Fossils purported to be world’s earliest animals revealed as algae

Nov. 23 (UPI) — Fossils previously heralded as the earliest evidence of animal life have been revealed to be algae. The reinterpretation, announced Monday in the journal Nature Ecology and Evolution, will force scientists to reconsider early animal evolution.

“It brings the oldest evidence for animals nearly 100 million years closer to the present day,” study co-author Lennart van Maldegem said in a news release.

“We were able to demonstrate that certain molecules from common algae can be altered by geological processes — leading to molecules which are indistinguishable from those produced by sponge-like animals,” said van Maldegem, a postdoctoral research fellow at the Australian National University.

The new research reverses the trend of fresh discoveries pushing the emergence of animal life further and further back on the evolutionary timeline.

For decades, scientists have struggled to pinpoint the origins of animal life, but recently, a series of discoveries suggested sponge-like animals began proliferating in Earth’s oceans during the Ediacaran Period, as many 635 million years ago.

“Ten years ago, scientists discovered the molecular fossils of an animal steroid in rocks that were once at the bottom of an ancient sea in the Middle East,” said study co-author Jochen Brocks.

“The big question was, how could these sponges have been so abundant, covering much of the seafloor across the world, but leave no body fossils?” said Brocks, an ANU professor.

It turns out, sponges weren’t abundant — they didn’t exist yet.

Though it’s true that sponges remain the only organisms that produce the steroids of note, the latest research suggests ocean chemistry can convert algae sterols into ‘animal’ sterols.

“These molecules can be generated in the lab when simulating geological time and temperatures, but we also showed such processes did happen in ancient rocks,” said ANU researcher Ilya Bobrovskiy, who first discovered the steroid fossils 10 years ago.

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To survive asteroid impact, algae learned to hunt

To survive asteroid impact, algae learned to hunt
K/Pg, or Cretaceous-Paleogene extinction event, refers to the aftermath of the asteroid hitting Earth 66 million years ago. Credit: Odysseus Archontikis/University of Oxford

Tiny, seemingly harmless ocean plants survived the darkness of the asteroid strike that killed the dinosaurs by learning a ghoulish behavior—eating other living creatures.

Vast amounts of debris, soot, and aerosols shot into the atmosphere when an asteroid slammed into Earth 66 million years ago, plunging the planet into darkness, cooling the climate, and acidifying the oceans. Along with the dinosaurs on the land and giant reptiles in the ocean, the dominant species of marine algae were instantly wiped out—except for one rare type.

A team of scientists, including researchers at UC Riverside, wanted to understand how these algae managed to thrive while the mass extinction rippled throughout the rest of the global food chain.

“This event came closest to wiping out all multicellular life on this planet, at least in the ocean,” said UCR geologist and study co-author Andrew Ridgwell. “If you remove algae, which form the base of the food chain, everything else should die. We wanted to know how Earth’s oceans avoided that fate, and how our modern marine ecosystem re-evolved after such a catastrophe.”

To answer their questions, the team examined well-preserved fossils of the surviving algae and created detailed computer models to simulate the likely evolution of the algae’s feeding habits over time. Their findings are now published in the journal Science Advances.

According to Ridgwell, scientists were a bit lucky to find the nano-sized fossils in the first place. They were located in fast accumulating and high-clay-content sediments, which helped preserved them in the same way the La Brea tar pits provide a special environment to help preserve mammoths.

To survive asteroid impact, algae learned to hunt
High-resolution scanning electron microscope images of fossil cell coverings of nannoplankton highlighting holes that would have allowed flagella and haptonema to emerge from the cell and draw in food particles. Credit: Paul Brown/University College London

Most of the fossils had shields made of calcium carbonate, as well as holes in their shields. The holes indicate the presence of flagella—thin, tail-like structures that allow tiny organisms to swim.

“The only reason you need to move is to get your prey,” Ridgwell explained.

Modern relatives of the ancient algae also have chloroplasts, which enable them to use sunlight to make food from carbon dioxide and water. This ability to survive both by feeding on other organisms and through photosynthesis is called mixotrophy. Examples of the few land plants with this ability include Venus flytraps and sundews.

Plankton turn hunters to survive dinosaur-killing asteroid impact
Graphic explaining the research method and findings. Credit: Gibbs et al

Researchers found that once the post-asteroid darkness cleared, these mixotrophic algae expanded from coastal shelf areas into the open ocean where they became a dominant life form for the next million years, helping to quickly rebuild the food chain. It also helped that larger creatures who would normally feed on these algae were initially absent in the post-extinction oceans.

“The results illustrate both the extreme adaptability

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Death Of Sea Life Off Russia Peninsula ‘Caused By Algae’

Blooming algae was behind a recent mass death of sea animals that saw octopuses and seals wash up on the shore off a Russian peninsula, scientists said on Friday in the final conclusion to their probe.

