A rapid method of extracting meiobenthic nematodes and copepods from mud and detritus

The extraction of nematodes and harpacticoid copepods from muddy sediments or sediments containing a large amount of organic detritus can be achieved through a series of centrifugations or the material in a saccharose solution of at least 900 g/l. The number of individuals appearing in the supernatant after each centrifugation forms a geometric series, with a ratio which is dependent on the amount of material, the concentration of the saccharose solution, and the acceleration of the centrifuge. Knowledge of this ratio allows an estimation of density after only one centrifugation. More than 90% of the animals present in the sample can be extracted after only two centrifugations.