Researchers in the Laboratoire d'Océanographie at Villefranche (LOV)
(Centre national de la recherche scientifique (CNRS)/Université Pierre et
Marie Curie (UPMC)) have just demonstrated that key marine organisms, such
as deep-water corals and pteropods (shelled pelagic mollusks) will be
profoundly affected ocean acidification during the years to come.
Since 1800, one third of anthropogenic CO2 emissions has been
absorbed by the oceans, corresponding to an annual uptake of one ton of CO2
per person. This massive absorption has allowed to partly mitigate climate
change but it has also caused a major disruption to the chemistry of
seawater. Indeed, this absorbed CO2 causes an acidification of
the oceans and, at the current rate of emissions, it is estimated that their
pH will fall by 0.4 units between now and 2100. This corresponds to a 3-fold
increase of the mean acidity of the oceans, which is unprecedented during
the past 20 million years. The LOV team, led by Jean-Pierre Gattuso, studied
the impact of such a reduction in pH on calcifying organisms in
Kongsfjorden, Svalbard. Pteropods (pelagic marine mollusks) and deep-water
corals, both playing essential roles in their respective ecosystems, live in
areas that will be among the first to be affected by ocean acidification.
The pteropod Limacina helicina plays an important role in the food
chain and functioning of the Arctic marine ecosystem. Its calcium carbonate
shell provides vital protection. However, the LOV study has shown that the
shell of this mollusk develops at a rate that is 30% slower when it is kept
in seawater with the characteristics anticipated in the year 2100. An even
more marked reduction (50%) has been measured in the cold-water coral
Lophelia pertusa. While tropical coral reefs are built by a large number
of species, coral communities in cold waters are constructed by one or two
species but provide shelter for many others. A reduction in the growth of
reef-building corals due to ocean acidification may therefore threaten the
very existence of these biological structures.
These first results raise major concerns about the future of pteropods,
deep-water corals and the organisms that depend on them for nutrition or
habitat. Research programs such as EPOCA (European Project on OCean
Acidification), coordinated by CNRS, are planning new studies on other
marine organisms and ecosystems. They are carrying out long-term experiments
to study the combined impact of ocean acidification and other parameters
that will also be modified during the decades to come, such as temperature
and nutrient concentrations.
Ocean acidification can only be controlled by limiting future atmospheric
levels of CO2. Negotiations aimed at reducing greenhouse gas
emissions are under way and should be finalized in Copenhagen next December.
These negotiations must take account not only of increased temperature but
also of the acidic nature of CO2 which, once absorbed by the
oceans, will have potentially dramatic effects on numerous marine organisms
and ecosystems.
The EU FP7 large-scale integrating project EPOCA was launched in May 2008
with the overall goal to fill the numerous gaps in our understanding of
ocean acidification and its consequences. The EPOCA consortium brings
together more than 100 researchers from 27 institutes and 9 European
countries. The research of this four-year long project is partly funded by
the European Commission.
(Source:
www.epoca-project.eu)
References:
Comeau S., Gorsky G., Jeffree R., Teyssié J. L., Gattuso J.-P. (2009) Impact
of ocean acidification on a key Arctic pelagic mollusc (Limacina helicina).
Biogeosciences 6 (9) 1877-1882.
Maier C., Hegeman J., Weinbauer M. G., Gattuso J.-P. (2009) Calcification of
the cold-water coral Lophelia pertusa under ambient and reduced pH.
Biogeosciences 6 (8) 1671-1680.
Contact: Jean-Pierre Gattuso
Read more:
http://www.epoca-project.eu/
<< Return
|
|
The pteropod Limacina helicina (Photo: Alfred
Wegener Institute).
|
