SALINITY RESISTANCE AND SALINITY PREFERENCE OF TWO OLIGOCHAETES AKTEDRILUS MONOSPERMATECUS KN5LLNER AND MARIONINA PRECLITELLOCHAETA N.SP. FROM THE INTERSTITIAL FAUNA OF MARINE SANDY BEACHES.

1. Some objections to the usual way of expressing the total amounts of salt in the littoral subsoil water as S% are made and measurement of the electrical conductivity is recommended. 2. It is pointed out that the conception of euryhalinity does not exclude a preference for a certain part of the salinity scale which is the theme of this paper. 3. A new alternative chamber for salinity is described. 4. The resistance of Akiedrilus monospermazecus from 6 S% and Marionina preclitellochaeta from 2 S%, was measured, the animals tolerated 1.25-20 S% resp. 2.5-10 S% during the time of experiment, 5 respectively 6 days. 5. The salinity preference of Aktedrilus monospermazecus from 6 S% in the field was found to be 2.5-5 S% while Marionina preclitellochaeta from 0 S%, preferred 0.2-0.3 S%. It is clear that the animals actively choose distinct salinities, at least in the laboratory. 6. The concept of stable preferences is also discussed. Experiments with Akiedrilus inonospermatecus showed that the preference for 5 S% remained even after eight days at 20 S%. [ABSTRACT FROM AUTHOR]