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Fragile oceans so vital to life
11:07am Wednesday 19th September 2012 in Features
Creole wrasse in a marine reserve at Saba in the Caribbean, an example of healthy seas. Picture: Callum Roberts
The world’s oceans sustain most of life on earth – yet we’re systematically polluting and over-fishing them to the point of exhaustion. A new exhibition at the University of York exposes the damage we are causing. STEPHEN LEWIS reports
IN THE middle of the Pacific Ocean there is a Texas-sized patch of floating plastic and other man-made junk. It has been gathered there by a pattern of currents known as a ‘gyre’. And it proves irresistible to albatrosses.
The great birds fly thousands of miles across the Pacific to gather food for their young, and they naturally prey on marine life that floats near the surface of the water. They swoop on the bits of floating plastic and other detritus, carry them back home, and feed them to their chicks – which starve to death, their bellies distended with bits of indigestible junk.
That patch of rubbish floating on the Pacific is known as the Great Eastern Garbage Patch. It is one conspicuous example of the way we are abusing and exploiting our oceans almost to the point of exhaustion.
To us, the oceans seem immense – almost endless in their untamed beauty and unpredictability. Seen from space, they cover more than two thirds of the globe. “And they constitute more than 95 per cent of the living space on our planet and are vitally important to life in the remaining five per cent,” says Callum Roberts, a professor of marine conservation at the University of York and one of the consultants on the BBC’s stunning Blue Planet series.
Yet they are fragile, too. “The thickness of the oceans is to the size of the earth as the skin of a peach is to the fruit inside,” says Prof Roberts, who is the author of a new book – Ocean of Life: How Our Seas Are Changing – and an exhibition based on it that opens at the University of York on Friday. The sad truth is that, over the past 100 years, because of our greed to consume more and more, and our carelessness about how we dump the waste products of our relentless consumption, we have polluted, over-fished and otherwise exploited the oceans to the point almost of catastrophe.
In the course of writing his book, Prof Roberts has marshalled an impressive array of statistics to demonstrate the damage we are doing. We have room for only a few here, but they make for frightening reading:
• Two-thirds of the world’s major fish stocks have been fished to collapse since 1950
• In the past decade, melting of Arctic sea ice has opened a connection between the Pacific and Atlantic oceans that had been shut for 800,000 years
• In 1998, the Indian Ocean became so hot that three-quarters of its corals died.
• More plastic was produced in the first ten years of the 21st century than in all of the previous century
• Near population centres every metre of beach can be polluted with tens or hundreds of thousands of pieces of plastic, most of it so small it looks like sand grains
• The world’s largest container ships and supertankers each emit more pollution than the world’s smallest countries.
• The oceans have absorbed a third of all the carbon dioxide emitted since the Industrial Revolution, causing seawater acidity to rise faster than at any time for 55 million years, with unpredictable and potentially disastrous consequences for life.
Over-fishing is perhaps the most obvious way in which we’re exploiting the oceans.
Intensive fishing has reduced the abundance of fish species we most enjoy eating to a tenth of their numbers a century ago, says Prof Roberts. In the waters off the coast of the UK, populations of fish such as halibut, ling, wolffish, common skate, angel shark and bluefin tuna have shrunk by more than 95 per cent in the past 120 years.
Over-fishing isn’t the only man-made threat to our oceans, however. Industrial and agricultural pollution is having a huge impact, too.
In many parts of the world agricultural nutrients used for fertilising soil are draining into the sea, causing a ‘bloom’ of tiny microscopic creatures known as plankton. These can grow so densely that, as they sink and rot following death, all the oxygen in the water is used up – creating ‘dead zones’ in which all the fish die.
Then there is global warming. Global sea temperatures have risen by 0.6 degrees C in the past 30 years, Prof Roberts says. It doesn’t sound like much – but it is enough to have had a dramatic effect on coral reefs, which are hugely sensitive to temperature.
He finds that statistic about three-quarters of the Indian Ocean’s corals dying in just one year in 1998 particularly alarming: because it was so completely ignored. “If three-quarters of forest trees had withered that year there would be near universal alarm,” he says. “Yet below water the oceans are out of sight and therefore out of mind. We are sleepwalking to disaster.”
