Bathers in Greek Islands' holiday resorts and other Mediterranean tourist hotspots are warned to be on the lookout for a poisonous puffer fish. The poisonous fish (pufferfish) has recently appeared in the waters of the eastern Mediterranean and has a powerful toxin that can cause muscle paralysis and breathing difficulties.
The sting is delivered through sharp spikes that cover the fish's body. The fish puffs itself up into a spike encrusted ball when alarmed.
The poisonous spikes can even be fatal. The pufferfish is one of more than 900 new alien species found in coastal ecosystems of the eastern Mediterranean Sea over the past years according to a four-year investigation by a Greek scientists, which focused on coastal areas around Rhodes.
The scientists claim the entire marine food chain has undergone major changes and pressures as many non endemic species have moved into Mediterranean waters.
Researchers at the University of Gothenburg in Sweden, in cooperation with the Greek Centre for Marine Research (HCMR), says that the Mediterranean has accepted a large invasion of alien species but warn there is insufficient understanding of how this invasion has affected ecosystems, animals and plants.
In the coastal ecosystems around the holiday island of Rhodes the pufferfish seem to have acquired a dominant position, with ecological and marine impacts.
But the study insists there is insufficient information and knowledge to make an appropriate risk assessment of the impact of these alien species.
The report says the building of the Suez Canal in 1869 probably opened a path for the spread of species from other oceans into the Mediterranean. The cumulative effects have brought dramatic changes to plants and fish, especially in ecosystems in the south-eastern Aegean Sea, near to to Rhodes.
Scientists say the sandy sea bottom and seagrass bed have helped the emergence and establishment of alien species causing major changes in the marine food chain.