[Growth and Age Determination in the Sea Fan Eunicella cavolinii]

Growth of the sea fan Eunicella cavolinii was studied on the south coast of Filicudi, an island north-west of Sicily. Colonies, ranging from 1 to 100 cm in total length were observed for 2 years and 10 series of measurements taken during this period, including all seasons of the year. Each branch was measured separately.Total growth and the frequency of development of new branches indicated noncontinious growth over the year. Differences between the mean growth rates at different times of the year were treated by an analysis of variance for dependent samples and the significance tested by a Duncan test. Between February and April the gorgonians grow significantly faster than during the rest of the year. Measurements of temperature and of water movement show a correlation of the period of maximum growth with minimum temperature and maximum water movement. Reduced growth during the summer is probably due to high light intensities. The intrinsic rate of natural increase could be calculated and the age of the colonies estimated. An empirical growth curve is approximated by a theoretical model. Estimates of the age of colonies up to the maximum possible size are thus possible.