Норе for the high seas

Global leaders have agreed to a landmark treaty that will safeguard marine life in our shared waters

- OLIVE HEFFERNAN

It was in 2000, during a dive in a deep-sea submersible, that scientists stumbled upon a place unlike anywhere else on Earth. From a distance, it looked like an abandoned metropolis, its tall, smoking towers left billowing long after its inhabitants had fled. On closer inspection, the site, located 800m deep in the middle of the Atlantic Ocean, turned out to be teeming with microbes, and the towers, seen in sharp focus, the likely source of their nutrition.

The Lost City is now recognised as a unique hydrothermal ecosystem, where temperatures rise to 40-70°C and calciumrich, alkaline waters spew from seafloor vents, creating carbonate chimney-like structures over time, the largest of which, called Poseidon, reaches 60m tall. Life thrives here: not just microbes, but sponges, crabs and even corals. Scientists believe that the Lost City, with its unusual conditions, could give clues to the necessary precursors for life on Earth and on other planets, and have earmarked it for UNESCO World Heritage status.

Some of the most extraordinary parts of our planet are out of sight. They are also outside the control of any single nation, in the two-thirds of our ocean known as the high seas. Typically starting 200 nautical miles from shore, the high seas cover roughly 43 per cent of our planet’s surface and, with an average depth of 4,000m, they constitute 95 per cent of Earth’s available living space. From their sunlit shallows to their lightless depths, they are home to a rich diversity of creatures and ecosystems, many of which we are only now beginning to appreciate.'

ABOUT THE AUTHOR 

A former marine biologist, Olive Heffernan now works as a lecturer and writer, specialising in ocean science and climate change.