In a new paper appearing in Geophysical Research Letters and led by Q.B. Xu, a team of researchers looks at the history of deep ocean circulation by examining the Adélie penguins’ poop.

This story has me using a lot of language astronomy never prepared me to discuss.

As the science goes, researchers measured ocean circulation via poop samples collected from the Inexpressible Island on the Ross Sea. For 6,000 years, penguins have been pooping on this island, and as their defecation has built up, it has recorded the history of what the penguins have been eating, and thus recorded a history of the ocean waters in which the penguins feed.

In writing this story, I learned that the term for many years of accumulated bat or bird feces is guano and that research like this isn’t as possible as some researchers may like because there is a long history of folks collecting guano to use as fertilizer, but that is a different story.

On the Inexpressible Island in the icy Ross Sea, the penguin poo was plentiful, and researchers were able to collect thirteen different profiles of the penguins from different places on the island. In the layers of that six millennia of penguin processed ocean life, researchers were able to determine that periodically, changing ocean currents dredge minerals like cadmium from deep in the sea to the surface areas where penguins feed. This is a story of the chain of life.

Put simply, for 6,000 years, the ocean currents have periodically changed, and these changes affected how much of the deep sea cadmium reached the surface, where it is integrated into plankton, eaten by fish and krill, which is eaten by penguins who poop, and that poop is now being studied by researchers trying to understand ocean circulation.

Folks, I never thought that as a space scientist I’d ever be reporting a story like this one. This is further evidence that where there is a scientific question, there is a researcher willing to think super creatively to find an answer; heck, in this case, there was a research team willing to creatively dig through guano to get at some cool planetary science results, where our Earth is the planet in question.

More Information

AGU press release

“6,000-Year Reconstruction of Modified Circumpolar Deep Water Intrusion and Its Effects on Sea Ice and Penguin in the Ross Sea,” Q. B. Xu et al., 2021 July 26, Geophysical Research Letters