Expedition Uncovers 149 New Species in Remote Indian Ocean Seamounts
A deep-sea expedition around the remote Christmas and Cocos islands has revealed remarkable marine biodiversity, documenting 149 species new to science, according to a study published in Deep-Sea Research Part II: Topical Studies in Oceanography in June.
The international research team, led by Tim O'Hara, a marine scientist at Museums Victoria in Melbourne, surveyed volcanic underwater mountains, or seamounts, in the central eastern Indian Ocean. These seamounts, some 40 to 120 million years old and up to 70 kilometers (43 miles) across, had never been studied before.
"People had been around the islands in shallow water before, but no one had looked at life in the deep. It was a massive hole in the data," O'Hara told Mongabay.
The expedition, which involved 33 researchers from institutions in Australia, New Zealand, Canada and the U.S., mapped the seafloor and 22 seamounts in 2020, two years before the area was established as the Indian Ocean Territories Marine Parks. The researchers surveyed depths ranging from 308 to 17,818 feet (94 to 5,431 meters), where conditions are cold, dark and high-pressure with limited food options for benthic species.
Among the new species identified were a sea cucumber from the genus Oneirophanta, a new fish from the greeneye family (Chlorophthalmus), and a parasitic barnacle from the genus Rhizolepas. The team also discovered black corals, sea worms, and a variety of other fish.
At one site they dubbed "The Shark Tooth Graveyard," researchers found around 1,000 shark teeth, covering more than 22 million years of evolution. The teeth included those from great white, mako, tiger, and even Megalodon sharks.
The islands, located southwest of the Indonesian island of Jakarta between Australia and Sri Lanka, are external territories of Australia. Their remote location made the expedition logistically challenging—leaving from Darwin on Australia's northern coast, it took nearly seven days to reach Christmas Island, with Cocos another 600 miles southwest.
The Indian Ocean accounts for about a fifth of global ocean area, with 90% reaching deeper than 3,280 feet. Yet compared to the Pacific and Atlantic, its deep-sea biodiversity remains relatively understudied. Researchers hope this study fills a critical gap.
Scientists stress the importance of exploring these ecosystems as they face growing threats from warming oceans, pollution, overfishing and deep-sea mining. The seamounts also contained polymetallic nodules, which are sought after for deep-sea mining and used in electric vehicle batteries and renewable energy technologies—raising concerns about potential future extraction.
O'Hara and his colleague, Barry, who is a senior scientist at the Monterey Bay Aquarium Research Institute, expressed concerns about these threats, highlighting the need for conservation measures.
The findings underscore the vast unknown biodiversity in the deep ocean and the urgency of studying these habitats before they are impacted by human activities.