Study Of The Influences Of Inorganic Nutrients On Heterotrophic Bacterioplankton In Jiaozhou Bay

The method of area investigated is applied to study the influences of inorganic nutrients on the distribution of heterotrophic bacterioplankton during one year in Jiaozhou Bay. And it is used by the method of the lab experiments to simulate the field situation in order to study the influences of inorganic nutrients on the growth of heterotrophic bacterioplankton. The main results are listed as follows:Through area investigated for one year, the results show that the distribution of the abundance of heterotrophic bacterioplankton are similar to the distribution of the concentration of phosphate and ammonium in Jiaozhou Bay from 2003 to 2004, and all of them have high value in the east-north part of Jiaozhou Bay, while have low value in the middle and the inlet of Jiaozhou Bay. In four seasons of the spring, summer, fall, and winter, the concentration of both phosphate and ammonium has remarkable correlations to the bacterial abundance(BA), and they play important roles on the distribution of the BA. Except the summer, the concentration of nitrogen has unapparent correlation to the BA, and does not play an important role on the distribution of the BA. According to the distribution of the ratios between inorganic nitrate and inorganic phosphorus in four seasons, phosphate plays the most important role on the distribution of the BA. In all the environmental factors, temperature is one of the most important factors that affect the role of the inorganic nutrient on the distribution of the BA, and so does the phytoplankton. Another important factor is the quantity and the quality of the input of nitrate and phosphorus in Jiaozhou Bay.Through experiments of the addition of inorganic nutrients in the lab to simulate the field situation, results show that phosphate can greatly promote the growth of heterotrophic bacterioplankton; then is ammonium, while nitrate not only can notpromote the growth, but also limit it. On the whole, the growth of heterotrophic bacterioplankton is more affected by inorganic phosphate, and seldom affected by inorganic nitrogen. In Jiaozhou Bay, the absorption of heterotrophic bacterioplankton to phosphate is more than the releasing, and the absorption of heterotrophic bacterioplankton to nitrogen is less than the releasing, while the absorption of heterotrophic bacterioplankton to ammonium is the same as the releasing. The existences of photoplankton and protist are helpful for heterotrophic bacterioplankton to absorb and make use of inorganic nutrients to grow, and enhance the efficiency of the whole ecosystem.