Ocean acidification leaving fish in the dark

Ocean acidification leaving fish in the dark
Now you see me… Ocean acidification is making things blurry for fish. Credit: Flickr/Mr. T in DC

Increasing carbon dioxide in the world's oceans could hamper fishes' eyesight, slowing their reaction times and leaving them vulnerable to predators or unable to hunt, new research has shown.

Experts say it adds to the existing evidence that will be bad for and possibly fisheries.

Ocean acidification is one of the effects of increasing atmospheric by burning , which is also increasing .

CO2, when absorbed by seawater, is converted to . Since the , ocean pH has decreased by 0.1, corresponding to a 30% increase in ocean acidity.

Previous studies have confirmed that acidification can have a wide variety of impacts on ocean life, including damaging shells and corals and interfering with fishes' sense of smell, with the polar regions particularly vulnerable. Acidification is also known to effect neurotransmitters in fish brains.

The new study, in the Journal of Experimental Biology, shows that increasing CO2 has a direct impact on fish eyes.

The researchers measured the impact of acidification on fish eyes by subjecting damselfish to different amounts of dissolved CO2 and lights flickering at different speeds.

All animals, including humans, can see lights flickering—up to a point. Above a certain speed, flickering lights appear constant. The speed at which flickering light becomes constant varies among species.

The researchers found that at high levels of CO2 fish had trouble resolving high-speed flashes.

Weng-Sun Chung, PhD candidate at University of Queensland and an author on the study, said that although there was no direct evidence that fish have slower with more CO2, the study suggested such effects are likely.

Many fish are dependent on quick reaction times to hunt for food, or escape form predators. If fish are unable to see fast-moving predators or prey, they would be unable to react. Instead, the fish would just see a blur.

Fish that could better cope with higher CO2 would have an advantage over fish with slower reaction times, which could disrupt ecosystems, Chung said.

Winners and losers

Professor Ivan Nagelkerken, an ocean acidification researcher at University of Adelaide, said the study adds to the picture of ocean acidification and its impact on marine life.

"There are a very wide range of impacts of acidification. Most are related to the different senses that fish use."

"We know ocean acidification has a negative effect on the auditory capabilities of fish, and that it interrupts their olfactory capabilities, for example failing to smell optimal habitat and predators. Research has also shown that it effects visual perception."

Professor Nagelkerken said research also shows competition between species may be altered.

"Some fish may get bolder and more aggressive thanks to ocean acidification, and other fishes not. So if you put two species together you will see a shift in aggressiveness and dominance."

Wider ranging impacts might include changes to marine fisheries, and a decline in biodiversity "in favour of more generalist species that can cope with more variable environments".

But Professor Nagelkerken warned it was too early to predict winners and losers.

"We're very far from understanding all of it because there are so many different ecosystems and species."

Explore further

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This story is published courtesy of The Conversation (under Creative Commons-Attribution/No derivatives).
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Citation: Ocean acidification leaving fish in the dark (2014, January 30) retrieved 21 September 2019 from https://phys.org/news/2014-01-ocean-acidification-fish-dark.html
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User comments

Jan 30, 2014
Does this perversity of science never end? There is NO OCEAN ACIDIFICATION.

Carbon, measured in the parts per millions vs. buffering agents measured in the parts per thousands?


You can actually do the math. There isn't enough free carbon in the hydro/atmosphere to impact the ocean pH.

Not to mentions all the ocean basins are lined with gigatons of calcified minerals (the active ingredient in Rolaids and TUMS), like coral and limestone.

Jan 30, 2014
personal conjecture
You can actually do the math. There isn't enough free carbon in the hydro/atmosphere to impact the ocean pH

we will use it as a reference
here is some evidence below:
Prior to industrialization, the concentration of carbon dioxide in the atmosphere was 280 parts per million (ppm). With increased use of fossil fuels, that number is now approaching 400 ppm and the growth rate is accelerating


thanks for your maths/proof shootist

Jan 30, 2014
Does this perversity of the deniers ever end? Ocean acidification is real and can be easily calculated. You take the global CO2 output and the percent of the Ocean's CO2 absorbtion ability, do a calculation and you get the amount of ocean acidification. It's simple chemistry!

Jan 31, 2014
You can actually do the math.

Looks like some people did the math. Oops, looks like you are wrong.

Something most of us learn as youngsters (along with learning how to do math) is that we can be wrong. When lots of people who know far more than you about some subject say something you disagree with, even something you don't like, it should serve as a hint.

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