"In a time of universal deceit telling the truth is a revolutionary act." -George Orwell

What The Sixth Extinction Will Look Like In The Oceans: The Largest Species Die Off First

In Uncategorized on September 15, 2016 at 11:18 am
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Atlantic bluefin tuna are corralled by fishing nets during the opening of the season in 2011 for tuna fishing off the coast of Barbate, Cadiz province, southern Spain. (AP Photo/Emilio Morenatti, File)

Oldspeak: “The losses the authors describe in the oceans do not include the extinctions expected from business-as-usual climate change.  Adding those human-triggered losses onto those we’re already causing from over-fishing, pollution, and so on is very likely to put the human race in the same class as an asteroid strike–like the one that killed the dinosaurs–as an extinction driver.” -Anthony Barnosky, executive director of Stanford Jasper Ridge Biological Preserve

We live amid a global wave of anthropogenically driven biodiversity loss: species and population extirpations and, critically, declines in local species abundance. Particularly, human impacts on animal biodiversity are an under-recognized form of global environmental change. Among terrestrial vertebrates, 322 species have become extinct since 1500, and populations of the remaining species show 25% average decline in abundance. Invertebrate patterns are equally dire: 67% of monitored populations show 45% mean abundance decline. Such animal declines will cascade onto ecosystem functioning and human well-being. Much remains unknown about this “Anthropocene defaunation”; these knowledge gaps hinder our capacity to predict and limit defaunation impacts. Clearly, however, defaunation is both a pervasive component of the planet’s sixth mass extinction and also a major driver of global ecological change” –Rodolfo Dirzo et Al, “Defaunation In The Anthropocene”

“Yep, sounds about right. New research confirming the findings of prior research indicating that Earth’s 6th Great Mass Extinction event is well under way, and humans’ propensity for completely exterminating other large bodied life-forms for food, their habitats for shelter and natural resources for consumer goods is driving it. And this omnicidal propensity shows no signs of slowing down in any significant way.  Life in the oceans is being extinguished at an astonishing rate. And as ocean temperatures, acidification, and deoxygenation increase, what is already happening will just continue to happen faster. I found it amusing and quite sad, the cognitive dissonance and astonishing denial exhibited by one of the researchers at the end of this piece, leaving readers with a hit of  utterly unfounded hopium when he said “I talked to a couple of people who said they found this a very discouraging result….I tend not to look at it that way. I think there are a lot of reasons to be optimistic about the oceans, because we haven’t impacted them much yet.” Really. REALLY?!?! We haven’t impacted them much yet?!?! Oceanic dead zones are expanding and getting worse, Seabirds are going extinct as result of plastic poisoning, with every seabird having ingested that particular human toxic waste, the source of HALF THE OXYGEN ON EARTH, phytoplankton, are in major peril and dying off due to anthropogenic ocean acidification, the pacific ocean has basically been converted into radioactive waste dump by the ongoing and uncontrolled release of radioactive water from the Fukushima nuclear power plant in Japan…. Buuuut in that researchers’ view, we haven’t impacted the oceans much yet and we should be “optimistic”. Geeeeeet the fuck outa here. WE ARE THE FUCKING GLOBAL MASS EXTINCTION INDUCING ASTEROID! Exactly what the fuck is optimistic about that?!?!” -OSJ

Written By Chris Mooney @ The Washington Post:

We mostly can’t see it around us, and too few of us seem to care — but nonetheless, scientists are increasingly convinced that the world is barreling towards what has been called a “sixth mass extinction” event. Simply put, species are going extinct at a rate that far exceeds what you would expect to see naturally, as a result of a major perturbation to the system.

In this case, the perturbation is us, rather than, say, an asteroid. As such, you might expect to see some patterns to extinctions that reflect our particular way of causing ecological destruction. And indeed, a new study published Wednesday in Science magazine confirms this. For the world’s oceans, it finds, threats of extinction aren’t apportioned equally among all species — rather, the larger ones, in terms of body size and mass, are uniquely imperiled right now.

