A comparative investigation on the acute
phototoxicity of
retene to vendace (Coregonus albula) and whitefish (C. lavaretus), both having pelagial larvae in spring, was conducted. To test the concept of early warning of sublethal
biomarkers in relation to lethality to posthatch stages, we examined the effects of ultraviolet-B (UV-B) and
retene on the levels of
cytochrome P4501A (CYP1A) and
heat shock protein 70 (HSP70) by exposing the animals to elevated levels of these factors for 48 and 72 h, respectively. Whereas UV-B and
retene on their own were not lethal, simultaneous
retene and UV-B exposure caused very high mortality to both species. The median lethal concentration (LC50; i.e., the concentration at which half of the larvae died) of
retene as a precursor was 41 g/L for vendace and 15 to 16 microg/L, depending on the UV-B dose, for whitefish.
Retene evoked substantial induction of CYP1A in larvae of both species, and UV-B induced CYP1A in whitefish. In vendace, no effect on HSP70 levels by any factor was observed. In whitefish, however, UV-B radiation and water
retene alone upregulated HSP70, but no additive response was detected. The CYPIA is a
biomarker of exposure to
retene in both species. The HSP70 is an early warning signal of UV-B exposure in whitefish. As a species, vendace appears to be more resistant than whitefish to the
phototoxicity of
retene, as indicated by the higher tolerance.