"Farming" fish change strategies depending on CO2 levels: Australian study

CANBERRA, July 10 (Xinhua) -- Fish that farm on seaweeds can change their practices in conditions with high levels of carbon dioxide (CO2), a study has found.

The study, undertaken by researchers from the University of Adelaide and published in the journal Nature Ecology and Evolution on Tuesday, examined damselfish near CO2 volcanic seeps in New Zealand.

Researchers compared the behaviors of damselfish at the volcanic seeps with damselfish in areas with normal levels.

Ivan Nagelkerken, a member of the study from the University of Adelaide's Environment Institute, said that damselfish living with high levels of CO2 changed their cropping practices to ensure a high turnover.

"Climate change and ocean acidification are forecast to decrease species diversity in our oceans but we discovered that some herbivorous fish species might actually increase in number by weeding their territories in such way that their food (turf algae) experiences faster growth rates," Nagelkerken said in a media release on Tuesday.

"Growth rates of their algal food are further accelerated by the elevated CO2, an important nutrient for plants, and as a result, these fish can occupy smaller territories. This means that more fish can live on the same surface area compared to present-day conditions.

"If these results are also applicable to other species, such as some fisheries species, that would be good news for fisheries stocks."

The seeps naturally mimic the ocean CO2 levels expected to occur naturally by the end of the century due to human greenhouse gas emissions.

"This study shows that some populations of fish species might actually benefit from climate change," Sean Connell, another member of the research team, said.

"Nevertheless, there are still strong predictions of declines in other species, likely leading to an overall decrease in species richness."

[ Editor: WPY ]
 

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