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Field and laboratory data to determine lethal pesticide concentrations for control of invasive crayfish

December 1, 2021

Data were collected associated with the application of a pesticide to a stormwater retention pond and burrows to suppress or eradicate an invasive crayfish species, Procambarus clarkii, in support of high-priority research developing control methods to mitigate impacts of invasive crayfish within the Great Lakes Basin. Effectiveness of the treatment was accessed using an in-situ bioassay and by measuring pesticide concentrations in water, sediment, and caged crayfish. Water quality data, including temperature, pH, specific conductance, dissolved oxygen, alkalinity, hardness, ammonia, and turbidity, in stormwater ponds was collected to evaluate whether environmental conditions may impact treatment effectiveness and persistence of pesticide. Pesticide concentrations were assessed prior to chemical application of ponds and monitored for 88 days post application. Pesticide concentrations in burrows and adjacent pond were monitored prior to treating burrows and for up to three days post application. Research will assist management and regulatory agencies in interpretating laboratory acute and chronic data relative to field-based treatment and effects data, and in developing permitting requirements and best management practices for open-water and burrowed invasive crayfish populations. Data associated with laboratory studies were collected to determine 24-hr acute lethal concentrations of two pesticides containing pyrethrin or cypermethrin for two crayfish species, Procambarus clarkii and Faxonius virilis. Tests investigated whether two nominal temperatures (10 and 22 ?C) and total suspended solid affected pesticide toxicity. Water quality monitoring during testing followed standard testing protocols and included temperature, pH, specific conductance, dissolved oxygen, alkalinity, hardness, ammonia, turbidity, and total suspended solids in test jars with sediment from West Bearskin Lake, MN (about 2% Total Organic Carbon (TOC)). Water was collected from water treatments with and without sediment for pesticide concentrations. Pesticide concentrations are reported for water and for filters plus sediment. Test organisms were exposed to pesticides for 24-hr before being assessed for survival.