| In China the annual amount of nitrogenous and phosphate fertilizers were as high as 23.929 million tons(pure nitrogen) and 8.453 million tons(phosphorus pentoxide), currently, the loss of nitrogen and phosphorus in farmland is the main cause of eutrophication. Eutrophication made effect on aquatic animals, plants on the microorganism and water productivity, which was worthy of attention. Rhizoma Coptidis is an important Chinese herbal medicine and 100 to1300 ton is consumed each year. This medical plant is widely grown in Chongqing, Sichuan, and Hubei. There are largest areas for growing Coptis chinensis with a long history and about 40% of total coptis roots are produced in Chongqing. Coptis chinensis seedlings are grown under the cover made from tree branches and thus a lot of trees are cut off in the traditional cultivation, which leads to ecological damage. Simultaneously, continuous cropping obstacle occurs seriously after Coptis chinensis cultivation, since rhizoma coptidis alkaloids exist in soil and need a long time to break. As a result, 3 to 5 year fallow are necessary after harvest of Coptis chinensis. In addition, rhizoma coptidis alkaloids can enter into soils by plant residues, dropped cells, and root exudates during Coptis chinensis cultivation. Then they are feasible to dissolve in surface or underground runoff and subsequently accumulate in water. Rhizoma coptidis alkaloids present in water act with aquatic plants, animals, and microbes, which sustainably influence water ecosystems. Besides, coptis roots have anti-inflammatory and bactericidal effect, and widely used in aquaculture, which also produces accumulative effect in water and influence water ecosystems.Much research indicates the inhibitory effect of rhizoma coptidis alkaloids on the growth and reproduction of territorial plants, protozoa, and microbes. Less information, however, is available on growth and acute toxic effect on phytoplankton flora and fauna in water. Therefore, simulative incubation experiments were carried out with Oblique scenedesmus and Chlorella pyrenoidosa, the two primary aquatic predictors, and Daphnia carinata, the secondary consumer in water, to investigate the toxic effect of coptis root extracts(CRE) on these living organisms in normal and eutrophic water. The main objectives are to understand the roles of rhizoma coptidis alkaloids present in water in growth, reproduction, and physiological and biochemical processes of green algae, the influences on movement, lethal effect, reproduction, and phototaxis of daphnia. The results obtained could give us some information for evaluating the risk of over use of coptis roots and agents made from this medical herb in aquaculture on water ecosystems. Following are the main results founded:1. CRE had a significant inhibition on the growth of Oblique scenedesmus and Chlorella pyrenoidosa and the adverse effect increased with concentrations, showing inhibition at low contraction and some demise effect at moderate and high. Adding CRE into cultural solution decreased protein and chlorophyll in algae, and pH in liquid cultures but increased electrical conductivity in culture solutions. Low and moderate CRE concentrations induced the production of antioxidant enzymes. As a result, SOD activity and MDA content increased in contrast to CAT which decreased in activity when grown the algae in culture solutions at middle and low CRE concentrations.2. Eutrophic water promoted the growth and reproduction of Oblique scenedesmus and Chlorella pyrenoidosa. However, the growth and reproduction of the two green algae tended to stop at low CRE concentration(88 ?g·L-1) and died at high in same eutrophic condition, which implied more toxicity of CRE in eutrophic water. The physiological and biochemical indexes in response to CRE followed a similar trend to the alga growth and reproduction.3. CRE was obviously harmful to Daphnia carinata and significant reduced movement, survival rate, and phototaxis of daphnia. The LC50 and EC50 at 24 h were 162.20 mg·L-1and 116.87 mg·L-1, which at 48 h were 135.04 mg·L-1 and 86.94 mg·L-1, respectively. CRE concentrations that influence daphnia ranked: half lethal > half inhibitory > phototaxis-changeable limit. CRE concentration limit that led to the changes in phototaxis was only 4.27 mg·L-1. Addition, the male individuals and death rate of parents after reproduction increased, reproduction period prolonged, further generation number and young daphnia’s movement ability decreased, daphnia became transparent, and body length shortened with CRE concentrations increased. All of these findings suggest the adverse influence of CRE on the growth and reproduction.4. Negative values of phototaxis index were observed when incubating daphnia in eutrophic water with different four CRE concentrations and doubly decreased with CRE increased. Lower phototaxis indexes were founded in eutrophic water than normal at same CRE concentrations, indicating more influence of CRE on phototaxis behaviour of daphnia in eutrophic water and CRE had toxicant effect on daphnia. The LC50 and EC50 at 48 h were 131.68 mg·L-1 and 80.16 mg·L-1, respectively. |
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