The relationship between biotic factors and the content of chosen heavy metals (Zn, Fe, Cu and Mn) in six wild freshwater fish species collected from two lakes (Łańskie and Pluszne) located in northeastern Poland

Abstract

The effect of biotic factors as species, condition factor, body weight and total length of fish on concentrations of iron (Fe), zinc (Zn), copper (Cu) and manganese (Mn) in organs of Rutilus rutilus (L.), Abramis brama (L.), Coregonus lavaretus (L.), Esox lucius (L.), Perca fluviatilis (L.) and Tinca tinca (L.) from reservoirs of Warmia and Mazury region (northeastern Poland) were determined. Differences in the content of metals were observed between species (P ≤ 0.05). Some metals demonstrated specific affinity for particular tissues. The lower content of metals found in muscles and ranged as follows: Zn 3.427-9.950, Fe 1.297-2.550, Cu 0.133-0.279 and Mn 0.050-0.162 (expressed mg/kg wet weight). The highest content of Fe (33.49-123.6) and Cu (3.994-27.14) (except for copper in perch) in liver (P ≤ 0.05) is related to detoxification, whereas high concentration of Mn (1.366-5.113) and Zn (15.91-135.0) (except for Zn in tench) in gills may be associated with excretion processes or uptake (P ≤ 0.05). The two organs (gills and liver) may be used as bioindicators of metal contamination aquatic environments. Studies on the size and condition factor dependency of heavy metal concentrations have showed that, although the relationship is performed, in most cases was not statistically significant for organ. Metal Pollution Index (MPI) in organs of fish examined was 1.503 < MPI < 3.575. Daily consumed a 34 g portion of fish examined (per capita) is 0.317-0.624% of Fe, 1.174-3.408% of Zn, 0.455-0.955% of Cu and 0.085-0.278% of Mn of the RDA reference dose.