Scientists prepare for the debate on the oceanic crisis 150 years after the “extraordinary” expedition.

Scientists prepare for the debate on the oceanic crisis 150 years after the “extraordinary” expedition.

Scientists prepare for the debate on the oceanic crisis 150 years after the “extraordinary” expedition.

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In a few days, several hundred researchers will gather in the UK to discuss the crises affecting the oceans and to pay tribute to the expedition that first opened them up for scientific scrutiny.

Exactly 150 years ago, the Challenger expedition began a transformation in our understanding of the seas. It revealed the existence of a myriad of life forms at every depth and showed that the ocean floor was not a shapeless plain, as was then thought, but was dotted with mountain ranges and deep trenches.

“We now know that the oceans play a vital role in guiding the Earth’s chemical, physical and biological processes,” said Nick Owens, director of the Scottish Association for Marine Science. “They are crucial for the health of the planet and today they suffer from multiple threats. Challenger has begun this understanding and it is appropriate to celebrate the 150th anniversary of the expedition by comparing the state of the oceans then and today. “

When Challenger set sail, the seas were hardly affected by global warming; the acidification caused by the absorption of carbon dioxide was not a problem; and the millions of tons of plastic now polluting our seas have remained a distant threat. “The picture of the oceans that was revealed by Challenger provides us with a perfect basis for observing the state of our seas today,” said Owens, who will speak at the Challenger 150 conference opening in London on 6 September.

Challenger sailed from Sheerness in December 1872 with a company of 250 sailors, engineers and Marines, as well as six scientists led by Scottish naturalist Sir Charles Wyville Thomson. Over the next four years, the ship, equipped with a steam engine for dredging, traveled 68,890 nautical miles across the Pacific, Atlantic and southern oceans; she took 133 scoops from the ocean floor; she made 492 deep-sea soundings and made 263 serial observations of the water temperature along her path.

Scientists and supporters of the Challenger Deep Sea Expedition.

Scientists and supporters of the original Challenger deep-sea expedition. Photography: Artokoloro / Alamy

In addition to measuring sea depths, temperatures and currents, the expedition collected marine life from all over the ocean. More than 100,000 species have been collected, preserved and returned to the expedition headquarters in Edinburgh. It took another 20 years to study these specimens, among which more than 4,700 new species of plants and marine life have been discovered. The final report, completed by John Murray after Thomson’s death in 1882, comprised 50 volumes.

“It was an extraordinary achievement,” said marine researcher Adrian Glover of the Natural History Museum, one of the guests at the Challenger 150 conference. “In essence, the Challenger expedition was the first international multidisciplinary scientific project.

“Until then, science tended to be done by individuals working in small laboratories. Challenger changed that. He has covered geology, chemistry, biology and a host of other disciplines. He has led to the birth of international interdisciplinary projects which today constitute the cornerstone of research on topics such as climate change ”.

At the time, most scientists thought the deep ocean floor was completely uniform – a vast flat expanse filled with soft mud, Erika Jones said., curator of navigation and oceanography at the National Maritime Museum, Greenwich.

“Challenger proved that this was absolutely not the case. He is back with these amazing maps showing mountain ranges, valleys and vast trenches deep beneath the waves. The deepest of these is now known as the Challenger Deep. It lies 10,900 meters below the surface of the western Pacific Ocean and is the deepest known point on the surface of the Earth.

It was also thought that the deep ocean could not support life because it was too dark and too cold and the pressures were too great. Challenger changed that vision too, added Jones, whose book, The Challenger Expedition: Exploring the Depths of the Ocean ,will be released in October.

Species discovered by Challenger ranged from tiny mollusks to strange fish such as the little devil watching the stars, Ceratias uranoscopus. However, the Challenger discovery that could have the biggest impact in the coming years didn’t seem dramatic at the time. By dredging the Pacific floor, the expedition unearthed small nuggets of dark material covered with faint indentations. “These were polymetallic nodules and now we know they cover the sea floor by the trillions,” Glover said. The first lump Challenger found is on display at the Natural History Museum, he added.

These nodules are rich in manganese, nickel, cobalt and copper, used to make the electric cars, wind turbines and solar panels needed to replace the carbon-emitting trucks, power plants and factories that destroy our climate. Mining companies say their extraction should be an international priority. By dredging the nodules from the depths, we could help stop the burning of our planet’s devastated surface, they argue.

Many marine scientists disagree. “It’s hard to imagine how seafloor mines can function feasibly without devastating species and ecosystems,” says British marine biologist Helen Scales, a view shared by David Attenborough, who has called for a moratorium on all water-based mining plans. deep.

Along with overfishing and climate change, the issue will be discussed at the conference. Mining companies say it should be relatively easy to vacuum the nodules that cover the sea floor. Many marine biologists disagree. The impact could be catastrophic, they say, although they recognize that this message can be difficult to convey.

“What is scary from a scientific point of view is that it is so difficult to demonstrate to the public how important these environments are to the health of the planet in terms of the global nutrient cycle, carbon capture and maintenance of biodiversity,” said another. keynote speaker, marine chemistry Katherine Duncan, of Strathclyde University.

“The images of the destruction of rainforests have a visceral impact, but those of the ocean floor have no such effect. A sponge is not as photogenic as an orangutan.

Yet the seabed has a lot to offer humanity, Duncan insisted. His search involves a process known as model-based genome extraction that he used to study sediment cores extracted from the ocean floor 4,000 meters deep off the coast of Antarctica.

This work has already revealed the existence of two new species of marine bacteria, Abyssal pseudonocardia And Oceanic pseudonocardiawhich produce antimicrobial compounds and could one day be used to produce new ranges of antibiotics.

Although it is a relatively new science, research on marine organisms has already created dozens of effective drugs. Examples include the sea squirt Ecteinascidia turbinata which attaches to mangrove roots: it was found to have anticancer properties and led to the development of Yondelis, a drug against sarcoma and ovarian cancer. Similarly, a sea snail extract, Magician cone, was used in synthetic form to create Prialt, a chronic pain drug. Corals, sea snails, marine worms and mollusks have also been used to create promising medicines.

“The concern is that if we start deep-sea mining without proper controls, we run the risk of destroying priceless sources of medicines for the future,” Duncan added.

Other threats to ocean health include overfishing. More than 150 million tons of fish are caught each year for human consumption and it is estimated that one third of the planet’s fish stocks are exploited unsustainably.

However, climate change is the ultimate threat, Owens said. “The oceans drive so many planetary processes and are also absorbing most of the heat generated by our fossil fuel emissions. In the end, there is only so much they can take and from what we have learned about impacts over the past 150 years, it is clear that they cannot withstand much more without there being significant impacts on the planet. “

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