We must learn more about the ocean bottom…before we destroy it

The High Seas Are Being Exploited. Exploration Must Keep Pace.

Jeffrey Marlow for Undark

In 2014, a 300-pound metal contraption was lowered 6 miles beneath the waves of the western Pacific Ocean, through the dark waters of the deepest gash in the Earth’s crust.

When it set down near the bottom of the Mariana Trench, a plume of chalky sediment billowed outward, and rich odors attracted rare species of crustaceans to a baited trap.

It was the first time scientists had visited this site — arguably one of the most inaccessible, wild, and extreme places on the planet — and yet, as the team examined the specimens back in the lab, they discovered something alarmingly familiar.

The samples were full of polychlorinated biphenyl (PCB) — the same carcinogenic pollutant discovered in marine animals around the world, from Europe to Japan.

The study’s implication was as disturbing as it was predictable: human-induced changes to Earth’s ecosystems are outpacing even their initial characterization.

The seas are under threat from all sides: while the toxic cocktail of industrialization and global ocean mixing brings contaminants from factories past and present to waters around the world, more acute threats like intensive fishing and seafloor mining wield environmental wrecking balls on a more local scale.

Seafloor trawling bulldozes intricately tuned habitats at the expense of basic ecosystem functions, while gargantuan deep-sea mining machinery will pulverize hydrothermal vent chimneys when operations ramp up in the coming years.

Despite this onslaught, nearly two-thirds of the ocean — the “high seas,” which fall outside all nations’ exclusive economic zones (EEZs) extending 200 nautical miles from shore — is beyond the reach of any comprehensive legal agreement mandating protection of marine biodiversity and ecosystem functions.

These areas are regulated by an alphabet soup of narrowly defined entities (e.g., ISA, IMO, RFMOs) and are seemingly open for business.

A new series of negotiations may change that, offering a glimmer of hope for marine conservationists. 

Resolution 72/249, adopted by the United Nations General Assembly in December 2017, “decides to convene an intergovernmental conference … to elaborate the text of an international legally binding instrument …on the conservation and sustainable use of marine biological diversity of areas beyond national jurisdiction.”

These words mark the start of a long, arduous political journey. As the grinding machinery of international diplomacy rumbles to life, now is the time to ensure that the best available knowledge is marshalled in support of this international diplomatic effort.

With strong scientific grounding, we must make the case that the benefits of protecting areas of the high seas will outweigh the costs, while simultaneously accelerating baseline measurements and exploration to learn more about this mysterious realm before it is irreparably damaged.

In recent years, countries around the world have been establishing marine protected areas with heightened fervor, buoyed by the economic promise of sustainable resource stocks and ecotourism, and encouraged by the U.N.’s stated mission to protect 10 percent of the global ocean by 2020.

The ecological and climatic underpinnings of these benefits don’t stop at EEZ boundaries, as decades of scientific study have revealed the central role of the high seas in maintaining critical ecosystem services.

For example, phytoplankton incorporate atmospheric carbon dioxide into biomass, providing an estimated $148 billion per year of social benefit from curtailed warming. Fish caught on the high seas are worth $16 billion annually, but might be even more valuable if left alone to seed coastal fisheries.

Seafloor oases like hydrothermal vents support otherworldly life forms secluded from the sun-drenched surface world, and are our best bet for piecing together the conditions that facilitated the origin of life.

These and other assets are not distributed evenly. To ensure that resources are maintained and tipping points are avoided, management decisions need to be tailored to specific services and the conditions needed to maintain them.

Stable fish populations, for example, require large “no-take” reserves that are geographically isolated by deep water, while metal-rich hydrothermal vents are built by roiling fluids emitted at point sources on the seafloor.

Selecting conservation targets and the conditions needed to protect them will require difficult cost-benefit analyses; scientists can help by clarifying the uniqueness, vulnerability, connectivity, and reparability of these assets.

Conservation efforts may be further complicated by our overwhelming ignorance of the high seas. 

Comprising more than 70 percent of the ocean’s volume, these waters contain primary producer microbes whose newly described symbiotic sleight of hand extends habitable zones, and deeper residents that remain virtually unknown due to under-sampling and longstanding collection biases.

We’ve only investigated 0.0001 percent of the deep seafloor in any detail, and most of that has been within EEZs. Based on the fraction of the ocean we have studied, we know there are transformational discoveries and planet-sustaining services in the volumes yet to be explored, but we can’t yet point to the specifics.

In this context, the precautionary principle — to do no harm before we know more — is appealing but challenging to implement.

As illustrated by the PCB-ridden crustaceans in the Mariana Trench, the tendrils of pollution have already reached the deepest, darkest corners of the ocean, and reaching consensus on what constitutes sufficient knowledge is a fractal discussion (we could, of course, always know more) with few real-world demarcations.

Nonetheless, as use of the high seas global commons intensifies, exploration of this largely unseen world must keep pace.

Most scientific expeditions re-visit a handful of relatively well-known sites in order to take advantage of published data and conduct hypothesis-driven research.

Exploration is rarely the remit, and yet the biggest discoveries, from hydrothermal vents to historic shipwrecks, have repeatedly come from such journeys into the unknown. Given the intimidating scope of unexplored seas left to characterize, we need a way to prioritize.

Two strategies should guide our approach: a stout defense implementing ecological triage, and an ambitious offense of targeted exploration. 

Just as emergency doctors must ration medical resources to minimize losses, so too must conservationists focus data collection and advocacy efforts on the most threatened sites, such as tuna fisheries in the western Pacific, or the Lost City hydrothermal field.

To build pre-emptive fences around compelling areas of the high seas, an exploratory workflow of scientific analysis — from broad bathymetric mapping to regional geochemical measurements to localized robotic sampling for lab-based analysis, for example — would clarify areas most likely to provide major findings.

As we enter, complicit, into the “sixth extinction,” we are influencing biomes across the planet before we understand them, precluding the opportunity to catalog, preserve, appreciate, and utilize the full range of Earth’s biodiversity.

This pattern extends to the high seas, and as the U.N. develops a new legal framework for their conservation, the marine science community has a critical role to play. 

We must share the scientific stories of these waters — the engines of our planet that support immense biodiversity and critical climate sustaining processes — emphasizing that protecting the high seas is a boon rather than a burden.

Accelerating scientific exploration, to survey both imminently threatened ecosystems and unseen wonders, will start to fill in the blank spaces on the map.

Given the accelerating pace of high seas exploitation, the opportunity cost of doing nothing — a whale nursery gone unprotected, or a powerful antibiotic gone undiscovered — would be an immense and irreversible loss.

There are simply too many remarkable discoveries on the horizon, and building a strong and scientifically robust basis for conservation will empower future generations to enjoy their benefits.

Jeffrey Marlow is geobiologist, writer, and post-doctoral fellow with Harvard University’s Department of Organismic and Evolutionary Biology. His journalistic work has been published by The New York Times, Wired, and Discover Magazine, among other outlets.