The warning comes from Jeremy Jackson, a professor at the Scripps Institution of Oceanography in San Diego. He says human impacts are laying the groundwork for mass extinctions in the oceans that could equal the vast ecological upheavals of the past.

Jackson says the dire situation has been brought about by the synergistic effects of habitat destruction, overfishing, ocean warming, increased acidification and massive nutrient runoff. He calls the ongoing transformation of once complex ocean ecosystems into simplistic ecosystems dominated by microbes, algal blooms, jellyfish and disease as "the rise of slime."

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

His assessment of the Earth's oceans and their failing ecological health appears in the online early edition of the Proceedings of the National Academy of Sciences.