From sharks to whales, giant clams, sea turtles, and tuna, the disproportionate threat to larger marine organisms reflects the “unique human propensity to cull the largest members of a population,” the authors write.

“What to us was surprising was that we did not see a similar kind of pattern in any of the previous mass extinction events that we studied,” said geoscientist Jonathan Payne of Stanford University, the study’s lead author. “So that indicated that there really is no good ecological analogue…this pattern has not happened before in the half billion years of the animal fossil record.”

The researchers conducted the work through a statistical analysis of a 2,497 different marine animal groups at one taxonomic level higher than the level of species — called “genera.” And they found that increases in an organism’s body size were strongly linked to an increased risk of extinction in the present period — but that this was not the case in the Earth’s distant past.

Indeed, during the past 66 million years, there was actually a small link between smaller body sizes and going extinct, marking the present as a strong reversal. “The extreme bias against large-bodied animals distinguishes the modern diversity crisis from all potential deep-time analogs,” the researchers write.

The study also notes that on land, we’ve already seen the same pattern — and in fact, we saw it first. “Human hunting has been extensive for many thousands of years on land, whereas it’s been extensive for a couple of hundred years in the oceans,” says Payne.

Thus, humans already drove to extinction many land-based large animal species in what has been dubbed the Late Quaternary extinction event as the most recent ice age came to a close..

“These losses in the ocean are paralleling what humans did to land animals some 50,000 to 10,000 years ago, when we wiped out around half of the big-bodied mammal species on Earth, like mammoths, mastodons, saber-tooth cats and the like,” said Anthony Barnosky, executive director of Stanford Jasper Ridge Biological Preserve, who was not involved in the study but reviewed it for the Post. “As a result, terrestrial ecosystems were locked into a new trajectory that included local biodiversity loss over and above the loss of the large animals themselves, and changes in which kinds of plants dominated.”

Barnosky was the co-author of a study published last year that found an “exceptionally rapid loss of biodiversity over the last few centuries, indicating that a sixth mass extinction is already under way.”

A particular problem, says Payne, is that if you take out all the top predators, then the species they used to prey upon can run amok and explode in population, having large reverberating effects on the entire ecosystem.

“The preferential removal of the largest animals from the modern oceans, unprecedented in the history of animal life, may disrupt ecosystems for millions of years even at levels of taxonomic loss far below those of previous mass extinctions,” the authors write.

Interestingly, if climate change was the key driver of species losses, you’d expect a more evenly distributed set of risks to organisms.

“I’ve worked on the Permian mass extinction quite a bit, it shows environmental evidence of ocean warming, ocean acidification, and deoxygenation, the loss of oxygen from seawater,” says Payne. These are the very same threats to the oceans that we’re worried about now due to ongoing climate change. But the Permian extinction, some 250 million years ago, did not feature a selective disappearance of large-bodied organisms, Payne says.

Thus, as previous work has also suggested, the current study underscores ecosystem risks are not being principally driven by a changing climate — yet. Rather, they’re being driven more directly by humans which species hunt and fish, and where they destroy ecosystems to build homes, farms, cities, and much more. But as climate change worsens, it will compound what’s already happening.

“The losses the authors describe in the oceans do not include the extinctions expected from business-as-usual climate change,” said Barnosky. “Adding those human-triggered losses onto those we’re already causing from over-fishing, pollution, and so on is very likely to put the human race in the same class as an asteroid strike–like the one that killed the dinosaurs–as an extinction driver.”

The study emerges even as the U.S. State Department prepares to open its third annual Our Ocean conference, where heads of state and ocean advocates convene to try to protect more and more of the oceans’ area from over-fishing and other forms of despoilment (and climate change). The study should only heighten the focus at that event.

But Payne says that, in a way, the research is in some ways heartening for those who care about ocean conservation – precisely because human-driven large animal extinctions in the sea are not as advanced as they are on land, there is still a huge amount of biological life that we can save.

“I talked to a couple of people who said they found this a very discouraging result,” Payne says. “I tend not to look at it that way. I think there are a lot of reasons to be optimistic about the oceans, because we haven’t impacted them much yet.”

 

 

 

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