First research cruise to study ocean acidification in European
1st September 2011
In the summer of 2011, the first research cruise specifically
designed to study ocean acidification in European waters was
conducted, with 24 scientists from eight different UK institutes
aboard the RRS Discovery. During this 35 day cruise, 21 of those
scientists focused their research on the impact of ocean
acidification on the pelagic zone (seawater that is not close to
the bottom or near to the shore), looking at the impact of the
changing chemistry on marine organisms and ecosystems in the water
column, the cycling of carbon and nutrients in the sea and how the
sea interacts with the atmosphere to influence climate.
Three of the scientists had their attention focused on some
out-of-sight animals which may also be threatened by changing ocean
chemistry – the enigmatic cold-water coral species Lophelia
pertusa. To many in the UK, the thought of coral reefs in UK
waters is surprising, with images of tropical corals in their
bright colours springing to mind. But, off the Hebridean island of
Mingulay extensive reefs are formed from cold-water corals, which
support a variety of fish life and invertebrate species.
Laura Wicks, Sebastian Hennige and Murray Roberts from
Heriot-Watt University, Edinburgh, are part of the UK Ocean
Acidification Benthic Research Consortium. Aboard RRS Discovery
they carefully sampled the corals from the Mingulay Reef Complex to
use in a series of experiments on board.
Currently, little is known about how these animals function, for
example their food preferences, and how they cope with changes in
the water temperature in which they live. As such the cruise
represented a unique opportunity for the scientists to study how
freshly-sampled corals responded to changes in their diet,
temperature, and perhaps most importantly the changing chemistry of
the water in which they live.
Increasing acidity in the oceans linked to
increased carbon dioxide in the atmosphere could seriously damage
marine creatures, like cold-water corals, which need calcium
carbonate (CaCO3) to build their skeletons. Once
absorbed in seawater, carbon dioxide forms carbonic acid and lowers
ocean pH, which makes carbonate less available and thus makes it
harder for corals to build their skeletons. Understanding how
corals respond to the future chemistry of the oceans, and whether
they can still grow, feed and reproduce are important knowledge
gaps which these scientists are addressing.
Laura and Sebastian subjected the corals they collected to
a range of environmental conditions, including increased
temperatures and enhanced CO2 levels and measured their
metabolic and growth response. Now they are back on dry land, the
sample processing from those experiments begins, with results
expected in the next few months.Additionally, corals were collected
to take part in a long-term experiment in a purpose built mesocosm
system at Heriot Watt University.
For 18 months, these corals will be subject to a range of
temperature and CO2 levels, and their growth and
metabolism monitored. This will help us to understand whether
corals have the ability to acclimate to new conditions. The
chemistry and temperature of the oceans are changing rapidly; only
by understanding how animals respond to such changes will we be
able to make predictions on the future for cold-water corals and
the communities they support.