Connect with us

Science

‘Major discovery’ beneath Antarctic seas: A giant icefish breeding colony – Kathimerini English Edition

Published

 on


As soon as the remotely operated camera glimpsed the bottom of the Weddell Sea, more than 1,000 feet below the icy ceiling at the surface, Lilian Boehringer, a student researcher at the Alfred Wegener Institute in Germany, saw the icefish nests. The sandy craters dimpled the seafloor, each the size of a hula hoop and less than a foot apart. Each crater held a single, stolid icefish, dark pectoral fins outspread like bat wings over a clutch of eggs.

Aptly named icefishes thrive in waters just above freezing with enormous hearts and blood that runs clear as vodka. Their blood is transparent because they lack red blood cells and hemoglobin to transport oxygen throughout the body. Icefishes’ loss of hemoglobin genes was less an evolutionary adaptation than a happy accident, one that has allowed them to absorb the oxygen-rich Antarctic waters through their skin.

The sighting occurred in February 2021 in the camera room aboard a research ship, the Polarstern, which had come to the Weddell Sea to study other things, not icefish. It was 3 a.m. near Antarctica, meaning the sun was out but most of the ship was asleep. To Boehringer’s surprise, the camera kept transmitting pictures as it moved with the ship, revealing an uninterrupted horizon of icefish nests every 20 seconds.

“It just didn’t stop,” Boehringer said. “They were everywhere.”

Half an hour later, Autun Purser, a deep-sea biologist at the same institute, joined Boehringer. On the camera feed, there remained nothing but nests.

“We were like, is this ever going to end?” Purser said. “How come no one has ever seen this before?”

The nests persisted for the entire four-hour dive, with 16,160 recorded on camera. After two more dives by the camera, the scientists estimated the colony of Neopagetopsis ionah icefish stretched across 92 square miles of the serene Antarctic sea, totaling 60 million active nests. The researchers described the site – the largest fish breeding colony ever discovered – in a paper published Thursday in the journal Current Biology.

“Holy cow,” said C.-H. Christina Cheng, an evolutionary biologist at the University of Illinois-Urbana-Champaign, who was not involved with the research. “This is really unprecedented,” she said. “It is crazy dense. It is a major discovery.”

The paper provides “evidence of a complex and so far undescribed benthic ecosystem in the Weddell Sea,” said Mario La Mesa, a biologist at the Institute of Polar Sciences in Bologna, Italy, who was not involved with the research.

“I would not be surprised to find other massive colonies of breeding fishes elsewhere,” said La Mesa, who last year described the same Antarctic icefish species’ nest-guarding behavior from sites near the newly discovered colony.

Each of the newly discovered nests held, on average, 1,735 large, yolky eggs – low fecundity for a fish. An unprotected clutch would prove an easy snack for predators like starfish, polychaete worms and sea spiders, Cheng said. So the males stand sentry to ensure their offspring are not devoured, at least not before they have the chance to hatch, and may clean the nests with their elongated lower jaw, according to Manuel Novillo, a researcher at the Bernardino Rivadavia Museum of Natural Science in Argentina, who was not involved with the research.

About three-quarters of the colony’s nests were guarded by a single fish. The others had eggs but no fish, a fish carcass furred white with bacteria or nothing at all. Near the edges of the colony, many unused or abandoned nests cradled several icefish carcasses, many with starfishes and octopuses feasting on their eyes and soft parts.

“If you die in the fish nest area, you rot there,” Purser said. “But if you die at the edges, then it seems to be everyone grabs you and starts eating you there.”

The researchers observed that the colony occupied an unusually warm patch of deep water, with temperatures up to about 35 degrees Fahrenheit – practically toasty compared to other Antarctic waters.

Although the discovery of the nests contributes to scientists’ understanding of the icefish life cycle, it raises even more questions. How often are the nests built, and are they reused? Do the fish die after the eggs hatch? Or, perhaps the most obvious: “Why there?” Cheng asked.

The authors have no sure answers, only speculations. Maybe the warm deep currents guide the fish to the grounds. Maybe there is a bounty of zooplankton for the fry to devour. Or maybe it’s something else.

But there must be something special about the location of the active colony. Around 31 miles west, the researchers found a patch of seafloor similarly littered with nests: all empty. These nests were abandoned, overtaken by sponges and corals – long-living creatures that take years to grow, Purser said.

