Scientists Track Eels to Their Ocean Breeding Grounds in World-First

NATURE19 October 2022

ByCLARE WATSON

A European eel emerges from sand.

After generations of speculation, scientists have finally managed to track European eels the entire way back to their breeding grounds in the Sargasso Sea – following their movements thousands of kilometers along what is considered one of the most impressive animal migrations in nature.

Scientists are gushing with excitement because this is the first direct evidence of a long-suspected part of the eels' life cycle that was proposed almost 100 years ago.

Until now, no eggs or eels had been found in the North Atlantic Ocean's Sargasso Sea confirming this truly is where eels gather to breed.

"Eels have piqued the curiosity of scientists for millennia," study author and fish biologist Kim Aarestrup of the Technical University of Denmark said on Twitter.

"For the first time ever, we followed eels to their spawning grounds."

Way back in the early 1920s, Danish biologist Johannes Schmidt discovered eel larvae in the Sargasso Sea, far from their freshwater, estuarine, and coastal habitats in Europe and Africa.

Publishing his results in 1923, Schmidt foreshadowed the next century of research to understand how eels reproduce, describing his efforts as "disappointment alternating with encouraging discoveries and periods of rapid progress with others during which the solution of the problem seemed wrapped in deeper darkness than ever."

In the decades since, scientists have been trying to trace the line back to where eels go to breed – a task made harder by the many obstacles in the eels' way: dams, weirs, pollution, habitat loss and overfishing. A sharp decline in European eel (Anguilla anguilla) numbers since the 1980s has only made the task all that much harder, and more urgent.

But don't underestimate these enigmatic creatures. European eels migrate between 5,000 and 10,000 kilometers (3,100 to 6,210 miles) to spawn at sea, after which their larvae drift back towards land and the relative safety of rivers.

Using satellite tags, the researchers behind this latest discovery obtained tracking data from 21 female European eels as they navigated the last leg of their epic journey, southwest from the Azores, a volcanic archipelago in the North Atlantic Ocean, far west of Portugal.

Past research tracking eel migrations had shown eels from all over Europe converge around the Azores islands before departing for the Sargasso Sea, an ocean region bounded by four swirling ocean currents and named for its vast forests of Sargassum seaweed.

The eels were captured, tagged with detachable satellite trackers, swabbed for DNA testing, and released back into the Atlantic Ocean from the Azores islands back in 2018 and 2019.

Six eels reached the Sargasso breeding grounds months later with their satellite trackers still attached; data from 15 other eels were collected along the way. The longest recorded straight-line distance was 2,275 kilometers (1,410 miles).

"Their journey will reveal information about eel migration that has never been known before," says fisheries biologist Ros Wright of the UK Environment Agency, who led the study.

It's still unclear how the eels find their way to the Sargasso Sea or even how long their spawning season extends.

The swimming speed of the eels in this study, which averaged 6.8 kilometers (4.2 miles) a day, and the length of their marathon journey – which takes more than a year – suggests these long-haulers need to make a very calculated migration.

"Rather than make a rapid migration to spawn at the earliest opportunity, European eels may instead make a long, slow spawning migration at depth that conserves their energy and reduces mortality risk," Wright and team write in their published paper.

"This timing would enable the completion of their reproductive maturation before they arrive at the spawning area."

"It's also incredible to know they go way deeper than 1,000 meters on the way!" James Maclaine, a senior fish curator at the UK National History Museum, tweeted. That's plunging more than 3,280 feet down into darkness.

But questions remain over the eels' timing and navigation across thousands of kilometers in open ocean to reach the Sargasso Sea.

It could be that they sense Earth's magnetic fields like Chinook salmon (Oncorhynchus tshawytscha), which return to the exact stream where they hatched. Sniffing out olfactory cues or following ocean currents or temperature fronts are other possibilities, too.

While it might be a while yet before we untangle those threads, for now, this new study completes the map of eel migrations, placing the Azores at the center of conservation efforts to combat the eels' decline.

