UW-Madison engineer examines the environmental impact of aquaponics in cold climates

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By Milthon Lujan

USA.- Earth’s climate is changing, and our global population is growing. What are the best ways to meet humanity’s nutritional needs, while also being mindful of the environmental impact of food production?

This kind of question fascinates Andrea Hicks, a professor of civil and environmental engineering at the University of Wisconsin-Madison. With research support from Wisconsin Sea Grant, Hicks is looking at the environmental impact of aquaponics—producing fish and plants together in a soilless, closed-loop system—in cold-weather climates like Wisconsin’s.

Said Hicks, “It’s a big question right now: how do we eat for climate change, to reduce our carbon footprint? And what’s the role of aquaponics in sustainable produce and protein production, especially when we compare it to other sources of protein like terrestrial animals?”

Scientists estimate that the food system is responsible for about one quarter of the greenhouse gases humans generate each year.

Hicks is tackling this timely issue in collaboration with Chris Hartleb, a professor of fisheries biology at the University of Wisconsin-Stevens Point and lead scientist for UW-SP’s Aquaponics Innovation Center, located in Montello. There, walleye and hybrid walleye are being grown, along with lettuce, bok choy and kale.

Her work takes a big-picture view that analyzes many inputs going into this type of food production: heat, electricity and fish feed. By performing what’s known as a life cycle assessment on the process as a whole, incorporating factors like air quality impacts, ozone depletion, greenhouse gas emissions and many others, she arrives at a carbon footprint for the processes at the Aquaponics Innovation Center.

While other researchers have studied the environmental impact of aquaponics, few (if any) have focused on cold-weather systems.

“Andrea Hicks’s approach was unique because previous life cycle assessments of aquaponics were conducted in tropical and subtropical environments that generally didn’t require a greenhouse and used tilapia—a tropical fish—as its fish type,” said Hartleb. In contast, the Aquaponics Innovation Center focuses on native, locally important food fish like walleye.

Together, Hicks and Hartleb are filling knowledge gaps that will be relevant for Wisconsin producers and those in states with similar climates.

“This is important information for those interested in Midwest aquaponics, since they will need to budget for higher heating and electrical costs,” said Hartleb.

This research also can help the industry diversify, which would bring greater economic stability. Explained Hartleb, “The driving force behind the research [at the Aquaponics Innovation Center] was to investigate the potential of raising walleye, locally-favored native fish, instead of tilapia, which is raised by nearly 90% of the U.S. aquaponic industry. Any industry so deeply rooted in one type of fish runs the risk of devastating consequences if that fish is affected by disease or short supply of fry.”

Being able to raise a greater variety of species in a greater variety of climates would benefit the industry as a whole.

Looking ahead, Hicks hopes to continue this research in collaboration with Hartleb. She intends to work with more aquaponics facilities across the state, and eventually plans to look at transportation impacts. Namely, how do the final destinations of the fish and plants impact the overall carbon footprint?

Said Hicks, “Let’s say you’re buying lettuce from a small producer in Wisconsin, and you’re in Minneapolis. How does that compare to if you bought mass-market lettuce grown in California or Arizona? That lettuce travels a long way and has that additional environmental impact [from transport]. If there’s a little more environmental impact [in the short-term] to growing it here, how does that compare in the long run?”

Hicks trusts that her research will help aquaponic producers make informed choices about how to operate in an energy-efficient manner.

She also aims to spread awareness among consumers about how aquaponics works and its prospects for the future. Hicks has become a bit of an enthusiast herself. “It’s a super-cool, closed-loop system when you think about the potential to save things like water, reduce agricultural runoff and the like.”

Source: University of Wisconsin Sea Grant Institute

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