Life on the high seas
Photo: Shane Gross (Greenpeace)

THE SARGASSO SEA—Ana Paula, the Esperanza’s officer in charge of the crew and equipment, readies the great white crane to drop the manta trawl into the Sargasso Sea. The trawl’s yellow wings and nearly 10-foot long mesh net that give it the appearance of a manta ray, its namesake, stretch out alongside the Esperanza, a 425-ton ship owned by Greenpeace that has spent the last five months traversing the open seas. The sky over this corner of the Atlantic Ocean near Bermuda is a little gray and the water’s a little rough, but the conditions are safe enough for the ship’s crew to let the trawl glide through the ocean this summer afternoon.

The manta trawl has one mission: to collect microplastic. When the crew brings it back on board after one hour, its little capsule that collects rubbish is full. White, blue, and black tiny bits and pieces of plastic, some as little as 5 millimeters across, fill the filter.

But another color stands out, too: golden yellow. The manta trawl caught bundles of sargassum seaweed along with the plastics. This seaweed is what the Sargasso Sea is named after, and it provides unique habitat and food for hundreds of creatures, including tiny shrimp and endangered sea turtles. It’s an essential part of the ecosystem, and it’s, in part, what these researchers have ventured out on the high seas to study.

There’s a lot scientists don’t know about this seaweed or about the Sargasso Sea, in general. A team of University of Florida scientists, for example, were on the trip to research how much the sargassum heats up compared to the rest of the ocean. They think it might serve as an incubator to help baby turtles grow, and they’re curious about how climate change could affect that dynamic.

Gathering more data—the concentration of microplastics, the role sargassum plays in helping endangered species develop, what animals swim through these warm waters—can help secure protections for the Sargasso Sea, as well as the rest of the world’s oceans. In fact, academics and activists such as Greenpeace have come together to propose a Global Ocean Treaty under the United Nations Convention on the Law of the Sea. Only 1 percent of the world’s oceans are currently protected. The treaty is calling for world leaders to raise that to 30 percent by 2030, a number many scientists and groups, including the International Union for Conservation of Nature, have agreed on is necessary to keep biodiversity and fish populations healthy. The high seas—which make up 63 percent of the world’s oceans area but aren’t owned or managed by any single country—are particularly in need of protection.

That’s the whole reason a team of scientists and activists have hit the high seas. Some people brave the open ocean for the glam and the ‘Gram, but others deal with the incessant sea sickness, sweat-inducing cabins, and months away from family to save the planet.


After a day of rain showers and rough waters, the sky clears up enough for a research excursion off the Esperanza. Several crew members are waiting for me, marine biologist Celia Ojeda, and others in the wet room, where they keep the life vests. Here, crew members crank some wheels and open a watertight door to the open ocean below. A black inflatable motorboat nicknamed Rhino is revving loudly and pushing up against the ship’s green hull.

The terrifying wet room door.
Photo: Greenpeace

Ojeda, who handles the microplastics research for Greenpeace Spain, prepares to board Rhino with a quick glance at the captain for the go-ahead. Her short brown hair tied back out of her face, she quickly climbs down a rope and ladder and, with a final thud, lands in the boat. The rest of us follow behind, me much less gracefully.

With that, we’re off for about an hour on the Sargasso Sea to take eDNA samples. Since the Esperanza set sail, the crew has seen pilot whales, a tiny octopus, and flying fish. The team can only imagine what other wildlife has been swimming beneath them throughout their trip. The eDNA sampling should give them some answers, helping them identify the vertebrates that have passed through the waters over the past 48 hours.

With gloves on the entire time, Ojeda attaches some hoses to a machine that she’ll run for a half-hour. The hose pumps in ocean water, which pulses through the hose, and runs into some small cylinder-shaped glass containers to analyze after the expedition. As we inch closer to the 30-minute mark, the captain lets us know: “20 minutes!” “10 minutes!” When we’re down to just seconds, he shouts, “5 ... 4 ... 3 ... 2 ... 1!” What Ojeda and her colleagues find can hopefully convince some of the world’s leaders that the high seas are worth protecting and with a quickness.

