The Temporal And Spatial Distribution Of Bacteria In The Large-scale Mariculture Of Zhelin Bay, Eastern Guangdong

Zhelin Bay with water area of 68- 70km2 is one of the most important estuaries for large-scale mariculture in the eastern Guangdong, China. Since the 1980's, mariculture increased rapidly there, which resulted in the exacerbation of estuarial eutrophication incessant depravation of ecological status . From September in 2001 to August in 2002, at the first time, the thesis investigated the spatial and temporal distribution of bacteria and the relation between bacteria and nutrient factors. The thesis analyzed their ecological status and their variational trend in the future, and will ulteriorly give basic data for studying and formulating the strategies on continuing development and estuarial protection of mariaquaculture in eastern Guangdong Province. At the same time, this can provide more valuable information on how to prevent and eliminate some disease of mariaquaculture.Locale inverstigation of chemical and physical elements of surface water layer and bottom water layer was carried out from nine station one time every month. Sampling was scheduled to cover the period around high tide(±1.5hr). Bring the sampling to the laboratory under low temperature circumstances, then, census the total numbers of bacteria by fluorescence microscope and vibrio by selection technique of plate cultivation. The results showed that the numbers of bacteria, vibrio were varying in the water and in sediment. The numbers of bacteria in the large-scale filter-feeding marine fish culture and oyster culture were more than those in the estuary and the outer bay. In addition, the seasonal variation of the bacteria was prominence, the numbers of bacteria were the most in summer, while those were the least in winter.The results showed that the numbers of bacteria were positive correlation with water temperature(r =0.8326, p<0.0001), also the positive relation exited among the dissoved of nitrogen and phosphate. While the numbers of bacteria between the dissolved oxygen(r =-0.5054, p<0.0001), zooplankton (r =-0.6125, p<0.029)wasnegative correlation .The water of Zhelin Bay was polluted seriously, and it reached the level of eutrophication or excess eutrophication.