Exotic marine life of Italy's 'Blue Grotto' under threat from boom in tourism

One of the world's most extraordinary marine environments risks being destroyed by its popularity. The interior of Grotta Azzurra, "Blue Grotto", at Palinuro in the far south of Italy's Amalfi coast, is pitch black because of the narrowness of the cave's entrance. Yet the grotto's waters teem with exotic marine life, including giant sponges, oversize mussels and lobsters, and luridly coloured coral.

The reason marine life can survive inside the cave is because of the sulphidic springs that pipe hydrogen sulphide into its water. This provides a source of energy for the marine life, as it is a viable alternative to sunlight.

"In the pitch dark there is an explosion of life such as you can see in no other cave, a unique vision," said Professor Francesco Cinelli, a marine biologist at the University of Pisa who has been studying the grotto's ecosystem for the past 15 years. There is only one other place in the world, the experts say, where this phenomenon has been observed: in the black depths of the sea at the Galapagos Islands, at a depth of about 3,500 metres.

It was long thought impossible that life of any sort could be found at such frozen depths. But oversize, monstrous marine life like that at Grotta Azzurra is to be found there - for the same reason.

Professor Cinelli said: "To observe this sort of phenomena the Americans have to go down to a depth of 3,500 metres. But it's all right on our doorstep, here in Italian waters. Yet we are doing everything in our power to destroy this valuable and unique patrimony."

Palinuro's peculiar marine paradise has been studied intensively by Professor Cinelli and his colleagues over the past decade. But the site has also become a must-see for the tourists who flock to this coast every summer. And that is where the trouble starts.

Professor Silvano Focardi, president of Icram, an Italian marine research institute, said: "There are no controls on tourism in this area. Whenever there are enough tourists who want to go and see the caves, the boats set out."

They bring bright lights, noise, carbon dioxide and sweat, and they leave behind whatever they happen to throw overboard.

"An initiative to protect the cave is desperately urgent," Professor Focardi said. "But that in itself is not enough, we must do more. What is required is a large scale monitoring of our coasts so we can keep a close eye on the situation in the most sensitive areas and at the same time pursue research."

Professor Cinelli is launching a petition and plans legal action to halt the devastation of the cave.

How to minimise damage caused by visitors

The challenge of tourism in ecological hot spots such as the Grotta Azzurra - which is home to sea life including colourful sponges, pictured - is to strike a balance between access and preservation. At present access to the caves by trippers, brought by boat from nearby resorts, is completely uncontrolled. State authorities have yet to act on the issue but diving organisations in the area are taking the lead in trying to inculcate a more responsible approach to exploring the caves which dot Italy's west coast. Gordon Mackie, whose firm Tuscan Divers has a base in Basilicata, in the far south of Italy, said his customers brought up all sorts of rubbish discarded by tourists over the side of their boats. "It's strange but whenever tourists go into a cave in a boat they seem to feel they have to throw something over the side," Mr Mackie said. But divers can harm the caves too. "We discourage people from touching things," Mr Mackie said. "If you touch a stalactite you can leave sweat on this thing which has taken thousands of years to reach this state. Ideally you should do less harm than a fish passing through."