Dressed in a wetsuit, hair piled on top of her head, bette Willis is dashing in the moonlight between two children's wading pools on a beach. Around her on the rough sand of Magnetic Island, off Queensland's coast, crouch others, peering into the pools with torches. There's excited chatter and a lot of concentrating, for tonight these marine scientists have front-row seats for one of the Great Barrier Reef's oldest and most beautiful spectacles. In the pools, Acropora corals plucked a few hours earlier from the warm sea are spawning, answering the call of the full moon as they do around this time every year. Hundreds of thousands of tiny cream and rose-colored bundles of eggs and sperm drift languidly to the surface, sending a sharp, salty smell into the night. By tomorrow night they'll be larvae; within a week each will be a tiny polyp, ready to begin building the protective exoskeleton that we know as coral. Though it's a journey Willis has watched many times in her 20-year study of the reef, it still thrills her. "This animal does such amazing things: it supports one of the most diverse ecosystems on earth and it builds structures visible from space," says the James Cook University coral biologist. "And yet, though it's a very simple animal, there's so much about it we don't know."
From the enigmas of its corals' birth to the uncertainty clouding their future, questions teem on Australia's Great Barrier Reef like the 1,500 species of fish that sparkle and dart through its coral gardens and seagrass meadows. Scientists puzzle over animal and coral species discovered decades ago even as new ones are found. And on the eve of the introduction into federal Parliament of a proposal to radically increase the reef's protection from commercial fishing, science is still baffled by many of the ways in which its 2,900 reefs and their inhabitants - from algae to worms to turtles - function and interact. Though two centuries have passed since His Majesty's Bark Endeavour picked its way through the reef's treacherous northern reaches, Captain Cook's description of it as "the Labyrinth" remains an apt tag for a watery world, bigger than New Zealand, in which humans remain modern explorers.
Relaxing in their bikinis on a tourist boat returning from a Sunday trip, Erin Graham and Katerina Kupcikova are hard to pick from the day-trippers around them. But they've been working today, finding and killing the crown-of-thorns starfish that remain one of the reef's most confounding scourges. The spiky coral eaters are thought to have existed on the reef for thousands of years, but since they were first noticed in plague numbers on certain reefs in the 1960s, millions of dollars have been spent trying to understand them. With little luck. Today scientists remain divided even on the cause of the outbreaks: are they part of a natural cycle, or are they caused by agricultural run-off, which feeds the phytoplankton that starfish larvae love? Speaking of the $A13 million spent on research over the past 15 years, Virginia Chadwick, chair of the Great Barrier Reef Marine Park Authority (gbrmpa) says: "With great respect to the scientists, from a practical management point of view it has not actually helped enormously."
Instead divers like Graham and Kupcikova keep the starfish at bay with fatal injections of sodium bisulphate. They're volunteers, but some big tourist operators each spend up to $A250,000 a year on divers to keep the reefs they visit pretty - across the rest of the 350,000-sq.-km World Heritage Area, there's monitoring but no control. This trip has been a good day. Graham and Kupcikova have found only 33 starfish; three months ago they were killing more than 50 each a day. But regardless of how many they find, these marine biology students are happy just diving the reef as often as they can during their summer break - both Graham, who left an IT career in Colorado this year to study in Townsville, and Kupcikova, who moved from the Czech Republic to do the same, have been bitten by the reef bug. "I love the mystery of it, that there's so much down there we don't know about," says Kupcikova. "It's like living on two planets, one up here and one down there."
Like other planets, the Great Barrier Reef has yet to yield all its secrets. Some of its reefs have never been dived or named; its oldest living coral may or may not be an 8-m giant Porites in the south of the park, which began growing 600 years before Cook arrived. And even less well known than its heavily studied coral communities are the marine park's vast seabed and its biodiversity. Last month the Australian Institute of Marine Science (aims), the Commonwealth Scientific and Industrial Research Organisation (csiro) and the CRC Reef Research Centre began a three-year project to probe those unfamiliar depths. Though it's too soon to say what new species or even potential pharmaceuticals might be found there, the 250 sites sampled have offered, says aims project leader Peter Doherty, "fascinating glimpses of life on the seabed," such as giant sponge gardens that may be hidden highways for fish traveling from spawning grounds to adult homes. "For the inter-reef areas, our knowledge is just a stage beyond superficial."
It's not just the Great Barrier Reef's depths that have been neglected - its shallowest waters also remain poorly understood. But this month Angus Thompson will don his diving gear as part of the first ever comprehensive survey of the marine park's inshore reefs. After more than a decade tracking the health of 50 reefs across the World Heritage Area for the aims Long Term Monitoring Program, Thompson considers a study of inshore reefs - those within 20 km of the coast which scientists consider most at risk from development and land-use run-off - is long overdue. Monitoring program leader Hugh Sweatman blames the lack of inshore monitoring on a shortage of funds: "Everyone wants the information but no one wants to pay for it." Besides, inshore reefs don't have the same appeal as those further out. Thompson expects the reef waters to be so turbid his team will have to hold onto a tape measure to stay together while they work. The risk of crocodiles or painful jellyfish stings is just part of the job. "There's only piecemeal information around now about these reefs," says Thompson. "We need to go and see what they look like."
Navigating through murky waters is possibly just as tricky as following a 1-cm-long fish larva as it swims, which is what Australian Museum fish scientist Jeff Leis and his team will be doing this month on Lizard Island, north of Cairns. Trying to discover how young fish choose where to settle, Leis and Canadian researchers will release a single silvery or transparent larva and follow it for 10 minutes, measuring its speed and direction. "It takes practice," Leis says. In the island's lab, his Ph.D. student Kelly Wright will use tiny electrodes on the skulls of larvae - the first such experiment on reef fish - to gauge their responses to different frequencies and odors in an attempt to discover how much they use the scents and sounds of reefs to guide them to a new home. The research isn't mere curiosity; finding out how larvae navigate and where they go would be invaluable in deciding which areas to protect from fishing. Until 1996, researchers assumed the larvae were carried helplessly on currents, suggesting protected areas should be based on current flows. But recent work by Leis and others confirms that some larvae can not only swim - often twice as fast as the currents they encounter around Lizard, which run at 10-15 cm/sec. - but also hear and smell. Although it's still not clear at what point in their larval stage such talents kick in, or whether they can smell individual reefs or just different parts of reefs, Leis says such discoveries are forcing a reconsideration of the ways in which reefs are interconnected - and therefore of strategies to protect them: "It indicates we're operating on much smaller scales, like a mosaic pattern of protection," he says, "and that's a completely new perspective."