Acquisition of Moored Water Sampling Equipment to Assess the Regulation of Phytoplankton Productivity in the Ross Sea

在过去几十年的海洋学研究中，海洋学家观察到物理、生物、化学和地质过程的重大年际变化。最著名的例子是赤道太平洋的ENSO现象。众所周知，南大洋的年际变化还发生在冰的范围和浓度、食草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率方面。然而，人们对浮游植物产量的年际变化以及这些变化在食物网中所起的作用知之甚少。此外，对浮游植物生产控制的潜在年际变化一无所知。本提案寻求资金，以增加目前资助的一个项目，该项目审查罗斯海的年际变化，并收集影响南极洲罗斯海南部浮游植物季节性生产的变量的时间序列数据。该项目将在两个独立的海洋学系泊处分别增加三个仪器，以开发一个能够提供数据的系泊系统，以解决罗斯海生态系统的年际变化问题。这些新仪器包括快速重复率荧光计、全水采样器和原位硅酸分析仪。这些仪器将用于确定铁限制的时间和程度（使用光化学效率评估，这是铁限制的敏感指标），测量溶解硅酸盐吸收速率以评估硅藻在罗斯海南部的作用，以及微观确定浮游植物组合的组成。因此，对于在这种快速变化的非平衡环境中不断发生的生物变化，人们将有更深入的了解。此外，它还将评估该系统的两个主要功能类群，即硅藻和殖民地栖藻南极褐囊藻产量的年际变化。新仪器将被添加到两个现有的系泊系缆中，在地面混合层中有原位硝酸盐分析仪。这将首次在南极收集春末至夏末期间光带营养物质浓度的时间序列。通过将新仪器集成到系泊系统中，将获得辐照度限制和铁限制之间过渡时期的信息。来自新仪器的额外数据将允许对该地区硅藻的作用进行详细的时间记录。硅藻是至关重要的，因为它们被认为是主要的利爪，有助于通过南极食物网进行能量和有机物的有效转移，并显著促进生物物质向沉积物的垂直通量。产量的年际变化对罗斯海高营养层的生长和生存具有潜在的重要意义。它们对于了解该地区生物地球化学过程的自然变异性也很重要。由于像罗斯海这样的极地地区预计将受到未来气候变化的影响，生物变化也将得到预测。将这些变化置于自然变率的背景下是理解和预测这些变化的基本要素。

During the past few decades of oceanographic research, oceanographers have observed significant interannual variations in physical, biological, chemical and geological processes. The best-known example is the ENSO phenomenon in the equatorial Pacific. Interannual variations in the Southern Ocean are also known to occur in ice extent and concentration, in the composition of herbivore communities, and in bird and marine mammal distributions and reproductive success. Yet little is known about the interannual variations in production of phytoplankton or the role that these variations play in the food web. Furthermore, nothing is known concerning the potential interannual variations in the controls of phytoplankton production. This proposal seeks funds to augment a presently funded project which examines interannual variability in the Ross Sea and to collect time-series data on variables influencing the seasonal production of phytoplankton in the southern Ross Sea, Antarctica. This project will involve adding three instruments each to two independent oceanographic moorings in order to develop a mooring system capable of providing data to address the issue of interannual variability in the Ross Sea ecosystem. These new instruments include a fast repetition rate fluorometer, a whole water sampler, and an in situ silicic acid analyzer. These instruments will allow for the determination of the timing and extent of iron limitation (using an assessment of photochemical efficiency, which is a sensitive index of iron limitation), the measurement of dissolved silicate uptake rates to assess the role of diatoms in the southern Ross Sea, and the microscopic determination of the composition of the phytoplankton assemblage. Thus, insights will be obtained into the biological changes that occur continuously in such a rapidly changing, non-equilibrium environment. 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 new instruments will be added to two existing taut-line moorings with in situ nitrate analyzers moored in the surface mixed layer. These will collect for the first time in the Antarctic a time-series of euphotic zone nutrient concentrations over the late spring-summer period. By integrating the new instruments into the mooring systems, information on the period of transition between irradiance limitation and iron limitation will be obtained. Additional data from the new instruments will allow for a detailed temporal record of the role of diatoms in this region. Diatoms are critical, as they are considered to be the major talon contributing to the effect transfer of energy and organic matter through the Antarctic food web as well as significantly contributing to the vertical flux of biogenic matter to the sediments. Interannual variations of production are potentially significant the growth and survival of higher trophic levels 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.