The neuston is home to more than blue buttons and bright snails. Erupting through the lawn of blue are crackling purple, red, gold, and yellow strands. These are Portuguese man o’ wars, whose tentacles stretch like lightning from the meadows of blue and pink. And among them, dragons roam.

Small nudibranchs, known as blue sea dragons, feast on blue buttons and man o’ wars, using their winglike cerata to grab and hold onto their tentacled prey. There are sea anemones, barnacles, copepods, color-changing crabs, specialized bacteria, even bugs, all living in this inverted reef in the middle of the open ocean. (Organisms that live exclusively by floating at the surface of the water are called pleuston, while neuston is a broader term, referring generally to the sea-surface ecosystem, which is why I chose to use it here.)

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Just like reefs on the seafloor, this ecosystem does not stand apart from the open ocean around it. The neuston is a nursery for multiple species of larval fish and a hunting ground for paper nautilus octopuses. It supports sunfish, leatherback turtles, and diverse ocean grazers, which frequent these islands, relying on them as a food source. At night, soft-bodied jellies rise up to join the neuston, sparkling like fireflies. But all of this, from the blue sea dragons to the by-the-wind sailors, is in peril.

When I learned about the Ocean Cleanup project’s 600-meter-long barrier with a three-meter-deep net, a wall being placed in the open ocean, ostensibly to collect plastic passively as the currents push water through the net, I thought immediately of the neuston. How will it be impacted? But in the 146 pages of the Ocean Cleanup’s environmental-impact assessment , this ecosystem isn’t mentioned once.

I was disturbed by this omission. Though the neuston isn’t known to many people, it is certainly known to marine biologists. Evidence that the Ocean Cleanup knows about the neuston is clear from a table reporting animals in the vicinity of the Ocean Cleanup deployment area, where both blue buttons and by-the-wind sailors are listed. But the ecosystem itself is never discussed. By omitting the neuston from its assessment, the project is overlooking the habitat it could be impacting most, and there is no sense of what the damage might be. Because the impact report didn’t provide any answers, I went looking for my own.

There are few contemporary reviews of whole-ocean neuston ecosystems. I started with smaller studies on specific animals and worked my way through their references. One reference, in Russian Cyrillic, came up again and again. This made sense. I knew the United States and the U.S.S.R. had both developed extensive oceanographic-research programs after World War II, but each region published in its own language, making overlap difficult. I sat with a librarian for nearly an hour, hunting this study down. Finally, we found it: a 1956 study published in the U.S.S.R., in Russian, by an oceanographer named A. I. Savilov. This led us to another study of his from 1968, mercifully translated into English. Savilov spent his career studying the neuston by conducting extensive surveys all across the Pacific and synthesizing this work into a map of the open-ocean surface ecosystems.