Collaborative Research: Coupled Carbon and Phosphorus Cycling

尽管对于浮游系统，碳和营养物质通量之间的关系以及由此产生的主要生物量的元素比例已经得到了很好的研究，但对于底栖生态系统中碳和不同营养循环的耦合程度，人们知之甚少。珊瑚礁是以底栖生物为主的生态系统的极好例子，在这种生态系统中，碳和营养循环的耦合，特别是磷，可能很强，也可能很弱。因此，基本的问题是，珊瑚礁群落的净碳生产和磷同化动力学是否是独立强迫的，导致珊瑚礁上的C：P差异很大，或者在营养限制的经典模型中，净碳生产是否只是通过优势生物量的C：P比率来追随磷的同化速率。该项目结合了夏威夷大学的两名珊瑚礁生物化学学家和斯坦福大学的一名水动力学家的专业知识，以跨学科的方法解决这一问题。在长达一年的时间里，将根据海水化学成分的变化来测量碳和磷的通量，这些海水流经夏威夷卡内奥赫湾大堡礁上的一个礁坪上的控制体积。第二个目标是更好地了解波浪驱动的洋流和斯托克斯漂移在珊瑚礁水域净输送中的基本作用。这些结果将把以前使用水槽获得的知识及其确定的流动特性推广到现场，在现代仪器出现之前，只有有限的数据能够解决控制体积边界上的水流问题。该项目的更广泛影响包括增进对不同条件下底栖珊瑚礁群落的生产力和组成如何变化的了解，因此将向负责将其作为自然资源进行管理的代理人和机构提供有用的知识。该项目还将与夏威夷大学科学家参与的现有NOAA项目相互支持，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长交流。最后，该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.