A Study Of Simulation On Phytoplankton Chlorophyll A Concentration And Primary Production In Taihu Lake

To research the growth of phytoplankton and the spatial-temporal variations of its primary production in Taihu Lake,this paper studied the effect of temperature,sunshine hours,rainfall,wind speed,total nitrogen,total phosphorus,transparency,dissolved oxygen and other environmental factors on phytoplankton based on the meteorological data of 2001-2010 and the water quality data of 2001-2006.Used the most important factors as the input variables to establish BP neural network model and multiple regression model to predict the chlorophyll concentration of phytoplankton for Huxin, and the model was validated in other different parts of Taihu lake. The primary production of Meiliang Bay from 2004 to 2005 was simulated by VGPM model,Cadee model,Talling formula, and the VGPM model was used to estimate the primary production of phytoplankton of Taihu Lake from 2001 to 2012.The results were as follows:(1) The temperature,sunshine hours,total nitrogen,total phosphorus,dissolved oxygen were the main factors affecting chlorophyll concentration of phytoplankton in Taihu Lake.(2) BP neural network model and multiple regression model were the effective tools to predict chlorophyll concentration of phytoplankton in the Taihu, and the accuracy of BP model was higher than the multiple regression model, the chlorophyll concentration of phytoplankton was simulated by models were generally higher than the actual value,the simulation value of multiple regression model were higher than the value of BP model.But the simulation accuracy of both two models were lack when the chlorophyll concentration were high,they were lower than the actual value.(3) The influence of the change of temperature and dissolved oxygen on chlorophyll concentration of phytoplankton in Taihu Lake was the most significant,and the effect of the change of total phosphorus was little.(4) All of VGPM model, Cadee model, Tailing formula can reflect the primary productivity of phytoplankton of Meiliang Bay, but the estimation accuracy of VGPM model was slightly higher than the other two models, and the estimation value of VGPM model was also higher than the other two models, but all the estimation value were lower than the measured value.(5) The annual primary productivity of phytoplankton in the year of 2001-2012 performanced increasing at first,then decreasing; the spatial distribution of the primary productivity of phytoplankton showed that northern Taihu was highest, central and northeast Taihu were lower than it, the primary productivity of phytoplankton in south and southeast of Taihu was the lowest.(6) The primary productivity of phytoplankton in Taihu Lake showed quadratic growth trend with chlorophyll concentration.