Spinning ocean eddies feed marine life with rich nutrients

Tiny organisms in the sea provide about half of Earth’s oxygen, which shows how much life below the waves matters for everyone on the planet. These organisms often cluster in drifting currents and eddies that seem small compared to ocean basins, yet each swirling system teems with energetic chemistry and unexpected activity.

Eddies in the ocean can measure around six to 62 miles wide, spinning off from busy coastal areas and then journeying into quieter open waters. Kevin Becker from GEOMAR led a project that explored these twisting flows and tracked what they deliver to regions far from shore.

Ocean eddies move nutrients offshore

Many people envision the ocean as calm on the surface and dark below. Scientists now know these waters are crisscrossed by powerful rotations that form near coastlines, including the Mauritanian upwelling system off West Africa.

These persistent eddies can carry material that supports marine life in places where conditions might otherwise be meager. They become natural transport lines for valuable molecules and nutrients that ocean creatures need.

Ocean eddies carry energy-rich lipids

In recent work aboard the METEOR M156 Expedition, researchers used high-resolution methods to identify nearly 1,000 different lipids from the top layers of the Atlantic.

These molecules make up a key fraction of phytoplankton bodies and provide energy for everything higher up the food chain.

“These eddies are basically the food trucks of the ocean,” explained Dr. Kevin Becker, lead author of the study. Those words hint at the diversity and abundance of molecules that swirl along with the current, ready to nourish anything that ingests them.

Surprising energy reserves

A fascinating discovery was the abundance of energy-packed fatty acids. They showed up in forms that creatures like fish and zooplankton cannot make on their own, which means these compounds help sustain life wherever the eddy spins.

Scientists uncovered storage lipids in certain spots within the rotating waters, pointing to thriving microscopic communities. This energy reservoir can be a jackpot for marine grazers that encounter it.

Eddies transport organic carbon

The team found that up to 9.7 ± 2.0 gigagrams (about 10,000 tons) of organic carbon may hitch a ride each year on westward-moving eddies.

These swirling blobs of seawater can journey hundreds of miles, distributing nutritious materials in areas that would otherwise see fewer life-sustaining resources.

Gaining a better handle on how much carbon these eddies export helps clarify the ocean’s big picture. It also helps scientists understand how changes in currents could affect wildlife far offshore.

Why this matters for fish and people

Marine organisms depend on carbon and nutrients to survive. Those lipids and fatty acids are building blocks for healthy fish stocks, which support local fisheries that put food on human tables.

Shifting ocean conditions under a warming climate could affect where and how these eddies form. That might change how nutrients flow across the sea, influencing the future of fisheries and coastal economies.

Community shifts and ocean health

The study showed that tiny phytoplankton play a starring role in shaping the chemistry within eddies. They thrive in upwelled waters before swirling along with the current.

Different species within these spinning waters can alter nutrient cycles in subtle ways. Researchers are examining how shifts in plankton communities ripple up to affect the entire food web and the global carbon balance.

Mauritania’s coastal waters are a prime example of how wind, currents, and topography blend to form these eddies. Similar processes occur elsewhere, hinting that these spinning parcels of water are a widespread phenomenon worth watching.

Scientists will collect more data from other upwelling zones to see if eddies in those places function in the same way. Far-reaching comparisons may reveal broader lessons about nutrient transport and carbon flow.

Climate may reshape ocean eddies

Mesoscale eddies may grow stronger or weaker as ocean temperatures change. Some climate models suggest patterns could shift in the coming years, yet the long-term consequences remain unclear.

More research is needed to figure out what will happen if these swirling waters become more or less common. Everything from the tiniest plankton to the largest fish might be affected.

The recent findings have shown that there is plenty to learn by exploring these spinning dynamics. Sophisticated techniques let experts pick apart complex chemical structures in water samples that were once a mystery.

“Our study highlights the central role of mesoscale eddies,” concluded Professor Dr. Anja Engel, lead scientist of the project and head of the Marine Biogeochemistry Research Division at GEOMAR.

The study is published in Communications Earth & Environment.

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