NSW releases shark attack proposals - ABC News
The New South Wales Government has released a number of new proposals to prevent shark attacks, as it defends itself against claims it is failing to protect swimmers after three attacks in Sydney in as many weeks.
The measures include a new shark tagging program, the use of GPS to monitor shark nets and a list of shark attacks by beach since 1900.
The Government is also considering upgrading shark fishing gear and researching shark movements, attacks and population trends to try to identify hotspots and high-risk periods.
The proposals are part of the first review of the long-standing shark net program since 1972. They also include publishing an annual report about the nets' performance.
Primary Industries Minister Ian Macdonald says the Government will also consult with surf lifesavers.
'The Government in the past has provided a number of jet skis to surf lifesavers that have helped them monitor and deter sharks and we'll be discussing these on Thursday,' he said.
The Opposition says the Government has not done enough to protect swimmers and surfers. It says shark nets are deteriorating, the shark fishing quota should be increased and beaches need more aerial patrols.
But Mr Macdonald says aerial patrols do not spot sharks at dawn and dusk, the high-risk periods when the three latest shark attacks occurred. He says the patrols sometimes confuse big fish with sharks.
The Minister also says only 4.2 per cent of sharks caught in the fishing quota are dangerous.
In the latest shark attack, 15-year-old Andrew Lindop was bitten on the leg while surfing with his father, a veteran lifesaver, at Sydney's Avalon Beach at dawn on Sunday.
The boy is recovering in a stable condition in hospital after being rescued by his father.
This year's first Sydney victim, elite Navy diver Paul de Gelder, lost a hand and a leg after being attacked by a bull shark at dawn off Garden Island in Sydney Harbour on February 11.
The following day, surfer Glenn Orgias was mauled by a great white shark at the southern end of Bondi Beach at dusk.
His hand was hanging off his wrist by a three-centimetre piece of skin but doctors have managed to save it in what they have described as a 'minor miracle'.
The proposals will be made open to public consultation next month.
- Sent using Google Toolbar"
* THE BULL SHARK IS THE MOST DANGEROUS SHARK THAT MANKIND * * HAS EVER MET. Go to the #1 most dangerous shark page to see why *
Monday, December 6, 2010
Mexican Shark Decline
Shark Diver Magazine Blog
Holbox Island was once a shark fisherman's paradise. Everyone on the island used to fish for sharks. In the 50's and 60's, they would sell the shark oil, in the 70's, it was their skin and oil, the vendors were after, in the mid 80's and above, it was the fins. Now the vendors want the entire shark. The 'coyote', that is the name of the guy who purchases sharks on the island. He takes the sharks and the sharks ultimately end up getting cut up and sold to different countries in Florida. Nice! Of course the islanders are not fishing for sharks anymore. They decimated the entire population of local and migratory sharks, to the point that the island can only sustain 3 to 4 shark fishermen now.
- Sent using Google Toolbar"
Holbox Island was once a shark fisherman's paradise. Everyone on the island used to fish for sharks. In the 50's and 60's, they would sell the shark oil, in the 70's, it was their skin and oil, the vendors were after, in the mid 80's and above, it was the fins. Now the vendors want the entire shark. The 'coyote', that is the name of the guy who purchases sharks on the island. He takes the sharks and the sharks ultimately end up getting cut up and sold to different countries in Florida. Nice! Of course the islanders are not fishing for sharks anymore. They decimated the entire population of local and migratory sharks, to the point that the island can only sustain 3 to 4 shark fishermen now.
- Sent using Google Toolbar"
Saturday, December 4, 2010
Thursday, December 2, 2010
Why Study Shark Attacks
Because they provide a glimpse - a window - into the world of sharks and their behaviors. By understanding when and why sharks sometimes bite humans it is possible to lessen the likelihood of such accidents. Humans are familiar with predators found on land; we know enough not to walk into a pride of lions and we don't try to pet a growling dog that is baring its teeth. Similarly, we need to recognize and avoid potentially dangerous situations in the water. The individual case histories provide insights about specific geographical areas and their indigenous species of sharks. However, when all known case histories are examined, much is revealed about species behavior, and specific patterns emerge.
