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Climate change takes a toll on critical marine species - 07/06/2016

Research by GNS Science and Victoria University of Wellington has revealed that algae critical to the marine ecosystem are sensitive to climate change.

James Crampton. Image by Margaret Low GNS Science.

James Crampton. Image by Margaret Low GNS Science. See more images in our image library.

The findings suggest that single-celled marine algae - Antarctic diatoms - are more prone to extinction during major climatic changes and large-scale cooling on Earth.

Marine algae form the base of the marine food web, are a crucial element of the cycle of carbon dioxide, and account for about 50 percent of the total biological productivity on Earth.

GNS Science and Victoria University paleontologist Professor James Crampton says the large-scale cooling stemmed from carbon dioxide fluctuations and changes in Earth’s orbit and tilt.

“Climate does naturally vary a lot and there are swings in temperature over time, and phytoplankton communities can tolerate this general variability. But we found that past a certain threshold of environmental change diatoms are vulnerable, some species become extinct and others have to evolve.”

The researchers studied diatom fossil records from ocean sediments around Antarctica that date back 15 million years.

“Over that period diatoms in the Southern Ocean have experienced five major pulses of extinction that are linked with particularly big and sharp temperature swings from warm to cold,” Professor Crampton says.

“By using new analyses of large fossil data sets, we’ve been able figure out accurate times of origination and extinction of the species, and resolve what happened in a much finer timescale than was possible previously.

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Diatoms are an interesting group to focus on because of their ecological importance - everything in the marine ecosystem relies on them.

Dr James Crampton

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“Our study shows that diatoms were affected by relatively rapid cooling in the past and appear to be sensitive to major changes in the climate system and we suspect that a similar response may occur during intervals of relatively rapid warming.”

The research was recently published in Proceedings of the National Academy of Sciences of the United States of America. Professor Crampton worked in collaboration with Dr Richard Levy from GNS Science, Victoria’s Dr Robert McKay, Professor Tim Naish and Rosie Cody, and Professor David Harwood from the University of Nebraska-Lincoln.

“Diatoms are an interesting group to focus on because of their ecological importance - everything in the marine ecosystem relies on them.

“In the future we plan to look at the flow-on effects further up the marine ecosystem and food web, and if other species that depend on the diatoms to survive become vulnerable as well.”