A population of deep-water corals that used to live in the Galápagos disappeared from the fossil record for more than a thousand years, according to a study in PNAS. Although they eventually recovered, the findings suggest that deep-water coral could be more vulnerable to climate change than was previously thought.
Despite their static nature, coral are actually animals. They are keystone species in their ecosystems, where they catch food with tiny tentacles, and sometimes, obtain energy from the symbiotic algae they house. Whilst many coral species live in shallow waters, some are deep-water specialists. Comparatively little is known about these corals, because they’re just so hard to study.
Diving deep in the waters surrounding the Galápagos, researchers collected more than 900 ancient, dead stony corals, from depths of down to 1,000m. Using radiometric dating, they were then able to reconstruct the coral’s ancient history, spanning more than 110,000 years.
The record is one of the most detailed of its kind. It reveals that for tens of thousands of years, the coral did well. They persisted through major global climate events, including the last Ice Age and the subsequent warming that followed. Then, around 5,000 years ago, they vanished from the fossil record, only to reappear around 1,000 years later.
- Evolution experts say wild tomatoes in Galápagos are going 'back in time'
- Charles Darwin saw this Galápagos bird on Floreana Island in 1835, then it wasn't seen again for almost 200 years
The curious case of the disappearing coral was solved when researchers realised that the vanishing trick coincided with a prolonged La Niña event. “During that time, stronger ocean circulation brought deep, nutrient-rich water to the surface, which likely led to lower oxygen levels at depth, making it harder for deep-sea corals to survive,” says Joseph Stewart from the University of Bristol. The coral didn’t go extinct, but they did take a battering it took time to recover from.
Living at depths down to 3km, some had thought that deep-water corals might be more resilient to global warming, which more obviously affects shallow water. The new study challenges that belief.
Looking ahead, climate patterns are expected to change as the planet warms, but by studying how these patterns affected corals in the past, scientists can better predict how deep-sea ecosystems will be impacted in the future.
“Understanding the great antiquity of this ecosystem, its sensitivity to change, and the centuries it takes to recover from disturbance will be vital for conservation efforts,” says Laura Robinson, also from the University of Bristol.
More wildlife stories from around the world
- A remarkable creature lurks in this flooded sinkhole in Mexico. Scientists went in to find it
- Scientists drop cameras 9,100m deep off coast of Japan. What they find baffles them
- Banana-sized deep-sea oddity glows red – and resembles an alien spaceship
- Fungi may survive extreme conditions of Mars and space, say scientists
