New study to investigate the impacts of ocean acidification in
the Southern Ocean
07 January 2013
To begin 2013 with a big bang, a team of
thirty scientists, from eight of the UK’s top research
laboratories, will be setting out on an oceanographic mission to
study the effect of ocean acidification in waters near Antarctica.
The five week long research cruise, aboard the Natural Environment
Research Council’s RRS James Clark Ross, departs on
8th January for some of the coldest waters on
Earth.
The ocean is an integral part of the climate system. By absorbing
large amounts of the carbon dioxide (CO2), mostly
produced as result of our use of fossil fuels, the ocean helps to
slow the rate and severity of climate change. The global ocean has
absorbed more than 30% of the total CO2 produced by
human activities in the past 200 years. While this can be seen
as a benefit, the down side is that as the ocean absorbs more and
more CO2 its chemistry changes and the seawater moves
down the pH scale towards acidity. This process is known as ocean
acidification.
Cold waters provide best
indications
Cold waters naturally hold more
CO2 than warmer waters so the icy Southern Ocean is
expected to be especially informative for studying the effects of
ocean acidification. Additionally, deep-water upwelling around
Antarctica brings water to the surface that already contains very
high levels of CO2. For these reasons, the waters of the
Southern Ocean are likely to provide a unique window into how the
marine environment will respond to higher CO2 levels in
the future. This expedition will include a visit to the Weddell
Sea, which has some of the coldest surface waters
(-1.8⁰C) anywhere in the world.
During the expedition, scientists will study
the impact of the changing chemistry on marine organisms and
ecosystems, on the cycling of carbon and nutrients in the sea and
on how the sea interacts with the atmosphere to influence
climate.
Parallel investigations
Firstly, the researchers will look at how
ecosystems vary between locations where the chemistry of seawater
is naturally more acidic and those where it is more alkaline.
This approach will provide insights on how acidification may affect
organisms living in their natural environment, where natural
selection and adaptation have had time to play out.
A second approach is experimental, using tanks
of natural seawater collected from the upper ocean and brought into
controlled conditions on deck. This natural seawater will be
subjected to various levels of carbon dioxide that are likely to
occur in the future.
Dr Geraint Tarling, a British Antarctic Survey
Researcher and the leader of this expedition says: “This
is the most comprehensive investigation into the response of the
Southern Ocean ecosystem to ocean acidification yet mounted. The
investigative team encompasses some of the most experienced marine
researchers from the UK. The team will not only look at how
different parts of the ecosystem respond in isolation, but also see
how effects interact to produce an ecosystem-level response. The
work on this expedition will build on recent evidence of ocean
acidification dissolving the shells of marine snails, known as
pteropods, in the Southern Ocean that was recently published in
Nature Geoscience (*for reference, please see left hand
column).
Professor Toby Tyrrell from the National
Oceanography Centre and coordinator of the UKOA Sea Surface
Consortium added: “Another reason
for visiting the Southern Ocean is that it is also an unusually
stable environment, with surprisingly little seasonal variation.
The sea remains extremely cold even in summer. As the local
organisms are not exposed to much natural variation, they could be
more susceptible to human-induced variations. It is important for
us to find out whether this supposition is correct.”