The role of fish macroparasites as indicators of pollution

Research project P 14548 The role of fish macroparasites as indicators of pollution Friedrich SCHIEMER 26.6.2000 Heavy metals are considered to play an important role as xenobiotics in aquatic ecosystems. Their impact particularly on fish received considerable attention and recently studies on endohelminth, species of fish showed that especially acanthocephalans are able to accumulate high burdens of heavy metals. This project will focus on the investigation of the effects of heavy metals on endobelminths of barbel (Bartbus barbus L.) and compare the sensitivity of an established free-living invertebrate indicator (Dreissena polymorpha L.) with that of the two selected acanthocephalan -species. The study will be performed at the two locations at the River Danube and one site at the River Gailitz. Based on the concentrations and the accumulation of the selected heavy metals cadmium, lead, and zinc measured in liver, intestine and muscle of barbel, endohelminths, bivalves, water, and sediment over a period of 2 years this study will try to integrate the parameters of ecotoxicology, host and parasite ecology, and environmental factors into a holistic approach. The combined objectives will thus provide an interdisciplinary approach to investigate heavy metal effects on holst-par4site systems and the overall impact of pollutants on aquatic ecosystems.

This work focused on the on the potential of endohelminths of barbel Barbus barbus (L.) as reaction and accumulation indicators of the heavy metals cadmium, lead, and zinc in aquatic systems. Further the sensitivity of the established free-living invertebrate accumulation indicator Dreissena polymorpha (Pallas 1771) was compared with that of the acanthocephalan Pomphorhynchus laevis (Mueller, 1776), which is a common parasite of B. barbus. Sampling was conducted at sites with differing heavy metal pollution - two locations at the River Danube and one at the River Drau in the years 2001 and 2002. Based on the concentrations and the accumulation of the heavy metals measured in liver, intestine, and muscle of barbel, P. laevis, and D. polymorpha, this work tried to integrate parameters of ecotoxicology, host and parasite ecology, and environmental factors into a holistic approach. The results indicate that for the validation of the role of parasite community patterns related to heavy metal pollution more investigations on the aspects of food web dynamics, interrelationships between parasites, and the presence/absence of intermediate hosts will be essential. Heavy metal concentrations differed significantly between the organs of barbel and P. laevis with levels up to the 2860 fold in the parasite. Comparing the results of heavy metal accumulation in P. laevis with that of its host barbel there is little doubt that, despite high variability in infrapopulation age structures, host mobility and feeding behaviour in wild populations, especially this parasite can be used as a very sensitive indicator of heavy metals in aquatic systems. The comparison between P. laevis and D. polymorpha showed that the parasites accumulated all three heavy metals to a significantly higher degree than the bivalve.