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New basic research centre

Ready to explore the hadal zones: Inauguration of basic research centre for deep-sea research

With a budget of DKK 54.6 million from the Danish National Research Foundation, deep-sea researchers are busy preparing expeditions to the deepest places on the planet: the hadal trenches.

By Birgitte Svennevig, , 11/12/2020

The hadal trenches, which can be up to 11,000 metres deep, are without doubt some of the least explored sites on Earth. In fact, more people have walked on the Moon than visited the bottom of the largest hadal trenches.

Many people think of the trenches as dark places void of any life. However, recent research has shown that there is actually a surprisingly high amount of biological activity going on down there: the trenches are outright hotspots for microbial life and decomposition of organic matter.

On his expeditions, Professor Ronnie N. Glud from the University of Southern Denmark has explored several of the trenches, and he is now set to head the new centre for basic research HADAL, which will continue this work.

Without the microbes of the hadal zones, we would not exist

- The hadal trenches act as a storage centre for oceanic matter, and when we first examined a hadal trench, we were surprised at how much organic matter had settled there, as well as the abundance of life and biological activity. This kind of life is largely unexplored, and it is more the rule than the exception that we discover new abyssal species. We are now going to examine in more detail how life works under the extreme pressure in the deepest parts of the oceans, he says.

Many deep-sea processes affect the climate and life on Earth. For example, the microbial decomposition of organic matter in the deep-sea sediments is of great significance for the oxygen and carbon dioxide levels on Earth.

- The average depth in the abyssal zones is 3,800 metres, and the deep sea is the domain of bacteria. There are an infinite number of and a variety of microorganisms in the seabed, and the activity level of the bacteria and the processes they facilitate are crucial to the overall element cycles. So, if you want to understand the interaction between chemistry and life in the oceans and on Earth, microorganisms are impossible to ignore, says Ronnie N. Glud.

Pollution also ends up in the hadal trenches

It is not only the organic matter that finds its way down to the bottom of the trenches. So do environmentally hazardous substances.

Facts about the deep sea and hadal trenches

  • Named after Hades, the realm of the dead in Greek mythology, the deepest sections of the oceans are called the hadal zone and range from a depth of 6,000 to 11,000 metres.
  • Most hadal trenches are located in the Pacific Ocean and are the result of subduction; the convergence of tectonic plates. These trenches can be thousands of kilometres long and 20-60 kilometres wide.
  • The deepest place on Earth is the Challenger Deep in the Mariana Trench, which is almost 11,000 metres deep.

- For example, hadal crustaceans contain very high concentrations of environmentally hazardous substances such as PCBs, and we have found high concentrations of mercury in hadal sediments. So, it is not only algae, dead animals and plants that accumulate at the bottom of the trenches. We do not know what happens to the environmentally hazardous substances, and this issue is among the focal points of our future work.

The trenches act like a funnel: Particles and matter from the surface descend along the sides of the trenches and concentrate in the trench itself. This process is strongly stimulated by seismic activity such as earthquakes, where the mudslides, teeming with life, collapse and end up at the bottom of the trenches, while subsequent tsunamis transport vast amounts of matter from land and the coastal zone out to the open sea, where it accumulates in the hadal trenches, among other places.

Due to corona restrictions, the inauguration of HADAL will take place virtually via Zoom.

Meet the researcher

Professor Ronnie N. Glud from the Department of Biology has a large number of expeditions to hadal trenches under his belt.


Facts about the new research centre

  • The Danish Center for Hadal Research (HADAL) is funded by the Danish National Research Foundation, which has contributed with DKK 54.6 million for six years of work, with a possibility of extension for another four years.
  • The next expedition is headed for the Izu-Bonin Trench in the western Pacific, a day’s sailing from Tokyo. It is 9,780 metres at its deepest.
  • 6 senior researchers and about twenty younger researchers, PhD students and technicians will initially be affiliated with the centre.
Editing was completed: 12.11.2020