Acute effects of the sodium salt of 2,4-D on the early developmental stages of bleak, Alburnm alburnus

The acute effects of a herbicide based on 2,4-D on embryos and larvae of bleak, Alburnus alburnus L. exposed to concentrations of 25–3200 mg 1^?1 for 12–48 hours were investigated. The 2,4-D delayed or stopped the development of embryos in their early stages, caused behavioural changes and morphological alterations. The L.C.₅₀ values for embryos varied between 12–9 and 15·9–4mg 1^?1 and for larvae from 51·6 to 111·2mg 1^?1 according to the time of exposure. The level of 2,4-D in Lake Balaton, or similar shallow lakes, without substantial injury of the littoral fish fauna should not surpass 0·5–1·0 mg 1^?1.