Research shows streams can be used as diagnostic tools for ecosystem health
When excess fertilizer from farms and cities runs off into water supplies, it can lead to severe human health and economic consequences. Utah County residents know this firsthand as they’ve witnessed Utah Lake become unusable the past two summers due to toxic algal blooms caused by this nutrient pollution.
But Utah Lake is just one example of the global issue; stunning satellite images show massive algal blooms in Lake Erie, the Baltic Sea, the Yellow Sea and across the planet. In fact, according to a recent publication in the top scientific journal Science, nutrient pollution is the second greatest environmental threat to humanity, with economic damages from the issue costing up to $2.3 trillion annually.
New research led by BYU ecosystem ecologist Ben Abbott presents a new tool to fight this global nutrient crisis. His study, recently published in Ecology Letters, found that rivers and streams could be used as “sensors” of ecosystem health, allowing both improved water quality and food production.
His research shows that sampling headwaters where streams form can identify which landscapes are resilient enough to handle the rigors of farming and which are vulnerable to leaching toxic residue into waterways.
“Currently, humans just go out and do agriculture wherever there is available ground,” Abbott said. “Using the fingerprint of water quality throughout the stream network, we can tell farmers or urban planners, ‘Hey, this land is really resilient, so you should do agriculture here.’”
Abbott and an international team of researchers used a data set from France that included samples from 60 small tributaries every two weeks over 12 years. In analyzing the data, they found nutrient concentrations went up and down over time, but the relative rank of each stream was stable across many years. This spatial stability of water quality means that periodic sampling of headwaters can reveal the location and strength of pollution sources.
Previously, ecologists theorized headwater streams were too variable to provide reliable data. The prevailing thought was any stream data collected on Thursday would change by Friday.
“We were surprised to see that the streams were good sensors of long-term nutrient conditions,” said study co-author, Jay Zarnetske, an environmental scientist at Michigan State University. “Our methods show that we can learn much from a relatively small number of samples if they are collected more strategically.”
Abbott and his colleagues are now testing their new method in the Bread Basket of the central U.S. and in Arctic and Boreal landscapes, where permafrost degradation is affecting river chemistry. They’re also organizing a citizen science project that will take place this spring to identify sources of nutrients to Utah Lake.
“If the patterns we found hold true, this method could be vital for human and ecosystem health in developing countries who don’t have resources to do major water studies,” Abbott said.
See the full study here: http://onlinelibrary.wiley.com/doi/10.1111/ele.12897/full