ZOARIAL FORMS IN THE DEVELOPMENT OF A BRYOZOAN COMMUNITY

Abstract

The dynamics of the relations between different zoarial forms of cheilostome bryozoans, during the development of a community on artificial substrates, have been studied along an infralittoral cliff of the northwestem Mediterranean Sea. Membraniporiform bryozoans (thick membraniporiform and thin membraniporiform zoarial types) prevail during the first stages of colonization. Later, at shallow depth, erect flexible forms (tuft-like zoarial type) tend to increase prevailing over the encrusting ones and, at greater depth, membraniporiform colonies continue to play a major role. The studied zoarial types show differences both in their ability to settle and to grow on bare and smooth surfaces and on substrate occupied by other organisms, and also to adjust to modifications of the substrate through time. The variations in the relative abundance of different zoarial forms correspond to changes in the availability of primary space and to new ecological conditions close to the substrate surface.