In a few days, several hundred researchers will gather in the UK to debate the crises facing the oceans – and pay tribute to the expedition that first opened them up to 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 all depths and showed that the ocean floor was not a featureless plain, as then thought, but was dotted with mountain ranges and deep trenches.
“We now know that the oceans play a fundamental role in driving the Earth’s chemical, physical and biological processes,” said Nick Owens, director of the Scottish Marine Science Association. “They are crucial to the health of the planet and today they suffer from multiple threats. Challenger began that understanding, and it’s fitting that we mark the 150th anniversary of the expedition by comparing the state of the oceans then and now.
When Challenger set sail, the seas were hardly affected by global warming; acidification caused by absorption of carbon dioxide was not an issue; and the millions of tonnes of plastic that now pollute our seas remained a distant threat. “The picture of the oceans that was revealed by Challenger provides us with a perfect baseline to look at the state of our seas today,” said Owens, who will speak at the Challenger 150 conference which will open. in London on September 6.
Challenger left Sheerness in December 1872 with a company of 250 sailors, engineers and marines – plus six scientists led by Scottish naturalist Sir Charles Wyville Thomson. Over the next four years, the ship, equipped with a steam engine for dredging, sailed 68,890 nautical miles across the Pacific, Atlantic and Southern oceans; took 133 balls from the bottom of the ocean; made 492 deep-sea soundings and made 263 serial observations of water temperature along its route.
Besides measuring depths, temperatures and sea currents, the expedition collected marine life from all parts of the ocean. Over 100,000 species were collected, stored and returned to the expedition’s 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 were discovered. The final report, completed by John Murray after Thomson’s death in 1882, ran to 50 volumes.
“It was an extraordinary achievement,” said marine researcher Adrian Glover of the Natural History Museum, one of the Challenger 150 conference hosts. “Essentially, the Challenger expedition was the first multidisciplinary international science project.
“Until then, science tended to be conducted by individuals working in small laboratories. Challenger changed that. He covered geology, chemistry, biology and a host of other disciplines. This has led to the birth of international interdisciplinary projects that now form the mainstay of research on topics such as climate change.
At the time, most scientists thought the deep seabed was perfectly even: a wide, flat expanse filled with soft mud, said Erika Jones., curator of navigation and oceanography at the National Maritime Museum in Greenwich.
“Challenger showed that was definitely not the case. He came back with these incredible maps which showed mountain ranges, valleys and vast trenches deep beneath the waves. The deepest of them is now known as the name Challenger Deep, it lies 10,900 meters below the surface of the western Pacific Ocean and is the deepest known point on the Earth’s surface.
It was also believed that the deep ocean could not support life because it was too dark and too cold and the pressures were far too great. Challenger also changed that view, added Jones, whose book, The Challenger Expedition: Exploring the Depths of the Ocean ,will be released in October.
The species discovered by Challenger ranged from tiny seashells to strange fish like the star gazing devil ray, Ceratias uranoscopus. However, the Challenger discovery that could have the biggest impact in the years to come seemed undramatic at the time. While dredging the Pacific seabed, the expedition brought back small nuggets of dark material covered with slight indentations. “These were polymetallic nodules, and now we know they litter the seabed by the billions,” Glover said. The first nodule found by Challenger is on display at the Museum of Natural History, 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 stations and factories that are destroying our climate. Mining companies say their extraction should be an international priority. By dredging up nodules from the depths, we could help stop the burning of our planet’s ravaged surface, they argue.
Many marine scientists disagree. “It’s hard to imagine how seabed mines could operate 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 mining. deep sea mining plans.
In addition to overfishing and climate change, the issue will be discussed at the conference. Mining companies say it should be relatively simple to suck up the nodules that litter the seabed. Many marine biologists disagree. The impact could be catastrophic, they say, although they recognize that this message can be difficult to get across.
“What is frightening from a scientific point of view is that it is so difficult to demonstrate to the public how important these environments are for the health of the planet in terms of global nutrient cycling, the capture of carbon and maintaining biodiversity,” said another keynote. lecturer, marine chemist Katherine Duncan, University of Strathclyde.
“Images of the destruction of rainforests have a visceral impact but those of the ocean floor do not. A sponge is not as photogenic as an orangutan.
Still, the seabed has a lot to offer humanity, Duncan insisted. Her research involves a process known as model-based genome mining which she has used to study sediment cores extracted from the ocean floor at 4,000 meters depth off the coast of Antarctica. .
This work has already revealed the existence of two new species of marine bacteria, Abysmal pseudocardia and Oceanic pseudocardiathat make antimicrobial compounds and could one day be used to make new lines of antibiotics.
Although a relatively new science, research on marine organisms has already created dozens of effective drugs. Examples include sea jet Ecteinascidia turbinata which attaches to the roots of the mangrove: it has been discovered to have anti-cancer properties and has led to the development of Yondelis, a drug against sarcoma and ovarian cancer. Similarly, an extract of sea snail, conus mage, was used in synthetic form to create Prialt, a chronic pain medication. Corals, sea slugs, sea worms and molluscs have also been used to create promising drugs.
“The concern is that if we start deep sea mining without proper controls, we run the risk of destroying invaluable sources of medicine for the future,” Duncan added.
Overfishing is another threat to ocean health. More than 150 million tonnes of fish are caught each year for human consumption, and it is now estimated that a third of the world’s fish stocks are exploited unsustainably.
However, it is climate change that is the ultimate threat, Owens said. “The oceans are the source of so many planetary processes and they also absorb most of the heat generated by our fossil fuel emissions. Ultimately, they can’t take much more, and from what we’ve learned about impacts over the past 150 years, it’s clear that they can’t take much more without there being have significant impacts on the planet.