The changes occurring in the respiratory functions of tigerperch (Terapon jarbua) were examined in order to evaluate the toxic effects of linear alkylbenzene sulfonate (LAS). Three approaches i.e. LC50, respiratory curve, and pathomorphological changes in gills were measured after exposure to sublethal concentrations of LAS. The detergent treatment was observed to be accompanied by a significant decrease in respiratory rate from 0.018 ppm/min to 0.012 ppm/min, when LAS concentration changed from 3.5 ppm to 5.0 ppm. The destruction of secondary lamella in gill epithelium was found through means of non-parametric statistic method (McCormick 1989) to become significant when LAS concentration reached 2.5 ppm. The 24 hr LC50 value was 3.28 ppm as obtained by probability mortality method. The toxic effects of LAS on the respiratory functions have been reflected by the changes in both respiratory rates and the damage of gill epithelium. Thus, lethal was probably caused by the decreasing performance of the respiratory function.
LC50, Oxygen consumption curve, Histopathology, Estuarine fish
