Researchers at the ARC Centre of Excellence for Coral Reef Studies (CoECRS) recently reported in the journal Nature Climate
Change, encouraging new findings that some fish may be less vulnerable to high CO2 and an acidifying ocean than previously
feared.
study on anemone fish shows that their babies, at least, can adjust to the changes we expect to occur in the oceans by
2100, provided their parents are also raised in more acidic water.
Human activity is expected to increase the acidity of the world’s oceans by 0.3 to 0.4 pH by the end of this century, on
our present trends in CO2 emissions
How parent fish actually pass on this ability to deal with acidity to their offspring is still a mystery. The time interval
is too short for it to be genetic adaptation in the normal sense. However, it’s an important parental effect that we need
to factor in as we assess the vulnerability of the world’s fish stocks to the planet-wide changes in ocean chemistry that
humans are now causing.
Based on evidence from past major extinction events, scientists have long feared that the acidity caused by the release of
high levels of CO2 could cause havoc among sea-life, especially those which depend on calcium to form their bones and
shells. New research has also shown that higher CO2 levels can cause the nervous systems of some marine species to
malfunction.
The recent increase in ocean acidity due to human activity in releasing carbon — about 0.1 of a pH unit over the last half
century — is thought to be steeper even than in any of the past major extinctions, which eliminated between 70-90 per cent
of marine species.
What this research shows is that some species, at least, may have more capacity to cope than we thought — which could help
buy time for humanity to bring its CO2 emission under control
anemone fish are particularly hardy by nature, and may not be typical of all fish in the ocean. We need to extend these
studies to other types of fish, especially those which humans rely on for food.
Both scientists warn that the major impact on ocean acidification is likely to be on the corals themselves, and the reefs
which they form, which in turn provide the habitat for small fish such as the anemone fish. The fate of the world’s reefs
under a high human CO2 regime remains highly uncertain, they caution.
– http://www.sciencedaily.com/releases/2012/07/120703134151.htm