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Research / Discovery

CSU Researchers Studying Effects of September Floods on Aquatic Ecosystems

March 12. 2014
Kortny Rolston

Some researchers might be disheartened if half of their monitoring equipment was wiped out by rain and flooding. Not LeRoy Poff, Chris Funk and Boris Kondratieff. The Colorado State University researchers view last September's historic flooding along Colorado's Front Range as an opportunity to understand if and how stream ecosystems, and the insects that live in them, can recover from such a massive disturbance and to test some of their hypotheses on biodiversity.

The team, along with a collaborator from Cornell University, recently received a $200,000 “rapid response” grant from the National Science Foundation to study the topic.

“It was an extremely unusual event and it’s a unique opportunity to understand how such large disturbances may fundamentally affect biological systems,” Poff said.

Before the storms

Poff and Funk, biology professors in the College of Natural Sciences, and Kondratieff, a bioagricultural sciences and pest management professor in the College of Agricultural Sciences, have been studying stream biodiversity in Colorado and Ecuador for the past few years.

Black Canyon Creek before the September 2013 floods.

They are evaluating how temperature, elevation, and hydrologic disturbances shape the genetic structure of insect populations and the food web structure of communities of insect species, with the goal of understanding the different ways temperate and tropical streams may be vulnerable to rapid climate change.

To do that, they set out monitoring equipment and sampled insects from 29 small stream sites across the Front Range in the Cache la Poudre, Big Thompson and St. Vrain river drainages.

They had collected data for several months before the 2013 storms hit.

Black Canyon Creek after the September 2013 floods.

“The storms were a big surprise, especially because they hit in September,” Poff said. 

Based on existing information, the team could form novel hypotheses about which species would be most impacted by a major disturbance, how the genetic structure of different species would change, which species might rebound, and even whether the food web of the streams would change and could recover.

Testing their hypotheses

With this new project, Poff, Funk, and Kondratieff will get to test those hypotheses.

“Because we had pre-disturbance data, we can now see if the hypotheses we formed were correct,” Poff said. “There is no way we could ever do a planned experiment to replicate the amount of water that flowed through all those streams in September.” 

The team expects the results and data to vary throughout the Front Range because not all drainages – or communities – got the same amount of rain. Streams around Boulder, for example, experienced far more flooding than those closer to Fort Collins, and more rain fell at mid-elevation than very high elevation.

In less severely disturbed systems, some insect species might have been able to find refuges under stable stones on the streambed, which means that those biological systems might recover faster than heavily flooded streams.

“Different levels of flooding affect human communities differently,” Poff said. “The same is true in biological communities.”

The team is particularly interested in knowing not only when and how biological systems in Colorado streams may recover but if those in the hardest hit areas even can.  That information would be valuable for those managing such systems – especially as climate change causes more severe weather to occur across the globe.

“What we want to know is if there is some threshold where these systems can’t recover and if so, what that threshold is,” Poff said.  “That is important information we need going forward.”