Highly significant relationships between size and weight (p < 0,1 %) w
ere determined in four colonial species : Alcyonium digitatum (W = 0.3
97 T1.987, N = 53, r = 0.945), Abietinaria abietina (W = 0.023 T1.716,
N = 111, r = 0.960), Hydrallmania falcata (W = 0.048 T1.526, N = 87,
r = 0.947) and Sertularia cupressina (W = 0.002 T2.315, N = 58, r = 0.
958). The aim of this study is to estimate the production of colonial
species by methods normally used for solitary species. To valid this p
rocess, biomass of the most abundant species, A. digitatum, was calcul
ated by coupling the length histogram with the weight-length relations
hip and compared with real data. The difference between these two valu
es (2.30 %) is very low.