Potassium Dichromate as a Reference Substance for Embryonic Tests of Toxicity in the Common Carp (Cyprinus carpio L.)

Abstract

Potassium dichromate (K2Cr2O7) has already been used as a reference substance in tests of toxicity with aquatic animals. The aim of this study was to determine and compare values of LC50 for potassium dichromate during the whole period of embryonic development (i.e., 120 h) and 48 h after hatching of embryos in the common carp (Cyprinus carpio L.). Fish eggs and embryos were exposed to 5 different concentrations of potassium dichromate (i.e., 372, 409, 450, 495, 545 mg l-1) during two experiments. Such characteristics as the cumulative mortality, the start and the end of hatching, the number of deformities, body length, and body mass of surviving individuals were studied during the tests. The highest mortality was found in the hatched embryos. Mortality and frequency of deformities increased with the growing concentration of potassium dichromate. The value of 120 LC50 for potassium dichromate was 464.91 ± 23.83 mg l-1 and the value of 48 LC50 was 458.94 ± 4.14 mg l-1 (mean ± SD). No statistically significant difference between values 120 LC50 a 48 LC50 was found. This is why reduction of the exposure period to only 48 h after hatching seems a reasonable method to study the control of susceptibility using potassium dichromate in embryonic tests of toxicity.