MEIOFAUNA EXTRACTION EFFICIENCY BY A MODIFIED OOSTENBRINK APPARATUS

A semi-automatic method for the extraction of soil nematodes (Oostenbrink, 1960) was modified for the separation of psammolittorine meiofauna from routine samples collected during a marine pollution monitoring programme. This method was compared with Elmgren's (1976) decantation technique. The two procedures used did not differ significantly in terms of extraction efficiency. They were applied to samples containing nematodes and harpacticoid copepods of known numbers in medium-fine and coarse sand, using fresh water and sea water as extraction media. Losses within the apparatus were found to be negligible. By 2×2×2 factorial analysis, which was used to separate the effects of methods and treatments, nonsignificant differences for nematode recovery were obtained; harpacticoids, however, were less efficiently recovered by the Oostenbrink method using sea water. The Oostenbrink flotation method took 9 to 12 min per sample, caused no or only little damage to the fauna and gave consistent results with different operators. © 1979 Biologischen Anstalt Helgoland.