In the future, the Antarctic could become a greener place and be colonised by new species. At the same time, some species will likely disappear. 25 researchers recently presented these and many other findings in a major international project, in which they analysed hundreds of articles on the Antarctic published in the past ten years. By doing so, the team have provided an exceptionally comprehensive assessment of the status quo and future of Antarctica and the Southern Ocean that surrounds it.

Never before have researchers arrived at so many new findings on the biological and biochemical processes at work in the Antarctic than in the past ten years. Now 25 experts, led by the Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research (AWI), have analysed and compiled these findings in the project "AnT-ERA".

Having ultimately processed several hundred articles on the Antarctic, the team have now distilled the content into ten core messages addressing a broad range of aspects, e. g. ocean acidification, biodiversity, and the significance of sea ice for various organisms.

"If you look at the timeframe from 1970 to the present, roughly 80 percent of all academic publications on biology and biochemistry in the Antarctic were released between 2010 and 2020. That's what moved us to condense this enormous amount of knowledge into a single article," says marine biologist and project coordinator Julian Gutt from the AWI. The project outcomes have just been published in the journal Biological Reviews.

Increased biodiversity
One major finding is that the waters of the Antarctic are very likely to grow warmer due to climate change, which in turn increases the probability that plant and animal species from warmer regions will migrate to the Antarctic.

In this regard, not just the temperature, but also the future sea-ice cover will be crucial. For example, in the decades to come, the experts expect to see a more intense greening of ice-free coastal areas during the southern summer, as new mosses or lichens migrate.

Initially, there will likely be a rise in biodiversity. However, a prolonged warming would have grave consequences for those species that are adapted to extremely low temperatures. "We believe these species will retreat to the last remaining extremely cold regions of the Antarctic," says Gutt. "That also means we'll need to protect the regions in order to save these species."

Learning to live in acidic waters?
When it comes to ocean acidification, the study's forecast is bleak: by the end of the century, the experts expect the waters of the Antarctic to be extensively acidified. "There can be no doubt that especially those organisms that form calcareous shells are going to have serious problems," Gutt explains. "We can't yet say for certain if they will all go extinct, or if some species will manage to adapt their metabolisms to the new conditions."

A surprising finding from research conducted in the past ten years: the ostensibly docile organisms that live on the floor of the Antarctic Ocean, e.g. some sponges and ascidians, respond rapidly to improved conditions - by growing quickly or reproducing intensively. The downside: they are equally sensitive to poor environmental conditions. Given the major changes that climate change will entail, these species could also be in danger.

Whereas the Antarctic Peninsula, which extends into the South Atlantic, has been warming for some time now, in the past three years the warming, and therefore the loss of sea ice, has spread to East Antarctica. The experts can't yet say whether this is the beginning of a long-term trend, or only a short-term variation. In either case, this change in the physical environmental parameters is troubling, because it could have a substantial impact on the future development of life in the Southern Ocean.

How much CO2 can the Antarctic swallow?
It also remains unclear whether or not the loss of sea ice will mean that the waters of the Antarctic, due to intensified algal growth, absorb more carbon dioxide from the atmosphere. Principally speaking, most experts assume that algal growth increases when sea ice retreats, because the algae e. g. are exposed to more sunlight. Since algae absorb carbon dioxide from the atmosphere via photosynthesis when they grow, this process can improve the ocean's absorption of CO2.

For some time now, simple forecasts have indicated that the algae in Antarctic waters may absorb ca. 25 percent more CO2 if they become completely ice-free in future southern summers. Yet the current study shows that these blanket statements are problematic. According to Gutt: "The publications we analysed make it clear that the situation varies considerably, depending on the geography. But at least we now know which waters and which parameters we need to focus on to find the answers."

Clear-cut messages

The experts chiefly attribute the fact that so many new insights have been gathered in recent years to technological advances - e. g. in molecular biological methods, new ships and stations, and remotely operated underwater vehicles, some of which can even navigate below the ice. In addition, new numerical and conceptual models are helping us to understand interconnections in the ecosystem. In Julian Gutt's view, the study's greatest contribution is the fact that the 25 authors successfully agreed upon ten core messages that succinctly convey the central findings and offer a glimpse of the future.

http://dx.doi.org/10.1111/brv.12679 Modern microbes provide window into ancient ocean https://www.eurekalert.org/pub_releases/2021-01/uoca-mmp010421.php http://www.colorado.edu/news UNIVERSITY OF COLORADO AT BOULDER

BOULDER Step into your new, microscopic time machine. Scientists at the University of Colorado Boulder have discovered that a type of single-celled organism living in modern-day oceans may have a lot in common with life forms that existed billions of years ago--and that fundamentally transformed the planet.

The new research, which will appear Jan. 6 in the journal Science Advances, is the latest to probe the lives of what may be nature's hardest working microbes: cyanobacteria.

These single-celled, photosynthetic organisms, also known as "blue-green algae," can be found in almost any large body of water today. But more than 2 billion years ago, they took on an extra important role in the history of life on Earth: During a period known as the "Great Oxygenation Event," ancient cyanobacteria produced a sudden, and dramatic, surge in oxygen gas.

"We see this total shift in the chemistry of the oceans and the atmosphere, which changed the evolution of life, as well," said study lead author Sarah Hurley, a postdoctoral research associate in the departments of Geological Sciences and Biochemistry. "Today, all higher animals need oxygen to survive."

