Marine biologists have succeeded in identifying hordes of marine species around the world before they vanish.
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Researchers from 80 countries, who compiled the world's comprehensive inventory of marine biology, the Census of Marine Life, report that more than 230,000 marine creatures have been collected and preserved, with thousands more added in the past decade or so.
A good many of these animals live in or around reefs. "This is why it's crucial that we protect our reefs from further harm," says marine biologist Sue Sargent, the conservation partnerships manager at Burnett Mary Regional Group.
Her warning is well placed. Rising ocean temperatures are already showing signs of affecting the Pacific Ocean, the US National Oceanic and Atmospheric Administration warns.
The administration has officially declared a global bleaching event as coral reefs turn white. This is the third global bleaching event in recorded history and is likely to worsen in coming months.
"This could be a very damaging bleaching event and is due to ocean warming," says Professor Maria Byrne of Sydney University. "The bleaching is widespread across the Pacific and Australian scientists are on watch – monitoring Australia's coral reefs."
Added to the woes of coral bleaching, she explains, is a complex of interacting stressors such as overfishing and pollution.
Marine scientists are rallying to the cause, searching for novel ways to save what is left of reefs.
To protect Australia's Great Barrier Reef, a number of new measures are being tried, including poison injections and robot submarines to deal with crown-of-thorns starfish and the use of reef-preserving tropical sea cucumbers.
Cucumber time
"Sea cucumbers – marine animals with oblong-shaped bodies and leathery skins that inhabit seafloors the world over – play a vital role in reducing the harmful impact of ocean acidification on coral growth," says Professor Byrne.
"One of the byproducts of the sea cucumber's digestion of organic matter – which bonds to the calcium carbonate tropical sands that they ingest – is the creation of a local environment that favours coral growth."
To survive, Professor Byrne explains, coral reefs must grow their skeletons faster than they are eroded from the reef as oceans get more acidic.
"When they ingest sand, the natural digestive processes in the sea cucumber's gut increases the pH levels of water on the reef where they defecate – countering the negative effects of acidification," she says.
The research, published in the Journal of Geophysical Research, was carried out by an international team of scientists from Sydney University, Stanford's Carnegie Institute for Science and other institutions studying the impact of climate change on reefs.
About 30 species of cucumbers are commercially harvested by fisheries along the Great Barrier Reef and throughout the tropics.
"Protecting the habitat of sea cucumbers is probably one of the best things to do to encourage their growth in the wild," says Ms Sargent. "We can help by making sure we don't overfish the ones we have. But we're going to need a lot more sea cucumbers."
They can be collected easily, she says, but their biology does not allow them to recover quickly. "Many species grow slowly and, with both good and poor breeding years, it can take a long time for stocks to be replenished from overfishing," Ms Sargent says.
"We urgently need to understand the impact of removing sea cucumbers and other invertebrates on reef health and resilience at a time when reefs face an uncertain future," Professor Byrne says.
Coral picture
Recent reports have suggested that the past century or so of ocean warming has benefited the growth of some corals – particularly for colder, high-latitude reefs.
This is not the whole story, Professor Byrne says. "While a small increase in temperature can facilitate coral growth in certain locations, too much heat – and this is where we are heading – will go beyond lethal thresholds, as seen in some coral bleaching events," she says.
"Climate-change-induced ocean warming and ocean acidification are both causing significant changes in organisms, habitats, biotic communities and ecosystems," Professor Byrne says, emphasising the word "both".
"These changes are predicted to cause irreversible negative impacts on living systems by the middle to the end of the 21st century," she says.
Community action
Living corals are not competitors but co-operative communities of myriad tiny individuals, called polyps that live in symbiosis with algae and trap food from the tides. The algae in the coral tissues help build stony skeletons, which form reefs.
In the words of University College London biologist Steve Jones, coral has become "a canary in the ecological coal mine". In his book Coral: A Pessimist in Paradise, Jones writes: "The future of the reefs is bleak indeed."
Our national marine biological asset, the Great Barrier Reef, is not so great any more, he says. Could it one day follow the fate of the Seychelles' once-complex ecosystem, now reduced to seaweed-covered rubble?
In the 1950s, he notes, roughly one-third of the Great Barrier Reef was in reasonable condition. When he visited it a decade ago, about one-quarter was satisfactory; now, he reckons, the figure is one part in five.
Australia, he says, pollutes more per head than anywhere else bar the United States, referring to the nation's per capita emissions of carbon dioxide.
Bay reef
Although much attention is devoted to the Great Barrier Reef, Melbourne's Port Phillip Bay has vibrant sea gardens that are also in need of protection.
More than half of the plants and animals living along the southern Australian coastline are found nowhere else in the world, says Museum Victoria zoologist Gary Poore.
So far, scientists have catalogued 118 species of seaweeds (one of the most diverse areas for seaweeds on earth), 43 species of resident fish (including Victoria's marine emblem, the weedy sea-dragon), along with our own Burrunan bottlenose dolphin, found only in Victorian waters.
"The diversity of the bay is nowhere near that of the Barrier Reef," Dr Poore says. "Diversity generally is correlated with the size of the environment, among other factors, so I'd not expect it."
But, he adds, the discovery of many species in the bay, and nearby Western Port, "has made marine biologists realise that diversity was higher in southern temperate environments than previously thought possible".
Aquatic scientist Sheree Marris agrees. "Australia's southern marine environments are as diverse and unique as our land environments," she says. "And our southern waters should not be overlooked for wonders of the deep."
Ms Marris leads a campaign, Melbourne Down Under, which aims to put our underwater realm on the global marine map. Using world-class imagery, the campaign features a flagship book, a documentary DVD – produced by Jarrod Boord of Streamline Media – and a travelling outdoor exhibition.
The plethora of diverse sponges, found on the 90-metre-deep vertical reef faces in Bass Strait, as well as in crevices and deep caverns at Port Phillip Heads, are unlike any other marine community in Australian waters.
"This was the former channel of the ancient Yarra River and is the deepest area of ocean water in the whole of Bass Strait," Ms Marris says.
Yet most of the bay is relatively shallow and, in the saucer-shaped middle, reaches a maximum depth of 25 metres.
"It's an extraordinary world of colour and contradictions; birds whose wings turn into fins, fathers that give birth and enchanting weedy seadragons that sparkle like jewels," Ms Marris enthuses.
Earlier this year, Parks Victoria scientists, using a remote-controlled submersible equipped with underwater cameras, discovered a hidden world of hard and soft corals and fish species – including barracuda and longsnout boarfish – at depths of up to 100 metres in Wilsons Promontory National Park.
"The find left us in no doubt that southern Australia's deep reef habitats teem with life and ecologically important marine ecosystems," Dr Poore says.
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