Collaborative Research: Seasonal Contribution of Nano- and Microzooplankton to Antarctic Food Web Structure in the Ross Sea

96-33703 Caron本研究项目是美国联合全球海洋通量研究(JGOFS)南大洋计划的一部分，目的是(1)更好地了解南大洋有机和无机碳的通量，(2)确定调节这些通量的大小和变化的物理、生态和生物地球化学因素和过程，以及(3)将这些通量置于当代全球碳循环的背景下。近年来，微型浮游生物(2-20微米)和微型浮游原生动物(20-200微米)在世界海洋中上层食物网中的重要作用已得到确立。在这方面，已经对近海和沿海海洋生态系统进行了广泛的研究，关于热带和温带海洋生态系统微生物过程的大量信息也在积累。相比之下，纳米和微型浮游动物在通过极地群落的能量和元素流动中的作用不太清楚，因为在这些环境中采样和工作存在困难，而且普遍认为这些环境中的“经典”浮游植物-浮游动物-鱼类食物网可能会使微生物过程黯然失色。显然，现在有大量的信息与这一教义相矛盾，近年来的许多研究记录了极地生态系统中丰富而活跃的原生动物动物群。尽管如此，在我们对极地环境中微生物环的整体重要性的理解上仍有很大差距。本研究项目将探讨有关罗斯海水柱中纳米和微型浮游原生动物的生态作用的问题：(1)纳米和微型浮游原生动物是否构成罗斯海浮游动物群落的重要组成部分？(2)这些原生动物是否负责在该环境中维持低浮游植物和细菌数量？(3)混合营养(即光营养和吞噬营养)是南极浮游生态系统中原生生物生存的重要适应行为吗？将在罗斯海的年度周期内进行研究，以检验这些原生生物生态特征预期的强烈季节变化。这些研究既包括JGOFS的“核心”测量，也包括旨在确定原生动物生物量和放牧活动对罗斯海中上层食物网整体结构的季节性贡献的补充研究。

96-33703 Caron This research project is part of the US Joint Global Ocean Flux Study (JGOFS) Southern Ocean Program aimed at (1) a better understanding of the fluxes of carbon, both organic and inorganic, in the Southern Ocean, (2) identifying the physical, ecological and biogeochemical factors and processes which regulate the magnitude and variability of these fluxes, and (3) placing these fluxes into the context of the contemporary global carbon cycle. A major role for nanoplankton (2-20 um) and microplanktonic (20- 200 um) protozoa in pelagic food webs of the world ocean has been firmly established in recent years. Neritic and coastal ocean ecosystems have been extensively studied in this regard, and considerable information is also accumulating on the microbial processes of tropical and temperate oceanic ecosystems. In contrast, the role of nano-and microzooplankton in the flow of energy and elements through polar communities is less clear because of the difficulties associated with sampling and working in these environments, and because of the prevailing dogma that microbial processes may be overshadowed by `classical' phytoplankton-zooplankton-fish food webs in these environments. Clearly, there is now a great deal of information that is contradictory to this dogma, and numerous studies in recent years have documented an abundant and active protozoan fauna in polar ecosystems. Nevertheless, there are still substantial gaps in our understanding of the overall importance of the microbial loop in polar environments. This research project will examine questions concerning the ecological role of nano- and microplanktonic protozoa in the water column of the Ross Sea: (1) Do nano- and microplanktonic protozoa constitute a significant fraction of the zooplankton community in the Ross Sea? (2) Are these protozoa responsible for maintaining low phytoplankton and bacterial standing stocks in this environment? (3) Is mixotrophy (i.e., combined phototrophic and phagotrophic nutrition) an important adaptive behavior for the survival of protists in this planktonic Antarctic ecosystem? Studies will be conducted over an annual cycle in the Ross Sea in order to examine the expected strong seasonal variability in these features of protistan ecology. These studies constitute both "core" JGOFS measurements and supplementary studies designed to establish the seasonal contribution of protozoan biomass and grazing activity to the overall structure of the pelagic food web of the Ross Sea.