Mediterranean Sea invaded by hundreds of alien species

Washington: A new study has revealed that the coastal environments of the eastern Mediterranean Sea have been invaded by more than 900 new alien species in recent decades, including the poisonous pufferfish.

The four-year study conducted at the University of Gothenburg also found that the invasion has affected the whole food chain system in the area.

"The Mediterranean is the world``s most invaded sea, but our understanding of how alien species affect ecosystems is inhibited by a lack of basic knowledge of the animal and plant communities on the coast,” said Stefan Kalogirou of the Department of Marine Ecology at the University of Gothenburg.

“Once species have become established in the Mediterranean it is almost impossible to eradicate them," he said.

Over a period of four years Kalogirou, in cooperation with the Hellenic Centre for Marine Research, has studied the structure and function of fish communities in sea-grass meadows and on sandy bottoms in two important coastal environments on the island of Rhodes in south-eastern Greece.

His study has provided important insights into invasion biology, that is to say possible ecological consequences of alien species in the food chain.

"The results show a clear ecological impact when alien species either become dominant, like pufferfish, or are piscivores, like barracuda and cornetfish. It is evident that the food chain is being restructured, but the lack of previous studies limited our conclusions," said Kalogirou.

The poisonous pufferfish is one of the alien species that have recently been introduced.

The pufferfish toxin, tetrodotoxin, causes muscle paralysis, which can lead to respiratory arrest. In the worst case the outcome can be fatal.

In the coastal environments that Kalogirou has studied, the pufferfish has become a dominant species, which has led to both ecological and social effects.


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