**4. Conclusions**

**Figure 3.** PCB concentrations in the tissues/organs of infected and uninfected fish and in *Acanthocephalus lucii* (Para‐

PCB 153 predominated in acanthocephalans (as in the fish), followed by PCB 138 and 180 (Table 4). Notably, the concentration of PCB 28 was approximately 10-fold higher in the

PCB 28 2.9 2.9 2.0 5.0 3.2 20.9 PCB 52 6.3 2.5 5.4 4.1 4.6 7.2 PCB 101 16.8 10.2 20.0 11.7 14.7 36.2 PCB 138 26.9 17.5 22.9 15.9 20.8 61.4 PCB 153 31.4 28.4 24.6 22.1 26.6 63.6 PCB 180 23.8 19.0 21.9 17.1 20.5 47.2 ∑PCB 108.1 80.5 96.9 75.9 90.3 237.0

**Table 4.** Mean and total (∑PCB) concentrations (mg kg–1 lipid wt) of the congeners in various tissues/organs of perch

The numbers of fish tissue/organ samples were too low for reliable statistical analysis (10 samples from infected and 14 samples from uninfected fish), but the results indicated much lower quantities of PCBs in all tissues/organs from the fish infected with acanthocephalans. The concentrations of PCBs were approximately 20- and 3-fold lower in the liver and muscles,

**Muscle Liver Adipose tissue Kidney Brain Parasite**

site). *Abbreviations*: Musc, muscle; Liv, liver; Kidn, kidney; AT, adipose tissue [27].

14 Emerging Pollutants in the Environment - Current and Further Implications

(*P. fluviatilis*) and in its intestinal parasite (*A. lucii*) [27].

respectively, of the infected perch (Fig. 3).

parasites than in the muscles, liver and adipose tissue of the perch (Table 4).

Our results demonstrated a persistent problem with the "old environmental heritage" of PCBs, leading to high risks mainly for predatory fish species in aquatic ecosystems, and for the human populations living near these regions. The commercial production of PCBs has been banned or severely restricted in Slovakia since the 1980s, but the fish in the Zemplínska šírava reservoir continue to accumulate these chemicals from the sediments polluted in the previous decades. Critical PCB levels recorded in fishes and the tendency of bioaccumulation in some species in the reservoir are essential for predicting which food webs are at risk for higher rates of bioaccumulation that endanger the health of upper-trophic predators, including humans living in the area. This study indicated that the different fishes, their dietary intakes and the chemical properties of the pollutants were interrelated factors, all of which were important in the tissue/organ burdens. Fish parasites, due to their good properties of bioaccumulation and position in the food chain, should be carefully considered in any ecotoxicological research.

### **Acknowledgements**

We thank Dr. Ľudmila Turčeková for her cooperation in collecting fish samples and Dr. William Blackhall for his editorial comments on the text. We gratefully acknowledge the funding of this study by the Slovak Research and Development Agency, project No. LPP-0151-07, Grant Agency of the Ministry of Education of the Slovak Republic, and Slovak Academy of Sciences (VEGA), project No. 2/0080/10. The publication has been realized as part of the project of the Centre of Excellence for Parasitology (Code ITMS: 26220120022) supported by Operational Programme "Research & Development" funded by the European Regional Development Fund (rate 0.9).
