The free-living nematodes of a temperate, high energy, sandy beach: faunalcomposition and variation over space and time

Free-living marine nematodes were sampled extensively over a 2-year period on a long sandy beach exposed to high-energy ocean swells in southeastern A ustralia. Samples were taken in summer and winter at different tide levels on the beach, and at different positions along the beach. A total of 58 spe cies from 48 genera were found, many as yet known only from Australia. Pred ators and particle feeders were always the most abundant feeding guilds, bu t species composition varied markedly between samples. The variation in abu ndance and composition of the fauna was analysed statistically. There were considerable differences between high-, mid- and low-tide faunas along a si ngle transect of the beach which persisted for 24 h with calm seas, but not over several months. There were also considerable differences between loca tions along the beach. It appears that hydrodynamic forces constantly redis tribute the fauna, introducing a large probabilistic element into patterns of total nematode abundance and faunal composition.