Deep ocean species discovered

Abstract

One of the world's deepest ocean trenches has revealed surprises. Nigel Williams reports. One of the world's deepest ocean trenches has revealed surprises. Nigel Williams reports. A new species has been discovered in one of the most remote and inaccessible parts of the ocean previously thought to be entirely free of fish. The new type of snailfish was found living at a depth of 7,000 metres in the Peru-Chile trench of the south-east Pacific Ocean. Mass groupings of cusk-eels and large crustacean scavengers were also discovered living at these depths for the first time, the researchers said. The findings, in one of the deepest parts of the ocean on the planet, were made by a team of marine biologists from the University of Aberdeen, New Zealand and Japan. The team used deep-sea imaging technology to take 6,000 pictures at depths between 4,500 metres and 8,000 metres within the trench. Alan Jamieson, who led the expedition said: “Our findings, which revealed diverse and abundant species at depths previously thought to be void of fish, will prompt a rethink into marine populations at extreme depths.” This expedition was prompted by findings in 2008 and 2009 off Japan and New Zealand when the researchers discovered a new species of snailfish inhabiting trenches there with each trench home to its own species of the fish. “To test whether these species would be found in all trenches, we repeated our experiments on the other side of the Pacific Ocean, some 6,000 miles from our last observations,” said Jamieson. During the three-week expedition of the research vessel Sonne, the researchers used state-of-the-art deep-sea imaging technology, including an ultra-deep free-falling baited camera system, to take images deep into the trench. A species of cusk eel gathered at the camera and fed on the bait for the full day of deployment. “Further research needs to be conducted to decipher whether this is an entirely new species of cusk eel that we have discovered,” the researchers said. The expedition was the seventh to take place as part of Hadeep, a collaborative research project between the University of Aberdeen's Oceanlab, the University of Tokyo's Ocean Research Institute and with support from New Zealand's National Institute of Water and Atmospheric Research (Niwa). The Hadeep team has been investigating extreme depths across the globe for three years. The results have been photographs of the world's deepest-living fish for the first time. The team also discovered a species of amphipod crustacean scavengers which they previously did not know existed at such depths and in such great numbers. Niamh Kilgallen, an amphipod expert from Niwa said: “The sheer abundance of these big amphipods was overwhelming, particularly at 7,000–8,000 metres, which is much deeper than they have been found in any other trench. It begs the question of why and how they can live so deep in this trench but not in any other.” These findings “prompt a re-evaluation of the diversity and abundance of life at extreme depths,” said Jamieson. “Each of the deep trenches across the globe hosts a unique assembly of animals which can differ greatly from trench to trench. The immense isolation of each trench draws parallels with island evolution popularised by Darwin's finches,” he said.