The world’s oceans face a multitude of threats, many of which get worse with each passing year. There’s climate change, which is driving up ocean temperatures globally. By 2100, temperatures may rise by up to more than 7 degrees Fahrenheit. As oceans warm up, so does key habitat for the animals that live there. Corals, for instance, are already suffering from marine heat waves. The oceans also absorb carbon dioxide, which makes the waters more acidic and uninhabitable for shellfish whose shells dissolve at these levels of acidity.

The sargassum frog fish.
Photo: Shane Gross (Greenpeace)

Then there are all the other human activities from mining to fishing to pollution, which the high seas are uniquely vulnerable to. The high seas are legally defined as waters that don’t fall under any single nation’s exclusive economic zone. That means they technically belong to everyone. It also means they’re hard to protect against activities like fishing or mining because they’re beyond any single nation’s jurisdiction, explained Porter Hoagland, a senior research specialist at the Woods Hole Oceanographic Institution.

“Historically, the high seas have been open to a wide array of uses,” he told Earther. “There’s a notion of the freedom of the high seas, and with modern technology—including the ability to get out and use the ocean in those areas, as well as the ability to monitor and enforce—it’s now become increasingly, but not completely, more practical to think about conserving those areas.”

Making the case for conservation is never simple. That’s especially the case for the high seas because scientists haven’t focused their research efforts here historically. Quite frankly the oceans, in general, are still largely a mystery. More than 80 percent of the world’s oceans remain unmapped, unexplored, or unobserved. Without the data or science to show the need for protection, advocates have had a tough time making the case to save it. Yet if oceans aren’t protected, we risk losing a multitude of species forever, including ones we have yet to even discover.

“It’s not possible to think about conservation or think about managing an area or to even know whether an area warrants conservation without some scientific understanding of it,” said Hoagland. “The science is never complete, but we can’t do anything if we don’t know anything about an area.”

The sargassum seaweed makes the Sargasso Sea a particularly unique ecosystem to explore. This sea, in particular, has always been a mystery, sitting along the Bermuda Triangle whose stories of lost sailors and pirates stretch back beyond our time. Now, scientists are trying to demystify it. And they’re finding that despite being far from shore, it’s no oceanic desert. But they’re also finding a shocking amount of pollution intruding on this special place.


Ojeda and Shane Antonition, a research assistant at the Bermuda Aquarium, Museum, and Zoo, piece through the microplastic that the manta trawl has collected. This alone can take up to seven hours sometimes. They use silver tweezers to separate the microplastics from the sargassum, whose roots are like tiny nets. The swaths of sargassum seaweed seem like they can trap nearly anything from a sargassum frogfish that blends almost perfectly with the seaweed to a piece of plastic twine that stands out dramatically.

That’s, in part, what this Greenpeace expedition has been about. In the Sargasso, for instance, it’s clear macro and microplastics have infiltrated the ecosystem. The Sargasso Sea sits within the Northern Atlantic Subtropical Gyre, so the ocean currents that surround the body of water bring in ample amounts of plastic detritus.

One sample from the manta trawl turned up 1,298 fragments of microplastic, which is higher than levels found in the Great Pacific Garbage Patch, the poster child of ocean plastic pollution. Ojeda can’t help but feel worried every time she has to pull these pieces out of the seaweed, which she and Antonition throw back into the ocean when they’re done. This time, the seaweed is plastic-free and safer for wildlife.

“Ten years ago, we were used to seeing images of turtles trapped in plastic or trapped in nets,” Ojeda tells me in her air-conditioned lab on the ship. “The problem now is bigger because the plastic that is in [the ocean] is not seen, so it’s not perceptible for everyone, but it’s causing a lot of damage.”

