A method for efficient extraction of rotifers (Rotifera) from soils

Rotifers are a group of soil animals which are not commonly quantified. The most recent data originated from soil studies focussed on nematodes and various modifications of the Baermann funnel, which is not suitable for rotifers. The present study developed a method for quantitative extraction of rotifers, which gives representative results describing rotifer populations and facilitates subsequent identification to the species level. The LC extractor recovered rotifer numbers that were two orders of magnitude higher than what was extracted from the Baermann funnel. The method involves spreading a soil sample on a plastic sieve and uses a very thin layer of cellulose submerged in distilled water in a Petri dish. The Petri dish is situated on a cooled panel and light from the top by fluorescent lamps. The temperature of the base panel which gave the best extraction results was determined experimentally to be 5 °C. Rotifers were not able to withstand any heating from the top, which drastically reduced extraction results.