Faint ohonoch sydd wedi clywed am y chwyn dinistriol 'ma sy'n dinistrio ecosystem y Med?
In the early 1980s, the curator of the tropical aquarium at Stuttgart, Germany, noticed the exceptional properties of a beautiful green alga, Caulerpa taxifolia, used as decoration in the presentation of multicolored tropical fishes. In contrast to other algae, it does not wither, it grows with astounding vigor, it resists cool water temperatures, and it serves as a secondary food source for herbivorous tropical fishes. Specialists quickly learned about these qualities, and public aquaria acquired cuttings.
This is how it arrived at the Oceanographic Museum of Monaco, where it was cultivated beginning in 1982. Two years later, the alga was discovered in nature, under the windows of this celebrated building. At that time, the beautiful stranger occupied only a square meter of Mediterranean bottom. Six years later, the alga was noted on the French coast five kilometers from Monaco; its detrimental impact on coastal ecosystems was deplored. The alga grows everywhere, from the surface to the lower limits of underwater vegetation. It grows as well in front of capes swept by storms and currents as on the soft bottoms of sheltered bays, on the polluted mud of harbors as on stretches of bottom with a diverse flora and fauna. Highly toxic, it barely interests herbivores; they have not hindered its spread. It is thus growing unrestrained, covering and then eliminating many plant and animal species. A new equilibrium is reached when the alga forms a dense, uniform carpet that persists from year to year.
After having selected it for aquaria from among numerous imported algal species, after having dumped it into the sea, humans fostered its dissemination in nature. Yacht anchors and fishing gear have carried it from anchorage to anchorage and from harbor to harbor, sometimes over great distances. The Italian and Spanish coasts were reached by 1992, that of Croatia by 1995. By late 1997, ninety-nine invaded sites totaling more than 4,600 hectares have been inventoried.
No one has ever been killed by Caulerpa taxifolia, known as the "killer alga." For, contrary to what its media nickname might suggest, this prolific alga is primarily an ecological threat. All relevant research indicates an unlimited spread. Its control is more difficult every year, and its eradication, envisaged at the beginning of the invasion, can now be classed only as a utopian dream. The introduction of this dangerous alga therefore threatens to initiate a profound disruption of the coastal Mediterranean environment. The story of the "killer alga" has, unfortunately, just begun.