Benthic hydroids (Cnidaria, Hydrozoa) from off Bouvet Island (Antarctic Ocean)

Twenty-seven species of benthic hydroids have been found in a small collection from off Bouvet Island (Antarctic Ocean). The material was obtained during the XXI/2 German Antarctic expedition with R.V. Polarstern 2003–2004. Of the 27 species collected, 21 were unknown from those waters. Consequently, the number of known species of benthic hydroids from the area has risen to 32, representing a high diversity location for this group in the Southern Ocean considering the sampling effort made. All species, including those previously known from Bouvet waters, are considered with respect to geographical distribution.The present work is an addition to the special issue “Macrobenthic studies at Bouvet island”, presenting work carried out from on board RV Polarstern in 2003/2004 and published in Polar Biology 29 (2006)     

A new species and new records of lithodid crabs (Crustacea: Decapoda: Lithodidae) from the Crozet and Kerguelen Islands area (Subantarctica)

Four species of lithodid crabs from waters (240–2,005 m) in the Crozet and Kerguelen Islands area were studied. One new species, Neolithodes duhameli, is described. Three other species, N. capensis Stebbing, Paralomis anamerae Macpherson and P. birsteini Macpherson are reported for the first time from these localities. The new species, N. duhameli (620–1,500 m), is the fourth representative of the genus in Subantarctic waters and belongs to the group of species possessing a carapace, chelipeds and walking legs covered with numerous spinules or spiniform granules in addition to spines. However, the new species is distinguishable from others in the genus by the long, strong spines on the carapace and pereiopods. The finding of two species of Paralomis clearly extends their geographic ranges in the Southern Ocean: P. anamerae was previously known only in waters of the Falkland Islands and the circumpolar distribution of P. birsteini is supported. The observation of N. capensis also extends its previously described range from South Africa, in the Cape region, to Subantarctic waters. As a result of this study, 14 species of the family Lithodidae are now known from Antarctic and Subantarctic waters; and most can be considered endemic to these waters.     

Encounter of lithodid crab <Emphasis Type="Italic">Paralomis birsteini</Emphasis> on the continental slope off Antarctica,sampled by ROV

A population of stone crab (Lithodidae) was encountered on the continental slope off Antarctica in the Bellingshausen Sea between 1,123 and 1,304 m water depths using the ROV-Isis during leg 166 of the RV James Clark Ross, in January 2007. Specimens were video recorded and one specimen was retrieved by ROV for morphological and molecular identification. Based on morphology and molecular data from the mitochondrial COI gene, this specimen identified as P. birsteini, Macpherson, 1988a. The significance of the molecular data and their implications for biogeography and evolution of lithodids in the Southern Ocean are briefly discussed.     

New findings of <Emphasis Type="Italic">Lophius litulon</Emphasis> (Lophiidae) off the Southern Kurils

Data on new captures of juveniles of the yellow anglerfish Lophius litulon off the Southern Kurils are presented. Outer morphological characters of the specimens caught in waters off the Southern Kurils are described in comparison with those of specimens from other regions of the north-western part of the Pacific Ocean. Probable pathways of penetration of anglerfish (Lophiidae) to Russian Far East waters are discussed.     

The surface structure of Antarctic fish eggs and its use in identifying fish eggs from the Southern Ocean

Summary The surface structure of eggs of Notothenia neglecta, Nototheniops larseni, Nototheniops nudifrons (Nototheniidae), Champsocephalus gunnari and Chaenocephalus aceratus (Channichthyidae), collected near Elephant Island (Atlantic sector of the Southern Ocean) and of Notothenia rossii rossii (Nototheniidae) from Kerguelen waters (Indian sector of the Southern Ocean) was studied by scanning electron microscopy (SEM). Eggs of N. larseni differed from the other species by containing a micropyle with two micropyle pits. External morphological characteristics of the egg envelope such as the ultrastructure of the zona radiata, its interpore distances and the diameter of the micropyle were species-specific and could aid in the identification of fish eggs collected from the Southern Ocean.     

