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April 29, 2015

Northern Rock Sole Larvae Appear Resilient to Some Effects of Ocean Acidification

larval northern rock sole

A study done by NOAA Fisheries in collaboration with NOAA’s Pacific Marine Environmental Lab and Oregon State University’s Hatfield Marine Science Center was published this week in the ICES Journal of Marine Science testing how newly hatched northern rock sole growth and development could respond to a more acidic ocean, an ocean with higher levels of carbon dioxide (CO2) and lower pH.

Bottom line: Reduced pH levels predicted for ocean acidification did not hamper growth and development of young northern rock sole. However, the authors caution that there are other potential impacts to northern rock sole that have yet to be examined as ocean acidification may alter the abundance of the tiny crustaceans that small rock sole feed upon. In addition, elevated CO2 levels have been shown to disrupt feeding and migration behaviors in other fish species.

More About Ocean Acidification

The Earth’s oceans play a key role in helping to regulate climate. They are currently absorbing some of the excess CO2 from the atmosphere. With rising levels of CO2, the chemistry of the ocean changes.The level of pH in oceanic waters declines making the water more acidic.

CO2 level

% change
of pH
Current/Ambient 370 8.1  
20-30 year prediction 480 8.0 58%
100 year prediction 700 7.85 151%
Physiological testing 1250 7.6 298%
*Note: Changes in ocean acidity are measured by pH. pH is measured on a scale from 0 to 14. Whenever pH changes (i.e, increases or decreases by one point) the change represents a 10-fold change. For example, a pH of 7 is ten times more acidic than a pH of 8 and 100 times (10 times 10) more acidic than a pH of 9.

A more acidic ocean affects shell-producing creatures like crabs, lobsters, oysters and clams, but in different ways. Some studies have shown that crabs and lobster shell-building may actually increase, while shells of clams, snails, and oysters may dissolve under conditions of elevated CO2 in the water. The increases in CO2 levels can also have a range of different effects on fishes and other non-shell forming animals. So, scientists and fishermen are concerned about the impacts of increasingly acidic oceans on commercial fishery species.

How Did Scientists Study This?

Scientists keep northern rock sole and several other commercially and recreationally important Alaskan fish species at the Alaska Fisheries Science Center laboratory in Newport, Oregon. Offspring from these fish are used to examine potential environmental and climate effects on these species.

In multiple experiments, the researchers reared northern rock sole eggs and larvae in the laboratory at current and elevated CO2 levels. The researchers found only minor effects to growth and development during the first 28 days. Growth rates of larvae between 28 and 56 days old were reduced at high CO2 levels, but this effect was only observed at CO2 levels above those predicted to occur in Alaskan surface waters by the end of this century. While these findings suggest good news for the long-term health of the northern rock sole population in the ocean, more research is needed to fully understand how a more acidic environment could affect these fish and the things they eat. Understanding these relationships of how increasing CO2 and declining pH levels will impact northern rock sole and other harvested populations in the wild enables us to better manage commercial and recreational fisheries to ensure the sustainability of these important fish stocks.  

Other Related Studies From AFSC Scientists



For more information please contact Marjorie Mooney-Seus,
206-526-4348 (office), 774-392-4865 (cell)

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