Most of the incidents in the Global Shark Attack File have nothing to do with predation. Some incidents are motivated by displacement or are a territorial behavior, or when the shark feels threatened; still others are the result of the shark responding to sensory predatory input (i.e., overwhelmed by the presence of many fishes) and environmental conditions (murky water) which may cause the animal to respond in a reflexive response to stimuli. Sharks also exhibit curiosity and may investigate unknown or unfamiliar objects; they learn by exploring their environment, and - lacking hands - they use their mouths and teeth to examine unfamiliar objects.
A very small percentage of shark species, about two dozen, are considered potentially dangerous to humans because of their size and dentition. Yet each year, for every human killed by a shark, our species slaughters more than 10 million sharks - about 100 million sharks last year. We are stripping the world's oceans of one of its most valuable predators - animals that play a critical role in maintaining the health of the world's oceans. An unreasonable fear of sharks has been implanted in our minds by the hype that surrounds the rare shark attack and by movies that exploit our primal fears. It is the mission of the Global Shark Attack File to present facts about these events, thus enabling them to be put in perspective. Sharks are necessary and vital to the ocean ecosystem. Without sharks our planet's ocean could eventually become a watery graveyard, with little sustainable life. This is not the legacy the Global Shark Attack File and the Shark Research Institute wishes to leave our children and our children's children.
The Global Shark Attack File was created to provide medical personnel, shark behaviorists, lifesavers, and the media with meaningful information resulting from the scientific forensic examination of shark accidents. Whenever possible, GSAF investigators conduct personal interviews with patients and witnesses, medical personnel and other professionals, and conduct examinations of the incident site. Weather and sea conditions and environmental data are evaluated in an attempt to identify factors that contributed to the incident.
Early on, we became aware that the word "attack" was usually a misnomer. An "attack" by a shark is an extremely rare event, even less likely than statistics suggest. When a shark bites a surfboard, leaving the surfer unharmed, it was historically recorded as an "attack". Collisions between humans and sharks in low visibility water were also recorded as "attacks".
When a shark grabs a person by the hand/wrist and tows them along the surface, tosses a surfboard (or a Frisbee as in case 1968.08.24) it is probably "play behavior", not aggression. How can case 1971.04.11 which the swimmer was repeatedly bitten by a large shark and case 1985.01.04 in which the diver's injury necessitated a Band-aid be compared? It is akin to comparing a head-on high-speed vehicular collision with a shopping cart ding on the door of a parked car. Global Shark Attack File believes the only way to sort fact from hype is by forensic examination of each incident.
Although incidents that occur in remote areas may go unrecorded, the Global Shark Attack File is a compilation of a number of data sources, and we have a team of qualified researchers throughout the world that actively investigate these incidents. One of our objectives is to provide a clear picture of the actual threat presented by sharks to humans. In this regard, we remind our visitors that more people drown in a single year in the United States than have been killed by sharks throughout the entire world in the last two centuries.
Most of the incidents in the Global Shark Attack File have nothing to do with predation. Some incidents are motivated by displacement or are a territorial behavior, or when the shark feels threatened; still others are the result of the shark responding to sensory predatory input (i.e., overwhelmed by the presence of many fishes) and environmental conditions (murky water) which may cause the animal to respond in a reflexive response to stimuli. Sharks also exhibit curiosity and may investigate unknown or unfamiliar objects; they learn by exploring their environment, and - lacking hands - they use their mouths and teeth to examine unfamiliar objects. A very small percentage of shark species, about two dozen, are considered potentially dangerous to humans because of their size and dentition. Yet each year, for every human killed by a shark, our species slaughters more than 10 million sharks - about 100 million sharks last year. We are stripping the world's oceans of one of its most valuable predators - animals that play a critical role in maintaining the health of the world's oceans. An unreasonable fear of sharks has been implanted in our minds by the hype that surrounds the rare shark attack and by movies that exploit our primal fears. It is the mission of the Global Shark Attack File to present facts about these events, thus enabling them to be put in perspective. Sharks are necessary and vital to the ocean ecosystem. Without sharks our planet's ocean could eventually become a watery graveyard, with little sustainable life. This is not the legacy the Global Shark Attack File and the Shark Research Institute wishes to leave our children and our children's children.
