Developmental and subcellular effects of chronic exposure to sub-lethal concentrations of ammonia, PAH and PCP mixtures in brown trout (Salmo trutta f. fario L.) early life stages.

Brown trout (Salmo trutta f. fario L.) early life stages were studied for physiological effects caused by chronic exposure to sub-acute levels of unionised ammonia, a mixture of PCP and PAHs, and a combination of ammonia and the mixture of organics during the entire embryonic development. Nominal concentrations of tested compounds were based on field data. Accumulation data for PAHs and PCP in trout tissue reflected respective water concentrations of PCP and PAHs. Physiological responses were studied by early life stage tests (ELST) and by the analysis of the 70 kDa stress protein (hsp70). Endpoint responses in the ELST were: accelerated development, pre-hatching, and increased heart rates. For these endpoints, response levels were highest in the ammonia treatment, followed by the exposure to the PCP/PAH mixture. Weight was reduced in embryos treated with the PCP/PAH mixture, but not in the group treated with this mixture combined with ammonia. Induction of hsp70 by the test agents was found to be stage-specific with increased response levels at advanced developmental stages. In both the ELST and hsp70 analysis, response levels were lower in the combined ammonia/PCP/PAH treatment than in groups treated with either ammonia or the PCP/PAH mixture alone.