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Zooplankton and Krill “Pee” Helps Determine Ocean Chemistry

Tiny marine life’s expelled ammonia fuels important chemical reactions

(Photo: Dr. David Phillips/Visuals Unlimited/Corbis)
smithsonian.com

Each evening, tiny marine organisms such as zooplankton and krill journey from the ocean's dark depths to the surface, where they feed under cover of darkness. Then, when the sun rises, they return to deeper, safer waters. That feeding ritual goes on, day after day, and—in sheer numbers—represents the planet's largest migration. 

Those tiny life forms' daily journey, it turns out, benefits not just their own bellies but the entire ocean ecosystem, Science Daily reports. As they move through the water column, they constantly expel ammonia—the same component found in urine. That ammonia, researchers discovered, fuels important chemical reactions in the ocean, especially in deeper, low-oxygen water.

To arrive at these findings, the scientists calculated the number of animals and the amount of ammonia they expelled at various depths in the oceans, Science Daily continues. Then, they determined how much of a contribution that organic waste would make for total chemical processes in the vicinity. 

While the researchers think that bacteria still lift the most weight when it comes to driving chemical reactions, ammonia deposited by krill, zooplankton and other tiny creatures, the team found, plays a significant role in ammonium's conversion to nitrogen gas, especially in oxygen-poor waters. "To me, it's exciting to think about the effects of animal behavior on a large scale in the ocean," author Daniele Bianchi said. "The effect of animals is enough to alter the rates of these reactions and maybe help explain some of the measurements."  

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