Hyperproduction of mucilages by micro and macro algae in the Tyrrhenian Sea

Mucilages appeared in the Tyrrhenian Sea in 1991 in two forms, pelagic and benthic, the first kind produced by planktonic species of the spring facies, mostly diatoms, the latter instead produced by adnate filamentous algae. Evidence is presented that the coenose of pelagic mucilage found during summer is that of the spring facies, mostly diatoms, which are considered to the producer species of mucilages. Yet, the coenose inside mucilages in comparison with the summer coenose of the surrounding waters appears to be biologically less active. Among the environmental factors responsible for the mucilage phenomenon high NP ratios seem to be a necessary but not sufficient condition. Enquiries among fishermen confirm that marine mucilages are a common occurrence also in the Tyrrhenian Sea, although events are less spectacular than those known from the Adriatic Sea.