Analysis on relationship between plankton index of biotic integrity（ P-IBI） and physical and chemical factors in cage culture waters of Buliang reservoir

We periodically monitored and analyzed the plankton and main physical and chemical factors of fish cage in the cage culture waters of“ near point”and“far point” in Buliang Reservoir，Guangxi Plankton index of biotic integrity（P-IBI） was used to evaluate the health status of two monitoring sites，and the relationship between P-IBI and main physical and chemical factors was analyzed，which could provide a reference for the sustainable development and utilization of aquatic environment based on ecological farming and analyzing the data. The P-IBI results showed that the water quality of fish cage of for point was“healthy”and“sub-health”，the water quality of near point was“sub-health”and“general”. The order of relevance of P-IBI to the water quality factor was：pH＞ DO ＞ WT ＞ SD ＞ CODMn ＞ TP ＞ NO2-N ＞ NH3-N ＞ BOD5（near point），pH ＞ SD ＞ NH3-N ＞ TP ＞ DO=NO2-N ＞ WT ＞ CODMn ＞ BOD5（far point）. In general，the health status of water quality of far point was superior to that of near point，and the water quality can be improved by moderate regulation of physical and chemical factors of water with high correlation with P-IBI index.