Avoidance of dried biofilms on slate and algal surfaces by certain spirorbid and bryozoan larvae

The effect of aerial drying of biofilmed surfaces to simulate a tidal emers ion upon the settlement preferences of spirorbid and bryozoan larvae was in vestigated using choice experiments with still water conditions carried out in the laboratory Aerial drying of biofilmed slates and pieces of Fucus se rratus for 1 h at 20 degreesC negated their usual settlement-inducing prope rties to Larvae of Spirorbis spirobis S. tridentatus and Flustrellidra hisp ida. Such larval settlement preference may contribute to observed variation s in the natural distribution of these species in the intertidal.