Using of biocide Diazinon 60 EC in fish farming and its toxicity for fish and another water organisms

Diazinon 60 EC (chemical insecticide, organophosphate, active substance diazinon at a concentration of 600 g/l) is used in fish-farming in well-founded cases as a biocide to supress excessive propagation of coarse daphnian zooplankton (used concentration of Diazinon 60 EC 0,010 mg/l). Diazinon 60 EC is highly toxic for daphnian zooplankton (48hEC50 = 0,00029 mg/l by the using of artificially prepared adulterating water according to the standard and 48hEC50 = 0,0029 mg/l by the using of pond water). Toxicity of Diazinon 60 EC is markedly lower for other water organisms (96hLC50 for Poecilia reticulata, Cyprinus carpio and Orcorhynchus mykiss are in the range 3-10 mg/l and 72hIC50 for Desmodesmus subspicatus = 10 mg/l). At the concentration of 0,01 mg/l (i.e. 100 g per 1 ha at 1 m mean depth of the pond), Diazinon 60 EC can highly selectively eliminate daphnian zooplankton, causes no harm to fish and is reltively quickly decomposed in the aquatic environment

OF SODIUM NITRITE FOR SPINY-CHEEK CRAYFISH (ORCONECTES LIMOSUS RAF.) THE EFFECT OF CHLORIDE CONTENT IN WATER ON THE TOXICITY

Toxicity of sodium nitrite for the spiny-cheek crayfish (Orconectes limosus) was assessed in relation to the concentration of chlorides diluted in water. Results of the tests confirmed a favourable effect of chloride content in water on the tolerance of spiny-cheek crayfish to nitrites. The 96hLC50 value of 4.8 mg l-1, 17.7 mg l-1, 34.7 mg l-1, 50.5 mg l-1, 74.4 mg l-1, and 96.6 mg l-1 N-NO2- found out in individual tests corresponded, respectively to a chloride content of 11, 40, 100, 200, 300 and 400 mg l-1 Cl-in diluting water. Linear relationship of the 96hLC50 values on chloride concentration (y = 0.23 ×+ 7) was proven statistically (R = 0.995)

Toxicity of the organophosphate pesticide diazinon to crayfish of differing age

Diazinon is a widely applied agricultural pesticide whose effect importantly on the environment and the possible contamination of surface waters has led to increased interest in toxicological studies. Crayfish, as an ecologically important benthic macroinvertebrate, seems to be an appropriate model organism for such assessments. Acute toxicity tests were carried out on three crayfish age groups: young-of-the-year (total length = 25.0 ± 4.9 mm), juvenile (total length = 56.5 ± 3.8 mm) and adult (total length = 83.5 ± 5.7 mm). Young-of-the-year crayfish were found to be the most sensitive to diazinon (96 h LC50 = 0.15 mg L-1), followed by juvenile crayfish (96 h LC50 = 0.27 mg L-1), and adults (96 h LC50 = 0.51 mg L-1). Crayfish were highly sensitive to diazinon. A delayed effect of Diazinon 60EC on adults was detected (144 h LC50 = 0.44 mg L-1) suggests functional damage from the use of sublethal concentrations