Abundance Of Life At 31K Feet Below The Ocean

Who would have thought that at 31,000 feet below the Ocean, life is amazing. It’s survived everything from asteroid impacts to ice ages to continental drift and simply continued chugging along. It even manages to exist—and flourish—in the deepest part of the world’s oceans, devoid of any sunlight.

Recently, a manned submersible (not a robot, but one with actual people inside) brought this truth into sharp focus by diving over 31,000 feet into the world’s deepest ocean trenches.

The mission—which, over its duration, saw a total of 17 scientists dive down in the sub—ended up finding what might be the largest chemosynthesis-based community on Earth, and uncovered thousands of new species of microorganisms. The results of the study were published in the journal Nature.

To really get a sense of what was down there, the team of researchers took the manned submersible Fendouzhe—the world’s only human-occupied vehicle (HOV) capable of the sampling and research achieved in this study—to depths as extreme as 31,200 feet, in such locations as the Kuril-Kamchatka Trench and the western Aleutian Trench. All in all, they managed to identify 7,564 species of prokaryotic microorganism, over 89 percent of which had never been seen before.

The hadal zone contains some of Earth’s least explored and understood environments. These communities of extreme deep water life forms are sustained not by sunlight—which can’t even begin to penetrate water to hadal-zone depths—but by hydrogen sulfide- and methane-rich fluids found along faults that carve their way through the deep sediment layers found in the trenches.

"Given geological similarities with other hadal trenches, such chemosynthesis-based communities might be more widespread than previously anticipated," the authors wrote. "These findings challenge current models of life at extreme limits and carbon cycling in the deep ocean."

But evidently, even at these extremes, life will win out. The diversity in the trenches is thought to equal that of the rest of the known marine world.

The first humans to descend to some of the deepest points in a variety of trenches were in awe of the experience. And the scientific potential.

"Diving in the submersible was an extraordinary experience—like traveling through time," Mengran Du, a study author and researcher at the Institute of Deep-sea Science and Engineering at the Chinese Academy of Sciences, told Vox. "Each descent transported me to a new deep-sea realm. As a diving scientist, nothing compares to the thrill of gazing through the observation window with my own eyes."

"The presence of these chemosynthetic ecosystems," Du continued, "challenges long-standing assumptions about life’s potential at extreme depths."

Xiao Xiang, convening scientist of the Mariana Trench Environment and Ecology Research and professor at the School of Life Sciences and Biotechnology of Shanghai Jiao Tong University, told China Daily that these deep-sea organisms could be a massive boon for science. "Our research showed the hadal zone microbes exhibit extraordinary novelty and diversity, demonstrating the immense resource potential of the hadal microorganisms in terms of new genes, new structures, and new functions."

"Such resources," Xiang continued, "may provide a new option to solve the dilemma of global depletion of biological resources and also open up prospects for innovative application in the areas of biotechnology, medicine, and energy, among others."