Abstract
The first invasive record of the green alga Caulerpa racemosa (Forsskal) J. Agardh in the Mediterranean Sea was in 1990 in Tripoli (Libya) (J. Agardh) and since that period, this Chlorophyta has been rapidly spreading to all Mediterranean countries. However, very few assessment studies have been carried out along the Algerian coast. In this paper, we present, for the first time new observation data concerning an indicated proliferation of this invasive species in Salamandre and Stidia (Gulf of Arzew, western Algeria); both these sites are very important for sea fishing activities and traffic.