A new species of Hormathia (Actiniaria, Hormathiidae) from the eastern Weddell Sea, Antarctica

A new species of sea anemone in the genus Hormathia, is described and illustrated based on forty-two specimens collected during the Polarstern cruises ANT XV/3 and ANT XVII/3 in the Weddell Sea. The main features of the new taxon are the crown of flattened and hooked tubercles at the distal end of the scapus, the regular arrangement of pointed tubercles along the column and the cnidom. The new species shares the pointed tubercles, at least in the upper part of the scapus, with two other species of Hormathia in the southern hemisphere: Hormathia spinosa Hertwig 1882 and H. pectinata Hertwig 1882 Received in revised form: 27 December 2000 Electronic Publication     

Records of echinoderms (excluding holothurians) from the Norfolk Ridge and Three Kings Rise north of New Zealand

Abstract

Fifty-eight species of echinoderms (excluding holothurians) are newly recorded from the southern Norfolk Ridge and the Three Kings Rise to the north of New Zealand. Two species of Asteroidea, in the genera Ceramaster and Pseudoceramaster, ceramaster are described as new. A total of 115 species of echinoderms, not counting the holothurians, are now known from this area. They include 14 crinoids, 35 asteroids, 41 ophiuroids, and 25 echinoids.     

Achilaophonte maxima gen.n., spec.n., a new taxon of the Laophontidae (Copepoda,harpacticoida) from the high Antartic (Weddell Sea)

Male and female of a new genus and species of the family Laophontidae, Archilaophonte maxima, are described. The specimen was found in the high Antartic (Weddell Sea) and apprears to be the most primitive genus up to now within the superfamily Laophontoidea as defined by Huys (1990). Based on its setation of legs and mouth parts, however, it can be placed unequivocally into the family Laophontidae. Archilaophonte maxima gen. n. shows close affinities to the laophontid genus Esola Edwards 1891. Both genera form a monophyletic group which is interpreted here as the first and most primitive offshot in the evolution of the Laophontidae. The synapomorphies of the former lineage are the shape of the protopodite of the P1 and shape and setation of the female P5.     

Phytoplankton dynamics in relation to hydrography, nutrients and zooplankton at the onset of sea ice formation in the eastern Weddell Sea (Antarctica)

The quantitative and qualitative distribution of phytoplankton was investigated along five North–South transects in the eastern Weddell Sea during the transition from late autumn to winter. Relationships with the regional hydrography, progressing sea ice coverage, nutrient distribution and zooplankton are discussed and compared with data from other seasons. To the north of the Antarctic Slope Front (ASF) a remnant temperature minimum layer was found above the primary pycnocline throughout summer. Surface waters had not entirely acquired typical winter characteristics. While temperature was already in the winter range, this was not the case for salinity. Highest biomass of phytoplankton, with the exception of the first transect, was found in the region adjoining the ASF to the north. Absolute chlorophyll a (Chl a) concentrations dropped from 0.35 to 0.19 g l^–1 . Nutrient pools exhibited a replenishing tendency. Ammonium concentrations were high (0.75–2 mol l^–1), indicating extensive heterotrophic activity. The phytoplankton in the ASF region was dominated by nanoflagellates, particularly Phaeocystis spp.. North of the ASF the abundance of diatoms increased, with Fragilariopsis spp., F. cylindrus and Thalassiosira spp. dominating. Community structure varied both due to hydrographical conditions and the advancing ice edge. The phytoplankton assemblage formed during late autumn were very similar to the ones found in early spring. A POC/PON ratio close to Redfield, decreasing POC concentration and a high phaeophytin/Chl a ratio, as well as a high abundance of mesozooplankton indicated that a strong grazing pressure was exerted on the phytoplankton community. A comparison between primary production (PP) in the water column and the sea ice showed a shift of the major portion of PP into the ice during the period of investigation.     

Coulmannia rossensis sp. n. (Isopoda, Asellota, Paramunnidae) from the Ross Sea, Southern Ocean

A new species of Coulmannia, Coulmannia rossensis, is described from the Ross Sea, Antarctica. It is most similar to Coulmannia ramosae Castelló, 2004, but can easily be distinguished from this species bythe males yielding a pair of granulate humps on the dorsum of the pereonites 1-6 and a single granulate hump on the pereonite 7 and the free pleonite. Coulmannia rossensissp. n. is sexually dimorphic. The dorsal sculpture of the female bodies yield a single granulate hump on all the pereonites and free pleonite. The species of the genus Coulmannia are restricted to the Southern Ocean, and Coulmannia rossensissp. n. is the fourth species included in it.     

