Crayfish densities in relation to concentrations of metals in sediment and water in Madison County, Missouri, 2004-2015

Data was collected during a series of studies that assessed the effects of metals on crayfish in mining districts in Missouri. Adult crayfish were collected in riffles to determine whether crayfish densities were lower at sites downstream of mining areas compared to sites upstream of mining areas. Metal concentrations in surface or pore water and less than 2-mm sediment were measured and incorporated into toxic units and sediment probable effects quotients.