The Global Shark Attack File was created to provide medical personnel, shark behaviorists, lifesavers, and the media with meaningful information resulting from the scientific forensic examination of shark accidents. Whenever possible, GSAF investigators conduct personal interviews with patients and witnesses, medical personnel and other professionals, and conduct examinations of the incident site. Weather and sea conditions and environmental data are evaluated in an attempt to identify factors that contributed to the incident.
Early on, we became aware that the word "attack" was usually a misnomer. An "attack" by a shark is an extremely rare event, even less likely than statistics suggest. When a shark bites a surfboard, leaving the surfer unharmed, it was historically recorded as an "attack". Collisions between humans and sharks in low visibility water were also recorded as "attacks".
When a shark grabs a person by the hand/wrist and tows them along the surface, tosses a surfboard (or a Frisbee as in case 1968.08.24) it is probably "play behavior", not aggression. How can case 1971.04.11 which the swimmer was repeatedly bitten by a large shark and case 1985.01.04 in which the diver's injury necessitated a Band-aid be compared? It is akin to comparing a head-on high-speed vehicular collision with a shopping cart ding on the door of a parked car. Global Shark Attack File believes the only way to sort fact from hype is by forensic examination of each incident.
Although incidents that occur in remote areas may go unrecorded, the Global Shark Attack File is a compilation of a number of data sources, and we have a team of qualified researchers throughout the world that actively investigate these incidents. One of our objectives is to provide a clear picture of the actual threat presented by sharks to humans. In this regard, we remind our visitors that more people drown in a single year in the United States than have been killed by sharks throughout the entire world in the last two centuries.
Source: Global Shark Attack File
Website: http://www.sharkattackfile.net
How to Avoid Shark Attacks
Recommendations to avoid and survive a shark attack:
"Seek advice of local people before swimming, surfing or diving in areas where shark attacks have occurred.
Reason: Locals know the area.
Remain aware of your surroundings and the behavior of marine life nearby.
Reason: Their actions may alert you to the presence of marine predators.
If you suddenly become uneasy, leave the water immediately.
Reason: Your instincts may be providing a warning of impending danger.
Do not harass or touch any shark, even a small one.
Reason: Any shark is capable of inflicting injury.
If swimming or surfing do not enter the water when sharks are present, and leave the water the water slowly and quietly if they are sighted or you are requested to do so by a lifeguard.
Reason: If sharks are in the immediate area, the risk of injury is increased.
Do not swim, surf or dive alone
Reason: Sharks may be more likely to bite solitary individuals, and if you are injured there is nobody to help you.
Do not stray far from shore
Reason: You are farther from assistance, should you need it.
Avoid swimming at night.
Reason: There is strong evidence to suggest that sharks move in closer to a land mass (island or shore) following sunset.
Avoid murky or turbid water.
Reason: Some species of sharks hunt in murky or turbid water, others may bite because of stress, and others may simply fail to recognize an object and bite to find out what it is. It is also difficult to defend yourself from something you cannot see.
Avoid swimming close to river mouths.
Reason: Freshwater plankton dies and attracts fish, some species of fish spawn at river mouths, and carcasses of dead animals are carried downstream. All these conditions attract predators such as sharks.
Be cautious when swimming in the breakers.
Reason: Sharks may become stressed due to the low visibility and sudden presence of humans..
