Unexpected Effects of Ocean Acidification on Deep-sea Organisms
About 55.5 million years ago, geologically rapid emission of a large volume of greenhouse gases at the Paleocene-Eocene boundary (PETM) led to global warming of about 5oC, severe ocean acidification, and widespread extinction of microscopic organisms living on the deep-sea floor (foraminifera). A study of survivors of the extinction provides unique insight into the response of deep-sea calcifiers to past episodes which resemble the potential future consequences of fossil fuel CO2 emissions. The organisms, contrary to expectations from experiments, actually increased the thickness of their shells during ocean acidification, with organisms living buried within the sediment able to survive better than forms living on the sediment surface. 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.