Relations of water quality, land use buffers, and diatom communities of connected depressions within the Cache River Watershed, Arkansas, USA

Over the past century, the Mississippi Alluvial Plain Ecoregion was altered from forest to agriculture. Associated with increased adjacent agriculture, water quality perturbations identified in Cache River connected depressions included elevated pH, DO, and conductivity. Non-metric Multidimensional Scaling indicated significant changes in the epidendric and benthic diatom communities in relation to conductivity and adjacent agriculture. The communities of less-impacted wetlands were dominated by species in the genera Eunotia, Gomphonema, and Pinnularia shifted towards communities dominated by Diadesmis contenta and Nitschia clausii in the more disturbed wetlands. Also, correlations among autecological metrics showed the relative abundance of planktonic diatoms increased and oligotrophic diatoms decreased with increased nutrient concentrations. This research demonstrates that assemblage condition is related to water quality perturbations and that water quality perturbations of connected depressions can be predicted using adjacent land use. Findings of this study support using diatoms and land use for developing indicators of wetland disturbance.