“They’re just waddling around in their poop.” Penguin poop is melting snow in Antarctica. Here’s how | Discover Wildlife

Colour-changing snow algae is a common and increasingly widespread sight along the coastline of the Antarctic Peninsula, its growth accelerated by rising temperatures across the continent. It’s also speeding up snowmelt – and, according to new research, penguin poop plays a big role in the process.

The research into this phenomenon was conducted by scientists from the University of Colorado Boulder, USA, with the findings published in the Journal of Geophysical Research: Biogeosciences.

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Antarctic snow algae changes colour depending on the amount of nutrients it’s receiving. When nutrients are abundant, the algae can stay active, packing their cells with green pigments such as chlorophyll to ramp up photosynthesis and grow as much as possible during the short Antarctic summer. When nutrients are scarce, the algae hunkers down – producing sunscreen-like red pigments to protect itself from the sun.

In some areas, snow algae grow densely enough to make the snow itself take on their hue. Red snow absorbs about 20 per cent more energy from sunlight than clean, white snow, while green snow absorbs twice the amount – 40 per cent more than clean snow. This darkening of the surface leads to more warming and snowmelt.

Snow algae often bloom in close proximity to penguin colonies – and for good reason. When penguins traipse their poo across the snow, they’re inadvertently supplying the algae with vital nutrients, which keep the blooms green.

“The link between wildlife, nutrients and snow algae is a critical missing component in projections of expansion of ice-free areas in Antarctica,” said Alia Khna, a cryosphere biogeochemist at the University of Colorado Boulder and senior author of the study.

“Without accounting for these biological darkening effects, we are likely underestimating how rapidly coastal snowpacks are melting and how fast ice-free terrain will expand across Antarctica.”

Stinky samples

The researchers travelled by boat across the rough seas of Drake Passage, gathering samples of both red and green snow algae along the coast of the West Antarctic Peninsula. They covered five degrees of latitude and areas with and without penguin colonies.

“[Penguin] poop can visually look similar to the red snow algae,” said Khan. “It’s very stinky working near penguins. They’re just waddling around in their poop and tracking it all over the snow.”

At the lab, the researchers counted the number of algae cells in each snow sample under a microscope and extracted the pigments and nutrients. This determined that where algae cells had predominantly green pigments, the snow had far more phosphate – a critical nutrient found in penguin poop.

“This finding links the marine food web to snow ecology. The penguin guano [poop] acts as a fertiliser… that fuels these dense green snow algae blooms,” said Khan.

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Feedback loop

As penguins make their way closer to the south pole in response to changing conditions, the potential for fertilised snow algae habitats to expand grows – and the melt-enhancing effects of the algae spread along with these habitats.

According to the scientists, current projections of Antarctic melting don’t yet account for this phenomenon, with Khan’s team being the first to show the link between penguin poop and the different coloured stages of snow algae’s life cycle. More research is needed before it can be considered in snowmelt projections for the Antarctic Peninsula.

Read the full findings here.

Top image: A colony of gentoo penguins on Half Moon Island, Antarctica. Credit: kertu_ee/Getty Images