PARENT SESSION
PT1 - Aquatic Toxicology
Tuesday, 19 November 2002
8:00 AM to 6:30 PM
Exhibit Hall

(P496) Avoidance response of rainbow trout (Oncorhynchus mykiss) to long-term forest fire retardants.

Wells, Jason^*,1, Little, Edward¹, Calfee, Robin¹, ¹ USGS, Columbia, MO, USA

ABSTRACT- Long-term forest fire retardants are composed of ammonium phosphates and sulfates, colorants, corrosion inhibitors, thickeners, and other additives. These chemicals are often applied in relatively pristine and environmentally sensitive areas that are potentially inhabited by endangered or threatened aquatic species. Avoidance of contaminants is an adaptive behavior that often reduces exposure to harmful conditions. We evaluated the avoidance responses of rainbow trout (Oncorhynchus mykiss) to the fire retardants and alternate constituent formulations ranging from 0.65 to 26 mg/L. Counter-current avoidance chambers were used in a flow-through design with receiving water at each end and a drain at the center to create a distinct boundary between treatment water and reference water. Rainbow trout consistently avoided water treated with retardants at concentrations above 0.65 mg/L. Iron oxide colorant and corrosion inhibitor (sodium ferrocyanide) did not contribute to the avoidance of retardants at the formulation concentrations we evaluated. Avoidance responses of rainbow trout were correlated to the salinity of the test water (r²=0.9990) and were significantly related to retardant concentration. Results indicate that rainbow trout would escape chemical gradients of retardants in the field. Avoidance responses may differ among species and lifestages of the same species, and competing biological drives may override the response. Environmental variables such as ash plumes and heightened temperatures could inhibit avoidance responses.

Key words: avoidance, behavior, fire retardants, Oncorhynchus