Carbon dioxide affecting fish

2012-01-16 07:32

Sydney - Rising human carbon dioxide emissions may be affecting the brains and central nervous systems of sea fish, with serious consequences for their survival, according to research released on Monday.

Carbon dioxide (CO2) concentrations predicted to occur in the ocean by the end of this century will interfere with fishes' ability to hear, smell, turn and evade predators, the research found.

The Australian Research Council's Centre of Excellence for Coral Reef Studies said it had been testing the performance of baby coral fishes in sea water containing higher levels of dissolved CO2 for several years.

"And it is now pretty clear that they sustain significant disruption to their central nervous system, which is likely to impair their chances of survival," said Phillip Munday, a professor who reported the findings.

In a paper published in the journal Nature Climate Change, Munday and his colleagues also detail what they say is world-first evidence that high CO2 levels in sea water disrupts a key brain receptor in fish.

Natural instinct

This causes marked changes in their behaviour and sensory abilities.

"We've found that elevated CO2 in the oceans can directly interfere with fish neurotransmitter functions, which poses a direct and previously unknown threat to sea life," said Munday.

The team began by studying how baby clown and damsel fishes performed alongside their predators in CO2-enriched water.

They found that while the predators were somewhat affected, the baby fish suffered much higher rates of attrition.

"Our early work showed that the sense of smell of baby fish was harmed by higher CO2 in the water, meaning they found it harder to locate a reef to settle on or detect the warning smell of a predator fish," said Munday.

The team then examined whether fishes' sense of hearing - used to locate and home in on reefs at night, and avoid them during the day - was affected.

"The answer is, 'Yes it was'. They were confused and no longer avoided reef sounds during the day. Being attracted to reefs during daylight would make them easy meat for predators."

The research also showed that the fish also tended to lose their natural instinct to turn left or right - an important factor in schooling behaviour.

"All this led us to suspect it wasn't simply damage to their individual senses that was going on, but rather that higher levels of carbon dioxide were affecting their whole central nervous system."

Munday said around 2.3 billion tons of human CO2 emissions dissolve into the world's oceans every year, causing changes in the chemical environment of the water in which fish and other species live.

  • Malcolm - 2012-01-16 09:46

    Just as the combustion engine is largely responsible for the pollution of the earth’s surface, so waterborne sewerage is polluting our oceans, rivers and canals at an alarming rate. Although both these inventions only began in earnest 100 years ago, the damage to our world is staggering and sadly destined for exponential increase. The earth has the capacity to make use of bacteria to rejuvenate sewerage into life-giving soil. For this reason, septic tanks with a liquid soak-away are the only way to keep our waters clean. The addition of bacteria to septic tanks allows for decades of use without the necessity for foreign matter removal, must like that of a steri nappy-bucket. That reminds me, why have we stopped using steri nappy-buckets ... Oh! never mind, that’s another rant.

  • ludlowdj - 2012-01-16 10:47

    Lets forget that climate change is a naturally occurring cycle, lets also forget that the sharp increases in man made CO2 emissions are largely being increased by runaway population growth. man is being allowed to run riot like a virus and is in fact little more than a disease that is slowly killing our planet, current projections indicate that within a hundred years the earth will no longer be able to support man as a life form. The choice is simple correct the problem or have the problem corrected by nature.

      Ernst - 2012-01-16 14:57

      "climate change is a naturally occurring cycle,.." Wrong. The earth's climate system reacts to whatever the dominant forcings are at the time. We are the current dominant force. Presently, we are adding billions of tons of extra greenhouse gasses to the atmosphere at a rapid rate. Do you honestly think that this is not going to have any affect on the earth's climate system? Past climatic changes in earth's history tells us otherwise.

      Ernst - 2012-01-16 15:06

      "man is being allowed to run riot like a virus and is in fact little more than a disease that is..." True. There are way too many people on this planet, but this is not the overriding problem. The problem here is greedy, selfish, corrupt corporations and politicians (fossil feul industry that is heavily subsidized by world goverments) that spend millions of dollars every year to spread lies about climate science and to misinform people about it's validity. Their attacks on scientists and science is a prime example of the lengths they will go to. They control most of the political and media landscape. Look at the current situation in the US. Most of the recently elected republicans deny/ignore manmade global warming. On closer inspection, you will see that these politicians receive substantial financial backing from the oil industry. So essentially, they pull the strings in the world.

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