Interannual Variability in the Antarctic-Ross Sea (IVARS): Nutrients and Seasonal Production

在过去几十年的海洋学研究中，人们已经认识到，生物地球化学过程在不同年份之间存在着显著的差异。已知南大洋的年际变化发生在冰的范围和密度、草食动物群落的组成以及鸟类和海洋哺乳动物的分布和繁殖成功方面。然而，关于浮游植物产量的年际变化或这些变化在食物链中所起的作用，人们知之甚少。该项目将收集南极洲罗斯海南部浮游植物季节性生产量的时间序列数据。此外，它还将评估该系统的两个主要功能群--硅藻和南极棕囊藻--的生产量的年际变化。罗斯海为这类调查提供了一个独特的环境，原因有很多。例如，在过去十年里，通过集中若干方案，已经在罗斯海启动了事实上的时间序列。众所周知，与其他系统相比，物种多样性减少了，其季节性生产量与南极任何地方一样大。最重要的是，总浮游植物群落(及其两个功能类群)的季节生产量都可以从夏末的营养盐分布中估计出来。该项目将包括在罗斯海南部的美国海岸警卫队破冰船上进行短期巡航，允许在每五年夏末收集特定地点的水柱营养物质和颗粒物数据。此外，将部署两个停泊在15点的就地硝酸盐分析仪的系泊设备，从而首次在南极采集整个生长季真光层营养物质浓度的时间序列。所有营养数据将被用来计算罗斯海南部每年的季节性生产量，并与以前收集的信息进行比较，从而评估群落净生产量的年际变化。颗粒物数据将使我们能够估计到夏末时表层的出口量，从而计算这一生态系统过程的年际变化。季节生产量的年际变化(和生产者的主要分类群)是罗斯海食物网内营养水平较高的生长和生存的潜在重要特征。它们对于了解该区域生物地球化学过程中的自然变异性也很重要。由于预计罗斯海等极地地区将受到未来气候变化的影响，生物变化也在预料之中。把这些变化放在自然变化的背景下，是理解和预测这种变化的基本要素。因此，这项研究试图量化南极沿海系统的自然变异性，并最终了解其原因及其对罗斯海食物网和生物地球化学循环的影响。

During the past few decades of oceanographic research, it has been recognized that significant variations in biogeochemical processes occur among years. Interannual variations in the Southern Ocean are known to occur in ice extent and concentration, in the composition of herbivore communities, and in bird and marine mammal distributions and reproductive success. However, little is known about the interannual variations in production of phytoplankton or the role that these variations play in the food web. This project will collect time series data on the seasonal production of phytoplankton in the southern Ross Sea, Antarctica. Furthermore, it will assess the interannual variations of the production of the two major functional groups of the system, diatoms and Phaeocystis Antarctica, a colonial haptophyte. The Ross Sea provides a unique setting for this type of investigation for a number of reasons. For example, a de facto time-series has already been initiated in the Ross Sea through the concentration of a number of programs in the past ten years. It also is well known that the species diversity is reduced relative to other systems and its seasonal production is as great as anywhere in the Antarctic. Most importantly, seasonal production of both the total phytoplankton community (as well as its two functional groups) can be estimated from late summer nutrient profiles. The project will involve short cruises on the US Coast Guard ice breakers in the southern Ross Sea that will allow the collection of water column nutrient and particulate after data at specific locations in the late summer of each of five years. Additionally, two moorings with in situ nitrate analyzers moored at fifteen will be deployed, thus collecting for the first time in the in the Antarctic a time-series of euphotic zone nutrient concentrations over the entire growing season. All nutrient data will be used to calculate seasonal production for each year in the southern Ross Sea and compared to previously collected information, thereby providing an assessment of interannual variations in net community production. Particulate matter data will allow us to estimate the amount of export from the surface layer by late summer, and therefore calculate the interannual variability of this ecosystem process. Interannual variations of seasonal production (and of the major taxa of producers) are a potentially significant feature in the growth and survival of higher trophic levels within the food web of the Ross Sea. They are also important in order to understand the natural variability in biogeochemical processes of the region. Because polar regions such as the Ross Sea are predicted to be impacted by future climate change, biological changes are also anticipated. Placing these changes in the context of natural variability is an essential element of understanding and predicting such alterations. This research thus seeks to quantify the natural variability of an Antarctic coastal system, and ultimately understand its causes and impacts on food webs and biogeochemical cycles of the Ross Sea.