Effects of Surface Water Decline on Streamside Animal Community Structure Using Stable Water Isotopes and a Water Web Approach

EPA Grant Number: F5F21954
Title: Effects of Surface Water Decline on Streamside Animal Community Structure Using Stable Water Isotopes and a Water Web Approach
Investigators: McCluney, Kevin E.
Institution: Arizona State University - Main Campus
EPA Project Officer: Just, Theodore J.
Project Period: September 1, 2005 through August 31, 2008
Project Amount: $111,344
RFA: STAR Graduate Fellowships (2005) RFA Text |  Recipients Lists
Research Category: Academic Fellowships


As human populations around the world grow, there are increasing demands on available water supplies, with many areas obtaining their water through groundwater pumping. Rates of groundwater pumping often exceed resupply rates, resulting in greater depth to groundwater and a reduction of surface water flows in local bodies of water. My research will address the impacts of these surface water reductions on the surrounding terrestrial animal community, along an arid stream in southeastern Arizona.


One major obstacle to studies of water use by animals is quantifying that use in the field. The extent of contribution of drinking versus trophic sources of water is of primary interest. I propose using differences in stable water isotopes ( 2H, 18O) to trace relative use of water sources across taxonomic groups, trophic levels, and gradients in surface water availability, identifying changes in a water web. These methods have not been adequately developed, but represent a potentially powerful research tool.

I will then use this water web to develop hypotheses about possible effects of surface water drying on terrestrial species assemblages. I will test these hypotheses in two ways. First I will conduct an experiment with a two by two design, in which I create enclosures that are either partially exposed to river water or are not exposed, and either contain predators, or contain only herbivores. This will allow identification of water-based interaction strengths between predators and herbivores. For the second component, I will create and maintain artificial pools of water in a drying portion of a stream, comparing overall community structure between pools and dry areas.

Expected Results:

Methods presented in this study will provide ecologists and conservation biologists with powerful tools to assess water-based relationships present in the terrestrial animal community. This assessment will allow better prediction of the effects of changes in water availability, including surface water declines. This study will also help to broaden the perspective of ecologists to consider water-based community interactions in future studies. Finally, this study will help to inform the public of potential impacts of ongoing reductions in groundwater and surface water. This knowledge could be potentially useful to a wide range of stakeholders, including conservation and hunting groups. This study could be applicable to large areas across the country and around the world, considering the large area of the earth covered by arid environments and that these regions are increasing.

Supplemental Keywords:

Water Web, Surface Water Decline, Drought, Terrestrial Animals, Community Ecology, Water Stress, Water Isotopes,, Scientific Discipline, Ecosystem Protection/Environmental Exposure & Risk, Habitat, Environmental Monitoring, Ecology and Ecosystems, animal responses, biodoversity, stable water isotopes, habitat disturbance, habitat loss, water web approach, surface water decline, terrestrial species, terrestrial habitat loss, conservation biology