Date and Time
Bath Royal Literary and Scientific Institution, 16-18 Queen Square, Bath BA1 2HN
Ammonites went extinct at the time of the end-Cretaceous asteroid impact, as did more than 90% of species of calcium carbonate-shelled plankton (coccolithophores and foraminifera).Comparable groups not possessing calcium carbonate shells were less severely affected, raising the possibility that ocean acidification, as a side effect of the collision, might have been responsible for the apparent selectivity of the extinctions (calcium carbonate dissolves in even slightly acidic seawater).
We investigated whether ocean acidification could have caused the disappearance of the calcifying organisms. I will describe the results of some modelling work we carried out. We simulated various scenarios for how the impact could have produced more acidic seawater (different possible mechanisms from impact to acidity). The results suggest that, although acidification was quite extreme in some scenarios, nevertheless it was probably not the primary reason why so many calcifiers went extinct.
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