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Kersken D.,University of Rostock | Gocke C.,Forschungsinstitut und Naturmuseum Senckenberg | Brandt A.,Zoological Institute and Zoological Museum | Lejzerowicz F.,University of Geneva | And 4 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography

Due to their high abundance and large body size sponges have a central position in Antarctic zoobenthos, where they form the most extensive sponge grounds of the world. Though research on Antarctic benthos communities is quite established, research on sponge-associated infauna communities is scarce. We analyzed associated infauna of fifteen individuals of the sponge species Mycale (Oxymycale) acerata Kirkpatrick, 1907 (Demospongiae: Mycalina), Rossella antarctica Carter, 1872 and R. racovitzae Topsent, 1901 (both Hexactinellida: Lyssacinosida). Samples were collected from the deep Ekström Shelf at 602. m in the South-Eastern Weddell Sea, Antarctica, during the ANT XXIV-2 (SYSTCO I) expedition of RV Polarstern. The number of species, α- and β-diversity and the significantly different species composition of infauna communities related to sponge species were calculated, the latter via cluster analysis. The sponge-associated infauna consisted of five phyla: Foraminifera, Nematoda, Polychaeta, Mollusca and Arthropoda. In total 11,463 infaunal specimens were extracted and we found at least 76 associated species. Highest values of α-diversity were calculated for a sample of R. antarctica with a Shannon-Index of 1.84 and Simpson-Index of 0.72 respectively. Our results of the cluster-analysis show significant differences between infauna communities and a unique species composition for single sponge species. Polychaetes of the genus Syllis Lamarck, 1818 were numerous in M. acerata and genera like Pionosyllis Malmgren, 1867 and Cirratulus Lamarck, 1801 were numerous in R. antarctica. Individuals of the amphipod species Seba cf. dubia Schellenberg, 1926 were often found in R. antarctica and R. racovitzae while Colomastix fissilingua Schellenberg, 1926 was frequent in samples of M. acerata. Molluscs were present in M. acerata and R. antarctica but absent in R. racovitzae. © 2014 Elsevier Ltd. Source

Brandt A.,Zoological Institute and Zoological Museum | Vanreusel A.,Ghent University | Bracher A.,Alfred Wegener Institute for Polar and Marine Research | Jule Marie Hoppe C.,Alfred Wegener Institute for Polar and Marine Research | And 4 more authors.
Deep-Sea Research Part II: Topical Studies in Oceanography

In austral summer 2012, during the expedition ANT-XXVIII/3 on board RV Polarstern, two sites were sampled 1600km apart in the South Polar Front area (52°S) at the boundary of different productivity regimes for meio- and macrobenthos using a multiple-corer and an epibenthic sledge, respectively. Patterns in density and abundance data were compared between different size classes of the benthos and interpreted in relation to surface primary productivity data and sediment oxygen consumption. We tested the hypothesis that long-term satellite-derived surface phytoplankton biomass, in situ real time biomass, and productivity measurements at the surface and throughout the euphotic zone are reflected in abyssal benthos densities, abundances and activity. Specifically, we investigated the effect of boundary conditions for lower and higher surface productivity. Surface and integrated to 100m depth biomass and primary productivity measurements vary stations, with the lowest values at station 85 (0.083mgChl-am-3 at surface, 9mgChl-am-2 and 161mgCm-2 d-1- integrated over the first 100m depth), and the highest values at station 86 (2.231mgChl-am-3 at surface, 180mgChl-am-2 and 2587mgCm-2d-1 integrated over first 100m depth). Total meiofaunal densities varied between 102 and 335individuals/10cm2. Densities were the highest at station 86-30 (335 individuals) and lowest at station 81-13 (102 individuals). Total macrofaunal densities (individuals/1000m2) varied between 26 individuals at station 81-17 and 194 individuals at station 86-24. However, three EBS hauls were taken at station 86 with a minimum of 80 and a maximum of 194 individuals. Sediment oxygen consumption did not vary significantly between stations from east to west. Bentho-pelagic coupling of meio- and macrobenthic communities could not be observed in the South Polar Front at the boundary conditions from low to high surface productivity between stations 81 and 86. © 2014 Elsevier Ltd. Source

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