Lost in an acid sea: a fish's sense of smell

Tha ability of fish to pick up on key chemical cues may be impaired or lost as we pump more carbon into the atmosphere

This article was previously published by the Daily Climate

Acidic ocean water blunts the sense of smell in fish, making them bolder--perhaps recklessly so, according to a new study offering a glimpse of the oceans of the future.

The findings suggest that if greenhouse-gas emissions continue unabated, fish could suffer debilitating behavioral effects. 

"If reef-fish behavior does not adapt to rising [carbon dioxide] levels over coming generations, there could be serious consequences for the structure and function of future reef communities," the authors wrote in the study published in Nature Climate Change

The researchers, however, were surprised to find fish populations near carbon seeps about as diverse and abundant as the fish from normal reefs.

Fish attracted to predators

The researchers studied young fish living near reefs in Papua New Guinea where carbon dioxide venting from volcanic seeps make the water more acidic. Compared to fish from reefs without seeps, the fish in acidic waters were more attracted to their predator's smell, didn't distinguish between different habitats' odours, and were bolder, emerging from shelter at least six times faster after a disturbance. 

The findings build on laboratory and field studies suggesting that increasing ocean acidification will impair fish behavior and gravely affect creatures like coral and shellfish that depend on calcium for a shell. 

The oceans have absorbed about one-third of humanities' greenhouse-gas emissions, buffering the atmosphere. But as oceans absorb the carbon dioxide--some 530 billion tons to date--seawater becomes more acidic.

Ocean acidity stable for 300 million years--until now

The water's pH, a measurement of acidity, remained stable at 8.2 for roughly 300 million years before industrialization. Today it is near 8.1, a drop of 25 percent on the logarithmic scale. 

Seawater pH near the seeps in Papua New Guinea is about 7.8--the same pH that ocean surface waters will reach by 2100, according to climate models assessed by the Intergovernmental Panel on Climate Change. 

"This is the first time people have been able to test what would happen in 100 years," said Danielle Dixson, an assistant professor at Georgia Tech and coauthor of the study, which was led by Australian researchers.

The differences are striking, said Karl Castillo, an assistant professor of marine sciences at the University of North Carolina who was not involved with the research. 

Acidity dulls chemical cues

"This is a strong study," Castillo said. "There's no doubt there is something happening here due to acidification."

Most animals on coral reefs, including fish, rely on chemical cues to know if they should hide or eat or mate with something, Dixson said. Acidity dulls the ability to detect those cues, and the impacts could cascade through the entire reef.

"Not being able to recognize a predator is one of the most dangerous things for any animal," she added. 

Given the behaviour differences, it's not clear why there wasn't more difference in species composition and richness between the seep reefs and the normal reefs, Dixson said. 

Legal protection sought

The study is just the latest example of why ocean acidification needs to be addressed, said Emily Jeffers, a staff attorney with the Center for Biological Diversity. The Center has petitioned the U.S. government to list certain species of corals and reef-dependent fish as endangered to offer some protection from acidification.  

In 2010, the EPA passed a ruling that water impacted by ocean acidification should be listed as impaired under the Clean Water Act. However, no state has listed water as such yet. 

 

Brian Bienkowski is a staff writer for the Daily Climate.

The Daily Climate is an independent, foundation-funded news service covering energy, the environment and climate change.

Comments

2 Comments

Extinction

Apr 21, 2014 at 9:33am

We are in the midst of another great extinction event.

Just as past mass extinction events in the Scientific & Historical documented record.

Acidic Oceans

When carbon dioxide is dissolved in water carbonic acid, H2CO3, is formed.

This prevents Plankton from forming their shells, since they are part of the Base of the Food Chain in the Ocean, if they die most other things above them Die.

Plankton, which are tiny floating plants and animals, form the base of the ocean food chain and produce over half the oxygen in the air we breathe. Many types of plankton, for example, cocoolithophores and foraminifera, form calcium carbonate shells and will be affected by acidification.2 Shell weights of foraminifera are currently 30-35% lower than shells of their counterparts from thousands of years ago, suggesting that acidification may already be negatively affecting these species.3 These organisms play important roles in ocean-atmosphere interactions.

Source...http://centerforoceansolutions.org/climate/impacts/ocean-acidification/d...

These changes are not Linear they are Logarithmic and/or exponential growth in Carbonic Acid within the Oceans.

If the Ocean dies we die pretty simple.

Time to pause from that Starbucks or Timmy's, rethink your Corporate Drone Career, the next iPhone / iPad buy or your plans for the next 10 to 20 years.

Mass Extinctions by their nature cull most species, that means most Humans will not make it, some may but certainly most will not.

The only way to save the Human Species is to immediately take steps to restore the C02 balance and preserve natural biodiversity.

It can not be done within either a Capitalist, Socialist or Communist Governance Model.

aaron green

Apr 22, 2014 at 11:17am

yes....our models show we have 9, maybe 10 years at best, before consequences come home to roost. 20 years ? no way.....