Microheterotrophic utilization of mucus released by the Mediterranean coral Cladocora cespitosa

The amount of mucus released by the Mediterranean coral Cladocora cespitosa (L.) was determined in laboratory experiments and the incorporation of mucus into bacterial biomass was investigated by means of incubation experiments in 1984. Mean mucus release was 8.5 μg (mucus dry wt) pclyp^-1 h^-1 and amounted to 44% of the respiratory carbon losses of the coral since mean organic carbon content of freshly collected mucus was 102.2μg C mg (mucus dry wt)^-1. Due to the abundance of C. cespitosa in the shallow littoral of the Bight of Piran, the energy content of mucus released is estimated to correspond to about 20% of the phytoplankton primary production in this area. Furthermore, the carbon conversion efficiency of 20% obtained from the bacterial population during decomposition of mucus indicates the high nutritional value of C. cespitosa mucus, although bacterial carbon onto mucus particles contributes less than 0.1% to the total organic carbon pool of the mucus.