Waters above the icefishes’ expansive settlement also host hungry, foraging Weddell seals. When the researchers collected satellite tracking data from seals during the expedition and analyzed it with historical data, they found, unsurprisingly, that the seals dive primarily to the icefish nests. “They’re having a nice dinner,” Purser said.

Before the end of the cruise, the researchers deployed a camera that will photograph the site twice daily for two years, hopefully revealing even more about the life cycle of the icefish. Novillo said he is looking forward to seeing what the camera captures. “It might constitute the first field observation of courtship behavior and/or nest preparation,” he wrote in an email.

New insights into how icefish reproduce and contribute to polar food webs could help manage and conserve populations. The authors argue the new paper provides enough evidence to protect the Weddell Sea under the Convention on the Conservation of Antarctic Marine Living Resources.

“The seafloor is not just barren and boring,” Purser said. “Such huge discoveries are still there to be made, even today in the 21st century.”


This article originally appeared in The New York Times.

Adblock test (Why?)



Source link

Continue Reading

Science

Mars Was Likely A Cold, Wet World 3 Billion Years Ago – IFLScience

Published

 on


Mars is puzzling. From rover and satellite observations we know that it once had plenty of water on its surface, which usually suggests warm and wet conditions. On the other hand, evidence suggests the planet was always pretty chilly, even in the distant past, but it’s not a cold, dry desert either. These two ideas are often at odds, but new research suggests that they could both be true: ancient Mars was likely a frigid world both cold and wet.

Researchers set out to create a model that can explain the perplexing features witnessed on the Red Planet. If the planet wasn’t warm and wet or cold and dry could there be a third option? Publishing their findings in Proceedings of the National Academy of Sciences, they believe that their cold and wet scenario can explain the existence of a vast liquid ocean in the Northern Hemisphere of Mars, extending to its polar region.

However, the model needed to explain both the presence of a liquid ocean and ice-capped regions, like the presence of glacial valleys and ice sheets in the southern highlands.

Planetary scientists studying Mars have found evidence of ancient tsunamis that rocked the Red Planet. If the ocean was frozen due to a very cold climate, these tsunamis would not have happened. But a milder climate would have meant transferring water from the ocean to the land through precipitation. Cold and wet conditions, however, could have existed.

The team used an advanced general circulation model to work out the necessary parameters for this world. They calculated it was possible for an ocean to be stable even if the mean temperature of Mars was below 0°C (32°F), the freezing point of water, 3 billion years ago. They envisioned ice-covered plateaus in the south with glaciers flowing across the plains and returning to the ocean. Rainfall would have been moderate around the shoreline. In this scenario, the ocean surface could be up to 4.5°C (40°F); not tropical but enough for water to stay liquid.

The key to these conditions is all in the air. The atmosphere of Mars today is about 1 percent in density compared to Earth’s own. But, if in the past it was roughly the same and was made of about 10 percent hydrogen and the rest carbon dioxide, this scenario would actually work. Previous analyses have found strong evidence for a thicker atmosphere before it was ripped from the planet by the steady stream of particles from the Sun.

The model is certainly compelling in explaining the peculiarities of Mars, but of course, much more evidence is needed to understand what the Red Planet was really like billions of years ago.

Adblock test (Why?)



Source link

Continue Reading

Science

Explainer-Scientists struggle to monitor Tonga volcano after massive eruption

Published

 on

Scientists are struggling to monitor an active volcano that erupted off the South Pacific island of Tonga at the weekend, after the explosion destroyed its sea-level crater and drowned its mass, obscuring it from satellites.

The eruption of Hunga-Tonga-Hunga-Ha’apai volcano, which sits on the seismically active Pacific Ring of Fire, sent tsunami waves across the Pacific Ocean and was heard some 2,300 kms (1,430 miles) away in New Zealand.

“The concern at the moment is how little information we have and that’s scary,” said Janine Krippner, a New Zealand-based volcanologist with the Smithsonian Global Volcanism Program.

“When the vent is below water, nothing can tell us what will happen next.”

Krippner said on-site instruments were likely destroyed in the eruption and the volcanology community was pooling together the best available data and expertise to review the explosion and predict anticipated future activity.

Saturday’s eruption was so powerful that space satellites captured not only huge clouds of ash but also an atmospheric shockwave that radiated out from the volcano at close to the speed of sound.

Photographs and videos showed grey ash clouds billowing over the South Pacific and metre-high waves surging onto the coast of Tonga.

