National Geographic


Deep-Ocean Conservation

The deep sea is the largest ecosystem on Earth, yet it is the least studied and most poorly understood. Humankind rarely visits these abyssal and hadal realms, which is why we still know so little about them. But we do know that they are rich landscapes filled with fantastical geological formations and bizarre-looking animals and that these places, like the unique environments of Yellowstone, the Grand Canyon, and the Everglades, need to be preserved and protected.

Recognizing the need to protect ocean environments, President George W. Bush established three marine monuments in the Pacific Ocean in 2009. Among them was the Marianas Trench Marine National Monument where the DEEPSEA CHALLENGE expedition is headed. Being so far away and hard to reach, you might think these areas are safe from environmental hazards. But their ecological health, along with that of the deep ocean worldwide, is indeed impacted by human activities—and could be even more so in the future. Protecting them is critical.

Scientists suggest that the impact from ocean dumping, unsustainable fishing, overexploitation of mineral resources, global climate change, and even science and exploration is increasing. Litter—ranging from fishing gear tangled at hydrothermal vents to waste dumped into the ocean and bits of plastic that have eroded to resemble sand grains—can make its way to deep-ocean ecosystems. Scientists are studying these effects along with the question of how global climate change is affecting the oceans. Increasing water temperatures, decreasing oxygen concentrations, and reduced pH of the ocean waters will take their toll even in the deepest areas.

Reduced ocean water pH, often called “ocean acidification” (a result of elevated carbon dioxide in the atmosphere, which is absorbed by the ocean) can make it difficult for animals to secrete their shells and skeletons. Marine creatures in shallower waters provide nutrients to deep-sea environments, as dead organisms “rain down” to the bottom. Fewer organisms in shallow waters means less food at the bottom.

Meanwhile, with improved technology and scarcer mineral resources on land, miners are eyeing deep-sea deposits of minerals such as copper, nickel, and cobalt. Unsustainable mining at extreme depths, where life often grows slowly, could have devastating effects on ecosystems. The good news is that some of these impacts can be minimized if steps are taken to manage ocean use. Managers of U.S. marine monuments, for example, can prohibit destructive practices, restore degraded areas, enforce laws, facilitate sustainable uses (including traditional cultural access), and make sure that all exploration is done responsibly.

Deep-sea scientists advise that as technology advances and explorers introduce humankind to the wonders of the deep, a new conservation obligation is developing. Scientists are working to establish best practices for their own work. Already a code of conduct for sampling deep-water hydrothermal vents has been developed. The DEEPSEA CHALLENGE team embraced its own conservation obligation in the Marianas Trench Marine National Monument and worked with the U.S. Fish and Wildlife Service to go over its procedures and secured the proper permits. For example, to avoid transporting species between dive sites—and unknowingly introducing a potentially invasive organism—the expedition team thoroughly rinsed the DEEPSEA CHALLENGER submersible and research landers with fresh water after dives. The likelihood of transporting deep-sea species between sites was low—they probably wouldn’t survive the temperature and pressure changes from the seafloor to the surface—but the team took the precaution nonetheless.

Another risk facing deep-sea environments is the simple fact that people are often unaware of the amazing animals and formations that occupy the deep. Admittedly, you can’t drive to a Pacific marine monument the way you might take a family road trip to Yosemite National Park, but managers of marine monuments hope people become just as captivated by the amazing features of the ocean and value its conservation. To enhance awareness of the Marianas Trench Marine National Monument, managers  hope to establish a visitor center in the Mariana Islands that will showcase the monument’s fascinating features, highlight ongoing scientific research, and inspire the next generation of explorers. Eventually, students and teachers may be able to participate in the research from their classrooms. For information on current ocean education resources visit NOAA’s Ocean Explorer website.

Three other marine monuments in the Pacific also protect fascinating ocean ecosystems. They include the Pacific Remote Islands Marine National Monument in the central Pacific, the Rose Atoll Marine National Monument in American Samoa, and the Papahānaumokuākea Marine National Monument in Hawaii. These monuments are home to millions of seabirds that nest on their islands and feed on their seas; thousands of species of fish, coral, and other invertebrates that depend on their vast shallow and deep ecosystems; and rare and endangered plants and animals that have been lost throughout much of the Pacific. Monument administrators manage and monitor activities and species in these areas to ensure they thrive into the future and that indigenous cultural traditions are perpetuated.

The U.S. marine monuments join other marine protected areas, including Australia’s Great Barrier Reef Marine Park, the Republic of Kiribiti’s Phoenix Islands Protected Area, the Chagos Marine Protected Area in the Indian Ocean, and Chile’s Motu Motiro Hiva Marine Park. All are large sites protecting vast areas of shallow- and deep-ocean habitat. Managers of these large marine protected areas share experiences and lessons learned through the “big oceans” managers’ network to improve management effectiveness, serve as a peer-support system, and build professional standards of practice—with the hope that people across the world will become passionate about ocean conservation and exploration.

Marianas Trench Marine National Monument
Photo Gallery: U.S. Marine Protected Areas

Science Partners

  • Additional major support provided by The Alfred P. Sloan Foundation
  • NASA Jet Propulsion Laboratory
  • Scripps Institution of Oceanography, UC San Diego
  • University of Hawaii at Manoa
  • University of Guam