Microscopic ocean algae called coccolithophores are providing clues about the impact of climate change both now and many millions of years ago. The study found that their response to environmental change varies between species, in terms of how quickly they grow.
Coccolithophores, a type of plankton, are not only widespread in the modern ocean but they are also prolific in the fossil record because their tiny calcium carbonate shells are preserved on the seafloor after death the vast chalk cliffs of Dover, for example, are almost entirely made of fossilised coccolithophores.
The fate of coccolithophores under changing environmental conditions is of interest because of their important role in the marine ecosystem and carbon cycle. Because of their calcite shells, these organisms are potentially sensitive to ocean acidification, which occurs when rising atmospheric carbon dioxide (CO2) is absorbed by the ocean, increasing its acidity.
There are many different species of coccolithophore and in an article, published in Nature Geoscience this week, the scientists report that they responded in different ways to a rapid climate warming event that occurred 56 million years ago, the Palaeocene-Eocene Thermal Maximum (PETM).
The study, involving researchers from the University of Southampton, the National Oceanography Centre and University College London, found that the species Toweius pertusus continued to reproduce relatively quickly despite rapidly changing environmental conditions. This would have provided a competitive advantage and is perhaps why closely-related modern-day species considered to be its descendants, (such as Emiliana huxleyi) still thrive today.
In contrast, the species Coccolithus pelagicus grew more slowly during the period of greatest warmth and this inability to maintain high growth rates may explain why its descendants are less abundant and less widespread in the modern o
|Contact: Catherine Beswick|
National Oceanography Centre, Southampton (UK)