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Changing Ecology of Oceans: Study shows mass extinctions of larger Marine animals

In past extinctions, smaller creatures were more prone to die off but in the Earth's oceans these days, the bigger a species is, the more chances of it to go extinct

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FILE - A blue whale is shown near a cargo ship in the Santa Barbara Channel off the California coast, Aug. 14, 2008. The oceans are turning into a Darwinian topsy-turvy place, where it’s survival of the smallest and the bigger a species is, the more prone it is to die off. VOA
  • Blue whale is on the IUCN endangered list and has lost as much as 90 percent of its population in the last three generations
  • The proportion of species that are threatened increases enormously as body size increases
  • The mass extinction 65 million years ago that killed off the dinosaurs didn’t kill off bigger marine species at higher rates than smaller ones, unlike what’s happening now

Sept 16,2016: In the Earth’s oceans these days, the bigger a species is, the more prone it is to die off. That’s unheard of in the long history of mass extinctions, a new study finds.

As subfamilies of marine animal species — called genera — grow larger in body size, the likelihood of them being classified as threatened with extinction increases by an even greater amount, according to a study published Wednesday in the journal Science. In past extinctions, smaller creatures were more prone to die off, or size didn’t matter, said study lead author Jonathan Payne, a paleobiologist at Stanford University.

Almost none of the genera that have species averaging 0.4 inches (1 centimeter) long are threatened with extinction. However, 23 percent of those that are 3.9 inches (10 centimeters) are threatened, 40 percent of those that are 39 inches (1 meter) are endangered and 86 percent of those that are 32.8 feet (10 meters) are vulnerable, Payne said.

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These are species that are not extinct yet, but are on the respected Red List of threatened and endangered species created by the International Union for the Conservation of Nature.

“The proportion of species that are threatened increases enormously as body size increases,” Payne said.

Take the blue whale, not only the largest living animal, stretching close to 100 feet long, but the largest to ever have existed, Payne said. It’s on the IUCN endangered list and has lost as much as 90 percent of its population in the last three generations, according to the IUCN.

FILE – A 70-foot female blue whale, that officials believe was struck by a ship, is seen washed ashore near Fort Bragg, California, Oct. 20, 2009. As subfamilies of marine animal species grow larger in body size, the likelihood of them being classified as threatened with extinction increases by an even greater amount, according to a study published Sept. 14, 2016. VOA

On the other end of the spectrum is a grouping of fish, bioluminescent bristlemouths, that are about three inches long. They are the most abundant creatures with a backbone; the population is estimated to be in the trillions.

Focus on oceans

Payne compared fossil records, looked at past mass extinctions and compared them to current threats, concentrating on 264 genera that have the best modern and ancient records. Payne concentrated 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 bigger marine species at higher rates than smaller ones, unlike what’s happening now, Payne said.

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The study “shows us how unusual this crisis of biodiversity we have right now,” said Boris Worm, a top marine scientist at Dalhousie University in Canada. He wasn’t part of the study but praised it. “We have had mass extinctions before. This one is totally different than what has happened before.”

Worm spoke from a break during research in Canada’s Bay of Fundy, where after a more-than-20-year career he finally saw his first underwater right whale and basking shark.

“They are both in trouble and both among the largest of their kind,” Worm said.

Humans suspected

Payne’s study didn’t try to explain why larger animals were more threatened, but both he and Worm point to one main suspect: humans. Mostly through fishing and hunting, but also through environmental degradation such as warmer and more acidic oceans, humans have made it tougher for the biggest marine animals to survive, they said.

Catherine Novelli, the U.S. undersecretary of state for environment, said a world oceans conference that starts Thursday in Washington, will see the announcement of “many more” areas where nations set aside large areas of the seas where animals are protected and fishing is prohibited.

Duke University biologist Stuart Pimm also praised the study as both compelling and disturbing because “even if some species do hang on, we have massively changed the ecology of much of the oceans.”

