Timeline (log scale) of marine and terrestrial defaunation. The marine defaunation experience is much less advanced, even though humans have been harvesting ocean wildlife for thousands of years. The recent industrialization of this harvest, however, initiated an era of intense marine wildlife declines. If left unmanaged, we predict that marine habitat alteration, along with climate change (colored bar: IPCC warming), will exacerbate marine defaunation. Graphic: McCauley, et al., 2015

By Carl Zimmer
15 January 2015

(The New York Times) – A team of scientists, in a groundbreaking analysis of data from hundreds of sources, has concluded that humans are on the verge of causing unprecedented damage to the oceans and the animals living in them.

“We may be sitting on a precipice of a major extinction event,” said Douglas J. McCauley, an ecologist at the University of California, Santa Barbara, and an author of the new research, which was published on Thursday in the journal Science.

But there is still time to avert catastrophe, Dr. McCauley and his colleagues also found. Compared with the continents, the oceans are mostly intact, still wild enough to bounce back to ecological health.

“We’re lucky in many ways,” said Malin L. Pinsky, a marine biologist at Rutgers University and another author of the new report. “The impacts are accelerating, but they’re not so bad we can’t reverse them.”

Scientific assessments of the oceans’ health are dogged by uncertainty: It’s much harder for researchers to judge the well-being of a species living underwater, over thousands of miles, than to track the health of a species on land. And changes that scientists observe in particular ocean ecosystems may not reflect trends across the planet.

Dr. Pinsky, Dr. McCauley and their colleagues sought a clearer picture of the oceans’ health by pulling together data from an enormous range of sources, from discoveries in the fossil record to statistics on modern container shipping, fish catches and seabed mining. While many of the findings already existed, they had never been juxtaposed in such a way.

A number of experts said the result was a remarkable synthesis, along with a nuanced and encouraging prognosis.

“I see this as a call for action to close the gap between conservation on land and in the sea,” said Loren McClenachan of Colby College, who was not involved in the study.

There are clear signs already that humans are harming the oceans to a remarkable degree, the scientists found. Some ocean species are certainly overharvested, but even greater damage results from large-scale habitat loss, which is likely to accelerate as technology advances the human footprint, the scientists reported.

Coral reefs, for example, have declined by 40 percent worldwide, partly as a result of climate-change-driven warming.

Some fish are migrating to cooler waters already. Black sea bass, once most common off the coast of Virginia, have moved up to New Jersey. Less fortunate species may not be able to find new ranges. At the same time, carbon emissions are altering the chemistry of seawater, making it more acidic.

“If you cranked up the aquarium heater and dumped some acid in the water, your fish would not be very happy,” Dr. Pinsky said. “In effect, that’s what we’re doing to the oceans.” [more]

Ocean Life Faces Mass Extinction, Broad Study Says


BACKGROUND

Comparing patterns of terrestrial and marine defaunation helps to place human impacts on marine fauna in context and to navigate toward recovery. Defauna­tion began in earnest tens of thousands of years later in the oceans than it did on land. Although defaunation has been less severe in the oceans than on land, our effects on marine animals are increasing in pace and impact. Humans have caused few complete extinctions in the sea, but we are responsible for many ecological, commercial, and local extinctions. Despite our late start, humans have already powerfully changed virtually all major marine ecosystems.

ADVANCES

Humans have profoundly decreased the abundance of both large (e.g., whales) and small (e.g., anchovies) marine fauna. Such declines can generate waves of ecological change that travel both up and down ma­rine food webs and can alter ocean ecosystem functioning. Human harvesters have also been a major force of evolutionary change in the oceans and have reshaped the genetic structure of marine animal populations. Climate change threatens to accelerate marine defaunation over the next century. The high mobility of many marine animals offers some increased, though limited, capacity for marine species to respond to climate stress, but it also exposes many species to increased risk from other stressors. Because humans are intensely reliant on ocean ecosystems for food and other ecosystem services, we are deeply affected by all of these forecasted changes.

Three lessons emerge when comparing the marine and terrestrial defaunation experiences: (i) today’s low rates of marine extinction may be the prelude to a major extinction pulse, similar to that observed on land during the industrial revolution, as the footprint of human ocean use widens; (ii) effectively slowing ocean defaunation requires both protected areas and careful management of the intervening ocean matrix; and (iii) the terrestrial experience and current trends in ocean use suggest that habitat destruction is likely to become an increasingly dominant threat to ocean wildlife over the next 150 years.

OUTLOOK

Wildlife populations in the oceans have been badly damaged by human activity. Nevertheless, marine fauna generally are in better condition than terrestrial fauna: Fewer marine animal extinctions have occurred; many geographic ranges have shrunk less; and numerous ocean ecosystems remain more wild than terrestrial ecosystems. Consequently, meaningful rehabilitation of affected marine animal populations remains within the reach of managers. Human dependency on marine wildlife and the linked fate of marine and terrestrial fauna necessitate that we act quickly to slow the advance of marine defaunation.

Marine defaunation: Animal loss in the global ocean

2 comments :

  1. Survival Acres said...

    Why keep using terms like "precipice" when this is wildly inaccurate?

    Doesn't this indicate that we've NOT gone over the edge? And doesn't the data clearly show that we've long since done that?

    Extinction is forever, and we've now wiped out thousands of species. They're never, ever coming back.

    We're also on the verge of wiping out several (more) large mammals IN THE NEXT COUPLE OF YEARS (extinction, just so I'm very clear). Doesn't this also mean that the term 'precipice' is very inaccurate and misleading?

    How can humanity be on the 'precipice' when humanity has done so much damage already? EXACTLY when do we stop using these stupid terms that carry absolutely no meaning considering the actual facts?

    Seriously. Why don't these stupid scientist face up and fess up the the real FACTS?

    Here is another example of this deliberate watering-down of the facts:

    http://scicasts.com/green-biology/1866-environmental-issues/8860-
    renewable-resources-reach-their-limits/

    Read the link.

    None of their ‘renewable resources’ are actually natural resources.

    Virtually all of them only ‘happened’ by the destruction of natural habitat, to be replaced with a monoculture that supports exceedingly little biodiversity. Which to me means, “none are and never have been, renewable”.

    Therefore, the ‘2006” year is bogus imo. Industrialized civilization has NEVER been part of the renewable cycle and never, ever will be. Calling anything industrialized civilization has done as ‘renewable’ (such as food production) is just stupid.

    So how much of the natural habitat can be destroyed to support expanding civilization? When does this take us over the 'precipice'? And why do these f*cking idiots keep LYING to the world when there is so little time left to start doing something RIGHT?

    This study seems to really be focused on what we have done and it’s relationship to energy extraction. None of the ‘renewable’ food production would have happened on the scale seen without ancient sunshine being pumped, and therefore, this metric is definitely and never has been ‘renewable’.

    Did they even examine related issues such as climate change, ozone, soil depletion / exhaustion on the declining yields per acre?

    Actually, I’m not impressed with the logic behind EITHER of these articles. No offense to the scientists involved, but why call any of this renewable or a precipice at all when it clearly isn’t?

    It's as if these egg-heads have put their brains in park and can only mouth off politically-correct LIES.

    Perhaps that's it... or perhaps they're still totally disconnected from reality like the rest of this f*cked up world of mutant humans who remain 100% convinced that 'self' is all that has ever mattered.  

  2. Anonymous said...

    Blah blah, mass extinction, blah blah.  

 

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