Composition and distribution of the peracarid crustacean fauna along a latitudinal transect off Victoria Land (Ross Sea, Antarctica) with special emphasis on the Cumacea

The following study was the first to describe composition and structure of the peracarid fauna systematically along a latitudinal transect off Victoria Land (Ross Sea, Antarctica). During the 19th Antarctic expedition of the Italian research vessel “Italica” in February 2004, macrobenthic samples were collected by means of a Rauschert dredge with a mesh size of 500 m at depths between 85 and 515 m. The composition of peracarid crustaceans, especially Cumacea was investigated. Peracarida contributed 63% to the total abundance of the fauna. The peracarid samples were dominated by amphipods (66%), whereas cumaceans were represented with 7%. Previously, only 13 cumacean species were known, now the number of species recorded from the Ross Sea increased to 34. Thus, the cumacean fauna of the Ross Sea, which was regarded as the poorest in terms of species richness, has to be considered as equivalent to that of other high Antarctic areas. Most important cumacean families concerning abundance and species richness were Leuconidae, Nannastacidae, and Diastylidae. Cumacean diversity was lowest at the northernmost area (Cape Adare). At the area off Coulman Island, which is characterized by muddy sediment, diversity was highest. Diversity and species number were higher at the deeper stations and abundance increased with latitude. A review of the bathymetric distribution of the Cumacea from the Ross Sea reveals that most species distribute across the Antarctic continental shelf and slope. So far, only few deep-sea records justify the assumption of a shallow-water–deep-sea relationship in some species of Ross Sea Cumacea, which is discussed from an evolutionary point of view

Quantitative analysis of soft-bottom molluscs in the Bellingshausen Sea and around Peter I Island

Macrobenthic soft-bottom molluscs were sampled in 30 stations located in the Bellingshausen Sea at depths ranging from 90 to 3304 m. The samples were collected using a quantitative grab box-corer during the cruises BENTART 03, from 24 January to 3 March 2003, and BENTART 06, from 2 January to 16 February 2006. Molluscs represent 1074 specimens belonging to 62 species of Polyplacophora, Gastropoda, Bivalvia and Scaphopoda. The bivalve Cyamiocardium denticulatum was the most abundant species (448 specimens). The abundance per station varied between 1 and 446 specimens. The Shannon–Wiener diversity index ranged between one specimen and 2.36, the Pielou evenness index ranged between 0.00 and 1 and species richness ranged from 1 to 14 species. Diversity showed great variations at different stations. After multivariate analysis (cluster analysis and nonmetrical multidimensional scaling) based on Bray–Curtis similarities, we were able to separate two principal clusters. The first cluster groups together species from shallower bottoms near Peter I Island and the Antarctic Peninsula, and the second cluster groups together species from deeper bottoms in the Bellingshausen Sea. The combination of environmental variables with the highest correlations with faunistic data was that of depth and coarse sand at the surface.Publicado

Demography of krill in the Elephant Island area during summer 2001 and its significance for stock recruitment

A net sampling survey was carried out for krill in an established standard station grid around Elephant Island during 27 January to 4 February 2001. Results show a spatial separation of the juvenile and the spawning stock. The station grid was extended to the south, where a large proportion of small size classes, one year old juvenile krill was found. Krill density was significantly higher than during the past years (between 198 and 230 krill 1000 m-3 , i.e. between 40 and 46 m-2 or 11.3 g m-2). The proportional recruitment index for the entire survey area for the 1999/2000 year class was R1 = 0.573, and the absolute index was RI1 = 131.4 * 1000 m-3 , which is among the highest values for the past 20 years. The high krill abundance and the high recruitment index reflect the end of a succession of years with poor recruitment success. The maturation index (G, according to gravid stages), which is discussed as an indicator for a successful spawning season, was G = 0.99, indicating an early initiation of the spawning season. This is thought to be the first step for a successful spawning event and a later potential recruitment success of the 2000/01 year-class. The spatial extent of the station grid is discussed in the light of a representative coverage of the stock and the estimated recruitment inde

Large scale patterns in Antarctic biomass and production

A total of 869 quantitative benthos samples (corers and grabs) were collected at 203 stations in the Weddell Sea and Peninsula regions by German expeditions between 1984 and 2000. Spatial and taxonomic distribution patterns of macrobenthic production and biomass are analysed based on 35 major taxonomic groups