The seasonal cycle of export production in an Antarctic coastal marine ecosystem

该研究项目将获得关于新的、出口的和净群落生产的季节周期的综合数据集，并有助于更好地了解南极沿海海洋生态系统中有机物质(C和N)的生产和出口。极地地区对这三个过程的测量相对较少，为了揭示机制而在适当尺度上进行的系统时间序列调查就更少了。因此，控制新生产、净生产和出口生产的物理、生态和生物地球化学机制仍未得到很好的描述。我们建议对根据水柱238U：234不平衡确定的出口生产进行详细的、长达一季的研究。新的产量将通过15NO3的摄入量来衡量。将通过测量海水中O2/Ar的比率来估计群落净生产量。从10月至4月，将在距离帕尔默站5公里的一个定期占用和长期研究的地点(自1993年以来)每周进行采样，密切配合南极洲帕尔默长期生态研究项目(PAL)正在进行的研究。每周将在两个深度部署沉积物捕集器以收集颗粒，以确定下沉颗粒上的C：N：234的比例。这项研究将是第一次获得新的、出口的和净社区生产的详细的并行时间序列。目前对南极洲沿海粒子出口的估计仅限于少数几个离岸地点，可能会低估真正的出口一个数量级。此外，季节和年际变化与初级生产、海冰覆盖或浮游动物种群的相应变化没有数量上的关系。这些缺陷可能是由于沉积物捕集器收集不足，以及对浮游生物群落和颗粒通量进行采样之间的时空脱节造成的，这使得关系变得模糊。如果这些假设是正确的，该项目将对南极海洋环境的出口产量提供一个新的、强有力的估计，并对南极夏季生长季的出口产量如何变化以及为什么变化做出新的解释。该项目将支持一名博士后研究员，并利用MBL和PAL-LTER教育和外联计划完善的基础设施，向两个最有影响力的公共教育群体--K12教师和科学记者--介绍世界上最吸引人和变化最快的生态系统之一的海洋碳循环和气候变化。

The research project will obtain a comprehensive data set on the seasonal cycles of new, export and net community production, and lead to a better understanding of the production and export of organic matter (C and N) in a coastal Antarctic marine ecosystem. There have been relatively few measurements of these three processes in polar regions, and even fewer systematic time-series investigations conducted at the proper scales to uncover mechanisms. In consequence, the physical, ecological and biogeochemical mechanisms regulating new production, NCP and export production remain poorly-characterized. We propose to conduct a detailed, season- long study of export production as determined from water column 238U:234Th disequilibrium. New production will be measured by 15NO3 uptake. Net community production will be estimated from measurements of the O2:Ar ratio in seawater. Sampling will be carried out weekly from October to April at a regularly-occupied and long-studied (since 1993) site 5 km from Palmer Station, in close conjunction with ongoing research by the Palmer, Antarctica Long Term Ecological Research project (PAL). Sediment traps will be deployed weekly at two depths to collect particles for determination of the ratios of C:N:234Th on sinking particles. This study will be among the first to obtain detailed concurrent time series of new, export and net community production. Current estimates of particle export in coastal Antarctica are limited to a few offshore sites and may underestimate the true export by an order of magnitude. In addition, seasonal and interannual variability are not quantitatively related to corresponding variations in primary production, sea ice cover nor zooplankton stocks. These shortcomings may result from sediment trap collection deficiencies and a spatiotemporal disconnect between sampling the plankton community and particle flux that blurs relationships. If these suppositions are correct, the project will provide a new, robust estimate of export production in the Antarctic marine environment, and a new explanation of how and why it varies during the Austral summer growing season. This project will support a postdoctoral fellow and take advantage of the well-developed infrastructure of the MBL and PAL-LTER Education and Outreach programs, to inform two of the most influential groups for public education, K12 teachers and science journalists, about the ocean carbon cycle and climate change in one of the world's most captivating and rapidly changing ecosystems.