Sensitivity of Hydrocharis morsus-ranae L. to selected metals and its suitability for phytoremediation of waters contaminated with metals. A mesocosm study

Anthropogenic pollution leads to increased concentrations of metals in the freshwater and macrophyte. Aquatic plants substantially contribute to the structure, function as well as and service provision of aquatic ecosystems. Our microcosm experiments were to test the possibility of the physiological response of Hydrocharis morsus-ranae to metal (Cd, Pb, Cu, Zn, Mn, Fe at three level of concentration) contaminated waters. Biomass was analysed at the beginning and at the end of the experiment. At the same time contents of photosynthetic pigments in leaves were estimated spectrophotometrically. We found that this macrophyte had the ability to grow in contaminated waters, but the effects of high concentration of isolated metals in water will indicate changes consisting in the disappearance of a significant part of biological populations were which manifested in alteration of the content of photosynthetic pigments as well as this plant’s growth. We show that generally stress of Zn and Cu influenced the drop of dry biomass which was connected with a positive correlation between the amount of dry biomass and the content of chlorophyll a and carotenoids, or only carotenoids, respectively. The highest stress of Pb and Fe (third concentrations of these metals) also influenced the drop of biomass. We concluded that none of Cd concentrations were toxic to this plant, but the effect of Mn stress was not unequivocal. Moreover, plant growth was stimulated by low Fe concentrations (first concentration) demonstrating the hormesis effect. When plants were exposed to this metal, there was no evidence of damage to the photosynthetic processes.