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Mass Extinctions Loom in Ocean Habitats, Scientist Warns

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Human impacts are laying the groundwork for mass extinctions in the oceans on par with vast ecological upheavals of the past, a sea scientist warned this week.

Jeremy Jackson, a professor of oceanography at Scripps Institution of Oceanography at UC San Diego, in the photo on the right, believes that overfishing, pollution, and climate change must be addressed to halt the spiral of the world’s oceans into catastrophe.

“Only prompt and wholesale changes will slow or perhaps ultimately reverse the catastrophic problems they are facing,” he said in a paper published by the science journal Proceedings of the National Academy of Sciences

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Jackson came to this conclusion after pulling together a range of separate studies into various aspects of the oceans’ health, including overfishing, nutrient runoff that lead to so-called “dead zones” of low oxygen, increases in ocean warming, and acidification caused by greenhouse gas emissions.

The combination of habitat destruction, overfishing, ocean warming, increased acidification and massive nutrient runoff are creating a grand transformation of once complex ocean ecosystems, Jackson said in the PNAS paper.

“Areas that had featured intricate marine food webs with large animals are being converted into simplistic ecosystems dominated by microbes, toxic algal blooms, jellyfish and disease.”

Jackson describes this as “the rise of slime.”

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During a recent research expedition to Kiritimati, or Christmas Island, Jeremy Jackson and other researchers documented a coral reef overtaken by algae, featuring murky waters and few fish. The researchers say pollution, overfishing, warming waters or some combination of the three are to blame.

 Photo by Jennifer E. Smith/Courtesy Scripps Institution of Oceanography/UC San Diego

 

 “It’s a lot like the issue of climate change that we had ignored for so long. If anything, the situation in the oceans could be worse because we are so close to the precipice in many ways,” Jackson said.

Jackson rated the status of ocean ecosystems.

  • Coral reefs: “Critically endangered” and among the most threatened ecosystems
  • Estuaries and coastal seas: “Critically endangered,” threatened by overfishing and runoff
  • Continental shelves: “Endangered” due to, among other things, losses of fishes and sharks
  • Open ocean: “Threatened” mainly by overfishing.

“Just as we say that leatherback turtles are critically endangered, I looked at entire ecosystems as if they were a species,” Jackson said. “The reality is that if we want to have coral reefs in the future, we’re going to have to behave that way and recognize the magnitude of the response that’s necessary to achieve it.”

Overexploitation, pollution, and climate are the three main “drivers” that must be addressed, Jackson said.

“The challenges of bringing these threats under control are enormously complex and will require fundamental changes in fisheries, agricultural practices and the ways we obtain energy for everything we do,” he said.

“The only way to keep one’s sanity and try to achieve real success is to carve out sectors of the problem that can be addressed in effective terms and get on it as quickly as possible.”

Jackson says in his paper that the following steps, if taken immediately, could reverse the demise of the oceans: Establish marine reserves, enforce fishing regulations, implement aquaculture, remove subsidies on fertilizer use, muster human ingenuity to limit fossil fuel consumption, buy time by establishing local conservation measures.

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