Graduate Students / Postdoctoral Researchers
Beth Hagen (Ph.D. candidate)
I am interested in resource subsidies between river and riparian ecosystems. Specifically, the role emerging aquatic insects play for foraging bats. Many bat species forage heavily along waterways, consequently emerging aquatic insects may make up a significant portion of their diets. However, few studies have focused on the important ecological role bats play as consumers of aquatic insects, thus linking the river and riparian food webs. Bats make up nearly 25% of all mammal species and serve important ecological roles in pollinating flowers and controlling insect populations. Despite their significance more than half of the bats species in the United States have severely declining populations or are listed as federally endangered.
My research is located within the San Pedro River, which flows north from Sonora, Mexico into southeastern Arizona and is one of the last entirely free flowing and perennial rivers in the desert southwest. The San Pedro River valley is an ideal location for this study due to the high bat diversity representing more than half of the species of bats found in the United States and Canada. The San Pedro River valley supports 24 species of bats including the lesser long-nosed bat, a federally endangered species; and the Mexican long-tongued bat, a species of special concern.
By assessing resource subsidies across river-riparian ecosystems, I will be able to expand our current understanding of aquatic and terrestrial food webs to larger landscape scales. I am asking questions related to various temporal and spatial scales. For example, how might seasonality influence the flux of resources between aquatic and terrestrial food webs? Will this relationship diminish with increased distance from the stream? How might riparian vegetation, land use, and climate affect this relationship?
Andy Keller (MS candidate)
My research background is the environmental sciences with an emphasis in conservation biology. As an undergraduate, I conducted research to determine the effects of multiple cattle grazing regimes on the productivity and diversity of Arizona rangelands. Specifically I was interested in the response of arthropod communities on varying levels of ungulate disturbance. Along with this research a collaboration of different organizations was created, linking scientists, government, and cattle ranchers in order to reach common goals in terms of rangeland management. The culmination of this research resulted in the ongoing collaboration between specific interest groups and a continued monitoring program of grazing on the Colorado Plateau.
As a graduate student I am interested in riparian zones in arid regions and how native and non-native frog species interact in these habitats. Specifically my focus is on invasive bullfrog populations and their influence on native frogs such as the Chiracahua Leopard Frog. I hope to define critical habitat for imperiled frog species, which can be used in future reintroduction programs of amphibian species.
My interests also involve modeling of endangered or threatened marine mammal populations in order to assess the status of these stocks according to the Endangered Species Act. My experience in this field includes a PVA analysis of the eastern North Pacific gray whale and the Bowhead whale stock in the Bering Sea as means of determining listing status under the ESA for these stocks. I have also spent time in the Gulf of California studying the California Sea Lion in order to define behavior parameters that may affect dispersal and abundance of this species. This data will be used to set modeling parameters in order to provide more accurate projections of growth rates and dispersal of sea lions.
Kevin McCluney (Ph.D candidate)
My dissertation research focuses on the impacts of water limitation on terrestrial animal community structure. Specifically I am interested in how scarce and variable water sources alter terrestrial animal community structure along the San Pedro River in Southeastern Arizona. I am currently working on methods of using stable water isotopes to characterize the flux of water through the terrestrial animal community and the ecosystem, or, identifying a "water web" (instead of a food web).
Other academic interests include conservation biology, fire ecology, and ecologically sustainable management. I am currently the ecology and evolution graduate representative for the School of Life Sciences and lead a weekly ecology and evolution reading group.
Non-academic interests include organic vegetarian cooking, fencing, wild parties, and long walks on the beach (oh wait, I'm in Arizona, let's make it long hikes in the mountains and buttes).
Publications:
James, F. C., P. M. Richards, C. A. Hess, K. E. McCluney, E. L. Walters, and M. S. Schrader. 2003. Sustainable forestry for the red-cockaded woodpecker's ecosystem. In: R. Costa and S. J. Daniels, editors. Red-cockaded woodpecker: road to recovery. Hancock House Publishers, Blaine, Washington.
Candan Soykan [pronounced John-don] (Ph.D candidate)
I'm a Ph.D. student with broad interests in community ecology, conservation, and public policy. I entered graduate school because of my love of nature and wildlife, and my desire to use science as a tool to advance conservation efforts. My dissertation research focuses on the food web along the upper San Pedro River in southeastern Arizona. In particular, I am interested in the effects of spatio-temporal variation in resource availability on species interactions and community structure. I work primarily with arthropods, small mammals, and omnivores (skunks, foxes, etc.), doing such things as pitfall and live-trapping, radio-telemetry, scat collection and analysis, and scent station monitoring. I also have two side projects: One involves recording temperature, humidity, and wind speed/direction in different habitats types along a gradient from the river's edge to the desert scrub (during different times of the year); the other involves mathematical modeling of indirect interactions between species in temporally-variable environments. My overall goal is to advance our understanding of species interactions in complex, natural settings.
