Collaborative Research: Coupled Carbon and Phosphorus Cycling

尽管在浮游生物系统中，碳和养分通量之间的关系以及由此产生的优势生物量元素比例已经得到了相当充分的研究，但在底栖生态系统中，碳和不同养分循环的耦合程度却知之甚少。珊瑚礁是以底栖生物为主的生态系统的极好例子，其中碳和营养循环，特别是磷的耦合可能非常强，也可能非常弱。因此，出现了一个基本问题：珊瑚礁群落的净碳生产和磷同化动力学是否被独立强迫，导致珊瑚礁上的C:P变化很大，或者在一个经典的营养限制模型中，净碳生产是否仅仅遵循通过优势生物量的C:P比率进行的磷同化速率。该项目结合了夏威夷大学的两位珊瑚礁生物化学家和斯坦福大学的一位水动力学家的专业知识，采用跨学科的方法来解决这个问题。在为期一年的时间里，碳和磷的通量将通过海水化学成分的变化来测量，海水流经夏威夷卡内奥赫湾堡礁的一个控制体积。第二个目标是更好地理解波浪驱动的洋流和斯托克斯漂移在珊瑚礁间净水输送中的基本作用。这些结果将把从先前使用具有确定流动特性的水槽的工作中获得的知识扩展到在能够解决穿越控制体积边界的水流的现代仪器出现之前只有有限数据的领域。该项目的更广泛影响包括提高对底栖珊瑚礁群落的生产力和组成在不同条件下如何变化的理解，因此将为负责将底栖珊瑚礁作为自然资源进行管理的代理人和机构提供有用的知识。该项目还将与美国国家海洋和大气管理局现有的一个项目相互支持，夏威夷大学的科学家参与了该项目，促进和发展整个太平洋地区沿海海洋科学家之间的技术专门知识交流。最后，这个项目将为夏威夷大学和斯坦福大学的研究生和本科生提供宝贵的实地经验。

ABSTRACTOCE-0453117Although the relationship between carbon and nutrient fluxes, and the resulting elemental ratio of dominant biomass has been reasonably well-studied for planktonic systems, little is known about the extent to which carbon and different nutrient cycles are coupled in benthic ecosystems. Coral reefs are excellent examples of benthic-dominated ecosystems in which coupling of carbon and nutrient cycles, in particular phosphorus, could be very strong or very weak. Thus, the fundamental question arises of whether the kinetics of net carbon production and phosphorus assimilation by reef communities are independently forced, resulting in widely varying C:P on reefs, or whether net carbon production simply follows rates of phosphorus assimilation through the C:P ratio of the dominant biomass in a classic model of nutrient limitation. This project combines the expertise of two coral reef biogechemists from the University of Hawaii, with that of a hydrodynamicist from Stanford University, in an interdisciplinary approach to resolve this issue. Over a year-long period, carbon and phosphorus fluxes will be measured from changes in the chemical composition of seawater moving through a control volume on a reef flat on the Kaneohe Bay Barrier Reef, Hawaii. The secondary objective is to better understand the fundamental role of wave-driven currents and Stokes drift in the net transport of water across coral reefs. These results would extend knowledge gained from prior work using flumes, with their defined flow characteristics, to the field where there has only been limited data taken prior to the advent of modern instrumentation capable of resolving water flows across the control volume boundaries. The broader Impacts of this project include improving understanding of how the productivity and composition of benthic reef communities vary under different conditions and will, therefore, provide useful knowledge to agents and agencies responsible for their management as natural resources. The project will also find mutual support with an existing NOAA program for which the University of Hawaii scientists are participants that promotes and develops the exchange of technological expertise between coastal marine scientists throughout the entire Pacific region. Finally, this project will provide valuable field experience to graduate and undergraduate students at the University of Hawaii and Stanford University.