Growth characteristics of the heterotrophic bacterial population of water and bottom sediments in tanks under different trophic conditions

Treatment of single and double doses of fertilizers had a definite response on the bacterial population of water and bottom sediments in tanks after 7 days (F_2,21 3.61; P < 0.05), but did not cause any significant change after day 32 (F_2,18 1.67; P > 0.05). Although the generation time of water bacteria did not vary much in these treatments of trophic gradients (P > 0.05), there was always a distinct variation (P < 0.01) in the generation time of the bacterial population of bottom sediments. The population size of water bacteria was shown to maintain an inverse relationship with the diurnal variation of temperature (P < 0.05) and dissolved oxygen (P < 0.05) of the water. The changes in the size of the bacterial population of water were positively correlated with the variations of hardness (P < 0.05), chloride (P < 0.05) and ammonia nitrogen (P < 0.05) of water. Although the relationships between the heterotrophic bacterial population and the inorganic phosphate of water was not convincing (P > 0.05), an inverse relationship was established between the bacterial community of bottom sediments and the phosphate content of the water (P < 0.01).