Notes

Seabird poop is a vital source of nitrogen and phosphorus
By Atlas Obscura, adapted by Newsela staff
02/01/2018
Word Count 688
Group of Empire penguin chicks in Antarctica. Penguins produce more poop than any other seabird. Photo by: Wolfgang Kaehler/LightRocket via Getty Images
Group of Empire penguin chicks in Antarctica. Penguins produce more poop than any other seabird. Photo by: Wolfgang Kaehler/LightRocket via Getty Images
Maybe you've noticed that a flock of seagulls sure can make a lot of poop. As it turns out, professionals who are interested in this sort of thing have noticed that, too.
In 1609, explorer Garcilaso del la Vega came across mounds of bird poop in Peru. He wrote they were so large that they looked like “the snowy crests of a range of mountains.” Incan farmers used the poop for fertilizer. This was a trick the Europeans eventually picked up on, too. Guano, a fancy name for seabird poop, played a pivotal role in the development of modern farming practices in the 1800s.
Ecologists around the world have documented the effects seabirds and their droppings can have on local plant communities.
However, until recently, no one had tried to measure the true scale of seabird poop and how it might affect different environments.
Studying Seabird Poop On A Global Level
A new paper was recently published in the science journal Nature Communications. Its authors dig into an important question. How much nitrogen and phosphorus from seabird poop is being added to global nutrient cycles? A nutrient cycle is the repeated pathway of an element through organisms and back into the environment. Nutrient cycles are an example of what scientists call biogeochemical cycles. The water cycle is another example.
Nitrogen and phosphorus are nutrients that are natural parts of every ecosystem, which is a community of living and nonliving beings. Nitrogen and phosphorus must exist within certain ranges in order to have balanced ecosystems. This means their movements and amounts are important to scientists.
Before this new study, scientists studied how seabird poop affected different regions. This latest article looks at seabird poop on a global level, says Miguel Angel Huerta-Diaz, a co-author of the study.
The team continued previous work that another research group carried out in 2012. That group developed an equation that enabled them to put in certain variables. Examples include seabirds' size, food preferences and time spent breeding.
Calculating Nitrogen And Phosphorus Numbers
This gave them an estimate of nitrogen being produced, so they tweaked the equation to work for phosphorus. They made sure to do the calculations with updated population numbers for seabirds.
“Our research was restricted to the breeding season, because that’s when they get together,” says Huerta-Diaz. Still, the team came up with some big numbers.
All seabirds combined produce approximately 99 billion grams of phosphorus per year and 591 billion grams of nitrogen.
About 13 percent of this phosphorus and 21 percent of this nitrogen is bioavailable. Bioavailable nutrients are those that become part of the nutrient cycle.
These numbers are small compared to other contributors. Examples include the phosphorus released by weathering rocks or the nitrogen from bean farming.
Transferring Nutrients From Ocean To Land
However, the numbers are similar to others that researchers tend to include when calculating global nutrient cycles. For example, seabirds transfer about as much nitrogen and phosphorus from the ocean to the land as commercial fishers do, Huerta-Diaz says.
Along the way, the team was also able to nail down some important details. At the species level, the poop king is the Macaroni penguin. They contribute nearly 20 percent of the total nitrogen and phosphorus pooped out by all seabirds.
King penguins aren’t far behind. Penguins as a whole have an outsized presence on the list of which seabirds poop the most. Heavy hitters that are not penguins include the Northern Fulmar, the Common Guillemot, the Short-Tailed Shearwater and the Thick-billed Murre.
Huerta-Diaz says this work is important. Seabirds are important sources of nitrogen and phosphorus. These are needed in the ecosystem. Nitrogen is important for growth and reproducing. Phosphorus is important for growth and repair of body cells and tissues.
He also thinks we should keep it in mind when thinking about how much we value seabirds, annoying as some, like seagulls, may be. “Seabirds are important sources of nitrogen and phosphorus,” he says.
As the study is still new, he continues, “we haven’t had time to digest everything.” When they do — as the seabirds have taught us — more conclusions will surely follow.