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How do shellfish make their shells?

The supply of shellfish we buy at the supermarket faces an uncertain future as our oceans become warmer and more acidic because of a changing climate.

A team of international scientists has launched an ambitious mission to understand how these changes in our oceans will affect several species vital to the European fishing economy and to marine biodiversity.

Currently scientists do not fully understand how shellfish, such as oysters, mussels, scallops and clams produce their shells, or how a change in environment will affect their populations.  To address this, the European Union is funding a €3.6 million programme called CACHE (Calcium in a Changing Environment).

Coordinated by the British Antarctic Survey (BAS) in Cambridge this multi-national programme, which aims to train a new generation of marine scientists, will look at every aspect of how the animals produce their shells and strive to identify populations that are resilient to climate change.

The shellfish industry is an important contributor to the European marine economy - the so-called “Blue economy” – which is currently worth €500 billion every year and provides an estimated 5.4 million jobs.

These relatively small animals play an important role in the oceans because they are a crucial part of marine biodiversity and, as they make their shells out of calcium carbonate, they have a role in absorbing the greenhouse gas CO2. While the fishery industry built around them provides jobs in rural communities the animals themselves are also seen as an important and healthy food.

Shellfish have been highlighted as being particularly at risk under future climate change scenarios.

The risk comes because their shells are made of calcium carbonate – a substance which dissolves under acidic conditions. As the oceans become warmer and more acidic their shells will either thin, or the animals will have to expend more energy on producing thicker shells. This will affect their population sizes and the quality of the meat they produce, directly affecting the fisheries economy and damaging consumer choice.

The way in which these creatures produce their shells is also of interest to the biotech industry which is interested in mimicking (in a process known as biomimicry) the way in which shellfish take a soluble compound like calcium to make solid, robust structures. Better understanding could also reduce the carbon footprint of producing construction materials and create the potential for “fixing” CO2 into the building process.

The species being looked at are the king scallop (Pecten maximus), the Pacific oyster, (Crassostrea gigas), the blue mussel (Mytilus edulis) and the soft shell clam (Mya arenaria).  The group will also study the native oyster (Ostrea edulis) to help conservation plans as it is listed as a “priority species” in the UK.

Dr Melody Clark of BAS, who is the programme coordinator, said: “We know very little about how marine animals regulate calcium to produce a shell and how these processes might be affected when the environmental conditions change.  This is the major science challenge which our young scientists are going to tackle over the next four years.”

At SAMS, Dr Kim Last is leading the research into determining how these shellfish adapt to local environments, like Scottish sea lochs. Sea lochs provide habitats with varying degrees of naturally acidified and diluted seawater.

Working alongside Dr Tom Wilding, Dr Last explained how Scottish sea lochs provide an ideal natural experimental system to better understand the physiological and genetic mechanisms of calcification.

"We'll be trying to find out, for example, whether there is genetic resilience to increased acidity and salinity within species or are populations simply adapted to specific loch conditions?

"This research will not only allow us to better understand calcification mechanisms in wild and cultured animals but will also inform the shellfish industry on the resilience and adaptability of bivalves to climate change, hence ultimately influencing the profitability of this sector,” said Dr Last.

CACHE is a €3.6 million Marie Curie Initial Training Network (ITN). It brings together 10 partners (including SAMS, the British Antarctic Survey and the universities of Cambridge and Edinburgh) from six European countries and includes three SMEs and a shellfish consultancy.  It started in 2013 and will run for 4 years.  It will train 10 young researchers to PhD level and enhance the training and careers of 4 early-stage post-doctoral researchers.

For more information on the programme and full details of the recruitment process, please visit the CACHE website.  Recruitment is now open. Closing date January 12, 2014.


For more information on Dr Kim Last's work, please click here

For information on a CACHE PhD at SAMS, please click here


British Antarctic Survey

For more information on this press release, please contact Paul B Holland, communications manager, at the British Antarctic Survey in Cambridge by email or on  +44 (0)1223 221226, +44 (0)7740 822229.

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