The Study Of Grazing Impact On Heterotrophic Planobacteria Of Protozoan In Jiaozhou Bay

The raicroloop is one of the most important parts of the marine ecosystem, and the energy about 20%-40% of the primary productivity returns to the main food cycle through the microloop in coastal waters. Therefore, the microloop of the grazing of protozoan on planobacteria is an important complement to the main food cycle and leads to the improvement of the ecological efficiency.In the microloop, the grazing on bacteria of protozoan is the center part. The grazing of protozoan on planobacteria reveals the flow processes of energy and substance from DOC to plankton and shows the significant effect on the regeneration of nutritional salt and other inorganic elements caused by amounts of heterotrophic planobacteria in the ocean. For this reason, marine biologists pay more concerns on the populations and producting processes of marine bacteria. Many international projects, such as G10BC, JGOFS and LOICZ, make the study on marine bacteria one of their important works.Because of the important affection in adjusting the ecosystem of Qingdao of the Jiaozhou Bay, it owns great values to do some researches in the grazing of protozoan on planobacteria in both theory and practice aspects, such as clarifying the translation efficiency and the improvement of productivity of Jiaozhou Bay.In this paper, a survey of one year was conducted on the grazing impact and contribution to carbon recurrence, and further determinations and researches were done on the correlative factors influencing the grazing impact. Then, a primary discussion was carried out on the grazing impact and contribution to carbon recurrence.The distribution of heterotrophic planobacteria and protozoan is conducted in the survey of this paper. It shows that there are time dissimilarity and space dissimilarity in the distribution of planobacteria, meanwhile, the amounts of heterotrophic planobacteria are different in different sea areas and months. The conditions of theprotozoan are the same to the planobacteria' s. The average amount of heterotrophic planobacteria in the year is 9. 57X106/mL, while the amount of protozoan is 22. 47X lOVmL.The grazing speed is counted by dilution in the survey. The results shows there are time dissimilarity and space dissimilarity in the grazing speed, and the average of grazing speed is about 15. 25 u gC/d ?m3. Meanwhile, the speed will change when the season and sea area change.The grazing impact will change when the correlative factors change. Such factors include the temperature, dissolved oxygen, density of algae, density of planobacteria, distance away from bed and time: The temperature shows exponential positive correlation; the dissolved ox ygen shows linear negative correlation; the density of algae shows linear positive correlation; the speed is the quadratic function of the density of planobacteria; the speed is the cubic function of time factor; and the distance shows linear positive correlation with the speed. When it is influenced by several factors, the grazing speed is trivariate function of temperature, dissolved oxygen and distance away from bed, which are all positive correlation to the speed.The contribution of the grazing can be calculated by the formula:The contribution caused by the grazing pressure was expressed by the percentage that the carbon quantity which is grazed by the protozoan taking of the total increased carbon quantity of heterotrophic planobacteria. In this paper, that percentage is 65. 9%, which changes with change of the areas, seasons or species. The contribution is closely relative to the speed of grazing and growth speed of planobacteria. Furthermore, the environmental factors can often influence the proportion.Further researches should be carried out to make out the particular effect that other environment factors in Jiaozhou Bay put on the grazing impact and contribution to carbon recurrence.