A phytoplankton absorption-based primary productivity model for remote sensing in the Southern Ocean

Recent global environmental changes such as an increase in sea surface temperature (SST) are likely to impact primary productivity of phytoplankton in the Southern Ocean. However, models to estimate net primary production using satellite data use SST and uncertain estimation of chlorophyll a (chl-a) concentration. A primary productivity model for satellite ocean color data from the Southern Ocean, which is based on the light absorption coefficient of phytoplankton to reduce uncertainties of sea surface chl-a estimations and bias in optimal values of chl-a normalized productivity derived from SST, has been developed. The new model was able to estimate net primary productivity in the water column (PP _eu) without dependency on temperature when in the range of −2 to 25°C, and it explained 51% of the observed variability in PP _eu with a root mean square error (RMSE) of 0.15. Application of the model revealed that the SST dependent model has overestimated PP _eu in warmer waters around the Subtropical Front, and underestimated PP _eu in colder waters poleward of the Sub-Antarctic Front. This absorption-based primary productivity model contributes to a study of the relationship among spatio-temporal variations in the physical environment, and biogeochemical cycles in the Southern Ocean.     

Two new gorgonian genera (Octocorallia: Primnoidae) from Southern Ocean waters

Tauroprimnoa austasensis gen. nov., sp. nov. and Digitogorgia kuekenthali gen. nov., sp. nov. are described and illustrated from Southern Ocean waters. The most distinctive characters of the newly proposed genera are, in Tauroprimnoa, the existence of four marginal scales, two abaxials with a strong thorn, and the presence of a single abaxial longitudinal row of body scales. In the case of Digitogorgia, the colony branching pattern, the structure of the opercular scales, and the presence of a complete cycle of accessory opercular scales are the distinct features to distinguish it from previously known genera. Tauroprimnoa austasensis sp. nov. is reported from the Eastern Weddell Sea, Antarctica, while Digitogorgia kuekenthali sp. nov. has been found in the SubAntarctic waters off Burdwood Bank and, in the south east of Isla Nueva in Chilean Patagonia.     

Characterization of the exoskeleton of the Antarctic king crab Paralomis birsteini

Ocean acidification is projected to inhibit the biogenic production of calcium carbonate skeletons in marine organisms. Antarctic waters represent a natural environment in which to examine the long‐term effects of carbonate undersaturation on calcification in marine predators. King crabs (Decapoda: Anomura: Lithodidae), which currently inhabit the undersaturated environment of the continental slope off Antarctica, are potential invasives on the Antarctic shelf as oceanic temperatures rise. Here, we describe the chemical, physical, and mechanical properties of the exoskeleton of the deep‐water Antarctic lithodid Paralomis birsteini and compare our measurements with two decapod species from shallow water at lower latitudes, Callinectes sapidus (Brachyura: Portunidae) and Cancer borealis (Brachyura: Cancridae). In Paralomis birsteini, crabs deposit proportionally more calcium carbonate in their predatory chelae than their protective carapaces, compared with the other two crab species. When exoskeleton thickness and microhardness were compared between the chelae and carapace, the magnitude of the difference between these body regions was significantly greater in P. birsteini than in the other species tested. Hence, there appeared to be a greater disparity in P. birsteini in overall investment in calcium carbonate structures among regions of the exoskeleton. The imperatives of prey consumption and predator avoidance may be influencing the deposition of calcium to different parts of the exoskeleton in lithodids living in an environment undersaturated with respect to calcium carbonate.     

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     

A description of larval and early juvenile development in Paralomis spinosissima (Decapoda: Anomura: Paguroidea: Lithodidae) from South Georgia waters (Southern Ocean)

The early ontogenetic stages of Paralomis spinosissima Birstein and Vinogradow, 1972, are described in detail and illustrated, with notes on morphological variability observed. Larval and early juvenile development was described to the crab I instar reared under controlled conditions of temperature and food supply. The abbreviated larval development invariably passed through two zoeal stages and the benthic megalopa stage. The larval development was completed without food supply, and food Artemia nauplii were first given after moult to the crab-I stage. Simplification and retarded development of the mouthparts are discussed as a function of lecithotrophy of these larvae and based on morphology no facultative feeding mode is suggested. Lecithotrophy in the Southern Ocean Lithodidae is discussed to be an adaptation allowing independence from seasonal food availability at high latitudes.     

