By Alex Kirby BBC News Online environment correspondent

Cara Hughes takes samples on the Virginian shore

They told BBC Radio 4's environment programme Costing The Earth the storms often lead to increases in population.

After Hurricane Isabel, which caused havoc on the US eastern seaboard in September 2003, some species doubled in number, and others also showed a boost.

But with hurricanes becoming far more frequent, the programme also heard from Americans anxious about their future.

A hurricane is part of a natural cycle, it's almost like a cleaning process Herb Austin, Virginia Institute of Marine Science

Cara Hughes, from the University of Wales at Bangor, UK, was studying the organisms living in the sediments and mudflats off the eastern shore of Virginia shortly before Isabel struck. The area is dominated by polychaete (segmented) worms, small crustaceans and molluscs.

Cara, who went back to the mudflats soon after the hurricane, told the programme: "The samples showed quite a dramatic increase in the number of species. Those normally found offshore were tumbled and swept in by the power of the waves and the wind... some species had doubled or had an even greater increase.

"Forest fires and other natural disasters actually stop some species becoming overly competitive. Even though many of these organisms are very small, the repercussions could be far-reaching. The animals that come and feed here such as the blue crab are very important commercially in this area."

Natural cycle

Cara's supervisor, Professor Mark Luckenbach of the Virginia Institute of Marine Science, said he was surprised at the increase in species diversity the hurricane produced.

A colleague at the institute, Herb Austin, works on a programme that has monitored fish populations in Chesapeake Bay for more than 50 years. He says catches of some species of the croaker family have increased almost tenfold since Isabel struck.

He told Costing The Earth: "A hurricane is part of a natural cycle; it's almost like a cleaning process. Hurricanes in this area have more than doubled in the last decade. Wintertime temperatures here in the bay are two degrees C warmer than they were 40 years ago."

Barry Truitt, the chief conservation scientist of the Nature Conservancy, said hurricanes were necessary to maintain the habitat shore-nesting birds needed, and also to control predators.

He said: "The Ash Wednesday storm in 1962 I firmly believe killed off all the red foxes and racoons in this area, though now they're coming back.

How to get around on Tangier Island

"We want to see a storm that's big enough to knock all these predators off on the islands. It's not a catastrophe in Nature to have a storm."

Mr Truitt says beaches are moved so rapidly by storms that they are in effect "high-speed real estate", where traditionally people do not build their homes. He is hesitant about building there now: "We're going to have to strategically decide what pieces of the coast are worth saving.

"If you want to build a house on a barrier island and you've got the money to do it you should be able to do it. But don't ask me and my government and my tax money to go to saving your home the first time it's threatened by a storm."

The federal government is planning to spend $3m on building a sea wall to protect Tangier Island, a low-lying Chesapeake Bay island which is home to just over 600 people.

The people of Tangier stoutly defend their right to be protected against the elements. But many conservationists think it would be wiser in time to surrender places like Tangier to the sea.