Ecosystems on the Endangered List

Stark new assessment warns of mass extinctions and the 'rise of slime'

When certain species have been decimated to the point of joining the endangered species list, measures are taken to more effectively conserve and revive their population bases.

To Jeremy Jackson, ocean ecosystems around the globe similarly have been degraded to the point that they should also be considered “endangered.”

“Just as we say that leatherback turtles are critically endangered, I looked at entire ecosystems as if they were a species,” said Jackson, a Scripps Institution of Oceanography at UC San Diego professor of oceanography.

In his new assessment, published in the Proceedings of the National Academy of Sciences, Jackson reviews and synthesizes a range of research studies focusing on marine ecosystems and their health. The result is a sobering depiction of how human activities are damaging the quality of marine habitats and their environments.

Jackson, director of the Scripps Center for Marine Biodiversity and Conservation, cites the effects of habitat destruction, overfishing, ocean warming, increased acidification, and massive nutrient runoff as culprits in a grand transformation of once-complex ocean ecosystems. 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 has labeled the ongoing transformation “the rise of slime.”

Jackson believes human impacts are laying the groundwork for mass extinctions in the oceans comparable with immense ecological disturbances known from the ancient past through fossil records. His new study discusses the deleterious effects of overfishing, as well as threats from pollution sources such as nutrient runoff that lead to so-called “dead zones” of low oxygen. He also incorporates increases in ocean warming and acidification resulting from greenhouse gas emissions.

“All of the different kinds of data and methods of analysis point in the same direction of drastic and increasingly rapid degradation of marine ecosystems,” Jackson indicates in the paper.

He furthers his analysis by constructing a chart of marine ecosystems and their “endangered” status. Coral reefs, Jackson's primary area of research, are “critically endangered” and among the most threatened ecosystems; also critically endangered are estuaries and coastal seas, threatened by overfishing and runoff; continental shelves are “endangered” due to, among other things, losses of fishes and sharks; and the open ocean ecosystem is listed as “threatened” mainly through losses at the hands of overfishing.

To stop the worldwide downslide, and perhaps one day reverse it, Jackson believes that immediate and far-reaching changes are necessary. He singles out overexploitation, pollution, and climate change as the three main “drivers” that must be addressed.

“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,” he 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.”

—Mario C. Aguilera

October 2008