Mass Extinction Led to Reordering of Marine Ecosystems

| Mon Nov. 27, 2006 9:12 AM EST

Scientists have recently discovered that the "Great Dying," 250 million years ago when a massive extinction wiped out nearly 95 percent of marine life and 70 percent of land species, also brought about a fundamental change in the ecology of the oceans.

Published in Friday's Science, a report from scientists with The Field Museum in Chicago have found that ecologically simple marine communities were displaced by complex communities initiating a new pattern that has continued since: the dominance of higher-metabolism, mobile organisms like snails, clams and crabs that go out and find their own food over the older groups of low-metabolism, stationery organisms that filter nutrients from the water.

The scientists were studying how life forms in the oceans changed over the last 540 million years when they stumbled on the data which shows that there had been sudden relative abundance in marine life shortly after the "great dying."

An accompanying article suggests that this striking change escaped detection until now because previous research relied on single numbers--such as the number of species alive at one particular time or the distribution of species in a local community--to track the diversity of marine life while this research used a huge repository of fossil data in the new Paleobiology Database.

This is only the beginning of what this cool sounding database will tell us about the earth and its species' early tracks. The lead author of the study, Peter J. Wagner says, "We think these are the first analyses of this type at this large scale."

"Tracing how marine communities became more complex over hundreds of millions of years is important because it shows us that there was not an inexorable trend towards modern ecosystems. If not for this one enormous extinction event at the end of the Permian, then marine ecosystems today might still be like they were 250 million years ago."

These results also might cause scientists to shift their view of how humans are affecting marine ecosystems today. Wagner added: "Studies by modern marine ecologists suggest that humans are reducing certain marine ecosystems to something reminiscent of 550 million years ago, prior to the explosion of animal diversity. The asteroid that wiped out the dinosaurs couldn't manage that."

The research is new, the whys are still unclear, but for now this discovery is opening the door to exciting areas of research that hopefully can better inform us on the history, and the mysteries, of the deep.