"This discovery emphasizes the role of the Azores in the life cycle of eels," says study author and fish ecologist José Manuel N. Azevedo from the University of the Azores.

"It will help scientists and conservationists to push for measures to restore eel habitats across the archipelago."

The research was published in Scientific Reports.

 21ST CENTURY ALCHEMY

Scientists Transformed Pure Water Into a Metal, And There's Footage

PHYSICS20 October 2022

ByMICHELLE STARR

The golden sheen on the metallicized water. (Philip E. Mason)

Pure water is an almost perfect insulator.

Yes, water found in nature conducts electricity – but that's because of the impurities therein, which dissolve into free ions that allow an electric current to flow. Pure water only becomes "metallic" – electronically conductive – at extremely high pressures, beyond our current abilities to produce in a lab.

But, as researchers demonstrated for the first time back in 2021, it's not only high pressures that can induce this metallicity in pure water.

By bringing pure water into contact with an electron-sharing alkali metal – in this case an alloy of sodium and potassium – free-moving charged particles can be added, turning water metallic.

The resulting conductivity only lasts a few seconds, but it's a significant step towards being able to understand this phase of water by studying it directly.

"You can see the phase transition to metallic water with the naked eye!" physicist Robert Seidel from Helmholtz-Zentrum Berlin für Materialien und Energie in Germany explained last year when the paper was published.

"The silvery sodium-potassium droplet covers itself with a golden glow, which is very impressive."

Under high enough pressures, pretty much any material could theoretically become conductive.

The idea is that if you squeeze the atoms together tightly enough, the orbitals of the outer electrons would start to overlap, allowing them to move around. For water, this pressure is around 48 megabars – just under 48 million times Earth's atmospheric pressure at sea level.

While pressures exceeding this have been generated in a laboratory setting, such experiments would be unsuitable for studying metallic water. So a team of researchers led by organic chemist Pavel Jungwirth of the Czech Academy of Sciences in Czechia turned to alkali metals.

These substances release their outer electrons very easily, which means they could induce the electron-sharing properties of highly pressurized pure water without the high pressures.

There's just one problem: alkali metals are highly reactive with liquid water, sometimes even to the point of explosivity (there's a really cool video below).

Drop the metal in water and you're going to get a kaboom.

The research team found a very nifty way to solve this problem. What if, rather than adding the metal to water, water was added to the metal?

In a vacuum chamber, the team started by extruding from a nozzle a small blob of sodium-potassium alloy, which is liquid at room temperature, and very carefully added a thin film of pure water using vapor deposition.

Upon contact, the electrons and metal cations (positively charged ions) flowed into the water from the alloy.

Not only did this give the water a golden shine, it turned the water conductive – just like we should see in metallic pure water at high pressure.

This was confirmed using optical reflection spectroscopy and synchrotron X-ray photoelectron spectroscopy.

The two properties – the golden sheen and the conductive band – occupied two different frequency ranges, which allowed them both to be identified clearly.

In addition to giving us a better understanding of this phase transition here on Earth, the research could also allow a close study of extreme high-pressure conditions inside large planets.

In the Solar System's ice planets, Neptune, and Uranus, for example, liquid metallic hydrogen is thought to swirl. And it's only Jupiter in which pressures are thought to be high enough to metallicize pure water.

The prospect of being able to replicate the conditions inside our Solar System's planetary colossus is exciting indeed.

"Our study not only shows that metallic water can indeed be produced on Earth, but also characterizes the spectroscopic properties associated with its beautiful golden metallic luster," Seidel said.

The research was published in Nature.

   

IEA: Surge In Renewables And EVs Has Limited Global Emissions

By Tsvetana Paraskova - Oct 19, 2022

• The growth in carbon dioxide emissions from fossil fuel combustion is expected to be far smaller in 2022 than the year before.
• According to the IEA, a surge in renewable energy and electric vehicles has helped to cap emissions.
• The IEA believes that CO2 emissions this year would be more than three times greater if that surge in renewables and EVs hadn’t taken place.

