Stimulus details: ocean acidification

impact chain for tropical coastal areas / acidification (click nodes to view details):
Ocean acidification primarily affects coral reefs and marine organisms, with subsequent effects on people and other ecosystems. It leads to changes in the marine carbonate chemistry, which can directly cause declines in coral reef calcification and growth.[1] Erosional processes might then overcome coral growth, weakening reef stability and coral competitiveness for space and light. As a result, fleshy and non-calcifying algae will dominate, damaging biodiversity and weakening the ability of reefs to recover from disturbances.[2]

Any reef degradation and coral mortality will lead to losses in provisioning and protective (or regulating) ecosystem services.[3] Coral reefs serve as breakwaters, protecting shorelines and creating quiet habitats for other ecosystems, such as mangroves and seagrass beds. They are also an important habitat for reef fish. The loss of these ecosystem services will increase the overall vulnerability of people living in coastal areas.

Acidification is projected to have a direct impact on fish communities also. Increased CO2 dissolution in ocean waters has long-term effects on the metabolic functions, growth, and reproduction of fish, with subsequent alterations in population and species levels.[2] Seagrass beds, by contrast, are expected to benefit from the increased levels of CO2 for their photosynthesis.

To slow down acidification and minimise its impacts, mitigation measures are needed to limit anthropogenic CO2 emissions. Developing adaptation measures to minimise or delay the impacts will require additional research, such as biogeographical surveys of the range shifts of economically and ecologically critical species to adjust harvesting practices for resilience.[2] Either way, minimising human pressures constitutes a 'no-regrets' measure for increased resilience.[2]


[1]    Shaw, E. C., McNeil, B. I., Tilbrook, B., 2012. Impacts of ocean acidification in naturally variable coral reef flat ecosystems. Journal of Geophysical Research: Oceans (1978 - 2012) 117.

[2]    Guinotte, J. M., Fabry, V. J., 2008. Ocean acidification and its potential effects on marine ecosystems. Annals of the New York Academy of Sciences 1134, 320-342.

[3]    Kleypas, J. A., Yates, K. K., 2009. Coral reefs and ocean acidification. Oceanography 22, 108-117.
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