title: Effects of age and coion (K+ and Na+) on the toxicity of thiocyanate to rainbow trout (Oncorhynchus mykiss) during pulse or continuous exposure.
abstract: Thiocyanate (SCN-) is released to the aquatic environment as a result of the treatment of cyanide-bearing wastes from precious-metal mining activity. During continuous exposure alevin rainbow trout (1- and 10-day-old) were approximately 90% more tolerant of SCN- than juveniles (2-month-old). Pulse exposure of alevins for periods > or = 48 hr were required before postexposure stress reduced tolerance (by approximately 30%) in the 24-hr period following exposure. In contrast, stressing of juveniles after exposures of > or= 9 hr consistently reduced tolerance by approximately 60%. While coion (K+ or Na+ for SCN- derived from either KSCN or NaSCN) had no influence on SCN- toxicity for alevins, juveniles exhibited reduced tolerance in the presence on Na+. Although sudden death syndrome was apparent in juveniles, none occurred with alevins. Overall, juveniles were less tolerant of SCN- than alevins, possibly because of the enhanced efficiency of SCN- uptake by gill respiration versus the predominantly vitelline membrane respiration of alevins.
authors.affiliation: Department of Biology, University of Waterloo, Waterloo, Ontario, N2L 3G1, Canada.
authors.forename: S D
authors.initials: SD
authors.lastname: Kevan
authors.forename: D G
authors.initials: DG
authors.lastname: Dixon
mesh_terms: D000375:Aging / Q000473:pathology*; D000818:Animals; D002414:Cations, Monovalent; D004305:Dose-Response Relationship, Drug; D007220:Industrial Waste; D007928:Lethal Dose 50; D008906:Mining; D017686:Oncorhynchus mykiss; D011041:Poisoning / Q000401:mortality; D011188:Potassium / Q000378:metabolism*; D012119:Respiration / Q000187:drug effects; D012964:Sodium / Q000378:metabolism*; D013861:Thiocyanates / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D002414:Cations, Monovalent; D007220:Industrial Waste; D013861:Thiocyanates; D014874:Water Pollutants, Chemical; D012964:Sodium; D011188:Potassium