Seasonal Dynamics of Giant Agglutinated Foraminifera

本研究的重点是对南极麦克默多湾探索者湾的优势胶凝有孔虫组合进行季节性研究。研究表明，该地区的凝集有孔虫(“有孔虫”)捕食各种各样的猎物，从细菌到分类上不同的后生动物，包括幼年的无脊椎动物。这些研究仅限于在10月、11月和12月初采集的标本，即紧跟在南极冬季之后和夏季冰下和底栖初级生产力爆发之前。有关有孔虫对夏季食物脉冲的反应的信息很少。这项工作的目的是利用该区域计划扩大的后勤支助。这项建议的具体目的是：记录南方春季至夏末探索者湾底栖动物中相关非生物和生物因素的变化；并描述粘合有孔虫群落结构(物种组成、密度、大小分布)中的相应反应。这些第一个目标将通过传统的沉积物取心、生物量测定和显微分选方法来实现。此外，还将使用新型水下显微镜设备现场记录细微变化。分子工具研究季节性有孔虫群落动态初步侧重于生殖事件的时序、多次分裂、配子发生等方面的完善。其他工作将集中在新改进的沉积物岩心埋藏方法上，以探索有孔虫生命位置的细尺度季节性变化。在相关的实验室实验中，将分析关键凝集物种的营养机制。从新鲜收集和“速冻”有孔虫中提取的脂类的时间分辨稳定同位素分析将被用来确定这些机制是否以及如何随着可用食物来源的变化而变化。这些结合的方法将使人们更全面地了解较大的凝集有孔虫在探索者湾底栖食物网中所起的作用，以及这些作用如何在夏季食物脉冲方面发生变化。由于勘探者湾及其粘性有孔虫组合与许多半深海和深海地区非常相似，这些研究结果将在海洋科学中具有广泛的意义。

A seasonal study of the dominant agglutinated foraminiferal assemblage in Explorers Cove, McMurdo Sound, Antarctica is the focus of this research. Studies have shown that the agglutinated foraminifera ("forams") at this locality consume a wide variety of prey, ranging from bacteria through a taxonomically diverse group of metazoans, including juvenile invertebrates. These studies have been restricted to specimens collected inOctober, November and early December, i. e., immediately following the Austral winter and beforethe summer burst of under-ice and benthic primary productivity. Little information is available regarding the foraminiferal response to this summer food pulse. The aim of this work is to utilize the planned extention of logistic support in the region. The Specific Aims of this proposal are: To document Austral spring to late- summer changes in relevant abiotic and biotic factors in the Explorers Cove benthos; and to characterize corresponding responses in agglutinated foram community structure (species composition, densities, size distribution). These first aims will be accomplished by traditional sediment coring, biomass determinations, and microscopic sorting methods. Additionally, an -situ approach for documenting fine-scale changes using novel underwater microscopy equipment will be utilized. Molecular tools to examine seasonal foram community dynamics initially focusing on the timing, of reproductive events multiple fission, gametogenesis will be perfected. Additional work will focus on newly refined sediment core embedding methods to explore the fine-scale seasonal changes in foram life position. In related lab experiments, the trophic mechanisms of the key agglutinated species will be analyzed. Time-resolved stable isotope analyses of lipids extracted from freshly collected and "snap frozen" forams will be used to determine if and how these mechanisms change in response to available food sources. These combined approaches will lead to a more complete understanding ofthe roles played by larger agglutinated forams in the Explorers Cove benthic food web, and how these roles change with respect to the summer food pulse. Because Explorers Cove and its agglutinated foram assemblage are closely comparable to many bathyal and abyssal deep-sea localities, the results of these studies will have wide significance in the ocean sciences.