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 simultaneously. However, not much is known about the effects of, e.g., low temperatures and parasite infections on the toxicokinetics of organic hydrophobic 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-dwelling freshwater clam Pisidium amnicum. Experiments were made in October(+15 degrees C), April (+4 degrees C), and July (+15 degrees C) both with uninfected clams and clams infected with Bunodera luciopercae (Trematoda). The accumulation rate for both chemicals was slower at 4 degrees C than at 15 degrees C. The depuration of TCP was biphasic, and the slowest depuration occurred at 4 degrees C. For BaP, the depuration was very slow and monophasic at 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 degrees C than in October at 15 degrees C. For BaP, no steady-state was reached in April. Differences in chemical toxicokinetics between the infected and uninfected clams were only minor. However, for both chemicals a trend of slightly lower BCFs in the infected clams was found. In conclusion, low temperatures modify the toxicokinetics of organic chemicals in P. amnicum and the effects depend on hydrophobicity of the chemical. The effects of parasites on toxicokinetics seem to be small.