'Living fossil' fish detected with DNA science

Earth’s 'last hiding place’ is being opened up by scientists at Liverpool John Moores University.

The Oceans account for 70% of the planet’s surface and roughly 321 million cubic miles of water (A cubic mile of water is enough to fill 2 million Olympic-size swimming pools).

Until the 1930s species like the ancient coelacanth were thought to be extinct and more species may now be discovered thanks to a technique pioneered by LJMU’s Professor Stefano Mariani, a conservation biologist at LJMU.

Stefano searches seawater for DNA and has made a string of discoveries over a decade by identifying species from tiny particles they leave in their watery wake.

In his latest study, Professor Mariani and his colleagues describe the first detection of “living fossil” coelacanths, (our closest relatives amongst the fishes), using environmental DNA.

He said: “This is an animal that - until 90 years ago - was thought to have gone extinct before the dinosaurs. It is so rare that in South Africa we know a few dozens of individuals by name! Now we have a tool that can rapidly generate a map of its habitats and locations.“

The eDNA approach has also found sharks, rays and whales in ocean locations not known for those animals.

Coelacanth DNA was found in water off South Africa and its presence verified by submersibles. Professor Mariani’s team also found the species in an unexpected location, in the iSimangaliso Marine Protected Area and World Heritage Site, 100 miles of the coast of Durban.

The search was conducted by scientists on the multi-disciplinary Deep Connections project and lead author Ms Jody-Carynn Oliver, of the South African Institute of Aquatic Biodiversity (SAIAB), said: “Detecting coelacanth DNA showcases the powers of this technique in finding rare and elusive species and will enable coelacanth detection in other locations, including currently unchartered areas.

“This is an iconic species. It teaches us about our past and our future. By improving our understanding of its distribution and ecology, we can better safeguard not just its populations but, most importantly, the overall ecosystem that sustains them."

The team included Peter Shum, also of LJMU, Kerry Sink of the South African Biodiversity Institute, Ryan Palmer of SAIAB, and Gwyneth Matcher of Rhodes University.

Their paper Enhancing African coelacanth monitoring using environmental DNA is published today (Oct 23, 2024) in Biology Letters.

Image: African coelacanths have been detected for the first time using environmental DNA. Photo credit: ACEP Deep Connections Project.