A new way to trace the origins of algae could identify water sources

Avondale, Pa., May 20, 2025 (GLOBE NEWSWIRE) — New research from scientists at the Stroud™ Water Research Center shows how real-time chlorophyll sensors can be used to determine the origins of algae in rivers and streams , and in turn, identify the sources of pollution that algae sometimes signal.

The study, led by scientists Marc Peipoch, Ph.D., and Scott Ensign, Ph.D., is the first to test and support the use of existing sensor technology to analyze chlorophyll concentration and its movement over time to infer then algae originates in a freshwater environment.

Existing methods for measuring algae via chlorophyll concentration in waterways are simple and commonly used to indicate possible water pollution. But where and when does algae come from remains a mystery. An increase in chlorophyll concentration could simply be the result of a strong storm flow carrying algae from the river bed and into the water column. More worryingly, it could indicate nutrients from farms, a leaking septic tank, or a sewage treatment plant leaking into fresh water and stimulating faster algae growth.

The researchers decided to test the use of EnviroDIY™ monitoring stations, a combination of sensors and Mayfly data loggers, to collect water quality data every few minutes during storms, when algae would move, mix, and flow faster in Brandywine Creek, a tributary of the Christina River in Pennsylvania.

Their theory was that if algae were abundant near the point of detection (in this case, the sensors), the chlorophyll concentration would change faster during storms than if the algae came from further away.

“Whether the chlorophyll concentration initially increases or decreases can indicate whether the algae was growing attached to the streambed or floating in the water above,” Peipoch says.

The data confirmed what the scientists had suspected and their findings were published in the peer-reviewed journal Limnology and oceanography letters.

Although not all algae is harmful, too much of any variety can be deadly. When algal blooms eventually die, they feed bacteria that starve the water of oxygen, leading to the death of fish and the death of other aquatic life. Algae outbreaks can also sicken humans, their pets, and marine animals.

Warming temperatures from climate change, excess sunlight from deforestation, and fertilizers from agricultural runoff can fuel algae growth.

Ensign says, “This is an exciting discovery. We have demonstrated for the first time a method to identify sources of algae using existing sensor technology. We believe this method should be applicable at a variety of scales – from the small, shallow streams we see in our backyards to rivers as powerful as the Mississippi.

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About the Stroud Water Research Center

The Stroud Water Research Center seeks to advance knowledge and management of freshwater systems through research, education, and watershed restoration globally and to help businesses, landowners, policy makers and individuals to make informed decisions that affect the quality and availability of water around the world. The Stroud Center is an independent 501(c)(3) nonprofit organization recognized as a world leader in freshwater science, environmental education, and watershed restoration, with a site high school studying tropical ecosystems in Costa Rica.

www.stroudcenter.org