Ocean prognosis: mass extinction

 

 

Posted 20 June 2011, by Jeremy Hance, Mongabay, mongabay.com

Multiple and converging human impacts on the world’s oceans are putting marine species at risk of a mass extinction not seen for millions of years, according to a panel of oceanic experts. The bleak assessment finds that the world’s oceans are in a significantly worse state than has been widely recognized, although past reports of this nature have hardly been uplifting. The panel, organized by the International Program on the State of the Ocean (IPSO), found that overfishing, pollution, and climate change are synergistically pummeling oceanic ecosystems in ways not seen during human history. Still, the scientists believe that there is time to turn things around if society recognizes the need to change.

“The findings are shocking,” Alex Rogers, IPSO’s scientific director and professor of conservation biology at Oxford University, said in a press release. “As we considered the cumulative effect of what humankind does to the oceans, the implications became far worse than we had individually realized. We’ve sat in one forum and spoken to each other about what we’re seeing, and we’ve ended up with a picture showing that almost right across the board we’re seeing changes that are happening faster than we’d thought, or in ways that we didn’t expect to see for hundreds of years.”

The Earth has seen five mass extinctions, and some scientists suggest we are seeing the signs of a sixth; although usually they point to the destruction of the world’s rainforests as proof, not the degradation of the oceans. However, the panel found that past mass extinctions of marine life included three signs: increased hypoxia or low oxygen levels, increasing ‘dead zones’, and ocean acidification. All three of these are occurring today due to human impacts in addition to overfishing and other issues.

Carbon dioxide, emitted by human activities, is entering the ocean at a rate not seen since the last marine mass extinction around 55 million years ago. Increased carbon sequestered in the oceans leads to acidification (lower pH levels), which is imperiling the world’s coral reefs, threatening algae species, and may doom iconic animals, like the clownfish. The full impacts of acidification are not yet known, but 55 million years ago half of marine species vanished.

In addition, climate change is melting Arctic sea ice and Greenland faster than anticipated, risking not only rising sea levels, but the possibility of methane release from underwater deposits.

Marine dead zones are also on the rise. In 2008 over 400 dead zones were identified globally, but recent research has found that such zones—where dissolved oxygen has fallen to such low levels that most marine species can no longer survive—are doubling every decades. Dead zones are caused by agricultural runoff, especially nitrogen-rich fertilizers, as well as the burning of fossil fuels.

Overfishing has already plundered the oceans of many key marine species. Some target fish and bycatch species (those killed unintentionally) have fallen by 90 percent report researchers. Following the collapse of target fish populations, industrial fisheries simply move onto other species until they too are decimated. Now, both the Arctic and the Antarctic are being eyed by industrial fisheries. The Arctic, which is becoming increasingly assailable due to melting sea ice from climate change, is also a recent target of oil and gas companies.

New research is also showing human trash in marine ecosystems to be more nefarious than expected. Tiny plastic particles are absorbing chemicals, such as flame retardants and synthetic musks, which are then then consumed by marine life. These chemicals have been found as far abroad as the polar seas. Other research has found that plastic decompose in the oceans much faster than expected, releasing potentially toxic substances.

All of these impacts, and others, are not allowing marine ecosystems time to recover, but instead are creating synergistic effects that are putting ocean ecosystems at grave risk.

“The world’s leading experts on oceans are surprised by the rate and magnitude of changes we are seeing. The challenges for the future of the ocean are vast, but unlike previous generations, we know what now needs to happen. The time to protect the blue heart of our planet is now, today and urgent,” says Dan Laffoley, Marine Chair of IUCN’s World Commission on Protected Areas and report co-author said in a press release.

So, how do we prevent a marine mass extinction? Number one, according to the researchers, immediately reduce greenhouse gas emissions. They then recommend restructuring industrial fisheries for longterm sustainability, including shutting fisheries that are not sustainable; establishing more marine protected areas; tackling pollution and nutrient run-off; and reducing oil, gas, and mining in the oceans. The scientists say that the ‘precautionary principle’ must be used in terms of oceanic impacts, in other words society shouldn’t proceed with activities unless they are proven to be largely safe for marine ecosystems. Finally, researchers say the UN General Assembly must more effectively govern and regulate activities in the high seas, which are beyond any national jurisdiction.

According to the report, such large-scale changes are entirely possibly, but “current societal values prevent humankind from addressing them effectively.”

The report’s full findings will be released at the UN in New York later in the week.

 

Created by satellite, the red circles on this map show the location and size of many of our planet’s dead zones. Black dots show where dead zones have been observed, but their size is unknown. Darker blues in this image show higher concentrations of particulate organic matter, an indication of the overly fertile waters that can culminate in dead zones. Image courtesy of NASA. Click on image to enlarge.

http://news.mongabay.com/2011/0620-hance_marine_extinction.html

 

 

About these ads