单甲脒农药对模型池塘生态系统藻类群落结构的影响

在１．５－５０．０ｍｇ／Ｌ的浓度范围内，单甲脒农药对模型池塘生态系统中的浮游植物群落结构有明显影响。尤其在加药的头４ｄ内，藻类种类、数量、多样性指数、种类数比及增长率明显下降，优势比显著上升，敏感种及清洁种减少甚至消失，高浓度（５０．０ｍｇ／Ｌ）的单甲脒在２ｄ内可把藻类全部杀灭。随试验时间的延长，药物不断降解，６ｄ后藻类种类、数量、多样性指数又不断回升。随加药次数的增多，药物对藻类抑制作用明显减弱，藻类的种类、数量、多样性指数等指标不断上升，尤其是藻类数量增加明显，试验后期，藻类数量高低主要受Ｎ、Ｐ浓度大小的影响。

EFFECT OF MONOFORMAMIDINE INSECTICIDE ON ALGAL COMMUNITY STRUCTURE IN MODEL POND ECOSYSTEMS

This paper deals with the effect of N-1, 2-dimethylpheny1-N-methyl formamidine hydrochloride (DMAH)on algal community structure in model pond ecosystems of 3m3 within 90 days. Algal community structure was obviously affected by DMAH at concentration from 1. 5 to 50. 0mg/L. Especially,in the first 4 days after DMAH applied,algal species, density,diversity index, ratio of species number and growth rate were obviously reduced, but the dominant ratio was remarkably increased and sensitive and clean water species disappeared. Within 2 days all kinds of algae were killed completely when exposured to the concentration of 50 mg/L DMAH. As the experiment was continued and DMAH gradually degraded,and about 6 days later,the species,density,diversity index of algae were recovered gradually in the model pond.It was found that the inhibition of algae by DMAH was reduced gradually after DMAH applied more times at a 2 week interval. The results indicated that the raise of the index above and increase of algae was mainly related to the N. P concentration.