By Richard Black
Environment correspondent, BBC News website
The stricken M/S Explorer sank off the Antarctic coast in November
Environmental campaigners are calling for greater restrictions on shipping around Antarctica in order to prevent damage to its unique ecosystems.
More tourists than ever before are visiting Antarctica, some in ships not designed for the harsh conditions.
Campaigners say the sinking of the M/S Explorer last year was a wake-up call.
The Antarctic and Southern Ocean Coalition (ASOC) is asking the International Maritime Organisation (IMO) to strengthen its rules.
The IMO's environment committee is meeting this week in London.
"The IMO is the only body that can agree stringent vessel standards, equipment and procedures in order to protect human life and the marine environment for all vessels using Antarctic waters," said James Barnes, ASOC's executive director.
ASOC and its allies are calling for the banning from Antarctic waters of ships that use heavy oil as fuel. They want to see tighter restrictions on the discharge of sewage and grey water, and a requirement that all vessels entering the region are strengthened to withstand icy conditions.
So enticing is the lure of the White Continent that Antarctic tourism has grown about five-fold in the last 15 years.
Figures from the International Association of Antarctica Tour Operators suggest that 37,552 tourists visited Antarctica during 2006-07, the majority arriving by sea.
ASOC is concerned that many of the vessels carrying them are not ice-strengthened. This makes serious accidents more likely, and increases the risk of an oil spillage if a ship gets into trouble.
They have documented six incidents in little more than a year which carried a risk of major contamination, the most notable being the holing of the M/S Explorer - probably by an iceberg - which resulted in the vessel sinking and an international rescue mission for passengers and crew.
Antarctica is the unique home to several varieties of penguin, an important base for others such as seals, and a vital feeding ground for whales.
"It's fragile, hostile at times, yet staggeringly beautiful," said Vassili Papastavrou, a biologist with the International Fund for Animal Welfare (Ifaw) which is backing ASOC's bid.
"You just don't get such abundance of wildlife in an undisturbed environment anywhere else in the world."
Antarctica is heavily regulated by the Antarctic Treaty and its various protocols and annexes.
SIX NEAR MISSES
November 2006: tourist ship M/V Lyubov Orlova runs aground in South Shetlands
January 2007: the M/V Nordkapp, also carrying tourists, spills fuel during a grounding
February 2007: Japanese whaling ship Nisshin Maru (above) suffers a serious fire, eventually limping back to port
November 2007: M/S Explorer, holed probably by an iceberg, sinks off the Antarctic Peninsula, with 100 people rescued
December 2007: yet another tourist vessel, the M/V Fram, loses power and drifts into an iceberg
December 2007: fishing boat Argos Georgia drifts among ice floes for 15 days after losing power
They ban mineral exploitation, limit uses of the continent to "peaceful purposes", and require member governments to protect the unique environment.
But the treaty has only 46 members, and governments broadly supporting the bid for greater regulations - including the UK - will have to convince the much larger IMO membership that the extra curbs are necessary.
Requiring ice-strengthening and banning ships fuelled by heavy oil would have an impact on businesses currently operating in the region, according to John Shears, head of the Environment and Information Division at the British Antarctic Survey (BAS) and senior environmental advisor to the UK delegation at Antarctic Treaty meetings.
"BAS's ice-strengthened research vessels use marine gas oil, which is like diesel fuel, and if it spills it will evaporate and disperse quickly in the sea," he told BBC News.
"A spill of heavy fuel oil would have a more significant environmental impact because the fuel coalesces in the cold water and is very persistent, making it exceptionally difficult to clean up.
"A ban would certainly affect some of the very large cruise ships."
The meeting of the IMO's Maritime Environment Protection Committee runs until Friday.