Aspects morphologiques et dynamiques de constructions de l'Annelide polychete Sabellaria alveolata (Linne).

The study is illustrated by photographs, consideration being given to the stages in the establishment of colonies on shells and pebbles. Stages of implantation and the types of construction thereby formed are described, and the process of growth in height examined. Implantation of other individuals, hydrodynamics, tube density, temperature and age or average sizes of the population are thought to influence this growth. The surface area occupied by the constructions may be extended by colonization of pebby or shelly areas or by transportation of parts broken away. Destruction and death of the constructions may be extended by colonization of pebby or shelly areas the constructions is described. It was found that the reefs underwent a particular mode of implantation starting on small hard surfaces, and that increase in colonies by break-aways could be stabilized by the polychaete Lanice conchilega (Pallas). `Cauliflower' or `mushroom' constructions were the most common, 30-40 cm high, but barriers were also found, the end product being an undulating platform. Growth rates were variable, and one means of growth control was probably accumulation of waste at tube mouths.