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

该研究项目将获得关于新的、输出的和净群落生产的季节性周期的一套全面数据，从而更好地了解南极沿海海洋生态系统中有机物质（碳和氮）的生产和输出。 在极地地区对这三个过程的测量相对较少，在适当尺度上进行的系统的时间序列调查以揭示机制的情况更少。因此，调节新生产、NCP和出口生产的物理、生态和生物地球化学机制仍然不明确。 我们建议进行一个详细的，长达一个季度的研究，出口产量确定从水柱238 U：234 Th不平衡。新产量将通过15 NO3吸收来衡量。净群落生产将估计从测量的O2：Ar比在海水中。从10月到4月，将在距帕尔默站5公里的一个经常有人居住和长期研究（自1993年以来）的地点每周进行取样，并与帕尔默南极长期生态研究项目（PAL）正在进行的研究密切配合。每周将在两个深度部署沉积物收集器，收集颗粒，以确定沉降颗粒的C：N：234 Th比率。 这项研究将是第一批获得详细的新产品、出口产品和社区净产品的同时时间序列的研究之一。 目前对南极洲沿海微粒输出的估计仅限于几个近海地点，可能低估了一个数量级的真实输出。此外，季节和年际变化与初级生产力、海冰覆盖和浮游动物种群的相应变化没有定量关系。这些缺点可能是由于沉积物捕集器收集的缺陷和采样浮游生物群落和颗粒通量之间的时空脱节，模糊了关系。如果这些假设是正确的，该项目将提供一个新的，在南极海洋环境中的出口生产的可靠估计，以及如何以及为什么它在南方夏季生长季节变化的新解释。该项目将支持博士后研究员，并利用MBL和PAL-LTER教育和推广计划的发达基础设施，向两个最有影响力的公共教育团体，K12教师和科学记者介绍海洋碳循环和气候变化在世界上最迷人和快速变化的生态系统之一。

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.