The method scientists use to sort the microplastics to properly count them.
Photo: Shane Gross (Greenpeace)

This research is essential to securing this international treaty. The team of scientists wants to show how extraordinary the Sargasso Sea is—with its golden rainforest, another name for the giant sargassum mats that allow life to flourish in the middle of the ocean. Really, they want to show how valuable all the oceans are and why a Global Ocean Treaty could save them.


No environmental legal protections cover the high seas. This treaty is the first and only option currently, and there’s really no other alternative if it fails, Fabienne McLellan, the director of international relations for Swiss conservation group OceanCare, told Earther.

This treaty didn’t come out of nowhere. It’s been some 15 years in the making. Now, a draft text finally exists, and world leaders are meeting at the United Nations (UN) in New York until the end of August to talk about every word, sentence, and paragraph until they can get it right.

“This opportunity we have right now is absolutely unique. It is a once-in-a-generation opportunity, really
,” McLellan said. “If we fail and we don’t get this treaty, there really are no other alternatives to protecting the high sea, so it’s very tense, but we are very positive and hopeful that we will achieve this.”

The Global Ocean Treaty covers four specific areas: marine genetic resources (which includes the process countries will follow to share any information or resources gathered from the high seas), environmental impact assessments, area-based management tools (such marine protected areas), and capacity building (which will lay out how countries implement and enforce the treaty). All the negotiating will focus on these four points, McLellan explained. While that can be limiting in what the treaty covers, it does keep the process grounded. Otherwise, McLellan joked officials may be sitting around negotiating for another 30 years.

Still, the process has taken a while. That’s because folks are literally starting from scratch, said Arlo Hemphill, a senior oceans campaigner with Greenpeace USA. As Hemphill explained to Earther, the UN is also big on getting everyone on the same page, and that takes time. Like 15 years’ worth of time. There’s finally enough consensus to get the show on the road. Negotiators are working to finalize treaty language by April 2020. But even if they finish the text, it may still take months after that to get governments to sign off so don’t go celebrating just yet.

The last round of deliberations is set to end by next April, but no one I spoke to imagines that will be the final set of talks. The treaty will likely need more time. Norway, Russia, and South Korea have been most reluctant to sign onto the treaty, Hemphill said. He suspects large-scale commercial fisheries may not be excited about it either. Any industry that could benefit from keeping business as usual—be it the commercial fishing industry or oil and gas giants—is likely to rage against the treaty. Lots of extraction potential remains in the high seas, and what kind of company will just give that up?

A pair of triggerfish find shelter beneath some plastic near sargassum.
Photo: Shane Gross (Greenpeace)

If the treaty can succeed, however, in requiring environmental impact assessments to keep harmful projects out of fragile ecosystems, that’s a major win. Still, that’s a major if. Even if the treaty does succeed, the possibility always remains that nothing will come from it. Look at the Paris Agreement, for instance. It went into force in 2016, yet countries are still moving slowly (if at all) to put forth regulations to meet the climate goals the international agreement lays out. And its non-binding nature has allowed Donald Trump to announce his intent to pull the U.S. out. McLellan said that the Global Ocean Treaty currently contains language to make it legally binding, but the text remains a draft for now.

Still, you only need to spend just a couple days out at sea to notice the way humans are forever impacting it. And really you need just a single cotton candy sunset along the Atlantic Ocean’s horizon to realize that this piece of our planet is worth saving. Though there’s much we cannot see because it sits outside the realm of direct human exploration, it also still deserves to be saved. For without proper protection, this black, deep sea may remain that way, lost to us forever.

Travel and accommodation for this reporting trip was paid for by Greenpeace as part of its mission to inform the public about threats to biodiversity as well as solutions.

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About the author

Yessenia Funes

I mostly write about how environmental policy and climate change intersect with race and class though I occasionally write about animals, science, and art, too. We all need an escape, right?

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