Brightly coloured interlopers are threatening to crowd out native species less suited to the ever-warmer and more polluted waters around southern Europe, said Italy's Central Institute for Scientific Research and Applied Technology for the Sea. It said the Mediterranean's first species of tropical fish arrived in the Thirties, three decades after the opening of the Suez Canal. Since then, 55 Red Sea species have made their way in via the canal.
The findings of new research on the problem were presented to the Environment Minister, Edo Ronchi, yesterday.
"The tropical fish, having evolved in conditions of rapid natural change in highly competitive environments like the Red Sea, can easily spread in the Mediterranean," said Franco Andaloro, the author of the study. "The competition with Mediterranean species in terms of habitat selection, the search for food and reproductive success could lead, in extreme conditions, to the extinction of the weaker species."
Scores of other tropical species have entered through other means, including through the Gilbraltar Straits and on ships. The overall level of fish in the Mediterranean has increased by 20 per cent thanks to the influx from tropical seas. And in comparison with a native population weakened by pollution and over-fishing, the newcomers are thriving among the 530 indigenous species.
The study warned that the whole ecology of the sea is being altered by the reordering of the food chain.