Organisms In 33.6 Million Year Old Ice Pack Evolved To Survive
Lawrence LeBlond for redOrbit.com – Your Universe Online
Researchers publishing a paper in the latest issue of the journal Science have found through Antarctic planktonic ice core examinations that the continental ice cap formed more than 33 million years ago.
Scientists from the Andalusian Institute of Earth Sciences (IACT), a joint collaboration between the University of Granada and the Spanish National Research Council (CSIC), said the seasonal primary productivity of planktonic communities appeared with the first ice. They added that this phenomenon, which is still ongoing today, influences the global food web.
The ice cap was formed during the Oligocene (33.6 million years ago), according to carbon dating of the research data. Prior to the Oligocene, the southern continent had a warm tropical climate, teeming with life. However, when the cold came, most life forms died. Those that were able to adapt to the climate change, survived throughout time to the present age.
The paleoclimatic information was obtained through the work of the Integrated Ocean Drilling Program expedition, which bore down into the sediment strata of the Antarctic depths to the preserved fossils. Carlota Escutia, lead researcher from the IACT, said the “fossil record of dinoflagellate cyst communities reflects the substantial reduction and specialization of these species that took place when the ice cap became established and, with it, marked seasonal ice-pack formation and melting began.”
Dinoflagellates evolved into more simplified organisms enabling them to survive the formation of the Antarctic ice cap as well as thrive in the continual melting and freezing of the ice sheet during the seasonal changes. Over the course of millions of years, the dinoflagellates continued to evolve to assume their present form today.
As the ice-pack melts during the approaching summer, an increase in productivity of endemic plankton communities occurs. The ice melt frees the nutrients it has accumulated throughout the previous year and releases it for consumption by plankton. “This phenomenon influences the dynamics of global primary productivity,” said Dr. Escutia in a statement.
The dinoflagellate communities have continued to evolve throughout history of the ice pack. However, Escutia thinks “the great change came when the species simplified their form and found they were forced to adapt to the new climatic conditions.”