Macrobenthic Mollusca of the Prince Gustav Channel, Eastern Antarctic Peninsula: An Area Undergoing Colonisation

In 2018 RRS James Clark Ross investigated the marine benthic biodiversity of the Prince Gustav Channel area which separates the eastern coast of the Antarctic Peninsula from James Ross Island. The southern end of this channel had been covered by the Prince Gustav Ice Shelf until its collapse in 1995. Benthic samples were collected by an epibenthic sledge at six stations (200–1,200 m depth) in the channel and adjacent Duse Bay. In total 20,307 live collected mollusc specimens belonging to 50 species and 4 classes (Solenogastres, Bivalvia, Gastropoda, and Scaphopoda) were identified. The area may be characterised by it’s low species richness (ranging from 7 to 39 species per station) but high abundances (specifically of the Scaphopods with 11,331 specimens). The functional traits of the community were dominated by motile development and mobility type. Assemblage analyses of the molluscan species abundances within the Prince Gustav Channel stations sit distinct, with no pattern by depth or location. However, when bivalve assemblages were analysed with reference to the wider Weddell Gyre region (15 stations from 300 to 2,000 m depth), the Prince Gustav Channel sits distinct from the other Weddell Gyre stations with a higher dissimilarity between the deeper or more geographically distant areas. The Prince Gustav Channel is undergoing colonisation following the recent ice shelf collapse. With many Antarctic ice shelves threatened under climate warming, this area, with future monitoring, may serve as a case study of benthic faunal succession.

The Discovery and Preliminary Geological and Faunal Descriptions of Three New Steinahóll Vent Sites, Reykjanes Ridge, Iceland

During RV MS Merian expedition MSM75, an international, multidisciplinary team explored the Reykjanes Ridge from June to August 2018. The first area of study, Steinahóll (150–350 m depth), was chosen based on previous seismic data indicating hydrothermal activity. The sampling strategy included ship- and AUV-mounted multibeam surveys, Remotely Operated Vehicle (ROV), Epibenthic Sledge (EBS), and van Veen grab (vV) deployments. Upon returning to Steinahóll during the final days of MSM75, hydrothermal vent sites were discovered using the ROV Phoca (Kiel, GEOMAR). Here we describe and name three new, distinct hydrothermal vent site vulnerable marine ecosystems (VMEs); Hafgufa, Stökkull, Lyngbakr. The hydrothermal vent sites consisted of multiple anhydrite chimneys with large quantities of bacterial mats visible. The largest of the three sites (Hafgufa) was mapped, and reconstructed in 3D. In total 23,310 individual biological specimens were sampled comprising 41 higher taxa. Unique fauna located in the hydrothermally venting areas included two putative new species of harpacticoid copepod (Tisbe sp. nov. and Amphiascus sp. nov.), as well as the sponge Lycopodina cupressiformis (Carter, 1874). Capitellidae Grube, 1862 and Dorvilleidae Chamberlin, 1919 families dominated hydrothermally influenced samples for polychaetes. Around the hydrothermally influenced sites we observed a notable lack of megafauna, with only a few species being present. While we observed hydrothermal associations, the overall species composition is very similar to that seen at other shallow water vent sites in the north of Iceland, such as the Mohns Ridge vent fields, particularly with peracarid crustaceans. We therefore conclude the community overall reflects the usual “background” fauna of Iceland rather than consisting of “vent endemic” communities as is observed in deeper vent systems, with a few opportunistic species capable of utilizing this specialist environment.

Six new species of Macellicephala (Annelida: Polynoidae) from the Southern Ocean and south Atlantic with re-description of type species