Benthic isopods (Crustacea,Malacostraca) from the Ross Sea,Antarctica: species checklist and their zoogeography in the Southern Ocean

In this study isopod species of the Ross Sea were investigated. Literature until May 2008 was checked to provide an overview of all known and described species in the Ross Sea. This species checklist was then enlarged through material of the 19th Italica expedition in 2004. During this expedition for the first time a small mesh net (500 μm) was used. Nine thousand four hundred and eighty one isopod specimens were collected during this expedition. Through this material the number of isopod species in the Ross Sea increased from 42 to 117 species, which belong to 20 families and 49 genera. Fifty-six percentage of the isopods species collected during the Italica expedition are new to science. The zoogeography of the 117 species was investigated. A non-transformed binary presence-absence data matrix was constructed using the Bray–Curtis coefficient. The results were displayed in a cluster analysis and by nonmetric multidimensional scaling (MDS). This paper gives a first insight into the occurrence and distribution of the isopod species of the Ross Sea.     

Temporal and spatial variation of dominant pelagic Copepoda (Crustacea) in the Weddell Sea (Southern Ocean) 1929 to 1993

The abundances of four dominant Antarctic copepod species, Metridia gerlachei, Rhincalanus gigas, Calanoides acutus and Calanus propinquus, were examined in the Southern Ocean in a combination of a literature review, analysis of museum samples and field sampling. The data were analysed for spatial and temporal variations. The data included in the analysis were from the Weddell Sea area in the summertime at periods 1929–1939 and 1989–1993. The results are discussed in the light of environmental changes and their hypothesised and observed consequences in the Southern Ocean: global temperature change, ozone deficiency and cascading trophic interactions. Combining all these hypothetical effects our null hypothesis was that there were no consistent long-term changes in the abundance of dominant pelagic Copepoda. The null hypothesis was rejected, since several taxons did show statistically significant long-term changes in abundance. The changes were not uniform however. The numbers of adults and juveniles of Calanus propinquus increased significantly between the periods studied. Adult stages of Calanoides acutus were the only taxon decreasing in abundance, in concert with the cascading trophic interactions theory. Latitudinally, only Metridia gerlachei showed a significant increase from north to south. Longitudinally, the abundances of Calanus propinquus juveniles and both adults and juveniles of Rhincalanus gigas increased from west to east. There were no significant variations between day and night samples. Interannual changes were statistically significant in juvenile stages of all the species and in adults of Calanus propinquus. We conclude that no uniform and consistent abundance changes could be observed in the pelagic Copepoda of the Weddell Sea that could be connected to major environmental changes, expected to affect the whole planktonic ecosystem of the Southern Ocean. Significant changes in some of the species studied show that the pelagic ecosystem is not in a steady state, but in addition to interannual changes, there are also major fluctuations extending over decades. Received: 5 December 1996 / Accepted: 24 March 1997     

Zoobenthos of the Cheshskaya Bay (southeastern Barents Sea): spatial distribution and community structure in relation to environmental factors

Structural and functional characteristics of zoobenthos of the Cheshskaya Bay (SE Barents Sea) were studied at 21 stations in June/July 1995. Strong prevailing cyclonic and tidal currents result in relatively uniform temperature and salinity in the area. Sediments consist mainly of sand and pebbles, while the flux of suspended matter from rivers locally increases the share of finer fractions. Analysis of species composition (419 taxa), abundance (up to 4,200 ind m⁻² and up to 29,000 ind m⁻² with juveniles) and biomass (up to >6,000 g wet wt m⁻²) indicates high species richness in most parts of the bay, especially in the northeast. Analysis of community structure using production characteristics of species revealed a general predominance of suspension feeders partitioned into seven communities. The dominant species of these communities were Mytilus edulis and Balanus crenatus (Type 1), B. crenatus (Type 2), Modiolus modiolus and Verruca stroemia (Type 3), Flustra foliacea and V. stroemia (Type 4), Hydrallmania falcata (Type 5), V. stroemia and Chirona hameri (Type 6), and Ophelia limacina (Type 7). The structure of the communities is mainly regulated by sediment type, water depth and, to some extent, by riverine input. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Distribution of living planktonic foraminifera in the Ross Sea and the Pacific sector of the Southern Ocean (Antarctica)

