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Ancient Ocean Chemistry Maintained Oxygen Levels for Complex Life
Confirmed
In Short: Researchers have uncovered a self-sustaining cycle in ancient ocean chemistry that helped maintain high oxygen levels after the Great Oxidation Event, approximately 2.3 billion years ago, according to a study published in Scientific Frontline.
The cycle, which depended on phosphorus recycling, fueled biological productivity and helped sustain atmospheric oxygen levels.
As oxygen entered Earth's oceans, sulfate concentrations also increased, creating conditions that supported life-friendly environments.
Understanding these biogeochemical cycles aids in predicting the consequences of modern ocean deoxygenation due to climate change and refines models used to identify habitable, ocean-bearing exoplanets.
Hydrothermal vents on the ocean floor, similar to hot springs on land, fuel entire ecosystems that survive on chemical energy instead of sunlight.
These vents, found mostly along mid-ocean ridges where tectonic plates spread apart, gush fluids heated by magma to 400°C (750°F), supporting unique ecosystems.
In the unexplored expanses deep below the ocean waves, life finds many ways to thrive, sometimes evolving to metabolize volcanic chemistry instead of sunlight.
For instance, researchers piloting a remotely operated vehicle spotted several amphipods, tiny crustaceans recorded throughout the world's deep oceans, clinging to giant sea spiders.
These findings highlight the resilience and adaptability of life in extreme environments, providing insights into how life might exist on other planets.
The method of phosphorus recycling could help create plastic products with the best of both worlds by combining durability with an eco-friendly life cycle.
What this adds
The study provides new insights into how ancient ocean chemistry supported life-friendly conditions, but the exact mechanisms of phosphorus recycling remain under investigation.
The research also underscores the importance of understanding biogeochemical cycles in predicting the impacts of modern climate change on ocean ecosystems.
What's confirmed
- They found that changes in ancient ocean chemistry created a self-sustaining cycle that helped keep oxygen levels high after they first rose.
- The researchers found that as oxygen entered Earth's oceans, sulfate concentrations also increased.
- Today, climate change is causing parts of the ocean to lose oxygen.
- "Earth's history shows that oxygen, nutrients, and life evolved together," Bekker said.
- Scientists have helped solve a longstanding mystery about how Earth remained habitable after oxygen first accumulated in its atmosphere more than two billion years ago, providing evidence that ancient ocean chemistry sustained life-friendly conditions.
- The cycle depended on phosphorus recycling, which fueled biological productivity and helped maintain oxygen in the atmosphere.
- Less clear was how oxygen levels then remained high enough over millions of years to support increasingly complex forms of life.
What's still developing
- Origin/History : The process began following the Great Oxidation Event, around 2.3 billion years ago, supporting the persistence of life-friendly conditions.
- Trilobites Image Credit: Scientific Frontline / stock image Scientific Frontline: Extended "At a Glance" Summary : Ancient Ocean Chemistry and Habitability The Core Concept : A self-sustaining cycle of phosphorus recycling in ancient oceans that maintained high atmospheric oxygen levels after the Great Oxidation Event, approximately 2.3 billion years ago.
- More life meant more organic carbon was buried, allowing additional oxygen to accumulate in the atmosphere and reinforcing the cycle.
- Until now, scientists could measure only the total amount of phosphorus preserved in rocks, making it difficult to determine how much had actually been available to support life in ancient oceans.
- The animal communities found at individual vent fields can form unique ecosystems found nowhere else in the ocean.
- Around them thrives one of Earth’s strangest ecosystems—tubeworms, shrimp, and microbes that live on chemistry instead of sunlight, powered by the planet’s inner heat.
- In 1977, scientists exploring an oceanic spreading ridge near the Galápagos Islands made a stunning discovery: openings in the Pacific Ocean seafloor with warm, chemical-rich fluids flowing out.
- But if it really does roam the world's oceans, Pérez-Schultheiss and colleagues may have found at least one creative solution to their transportation problem.
- Thousands of meters below the Southeast Pacific Ocean, scientists have documented just such a partnership.
- It isn't very good at swimming, and doesn't have a planktonic larval stage that helps carry it far and wide on ocean currents.
- Yet it still gets around – recorded across the Pacific, Atlantic, Indian, and Southern oceans, at depths ranging from around 690 to 3,500 meters (2,264 to 11,483 feet).
- “Before now, people might have avoided using these materials, despite their strength, durability and lightness, because they didn’t have a good way to recycle them,” said Zak Page, a UT associate professor of chemistry and corresponding author on the paper.