The ectoparasitic barnacle Anelasma (Cirripedia,Thoracica, Lepadomorpha) on the shark Centroscyllium nigrum (Chondrichthyes,Squalidae) from the Pacific sub-Antarctic

We report the occurrence of the ectoparasitic lepadomorph barnacle Anelasma sp. on the deep-sea squaloid shark Centroscyllium nigrum from the Pacific sub-Antarctic off southern Chile. Anelasma has previously been documented only from the northeast Atlantic on the squaloid shark Etmopterus spinax; this new record extends the known range of Anelasma into the Pacific Ocean and into the Southern Hemisphere, and documents a new host for this parasitic barnacle.     

Mysterious bio-duck sound attributed to the Antarctic minke whale (Balaenoptera bonaerensis)

For decades, the bio-duck sound has been recorded in the Southern Ocean, but the animal producing it has remained a mystery. Heard mainly during austral winter in the Southern Ocean, this ubiquitous sound has been recorded in Antarctic waters and contemporaneously off the Australian west coast. Here, we present conclusive evidence that the bio-duck sound is produced by Antarctic minke whales (Balaenoptera bonaerensis). We analysed data from multi-sensor acoustic recording tags that included intense bio-duck sounds as well as singular downsweeps that have previously been attributed to this species. This finding allows the interpretation of a wealth of long-term acoustic recordings for this previously acoustically concealed species, which will improve our understanding of the distribution, abundance and behaviour of Antarctic minke whales. This is critical information for a species that inhabits a difficult to access sea-ice environment that is changing rapidly in some regions and has been the subject of contentious lethal sampling efforts and ongoing international legal action.     

Revision of the bathyal fish genusHomostolus (Ophidiiformes,Ophidiidae)

The ophidiid fish genusHomostolus is revised on the basis of 44 specimens. Meristic and morphometric characters strongly indicate that the genus as presently known contains a single species,Homostolus acer Smith et Radcliffe, 1913, withHomostolus japonicus Matsubara, 1943, reduced to synonymy. Geographical variations found in certain meristic characters indicate thatH. acer expanded its range from Philippine waters into both northern and southern waters. The species is distributed on deep-sea floors from the Pacific Ocean off central Japan, to the Indian Ocean off northern Western Australia, and to the Tasman Sea off New South Wales, at bathyal depths from about 400 to 700 m.     

Pelagic fish distribution and ontogenetic vertical migration in common mesopelagic species off Lützow-Holm Bay (Indian Ocean sector,Southern Ocean) during austral summer

The horizontal and vertical distributions of fish were examined off Lützow-Holm Bay in the Indian Ocean sector of the Southern Ocean during midnight sun in January 2005. Fish were sampled from six discrete depth layers (0–2,000 m). The most abundant fish in layers from the surface to 200 m were larval stages of Electrona antarctica and Notolepis coatsi. In layers from 200 to 2,000 m, fish assemblages were relatively uniform among all stations and were dominated by E. antarctica (juvenile–subadult), Cyclothone microdon, and Bathylagus antarcticus. Cluster analysis revealed three epipelagic communities related to water temperature and salinity. An ontogenetic habitat shift to deeper layers was apparent for E. antarctica, N. coatsi, and B. antarcticus. Preferences for warm waters were observed in E. antarctica (larvae) and N. coatsi (preflexion to flexion larvae), although they were distributed across a broad range of temperature and salinity in epipelagic zones.     

