Ocean acidification process. (Image: Hannes Grobe CC-BY-SA-2.5)
Ocean acidification misleads fish larvae
Thursday, April 12, 2018, 03:00 (GMT + 9)
Researchers from the University of Adelaide have found that oceanic larvae will find it harder to reach secure shelters in future acidified oceans, putting fish populations at risk.
These scientists described how barramundi larvae in high CO2 conditions, predicted for the turn of the century, turn away from the ocean noises they would normally be attracted to. They are instead attracted to other sounds – noises produced by the wrong sort of habitats and or ‘white noise’.
“The oceans are far from silent environments; they harbour many noisy animals, for example snapping shrimp and whales and dolphins,” points out project leader Professor Ivan Nagelkerken, from the University of Adelaide’s Environment Institute.
The professor explains that oceanic larvae from quite a few species of fish and invertebrates listen to sounds of coastal ecosystems and use these sounds to guide them from the open ocean, where they hatch, to a sheltered home in shallow waters, where they can spend their juvenile and adult lives.
“Unfortunately the CO2 that humans are pumping into the atmosphere by burning fossil fuels gets absorbed by the ocean and causes acidification, and this causes changes to the behaviour of many marine animals,” the professor adds.
The research compared the activity of barramundi larvae in marine tanks with levels of CO2 that are predicted for the turn of the century against the responses of barramundi larvae in current day CO2 levels.
Professor Nagelkerken stressed they found that while larvae of barramundi are attracted to the sounds of tropical estuaries, larvae raised under future ocean conditions with elevated CO2 were deterred by these natural sounds, clarifying that under elevated CO2, larval barramundi were attracted to the wrong sounds.
Professor Sean Connell, from the University’s Southern Seas Ecology Laboratories, said that if ocean acidification causes larvae to be deterred to the sounds of their habitats, and attracts them to irrelevant sounds, they could end up in the wrong habitat or in places where they cannot survive.
“Fewer larvae are arriving in coastal ecosystems, estuaries and rivers could result in smaller population sizes and, in the case of commercial species like barramundi, this could have a significant impact on fisheries, whether it be commercial or recreational,” Professor Connell explained.
The research findings were published in the Nature journal Scientific Reports.