Alterations in Fish Health State Parameters after Exposure to Different Stressors

Abstract

The effect of short-term (10-day) exposure of rainbow trout (Oncorhynchus mykiss) to stimuli of different origin (natural — starvation and anthropogenic — chemicals, i. e. heavy metal mixture) as well as to their combined action on their behavioural reactions, morphological parameters and physiological indices was studied and evaluated. Both stimuli induced changes of different degrees in the studied parameters. Starvation induced more expressed changes in morphological indices (decrease in fish condition factor, tissue weight); chemicals induced changes in physiological parameters (decrease in the fish ventilation frequency, increase in “coughing” rate, erythrocyte count, and haemoglobin). Combined effects of two stimuli evoked more significant alterations in the majority of studied parameters (tissue-somatic indices, cardio-respiratory and haematological parameters). Our data suggest that joint action of the two stimuli even of low intensity (concentrations of heavy metals in mixture were similar to concentrations found in unpolluted waters of Lithuania) can disturb the homeostasis of the fish organism.