The Distribution Of Bacteria And The Relationship With Other Nutriment In The East China Sea

The organic matter that were produced by phytoplackton were assimilated by marine bacteria in order to promote the growth of the bacteria, in reverse, they supplied nutrients and necessary element for phytoplackton. Considering from the intricate relationship, the importance of bacteria was recognized while the reason and mechanism was investigated. This thesis focused on the investigations of bacteria biomass which were respectively collected from three water layers of different stations in the red tide high-incidence region of the East China Sea during the spring of 2006, 2007. The relationship between bacteria biomass and temperature, salinity, nutrient and other factors were analyzed. The trend and the reason why the bacteria biomass changed with these factors were also studied. And then the bacteria were cultivated periodically in the enriched medium where the enrichment of process was produced through the photosynthesis. During the period, the bacteria biomass and other interrelated factors were sampled and analyzed under certain temperature and time in order to study the variety of effect on bacteria. The main results are as follows: a) The results of bacteria in 2006:The twice investigations of the bacteria biomass were done from April to May in 2006, in the red tide high-incidence region of East China Sea. The result indicated that the twice biomass were respectively 0.40-4.13 (average～2.09) mgCm-3 and 0.28-4.97(～2.53) mgCm-3.The biomass decreased from Changjiang estuary to extra sea and the maximum occurred on the middle layer of each station. The average biomass increased by 21% from the second to the first.The relationship between temperature and bacteria biomass in medium water layer was well which explained the medium temperature was the main influencing factor on biomass. Another result was gained through the comparison in twice investigations. The ratio of NH4+ to DIN increased by 48%, which showed the mineralization was strengthened in second voyage.b) The results of bacteria in 2007:This investigation of the bacteria biomass was done in frequent HAB region of East China Sea in May 2007. The result indicated that the biomass were 0.24-8.19 (average～3.71) mgCm-3.The biomass decreased from Changjiang estuary to extra sea and the maximum occurred on the middle layer.The result was gained through the main component method: (1) the origins of material promoting the growth of bacteria were different between estuary and extra sea. The bacteria biomass of the extra sea stations were affected by the phytoplankton photosynthesis, while the bacteria biomass of estuary stations were also affected by the terrigenous input; (2) the changeable nature of bacteria has an effect on biomass in different layers.c) The result of cultivated in laboratoryThe heterobacteria utilized the organic matter in the medium to promote the second production and transferred the DOC, DON to the particulate forms. Under the condign temperature (20℃), when the content of DOC did not satisfy the demand of bacteria, the bacteria biomass did not increase and come into stabilization period. DOC and DON was decomposed by bacteria and released to system until the DOC was exhausted. While the temperature was 15℃, the ability of metabolism in bacteria descended and then the biomass was reduced, but other nutrient material was sufficient. Therefore, the temperature was the main limiting factor.