Epibenthic macrofauna abundance during RSS James Clark Ross cruise JR144, South Sandwich arc

The remote South Sandwich arc is an archipelago of small volcanic islands and seamounts entirely surrounded by deep water and about 600 km away from the closest island, South Georgia. As some of the youngest islands (< 5 m.y.) in the Southern Ocean they are ideal for studying colonization processes of the seabed by benthic fauna, but are rarely investigated because of remoteness and extreme weather. The current study attempted to quantify the richness and abundance of the epibenthic macrofauna around the Southern Thule group by taking five epibenthic sledge samples along a depth transect including three shelf (one at 300 m and two at 500 m) and two slope stations (1000 and 1500 m). Our aim was to investigate higher taxon richness and community composition in an isolated Antarctic locality, since recent volcanic eruptions between 1964 and 1997. We examined patterns across all epibenthic macrofauna at phylum and class levels, and investigated trends in some model groups of crustaceans to order and family level. We found that abundance was highest in the shallowest sample and decreased with depth. Shelf samples (300 and 500 m) were dominated by molluscs and malacostracans while at the deeper stations (1000 and 1500 m) nematodes were the most abundant taxon. Surprisingly, the shallow shelf was dominated by animals with restricted dispersal abilities, such as direct developing brooders (malacostracans) or those with lecithotrophic larvae (bivalves of the genus Yoldiella, most bryozoan species). Despite Southern Thule's geological youth, recent eruptions, and its remoteness the shallow shelf was rich in higher taxa (phyla/classes) as well as orders and families of our model groups. Future work at higher taxonomic resolution (species level) should greatly increase understanding of how life has reached and established on these young and highly disturbed seabeds.

Abundance of mesozooplankton during the long-tern mesozooplankton analysis in Sevastopol Bay from 1976 to 2003

The present dataset includes results of analysis of 227 zooplankton samples taken in and off the Sevastopol Bay in the Black Sea in 1976, 1979-1980, 1989-1990, 1995-1996 and 2002-2003. Exact coordinates for stations 1, 4, 5 and 6 are unknown and were calculated using Google-earth program. Data on Ctenophora Mnemiopsis leidyi and Beroe ovata are not included. Juday net: Vertical tows of a Juday net, with mouth area 0.1 m**2, mesh size 150µm. Tows were performed at layers. Towing speed: about 0.5 m/s. Samples were preserved by a 4% formaldehyde sea water buffered solution. Sampling volume was estimated by multiplying the mouth area with the wire length. The collected material was analysed using the method of portions (Yashnov, 1939). Samples were brought to volume of 50 - 100 ml depending upon zooplankton density and mixed intensively until all organisms were distributed randomly in the sample volume. After that 1 ml of sample was taken by calibrated Stempel-pipette. This operation was produced twice. If divergence between two examined subsamples was more than 30% one more subsample was examined. Large (> 1 mm body length) and not abundant species were calculated in 1/2, 1/4, 1/8, 1/16 or 1/32 part of sample. Counting and measuring of organisms were made in the Bogorov chamber under the stereomicroscope to the lowest taxon possible. Number of organisms per sample was calculated as simple average of two subsamples meanings multiplied on subsample volume. Total abundance of mesozooplankton was calculated as sum of taxon-specific abundances and total abundance of Copepods was calculated as sum of copepods taxon-specific abundances.