In order to determine the factors controlling the distribution of planktonic foraminifera as a proxy for reconstruction of paleoenvironments, we present data on live assemblages collected in the Southern Ocean. Plankton tows and hydrographic measurements were taken in the upper 400 m of the water column at different sites in the Ross Sea (site B) and at the Polar Front of the Pacific Ocean (site O) during austral summers from 1998 to 2003.Based on qualitative micropaleontological observations we discriminated between Neogloboquadrina pachyderma dextral (dex) and N. pachyderma sinistral (sin). In addition for N. pachyderma (sin) we distinguished four morphs: the first one (1) has a thickened test and depressed sutures; the second morph (2) is represented by specimens characterized by a subspheric and heavily encrusted test; the third morph (3) has a thin and lobate walled test; the fourth one (4) represent the juvenile stage of N. pachyderma (sin) and is characterized by a smaller average size.The microfauna collected in the Ross Sea (site B) is characterized by the dominance of N. pachyderma (sin) (morphs 1 and 2), whereas low occurrences of Turborotalia quinqueloba, N. pachyderma (dex) and Neogloboquadrina dutertrei were noted in the first 50 m of the water column. The water column at this station is characterized by a marked and shallow stratification and a marked thermocline during the sampling season.At the ocean station (site O), the assemblage shows increasing diversification: T. quinqueloba, G. bulloides, N. pachyderma (dex) and few specimens of Globigerinita uvula characterize the planktonic microfauna. There is a predominance of non-encrusted morphs and juvenile specimens (3 and 4). At this station the mixed surface layer is deeper than in the Ross Sea (60–70 m), the pycnocline and the thermocline less marked.The depth and the intensity of the Deep Chlorophyll Maximum (DCM) influence foraminiferal distribution: N. pachyderma (sin) shows abundance peaks at or just below the DCM while G. bulloides peaks above the DCM. Coiling direction of N. pachyderma seems to be not controlled exclusively by Sea Surface Temperature (SST): probably the two coiling types are genetically different.Results document that diversity of planktonic foraminifera, number of specimens and variations in test morphology are related to regional differences in water properties (temperature, salinity, and DCM depth).     

Seasonal variation in the distribution and abundance of Oithona and Oncaea species (Copepoda,Crustacea) in the southeastern Weddell Sea,Antarctica

The coupling between the seasonal distribution of dominant Oithonidae and Oncaeidae and the prevailing environmental conditions in the eastern Weddell Sea was investigated. In samples from February, a community on the shelf and in the oceanic surface layer, consisting mainly of Oithona similis and Oncaea curvata and juveniles of both genera, could be differentiated from a community found in deeper oceanic waters, consisting of Oithona frigida, Oncaea parila, Oncaea antarctica and Oncaea englishi. In November the differences in the species distribution between the two regions were less pronounced and the abundances of all species were much lower than earlier in the year. The dominant species were Oithona similis, which reached abundances of up to 182/m³ in February, and Oncaea curvata with up to 215/m³. Deeper living species were comparatively rare. Oithona similis occurred mainly in the top 200 m during both seasons. The other species, by contrast, were generally deeper and more dispersed through the water column in late winter than in summer.     

Antarctic Starfish (Echinodermata, Asteroidea) from the ANDEEP3 expedition

This dataset includes information on sea stars collected during the ANDEEP3 expedition, which took place in 2005. The expedition focused on deep-sea stations in the Powell Basin and Weddell Sea.Sea stars were collected using an Agassiz trawl (3m, mesh-size 500µm), deployed in 16 stations during the ANTXXII/3 (ANDEEP3, PS72) expedition of the RV Polarstern. Sampling depth ranged from 1047 to 4931m. Trawling distance ranged from 731 to 3841m. The sampling area ranges from -41°S to -71°S (latitude) and from 0 to -65°W (longitude). A complete list of stations is available from the PANGAEA data system (http://www.pangaea.de/PHP/CruiseReports.php?b=Polarstern), including a cruise report (http://epic-reports.awi.de/3694/1/PE_72.pdf).The dataset includes 50 records, with individual counts ranging from 1-10, reaching a total of 132 specimens.The andeep3-Asteroidea is a unique dataset as it covers an under-explored region of the Southern Ocean, and that very little information was available regarding Antarctic deep-sea starfish. Before this study, most of the information available focused on starfish from shallower depths than 1000m. This dataset allowed to make unique observations, such as the fact that some species were only present at very high depths (Hymenaster crucifer, Hymenaster pellucidus, Hymenaster praecoquis, Psilaster charcoti, Freyella attenuata, Freyastera tuberculata, Styrachaster chuni and Vemaster sudatlanticus were all found below -3770m), while others displayed remarkable eurybathy, with very high depths amplitudes (Bathybiaster loripes (4842m), Lysasterias adeliae (4832m), Lophaster stellans (4752m), Cheiraster planeta (4708m), Eremicaster crassus (4626m), Lophaster gaini (4560m) and Ctenodiscus australis (4489m)).Even if the number of records is relatively small, the data bring many new insights on the taxonomic, bathymetric and geographic distributions of Southern starfish, covering a very large sampling zone. The dataset also brings to light six species, newly reported in the Southern Ocean.The quality of the data was controlled very thoroughly, by means of on-board Polarstern GPS systems, checking of identification by a renowned specialist (Prof. Michel Jangoux, Université Libre de Bruxelles), and matching to the Register of Antarctic Marine Species (RAMS) and World Register of Marine Species (WoRMS). The data is therefore fit for completing checklists, for inclusion in biodiversity patterns analysis, or niche modeling. It also nicely fills an information gap regarding deep-sea starfish from the Southern Ocean, for which data is very scarce at this time. The authors may be contacted if any additional information is needed before carrying out detailed biodiversity or biogeographic studies.     

