Stanislava Mácová

Effect of nitrite on early-life stages of common carp (Cyprinus carpio L.)†

A one-month chronic exposure of common carp larvae and embryos to nitrite revealed significant (p < 0.01) differences in total accumulated mortality in fish exposed to 33, 67, and 330 mg/L NO(2)(-) compared with controls. At the highest concentration, all fish died within 8 d of exposure. On the basis of accumulated mortality in the experimental groups, lethal concentrations of nitrite were estimated at 29 d LC50 = 88 mg/L NO(2)(-); lowest-observed-effect concentration (LOEC) = 28 mg/L NO(2)(-); and no-observed-effect concentration (NOEC) = 7 mg/L NO(2)(-). Fultons condition factor values were significantly lower in fish from all experimental groups compared with controls. By day 12, fish exposed to 33 and 67 mg/L NO(2)(-) had significantly lower mass and total length compared with controls. No significant negative effects of nitrite at the concentrations tested (0.7-330 mg/L NO(2)(-), at 10 mg/L Cl(-)) on hatching or embryo viability were demonstrated, but significant differences in early ontogeny among groups were noted. Fish from all the concentrations showed a dose-related delay in development compared with the controls. Lordosis, kyphosis, scoliosis, and body shortening were observed at all concentrations and in controls, as was yolk sac deformation and edema, eye deformation, and cardiac edema. The incidence of these malformations was positively correlated with nitrite concentration. Histopathology revealed epidermal spongiosis; edema and hyperplasia of the gill epithelium, including hypertrophy and hyperplasia of eosinophilic granular cells (chloride cells); and interstitial edema of skeletal muscle in fish exposed to 67 mg/L NO(2)(-). Similar, but milder, changes were observed at lower nitrite concentrations.

Leeches as Sensor-bioindicators of River Contamination by PCBs

The aim of the study was to evaluate the use of leeches of the genus Erpobdella as a means of assessing polychlorinated biphenyl contamination of watercourses. The River Skalice, heavily contaminated with PCBs, was selected as a model. The source of contamination was a road gravel processing factory in Rožmitál pod Třemšínem from which an estimated 1 metric ton of PCBs leaked in 1986. Levels of PCB were measured in leeches collected between 1992 to 2003 from 11 sites covering about 50 km of the river (the first sampling site upstream to the source of contamination and 10 sites downstream). The PCB indicator congeners IUPA no. 28, 52, 101, 118, 138, 153, and 180 were measured. Levels were highest at the four sampling sites nearest the source of pollution. The highest values of PCB congeners were found in 1992. PCB content decreased from 1992 to 2003 and with distance from the source. The study indicated that leeches of the genus Erpobdella are a suitable bioindicator of contamination in the surface layer of river sediments.