Toxiceokinetics of 2,4,5-trichlorophenol and benzo(a)pyrene in the clam Pisidium amnicum: Effects of seasonal temperatures and trematode parasites

Several biotic and abiotic stress factors may affect aquatic organisms simu ltaneously. However, not much is known about the effects of, e.g., low temp eratures and parasite infections on the toxicokinetics of organic hydrophob ic chemicals. Here we studied the accumulation and depuration of [C-14]2,4, 5-trichlorophenol (TCP) and [H-3]benzo(a)pyrene (BaP) in the sediment-dwell ing freshwater clam Pisidium amnicum. Experiments were made in October(+15 degrees C), April (+4 degrees C), and July (+15 degrees C) both with uninfe cted clams and clams infected with Bunodera luciopercae (Trematoda). The ac cumulation rate for both chemicals was slower at 4 degrees C than at 15 deg rees C. The depuration of TCP was biphasic, and the slowest depuration occu rred at 4 degrees C. For BaP, the depuration was very slow and monophasic a t all temperatures. The highest BCFs for both chemicals were found in July at 15 degrees C. Surprisingly, the BCFs for TCP were higher in April at 4 d egrees C than in October at 15 degrees C. For BaP, no steady-state was reac hed in April. Differences in chemical toxicokinetics between the infected a nd uninfected clams were only minor. However, for both chemicals a trend of slightly lower BCFs in the infected clams was found. In conclusion, low te mperatures modify the toxicokinetics of organic chemicals in P. amnicum and the effects depend on hydrophobicity of the chemical. The effects of paras ites on toxicokinetics seem to be small.