Don't swim close to sandbars.
Reason: Any natural structure attracts a variety of marine animals and may be a feeding area for sharks.
Be cautious crossing channels between sandbars or on the edge of steep drop offs.
Reason: These are often feeding areas for sharks.
Avoid swimming or surfing near jetties.
Reason: These are often feeding areas for sharks.
Do not corner a shark or cut off its path to open water.
Reason: It may feel threatened and react defensively.
Avoid swimming in areas where birds are diving into the water.
Reason: Diving birds indicate schools of fish are in the area and the likelihood that sharks in the area is increased.
If schools of fish are milling nearby, do not attempt to chase them from the area.
Reason: Frightened, darting fish create distinctive sounds that are very attractive to sharks.
If baitfish are leaping at or above the surface, leave the water immediately.
Reason: Predator fish, possibly sharks, are feeding on the baitfish.
If spearfishing or collecting shellfish, do not attach your catch to a stringer at your waist, and stay alert when removing a fish from your spear. If wade-fishing, do not carry bait on your person.
Reason: A shark attempting to snatch your catch or the bait, could inadvertently injure you.
If spearfishing, change your location frequently.
Reason: The vibrations of speared fish attract sharks.
Avoid areas where any type of fishing activity is taking place or offal is dumped into the sea.
Reason: These areas attract sharks.
The presence of porpoises and dolphins may indicate sharks are hunting in the area.
Reason: These species often feed with sharks.
Leave the water when pods of dolphin cluster or head inshore
Reason: This behavior is often associated with the proximity of sharks.
Avoid swimming, surfing or diving in the vicinity of pinniped haul-outs or rookeries.
Reason: These animals are the prey of large sharks, including white sharks.
Avoid high contrast swim suits
Reason: It is thought sharks are attracted to high-contrast objects.
Refrain from excess splashing or making quick, abrupt movements in the water.
Reason: It suggests an animal in distress.
Do not swim with dogs or horses.
Reason: Their splashing may attract a predator.
If a shark approaches uncomfortably close, keep it at bay with your speargun or a shark “billy”.
Do not attempt to spear the shark unless you think an attack is imminent.
Reason: The shark may simply be curious, but if you respond with aggression the shark may react in the same way.
If you are bitten by a shark and you are wearing a wetsuit, don't remove the wetsuit except to control arterial bleeding.
Reason: A wetsuit acts as a pressure bandage and restricts the loss of blood.
Take both a CPR course and an advanced first aid course.
Reason: Many fatalities in the GSAF file could have been avoided if arterial bleeding had been recognized and stopped, and basic life support provided until professional medical assistance arrived. The life you save could be your own or that of a loved one.
"Seek advice of local people before swimming, surfing or diving in areas where shark attacks have occurred.
Reason: Locals know the area.
Remain aware of your surroundings and the behavior of marine life nearby.
Reason: Their actions may alert you to the presence of marine predators.
If you suddenly become uneasy, leave the water immediately.
Reason: Your instincts may be providing a warning of impending danger.
Do not harass or touch any shark, even a small one.
Reason: Any shark is capable of inflicting injury.
If swimming or surfing do not enter the water when sharks are present, and leave the water the water slowly and quietly if they are sighted or you are requested to do so by a lifeguard.
Reason: If sharks are in the immediate area, the risk of injury is increased.
Do not swim, surf or dive alone
Reason: Sharks may be more likely to bite solitary individuals, and if you are injured there is nobody to help you.
Do not stray far from shore
Reason: You are farther from assistance, should you need it.
Avoid swimming at night.
Reason: There is strong evidence to suggest that sharks move in closer to a land mass (island or shore) following sunset.
Avoid murky or turbid water.
Reason: Some species of sharks hunt in murky or turbid water, others may bite because of stress, and others may simply fail to recognize an object and bite to find out what it is. It is also difficult to defend yourself from something you cannot see.
Avoid swimming close to river mouths.
