JGOFS: Carbon Flow Through The Microbial Loop in the Arabian Sea: Heterotrophic Nanoplankton Growth Rates and Picoplankton Grazing

微尺度生物（0.2 ~ 2.0um）在海洋浮游生物群落的生产和生活生物量中占有非常重要的一部分。这些大小类别的光合微生物（蓝藻、原绿藻和一些小型真核藻类）的初级产量是浮游生物初级总产量的主要贡献者。同样，最近的证据表明，细菌可能是许多远洋生态系统中最大的生物生物量的单一储存库。总的来说，这些组合的活动和命运强烈地影响着海洋中能量和生物活性元素的流动。由于这些组合通常比后生浮游动物有效捕获的颗粒要小，因此将这些微生物重新包装成更大的消费者是将它们纳入远洋食物网的基本步骤。在纳米浮游生物大小范围内的原生生物消费者（主要是鞭毛原生动物~ 20um大小）作为微浮游生物组合（细菌和光养生物）的主要消费者在浮游生物群落中起着关键作用。然而，关于海洋环境中细菌和小型浮游植物的消耗速度，或关于原生生物消费者的生长和生产速度的资料仍然很少。作为美国在阿拉伯海进行的全球海洋通量联合研究的一部分，卡隆博士将进行实验，调查海洋环境中表层水和最低氧层的纳米浮游生物消费者的放牧率和产量。这项工作的总体目标是通过微生物浮游生物的第一次营养相互作用来量化碳流。

9310693 Caron Pico-sized organisms (organisms 0.2 - 2.0um) constitute a very significant portion of the production and living biomass of oceanic plankton communities. Primary production by photosynthetic microorganisms in these size classes (cyanobacteria, prochlorophytes, some small eukaryotic algae) are major contributors to total primary production in the plankton. Likewise, recent evidence suggests that bacteria may be the largest single repository of living biomass in many pelagic ecosystems. Collectively, the activities and fates of these assemblages strongly influence the flow of energy and biologically reactive elements in the ocean. Because these assemblages are generally smaller than the particles captured efficiently by metazoan zooplankton, the repackaging of these microorganisms into larger consumers is a fundamental step for their incorporation into pelagic food webs. Protistan consumers in the nanoplankton size range (largely flagellated protozoa ~20 um in size) play a pivotal role in plankton communities as the primary consumers of picoplankton assemblages (both bacteria and phototrophs). Yet, there is still little information on the rates of consumption of bacteria and small phytoplankton in oceanic environments, or on the growth and production rates of protistan consumers. As a part of the U.S. Joint Global Ocean Flux Study in the Arabian Sea, Dr. Caron will perform experiments to investigate the grazing rates and production of nanoplanktonic consumers from the surface waters and O2 minimum layer of this oceanic environment. The overall goal in this work is to quantify carbon flow through the first trophic interaction in the microbial plankton.