Discontinuous Grazing Pressure by Microzooflagellates on Marine Synechococcus

微鞭毛虫对海洋聚球藻的不连续放牧压力

• 批准号: 9203496
• 负责人: John Waterbury
• 金额: $ 36.97万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1992
• 资助国家: 美国
• 起止时间: 1992-05-15 至 1995-10-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9203496&HistoricalAwards=false
• 关键词: Discontinuous; Grazing; Pressure; Microzooflagellates; Marine

Small phytoplankton play a major role in the primary production of the oceans. The unicellular cyanobacterium Synechococcus is a prominent and important member of this community that can reach cell densities of more than 100 thousands cells per liter, achieve in situ growth rates of 3 doubling per day and as a result may contribute between 5 and 25% of the total primary productivity in the temperate and tropical oceans. Studies to date indicate that Synechococcus is grazed at rates comparable to its growth rate and that microflagellates are the major group responsible for turning over Synechococcus biomass. Synechococcus has a characteristic discontinuous pattern of diel growth both in nature and in culture that can be monitored by direct and indirect methods. Results of experiments measuring both growth and grazing rates of Synechococcus in the Sargasso Sea led to the hypothesis that grazing of Synechococcus by microflagellates can be periodic, occurring primarily at night. To test this hypothesis, Dr. Waterbury will isolate and characterize the microflagellates responsible for Synechococcus turnover and document their impact on the temporal patterns of Synechococcus abundance. The project will be conducted in both inshore and open-ocean waters and will experimentally employ culture techniques, direct and indirect measurements of in situ growth and grazing rates using direct cell counts, and C-14 bicarbonate incorporation. The significance of this study extends beyond simply furthering our understanding of the ecology of marine Synechococcus spp. This unicellular photosynthetic bacterium is an important component of the marine microbial food web. Insights concerning the identity of Synechococcus grazers and patterns and rates of grazing on Synechococcus can act as a model for and provide important insights into the workings of the "microbial loop".//

小型浮游植物在海洋初级生产中发挥着重要作用。 单细胞蓝藻聚球藻是该群落中突出且重要的成员，其细胞密度可以达到每升超过 10 万个细胞，原位生长速度可以达到每天 3 倍，因此可能贡献温带和热带海洋总初级生产力的 5% 至 25%。 迄今为止的研究表明，聚球藻的吃草速度与其生长速度相当，并且微鞭毛虫是负责聚球藻生物量转化的主要群体。 聚球藻在自然界和培养物中都具有典型的不连续昼夜生长模式，可以通过直接和间接方法进行监测。 测量马尾藻海中聚球藻的生长和放牧率的实验结果得出这样的假设：微鞭毛虫对聚球藻的放牧可能是周期性的，主要发生在夜间。 为了检验这一假设，沃特伯里博士将分离和表征负责聚球藻周转的微鞭毛虫，并记录它们对聚球藻丰度时间模式的影响。 该项目将在近海和公海水域进行，并将实验性地采用培养技术、使用直接细胞计数直接和间接测量原位生长和放牧率以及 C-14 碳酸氢盐掺入。 这项研究的意义不仅仅是进一步加深我们对海洋聚球藻属生态学的理解。 这种单细胞光合细菌是海洋微生物食物网的重要组成部分。关于聚球藻食草者的身份以及聚球藻的放牧模式和速率的见解可以作为“微生物循环”运作的模型并提供重要的见解。//