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Giant clams bleach in warm water



This article was originally posted on Hakai magazine, online publication about science and society in coastal ecosystems. Read more stories like this at

Bleaching occurs when a stressed sea creature, most commonly a coral, expels its symbiotic algae and turns ghostly white, often in response to a warming sea. But bleaching doesn’t just affect corals. Giant clams – massive clams that can reach over 1.2 meters in diameter and weigh up to 225 kilograms – can also become discolored. And in a recent study, scientists have learned more about how bleaching destroys these sessile giants, affecting everything from their nutrition to their reproduction.

Giant clams live on coral reefs and are the largest bivalves on Earth. Like corals, giant clams bleach when they are stressed, often in response to excessively warm water. As with coral, a bleached giant clam expels algae called zooxanthellae that live inside it. These algae live in the soft tissues of the clam’s mantle and provide the animal with energy through photosynthesis, leaving the discolored clam with less energy and nutrients. In the worst case, bleaching can kill giant clams due to a lack of food.

Scientists have been studying the bleaching of giant clams for decades. In 1997 and 1998, during a short period of widespread coral bleaching worldwide, corals died at least 32 disparate countries, bleached giant clams have been observed from the Great Barrier Reef in Australia to French Polynesia following a significant rise in water temperatures in the South Pacific. In 2010, similar water temperatures off Koh Man Nai in Thailand also killed dozens of people.

Of the 12 species of giant clams, some are more resistant to heat stress than others. But even if the giant mollusk survives the bleaching, other physiological functions can be severely affected, the scientists found.

Recent Research in the Philippines, wild mollusks, for example, have found that bleaching can prevent them from reproducing. Bleaching reduces the number of eggs that giant clams produce, and the stronger the bleach, the fewer eggs they lay. Playback “requires a lot of energy. So instead of using that energy to reproduce, they just use it for their own survival,” says Sherry Lin Saiko, lead author of the study and a PhD student at Ryukyu University in Japan.

Mei Ling Neo, a marine ecologist and giant clams expert at the National University of Singapore who was not involved in the study, says the work contributes to the story of how climate change may have “impacts on the lifespan of species.”

Overall, she says, we know much more about how climate change is affecting corals than we do about marine species with similar physiologies. “By understanding how other symbiotic species are responding to climate change, each species becomes a unique indicator of how the entire reef ecosystem works.”

It turns out that bleached giant clams are often better at dealing with bleaching than corals. Near Koh Man Nai, 40 percent of the discolored clams changed color after a few months as zooxanthellae repopulated their tissues when temperatures dropped again. Since the 1997-1998 bleaching, more than 95 percent of the 6,300 bleached clams off Australia’s Orpheus Island have recovered.

Giant clams also seem to lend themselves to replenishment. In the Philippines, where the largest species live, Tridacna gigasbecame extinct locally in the 1980s, replenishment brought it back.

“Shellfish are not just an organism,” says Saiko. “It’s not that we just keep them there to be there,” she adds, “they have a lot of benefits and ecosystem services like [boosting] fishing [and] tourism”.


Randomly bouncing planets could be a sign of advanced aliens



Are strange star systems waiting to be discovered?

Yurik Peter/Shutterstock

Planets that orbit at very close distances from their stars can compete for position, remaining in a generally stable configuration for billions of years – long enough to be detected by astronomers. Such star systems may be so unlikely that they can only be created by artificially advanced alien civilizations.

Most planets have their own orbits, but orbital mechanics allows worlds to be close enough to effectively share an orbit, forcing them into a chaotic dance where they…

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Here’s What Caused the Biggest Space Explosion Ever Seen



IJust last October, telescopes detected a gamma-ray burst caused by a black hole collapse that was so powerful. astronomers quickly dubbed it the BOAT, for “Brightest of All Time”. It was a fitting enough nickname for such a sensational outburst, at least not for long. But the BOAT has just been knocked out in second place in terms of power.

According to the new study published V Royal Astronomical Society Monthly Notices a new champion has arrived: the cosmic blast known as AT2021lwx. The explosion, located 8 billion light-years from Earth, has been erupting for three years now, emitting two trillion times the light of our Sun and 10 times the energy of the brightest supernova ever observed.

The very existence of such a formation, never before observed by astronomers, is further evidence that there are completely new kinds of astronomical phenomena that have yet to be discovered. Where there is one AT2021lwx, there may be others – and even more objects not yet imagined, much less seen.

“AT2021lwx is an extraordinary event that does not fit into any general class of transients. [or stellar eruptions]”, wrote the research team. “Further observations and simulations of AT2021lwx are needed to learn more about the scenario that caused the outbreak.”

