Food Web Structure and Environmental Conditions in Ephemeral Wetlands

Summary

Our studies on ephemeral wetlands focus on fundamental and applied environmental regulation, especially of playa wetlands. Playas are common ephemeral wetlands in many arid to semi-arid regions of the world and especially common in the short-grass prairies of the U.S. Great Plains. They hold water for weeks to a couple of months yearly, but may go several years or much longer without filling. Large branchiopods (clam, fairy, and tadpole shrimps; see Fig. 1) are especially representative of these environments. From a fundamental perspective, we are interested primarily in ecological differences between ephemeral (especially playas) and permanent ecosystems, especially as they relate to the structure and regulation of food webs. This research employs stable isotope analysis of food webs and common sampling and species identification techniques (see Fig. 2). We focus on various questions, such as the following. What regulates trophic structure in ephemeral systems and how does that vary from controls in more permanent aquatic ecosystems? Do food web structure and its control vary from the beginning to the end of a playa’s hydroperiod? From an applied perspective, we are asking: (a) what are the best techniques for sampling playas; (b) can you predict biodiversity effectively from examining the egg bank of dry playas; and (c) how do anthropogenic forces (e.g., grazing and row crop agriculture) modify natural regulation of trophic structure in playas? 

Answers to these questions are integral in not only understanding how ephemeral systems work, but to create a general theory of what controls trophic structure.  Our research aims to bridge across system permanence and create a framework describing what drives trophic structure, how it is controlled, and how it is modified with human interaction.  These projects are currently supported by EPA grants from Regions 7 (Kansas City) and 8 (Denver).

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