Reason: Freshwater plankton dies and attracts fish, some species of fish spawn at river mouths, and carcasses of dead animals are carried downstream. All these conditions attract predators such as sharks.
Be cautious when swimming in the breakers.
Reason: Sharks may become stressed due to the low visibility and sudden presence of humans..
Don't swim close to sandbars.
Reason: Any natural structure attracts a variety of marine animals and may be a feeding area for sharks.
Be cautious crossing channels between sandbars or on the edge of steep drop offs.
Reason: These are often feeding areas for sharks.
Avoid swimming or surfing near jetties.
Reason: These are often feeding areas for sharks.
Do not corner a shark or cut off its path to open water.
Reason: It may feel threatened and react defensively.
Avoid swimming in areas where birds are diving into the water.
Reason: Diving birds indicate schools of fish are in the area and the likelihood that sharks in the area is increased.
If schools of fish are milling nearby, do not attempt to chase them from the area.
Reason: Frightened, darting fish create distinctive sounds that are very attractive to sharks.
If baitfish are leaping at or above the surface, leave the water immediately.
Reason: Predator fish, possibly sharks, are feeding on the baitfish.
If spearfishing or collecting shellfish, do not attach your catch to a stringer at your waist, and stay alert when removing a fish from your spear. If wade-fishing, do not carry bait on your person.
Reason: A shark attempting to snatch your catch or the bait, could inadvertently injure you.
If spearfishing, change your location frequently.
Reason: The vibrations of speared fish attract sharks.
Avoid areas where any type of fishing activity is taking place or offal is dumped into the sea.
Reason: These areas attract sharks.
The presence of porpoises and dolphins may indicate sharks are hunting in the area.
Reason: These species often feed with sharks.
Leave the water when pods of dolphin cluster or head inshore
Reason: This behavior is often associated with the proximity of sharks.
Avoid swimming, surfing or diving in the vicinity of pinniped haul-outs or rookeries.
Reason: These animals are the prey of large sharks, including white sharks.
Avoid high contrast swim suits
Reason: It is thought sharks are attracted to high-contrast objects.
Refrain from excess splashing or making quick, abrupt movements in the water.
Reason: It suggests an animal in distress.
Do not swim with dogs or horses.
Reason: Their splashing may attract a predator.
If a shark approaches uncomfortably close, keep it at bay with your speargun or a shark “billy”.
Do not attempt to spear the shark unless you think an attack is imminent.
Reason: The shark may simply be curious, but if you respond with aggression the shark may react in the same way.
If you are bitten by a shark and you are wearing a wetsuit, don't remove the wetsuit except to control arterial bleeding.
Reason: A wetsuit acts as a pressure bandage and restricts the loss of blood.
Take both a CPR course and an advanced first aid course.
Reason: Many fatalities in the GSAF file could have been avoided if arterial bleeding had been recognized and stopped, and basic life support provided until professional medical assistance arrived. The life you save could be your own or that of a loved one.
Police dog braves shark infested river
Anything to do with Bull Sharks is big news on Queenslands Gold Coast (Australia), even if it has nothing to really do with sharks at all:
Police dog braves shark infested river to catch criminal | Dream Dogs Stud Dogs News
by Mark Glenning on November 26, 2010
In an amazing climax to a police chase, a fearless police dog sank his teeth into a fleeing criminal and refused to let go, even though they were swimming in a shark infested stretch of water.
The Hollywood style pursuit began at 3 AM in Ashmore Plaza, on the Gold Coast, when police were called to an incident involving a break-in at a shop. Officers arrived to disturb two men, one of whom fled on foot whilst the other leapt into a car and drove off. One officer opened fire on the vehicle, but the thief made good his escape.
Half an hour later, police spotted the vehicle again and gave chase. The driver crashed into a roundabout, blowing out a tyre before reversing into a police car. He decided to make a run for it, and officers released a police dog – a police dog who had no intention of letting the criminal evade him.
