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Welcome to the home of the Sabo Laboratory at ASU!

Research in the Sabo lab focuses on links between hydrology and food web ecology in river and riparian ecosystems. We are particularly interested in understanding how water and energy link terrestrial and aquatic communities.  Continue reading

Example of an F1000 write-up

Article Title: Food-web dynamics in a large river discontinuum
Article Author/s: Wyatt F. Cross, Colden V. Baxter, Emma J. Rosi-Marshall, Robert O. Hall Jr., Theodore A. Kennedy, Kevin C. Donner, Holly A. Wellard Kelly, Sarah E. Z. Seegert, Kathrine E. Behn, Michael D. Yard.
Journal Title: Ecological Monographs
Journal Year: 2013
Journal Volume: 83(3):311-337
Much research has been devoted to describing the effects of streamflow regulation on food webs. However, only a few studies have thus far quantified how muting environmental variation may determine integrative ecological measures such as pathways of energy flow. Further, despite the great advances recently made by food web theory, there have still been very few attemps to test how theory may be able to predict food web stability in human-altered ecosystems such as regulated rivers. We liked this paper because it aimed at reconciliating food web theory and empirical research by studying a unique river discontinuum: the 386-km segment of the Colorado River that stretches between Glen Canyon Dam and Lake Mead (Arizona, USA).  Moreover, the paper presents a small textbook worth of valuable data and synthesizes many of the classic ideas in stream ecology in one place. The authors described food webs at six locations across a spatial gradient of perturbation (i.e., distance from Glen Canyon Dam), both before and after an experimental flood. They report a comprehensive set of longitudinal patterns in food-web structure, energy flow, and species interaction strengths, with altered food webs being generally simpler and more inefficient. However, perhaps the more compelling result is that, as theory predicts, food webs closest to the dam (i.e., those more altered) were clearly less resistant to flood perturbation than food webs downstream of tributaries. We believe this is an excellent empirical example of how dams, as large-scale modifications of river ecosystems, influence the way that energy enters and flows through food webs.

American bullfrogs & Robin’s summer

American bullfrogs are originally from the eastern United States, however, over the last century they have spread around the globe. They are a threat to many aquatic communities because they feed on and compete with native species, and they also spread amphibian diseases.

Our Masters student Robin Greene is interested in how these introduced amphibians influence aquatic ecosystems in arid-land rivers. Last summer she set up experiments on the bank of the San Pedro River (near Sierra Vista, AZ). The goal was to study how introduced bullfrog tadpoles, compared to native Woodhouse’s toad tadpoles, influence algae productivity, nutrient levels and microbial activity in the sediment.

Results to arrive soon… stay tuned!

Introduced bullfrogNative Woodhouse's toadExperimental set-up
[L to R: Bullfrog, Woodhouse's toad, Experimental setup]