Scientists explore deepest parts of Kermadec Trench

Scientists exploring the Kermadec Trench believe they have retrieved the deepest ever sediment sample from the bottom of the ocean using a wire-deployed corer. The sample was obtained at 9994m deep in a mission that took six hours to complete.

The sample was obtained during a three-week voyage to the Kermadec Trench aboard New Zealand’s National Institute of Water and Atmosphere’s (NIWA) flagship research vessel Tangaroa.

The Kermedec Trench is 1500km long and comprises a series of deep basins more than nine kilometres beneath the sea surface. The deepest, Scholl Deep, almost 10km down, was discovered by a Danish research expedition in 1952.

During the latest voyage, scientists in a combined NIWA and University of Southern Denmark expedition, used a range of autonomous deep-diving vehicles as well as traditional sampling approaches.

Prof Ronnie Glud from the University of Southern Denmark, said their work confirmed other recent research suggesting the trenches act as hotspots of intensified biological activity.

“We found that the greatest depths in the Kermadec Trench hosted intensified biological activity, but what was more surprising was the high degree of variability in the metabolic activity among the basins along the trench axis.”

The deep trenches are far more diverse than originally believed.
“If we are to understand the biological and biogeochemical function of the great trenches and their importance for regeneration and sequestration of nutrients and organic carbon in the global ocean, it is of great importance to acknowledge this diversity,” Prof Glud said.

Scientists will now identify the various microbial and faunal communities and seek to explain the variation in the organic carbon processing among the different trench basins. The trenches host unknown and unique life forms that are adapted to extreme pressure.

NIWA marine ecologist, Dr Ashley Rowden, co-leader of the voyage, says the samples and data will help understand how life functions under such conditions, and how it differs from that at shallower depth.

“The deep trenches remain under-studied and represent some of the few spots left to on the globe to be explored. We were really pushing the sampling envelope by attempting to take cores of the seafloor from wire cable-deployed instruments. It took more than one go, but it was worth it,” he said.

The international team on the expedition included researchers from Denmark, Germany, United Kingdom, Chile and New Zealand and was funded by the European Research Council and NIWA.

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