Locals in Kamchatka, a volcanic peninsula in Russia’s Far East, raised the alarm in September after the animals were found dead and surfers complained of stinging eyes.

Scientists later said that up to 95 percent of marine life living along the seabed in the affected area had died.

Environmental campaigners said they were conducting their own inquiries and were not yet able to confirm the official probe’s findings.

Andrei Adrianov, vice president of Russia’s Academy of Sciences, announced the probe’s conclusions on Friday, saying the mass death was due to the effects of toxins from single-cell algae.

Speaking at the same meeting, Svetlana Radionova of environmental watchdog Rosprirodnadzor said her agency conducted over 5,000 tests.

She said the agency did not see a way the situation could have been caused by humans.

In a separate criminal probe, investigators announced they had eliminated oil spills and toxic waste as possible causes.

They added that the previously reported high levels of phenol and petroleum products were “not critical” and had been observed in the bay for decades.

Russia's branch of Greenpeace said they would not rule out any theories until they received the final results of their own probes Russia’s branch of Greenpeace said they would not rule out any theories until they received the final results of their own probes Photo: GREENPEACE / Handout

Environment Minister Dmitry Kobylkin said the situation in Kamchatka was improving.

But Russia’s branch of Greenpeace said they would not rule out any theories until they received the final results of their own probes.

Greenpeace’s Yelena Sakirko told AFP that human factors could have affected the algae — for example, if sewage or phosphates from washing powder and fertiliser leaked into the water.

Sakirko also said scientists were concerned that the incident could affect the food chains in the region, causing long-term damage to wildlife.

The World Wildlife Fund said its experts were likewise unable to make any conclusions yet.

“Unfortunately, public data available today does not fully prove any version of the ecological crisis off the coast of Kamchatka,” it said.

Russia has been hit by a string of environmental disasters this year.

Just weeks after the Kamchatka incident, an oil spill covering 35,000 square metres was reported in the waters of the port city of Nakhodka in Russia’s far east.

The most devastating incident took place in May, when some 20,000 tonnes of diesel leaked from a fuel tank into nearby rivers in the Siberian Arctic.

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Scientists harness satellites to track algae growth on Greenland ice sheet

Scientists harness satellites to track algae growth on Greenland ice sheet
Algae growing on the surface of the Greenland ice sheet darkens the surface, hastening summer melting. Here, researchers from Columbia University’s Lamont-Doherty Earth Observatory traverse a heavily affected area. Some of the dark material on the surface could also be dust or other debris. Credit: Kevin Krajick/Earth Institute

Scientists know that the brownish-gray algae that darken the Greenland ice sheet in summer cause the ice to melt faster, but only recently have they measured these blooms in the field, and only at few sites. To measure algal blooms across large regions and understand their effects on melting over time, they are now turning to space.

“Scientists go into the field and sample one or two spots where these blooms occur, but we don’t really know how they change over time or over a large region,” said Shujie Wang, lead author of a recent study showing that satellites can be used to track the growth of ice algae over wide areas.

To measure algae growth, Wang and her colleagues borrowed long-standing methodology used by other scientists to measure algae in the oceans, using satellite observations of water color. Marine algae differ from those on ice, but both kinds contain chlorophyll-a, which has a distinct reflected near-infrared radiation signature that satellite sensors can detect.

Mapping glacier algae over space and time can give researchers insights into how algae affect the reflectivity, or albedo, of the ice surface, said Wang, who conducted the research as a postdoctoral scholar at Columbia University’s Lamont-Doherty Earth Observatory. She is now an assistant professor of geography at Penn State University.

“Albedo is crucial for understanding how ice melts and what will happen in the future to the contribution of Greenland to sea level rise,” said Lamont-Doherty research professor Marco Tedesco, who supervised Wang’s work. “Little is known of the effects of algae on this, and the work by Shujie is pioneering in this regard.”

Light-colored snow and ice have a high albedo, meaning that they reflect most incoming solar radiation back to the atmosphere. But when algae accumulate, they darken the surface; this causes it to absorb more radiation, warming the ice and accelerating surface melt.

Scientists harness satellites to track algae growth on Greenland ice sheet
Study coauthor Marco Tedesco (right) measuring the reflectivity of the glacial surface. Such on-the-ground measurements are combined with satellite observations to study algae growth. Credit: Kevin Krajick/Earth Institute

The researchers used data from the Medium Resolution Imaging Spectrometer (MERIS) on the European Space Agency’s Envisat satellite to quantify algal blooms in southwestern Greenland from 2004 to 2011. They compared the data to measurements taken in the field and by NASA’s Moderate Resolution Imaging Spectrometer (MODIS), which measures surface albedo.

They found that chlorophyll-a signatures captured by MERIS matched field data, confirming that researchers can use ocean-color satellite data to measure algal growth and see how it changes over the summer. The same held true for the albedo changes measured by MODIS.

“We came up with a rough estimate that if algae growth doubles, then albedo decreases between 2 percent to 4

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