PARENT SESSION
Oral Session #23: Aquatic Ecology: Salt marshes, estuaries, ephemeral wetlands.
Presiding: D. Childers
Monday, August 5. 1:00 PM to 3:45 PM. Palo Verde Room, Radisson.

Comparison of microcrustacean community structure in ephemeral wetlands among the terrestrial ecoregions of Oklahoma.

Cosyleon, Gabriel^*,1, Schwartz, Steven¹, ¹ Oklahoma State University, Stillwater, OK

ABSTRACT- Although ephemeral ponds are ubiquitous and provide habitats for many unique invertebrates, our knowledge of community assemblage is weak. Patterns of species diversity can be attributed to the surrounding terrestrial environment, prevailing soil type biotic interactions and chance events of colonization. Many species exist as metapopulations in fragmented landscapes, and persist regionally by dispersal to nearby habitats. The use of naturally occurring metapopulations in patchy habitats as a model of fragmentation in a human dominated landscape can aid the understanding of their dynamics. Spatially isolated temporary wetlands, by definition, are separated from one another but are broadly distributed and occur in nearly all terrestrial habitats. An ecoregion approach aids in determining quantitative biological and regional chemical criteria, critical to protecting aquatic ecosystems. Oklahoma's heterogeneous landscape provides an excellent opportunity to assess the utility of terrestrial ecoregions in explaining and predicting the composition of microcrustacean fauna in ephemeral wetlands. We tested the hypothesis that established terrestrial ecoregions are adequate predictors of ephemeral pond community assemblage. We sampled 140 ephemeral ponds across the 11 terrestrial ecoregions of Oklahoma over a three-month period in 2001. This survey is the first of its kind for Oklahoma ephemeral wetlands and establishes a foundation for microcrustacean distributions. Using multivariate analyses, cyclopoid copepods, and some cladocerans were associated with, foliage cover, pH, conductivity and depth. With canonical correspondence analysis, separation among the 11 terrestrial ecoregions was significant (p<0.0075) based on species scores, indicating regional differences of species occurrences. Some species showed distinct correlations to specific ecoregions, such as Streptocephalus seali and Triops longicaudatus.

KEY WORDS: ephemeral wetlands, invertebrates, ecoregions, conservation