Artificial oases in a lacustrine desert.

1. Aspects of colonization by freshwater invertebrates on artificial substrata (macrophyte models) placed in the benthos of a eutrophic lake were studied. 2. Colonization was rapid, with equilibrium occuring at about 35 days. The colonization rate curve decreased with time but extinction rate remained constant. 3. Predators formed 22-32% of the fauna at equilibrium. 4. Area and distance accounted for 92% of the variation in species richness; 69% of the variation was due to area alone. 5. The faunal coefficients z were higher than expected and may be due to competitive interactions in simple habitats.