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Scientists Warn Of Mass Extinction Of Marine Species

  • Antoine Blua

Coral reefs have been hit hard by ocean acidification, warming, as well as fertilizer and chemical runoff.

Coral reefs have been hit hard by ocean acidification, warming, as well as fertilizer and chemical runoff.

A panel of experts is warning that the oceans are in a worse state than originally thought.

In a new report, experts from various disciplines such as coral-reef ecologists and fisheries scientists conclude that ocean life is "at high risk of entering a phase of extinction of marine species unprecedented in human history."

Carl Gustaf Lundin is the director of the Global Marine and Polar Program at the International Union for Conservation of Nature, which helped produce the report with the International Program on the State of the Ocean (IPSO).

"We've seen five major rounds of extinctions in the past. And they were generally associated with cosmic events like a big strike of a meteorite or massive volcanic eruptions -- things like that," Lundin tells RFE/RL.

"But now we're actually the ones causing this massive decline ourselves. So we are heading into a massive sixth extinction."

Lundin says the team found firm evidence that human-induced impacts such as climate change, overfishing, and nutrient runoff from farming have already caused a dramatic decline in ocean health.

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Multiplier Effect

But more worrying than this, these factors are acting together.

"The combined effects of some of these things are much worse than we previously thought. Certain types of changes in the past -- anything like storm damage for example, nature had an ability to recover from that relatively quickly and bounce back," Lundin says.

"But now, with all these other effects combined, it's much harder for these systems to really recover."

For instance, ocean acidification due to carbon dioxide from the burning of fossil fuels, runoff from nitrogen-rich fertilizer and hormone-disrupting chemicals, overfishing, and warming have all contributed to the mass die-off of corals.

In another example, some pollutants stick to the surfaces of tiny plastic particles that are now found in the ocean bed, increasing the amounts of pollutants consumed by bottom-feeding fish.

The report says the trends are such that a sixth mass extinction is likely to happen -- and far more quickly than any of the previous five.

It notes that previous mass-extinction events have been associated with trends being observed now: depletion of oxygen of seawater, warming, and acidification.

Levels of carbon dioxide being absorbed by the oceans are "already far greater" than at the time of the last great extinction of marine species 55 million years ago, when up to 50 percent of some groups of deep-sea animals were wiped out.

What Can Be Done?

The report's conclusions will be presented at UN headquarters in New York on June 21, when government delegates begin discussions on reforming governance of the oceans.

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Ahead of the talks, Alex Rogers, IPSO's scientific director and professor of conservation biology at Oxford University, has called for an immediate end to exploitative fishing now.

"Deep-sea fisheries in high-sea areas are essentially unmanaged. The regional fisheries management organizations and states simply do not have data on what's being caught," Rogers says.

"There's evidence of systematic misreporting of catches in many cases. In many other cases they just simply don't know what is actually being taken in these fisheries in terms of target and by-catch."

The panel's immediate recommendations also include reducing the input of pollutants including plastics, agricultural fertilizers, and human waste, and making sharp reductions in greenhouse-gas emissions.

with agency reports

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