POPULATION-DYNAMICS AND OVERGROWTH OF THE SEA FAN EUNICELLA-CAVOLINI (COELENTERATA, OCTOCORALLIA)

The population dynamics of Eunicella cavolini Koch was investigated fr om 1989-91 at three study sites in the Bay of Calvi (Corsica, France). Population density was highest in the channel (149-180 colonies m(-2) ), intermediate at the wall (54-66 colonies m(-2)) and lowest at the b oulders (15-19 colonies m(-2)). Mortality, expressed as percentage of colonies that died within 1 year of investigation, did not differ betw een the study sites and showed large variability (8.3-26.7%). Expresse d as percentage of new colonies on total colony numbers, recruitment w as highest in the channel (11.7-20.1%), intermediate at the wall (7.4- 12.0%) and lowest at the boulders (0-8.3%). A growth formula for E. ca volini developed in an earlier study (Velimirov, 1975) was shown to be suitable for the investigated study sites. The estimated maximum age was 21 years. Age frequency distribution did not vary strongly between subsequent years during the 3-year investigation. However, the age st ructure differed strongly between study sites. Overgrowth of colonies was highest at the boulders, intermediate at the wall and lowest in th e channel. Overgrowth increased with colony age until the age of 4 yea rs. Mortality of E. cavolini is mainly due to detachment and overgrowt h. (C) 1996 Academic Press Limited