Synchronous release of male gametes of Caulerpa taxifolia (Caulerpales, Chlorophyta) in the Mediterranean Sea

Abstract

Fifteen years after the first report of the presence of the tropical green alga Caulerpa taxifolia (Chlorophyta) in the Mediterranean Sea off the shores of Monaco, this alga is now present in the waters of five Mediterranean countries. This rapid, broad dissemination is believed to have occurred solely by thallus fragmentation, because sexual reproduction, common in tropical Caulerpa species, has not been demonstrated in Mediterranean C. taxifolia. Here, we report field observations of the synchronous formation and release of male gametes by the Mediterranean strain of C. taxifolia. As in related species living in tropical regions, gamete release was synchronized by light intensity. Despite the prolific release of male gametes, sexual reproduction apparently does not occur, because female gametes are absent.