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2B - Natural Stressors and Toxicants (TUP/73) Effects of UV-B and UV-B induced phototoxicity of retene to larvae of boreal fishes. Häkkinen, Jani1, Vehniäinen, Eeva 1, Oikari, Aimo1, 1 University of Jyväskylä, Jyväskylä, Central Finland, Finland ABSTRACT- Histopathology, Neurological disorders, phototoxicity, retene, UV-B. It has been widely documented that resin acids discharged in BKMEs are accumulating to the sediments of receiving lake areas, being further aromatised to retene under anaerobic conditions. Fish larvae may be exposed to increased UV-B radiation alone, or in addition, to polycyclic aromatic hydrocarbons such as retene (7- isopropyl-1-methylphenanthrene) at the egg or larval stages. Series of experiments were conducted in order to investigate whether increased UV-B radiation is a risk factor for early life stages of freshwater fishes. Further, studies with retene were made in the laboratory and under field conditions to find out if retene evokes lethal or sublethal phototoxicity in newly hatched larvae of spring-hatching freshwater fish species.Newly hatched larvae of whitefish and northern pike differed substantially in their reactions to UV-photoinduced toxicity retene. Overall, it can be suggested that for post-hatch larvae of coregonids the synergism of UV-B and retene is a potential ecotoxicological risk to be taken into consideration in lake areas chemically contaminated by pulp and paper industry. On the contrary, UV alone had only minor effects on coregonid larvae. Further, retene (up to 100 micrograms per litre) had no toxic or phototoxic effects to the pike. However, pike larvae were very sensitive to UV-B in laboratory conditions even in low UV-B doses, indicated as severe neurological disorders named spiral swimming. Monitoring of animals with the behavioural syndrome revealed substantial late mortality. Interestingly, field experiments with pike suggest that only minor increase to ambient UV-B coming on the earth's surface may cause sublethal effects to larval fish. However, the frequency of behavioural disorders was considerably lower in the field than in laboratory conditions. Acknowledgements We thank Mervi Koistinen for laboratory assistance. This research was supported by the Academy of Finland (Figare/Solar-project). Key words: Neurological disorders, Histopathology, retene, UV-B |
