Skeleton growth and density pattern of the temperate, zooxanthellate scleractinian Cladocora caespitosa from the Ligurian Sea (NW Mediterranean)

X-radiographs of corallites of the zooxanthellate coral Cladocora caespitos a (L.), collected in the Ligurian Sea between 3 and 27 m depth, were examin ed. C. caespitosa deposits 2 bands yr(-1); the high density band is deposit ed during winter (November to March) while the low density band is deposite d in summer. Average growth rates ranged from 1.36 +/- 0.58 to 4.42 +/- 1.6 1 mm yr(-1). No differences in the timing of band deposition were found bet ween shallow and deep colonies. A comparison of the band pattern with month ly temperature-irradiance measurements from the Ligurian Sea, and with lite rature data on the photosynthetic efficiency of zooxanthellae, led us to hy pothesise a mechanism of growth with a low dependency on autotrophy.