A giant squid has turned up in the deep off Western Australia, at least in DNA.
Scientists led by Curtin University found evidence of the species in deep underwater canyons off the Nyinggulu (Ningaloo) coast, along with a wide range of other marine life that included whales, strange fish and species not previously recorded in Western Australian waters.
The study explored the Cape Range and Cloates submarine canyons, about 1200 kilometres north of Perth. During the expedition, led by the Western Australian Museum aboard the Schmidt Ocean Institute research vessel R/V Falkor, researchers collected more than 1,000 samples from depths down to 4510 metres.
Rather than relying only on cameras or captured animals, the team used environmental DNA, genetic traces released by marine animals into seawater. By analysing those fragments, the researchers identified species living in the deep ocean without directly observing them.
The study identified 226 species across 11 major animal groups, including squid, marine mammals, cnidarians, echinoderms and deep-sea fish.
Among the findings was evidence of the giant squid, Architeuthis dux, in six separate samples collected from both canyons. Researchers also identified deep-diving whale species including the pygmy sperm whale, Kogia breviceps, and Cuvier’s beaked whale, Ziphius cavirostris.
Scientists also detected dozens of species never previously recorded in Western Australian waters, including the sleeper shark, Somniosus sp., the faceless cusk eel, Typhlonus nasus, and the slender snaggletooth, Rhadinesthes decimus.
Lead author Dr Georgia Nester, who conducted the research during her PhD at Curtin University and now works at the Minderoo OceanOmics Centre at The University of Western Australia, said the findings showed how little is known about Australia’s deep-sea environments.
“Finding evidence of a giant squid really captures people’s imagination, but it’s just one part of a much bigger picture,” Dr Nester said.
“We found a large number of species that don’t neatly match anything currently recorded, which doesn’t automatically mean they’re new to science, but it strongly suggests there is a vast amount of deep-sea biodiversity we’re only just beginning to uncover.”
WA Museum head of aquatic zoology and curator of molluscs Dr Lisa Kirkendale said there had only been two previous records of giant squid in Western Australia, with no confirmed sightings or specimens collected for more than 25 years.
“This is the first record of a giant squid detected off Western Australia’s coast using eDNA protocols and the northernmost record of A. dux in the eastern Indian Ocean,” Dr Kirkendale said.
Dr Nester gathered water samples from the ocean surface to depths greater than 4 kilometres. The eDNA analysis was paired with genetic reference material from physical specimens collected by the remotely operated vehicle SuBastian.
Taxonomists identified those specimens, which are now stored in the WA Museum’s Collection and Research Facility for future research.
“The WA Museum contributed expert identification of specimens from the expedition, supporting the development of a local curated genetic reference that strengthened the eDNA analyses,” Dr Kirkendale said.
Dr Nester said eDNA was especially useful for detecting fragile, fast-moving or elusive marine species that may escape traditional nets and underwater cameras.
“These canyons are incredibly rich ecosystems and, until now, they’ve been largely unexplored because of the difficulty of working at such extreme depths,” Dr Nester said.
“With eDNA, a single water sample can tell us about hundreds of species at once.
“That means we can dramatically expand our understanding of deep-water environments in a way that simply hasn’t been possible before.”
The research also found marine life changed significantly with ocean depth, and that neighbouring canyons supported different ecosystems and distinct biological communities.
Senior author Associate Professor Zoe Richards from Curtin’s School of Molecular and Life Sciences said the technology could improve how scientists study and protect deep-sea ecosystems.
“Deep-sea ecosystems are vast, remote and expensive to study, yet they face growing pressure from climate change, fishing and resource extraction,” Associate Professor Richards said.
“Environmental DNA gives us a scalable, non-invasive way to build baseline knowledge of what lives there, which is essential for informed management and conservation.
“You can’t protect what you don’t know exists. The sheer number of discoveries, including megafauna, makes it clear that we still have so much to learn about what marine life lives in the Indian Ocean.”
The fieldwork was supported by the Schmidt Ocean Institute and the Western Australian Museum. The study, “Environmental DNA Reveals Diverse and Depth-Stratified Biodiversity in East Indian Ocean Submarine Canyons,” was published in the journal Environmental DNA.
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