Adaptive response under multiple stress exposure in fish: From the molecular to individual level
Résumé
Aquatic systems are subjected to various sources of stress due to global changes, such as increasingtemperature and pollution. A major challenge for the next decade will be to evaluate the combinedeffects of these multiple stressors on organisms and ecosystems. For organisms submitted to chemical,biological or physical stressors, the capacity to set up an efficient adaptive response is a fundamentalprerequisite for their long-term survival and performance. In this study, goldfish (Carassius auratus) weresubjected to individual and combined pesticide mixtures and increased temperatures to evaluate theiradaptive response in multistress conditions from the molecular to the individual level. Fish were exposedfor 16 days to a mixture of pesticides at environmental relevant concentrations (S-metolachlor, isoproturon,linuron, atrazine-desethyl, aclonifen, pendimethalin and tebuconazole) and at two temperatures(22 C and 32 C). Three major physiological traits of the stress response were measured: thehormonal response (i.e. plasma cortisol), the metabolic balance from molecular to individuals' levels(metabolomics, cellular energy allocation, energy reserves and global condition indexes), and the cellulardefense system induction (SOD, CAT and GST). Results show that (1) environmentally relevant concentrationsof pesticides lead to significant responses in fish at all biological levels; (2) the metabolicresponse depends on the nature of stress (thermal vs. chemical); and (3) fish may be unable to set up anefficient adaptive response when chemical and thermal stresses were combined, with adverse outcomesat the individuals’ level.
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