The eruption was initially spotted by telescopes at the California Institute of Technology. Zwicky Detention Center in 2020, and at first astronomers thought they might witness quasar, an eruption that occurs when gas and dust fall into a supermassive black hole. But quasars tend to fluctuate in energy and brightness, while AT2021lwx turned on its far beams and kept them bright and stable since its discovery.

“At a quasar, we see how its brightness fluctuates up and down over time,” Professor Mark Sullivan of the University of Southampton, co-author of the paper, said in his paper. Royal Astronomical Society Statement. “But looking back over a decade, AT2021lwx was not discovered and then it suddenly emerged as one of the brightest things in the universe, which is unprecedented.”

The next best guess was a supernova, but the light from such stellar explosions usually lasts for months, not years. Further observations were made Last Asteroid Earth Impact Alert System (ATLAS) in Hawaii, which usually scans the skies for dangerous near-Earth objects, but can also make long-range observations by joining the Zwicky Center in an attempt to understand what astronomers have seen.

Since a quasar and a supernova are ruled out, the authors of the paper, led by astronomer Philip Wiseman of the University of Southampton, turned to so-called tidal disruption. This is when a star is pulled into the mouth of a black hole and crushed in the process. But AT2021lwx also had this rhythm, emitting three times as much light as any tidal disruption ever seen, and also lasting much longer.

“We stumbled upon this by accident as our search algorithm flagged it when we were looking for a type of supernova,” Wiseman said in a statement. “Most supernova and tidal disruption events only last a couple of months before disappearing. It was very unusual for something to be bright for more than two years at once.”

read more: Maybe the Universe Thinks. Listen to me

More telescopes are still connected to study AT2021lwx, including NASA’s orbiting telescope. Neil Gerel Swift Observatory, new technology telescope in Chile and Telescope Gran Canaria in La Palma, Spain. With these instruments making their own observations, and ruling out other alternatives, Wiseman and his colleagues concluded that the bright, steady light of AT2021lwx is caused by a massive cloud of gas many thousands of times the size of our Sun. which orbited the black hole and was somehow destroyed – astronomers do not yet know exactly how – causing gas to enter the hole. They estimate that the entire formation is 100 times the size of our solar system and is currently radiating 100 times more energy than the Sun has emitted in its entire 10 billion years of life. It is not known how long it will continue to burn, but its light still streams in our direction.

Wiseman’s team hasn’t finished studying AT2021lwx yet. V Vera Rubin’s Legacy Space and Time Observatory Researchin Chile should go online in the next few years, and astronomers will point the way for this AT2021lwx telescope elsewhere.

“We hope to find more of these events and learn more about them,” says Wiseman. “Perhaps these events, although extremely rare, are so energetic that they are key elements in how the centers of galaxies change over time.” This fact concerns close to home: our own Milky Way has a supermassive a black hole resting at its center.

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The Swiss village of Brienz was evacuated due to the danger of an imminent collapse



The village of Brienz and its church at the foot of a rockfall.

All residents of the tiny Swiss village were evacuated due to the danger of imminent rockfall.

Less than 100 residents of Brienz were given just 48 hours to gather what they could and leave their homes.

Even dairy cows were loaded for departure after geologists warned that a rockfall was imminent.

Two million cubic meters of rock falls from the mountain above, and a rockfall can wipe out a village.

The development has raised questions about the safety of some mountain communities as global warming changes the alpine environment.

Rock has been shifting since the Ice Age, but scientists say the pace has accelerated.

Brienz in the eastern canton of Graubünden is now empty.

The village has been considered geologically hazardous for some time and is built on land that slopes down towards the valley, causing the church’s spire to tilt and large cracks to appear in the buildings.

Brienz village in front of the rockfall area

Some stones have already fallen from the mountainside

View of a crack in a building in the village of Brienz.

View of a crack in a building in the village of Brienz.

As the minutes ticked by, approaching the deadline for departure, even Brienz’s dairy cows were led to safety.

Residents, some young, some old, families, farmers and professional couples, were given two days to leave their homes.

Earlier this week they were asked to evacuate the village by Friday evening.

A man takes a photo of Renato Lisch, a resident of Brienz/Brinzaul under 'Brienzerrutsch' who is leaving while the village is being evacuated

Renato Lisch, a resident of Brienz, is photographed under a village sign before leaving home.


Mountainside on a Friday when all the villages were asked to leave their homes

Switzerland’s Alpine regions are especially sensitive to global warming – as the permafrost high in the mountains begins to melt, the rocks become more unstable.

This particular mountain has always been unstable, but lately the rock has been shifting faster and faster.

Scientists have warned that two million cubic meters of loose rock could fall from the side of the mountain over the village in a few days of heavy rains.

Villagers must now wait in makeshift dwellings for the rock to fall and hope it doesn’t hit their homes.

Checkpoint in front of the village of Brienz

Checkpoint in front of the village of Brienz.

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