Rising carbon levels in oceans means smaller fish, researchers say

Oceans absorb much of the carbon dioxide in the Earth's atmosphere, but that may cause fish to be smaller in the future, researchers from the University of Connecticut and other institutions discovered.

"The ocean takes up quite a bit of CO2," Christopher Murray, with the University of Washington, told the National Science Foundation (NSF). "Estimates are that it takes up about one-third to one-half of all CO2 emissions to date. It does a fantastic job of buffering the atmosphere, but the consequence is ocean acidification."

The increased concentration of carbon dioxide leads to smaller fish, the U.S. National Science Foundation-funded researchers said.

Hannes Baumann of UConn told the NSF that researchers thought fish were too mobile and tolerant of rising CO2 levels for this to be a factor.

"Fish are active, robust animals," Murray told NSC. "So when OA was emerging as a major ocean stressor, the assumption was that fish were going to be OK, since they are not like bivalves or sea urchins or other animals showing early sensitivities."

Using current CO2 levels and a worst-case scenario 300 years into the future, the researchers found if fish were fed controlled amounts of food under ideal conditions high CO2 in the seawater would stunt their growth.

A change in the growth of fish can greatly affect fish populations' survival and reproduction, Cynthia Suchman, a program director in NSF's Division of Ocean Sciences, told NSF.