Cambios en la velocidad de nado como indicador del efecto tóxico del cadmio en Astyanax fasciatus y Australoheros facetum

Abstract

Numerous studies have shown that the swimming performance parameters of fish may be useful indicators of their environmental stress. The swimming speed was evaluated in two Pampean species and its alteration as a result of their exposure to sublethal Cadmium concentrations. The swimming speed was calculated from a daily registry of the distance and the time of displacement of fish by means of special software. Juveniles specimens of Astyanax fasciatus and Australoheros facetum were used in the assays; fish were acclimated during 7 days in aereated fresh-water (FW), at constant temperature (20 ± 1ºC) and photoperiod (12D:12N). The experimental design contemplated three successive periods: Control (4 days in FW), Exposure (4 days in FW + 0.3 and 0.5 mg Cd L-1) and Recovery (7 days in FW); simultaneously the speed of individuals maintained in FW during 15 days (CoP) was determined. The swimming speed in both species increased in the Exposure period. After transfer to clean media (Recovery period), the altered values in A. facetum, exhibited a slight tendency to recovery (but without reaching the basal values registered in the Control period). In A. fasciatus a clear cut recovery response was registered in fish exposed to 0.3 mg. L-1 while in animals exposed to the highest concentration of Cd no recovery was registered. These differences were interpreted as evidences of dissimilar uptake and depuration rates of the toxic.