Gray Correlation Analysis of Chlorophyll-a With Water Quality Factors in Macrobrachium rosenbergii Ponds

In order to explore relationship between chlorophyll-a and water quality factors in Macrobrachium rosenbergii rearing ponds, during the period from June to October in 2011, water quality parameters such as temperature (T), dissolved oxygen (DO), pH, transparency, nitrite nitrogen (NO₂-N), ammonia nitrogen (TAN), total nitrogen (TN), reactive phosphorus (PO₄-P), total phosphorus (TP), chlorophyll-a (Chl-a) and chemical oxygen demand (COD_Mn) in waters of 3 Macrobrachium rosenbergii Ponds and their water source in Jinshan District, Shanghai were monitored, and for the relationship of Chl-a with the other water quality factors was analyzed using the grey correlation analysis method. Results show that the correlation degree of Chl-a with the other factors displayed an order of TN＞TP＞COD_Mn＞DO＞pH＞NO₂-N＞T＞TAN＞PO₄-P＞transparency, thus demonstrating that TN, TP, COD_Mn, DO and pH were the main ones and TN and TP the most important ones affecting water quality in Macrobrachium rosenbergii ponds.