2.12 Ocean Acidification

Ocean Acidification (often referred to as OA) refers to an increase in the acidity of the ocean over an extended period, typically decades or longer, which is caused primarily by uptake of carbon dioxide from the atmosphere (IPCC 2007). It is a great concern as left unchecked and working in concert with the effects of global warming, OA will profoundly affect marine ecosystems and species (Hoegh-Guildberg & Bruno 2010; Veron 2010). For example the world’s coral reef ecosystems will be functionally non-viable once the full effect of current atmospheric CO2 levels take effect (Coral Crisis Working Group position statement 2009; Veron et al 2009, WAZA Position Statement 2010 and Veron 2012).

OA is a great threat to the polar region marine food chains and is already pronounced in these cold region oceans, due to the higher capacity of cold waters to absorb carbon dioxide. The Arctic Monitoring and Assessment Programme’s Arctic Ocean Acidification Assessment report states that indirect OA effects include changes in food supply or other resources. For example, birds and mammals are not likely to be directly affected by acidification but may be indirectly affected if their food sources decline, expand, relocate, or otherwise change in response to ocean acidification. OA may alter the extent to which nutrients and essential trace elements in seawater are available to marine organisms. Some shell-building Arctic molluscs are likely to be negatively affected by OA, especially at early life stages. Juvenile and adult fishes are thought likely to cope with the acidification levels projected for the next century, but fish eggs and early larval stages may be more sensitive. In general, early life stages are more susceptible to direct effects of OA than later life stages (AMAP 2013). Critically important food web species such as pteropods and other calcium carbonate shell building animals are examples of directly vulnerable polar region species, the loss of which reduce the availability of nutrients and the ability of oceans to absorb atmospheric CO2. (IPCC 2007) (Sommerkorn M. 2008).

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