STUDY OF HETEROTROPHIC BACTERIA, COLIFORM BACTERIA AND OIL DECOMPOSING BACTERIA IN THE JIAOZHOU BAY

Results of Over 8 years of experience in the determination of the bacteria in the Jiaozhou Bay was presented. It showed that the number of heterotrophic bacteria, coliform bacteria and oil decomposing bacteria in this area was high, its number was 1. 1 × 106 cell/ml, 4. 6 × 104 cell/ ml and 4. 6 ×102 cell/100ml respectively. There was a similar spacial pattern of het erotrophic bacteria and coliform bacteria, the number of these two kinds of bacteria was high in the stations near beach and city,and low in the stations either in the core bay or outside the bay. That could be charaterized by a progressive decrease in off shore direction. The data also showed that there was a regular seasonal pattern of heterotrophic bacteria and coliform bacteria, the number of these two kinds of bacteria was highest in summer, lowest in winter, and medium in spring and autumn. The seasonal number variations seemed to be mainly controlled by the water temperature. Oil decomposing bacteria did not have either temporal or spacial pattern, its number during four seasons of these 8 years in the Jiaozhou Bay had little fluctuations. The results also indicated that there was a positive correlation between heterotrophic bacteria and coliform bacteria, its relative coefficient was r2= 0. 76. The number of heterotrophic bacteria and coliform bacteria in the Jiaozhou Bay had a relationship with the supply of nutrients, such as COD, NH+4,NO-3, No-2, PO 4 and so on, It preliminarily showed that the different spacial distribution of hetertrophic bacteria and coliform bacteria was due to the supply of nutrients.