After a chase through the backstreets, the dog caught up with the fleeing criminal and sank its teeth into his leg, refusing to let its quarry go. In desperation, the thief tried to swim across the Nerang River, which is renowned as a hotspot for Bull sharks, which are notorious for attacking humans and whose bite is often mistaken for a Great White – the shark from the film Jaws.
As the wanted man was struggling to cross the river, with the dog still attached, police commandeered a passing jet ski, and headed out into the water to make an arrest.
Two men aged 33 and 30 are now in custody.
- Sent using Google Toolbar"
Police dog braves shark infested river to catch criminal | Dream Dogs Stud Dogs News
by Mark Glenning on November 26, 2010
In an amazing climax to a police chase, a fearless police dog sank his teeth into a fleeing criminal and refused to let go, even though they were swimming in a shark infested stretch of water.
The Hollywood style pursuit began at 3 AM in Ashmore Plaza, on the Gold Coast, when police were called to an incident involving a break-in at a shop. Officers arrived to disturb two men, one of whom fled on foot whilst the other leapt into a car and drove off. One officer opened fire on the vehicle, but the thief made good his escape.
Half an hour later, police spotted the vehicle again and gave chase. The driver crashed into a roundabout, blowing out a tyre before reversing into a police car. He decided to make a run for it, and officers released a police dog – a police dog who had no intention of letting the criminal evade him.
After a chase through the backstreets, the dog caught up with the fleeing criminal and sank its teeth into his leg, refusing to let its quarry go. In desperation, the thief tried to swim across the Nerang River, which is renowned as a hotspot for Bull sharks, which are notorious for attacking humans and whose bite is often mistaken for a Great White – the shark from the film Jaws.
As the wanted man was struggling to cross the river, with the dog still attached, police commandeered a passing jet ski, and headed out into the water to make an arrest.
Two men aged 33 and 30 are now in custody.
- Sent using Google Toolbar"
Wednesday, December 1, 2010
Is the Ocean Dying?
Scientists fear mass extinction as oceans choke - ABC News
Low oxygen levels, which have been found along south-eastern Australia, are known to increase stress on fish. (Reuters: Ho New)
Australian scientists fear the planet is on the brink of another mass extinction as ocean dead zones continue to grow in size and number.
More than 400 ocean dead zones - areas so low in oxygen that sea life cannot survive - have been reported by oceanographers around the world between 2000 and 2008.
That is compared with 300 in the 1990s and 120 in the 1980s.
Professor Ove Hoegh-Guldberg, of the ARC Centre of Excellence for Coral Reef Studies (CoECRS) and from the University of Queensland, says there is growing evidence that declining oxygen levels in the ocean have played a major role in at least four of the planet's five mass extinctions.
'Until recently the best hypothesis for them was a meteor strike,' he said.
'So 65 million years ago they've got very good evidence ... all the dinosaurs died because of smoke and stuff in the atmosphere from a meteor strike.
'But with the four other mass extinction events, one of the best explanations now is that these periods were preceded by an increase of volcanic activity, and that volcanic activity caused a change in ocean circulation.
'Just as we are seeing at a smaller scale today, huge parts of the ocean became anoxic at depth.
'The consequence of that is that you had increased amounts of rotten egg gas, hydrogen sulfide, going up into the atmosphere, and that is thought to be what may have caused some of these other extinction events.'
Professor Hoegh-Guldberg says up to 90 per cent of life has perished in previous mass extinctions and that a similar loss of life could occur in the next 100 years.
'We're already having another mass extinction due to humans wiping out life and so on, but it looks like it could get as high as those previous events,' he said.
'So it's the combination of this alteration to coastlines, climate change and everything, that has a lot of us worried we are going to drive the sixth extinction event and it will happen over the next 100 years because we are interfering with the things that keep species alive.
'Ocean ecosystems are in a lot of trouble and it all bears the hallmarks of human interference.
