Acidification may push over-stressed oceans into the
red
8th December 2010
Rising C02 concentrations could have increasing
impacts on key fisheries and the billions depending upon them.
The future impact of rising emissions on the health of seas and
oceans may be far more wide-ranging and complex than was previously
supposed a new report released at the UN climate convention meeting
in Mexico says.
The study has brought together some of the latest scientific
research on ‘ocean acidification’ - a process triggered by
increasing concentrations of dissolved CO2 which is
changing the sea’s chemistry by lowering the pH of the marine
environment.
The study confirms concerns that some organisms, such as corals
and shellfish may find it increasingly difficult to form their
skeletons in the decades to come making it harder to survive let
alone thrive. It also shows that ocean acidification can react
together with ocean warming so that animals such as crabs have a
reduced range of temperatures they can thrive in.
This in turn may have significant future impacts on catches of
crabs, mussels and other shellfish; species dependent on coral
reefs and ones such as salmon that feed on smaller, shell-building
organisms lower down the food chain known as pteropods, for
example.
Other new research is spotlighting fresh areas of concern
including findings that some species - including the clown
fish made famous in the Disney cartoon Finding Nemo - may
find it harder to avoid their predators and to find their way
home.
If other fish react the same this again may have implications
for the marine food chain upon which billions of people depend
directly or indirectly for protein and livelihoods.
Achim Steiner, UN Under-Secretary General and Executive Director
of the UN Environment Programme (UNEP), said: “Ocean acidification
is yet another red flag being raised carrying planetary health
warnings about the uncontrolled growth in greenhouse gas emissions.
It is a new and emerging piece in the scientific jigsaw puzzle, but
one that is triggering rising concern”.
‘Whether ocean acidification—on its own-- proves to be a major
or a minor challenge to the marine environment and its food chain
is to date unknown. But the phenomenon comes against a backdrop of
already stressed seas and oceans as a result of over-fishing to
other forms of environmental degradation. Thus the public might
quite rightly ask how many red flags do governments need to see
before the message to act gets through,” he said.
The
UNEP Emerging Issues report: Environmental Consequences of
Ocean Acidification: A Threat to Food Security, has been
compiled in collaboration with the Plymouth Marine Laboratory in
the United Kingdom and scientists from other organisations
including the Intergovernmental Oceanographic Commission of
UNESCO.
Carol Turley, a senior scientist at the laboratory; Knowledge
Exchange Coordinator for the UK Ocean Acidification Research
Programme and lead author of the new report, said:”As scientists
around the world start to investigate the potential impacts of
ocean acidification we are seeing an overall negative impact from
ocean acidification directly on organisms and on some key
ecosystems that help provide food for billions. We need to start
thinking about the risk to food security”.
Dr Turley stressed that researchers were working on the
frontiers of science in respect to ocean acidification and its
potentially complex impacts on the marine environment and its
organisms.
She said some research indicated that adult lobsters for example
might actually increase shell-building in response to falling pH
levels whereas it may be the juveniles who are less able to build
healthy skeletons.
A similar possibility may arise in respect to adult and juvenile
forms of fish with the olfactory or smelling systems of some
species of young fish impaired but adults unaffected.
Meanwhile there is some evidence of other curious changes if
emissions continue to rise and concentrations of CO2
continue to build-up in the seas and oceans. For example, brittle
stars, an important part of the marine food chain, may increase
shell-building at the cost of muscle formation, some science
suggests.
“It is clearly not enough to look at a species—scientists will
need to study all parts of the life-cycle to see whether certain
forms are more or less vulnerable. Meanwhile the ability—or
inability—to build calcium-based skeletons may not be the only
impacts of acidification on the health and viability of an
organism: brittle stars perhaps being a case in point,” said Dr
Turley.
The report points out that there may be “winners” as well as
“losers” with photosynthetic organisms such as sea grasses likely
to benefit from rising acidification, yet studies of natural
CO2 vents in the Mediterranean Sea show that although
there are some “winners” the ecosystem is likely to be altered in
other ways.
It calls on governments; policy-makers and others to
consider a range of actions including:
- Rapid and substantial cuts to man-made CO2
emissions to the atmosphere in order to reduce ocean
acidification
- Determine the vulnerability to ocean
acidification of human communities dependent on marine
resources
- Identify species that are more flexible to
change and assess how these may affect ecosystems and food
security.
- Reduce other pressures on food fish stocks
to provide the best chances of success through. for example, marine
spatial planning or re-evaluating available resources and their
usage
- Assess the options for development of
environmentally sustainable ‘aquaculture’ options using species
that may be more resistant to lowered pH
- Embrace the science of ocean acidification
into fisheries management tools
Notes to Editors
Key Findings from the
Report
- Around 25% of the world’s CO2
emissions are being absorbed into the seas and oceans where it
converts to carbonic acid.
- This is lowering the pH of the oceans and
affecting its chemistry. For example the concentrations of
carbonate ions is decreasing and is linked to the ability of many
marine organisms to build reefs and shells.
- The report says the chemistry of the
oceans is being altered at a speed not seen for 65 million
years—since the extinction of the dinosaurs
- The mean pH of the marine world has
decreased by 30% and the concentration of carbonate ions has fallen
by 16% since the industrial revolution
- Based on current rates of CO2
emissions, projections show that by the end of the 21st century,
global ocean pH will decrease by a further 0.3 units, which
represents a total increase in acidity of 150%
- Fish including shellfish contribute 15% of
animal protein for three billion people world-wide, and a further
one billion people rely on fisheries for their primary source of
protein.
- The report says that many marine organisms
have ways of compensating for changes in seawater chemistry,
although they may have to spend more energy doing this in an
increasingly more acidic ocean
- However studies of mussels and sea urchin
species have shown they have only a partial or no compensation
mechanism, potentially making them more vulnerable
- Around 80% of fish catches occur in just
10% of the oceans including key areas such as Continental shelves
and estuaries.
- The report says “many of these areas are
also projected to be very vulnerable to ocean acidification this
century”
- The aquaculture industry is the fastest
growing food producer worldwide, increasing at a rate of 7% per
annum and the proportion of fish produced by aquaculture and
consumed by humans worldwide has risen to 50% of total
production
- The reports says these industries
are now at risk from future ocean acidification both directly
through the impact on the organisms themselves and indirectly
through the food webs and habitats they depend on
- Tropical reefs provide shelter and food
for an estimated 25% of known marine fish species, and account for
between 9-12% of world fish landings.
- Consequently, these coral reefs provide
food and livelihood security for some 500 million people
worldwide.
- The report says it is anticipated that
future ocean acidification is likely to affect adult and juvenile
coral growth and recruitment, coralline red algae growth, reef
structural integrity and potentially even the density of
bio-eroding grazers and predators
-
UNEP Emerging Issues: Environmental
Consequences of Ocean Acidification—A Threat to Food
Securityis available from
the
UNEP website
- The report is being launched at the 16th
Conference of the Parties to the UN Framework Convention on Climate
Change taking place in Cancun, Mexico from 29 November to 10
December 2010 http://unfccc.int/2860.php
For more information please contact Nick
Nuttall, UNEP Spokesperson/Head of Media, Mobile: +254 733 632 755
or when travelling +41 795 965 737, E-mail: Nick.Nuttall@unep.org