Research on Antarctic Coastal Ecosystem Rates (RACER): Microbial Dynamics and Carbon Flux

尽管环境条件恶劣（低温、长时间的持续黑暗、地表水的深层垂直混合），南大洋仍保持着适度但不完整的生物生产力。南极沿海生态系统的初级生产的特点是由于水柱稳定性和太阳辐射可用性同时增加而引起的密集的春季水华。水华持续的时间一般不超过2-3个月，在此期间，南极沿海生态系统吸收了大约70-90%的年有机碳产量。这种固定碳的时间脉冲的净效应是增加所有营养水平的生物生产力，从细菌到须鲸。然而，碳转移的确切途径、速率和机制尚未得到详细的研究。特别是，微异养生物在南极食物网中的作用和浮游植物生产的直接命运需要阐明。作为南极海岸生态系统速率研究（RACER）计划的一部分，该项目将基于将水柱的物理特征与生物生产力的时间脉冲联系起来的中心工作假设，评估几个生态预测。研究工作将试图确定光自养和异养种群之间耦合的机制、途径和速率，并评估中上层和底栖生境之间的耦合。在这次考察中获得的数据将有助于全面了解初级和次级生产的速度，并最终用于制定南极沿海生态系统中碳和能量流动的一般模型。

The southern ocean maintains a moderate, but patchy, biological productivity in spite of harsh environmental conditions (low temperature, extended periods of constant darkness, deep vertical mixing of surface waters). Primary production in coastal Antarctic ecosystems is characterized by an intensive spring bloom which is initiated by a simultaneous increase in water column stability and availability of solar radiation. The duration of the bloom is generally less than 2-3 months, during which time the coastal Antarctic ecosystem receives approximately 70-90% of its annual organic carbon production. The net effect of this temporal pulse of fixed carbon is to increase biological productivity at all trophic levels, from bacteria to baleen whales. However, the precise pathways of carbon transfer, and the rates and mechanisms involved therein have not been carefully investigated. In particular, the role of microheterotrophs in Antarctic foodwebs and the immediate fate of phytoplankton production need to be elucidated. As part of the RACER (Research on Antarctic Coastal Ecosystem Rates) program, this project will evaluate several ecological predictions based upon central working hypotheses which relate physical characteristics of the water column to the temporal pulse of biological productivity. Research efforts will attempt to define the mechanisms, pathways and rates of coupling between photoautotrophic and heterotrophic populations and to evaluate the coupling between the pelagic and benthic habitats. The data obtained during this expedition will add to an overall understanding of the rates of primary and secondary production, and will ultimately be used to formulate a general model of carbon and energy flow in Antarctic coastal ecosystems.