One of the world's worst weeds, Caulerpa taxifolia, has been eradicated from a lagoon in southern California, government officials reported last month. It was the alga's only known invasion in the Western Hemisphere.
Once marketed globally for use in aquariums, this captive-reared alga seems to have evolved into a form quite unlike its wild brethren (SN: 7/4/98, p. 8: http://www.sciencenews.org/pages/sn_arc98/7_4_98/bob1.htm). For instance, the escaped alga survives winter chills that would kill its wild kin and has almost no predators. Like a dense shag carpet, it smothers natural underwater inhabitants. Since the species' release in Monaco 2 decades ago, the alga has blanketed large portions of the Mediterranean. The U.S. infestation seemed to have resulted from a separate aquarium discard.