414 resultados para Appendicularia
Resumo:
The dataset is composed of 50 years of approximately monthly mesozooplankton sampling at station Stoncica. The volume of filtered water was estimated assuming 70% efficiency of the Hensen 330 micrometer mesh size net according to Laevastu (1958). Subsamples amounting to 1/20 of the catch were counted for the most representative groups. The whole catch was examined for rare species.The results in the datatables are recalculated to (#/m**3).
Resumo:
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.
Resumo:
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.
Resumo:
Size-, species- and age composition of zooplankton was studied in the ice-covered Chupa Inlet (White Sea, Kandalksha Bay) in early April 2002. The species composition of zooplankton was poor and typical for the end of the winter season, and abundance and biomass were considerably lower than in summer. In terms of biomass two species of copepods (Calanus glacialis and Pseudocalanus minutus) prevailed. Both species were already feeding on ice algae available and began to reproduce. Such early reproduction of Calanus glacialis was noted in the White Sea for the first time. Obtained results show that secondary production in the White Sea starts well before thawing of the ice cover.