A Window Into the Deep: Studying Rare Cold-Water Corals in a Patagonian Fjord

When most people think of a coral reef, they picture the kind you might snorkel through on holiday—the shallow, charismatic fish-filled tropical reefs threatened by climate change and bleaching. Yet while those reefs garner most media coverage, there’s a much more widespread type of coral ecosystem that’s also at risk: cold-water corals. Worldwide, sixty-five percent of known coral species live in total darkness and near-freezing temperatures up to 6,000 meters below the ocean’s surface, providing refuge for thousands of species of fauna.

Because they can live for tens of thousands of years, grow incredibly slowly, take longer than most corals to reach sexual maturity, and mostly live beyond individual nations' conservation jurisdictions, these corals are both difficult to study and uniquely vulnerable to disturbances like oil exploration, trawl fishing, and deep-sea mining. At the same time, the relative safety of deep, cold water may give these corals a better chance of surviving the hotter and more acidic oceans of the future than tropical reefs. To know for sure, scientists need to better understand their life cycle.

To learn more about these corals and how they’ll respond to changes in the marine environment, scientists are flocking to a fjord in Chilean Patagonia, the only place on earth where, thanks to waters cooled by glacial meltwater and darkened by sediment and tannins, one deep-sea coral species can be found 30 meters below the surface.