Relative Importance of the Heterotrophic Bacterivory in Oceanic Environments: Microbial Loop

海洋环境中异养细菌的相对重要性：微生物循环

• 批准号: 8901005
• 负责人: David Caron
• 金额: $ 22.26万
• 依托单位: Woods Hole Oceanographic Institution
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1989
• 资助国家: 美国
• 起止时间: 1989-06-15 至 1993-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=8901005&HistoricalAwards=false
• 关键词: Relative; Importance; Heterotrophic; Bacterivory; Oceanic

The role of pelagic microzooplankton in food webs of the sea has been explored sketchily in field work. Small, delicate organisms are difficult to isolate and study in the field situation. One method of studying their role is to compare food chains of widely different marine environments. The goal of this research program is to determine the relative importance of carbon transformation through the microbial loop of an oligotrophic and euptrophic oceanic community, including especially the consumers of bacterial biomass. The hypothesis to be tested is that a greater percentage of the total amount of carbon fixed by primary productivity is consumed and respsired by heterotrophic microorganisms, i.e. bacteria and protozoa, in oceanic ecosystems than in coastal ecosystems. Primary productivity, bacterial productivity, and bactivory will be measured at a coastal site and a Sargasso Sea site during three cruises in the western North Atlantic. The total amount of bacterial carbon produced and the percentage of primary production that this bacterial carbon represents will be determined in these oceanic environments and compared to the patterns of microbial carbon tranformation in two neritic environments, Chesapeake Bay and Vineyard Sound. Size fractionation and single cell isolation studies of common species of larger protozoa and microm;etazoa will be performed using radiolabelled natural bacteria in order to identify the primary consumers of bacterial biomass in these communities. %%% Much of the carbon produced in the sea is in the form of microorganisms too small to see or easily manipulate. In recent years it has become clear that these organisms are quite crucial to the food chain of the seas from the poles to the equator. One way to evaluate the importance of the microorganisms is to compare their growth rates in several different environments and to examine which organisms are able to feed on the microorganisms. This study will measure rates of growth of several types of microorganisms in contrasting environments, the relatively impoverished Sargasso Sea and the relatively fertile Georges Bank. It will also identify which organisms consume the bacteria. The expectation is that microbial production is much more important in the food chain of the Sargasso Sea than it is in the Georges Bank area.

中上层微型浮游动物在海洋食物网中的作用已在实地工作中得到粗略探索。 小型、脆弱的生物体很难在野外分离和研究。 研究它们作用的一种方法是比较不同海洋环境的食物链。 该研究计划的目标是确定通过寡营养和富营养海洋群落的微生物循环（特别包括细菌生物质的消费者）碳转化的相对重要性。 要检验的假设是，在海洋生态系统中，初级生产力固定的碳总量中，有更大比例被异养微生物（即细菌和原生动物）消耗和呼吸，而不是在沿海生态系统中。 在北大西洋西部的三次航行期间，将在沿海地点和马尾藻海地点测量初级生产力、细菌生产力和细菌活性。 所产生的细菌碳总量以及该细菌碳所代表的初级生产力的百分比将在这些海洋环境中确定，并与切萨皮克湾和葡萄园湾这两个浅海环境中微生物碳转化的模式进行比较。 将使用放射性标记的天然细菌对较大原生动物和微小动物的常见物种进行尺寸分级和单细胞分离研究，以确定这些群落中细菌生物量的主要消费者。 %%% 海洋中产生的大部分碳是以微生物的形式存在的，它们太小而无法看到或容易操纵。 近年来，人们已经清楚这些生物体对于从两极到赤道的海洋食物链至关重要。 评估微生物重要性的一种方法是比较它们在几种不同环境中的生长速率，并检查哪些生物体能够以微生物为食。 这项研究将测量几种微生物在对比环境（相对贫瘠的马尾藻海和相对肥沃的乔治浅滩）中的生长速率。 它还将识别哪些生物体消耗了细菌。 预计微生物生产在马尾藻海的食物链中比在乔治浅滩地区重要得多。