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Payne said there is still hope, since these species haven’t gone extinct yet. He points to northern elephant seals which had a population below 100 in the early 1910s, but are now more than 100,000 strong. 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.” (VOA)

  • Manthra koliyer

    The sea animals are at a high risk of extinction due to Human intervention also.

  • Antara

    Bigger marine animals are more prone to be extincted! Tragic indeed!

  • Arya Sharan

    Human intervention in the aquatic environment has just made things worse.

Next Story

Research: Having Diverse Natural Areas Near Agriculture Helps Farmers Financially During Calamities

"New global and local policy should specifically target conserving and enhancing biodiversity"

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farmers, nature
University of British Columbia ecologist Diane Srivastava, with a damselfly, an insect often used as an indicator species for estimating biodiversity and assessing ecosystem health. (T. Zulkoskey). VOA

Farmers reap surprising benefits from having areas that are biodiverse  with many plant and animal species nearby, according to new research. A study finds that having diverse natural areas near agriculture helps farmers financially during droughts, and the more diverse the areas are, the better. Policies that preserve biodiversity near farms may ease economic pressure in places with severe droughts, the authors say.

“If you plant the same sort of crops next to a natural area that is very high in biodiversity versus one that’s very low in biodiversity, [the positive effect] spills over into the agricultural products,” said Frederik Noack, a professor of food and resource economics at the University of British Columbia who led the study.

Some of that spillover can be tied to the increased diversity of insects in places that host many different species of plants, experts say. Pollinators that help plants reproduce, like bees and moths, and spiders that prey on agricultural pests like aphids and beetles are especially important.

Noack hoped to learn if having biodiverse areas close to farms could help crops be more resistant to drought  and if that impact would be big enough to be seen in farmers’ incomes.

farmers, diversity, agriculture
Farmers reap surprising benefits from having areas that are biodiverse with many plant and animal species nearby, according to new research. Wikimedia Commons

Big data from small farms

The researchers used data from 7,556 households in 304 villages in Asia, Africa and Latin America, where farmers derive their incomes from traditional agriculture as well as forest products like lumber and firewood.

Noack and his research team looked for a connection between the level of natural biodiversity  in this case, the number of plant species in the area  and how strongly drought affected the incomes of local farmers.

The researchers had expected that greater local biodiversity would benefit farmers, and it did. Farmers in areas with half the biodiversity lost twice as much income when droughts hit during the growing season.

Noack said that initially they thought the effect was just correlated with crop diversity. “Maybe you plant more different crops in areas with higher natural biodiversity because maybe there are just more crops available in those areas and that’s actually what’s driving the effect.”

But that’s not what they found. Even when they accounted for the effect of greater crop diversity, the farmers’ incomes seemed to be stabilized just by being close to diverse natural areas that can host many types of pollinators.

farmers, agriculture, diverse
“If you plant the same sort of crops next to a natural area that is very high in biodiversity versus one that’s very low in biodiversity, [the positive effect] spills over into the agricultural products,” said Frederik Noack. Pixabay
Having access to forests was also an income stabilizer. Because forests are the result of many years of growth rather than just a single season, income from forest products is less susceptible to drought and can offset agricultural losses, the researchers found.

ALSO READ: Government to Launch Solar Scheme for Farmers to Ensure Rs. 1 Lakh Income

Encouraging conservation

Bruno Basso, an ecosystems scientist at Michigan State University who was not involved in the research, commented in an email that the researchers had been able to show that “biodiversity and forest conservation play a critical role in adapting and mitigating the negative effects of increased climate variability.” Noack hopes that this study can become part of the larger debate about conservation of natural areas.

“Should we just have protected area far away in areas that we don’t use or shall we try to integrate that into normal land use?” said Noack. “This study actually says maybe we should at least have some level of biodiversity conservation in the agricultural landscape because of this positive spillover.” Basso agreed. “New global and local policy should specifically target conserving and enhancing biodiversity,” he said. (VOA)