'We are changing the way the Earth's oceans work, shifting them to entirely new states, which we have not seen before.'
He says while it is impossible to predict the future, in a century from now the world will be vastly different.
'A world without the Great Barrier Reef, where you don't have the pleasure of going to see wild places any more,' he said.
'We might be able to struggle on with much lower population densities, but ultimately it won't be the world we have today.
'The idea of walking in the Daintree will be a forgotten concept because these changes have occurred.'
Hearts and lungs
Scientists say ocean dead zones, which vary in size from one square kilometre to 70,000 square kilometres, have been found all over the world.
Particular hotspots include the Gulf of Mexico, off Namibia in the South Atlantic, in the Bay of Bengal, in the Baltic, the Black Sea, the tropical South Pacific, off China and south-eastern Australia.
'We're seeing an expansion of areas of the ocean which are very low in oxygen and also very low in nutrients,' Professor Hoegh-Guldberg said.
'Climate change is driving changes to water circulation - so winds, strange weather patterns, have a consequence for how the ocean turns over and aerates and so on, and it's the winds which are delivering a lot of organic compounds into the deep sea.
'At the same time we are putting a lot of fertiliser off coastlines, those sorts of things are incubating these deep water anoxic zones.
'So it's the combination of those two things that are having a big change on how the ocean works.'
He says organic matter building up in the sea is a huge problem.
'You get enormous amounts of organic carbon building up at depth, bacteria then likes to break down that organic matter and bacteria uses up the oxygen,' he said.
'So then what you get is a substantial drop in oxygen - that then has the consequences for fishers, for the productivity of coastlines and so on.'
Destructive path
Associate Professor Mark McCormick, also of CoECRS and from James Cook University, says low oxygen levels increase stress on fish.
'We know from our recent work that increases in stress result in deformities, leading to poorer survival of fish larvae,' he said.
'It has also been found they can cause fish to have smaller ovaries, produce fewer eggs, so larvae are also smaller and less likely to survive.'
Professor Hoegh-Guldberg says the problem is not as significant in Australia as other parts of the world, but that it is heading along the same, destructive path.
'We've been altering coastal areas, delivering nutrients into the ocean, and of course you see the Great Barrier Reef, which has been quite damaged due to nutrient run-off,' he said.
'But the point is that our activities on land have a big influence on what goes on in the oceans and now we are starting to reap the harvest of those changes.'
He says the heart and lungs of the planet are being tampered with.
'We are starting to see changes in the ocean's ability to produce oxygen and to produce food and produce all of the ecosystem's services that are so important to not only us, but all of the other organisms on the planet,' he said.
'It's mucking around with the heart and lungs of the planet - that's essentially what the oceans are, a huge respiratory system.
'We damage them, the consequences could be very serious.'
Professor Hoegh-Guldberg says while the dead zones may only exist in pockets of ocean today, it will affect a far greater area in the future unless steps are taken to reduce the impact of human activities on the world's oceans and their life.
- Sent using Google Toolbar"
Low oxygen levels, which have been found along south-eastern Australia, are known to increase stress on fish. (Reuters: Ho New)
Australian scientists fear the planet is on the brink of another mass extinction as ocean dead zones continue to grow in size and number.
More than 400 ocean dead zones - areas so low in oxygen that sea life cannot survive - have been reported by oceanographers around the world between 2000 and 2008.
That is compared with 300 in the 1990s and 120 in the 1980s.
Professor Ove Hoegh-Guldberg, of the ARC Centre of Excellence for Coral Reef Studies (CoECRS) and from the University of Queensland, says there is growing evidence that declining oxygen levels in the ocean have played a major role in at least four of the planet's five mass extinctions.
'Until recently the best hypothesis for them was a meteor strike,' he said.
'So 65 million years ago they've got very good evidence ... all the dinosaurs died because of smoke and stuff in the atmosphere from a meteor strike.