Sea surface distribution of coccolithophores in the eastern Pacific sector of the Southern Ocean (Bellingshausen and Amundsen Seas) during the late austral summer of 2001

Horizontal distributions of coccolithophores were observed in sea surface water samples collected on the RV Polarstern between 27 February and 10 April, 2001, in the Pacific sector of the Southern Ocean (Bellingshausen and Amundsen Seas). These samples were analyzed to gain information about the distribution of coccolithophores in relation to the oceanic fronts of the Southern Ocean. A total of fifteen species of coccolithophores were identified, showing cell abundances of up to 67 × 10³ cells/l down to 63°S. Emiliania huxleyi was the most abundant taxon, always accounting for more than 85% of the assemblage. The second most abundant species was Calcidiscus leptoporus, with values lower than 7%. Cell density increases significantly in both the Subantarctic and Polar Fronts (155 and 151 × 10³ cells/l, respectively), decreasing abruptly in the intervening Polar Frontal Zone and to the south of the Polar Front. Although temperature at high latitudes is the main factor controlling the biogeographical distribution of coccolithophores, at the regional level (Southern Ocean) the frontal systems, and consequently nutrient distribution, play a crucial role.     

Synopsis of a new collection of sea spiders (Arthropoda: Pycnogonida) from the Ross Sea,Antarctica

The biodiversity research expedition TAN0204 with RS Tangaroa to the Ross Sea in 2004 yielded a new collection of 2,687 specimens of pycnogonids. As much as 25 different species encompassing 14 genera and eight families were identified and their records are discussed herein. The collection is archived in the Marine Invertebrate Collection of the New Zealand National Institute of Water and Atmospheric Research (NIWA). The majority (69%) of specimens are from the Nymphon australe group (Nymphonidae), although species richness and abundance varied among the stations sampled. The collection includes several specimens from polymerous taxa; Pentanymphon antarcticum (Nymphonidae), Decolopoda australis (Colossendeidae) and Pentapycnon bouvieri (Pycnogonidae). All species were classified based on morphological characters, and DNA sequences (from the 18S, 12S, 16S and COI regions) for 21 of the representative morphotypes are given. The DNA sequences confirmed the species-level distinctiveness of these morphotypes. No species new to science were identified, although further detailed morphometric and/or molecular analyses may reveal cryptic or sibling species, especially in species such as the highly abundant Nymphon australe group. An erratum to this article can be found at     

Description of a new genus and species of zoarcid fish, <Emphasis Type="Italic">Bellingshausenia olasoi</Emphasis>, from the Bellingshausen Sea (Southern Ocean)

A new genus and species of zoarcid fish, Bellingshausenia olasoi, is described on the basis of five specimens collected from the Bellingshausen Sea, Southern Ocean, at depths of 602–615 m. Bellingshausenia is a lycodine that can be distinguished from all other zoarcid genera by the following combination of characters: seven branchiostegal rays, scapular foramen open, cranium narrowed, smooth ceratohyal-epihyal articulation, palatal arch well developed, supratemporal commissure and occipital pores absent, intercalar reduced and displaced backward and parasphenoid wing high. The relationships of the new genus are discussed.     

Cumaceans (Crustacea) from the Bellingshausen Sea and off the western Antarctic Peninsula: a deep-water link with fauna of the surrounding oceans

During the austral summers of 2003 and 2006, two cruise were carried out in the Bellingshausen Sea and west off Antarctic Peninsula on board of RV Hespérides. Samples were collected at 26 stations with a multinet Macer-GIROQ sled. A total of 557 cumaceans belonging to 36 species of five families were collected. Nannastacidae was the most abundant and speciose family. Hemilamprops pellucidus and Cyclaspis gigas were the most frequently collected species (38.5% of sampling stations). Cumella asutralis reached the highest density (514.7 individuals/1,000 m² at stn 7). Maximum species richness (S = 15) and diversity (H′ = 3.53) was observed at one of the deepest station. Positive correlations were found between the cumacean distribution and the organic content and percentage of coarse sand of the sediments. Predominance of Nannastacidae in front of other cumaceans could be explained by their type of feeding (i.e. predators or scavengers), which may be more successful in the deep seafloor of an oligotrophic sea such as studied herein. The presence in the deepest sampling sites of species shared with faunas of surrounding oceans suggests a link between these faunas and those of deep Antarctic waters.