Meta-ecosystems: Waterfowl mediated movement of materials and organisms in prairie pothole wetlands

Background/Question/Methods    The meta-ecosystem concept is an attempt to combine metacommunity, ecosystem and landscape ecology. In meta-ecosystems, both organismal dispersal and material movement between patches can have important effects on communities, and a realistic framework of natural systems requires that we consider both processes jointly.     We present a case-study of natural meta-ecosystems by studying the role of waterfowl in structuring zooplankton communities in prairie pothole wetlands.  Zooplankton are numerically dominant, conspicuous members of the wetland metacommunity which rely on passive dispersal by wind, rain or some animal vector.  Waterfowl, our target dispersal vector, are conspicuous, behaviorally adaptable, highly mobile and economically important members of wetland habitats.  They are thought to have possible effects on zooplankton either by dispersing zooplankton propagules among ponds or by moving nutrients into (via defecation) or out of (via consumption of macrophytes and invertebrates) ponds.     We use wetland surveys of the Prairie Coteau and mesocosm experiments to show how dispersal of materials and organisms by waterfowl can affect zooplankton abundance and community composition.  In our mesocosm experiments, we manipulated dispersal level of waterfowl excreta and zooplankton to determine how dispersal of materials and organisms can influence the zooplankton community.

Results/Conclusions    We show evidence that waterfowl disperse a limited subset of locally rare zooplankton species between wetlands, and we provide evidence that these dispersed species have important effects on the community assembly process within wetlands.  In mesocosm experiments, we also show that waterfowl fecal inputs promote and maintain zooplankton diversity, though individual species show idiosyncratic responses.  Our research shows that although waterfowl may have short residence times within wetland patches, they can have impacts on invertebrate communities within the wetland complex by moving organisms and materials between wetlands.  Thus, waterfowl are an important contributor to community and ecosystem processes in the wetland complex.