Spatial distributions of many freshwater invertebrates are associated with the concentration of total dissolved solids (TDS) in streams (usually measured as specific electrical conductivity – EC). These patterns are presumably caused by taxon-specific effects of TDS on the maintenance of ion and water balance, which is energetically expensive and thus could affect fitness. However, no studies have assessed if TDS-related effects on fitness metrics, such as growth and survival, are predictive of distributions......