Increased sampling efforts in unexplored regions of the Southern Ocean (including depths >500 m) combined with the use of an epibenthic sledge resulted in a large collection of mobile, scale-bearing worms from the family Polynoidae Kinberg, 1856. The greatest taxonomic novelty was found in the genus Macellicephala McIntosh, 1885, the type genus of the exclusively deep-sea polynoid sub-family Macellicephalinae Hartmann-Schröder, 1971. Recently collected material from the Amundsen Sea led to discovery of four new species based on morphology and COI, 16S and 18S genes—Macellicephala gloveri sp. nov., M. linseae sp. nov., M. patersoni sp. nov. and M. brenesorum sp. nov. The holotype of type taxon Macellicephala mirabilis McIntosh, 1885 as well as historic material of Macellicephala collected from the Southern Ocean enabled comparison with the modern material. As a result, Macellicephala mirabilis is re-defined, and two new species, M. monroi sp. nov. and M. macintoshi sp. nov., are erected from the historic material previously ascribed to M. mirabilis. Additionally, DNA-suitable specimens assigned to M. monroi sp. nov. were collected from the Scotia Sea. Genetic data enabled the first test of the monophyly of Macellicephala. Based on current taxa coverage, these taxa form a well-supported monophyletic group as recovered by Bayesian and Maximum Likelihood analyses of our combined genetic dataset. In addition, the analysis shows strong support of a clade comprising Macellicephala and other exclusively deep-sea groups (including cave-dwelling taxa).

Two new species of the Suborder Senticaudata (Crustacea: Amphipoda) from the upper continental slope off Galicia (NW Iberian Peninsula)

Two new species of the Suborder Senticaudata (Corophiidae and Photidae) are described. They were collected during the expeditions “DIVA ARTABRIA I” in 2003 and “A Selva” in 2008, off the Galician coast (NW Iberian Peninsula). Samples were taken on hard bottoms between 800 and 1000 m deep using different gears (an epibenthic sledge an Agassiz trawl and a naturalist dredge). The corophiid Pareurystheus vitucoi sp. nov. is a blind species that can be easily distinguished from the other known genus species by the size and shape of pereopod 5. The photid Photis guerrai sp. nov is also a blind species, characterized by the presence of an anterodistal lobe on the basis of gnathopod 2. A key to the genera of Protomedeiinae is also included, as well as keys for the species of the genus Pareurystheus and the Atlantic and Mediterranean species of the genus Photis.

Deep-sea Benthic Ostracodes from Multiple Core and Epibenthic Sledge Samples in Icelandic Waters

Deep-sea benthic Ostracoda (Crustacea) in Icelandic waters are poorly known. Here we report deep-sea ostracode assemblages from the multiple core (MUC) and the epibenthic sledge (EBS) samples collected from Icelandic waters by the first cruise of the IceAGE (Icelandic Marine Animals: Genetics and Ecology) project. Samples from shelf-edge and lower-bathyal working areas are examined. The results show (1) distinct MUC and EBS faunas due to the large difference in mesh size of MUC and EBS; and (2) distinct shelf-edge and lower-bathyal ostracode faunas. Such remarkable faunal turnover from shelf to bathyal depths is similar to the faunal turnovers reported from depth transects in the adjacent regions of the western North Atlantic Ocean, the Greenland Sea, and the North Sea, but, at the same time, there are certain differences in the faunal composition between the Icelandic waters and these adjacent regions. In addition, we illustrate many Icelandic deep-sea ostracode species with high-resolution scanning electron microscopy and composite all-in-focus stereomicroscopic images for the first time. These results provide important basic information on deep-sea ostracode research and biogeography of this important region connecting North Atlantic proper and Nordic Seas.

Tanaidacea of the Amundsen and Scotia seas: an unexplored diversity

The Scotia Arc and Amundsen Sea are contrasting regions within West Antarctica. The Scotia Sea shelf is well studied and central to the origin and diversity of the Southern Ocean benthic fauna, whilst the shelf of Amundsen Sea is one of the least studied shelf areas in the world; a ‘white spot’ on the map of benthic research. Here we report on the tanaidaceans collected using an epibenthic sledge on two expeditions, BIOPEARL 1 and 2, of the RRSJames Clark Rossin 2006 and 2008, respectively. This study represents the first analysis of the tanaidacean fauna of those two basins. Thirty-seven species were found in the Amundsen Sea from 500–1500 m depth and 51 species were found at depths ranging from 200–1600 m in the Scotia Sea. In the Scotia Sea, many species were unique to each of the study sites which may be evidence of allopatric speciation episodes. Site specificity was especially evident forTyphlotanaisandPseudotanais. Only three species were common to both basins. Around 90% of the species were previously undescribed. Our findings increase the number of the tanaidaceans known in the Southern Ocean by 50%.