The Ecological Change Of Microcystin In An Eutrophic Pond And Its Inhibitory Effect On The Plant Growth

A six month-rounded investigation on the variation of contents of microcystin in algae and microcystin in water, biomass of Microcyslis bloom, physiochemical factors was conducted. Also, few clones of bacteria were separated form investigated pond while the degradation of microcystin test and the preliminary research on microcystin effects on plants growing was carried out. The results indicated that the microcystis in the investigated pond has strong toxicity. And the majority of microcystin in the pond is MC-RR as MC-LR is detected in low ratio. Both contents of microcystin in algae and in water are increasing during the water bloom. Analyzing the movement tendency of water bloom and microcystin in each phase of investigation we find that the peaks of toxicity in algae always lagged the growth peaks and the peaks of toxicity in water always lagged the peaks of toxicity in algae. Microbe in hydro-environment, nutrition condition in water and its own biomass influence the ecological changes of microcystin. There is notable relativity between the total phosphor and microcystin in algae and in water, especially the remarkable relativity for MC-RR in algae. So there is consanguineous relation between the movements of total phosphor and the production of microcystin. The microcystin in water was gradually released and reaches its peak after the water bloom faded and the peak of microcystin in algae, but it's far lower than that of in algae. The correlation analyses indicate that there is a notable correlation between the movement of microcystin in water and bacteria. A few clone bacteria have separated form the pond and the test of microcystin degradation was carried out. The test preliminarily made out the existence of degradation bacteria. In our study, several kinds of plants including maize, hybrid rice and duckweed are cultured in the medium containingmicrocystin. After 25 days aseptic culture and exposure in microcystin condition, we test several growth index including biomass, chlorophyll content, fresh weight and length of plant. The results illustrated every index tested prove that the inhibition of microcystin on plant growth is remarkable, when the medium contains microcystin (especially on high concentration).