There are no official reports of injuries or deaths in Tonga https://www.reuters.com/business/environment/impact-assessment-aid-efforts-underway-world-responds-tonga-tsunami-2022-01-16 yet but internet and telephone communications are extremely limited and outlying coastal areas remain cut off.

Experts said the volcano, which last erupted in 2014, had been puffing away for about a month before rising magma, superheated to around 1,000 degrees Celsius, met with 20-degree seawater on Saturday, causing an instantaneous and massive explosion.

The unusual “astounding” speed and force of the eruption indicated a greater force at play than simply magma meeting water, scientists said.

As the superheated magma rose quickly and met the cool seawater, so did a huge volume of volcanic gases, intensifying the explosion, said Raymond Cas, a professor of volcanology at Australia’s Monash University.

Some volcanologists are likening the eruption to the 1991 Pinatubo eruption in the Philippines, the second-largest volcanic eruption of the 20th century, which killed around 800 people.

The Tonga Geological Services agency, which was monitoring the volcano, was unreachable on Monday. Most communications to Tonga have been cut after the main undersea communications cable lost power.

LIGHTNING STRIKES

American meteorologist, Chris Vagasky, studied lightning around the volcano and found it increasing to about 30,000 strikes in the days leading up to the eruption. On the day of the eruption, he detected 400,000 lightning events in just three hours, which comes down to 100 lightning events per second.

That compared with 8,000 strikes per hour during the Anak Krakatau eruption in 2018, caused part of the crater to collapse into the Sunda Strait and send a tsunami crashing into western Java, which killed hundreds of people.

Cas said it is difficult to predict follow-up activity and that the volcano’s vents could continue to release gases and other material for weeks or months.

“It wouldn’t be unusual to get a few more eruptions, though maybe not as big as Saturday,” he said. “Once the volcano is de-gassed, it will settle down.”

 

(Reporting by Kanupriya Kapoor; Editing by Jane Wardell and Michael Perry)

Continue Reading

Science

Astronauts at Risk of 'Space Anemia' | Health | thesuburban.com – The Suburban Newspaper

Published

 on


MONDAY, Jan. 17, 2022 (HealthDay News) — Astronauts can develop a condition called space anemia because their bodies destroy more red blood cells than normal when in space, a groundbreaking study shows.

Assessments of 14 astronauts over six months between space missions found that 54% more blood cells were destroyed while they were in space than when they were on Earth, according to findings published Jan. 14 in Nature Medicine.

“Space anemia has consistently been reported when astronauts returned to Earth since the first space missions, but we didn’t know why,” said lead author Dr. Guy Trudel of the Ottawa Hospital Research Institute in Canada. “Our study shows that upon arriving in space, more red blood cells are destroyed, and this continues for the entire duration of the astronauts’ mission.”

Before this study, it was believed that space anemia was due to fluid shifting into an astronaut’s upper body upon arrival in space.

Astronauts lose 10% of the liquid in their blood vessels this way. It was thought that their bodies rapidly destroyed 10% of their red blood cells to restore the balance, and that red blood cell control returned to normal after 10 days in space.

But this study found that red blood cell destruction is a primary effect of being in space, not just the result of fluid shifts.

On Earth, our bodies create and destroy 2 million red blood cells every second. But the astronauts in this study — both male and female — destroyed 3 million every second while in space.

Five of 13 astronauts in the study were clinically anemic when they returned to Earth. One of the 14 did not have blood drawn on landing.

More from this section

The researchers also found that space anemia is reversible, with red blood cells levels progressively returning to normal three to four months after astronauts returned from space.

“Thankfully, having fewer red blood cells in space isn’t a problem when your body is weightless,” Trudel said in a hospital news release. “But when landing on Earth and potentially on other planets or moons, anemia affecting your energy, endurance and strength can threaten mission objectives. The effects of anemia are only felt once you land, and must deal with gravity again.”

The findings could be prove useful for patients who develop anemia after long illnesses that require bed rest. Bed rest has been shown to cause anemia, but how it does so is unknown.

The mechanism may be like what occurs in space anemia, according to Trudel, who plans to investigate this theory in future research.

More information

The American Academy of Family Physicians has more on anemia.

SOURCE: The Ottawa Hospital, news release, Jan. 14, 2022

Adblock test (Why?)



Source link

Continue Reading

Trending