the Bellingshausen Sea. The geographic and bathymetric distribution of the known Didemnum species from Antarctic and Subantarctic regions and a tabular key for the identification of these species are summarized.     

Do bipolar distributions exist in marine sponges? Stylocordyla chupachups sp. nv. (Porifera: Hadromerida) from the Weddell Sea (Antarctic), previously reported as S. borealis (Lov��n, 1868)

Sponges are the dominant invertebrates in many Antarctic communities, where they play a decisive structural function thanks to their abundance and large sizes. However, current knowledge on Antarctic sponges remains poor even with respect to basic aspects such as taxonomy. Here, we report on an Antarctic species of the genus Stylocordyla, which has been recorded for a long time under the name of the boreal S. borealis due to spicule and growth habit similarities. A thorough study of dense populations of the only Stylocordyla species known up to now from the eastern zone of the Weddell Sea as well as the re-examination of several specimens (including the type material) of S. borealis has allowed us to assess the variability of the boreal species and to confirm that the austral species is not S. borealis (Lovén, 1868) but a new species of Stylocordyla, different from the other congeners recorded from southern latitudes. The new species S. chupachups commonly dwells on horizontal or slighted sloped hard bottoms of the continental shelf of Weddell Sea, from 100 m to below 400 m depth, although the densest populations usually occur between 150 and 300 m. It is a pioneer species in areas that have been scoured by icebergs, and thus its presence may be considered an indicator of recent colonisation.     

Evidence for high iron requirements of colonial Phaeocystis antarctica at low irradiance

We have carried out field and laboratory experiments to examine the iron requirements of colonial Phaeocystis antarctica in the Ross Sea. In December 2003, we performed an iron/light-manipulation bioassay experiment in the Ross Sea polynya, using an algal assemblage dominated by colonial Phaeocystis antarctica, collected from surface waters with an ambient dissolved Fe concentration of ∼0.4 nM. Results from this experiment suggest that P. antarctica growth rates were enhanced at high irradiance (∼50% of incident surface irradiance) but were unaffected by iron addition, and that elevated irradiance mediated a significant decrease in cellular chlorophyll a content. We also conducted a laboratory iron dose–response bioassay experiment using a unialgal, non-axenic strain of colonial P. antarctica and low-iron (<0.2 nM) filtered seawater, both collected from the Ross Sea polynya in December 2003. By using rigorous trace-metal clean techniques, we performed this dose–response iron-addition experiment at ∼0°C without using organic chelating reagents to control dissolved iron levels. At the relatively low irradiance of this experiment (∼20 μE m⁻² s⁻¹), estimated nitrate-specific growth rate as a function of dissolved iron concentration can be described by a Monod relationship, yielding a half-saturation constant with respect to growth of 0.45 nM dissolved iron. This value is relatively high compared to reported estimates for other Antarctic phytoplankton. Our results suggest that seasonal changes in the availability of both iron and light play critical roles in limiting the growth and biomass of colonial Phaeocystis antarctica in the Ross Sea polynya.     

The role of notothenioid fish in the food web of the Ross Sea shelf waters: a review

The Ross Sea, a large, high-latitude (72–78°S) embayment of the Antarctic continental shelf, averages 500 m deep, with troughs to 1,200 m and the shelf break at 700 m. It is covered by pack ice for 9 months of the year. The fish fauna of about 80 species includes primarily 4 families and 53 species of the endemic perciform suborder Notothenioidei. This review focuses on the diet and role in the food web of notothenioids and top-level bird and mammal predators, and also includes new information on the diets of artedidraconids and bathydraconids. Although principally a benthic group, notothenioids have diversified to form an adaptive radiation that includes pelagic and semipelagic species. In the southern Ross Sea, notothenioids dominate the fish fauna at levels of abundance and biomass >90% and are, therefore, inordinately important in the food web. Antarctic krill (Euphausia superba) and mesopelagic fishes are virtually absent from the shelf waters of the Ross Sea. Of the four notothenioid families, nototheniids show the most ecological and dietary diversification, with pelagic, cryopelagic, epibenthic and benthic species. Neutrally buoyant Pleuragramma antarcticum constitutes >90% of both the abundance and biomass of the midwater fish fauna. Most benthic nototheniids are opportunistic and feed on seasonally or locally abundant zooplanktonic prey. Artedidraconids are benthic sit-and-wait predators. Larger bathydraconids are benthic predators on fish while smaller species feed mainly on benthic crustaceans. Channichthyids are less dependent on the bottom for food than other notothenioids. Some species combine benthic and pelagic life styles; others are predominantly pelagic and all consume euphausiids and/or fish. South polar skuas, Antarctic petrels, Adélie and emperor penguins, Weddell seals and minke and killer whales are the higher vertebrate components of the food web, and all prey on notothenioids to some extent. Based on the frequency of occurrence of prey items in the stomachs of fish, bird and mammal predators, P. antarcticum and ice krill E. crystallorophias are the key species in the food web of the Ross Sea. P. antarcticum is a component of the diet of at least 11 species of nototheniid, bathydraconid and channichthyid fish and, at frequencies of occurrence from 71 to 100%, is especially important for Dissostichus mawsoni, Gvozdarus svetovidovi and some channichthyids. At least 16 species of notothenioids serve as prey for bird and mammal predators, but P. antarcticum is the most important and is a major component of the diet of south polar skua, Adélie and emperor penguins and Weddell seals, at frequencies of occurrence from 26 to 100%. E. crystallorophias is consumed by some nototheniid and channichthyid fish and can be of importance in the diet of emperor and Adélie penguins, although in the latter case, this is dependent on location and time of year.Unlike the linear phytoplanktonE. superbaconsumers of the E. superba food chain hypothesized for much of the Southern Ocean, the food web of the Ross Sea shelf is non-linear, with complex prey-predator interactions. Notothenioid fish play a key role: as predators, they occupy most of the trophic niches available in the ecosystem, relying on benthic, zooplanktonic and nektonic organisms; as prey, they are important food resources for each other and for most top predators living and foraging on the shelf. They also constitute the major link between lower (invertebrates) and higher (birds and mammals) levels of the food web. This is especially true for P. antarcticum. Along with E. crystallorophias, its ecological role in the Ross Sea is equivalent to that of myctophids and E. superba elsewhere in the Southern Ocean.     

Oocyte development and gonad production of Nematocarcinus lanceopes (Decapoda: Caridea) in the eastern Weddell Sea, Antarctica

 Nematocarcinus lanceopes Bate 1888 is the only decapod that occurs in large numbers on the continental slope of the Weddell Sea, Antarctica. Histological examination of the female gonads and analyses of oocyte growth indicate a biannual reproduction cycle with seasonal occyte maturation in this species. Vitellogenic development is estimated to take 2 years and culminates during summer. Females spawn three times, every 2nd year, while they grow from 27 to 34 mm carapace length. Based on these results the calculated female gonad production is 184 g wet mass (70.5 g dry mass)/total catch, which is high compared to shrimp populations on the continental shelf of the Weddell Sea. Seasonal reproductive patterns of N. lanceopes seem to reflect oscillating food conditions in the Antarctic Weddell Sea. This mode of reproduction differs from all other Nematocarcinidae, which release eggs the whole year round. The ability to adapt the reproductive cycle to a seasonal productivity pattern may have been an important factor in extending the distribution range of the deep-water genus Nematocarcinus into Antarctic waters. Received: 3 January 1996/Accepted: 28 April 1996