The Mediterranean’s delicate biodiversity is at risk due to an «invasion» of foreign marine species, according to experts who say hundreds of new fish have arrived in the last 140 years. The findings, published in the online scientific journal PloS One, have been confirmed by the Hellenic Center for Marine Research (HCMR). According to Argyro Zenetos of the HCMR, at least one new species arrives in the Mediterranean every week. Zenetos said that between 960 and 975 «foreign species» have been recorded by scientists in the Greek seas over the past 140 years and reported an «aggressive increase» in different species of fish in the Mediterranean over the last decade, observing that the number of recorded types had doubled during that period. Zenetos and her team, who have been monitoring the marine population for more than 25 years, highlighted a particular problem in the waters of the Saronic Gulf. Zenetos noted that an increase in the number of research projects being carried out in the Aegean had helped to keep track of the sharp increase in the marine population. Most of the new species are believed to have reached the Mediterranean aboard ships in the seawater that the vessels use as ballast. But Zenetos said there were so many new species in the Mediterranean that it was unlikely they had all arrived in this way. It is considered likely that many species came via the Suez Canal and the Strait of Gibraltar. Asked how the foreign species survive in their new environment, Zenetos cited several factors including the impact of climate change, overfishing and pollution. «We are seeing the creation of a new kind of sea and it is likely we will stop seeing many species that we recognize,» she said.