Even that isn’t perhaps the worst. There is also the problem of acidification of the seas.
Since the start of the industrial revolution, the world’s oceans have absorbed about a third of all the carbon dioxide produced by man’s activities. When carbon dioxide is absorbed into water, it makes the water more acidic. As a result, the acidity of the oceans has increased by 30 per cent since the start of the industrial revolution – and some experts predict it could rise a further 150 per cent by 2100, Prof Roberts says.
That could be potentially catastrophic. There are certain types of plankton – the minute sea creatures that are at the bottom of the marine food chain, and on which most other forms of sea life depend – which have tiny shells made of calcium carbonate. These are damaged by acid, so whole populations of plankton could be wiped out.
“Things could get really bad,” Prof Roberts says.
It isn’t only sea life that is at threat, he warns.
“Because of the overwhelming influence that the oceans have in the processes that define our planet, these losses not only threaten sea-life, they place human well being itself in jeopardy,” he says.
The good news – if there is any – is that it isn’t yet too late to put a halt to the damage.
Marine reserves where fishing is banned have already proved hugely successful for rebuilding ocean life. They have often resulted in a five-fold increase in marine life within ten years of being set up.
By being a little less greedy and by managing fish stocks better, in other words, we can all benefit. “If we fish less, to allow stocks to recover, we can end up catching more,” Prof Roberts says.
Over-fishing is only one of the problems we need to address, however.
What we need, Prof Roberts says, is a “radical overhaul of our relations with the sea, shifting from overuse and misuse to better stewardship and smarter exploitation. We need to waste less, pollute less, and protect more, so that we can breathe life back into the oceans”.
That is why he has proposed a ‘New Deal’ for the oceans, which includes the following proposals:
• Establish ‘marine reserves’ protected from fishing and other forms of exploitation across one third of all the oceans. This would allow fish stocks to recover – so that fishing fleets would actually be able to catch more, not fewer, fish
• Ban all fishing below a depth of 800metres (half a mile)
• Phase out the most destructive forms of fishing, such as bottom trawls and dredges
• Put in place controls to reduce use of fertilizers and stop them running off into the seas
• Reduce the production of toxic plastics
• Clear up ocean ‘garbage patches’ such as that in the Pacific.
Without effective controls on greenhouse gas emissions, and on consumption, these measures won’t prevent the collapse of marine life in the long-run, says Prof Roberts.
But they might at least help us sustain and protect the seas while we get to grips with those even bigger problems.
Prof Roberts’ exhibition Ocean of Life: How Our Seas Are Changing runs at the Ron Cooke Hub at the University of York from Friday to September 27, and then from Monday, October 1, to Wednesday, October 3, admission free. His book of the same title is published by Allen Lane, priced £25.
What the pictures show
The images on this page today come from Prof Roberts’s exhibition which opens at the University of York’s Sir Ron Cooke Hub from Friday.
They are design to illustrate the nature and scale of what we are doing to the world’s oceans.
The picture above by Cynthia Vanderlip shows a dead albatross chick from Kure atoll in the Hawaiian islands. The chick starved to death after being fed a diet of floating plastic and junk by its parent: junk revealed when the dead chick was cut open.
The corals photographed at Palawan in the Philippines look healthy enough, but the ones that are turning white are already dying because the water is too warm. Three months after this photograph was taken, all the corals pictured were dead, Prof Roberts says.
There have sometimes been abortive attempts to create ‘artificial reefs’ to replace those that are dying – such as the one in the sea off Fort Lauderdale, Florida, that is pictured. It is made of dumped car tyres: and you only have to look closely to notice there is almost no marine life making a home there. The reality is that usually those promoting the idea of artificial reefs have “lots of bulky waste they want to get rid of”, Prof Roberts says.
One image shows green turtles caught in nets that had been set to catch fish in waters off the coast of Brazil.
And while the jellyfish looks beautiful, it is in fact a sign of the damage we are doing to the oceans. It is one of the few types of marine creature that is actually on the increase – and that is because jellyfish thrive on the conditions mankind’s activities are creating in the seas. There are fewer other marine creatures around to eat the young jellyfish; jellyfish actually like the warmer waters; and they even benefit from the agricultural nutrients draining into the seas, because these cause more plankton to grow – and jellyfish eat plankton.
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