Follow the flow: National cohort explores low-water impacts on aquatic environments

In August 2023, a group of postdoctoral researchers gathered in Santa Barbara, California. They came from different backgrounds and represented disparate regions, but they shared a common focus: our Nation’s aquatic ecosystems. Among them, Megan Behnke brought her expertise as a biogeochemist studying the flow of nutrients through Alaska’s cryosphere-influenced watersheds.

Originally from Juneau, Behnke worked as a stream chemistry technician at the University of Alaska Southeast’s Alaska Coastal Rainforest Center in 2016. After receiving her PhD in Chemical Oceanography from Florida State University in 2022, Behnke returned as a postdoctoral researcher to continue her work tracking particulate organic carbon in aquatic environments in the Northeast Pacific Coastal Temperate Rainforest. 

In Santa Barbara, Behnke represented the Alaska Climate Adaptation Science Center as one of nine fellows in the Climate Adaptation Postdoctoral Future of Aquatic Flows cohort. The cohort was assembled from 2022 to 2024 to use a collaborative research approach to explore how climate change contributes to changes in aquatic flows across the nation. The cohort received training and mentorship in the methodology, opportunities, and challenges of “team science,” as this interdisciplinary approach has been coined.

Now, Behnke reflects on the unique experience of working with a cohort of postdoctoral researchers with varied expertise to synthesize knowledge on aquatic flows. The group included atmospheric and climate modelers, hydrologists, estuary specialists, precipitation and weather specialists, and biogeochemists.

“I think we all learned a lot about speaking across disciplinary boundaries and gained new appreciation for each other’s fields and how each field brings critical perspective to tackle these big, complex issues,” said Behnke.

The cohort came together to address a topic with national relevance for aquatic systems: low-flow events, or periods of limited water, in aquatic ecosystems. They recently published their findings from an interdisciplinary investigation of low-flows’ impact on water quality and management approaches in Frontiers in Earth Science.

When water flow reaches extreme lows, the repercussions can be profound. Low-flow periods create warmer, saltier streams, with less dissolved oxygen. Water clarity and nutrients fluctuate unpredictably. When streams dry up, aquatic species lose critical habitat connectivity, sometimes becoming trapped in increasingly polluted, shrinking water bodies. Across the US, the impacts and capacity to address these events are not uniform. The West and Southeast regions are facing the worst effects, with increasingly frequent and drier low flows when compared to less frequent and wetter low flows in the Central Plains, Midwest, and Northeast.

While climate-driven shifts in temperature and rainfall patterns impact the timing and frequency of these events, rising water demand, urban sprawl, and deforestation also influence the severity and impact of low-flow periods. The result is a decline in aquatic health and a decrease in primary productivity. 

In Alaska and the Pacific Islands, a scarcity of data about water quality response to low flows has restricted action towards managing these stream-drying occurrences. 

“There has been really good work done in the state around low flow impacts on salmon, but Alaska covers such an incredibly large area (and large percent of the land area of the US), and field logistics (particularly in the winter) are so challenging that of course there are major data gaps. Continuing to work on year-round aquatic sampling campaigns throughout the state will be important for further constraining future low-flow impacts,” said Behnke.

Addressing water quality concerns requires a local, interdisciplinary approach. The cohort stressed that their findings are not “one size fits all,” highlighting the need for localized data and tailored approaches. But there is also opportunity to compare river management challenges and solutions across hydrologically similar regions.

For Behnke, this experience in team science highlighted the challenges and benefits of working across disciplines. With such a varied group of researchers, the need for clear and precise communication was paramount, as each discipline worked with its own set of definitions.

Following the completion of the Aquatic Flows fellowship in 2024, Behnke joined the University of Alaska Southeast as a Professor of Chemistry. She continues her research on the shifting flow of nutrients through cryosphere-influenced watersheds.