Pomphorhynchus laevis (Palaeacanthocephala) in the intestine of chub (Leuciscus cephalus) as an indicator of metal pollution.

Chub experimentally infected with the acanthocephalan parasite Pomphorhynchus laevis were exposed to 0.01 mg l(-1) Pb(2+) over 5 weeks. Lead was rapidly accumulated in the intestinal worms reaching a steady-state concentration after 4 weeks. This concentration was significantly greater than in the host muscle, liver and intestine and more than 9,000 times higher than the exposure concentration. Lead accumulation in P. laevis increased at a higher exposure concentration but was not correlated with either parasite intensity or with pooled or individual worm weight. The highest lead concentrations were recorded in those specimen of P. laevis that were attached in the posterior intestine. Interestingly, parasitised chub accumulated less lead in their own tissues than uninfected conspecifics. A mechanism of lead uptake by P. laevis and the application of acanthocephalans as accumulation indicators of metal pollution is discussed.