Mortality of commercial sponges: Incidence in two mediterranean areas

In 1986 a severe epidemic affecting horny sponges broke out in several areas of the Mediterranean Sea. The disease rapidly spread to species of marketing interest belonging to the genera Spongia and Hippospongia. Ultrastructural studies of Spongia officinalis evidenced two main features: 1) peculiar bacteria with irregularly dotted electron‐dense walls within the tissue; 2) profound alterations of the skeleton with bacterial damage of fibres. These lesions made the sponges unsuitable for commercial purposes. Long‐term investigation in the Marsala Lagoon (northwestern Sicily) and at the Portofino Promontory (eastern Ligurian coast) in 1986–1989 evidenced striking incidence of the disease on the abundance of sponges. Reparative processes were also present in specimens collected during the epidemic that affected even other demosponges besides horny sponges. The etiology of the disease is discussed.