Evolution of the populations of Cystoseira balearica (Phaeophyceae) and epiphytic Bangiophyceae in the Bay of Calvi (Corsica) in the last eight years

In a number of stations covering the Bay of Calvi (Corsica, Mediterranean Sea) we studied the development of the macroscopic brown alga Cyctoseira balearica and of the epiphytic microscopic Bangiophyceae. Cystoseira balearica is a major component of infralittoral communities on rocky substrates and Bangiophyceae have been considered indicators of eutrophication. The epiphytic Bangiophyceae have indeed their optimal developement near the sewages discharges (especially in summer) and near the town of Calvi. Since 1981 an increase is observed in the abundance of the Bangiophycae. Cystoseira balearica, a pollution-sensitive species, is not present in the harbours of the town of Cavi and near the sewage dicharges. Since 1980 the coverage and the standing crop of this alga have decreased. The increase of Bangiophyceae and the concurrent decrease of Cyctoseira balearica seem to indicate an increasing pollution of the waters of the Bay of Calvi in the period 1980 - 1988.