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Biological Consequences of OA

The primary effects of OA

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    Pteropods are tiny swimming marine creatures like snails, whose shells can dissolve even when they are alive in an acidifying ocean.
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    Corals create aragonite skeletons that are damaged by ocean acidification.  Research is ongoing to determine corals' specific responses to OA.
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    More images coming soon of a wider array of affected organisms...

Some marine organisms that form hard calcium carbonate shells and skeletons will be among the first groups affected by OA.  These organisms use a form of calcium carbonate (CaCO3) called aragonite, which is one of the more easily dissolved types of CaCO3. As OA progresses, areas hospitable to aragonite will shrink and these organisms may be harmed as making or maintaining their shells becomes more difficult. (add link to chemistry section) (See slide show at right)

In addition to harming some shelled organisms, OA may also directly harm non-shelled organisms.  The changes in ocean chemistry associated with decreasing pH and increasing CO2 may also affect photosynthesis in marine plants and phytoplankton, and it may alter respiration and reproduction in all types of organisms. If respiration and reproduction become more difficult for many organisms, marine populations may decrease.

Researchers are now studying the potential effects of OA on marine life. In addition to affecting creatures with shells, OA is expected to indirectly affect all marine life.  For example,
  • Losing shelled creatures may make predators go hungry, changing marine food webs
  • Losing coral may decrease ocean habitats, increase coastal damage from storms, and mangrove damage
  • Thinning shells may change the way CO2 moves through the ocean (see the video "Should we Manipulate the Ocean?" for an explanation)

Researchers have found that some of OA's effects on ocean life are surprising, and their long-term consequences are hard to predict.
  • More acidic oceans will transmit sound better, creating a noisier environment and possibly confusing some animals, like whales and dolphins
  • Adult crustacean shells may become thicker, with yet-unknown ecosystem effects
  • Seagrass and macroalgae grow well, increasing herbivore numbers

Last updated: March 20, 2009

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