THE METAL UPTAKE AND ACCUMULATION IN FISH LIVING IN POLLUTED WATERS

Abstract

Fish living in polluted waters tend to accumulate heavy metals in their tissues. Generally, accumulation depends on metal concentration, time of exposure, way of metal uptake, environmental conditions (water temperature, pH, hardness, salinity), and intrinsic factors (fish age, feeding habits). Various metals show different affinity to fish tissues. Most of them accumulate mainly in liver, kidney and gills. Fish muscles, comparing to the other tissues, usually contain the lowest levels of metals. Metal distribution in various organs is time-related. Accumulation of metals in various organs of fish may cause structural lesions and functional disturbances. The results of many field studies of metal accumulation in fish living in polluted waters show that considerable amounts of various metals may be deposited in fish tissues without causing mortality. Various metals are accumulated in fish body in different amounts. These differences result from different affinity of metals to fish tissues, different uptake, deposition and excretion rates. Metal levels in live fish usually follow the ranking: Fe > Zn > Pb > Cu > Cd > Hg. The levels of Zn may be very high, up to over 300 µg/g d. w. The maximum concentrations of lead and copper are lower and usually do not exceed 10 µg/g d. w. Cadmium and mercury are accumulated by the fish in very low amounts, below 1 µg/g d.w. Metal accumulation in fish depends on pollution, and may differ for various fish species living in the same water body (for a review see Jezierska and Witeska, 2001). Generally, the higher metal concentration in the environment, the more may be taken up and accumulated by fish. Relationship between metal concentrations in fish and in the water was observed in both, field and laboratory studies (Moiseenko et al., 1995; Linde et al., 1996; Yamazaki