Patch-dynamics and population structure of nematodes and tardigrades on Antarctic nunataks

Assemblages of hydrophilic microfauna (nematodes, rotifers and tardigrades) in moss-cushions from four ice-free mountain peaks (nunataks) in East Antarctica were studied. Nematodes occurred in 64%, tardigrades in 32% and rotifers in 82% of 91 samples taken in moss. No animals were found in 8% of the samples. The differences in occurrence of animals among cushions are probably due to stochastic colonization processes. The structure of nematode populations indicates that they exhibit different developmental stages in the various samples. Competition or predation appears to influence the abundances of coexisting populations. Predation by tardigrades on rotifers might occur, while the nematodes appear to be competitors rather than preys of the tardigrades.