Scripps researcher calls for better care of the deep blue sea

By Chris Palmer

The deep ocean is under attack by climatic and economic forces, and without proper stewardship, this important resource could be irreversibly damaged, warned Scripps Institution of Oceanography Distinguished Professor Lisa A. Levin. She delivered the message recently to a capacity audience at a Jeffrey B. Graham ‘Perspectives on Ocean Science’ lecture hosted by the Birch Aquarium.

Levin’s talk, “A New Imperative for Deep-Ocean Stewardship,” detailed the ways in which changes in ocean temperature and chemistry, as well as growing economic opportunities, are placing new pressures on deep-ocean ecosystems.

Levin has conducted research of deep-ocean ecosystems on the margins of the Pacific, Indian and Atlantic Oceans in more than 30 oceanographic expeditions over the past 3 decades using ships, submersibles and remotely operated vehicles to collect samples and conduct experiments. “The deep ocean covers over half of the planet but most of it is less well known than the surface of the moon,” she said.

In addition to the enormous biodiversity it hosts, the deep ocean provides numerous benefits to humans and the planet as a whole. It is the source of many biological products utilized in industry and medicine. The sea floor is the habitat of bacteria and other microorganisms that are the basis of most marine food chains. The sea floor also performs the vital service of sequestering excess carbon dioxide from the Earth’s atmosphere.

Currently, said Levin, human activity is threatening the deep ocean on a variety of fronts. Climate change will likely increase the amount of carbon dioxide and methane gas in the ocean, leading to ocean acidification and deoxygenation. The result will be a loss of deep-water corals and disruption of all marine ecosystems.

Over the past 40 years, humans have greatly expanded the range of depths in which they fish. This practice is unsustainable due to the low reproductive rates and slow growth of the large fish at those depths. Humans have also increasingly been engaged in bottom trawling, which, according to Levin “leaves a barren wasteland and flat surfaces in its wake.”

Equally damaging in its impact is the mining of the ocean floor, which is starting to occur near the coastal regions of some developing countries. Operations in Namibia and Papua New Guinea will essentially vacuum the ocean floor for scraps of mineral resources, in a process that Levin compared to strip mining.

“There is a need for improved and coordinated stewardship of deep waters,” she said, pointing to the confusion created by the enormous diversity in the regulation of a wide variety of activities, such as fishing and mining, in the deep ocean amongst the more than 120 countries that claim coastal jurisdiction.

Even when regulations are clearly stated, “Enforcement in the deep sea is a major challenge due to lack of resources, though remote sensing technology is starting to help,” said Levin.

Levin ended her lecture with a quote by New York Times writer Verlyn Klinkenborg. “It is not how many species we discover. It is how to protect them once we found them, and how to keep from destroying the species we do not know before we have a chance to find them.”