(PM212A) Effects of chlorpyrifos and esfenvalerate on juvenile Chinook salmon.
Werner, I.1, Eder, K.1, Clifford, M.1, Hedrick, R.1, 1 UC Davis, Davis, CA, USA
ABSTRACT- Insecticides have been identified as a major pollution problem in surface waters of the Sacramento and San Joaquin River watersheds. These pesticides enter surface waters in stormwater runoff from agricultural and urban areas during winter months, when juvenile Chinook salmon (Oncorhynchus tshawytscha) are migrating downstream. Although concentrations are generally below acutely toxic levels for salmon, there is concern that pesticides may be having deleterious sublethal effects. Our research focuses on sublethal effects of insecticides and their effects on the organism s susceptibility to disease. We quantified stress protein expression (hsp60, hsp70, hsp90), cytokine induction (IL-1b, TGF-b, IGF-1, Mx protein) and acetylcholinesterase enzyme activity in juvenile salmon exposed to two insecticides, the organophosphate chlorpyrifos and the pyrethroid esfenvalerate. To study the effects on the immune system and susceptibility to disease, fish were exposed to both infectious hematopoietic necrosis virus (IHNV) and pesticide. Our results suggest that sublethal levels of pollutants may act synergistcally with endemic pathogens to compromise health and survivorship of fish populations through immunologic or physiologic disruption.
Key words: salmon, insecticides, sublethal effects, IHNV