Dec 21, 2018 - Energy & Environment

Deep ocean evolution study warns against dangers of global warming

Artist depiction of what marine life looked like during the Ediacaran period. Credit: Peter Trusler

After about 3 billion years of Earth being dominated by microbes, complex, soft-bodied organisms (up to 3 feet long) emerged in the deep oceans.

Combining evidence from the fossil record with insights from animal physiology, scientists have now put forward a new explanation for why this occurred about 570 million years ago, during a period known as the Ediacaran.

What they did: The researchers studied a species of sea anemones that are similar in their breathing methods to creatures that live in the dark, oxygen-poor deep sea environment where complex organisms also emerged.

  • By measuring how the sea anemone can cope with low levels of oxygen at different temperatures, the researchers from Stanford and Yale universities found the anemones have biological similarities to the deep sea organisms that emerged during the Ediacaran period.
  • They report that both oxygen and temperature are important regulators of where organisms can flourish, and that the thermal optimum for anemones is relatively fickle.
  • The lack of temperature fluctuations in the deep ocean may help explain why complex life first emerged there during the Ediacaran, the study finds.

The big picture: The study suggests aquatic organisms may be quite vulnerable to acidifying and warming waters today, due to global climate change and other factors.

  • Authors Tom Boag and Erik Sperling of Stanford told Axios the study's results make them more concerned about the oceans' fate in a warming world.
"It’s very clear from the fossil record that oxygen is one of the main levers driving animal life in the ocean or the distribution of animals in the ocean, and so as we change oxygen levels in the modern and future ocean, we’re going to expect big changes to where organisms are going to be able to live.”
— Erik Sperling, study co-author
  • Boag specifically warned that warming oceans with lowering amounts of oxygen, like we have today, have been associated with high levels of extinction in the past.

Yes, but: This study puts forward a hypothesis about deep ocean evolution — namely the crucial roles played by oxygen and temperature fluctuations — that needs to be reproduced by additional research before its findings are accepted by the broader scientific community. New fossil evidence or data from physiological studies could go against their hypothesis, for example.

Go deeper