NO DELETERIOUS ALTERATIONS IN POSIDONIA BEDS IN THE BAY OF MENTON (FRANCE) EIGHT YEARS AFTER CAULERPA TAXIFOLIA COLONIZATION

High-resolution multispectral imagery, aerial photography, and SCUBA diving surveys were used to determine if there had been any significant alteration in the dimensions of Posidonia oceanica beds in the Bay of Menton, French Riviera, since colonization of the green alga Caulerpa taxifolia began in the late 1980s. After 8 years of direct contact, there was no evidence of a decrease in the abundance of P. oceanica. On the contrary, the integrity of a seagrass bed had increased in the first area colonized by Caulerpa taxifolia on the eastern side of Cape Martin and, in a more recently colonized central part of the bay, established tufts of Posidonia were isolated from the alga by well-defined exclusion zones.