Linkages between Land Use, Invasive Fishes, and Prairie Pothole Wetland Condition

Abstract

In the North American Prairie Pothole Region (PPR), agricultural and developed land uses may affect wetland condition by influencing contaminant inputs and invasions by fishes. To improve understanding of human impacts on wetlands, we quantified relationships between land use, physical attributes (herbicides, chloride, turbidity, wetland size), and biological attributes (tiger salamander [Ambystoma tigrinum] abundance; fish, plant, and invertebrate assemblages) of 45 permanently-ponded Iowa wetlands. Wetland area and water-column chloride concentration increased as cropped and developed land-covers increased in the watershed. However, we did not find strong relationships between land-cover type and biological attributes, with the exception of plant cover, which declined as water-column herbicide concentration increased. Fish abundance was an especially important determinant of wetland condition. As fish abundance increased, turbidity increased, and plant cover declined. Tiger salamander abundance and macroinvertebrate taxon richness also declined as fish abundance increased. Our findings suggest that in Iowa PPR wetlands, chloride concentration is an indicator of land-use intensity, and plant abundance can be predicted to some extent by herbicide concentrations. However, wetlands with low macroinvertebrate diversity, plant abundance, and salamander abundance tend to be those with high fish abundance.