Bigger marine animals at greater risk of extinction

Larger-bodied marine animals are more likely to become extinct than smaller creatures, and humans are to be largely blamed for this, say researchers.

It is a pattern that is unprecedented in the history of life on Earth, and one that is likely driven by human fishing, said the study published in the journal Science.

"We've found that extinction threat in the modern oceans is very strongly associated with larger body size," said Jonathan Payne, a paleobiologist at Stanford University's School of Earth, Energy & Environmental Sciences.

"This is most likely due to people targeting larger species for consumption first," Payne noted.

For the study, the researchers put modern extinction in context by comparing them with Earth's five previous mass extinctions.

"We used the fossil record to show, in a concrete, convincing way, that what is happening in the modern oceans is really different from what has happened in the past," study co-author Noel Heim, a postdoctoral researcher in Payne's lab, said.

Specifically, the authors found that the modern era is unique in the extent to which creatures with larger body sizes are being preferentially targeted for extinction.

"What our analysis shows is that for every factor of 10 increase in body mass, the odds of being threatened by extinction go up by a factor of 13 or so," Payne said.

"The bigger you are, the more likely you are to be facing extinction," Payne noted.

The selective extinction of large-bodied animals could have serious consequences for the health of marine ecosystems, the scientists say, because they tend to be at the tops of food webs and their movements through the water column and the seafloor help cycle nutrients through the oceans, the scientists said.

--IANS

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