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Microscopic marine creatures may lose teeth as ocean acidification kicks in

19 July 2013

Top marine scientists from around the globe meet in St Andrews, Scotland, to share their knowledge on the threat posed by increasing amounts of carbon dioxide entering the sea.

Amongst many other findings on how rising CO2 levels in the atmosphere may affect life in the ocean, UK marine scientists have made the startling observation that microscopic organisms, called foraminifera, suffer the equivalent of tooth-decay as seawater moves along the scale towards acidity. Foraminifera are tiny single-celled organisms that build intricate shells to protect themselves. They can feed on algal cells called diatoms, which they break open using tooth-like structures on their shells. Experiments carried out at the University of St Andrews show that as seawater increases in acidity (reduced pH), these ‘teeth’ are reduced in number and size, with many becoming deformed, likely to make them much less effective at feeding. Since ‘forams’ may number 500,000 in a square metre of marine sediment, other organisms further up the food web are also likely to be affected by these changes.

Carbon dioxide (CO2) is a natural component of our atmosphere, essential for the growth of plants, terrestrial and aquatic, which sustain life on Earth. But too much CO2 is also a threat, being the major greenhouse gas responsible for climate change. Less well known is the role of CO2 in increasing ocean acidity, by forming carbonic acid: this lowers pH and causes other chemical changes to seawater. Marine scientists are seriously concerned that these changes will have a significant impact on marine life (and ourselves), with consequences for shellfish, cold- and warm-water corals, as well as many other components of ocean food webs.

The UK government is at the forefront of asking how important these effects might be, through its co-funding, via the Department for Food and Rural Affairs (Defra) and the Department for Energy and Climate Change (DECC), of the UK Ocean Acidification research programme (UKOA), led by the Natural Environment Research Council (NERC). Crucial issues include how ocean acidification will interact with warming and other stressors; whether some life stages of marine organisms (e.g. their eggs, larvae and juveniles) are more sensitive than others; and whether ocean acidification impacts have occurred previously in Earth’s history. 

”The studies on foraminifera are only a small part of the story of ocean acidification impacts” said Professor David Paterson of the University of St Andrews. “But we know that many species were lost from the fossil record the last time that CO2 rapidly rose, around 55 million years ago, with other major disruptions to marine life. The threat of future ocean acidification is very real, and comes at a time when the human population depends more than ever on a healthy and productive marine environment”.

The latest research results on these topics will be discussed at the UKOA annual meeting, held 22-24 July at the University of St Andrews. This meeting is directly followed by the 2nd International Workshop on the Global Ocean Acidification Observing Network (GOA-ON); an international gathering of around 80 ocean acidification scientists, from 25 countries, who are developing a global plan to improve the measurement of ocean acidification and its ecological effects. A live webcast of the joint UKOA / GOA-ON session will be available on the afternoon Wednesday 24th July. Please follow this link for further details and full speaker programme.

In addition to attracting very strong interest from research scientists, the Global Ocean Acidification Observing Network (GOA-ON) involves UN agencies and other influential bodies determining marine policy. The opening session of the GOA-ON workshop on 24 July will be addressed by Dr Wendy Watson-Wright, the Executive Secretary of the Intergovernmental Oceanographic Commission (IOC of UNESCO) and Dr Darius Campbell, the Executive Secretary of the OSPAR Convention for the protection of the marine environment of the North East Atlantic. The GOA-ON workshop has been jointly planned by NERC, through its UKOA programme, the US National Oceanographic and Atmospheric Administration (NOAA) and representatives of other international organisations.

“There have already been enough measurements around the world to conclusively demonstrate that ocean acidification is occurring” commented Dr Phil Williamson, the NERC co-chair of the GOA-ON workshop, and Science Coordinator of the UKOA programme. “But there are regional differences that we can’t fully explain. We now need joined-up science to observe not only chemical changes but also ecological responses, to improve threat assessments and provide the evidence for national and international policy action”.