| The spatial and seasonal variation in numbers of the culturable bacteria and the Vibrio community and nine environmental factors (Temperature, Salinity, pH, Dissolved oxygen, Chemical oxygen demand, Ammonia nitrogen, Inorganic phosphorus, Nitrite nitrogen, Chlorophyll a) in the surface seawater from culture areas of Zhanjiang Port were investigated from December, 2008 to November, 2009 in twelve months. Moreover, the correlation between bacterial indices and environmental factors were anlyzed, and the environment quality of the culture area was assessed. The distribution of the population of the culturable Vibrio was applied to evaluate the quality of the studied area. Based on above results, a preliminary method was established to assess the quality of harbors. The main results were as follows:1 The dynamic change of bacteria in surface seawater1.1 The spatial and temporal distribution of heterotrophic bacteria in surface seawaterThe highest population of heterotrophic bacteria in surface seawater was recorded during summer and autumn, and the second highest population occurred in spring, and the lowest was in winter. The number of heterotrophic bacteria increased because of nutrient-rich, land-rich water, pollution of water and emergence of fish diseases. Moreover, the higher density of heterotrophic bacteria appeared in those sations which is the heavily polluted area or with the weak exchange capability of water. There are three peaks for heterotrophic bacteria including the warming temperature period (3-4 months), the period with sufficient land-water (July-August) and the drop temperature period (October-November). Their characteristics are nutrient-rich and polluted.1.2 The spatial and temporal distribution of Vibrio in surface seawaterThe highest population of Vibrio in surface seawater was recorded during summer, and the second highest population occurred in autumn, and the lowest were in winter, which is little difference with heterotrophic bacteria. The spatial and temporal distribution of heterotrophic bacteria and Vibrio is positive significant correlation (P <0.05).2 Correlation between bacteria and seawater2.1 The correlation between bacteria and environmental factors The value of heterotrophic bacteria and Vibrio was closely positively correlated with temperature, ammonia nitrogen, nitrite nitrogen, inorganic phosphorus and chlorophyll a (P<0.05), but significantly reversely correlated with the value of salinity and dissolved oxygen (P<0.05). And they were no significant correlation with pH, COD.2.2 The assessment of seawater quality using bacteria as standardAccording to the results of heterotrophic bacteria, it was clear that pollution of Zhanjiang Port changed regularly with seasons. Results indicated that the water quality was polluted seriously in summer and autumn, but moderate-polluted in winter.3 The evaluation of environmental quality with Vibrio3.1 429 Bacteria strains were isolated from the culture area in Zhanjiang Port, including 297 Vibrio strains. 14 Vibrios were identified, including six major Vibrio species (Vibrio harveyi, Vibrio fischeri, Vibrio parahaemolyticus, Vibrio metschnikovi, Vibrio alginolyticus and Vibrio cholerae), and four mojor pathogenic Vibrio (Vibrio harveyi, Vibrio parahaemolyticus, Vibrio alginolyticus and Vibrio cholerae).3.2 The value of Vibrio harveyi and Vibrio parahaemolyticus was closely positively correlated with COD, ammonia nitrogen, nitrite nitrogen, inorganic phosphorus and chlorophyll a. But Vibrio fischeri has a significantly reverse correlation with COD, ammonia nitrogen, nitrite nitrogen, inorganic phosphorus and chlorophyll a.3.3 Vibrio fischeri was the dominant species in winter with good water environment in Zhanjiang Port. But Vibrio harveyi was the dominant species in summer, autumn and spring with serious polluted water. Therefore, two bacterias who are dominant in water can be used as a basis for evaluating water quality. But further research is needed to confirm it because of little information on it.
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