PALO ALTO, Calif., Sept. 14 (UPI) -- A new survey of extinction patterns suggests the ocean's largest species are most likely to be wiped out by humans.
"We've found that extinction threat in the modern oceans is very strongly associated with larger body size," Jonathan Payne, a paleobiologist at Stanford University, said in a news release. "This is most likely due to people targeting larger species for consumption first."
Payne and his colleagues look at the relationship between risk of extinction and body size among mollusks and vertebrates over the last 500 years. The researchers then compared modern extinction patterns to prehistoric extinction patterns. Their analysis looked at the fossil record stretching back 445 million years, but focused most intently on the last 66 million years.
Their findings were detailed in a new paper, published this week in the journal Science.
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"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," said Noel Heim, a postdoctoral researcher in Payne's lab and co-author of the new study.
Specifically, larger species in the modern ocean are more likely to become extinct. Scientists calculated that over the last 500 years, a 10-fold increase in body mass corresponds with a 13-fold increase in the threat of extinction.
Previous studies have highlighted the role the ocean's largest creatures play in recycling nutrients throughout marine ecosystems. Therefore, scientists hypothesize that the disappearance of the ocean's largest species is especially damaging and disruptive to marine food chains.
The worrisome pattern recalls the disappearance of megafauna -- mammoths and saber-toothed tigers -- from the planet's continents at the end of the last ice age.
"We see this over and over again," Heim said. "Humans enter into a new ecosystem, and the largest animals are killed off first. Marine systems have been spared up to now, because until relatively recently, humans were restricted to coastal areas and didn't have the technology to fish in the deep ocean on an industrial scale."
Researchers hope their findings instill urgency in the efforts to better protect and manage the ocean's largest species.
