Physiological impact of acute molybdenum exposure in juvenile kokanee salmon (Oncorhynchus nerka).
A series of experiments were conducted to determine the physiological impact of acute sublethal molybdenum exposure to juvenile kokanee salmon (Oncorhynchus nerka Kennerlyi). Molybdenum was found to be relatively non-toxic to kokanee as the 96 h LC(50) was greater than 2,000 mg Mo l(-1). Exposure to either 25 or 250 mg Mo x l(-1) for 7 days was found to stimulate a significant 1.6- to 1.7-fold increase in ventilation which was later characterized to be dose-dependent between 5 and 250 mg Mo l(-1). Acute sublethal molybdenum exposure was found to have little or no impact on kokanee oxygen consumption at rest or immediately following a bout of forced activity or on physiological indicators of stress such as plasma lactate, sodium and cortisol. Despite these findings, prior exposure to 25 or 250 mg Mo l(-1) resulted in post-exercise loss of equilibrium and exercise-induced delayed mortality that were not observed in controls. Molybdenum accumulation in gill and liver of kokanee was also characterized. The findings of this study suggest that despite the non-toxic nature of molybdenum, acute sublethal exposure to this metal has physiological consequences to those fish exposed even for only a brief period. Further studies are needed to more fully elucidate the metabolism and mode of action of this metal in fish.
Reid
Scott D
SD
Department of Biology, Okanagan University College, 3333 College Way, Kelowna, British Columbia, Canada V1V 1V7. sdreid@ouc.bc.ca
D000818:Animals; D004305:Dose-Response Relationship, Drug; D005080:Exercise Test; D005880:Gills / Q000187:drug effects / Q000378:metabolism; D019344:Lactic Acid / Q000097:blood; D008099:Liver / Q000187:drug effects / Q000378:metabolism; D008982:Molybdenum / Q000493:pharmacokinetics / Q000633:toxicity*; D010101:Oxygen Consumption / Q000187:drug effects; D010805:Physical Conditioning, Animal; D012474:Salmon; D023382:Toxicity Tests, Acute
D019344:Lactic Acid; D008982:Molybdenum