In addition to my research, I am involved with the Graduates in Earth, Life, and Social Sciences, an interdisciplinary group of graduate students at ASU that organizes an annual research symposium (http://www.asu.edu/clubs/gelss/). I also enjoy exercising, cooking, and long, moonlit walks on the beach...
Publications:
Fagan, W.F., M.-J. Fortin, and C. Soykan. 2003. Integrating Edge Detection and Dynamic Modeling in Quantitative Analyses of Ecological Boundaries. BioScience 53(8): 730-738.
Sabo, J.L., R. Sponseller, M. Dixon, K. Gade, T. Harms, J. Heffernan, A. Jani, G. Katz, C. Soykan, J. Watts, J. Welter. in press. Riparian habitats increase regional, but not local species richness. Ecology.
Theodore Kennedy (Postdoctoral Researcher)
The overall goal of my research is to link applied and basic research in aquatic ecology to understand the consequences of human impacts on aquatic ecosystems. My dissertation research focused on the consequences of saltcedar (Tamarix ramosissima) invasion along a desert stream (Jackrabbit Spring). I found that saltcedar heavily shaded Jackrabbit Spring and shifted the dominant organic matter inputs from high quality autochthonous production to low quality allochthonous saltcedar leaf litter. Stable isotope analysis revealed that this change in organic inputs promoted the persistence of exotic aquatic consumers and negatively impacted endangered pupfish, likely via reductions in the algal-based food on which it is dependent. As a member of Dr. John Sabo’s lab, I am currently investigating the controls of food chain length (i.e. the number of trophic levels) in stream/river ecosystems.
Publications:
Kennedy, T.A. and S.E. Hobbie. 2004. Salt cedar invasion (Tamarix ramosissima) alters organic matter dynamics in a desert stream. Freshwater Biology 49: 65-76.
Kennedy, T. A., S. Naeem, K.M. Howe, J.M.H. Knops, D. Tilman, P. Reich. 2002. Biodiversity as a barrier to ecological invasion. Nature 417: 636-638.
Levine, J., T.A. Kennedy, S. Naeem. 2002. Neighbourhood-scale effects of species diversity on biological invasions and their relation to community patterns. Pages 114-124 in Biodiversity and ecosystem functioning: syntheses and perspectives. Eds. Naeem, S., M. Loreau, P. Inchausti. Oxford University Press.
Raeffaeli, D., T.A. Kennedy, and 8 others. 2002. Multi-trophic dynamics and ecosystem processes. Pages 147-154 in Biodiversity and ecosystem functioning: syntheses and perspectives. Eds. Naeem, S., M. Loreau, P. Inchausti. Oxford University Press.
Naeem, S., J. M. H. Knops, D. Tilman, K. M. Howe, T. Kennedy, and S. Gale. 2000. Plant diversity increases resistance to invasion in the absence of covarying extrinsic factors. Oikos 91: 97-108.
Kennedy, T. A. 1998. Patterns of an invasion by Argentine ants (Linepithema humile) in a riparian corridor and its effects on ant diversity. American Midland Naturalist 140: 343-350.
Mike Booth (Research Technician)
I am fascinated, aesthetically and intellectually, with freshwater aquatic communities. I see these communities as highly threatened systems that are critical to the health of the overall community and want to contribute to a more complete understanding of their functioning and conservation. I am particularly interested in examining the community interactions of fish, herpetofauna, and aquatic invertebrates, as well as developing applied management solutions for systems in danger of permanent and irreversible damage. My overall goal is to integrate multiple levels of ecology by examining the impact that community interactions have on population or ecosystem level processes. I believe that in-depth natural history knowledge of a system is key to developing accurate (or at least biologically realistic) models of their inter- and intra-community interactions. I am currently working on John Sabo's food chain length project -- as such, I am known as the "travelling man", as I spend a large portion of every month in the field, working throughout the southwest. When I am not working (and sometimes when I am), you will find me shooting photos, rock climbing, or riding one of my bicycles.
Undergraduate students
Will Patterson (SOLUR student in Barrett Honors College)
Collaborators
Jacques Finlay (University of Minnesota)
David Post (Yale University)
Leah Gerber (Arizona State University)