GROWTH-RATES OF 3 SYMBIOTIC CORALS IN THE RED-SEA

Growth rates of the hydrocoral Millepora dichotoma and the corals Acro pora variabilis and Stylophora pistillata were studied by applying the buoyant weighing technique and statistical analysis. We found that M. dichotoma exhibited the slowest relative growth, whereas S. pistillat a and A. variabilis were faster growers, with weight-based doubling ti mes of about 3, 1.2, and 1.3 yr, respectively. In the case of A. varia bilis, as well as in bladed colonies of M. dichotoma, growth rare per unit weight was size independent, whereas in S pistillata a clear posi tive correlation was found between the relative growth rates and the i nitial colony buoyant weights. M. dichotoma and A. variabilis demonstr ated distinct seasonal growth oscillations (2-month. time lag with res pect to the seasonal trend of the ambient water temperature). We concl ude that the oscillations in the absolute growth rate of corals result ed from the seasonal changes in water temperature.