Carbon dioxide (CO2) emissions from the combustion of fossil fuels globally are expected to rise by just under 1% in 2022, a much smaller increase compared to last year’s thanks to record deployment of renewable energy sources and electric vehicles, the International Energy Agency (IEA) said in a new analysis on Wednesday.  

Last year, CO2 emissions from burning fossil fuels jumped as the global economy began to recover rapidly from the economic crisis triggered by Covid, the IEA said.  

This year, the rise in those emissions will be much smaller, defying expectations of a major jump because of the increased use of coal for power generation amid soaring natural gas prices, the international agency said.

According to the IEA’s analysts of the latest data, CO2 emissions from burning fossil fuels are on track to increase by nearly 300 million tons in 2022 to 33.8 billion tons. The rise of 300 million tons would be “a far smaller rise than their jump” of nearly 2 billion tons in 2021.

“Global CO2 emissions would be set for a 3-times-bigger rise in 2022 – of nearly 1 gigatonne – were it not for a major expansion of solar, wind & EVs,” the IEA’s Executive Director Fatih Birol said.  

“This is contributing to an improvement in the CO2 intensity of global energy supply, resuming a key trend,” Birol added.

“The global energy crisis triggered by Russia’s invasion of Ukraine has prompted a scramble by many countries to use other energy sources to replace the natural gas supplies that Russia has withheld from the market. The encouraging news is that solar and wind are filling much of the gap, with the uptick in coal appearing to be relatively small and temporary,” Birol said in a statement.

The IEA analysis shows that CO2 emissions are growing far less quickly this year than some people feared, he added.

By Tsvetana Paraskova for Oilprice.com

Canada's No. 2 pension fund Caisse sees opportunities in battered bond market

Divya Rajagopal
Thu, October 20, 2022 

FILE PHOTO: The Caisse de depot et placement du Quebec building is seen in Montreal


By Divya Rajagopal

TORONTO (Reuters) - Canada's second largest pension fund Caisse de dépôt et placement du Québec sees opportunities in global fixed income assets after a recent sell-off, and expects global markets to stabilize in the first half of 2023, a top executive said.

"Fixed income assets are definitely more attractive than they were couple of months ago," Caisse's Executive Vice President Vincent Delisle said in an interview on Wednesday.

Caisse, which oversees about C$391.6 billion ($285 billion) in assets, says it sees opportunities in private credit, where where non-banking institutions provide loans to companies.

It plans to continue its push into global fixed income markets, where yields in some pockets have nearly doubled to 7%from 4% last year, while U.S. Treasury bond yields have jumped from zero percent to 4%, said Delisle, who is also head of Caisse's fixed income unit.

"We think fixed income also will catch back its safe haven status when we get a harder landing or global recession in 2023," he said.

Global bond markets have this year witnessed their worst sell-off since 1949 due to hawkish central banks, according to a report by Bank of America in September. Delisle expects bond markets to settle down before stock markets do.

Bond markets suffered a further blow when the British government announced tax cuts last month that were later reversed, leading to a global sell-off of gilts.

Caisse does not have significant exposure to UK and Europe debt markets but is closely watching political instability in UK as it affects its defensive sectors such as currencies, Delisle said.

The current source of discomfort for the markets is central banks fighting inflation, and for the markets to calm down it was imperative to see friendlier central banks, he said.

"To get friendlier central banks, inflation needs to come down and for inflation to come down the growth needs to slow down dramatically," Delisle said.

Delisle is betting that Caisse's diversified portfolio will help it weather the volatility.

About 30% of Caisse's total investments are in fixed income, while public equities make up 28% and private equity accounts for 20% of its investment portfolio. The rest is made up of real estate and infrastructure investments.

The fund reported a negative return of 7.9% in the quarter ending June 2022, with fixed income falling 13% - the steepest fall among its portfolios.

CPP Investments, Canada's largest pension fund, said last week it was seeking bargains after recent market declines.

($1 = 1.3761 Canadian dollars)

(Reporting by Divya Rajagopal, editing by Deepa Babington)