Survival of the Smallest |at Play in World’s Oceans

     (CN) — Smaller is better, at least when it comes to survival in the Earth’s oceans these days.
     In a study published Wednesday in the journal Science, researchers present findings that indicate smaller marine animal species have a better chance of avoiding extinction — a rare dynamic in the history of the planet.
     As subfamilies — genera — of marine species grow larger in body size, their likelihood of being classified as threatened with extinctions increases by an even greater amount.
     “The proportion of species that are threatened increases enormously as body size increases,” lead author Jonathan Payne told the Associated Press.
     Payne, a paleobiologist at Stanford University, said smaller creatures were more likely to die off in past extinctions.
     According to the study, almost none of the genera that have species averaging 0.4 inches long are threatened with extinction, while 23 percent of those that are 3.9 inches on average are threatened. Of the genera that average 39 inches, 40 percent are endangered, and 86 percent of those measuring 32.8 feet are vulnerable.
     While these species are not extinct yet, they are on the Red List of threatened and endangered species created by the International Union for the Conservation of Nature (IUCN).
     The blue whale, the largest living animal — and the largest to ever have existed at nearly 100 feet long — is on the group’s endangered list and has lost as much as 90 percent of its population in the past three generations, according to the IUCN.
     However, the bioluminescent bristlemouths, a grouping of fish that are about three inches long, have a population estimated to be in the trillions.
     Payne compared fossil records, reviewed past mass extinctions and contrasted them with current trends, concentrating on 264 genera that have the most complete ancient and modern records. Payne focused on oceans, where the fossil records are better over time.
     The mass extinction 65 million years ago that killed off the dinosaurs didn’t kill off larger marine species at higher rates than smaller ones, unlike what’s happening today.
     The study “shows us how unusual this crisis of biodiversity we have right now is,” Boris Worm, who wasn’t involved with the study, told the AP. “We have had mass extinctions before. This one is totally different than what has happened before.”
     It took Worm more than 20 years to see his first underwater right whale and basking shark, which are considered endangered and vulnerable, respectively, by the IUCN.
     “They are both in trouble and among the largest of their kind,” Worm said.
     The study didn’t attempt to explain why larger animals were more threatened, but Payne and Worm say humans are the primary suspect. Fishing and hunting, and environmental issues such as warmer and more acidic oceans stemming from greenhouse gas emissions are likely to blame.
     Payne maintains hope, pointing to northern elephant seals, which had a population below 100 in the early 1900s. There are now more than 100,000.
     But they are the exception.
     “It pains you to the core to know that these animals might be gone in a generation or two,” Worm said. “You can’t imagine a world without them. It’s such an important and beautiful part of our planet.”

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