From: Allison Winter, ENN
Published May 23, 2013 04:17 PM

Ocean Acidification and Deep-sea Organisms

Although the natural absorption of CO2 by the world's oceans help mitigate climate effects, the resulting decrease in pH causes ocean acidification which can have negative consequences for much of the marine life, specifically calcifiers such as corals and mollusks that construct their shells and skeletons from calcium carbonate.

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To study the effects of ocean acidification on deep-sea organisms, a team of researchers at the University of Bristol and Yale University used Synchrotron Radiation X-ray Tomographic Microscopy (SRXTM) of the TOMCAT beamline at the Paul Scherer Institute in Switzerland. This technology is capable of generating high resolution, 3D images of deep-sea benthic foraminifera, unicellular organisms that make microscopic fossil shells.

About 55.5 million years ago, the earth underwent a global warming of five degrees Celsius, which caused severe ocean acidification, and widespread extinction of microscopic organisms living on the deep-sea floor (foraminifera). By studying the survivors of this extinction, unique insight was discovered from past warming events that may resemble future consequences of fossil fuel CO2 emissions.

Research shows that the calcifying organisms actually increased the thickness of their shells during ocean acidification. Also organisms living buried within the sediment were able to survive better than forms living on the sediment surface.

Dr Laura Foster, first author of the paper, and post-doctoral researcher at the University of Bristol's School of Earth Sciences, explained: "We use state-of-the-art techniques to virtually section foraminifera, and gain insight in their shell construction, duration of life and mode of reproduction. We have much to learn about and from single-celled organisms, which serve as monitoring organisms for deep-sea calcifiers in general, and their response to past ocean acidification. They are a crucial part of the huge deep-sea oceanic ecosystem, and understanding what happened to them during acidification in the past is critical to improving projections on the effects of future climate change."

Dr Daniela Schmidt, a Royal Society Research Fellow at Bristol's School of Earth Sciences, added: "Short-term experiments cannot provide information on ways in which organisms can acclimatise, adapt or evolve in the long term. We used the geological record to examine the impact of multiple stressors, such as changes in carbonate chemistry and temperature, to provide information on how organisms adapt to large CO2 releases."

The research, by scientists from the University of Bristol (UK) and Yale University (USA), is reported in this week's early edition of the Proceedings of the National Academies of Science.

Read more at the University of Bristol.

Coral image via Shutterstock.

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