'But with the four other mass extinction events, one of the best explanations now is that these periods were preceded by an increase of volcanic activity, and that volcanic activity caused a change in ocean circulation.
'Just as we are seeing at a smaller scale today, huge parts of the ocean became anoxic at depth.
'The consequence of that is that you had increased amounts of rotten egg gas, hydrogen sulfide, going up into the atmosphere, and that is thought to be what may have caused some of these other extinction events.'
Professor Hoegh-Guldberg says up to 90 per cent of life has perished in previous mass extinctions and that a similar loss of life could occur in the next 100 years.
'We're already having another mass extinction due to humans wiping out life and so on, but it looks like it could get as high as those previous events,' he said.
'So it's the combination of this alteration to coastlines, climate change and everything, that has a lot of us worried we are going to drive the sixth extinction event and it will happen over the next 100 years because we are interfering with the things that keep species alive.
'Ocean ecosystems are in a lot of trouble and it all bears the hallmarks of human interference.
'We are changing the way the Earth's oceans work, shifting them to entirely new states, which we have not seen before.'
He says while it is impossible to predict the future, in a century from now the world will be vastly different.
'A world without the Great Barrier Reef, where you don't have the pleasure of going to see wild places any more,' he said.
'We might be able to struggle on with much lower population densities, but ultimately it won't be the world we have today.
'The idea of walking in the Daintree will be a forgotten concept because these changes have occurred.'
Hearts and lungs
Scientists say ocean dead zones, which vary in size from one square kilometre to 70,000 square kilometres, have been found all over the world.
Particular hotspots include the Gulf of Mexico, off Namibia in the South Atlantic, in the Bay of Bengal, in the Baltic, the Black Sea, the tropical South Pacific, off China and south-eastern Australia.
'We're seeing an expansion of areas of the ocean which are very low in oxygen and also very low in nutrients,' Professor Hoegh-Guldberg said.
'Climate change is driving changes to water circulation - so winds, strange weather patterns, have a consequence for how the ocean turns over and aerates and so on, and it's the winds which are delivering a lot of organic compounds into the deep sea.
'At the same time we are putting a lot of fertiliser off coastlines, those sorts of things are incubating these deep water anoxic zones.
'So it's the combination of those two things that are having a big change on how the ocean works.'
He says organic matter building up in the sea is a huge problem.
'You get enormous amounts of organic carbon building up at depth, bacteria then likes to break down that organic matter and bacteria uses up the oxygen,' he said.
'So then what you get is a substantial drop in oxygen - that then has the consequences for fishers, for the productivity of coastlines and so on.'
Destructive path
Associate Professor Mark McCormick, also of CoECRS and from James Cook University, says low oxygen levels increase stress on fish.
'We know from our recent work that increases in stress result in deformities, leading to poorer survival of fish larvae,' he said.
'It has also been found they can cause fish to have smaller ovaries, produce fewer eggs, so larvae are also smaller and less likely to survive.'
Professor Hoegh-Guldberg says the problem is not as significant in Australia as other parts of the world, but that it is heading along the same, destructive path.
'We've been altering coastal areas, delivering nutrients into the ocean, and of course you see the Great Barrier Reef, which has been quite damaged due to nutrient run-off,' he said.
'But the point is that our activities on land have a big influence on what goes on in the oceans and now we are starting to reap the harvest of those changes.'
He says the heart and lungs of the planet are being tampered with.
'We are starting to see changes in the ocean's ability to produce oxygen and to produce food and produce all of the ecosystem's services that are so important to not only us, but all of the other organisms on the planet,' he said.
'It's mucking around with the heart and lungs of the planet - that's essentially what the oceans are, a huge respiratory system.
'We damage them, the consequences could be very serious.'
Professor Hoegh-Guldberg says while the dead zones may only exist in pockets of ocean today, it will affect a far greater area in the future unless steps are taken to reduce the impact of human activities on the world's oceans and their life.
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