Meiofauna communities along an abyssal depth gradient in the Drake Passage

Abstract

Abstract Meiofauna standing stocks and community structure are reported for the first time for abyssal soft-sediment samples in Antarctic waters. At seven stations within a depth range of 2274–5194 m a total of 128 sediment cores were retrieved with a multiple corer (MUC) on board of the R.V. Polarstern during the ANDEEP-1 cruise (ANT XIX/3). The metazoan meiofauna (defined by a lower size limit of 40 μm) was identified and counted, and one core per station was preserved for CPE, C/N, TOM and grain size analyses. Meiofauna densities are in the range of 2731 Ind./10 cm2 at 2290 m depth and 75 Ind./10 cm2 at 3597 m depth, with nematodes being the dominant group at all stations. Nematodes account for 84–94% followed by copepods with 2–8% of the total meiofauna. Other frequent taxa found at each station are kinorhynchs, loriciferans, tantulocarids, ostracods and tardigrades. There is a general tendency of decreasing abundances of metazoan meiofauna with increasing depth, but not all higher level taxa displayed this pattern. In addition, a tendency of decreasing higher taxon density with increasing depth was observed. Standing stocks are higher than the average found at similar depths in other oceans.