Humans account for little next to plants, … worms

Mass extinction looms

WASHINGTON, May 22, (Agencies): When you weigh all life on Earth, billions of humans don’t amount to much compared to trees, earthworms or even viruses. But we really know how to throw what little weight we have around, according to a first-of-its-kind global census of the footprint of life on the planet.

Humans only add up to about one ten-thousandth of the life on Earth, measured by the dry weight of the carbon that makes up the structure of all living things, also known as biomass.

The planet’s real heavyweights are plants. They outweigh people by about 7,500 to 1, and make up more than 80 percent of the world’s biomass, a study in Monday’s Proceedings of the National Academy of Sciences said.

Bacteria are nearly 13 percent of the world’s biomass. Fungi — yeast, mold and mushrooms — make up about 2 percent. These estimates aren’t very exact, the real numbers could be more or less, but they give a sense of proportion, said study lead author Ron Milo, a biologist at the Weizmann Institute of Science in Israel.

“The fact that the biomass of fungi exceeds that of all animals sort of puts us in our place,” said Harvard evolutionary biology professor James Hanken, who wasn’t part of the study.

Still, humans have an outsized influence on its more massive fellow creatures. Since civilization started, humans helped cut the total weight of plants by half and wild mammals by 85 percent, the study said.

Now domesticated cattle and swines outweigh all wild mammals by 14 to 1, while the world’s chickens are triple the weight of all the wild birds. Instead of children’s books about elephants and lions, a more honest representation of Earth’s animals would be “a cow next to another cow, next to another cow next to a chicken,” Milo said.

Milo and colleagues took earlier research that looked at biomass for different types of life, combined them, factored in climate, geography and other environmental issues, to come up with a planetwide look at the scale of life on the planet. Taking water out of the equation and measuring only dry carbon makes it easier for scientists to compare species. About one-sixth the weight of a human is dry carbon. Humans are about two-thirds water.

“Even though short in numbers, we have managed to throw a lot of sand in the air and mess up a lot of things,” said noted Harvard biologist EO Wilson, who wasn’t involved in the study.

Hanken

Bid to save animals:

Animal and plant species are vanishing at an accelerating pace around the world — sometimes even before we know that they exist — but conservationists are pushing back against the juggernaut of mass extinction.

From captive breeding to satellite tracking; restoring habitats to removing predators; shaming multinationals to nursing baby pandas and orangutans — in all these ways, scientists and others have given a second chance to creatures under threat.

Take the Mauritius kestrel, a svelte and dappled falcon reduced to a population of just four, including one breeding female, in 1974 by a perfect storm of human meddling.

The keen-eyed predator lost much of its natural habitat when settlers clear-cut the Indian Ocean island’s forests in the 18th century.

What pushed the bird to the brink, however, was the widespread use of the pesticide DDT in the 1950s, as well as invasive species such as cats, mongooses and crab-eating macaques with a taste for the birds and their eggs.

But a combination of captive breeding, food supplements, nest improvements and predator control has increased the bird’s numbers to about 400, making it one of the most successful bird restoration projects in history.

On nearby Madagascar, the greater bamboo lemur — aka the broad-nosed gentle lemur — has also made a fairy-tale comeback.

Long thought to be extinct, the dark-furred primate — which has tufted, white-tinged ears — was “rediscovered” in 1986 in the island nation’s southeastern Ranomafana region.

True to its name, the lemur is a “bamboo specialist” that feasts almost exclusively on a single species of the fibrous, quick-growing plant. Scientists are still trying to figure out how the brown-eyed tree-dweller metabolises the quantities of cyanide — enough to kill a human adult — found in a day’s diet of bamboo shoots.

Unfortunately the lemur is still hanging by a “critically endangered” thread, isolated in four percent of its historic range. But the creation of a national park around the area where it was found has boosted its chances of survival.

Across the board, biodiversity is declining. To date, the International Union for the Conservation of Nature (IUCN) has evaluated nearly 80,000 animals and plants, cataloguing their conservation status on its famous Red List of endangered species.

Some 23,000 — nearly a third — are threatened with extinction, including 41 percent of amphibians, 34 percent of conifers, 33 percent of reef building corals, 25 percent of mammals, and 13 percent of birds.

“The sixth mass extinction is happening now,” Craig Hilton-Taylor, head of the Red List, told AFP ahead of the International Day for Biological Diversity on May 22.

Chinese salamander faces

extinction:

The world’s largest amphibians, giant Chinese salamanders, were once thought to be widespread but now face imminent extinction due to illegal poaching and hunting as a luxury food, researchers said Monday.

“The overexploitation of these incredible animals for human consumption has had a catastrophic effect on their numbers in the wild over an amazingly short time span,” said co-author Samuel Turvey, a researcher at the Zoological Society of London.

“Unless coordinated conservation measures are put in place as a matter of urgency, the future of the world’s largest amphibian is in serious jeopardy.”

Vast surveys were conducted in 2013 and 2016 at river sites where the critically endangered salamanders — the size of small alligators and weighing some 140 pounds (64 kilograms) — are known to live.

“We cannot confirm survival of wild Chinese giant salamander populations at any survey sites, and consider the species to be extremely depleted or functionally extinct across the huge surveyed area,” said the report in the journal Current Biology.

China has a program in place to breed and release giant salamanders back into the wild.

At the few sites where salamanders were seen, researchers could not confirm whether they were wild or farmed.

“Our field surveys and interviews indicate the species has experienced catastrophic range-wide decline apparently driven by overexploitation,” said the report.

“The status of wild populations may be even worse than our data suggest. Releases had occurred shortly before surveys at two sites where we detected individuals.”

Researchers also reported that what was once thought of as a single species actually represents at least five distinct species — all speeding toward extinction and some may already be gone.

Furthermore, China’s breed and release approach is illadvised because it does not account for genetic differences in the salamanders, the study said.

Releasing hybrids may mean they are poorly adapted for their individual environments, and unlikely to survive.