Florida’s ponds release more carbon than they store

New research shows that Florida’s 76,000 storm water ponds emit more carbon than they store. The research, carried out by scientists at the University of Florida, is published in the journal Communications Earth & Environment.  

“That finding means some ponds are doing us an ecosystem ‘disservice,’” said Mary Lusk, a UF/IFAS assistant professor of soil and water sciences. “Globally, we expect that as urbanization continues, there will be more and more of these small man-made ponds in urban landscapes.”

According to Lusk, the research will inform scientists’ attempts to estimate how much carbon is entering the atmosphere from these particular water sources on a regional basis.

“Then, once people start to understand that better, we hope they will take stormwater ponds into account for policies related to carbon control,” explained Lusk. “Stormwater ponds are everywhere in Florida. But they are understudied in terms of how they are impacting local ecosystems. Because they are man-made parts of the landscape, they sort of get overlooked, and people might assume they’re not very important ecologically.”

Lusk initially wanted to study nitrogen and phosphorus, common chemicals in artificial fertilizers, but her master’s student Audrey Goeckner convinced her to look at carbon in these ponds instead. 

“When I learned that I had the chance to work in stormwater ponds, similar to what I had grown up in around in my neighborhood, I immediately asked myself, well what about these little urban ponds? How do they compare to other aquatic ecosystems?” said Goeckner. “Turns out that despite their small size, they can rapidly store and process carbon, which adds up when you consider how many of them exist in developed landscapes and how many continue to be built.”

The scientists collected muck from the bottom of ponds from a canoe and measuring both the carbon stored in this “muck” and the carbon released. Interestingly, they found that not all ponds store carbon the same way and how much they store changes over time.  

“Our results suggest that when they’re new, they emit large proportions of carbon from the landscape and potentially increase storage over time,” said Lusk. “This means the older ponds are doing less of an ecosystem disservice to us than the younger ponds.”

“But if you think about the rate of new housing development in Florida, and how fast new stormwater ponds are being built in all that new development, it means we will always have a fresh new batch of young ponds that are just pumping carbon out to the atmosphere.”

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By Zach Fitzner, Earth.com Staff Writer