To date, scientists still don't know what these foundational microbes might have looked like, where they lived or what triggered their transformation of the globe.

But Hurley and her colleagues think they might have gotten closer to an answer by drawing on studies of naturally-occurring and genetically-engineered cyanobacteria. The team reports that these ancient microbes may have floated freely in an open ocean and resembled a modern form of life called beta-cyanobacteria.

Studying them, the researchers said, offers a window into a time when single-celled organisms ruled the Earth.

"This research gave us the unique opportunity to form and test hypotheses of what the ancient Earth might have looked like, and what these ancient organisms could have been," said co-author Jeffrey Cameron, an assistant professor of biochemistry.

Take a breath
You can still make the case that cyanobacteria rule the planet. Hurley noted that these organisms currently produce about a quarter of the oxygen that comes from the world's oceans.

One secret to their success may lie in carboxysomes--or tiny, protein-lined compartments that float inside all living cyanobacteria. These pockets are critical to the lives of these organisms, allowing them to concentrate molecules of carbon dioxide within their cells.

"Being able to concentrate carbon allows cyanobacteria to live at what are, in the context of Earth's history, really low carbon dioxide concentrations," Hurley said.

Before the Great Oxidation Event, it was a different story. Carbon dioxide levels in the atmosphere may have been as much as 100 times what they are today, and oxygen was almost nonexistent. For that reason, many scientists long assumed that ancient microorganisms didn't need carboxysomes for concentrating carbon dioxide.

"Cyanobacteria have persisted in some form over two billion years of Earth's history," she said. "They could have been really different than today's cyanobacteria."

To find out how similar they were, the researchers cultured jars filled with bright-green cyanobacteria under conditions resembling those on Earth 2 billion years ago.

Hurley explained that different types of cyanobacteria prefer to digest different forms, or "isotopes," of carbon atoms. As a result, when they grow, die and decompose, the organisms leave behind varying chemical signatures in ancient sedimentary rocks.

"We think that cyanobacteria were around billions of years ago," she said. "Now, we can get at what they were doing and where they were living at that time because we have a record of their metabolism."

Resurrecting zombie microbes
In particular, the team studied two different types of cyanobacteria. They included beta-cyanobacteria, which are common in the oceans today. But the researchers also added a new twist to the study. They attempted to bring an ancient cyanobacterium back from the dead. Hurley and her colleagues used genetic engineering to design a special type of microorganism that didn't have any carboxysomes. Think of it like a zombie cyanobacterium.

"We had the ability to do what was essentially a physiological resurrection in the lab," said Boswell Wing, a study coauthor and associate professor of geological sciences.

But when the researchers studied the metabolism of their cultures, they found something surprising: Their zombie cyanobacterium didn't seem to produce a chemical signature that aligned with the carbon isotope signatures that scientists had previously seen in the rock record. In fact, the best fit for those ancient signals were likely beta-cyanobacteria--still very much alive today.

The team, in other words, appears to have stumbled on a living fossil that was hiding in plain sight. And, they said, it's clear that cyanobacteria living around the time of the Great Oxygenation Event did have a structure akin to a carboxysome. This structure may have helped cells to protect themselves from growing concentrations of oxygen in the air.

"That modern organisms could resemble these ancient cyanobacteria--that was really counterintuitive," Wing said.

Scientists, they note, now have a much better idea of what ancient cyanobacteria looked like and where they lived. And that means that they can begin running experiments to dig deeper into what life was like in the 2 billion-year-old ocean.

"Here is hard evidence from the geological record and a model organism that can shed new light on life on ancient Earth," Cameron said.

Research paper

Related Links
Helmholtz Centre For Polar And Marine Research
Beyond the Ice Age

Tweet

Thanks for being there; We need your help. The SpaceDaily news network continues to grow but revenues have never been harder to maintain. With the rise of Ad Blockers, and Facebook - our traditional revenue sources via quality network advertising continues to decline. And unlike so many other news sites, we don't have a paywall - with those annoying usernames and passwords. Our news coverage takes time and effort to publish 365 days a year. If you find our news sites informative and useful then please consider becoming a regular supporter or for now make a one off contribution.
SpaceDaily Monthly Supporter $5+ Billed Monthly Option 1 : $5.00 USD - monthly Option 2 : $10.00 USD - monthly Option 3 : $15.00 USD - monthly Option 4 : $20.00 USD - monthly Option 5 : $25.00 USD - monthly Option 6 : $50.00 USD - monthly Option 7 : $100.00 USD - monthly paypal only		SpaceDaily Contributor $5 Billed Once credit card or paypal

NASA's AIM Sees First Night-Shining Clouds of Antarctic Summer
Greenbelt MD (SPX) Dec 22, 2020
Summer in Antarctica is marked by days in which the Sun never sets, balmy temperatures that hover as high as freezing, and electric-blue clouds of ice. NASA's Aeronomy of Ice in the Mesosphere mission - AIM for short - spotted the summer's first noctilucent, or night-shining, clouds on Dec. 8, 2020. In the days that followed, the fine wisps of cloud slowly grew into slight puffs high over Antarctica. Typically, they spin like cotton candy into a mass that blankets the poles, but this season is off ... read more