Tuesday 12 December 2017

Well past their shell-by date – 200-year-old oysters found

Paul Melia

Paul Melia

SCIENTISTS have discovered a colony of previously unknown deep-sea oysters which could be more than 200 years old.

Researchers at NUI Galway's Ryan Institute made the startling discovery in the Whittard Canyon some 270km off the south-west coast using a remotely operated submarine capable of descending up to 700 metres.

The scientists discovered a vertical rock face more than half a kilometre beneath the sea surface, which extended upwards for about 150m. To their amazement, it was covered in a rich assemblage of bivalves and corals, which are closely related to oysters.

"Normally when you look at deep sea, you see small things quite far apart," zoologist Dr Louise Allcock told the Irish Independent.

"Imagine an underwater Grand Canyon, where some walls are sloped and some are vertical. We know you sometimes find interesting things when you look at vertical walls.

"We put the ROV (remotely operated vehicle) and discovered big oysters maybe 15cm long. There's no common name for them, but they're like big clams, and they're very big for clams in the deep sea. There was coral and fishes between them, and it was a habitat we wouldn't have expected to see in deep sea.

"We never saw this combination before. What we want to do now is go back to similar places and see if this is a one-off, or a really extensive habitat we haven't seen before."

Experts said it was "really unusual" to see so many animals close together at these depths.

"The bivalves are also remarkably large, and we know that deep-water oysters of this size elsewhere in european seas may be more than 200 years old. So we are probably seeing an exceptionally long-lived and stable community," Professor of Marine Environment at NUI Galway Mark Johnson said.

Irish Independent

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