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Another Threat to Tuna: Ocean Acidification
http://blogs.scientificamerican.com/extinction-countdown/tuna-ocean-acidification/More acidic oceans could soon start dissolving tuna fish as they swim, long before they make it to consumers’ plates.
This worrying news comes from a study published last month in the Journal of Experimental Marine Biology and Ecology which found that increasing acidification in the Pacific Ocean—a function of climate change—will cause staggering levels of damage to multiple organs in yellowfin tuna (Thunnus albacares) larvae. The injuries, researchers found, will lessen the tunas’ ability to grow to full size and dramatically reduce their rates of survival.
Yellowfin tuna are already heavily overfished in some parts of the world, so this presents one more challenge to their survival.
For this study, researchers from the University of California at Santa Barbara, the Inter-American Tropical Tuna Commission and other organizations collected yellowfin larvae from a commercial aquaculture bloodstock which is normally exposed to pH levels between 8.27 and 7.74. That’s slightly less acidic then neutral water, which has a pH of 7, but also less acidic than many natural conditions. The larvae were taken then taken to a lab and exposed to waters with four different levels of carbon dioxide, which changed the pH. The first tank, considered the control, had a pH of 8.1. The second had a pH of 7.6, which matches global warming projections for the year 2100, while the third had a pH of 7.3, matching projections for the year 2300. A fourth pH level of 6.9 was considered the “lowest projection for the Pacific Ocean.”
(more)
This worrying news comes from a study published last month in the Journal of Experimental Marine Biology and Ecology which found that increasing acidification in the Pacific Ocean—a function of climate change—will cause staggering levels of damage to multiple organs in yellowfin tuna (Thunnus albacares) larvae. The injuries, researchers found, will lessen the tunas’ ability to grow to full size and dramatically reduce their rates of survival.
Yellowfin tuna are already heavily overfished in some parts of the world, so this presents one more challenge to their survival.
For this study, researchers from the University of California at Santa Barbara, the Inter-American Tropical Tuna Commission and other organizations collected yellowfin larvae from a commercial aquaculture bloodstock which is normally exposed to pH levels between 8.27 and 7.74. That’s slightly less acidic then neutral water, which has a pH of 7, but also less acidic than many natural conditions. The larvae were taken then taken to a lab and exposed to waters with four different levels of carbon dioxide, which changed the pH. The first tank, considered the control, had a pH of 8.1. The second had a pH of 7.6, which matches global warming projections for the year 2100, while the third had a pH of 7.3, matching projections for the year 2300. A fourth pH level of 6.9 was considered the “lowest projection for the Pacific Ocean.”
(more)