SCIENCE: THE SECRET SEA

We've explored most of Earth's dry land. But, says Matthew Brace, the oceans can still lead us to a wealth of information

The Oceans, Earth's final scientific frontier, are being explored more intensely than ever before. Scores of national and international undersea projects are underway all over the world as, increasingly, researchers focus their attention on the deep. Marine science is all the rage, and its professional exponents and a growing band of amateur divers are collectively being labelled the "Blue Movement".

This growth in submarine research is timely. Not only is 1998 the International Year of the Ocean but, more importantly, scientists have spent much of 1997 scratching their heads as they witnessed the devastation caused by the climatic phenomenon, El Nino, and its related effects around the globe.

The inaccessibility of the oceans and the high cost of submarine exploration have restricted research in the past, despite the widely held belief that many of the untold secrets of life on Earth are locked away under the waves. What work has been done has yielded sunken treasure: new species, violent plate tectonics, and the unpredictability of currents. But this type of research has often concentrated on small areas. Marine scientists are now looking more at the global effects of the oceans' currents and the effects they have on the environments of the planet.

There are at least six major international marine research programmes underway and numerous smaller expeditions using thousands of scientists and millions of pounds. Professor John Shepherd, director of the Southampton Oceanographic Centre, believes the volume of research is due partly to an increased understanding by policy makers of the part oceans play in the global climate.

"Globally, there are more oceanographic programmes going on now than ever before and Britain is among the world leaders. We have to cede precedence to the US, but we're in the top few," he says. "I have the impression that the rest of the world - the politicians, the green lobby and big business - is catching up with us now. In the UK, the research on climate change has been led by the meteor- ologists, but lately the oceanographic community has succeeded in getting its act together."

Nigel Winser, deputy director of the Royal Geographical Society (with the Institute of British Geographers) agrees: "There have been far more applications coming in to us in recent years from people wanting to do marine science work. Today, a third of the world's surface area is still considered to be wilderness but exploration, as Livingstone, Columbus or Cook would have defined it, is mainly confined to the ocean depths."

The Natural Environment Research Council, Britain's chief funding body for science and environmental research, allocates pounds 40m a year to marine sciences which includes deep ocean work and coastal and estuarine studies. Dr Phillip William-son, the secretary of the marine science and technology board of NERC, said despite the reported growth in oceanographic research, NERC has not received a disproportionately higher number of marine study grant proposals. This could be due to more corporate sponsorship of individual programmes. A new international programme, the Shoals of Capricorn, has benefited from donations from the Omega Watch Company.

Shoals is a multi-disciplinary, two-year study of a 115km-patch of Indian Ocean between Mauritius and the Seychelles. Run jointly by the Royal Geographical Society and the Royal Society, the pounds 1.5m project will, in May, begin the examination of a 2,000km-long, calcareous ridge just beneath the ocean's surface. Visible from space, it is thought to affect half the currents of the Indian Ocean. The programme's vice-chairman, Dr Nic Flemming, from the Southampton Oceanographic Centre, explains that it is vital to send divers in person to look at the ridge. Remote-sensing techniques can pick out the main factors of the oceans, but draw only broad images between areas of differing temperatures or currents.

"There is a grainy, mosaic pattern going on which the satellites don't pick up," says Dr Flemming. "So we are going to use people to do the research on the ground to fill in the detail of that mosaic and find out why the bits fit together. We want to try to find targets to work towards in the world's oceans using shallow water techniques which are significant enough to make a real dent in our understanding of the ocean envi- ronment. We were looking all over the world for a suitable site. We needed somewhere on a bio- geographical boundary with a very steep gradient which would give us a rapid change in temper-ature. The Mascarene Ridge, or the Shoals of Capricorn, provides just such a discontinuity."

The ridge seems not to have broken the surface like other reefs and formed small islands. This, Dr Flemming believes, could indicate a mysterious lack of growth since the last sea-level rise.

"Why does it seem to be planed off flat? Why hasn't the normal rate of growth continued here as it has elsewhere around the world, forming atolls above the surface? And does this have any influence on the fact that there seems to be no equivalent to El Nino in the Indian Ocean?

"We are not doing enough oceanographic research on a grand scale for the whole of the Indian Ocean that would answer that question but our research in currents around the Mascarene Ridge could give us some clues."

Shoals is not just dealing with oceanography. For Iain Watt, the programme's director and a marine ecologist, it is the amalgamation of different disciplines. "We are trying to take an integrated look at the processes of the area - which include water chemistry, geology, biology and fisheries, and bathymetry [the science of sounding seas] - to discover what is making this ocean tick," he says. "And there is a lot of emphasis on educating local populations in marine science skills so that they can continue this marine awareness in the future."

So if this area is so scientifically valuable and might lead scientists to solving the riddle of the ocean's currents, why hasn't it been studied before?

"The Indian Ocean is difficult to get to," explains Dr Flemming. "It is the least researched of all the oceans. The North Atlantic is the most researched because it is between two prosperous regions of the world; the North Pacific, too, because it has the US and Japan on its two shores. But there is no large, rich country with an Indian Ocean shore."

A second marine science programme is being carried out on board the British research vessel James Clark Ross, used by the British Antarctic Survey to make the trip south from the UK to the Antarctic each September and back again in April when the southern oceans are beginning to freeze. It covers 12,000km of water, passing through a range of ecosystems and physiochemical regions where conditions vary from sub-polar to tropical. Results from four cruises have been compiled by the Plymouth Marine Laboratory and contribute to the Atlantic Meridional Transect (AMT) project which validates satellite imagery of the colour of oceans, sea-surface temperatures and heights, and solar radiation, while collecting data on how ecosystems react to environmental changes.

A third marine programme, the World Ocean Circulation Experiment (WOCE) led by Dr John Gould, also based at Southampton, is concerned with producing improved computer models on currents for more accurate climate predictions.

"The oceans are, in the long term, as important as the atmosphere," says Dr Gould. "Climate is the result of the biosphere, oceans, atmosphere and ice, but one of the big unknowns is the role the oceans play. We know they share with the atmosphere the transport of heat and fresh water around the globe, but we need to understand those systems much more fully."

One key factor is measuring the shape of the sea surface, which can be done to within 2cm. The sea surface slopes like the surface of tea in a cup when swirled. Averaging the wave heights calculates the slope of the sea surface and where that slope is greatest is where the currents are greatest.

"Never before have we been able to look at the ocean as a global identity," says Dr Gould. "A research ship can look at only the bit of the ocean it is on. Satellites provide us with a framework of measurements on to which we can fit data from the ships. Together they can test and validate these ocean models." In May, the WOCE will release results from the biggest oceanographic experiment to date, involving 35 countries, lasting five years and costing (without satellite fees) over pounds 200m.

Praiseworthy as the current enthusiasm of the Blue Movement might be, it is on results like these that marine science will ultimately be judged. !