Dominant zooplankton species and microelements in plankton obtained from White Sea surface waters

Despite the fact that plankton plays an important role in biogeochemical processes in oceans, data on its elemental composition, particularly in shelf seas of the Arctic Ocean, have thus far been insufficient. This communication, which is devoted to a comparative analysis of the elemental composition of plankton and bottom sediments in the White Sea, is part of the comprehensive investigation of the region that is occurring in line with the International Project ''Land-Ocean Interaction in the Russian Arctic'' (LOIRA).

Zooplankton abundance from METEOR cruise M87/1 in April 2012

Zooplankton samples were taken in five depth strata using a Multinet type Midi, with 50 µm nets. The samples were taken during the second leg only, three times at station 1, two times at station 2 and once at station 3. Zooplankton were identified to species / genus and life-stage, and at least 300 individuals were counted per sample. 10 individuals of each stage / species were measured and the numbers of eggs counted.

Species abundance and water and sediment characteristics for three ANDEEP stations on Maud Rise and the Weddell Sea

The benthic fauna was investigated during the expedition ANT-XXIV/2 (2007/08) in relation to oceanographic features, biogeochemical properties and sediment characteristics, as well as the benthic, pelagic and air-breathing fauna. The results document that Maud Rise (MR) differs distinctly from surrounding deep-sea basins investigated during previous Southern Ocean expeditions (ANDEEP 2002, 2005). Considering all taxa, the overall similarity between MR and adjacent stations was low (~20% Bray-Curtis-Similarity), and analyses of single taxa show obvious differences in species composition, abundances and densities. The composition and diversity of bivalves of MR are characterised by extremely high abundances of three species, especially the small sized Vesicomya spp. Exceptionally high gastropod abundance at MR is due to the single species Onoba subantarctica wilkesiana, a small brooder that may prey upon abundant benthic foraminiferas. The abundance and diversity of isopods also show that one family, Haplomunnidae, occurs with a surprisingly high number of individuals at MR while this family was not found at any of the 40 bathyal and abyssal ANDEEP stations. Similarly, polychaetes, especially the tube-dwelling, suspension-feeder fraction, are represented by species not found at the comparison stations. Sponges comprise almost exclusively small specimens in relatively high numbers, especially a few species of Polymastiidae. Water-column sampling from the surface to the seafloor, including observations of top predators, indicate the existence of a prospering pelagic food web. Local concentrations of top predators and zooplankton are associated with a rich ice-edge bloom located over the northern slope of MR. There the sea ice melts, which is probably accelerated by the advection of warm water at intermediate depth. Over the southern slope, high concentrations of Antarctic krill (Euphausia superba) occur under dense sea ice and attract Antarctic Minke Whales (Balaenoptera bonaerensis) and several seabird species. These findings suggest that biological prosperity over MR is related to both oceanographic and sea-ice processes. Downward transport of the organic matter produced in the pelagic realm may be more constant than elsewhere due to low lateral drift over MR.