Doughnuts with the Prince

Andrew Sugden

  • Killer Algae: The True Tale of Biological Invasion by Alexandre Meinesz, translated by Daniel Simberloff
    Chicago, 360 pp, £17.50, December 1999, ISBN 0 226 51922 8

In 1984, a small patch, no more than a metre square, of the tropical alga Caulerpa taxifolia was discovered in the Mediterranean – where it had never been seen before – growing on the sea-bed immediately below the Oceanographic Museum of Monaco, then under Jacques Cousteau’s directorship. Five years later, the area of the patch had extended to a hectare. In July 1990, another colony of the same alga appeared at Cap Martin in France, 5 kilometres to the east, and in September of the same year it was found near Toulon, 150 kilometres to the west. In 1992, patches were discovered in the Balearics. By the following year, Caulerpa had spread to Italy, as far as the whirlpool of Scylla and Charybdis, and in 1994 it turned up in the coastal waters of Croatia. By the end of 1996, the alga had invaded and occupied 70 sites on the northern Mediterranean coast, spreading over a total area of more than thirty square kilometres and to a depth of more than a hundred metres.

Alexandre Meinesz, a marine biologist from the University of Nice, had his first encounter with the colony of Caulerpa taxifolia beneath the Oceanographic Museum in the late summer of 1989. The museum employee who first discovered the patch of alga had told a colleague of Meinesz about the discovery, and Meinesz learned of it in early 1988. Meinesz was at first merely curious, and over the following months frequently asked his colleague about the progress of the patch: ‘He knew of my great interest in algae of the order Caulerpales, and he was confident that I would be discreet. I agreed to wait quietly for other news of this introduction of an exotic species.’ The need for discretion is not fully explained. Perhaps somebody’s job at the museum might have been at risk; perhaps a minor scientific coup could be pulled off by whoever first reported the discovery of this oddity. Perhaps it was a naturalist’s inquisitiveness that held Meinesz back: he had devoted much of his research career to the study of these algae, and his first impulse on hearing of a new specimen in unfamiliar surroundings would have been to wait and see what happened; at the very least, he would have wanted to see it for himself. And, though it was certainly odd that a tropical species should survive the cool Mediterranean winters, all his experience of Caulerpa taxifolia – normally a spindly plant that grows sparsely in its native waters – would not have led him to suspect that it could become a rampant invader. Perhaps there were incipient feelings of guilt: Meinesz and some of his colleagues had a few years before recommended the use of Caulerpa for decorative use in aquaria, and aquarium waste is the most likely source of the invasion. Whatever the reason, Meinesz was unprepared for what he would find when he had his first look at the new colony.

Underwater, the sea floor ten metres down appeared blurred and all green despite the good visibility. I tried to distinguish contrasting, relieved surfaces, but everything seemed blanketed in green. I suddenly could not believe my eyes: Caulerpa covered everything. It was magnificent and also very surprising ... Perplexed, I caressed the algae with my outstretched hand. It took me a while to react, my emotion was so great ... The tremendous size of the various parts of the plant was astonishing.

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