Global scholars – Australia – Ocean acidification

Ocean acidification has been called “the evil twin” of climate change. Ignored or unappreciated for decades, this phenomenon begins with the absorption of atmospheric CO2 by the oceans which results in changes in ocean chemistry, including a reduction in the pH of seawater.

The good news is that approximately one-third of CO2 emissions have been soaked up by the oceans, which has slowed global warming.

The bad new is that this CO2 triggers the formation of carbonic acid, the reduction of seawater pH, the destruction of carbonate ions required to produce the calcium carbonate skeletons of hard corals, the shells of oysters, clams, and scallops, and the coverings of critical species of oxygen-producing phytoplankton.

A high CO2 / low pH world can cause dramatic reductions in the growth of corals and certain seaweeds. Some have predicted that within this century the combination of acidification and higher sea temperatures will trigger the loss of reefs worldwide. The growth of certain shellfish species may be impacted as well. For example, the Chesapeake Bay oyster suffers reduced growth and a thinning of shells at low pH. On the west coast of the U.S. several aquaculture facilities struggle to grow shellfish where once they had been plentiful. Unfortunately, the effects of OA have been examined for only a few marine species, so it is difficult to predict how marine communities are likely to respond to acidification.

The only way to study the potential impacts of OA on marine species in situ is by using a Free-Ocean-Carbon-Enrichment (F.O.C.E.) system. Only three operational systems exist – one was designed at UQ and another was developed in Dr. Arnold’s lab here at Dickinson. F.O.C.E. systems mimic the conditions of climate change – and in particular the high CO2 /low pH conditions of ocean acidification – under otherwise natural conditions. The Dickinson F.O.C.E. system was designed as a portable, near-shore system and was tested in 2009-2011 in Florida and Maryland (USA). Student teams will use the F.O.C.E. system to further investigate the impact of OA and help address what was deemed a high priority, critical need by no fewer than five international panels on ocean acidification.

Global scholars – Australia web site. Article.

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