Limosina brachystoma can be reared even when the food and substratum (dry leaves of Urtica or almost any other plant) are moistened with 15‰ NaCl p.a. or with 15‰ NaCl plus KCl. Orchestia lives about three weeks if kept on a substratum moistened with a solution of 15‰ NaCl (Food: Fucus).H₂SO₄, on the other hand, is fatal especially, for Orchestia.Burning oil gives off pollutants into the surrounding water. These pollutants are fatal for all the animals studied even at very low concentrations. But in air (not in water) these pollutants disappear within one week and the substratum may be colonized again.Crude oil which has floated in the sea for a long time is not any longer poisonous to the animals studied. It does not hinder rapid propagation of all species Larvae of the flies and - to a lesser extent - of the amphipodes rummage in their substratum and disperse a big piece of old crude oil into fine parts throughout the petri dish.