Ocean acidification

Posted on EPOCA: 15 Jul 2011 — Congressional Natural Resources Committee Report highlights Pacific Northwest shellfish industry


The smallest organisms in the ocean have some of the greatest influence on our lives. Single celled plants called phytoplankton produce one half of the oxygen we breathe. At the surface of the ocean, there can be more than a million of these tiny suspended plants in each liter of water. Phytoplankon support nearly all life in the ocean. Rays from the sun illuminate the sea and these plants use nutrients from the water to turn this solar energy into food. But we are now altering the fundamental characteristics of the planet, including the ocean. By producing record carbon dioxide emissions, we have acidified the ocean; the home of these incredibly important organisms.

The oceans absorb almost a third of the carbon dioxide we release into the atmosphere every year and this is changing the chemistry of the sea in ways we are just beginning to understand. This process is called ocean acidification. The acidity of the ocean has increased 30% since the beginning of the Industrial Revolution, a rate faster than anything previously experienced over the last 55 million years of Earth’s history. How do we know ocean acidification is happening? We know because of long-term measurements by scientists. Below is a graph showing carbon dioxide in the air, ocean carbon dioxide absorption, and ocean acidification near the Hawaiian Islands over recent decades. Continued monitoring (via NOAA and other federal agencies) of the ocean is imperative to predict ecosystem responses, and develop management strategies (Ocean Acidification Task Force) to adapt to the consequences of ocean acidification.

Ocean acidification will likely impact biodiversity. Numerous plant and animal species in the sea have calcium carbonate skeletons or shells and some are already being corroded by small changes in acidity.Many of these sensitive species are of great economic, cultural, and biological importance, including coral reefs, oysters and crabs, and primary producers like algae and sea lettuce that are eaten by fish. A recent preliminary report from the International Programme on the State of the Ocean (IPSO) examined the combined impact of all of the stressors currently affecting the oceans and listed ocean acidification, along with ocean warming and anoxia (lack of oxygen that causes “dead zones“), as the top historical factors contributing to mass extinctions.  The panel warns that the combination of these factors will inevitably lead to mass extinctions if conditions are not mitigated.

The U.S. is the third largest seafood consumer in the world – commercial and recreational fisheries combined contribute $163 billion in sales impacts to total consumer spending annually and create an estimated 1.88 million jobs. The organisms likely to be impacted by ocean acidity include commercially important groups (e.g. clams, scallops, oysters, mussels, lobsters, crabs, and shrimp), which provide 50% of total fisheries revenue, and organisms that serve as primary food sources for other commercially important species all the way up the food chain to top predators like tuna. Healthy coral reefs are the foundation of many viable fisheries, as well as the source of tourism and recreation revenues, such as in the Florida Keys National Marine Sanctuary. Changes to the structural stability of coastal reefs may reduce the protection they offer to coastal communities against storm surges and hurricanes.

The West Coast shellfish industry is taking steps to become more resilient to the impacts of ocean acidification. Shellfish are an integral part of many coastal communities throughout the Pacific Northwest contributing a total of $278 million per year in economic activity to rural communities along the coast. Beginning in 2007, oyster larvae at Whiskey Creek hatchery started dying in huge numbers reducing the annual production to 25% of normal levels. Research at the hatchery identified the upwelling of acid seawater as the major contributor to these larval events. Subsequent monitoring of seawater quality has allowed Whiskey Creek to ‘pick their moments’, significantly increasing hatchery production. The success of these efforts underlies the importance of reliable, real-time data as a management tool. Collaborations like the one at Whiskey Creek between industry and research result in a new network of monitoring stations in areas of commercial importance, all to the benefit of working waterfronts.

Natural ResourcesArticle.