Thirty years ago, a tropical alga escaped from a Monegasque aquarium. Since then, the Caulerpa taxifolia has proliferated in the Mediterranean. Natural scientists and Corsican coastal managers are concerned because no means of control is effective. Because of its density, it stops the light and smothers the Posidonia meadows, which are at the marine ecosystem. Two other invasive Caulerpa species also threaten marine biodiversity, the C. racemosa, and the C. distichophylla.