Northern Prairie Wildlife Research Center
Agricultural practices may also have less obvious impacts on invertebrate communities in wetlands. Wetland drainage in the PPR has been focused primarily on shallow temporary and seasonal wetlands within agricultural fields. This increases the distance between wetlands, thereby increasing the distances aquatic invertebrates must travel to repopulate wetlands. Hence, repopulation following natural drought cycles may be prevented or delayed (Euliss et al. 1999). Dispersal by wind (Pennak 1989), in the digestive tracts of birds (Proctor 1964, Proctor et al. 1967, Swanson 1984), and by clinging to vertebrate and invertebrate fauna (Segersträle 1954, Rosine 1956, Fryer 1974, Peck 1975, Swanson 1984) may also be diminished if the distance between remaining wetlands is increased.
Temporary wetlands dry quickly during most years, and most farming operations cultivate their basins and adjacent upland areas. Kantrud and Newton (1996) found lower plant species diversity and greater percentages of unvegetated bottom in the wet meadow zones of agricultural wetlands, and Kantrud and Stewart (1977, 1984) found poor bird use of tilled prairie wetlands. Our results suggest that agricultural practices have limited invertebrate communities as well. Of all the wetland classes in the PPR, temporary wetlands are most directly influenced by farm operations; hence, their condition may provide a general indication of wetland health within an area. In much the same fashion as "indicator species" in biological assemblages, temporary wetlands may alert managers of potential problems in an area that may include more permanent wetland classes. Future work should address the relationship between the condition of temporary wetlands and the condition of other habitats in an area, including more permanent wetlands.
Our study demonstrates that aquatic invertebrate communities of temporary wetlands in the PPR have been altered by agriculture. Future studies are needed to clarify causal mechanisms and the ecological implications on other wetland-dependent communities, such as waterfowl that utilize these wetlands to satisfy nutritional requirements (Swanson et al. 1977). We suggest that future studies be initiated collaboratively with agricultural interests to facilitate development of interdisciplinary approaches that promote land management practices beneficial to both wildlife and agricultural interests (Gleason and Euliss 1998).