Siliceous scales of filose-amoebae (Pompholyxophryidae,Rotosphaerida) from deep Southern Ocean sediments,including first records for the Southern Hemisphere

The world of protists remains largely unexplored. A thorough electron-microscopic investigation of a few microlitres of deep-sea sediment from 2,964 m water depth near the South Sandwich Islands (Southern Ocean) revealed siliceous scales of filose-amoeba protist species, two of which have not been reported previously from Antarctica or from elsewhere in the Southern Hemisphere. However, all the species are known from other oceans and, in one case, from freshwater habitats. The Antarctic protistan scales belong to four species of filose amoebae: Pinaciophora fluviatilis Greef 1869, Pinaciophora denticulata Thomsen 1978, Pinaciophora multicosta Thomsen 1978 and Rabdiaster reticulata (Thomsen 1979) Mikrjukov 1999 nov. comb. Our study shows that (1) none of the species has been recorded from the Australasian biogeograpical region, (2) Pinaciophora multicosta and Rabdiaster reticulata are new records for the Southern Ocean and for the Southern Hemisphere as a whole, (3) prior to this investigation, Pinaciophora multicosta had been reported once only, from the Baltic Sea (Europe). These results highlight the problem of undersampling in the study of the global distribution of protists.     

Reassessment of the isopod crustacean Aega deshaysiana (Milne Edwards, 1840) (Cymothoida: Aegidae): a world-wide complex of 21 species

Aega deshaysiana (Milne Edwards, 1840) and A. antillensis Schioedte & Meinert, 1879, have long been confounded, with all records eventually becoming regarded as belonging to one globally distributed species, namely A. deshaysiana. These two species are redescribed and differentiated, with A. schioedteana Bovallius, 1885 remaining in synonymy with A. deshaysiana. Aega deshaysiana occurs only in the eastern North Atlantic and Mediterranean, while A. antillensis is known only from the Caribbean and Gulf of Mexico. A further two named species are redescribed: A. excisa Richardson, 1910, previously placed in synonymy with A. deshaysiana, and A. magnifica (Dana, 1852). A neotype is designated for A. magnifica. This ‘complex’ or group of Aega species is distinguished from the others by their large eyes, which are usually medially united and occupy most of the head, their large adult size (20–60 mm), a posteriorly acute and defined pleotelson apex, and the uropod rami not extending posteriorly beyond the pleotelson, with exopod held at an oblique angle to the endopod and deeply notched endopod lateral margin. The group is not necessarily monophyletic, as there is a gradation in the depth of the uropod notch from deep to scarcely evident, and in eye size from entirely occupying the head to just separate (though the eyes are always large). Twelve new species in the group are described. All species are considered to be micropredators of fishes and elasmobranches, although prey records are few and unreliable owing to the readiness of these isopods to detach. Species of the group have been recorded from depths varying between 10 m and 600 m and occasionally deeper. Several have extensive distributions ranging from the Southern Ocean to tropical waters. The group is represented in all oceans. © 2004 The Linnean Society of London, Zoological Journal of the Linnean Society, 2004, 142 , 135–232.     

Results of satellite tagging of Atlantic bluefin tuna, <Emphasis Type="Italic">Thunnus thynnus</Emphasis>, off the coast of Ireland

Pop-up satellite archival tags were attached to six Atlantic bluefin tuna (Thunnus thynnus) off the west coast of Ireland in autumn 2003 and 2004. The satellite tags measured pressure, ambient temperature and light for the term of deployment. Radio pop-up satellite endpoint positions, light and sea surface temperature estimations of geolocation indicate that two fish tagged minutes apart off the coast of County Donegal, migrated to the eastern and western Atlantic Ocean over the following 8 months. The two fish were 5218 km apart at the termination of the experiment. After tagging in September and popping up the following March and April, one fish had traveled to the western Atlantic while the other was located in the waters off the southwest coast of Portugal. A third fish tagged off the coast of County Donegal in October 2004 moved into the Mediterranean Sea and was caught by a fishing vessel southeast of Malta on 11 June 2005. The results link bluefin tuna feeding on European foraging grounds with known eastern breeding regions and western Atlantic waters.