The marine environment is home to a vast and diverse range of organisms and ecosystems, all of which will directly or indirectly experience, to a greater or lesser degree, changes in ocean chemistry associated with ocean acidification. For many marine organisms, marine carbonate chemistry and pH are known to play important roles in key physiological processes (e.g. calcification in corals and shellfish, acid/base balance, fertilisation etc) that ultimately influence their behaviour, growth, development and/or survival. Some research suggests that ocean acidification has already begun to have detectable impacts on some biological processes.
Most conclusions about biological responses to ocean acidification in Australian waters come from laboratory manipulations rather than in situ observations. However there is observational data documenting already-underway changes in calcification in Southern Ocean zooplankton and in Great Barrier Reef corals. Though unambiguous attribution of these observed trends to acidification is still uncertain, they suggest acidification may have already begun to have detectable impacts on biological processes.
Similarly, a range of physiological processes are sensitive to pH itself. Changing pH also influences other important aspects of seawater chemistry, such as the availability of nitrogen and iron (both necessary for marine plant production).
Given that a significant proportion of the global (including Australian) human population is directly or indirectly reliant on the ecosystem services provided by the ocean (e.g. for food security, employment, tourism), many governments are becoming increasingly concerned with understanding the likely ecological, economic and social implications of ocean acidification