Dissertation Research: Bacterial Production in Lowland Rivers of the Orinoco Basin

9801092艾伦异养细菌在水生生态系统中碳和营养物质的循环中发挥着重要作用。然而，在热带淡水中，细菌活动是如何受到调控的尚不清楚。由于热带系统的温度一直很高，碳和养分供应的影响预计将特别强烈，而不是温度。此外，在热带河流，降雨量的巨大季节变化强烈地影响着陆地的碳和养分输入，这反过来又会影响细菌的活动。PI‘s有一年的初步数据显示，奥里诺科盆地低地河流的细菌产量非常低，这些数据表明与水文有关的季节性变化。在本论文的研究中，PI将调查以下问题：(1)奥里诺科盆地低地河流细菌产生的控制因素是什么？以及(2)细菌生产是否存在与水文季节性有关的模式？为了回答这些问题，PIS将进行底物添加和pH修正实验，以确定限制细菌生长的因素，并在奥里诺科盆地中部的两条布莱克河和两条清水河的年度流动周期中测量不同点处的细菌产量。这项拟议的研究将确定细菌在热带低地河流中的调节方式，并将在开发影响之前增加对新热带相对不受干扰的河流功能的了解。

9801092 Allan Heterotrophic bacteria play an important role in the cycling of carbon and nutrients in aquatic ecosystems. In tropical freshwaters, however, it is unclear how bacterial activity is regulated. Because temperatures are consistently high in tropical systems, the influence of carbon and nutrient availability, rather than temperature, is expected to be particularly strong. In addition, in tropical rivers, large seasonal variations in rainfall strongly influence the amount of carbon and nutrient inputs from land, which should in turn influence bacterial activity. The PI's have preliminary data for one year showing that bacterial production is very low in lowland rivers of the Orinoco basin, and these data suggest seasonal variation related to hydrology. In this dissertation research the PI's will investigate the following questions: (1) What is controlling bacterial production in lowland rivers of the Orinoco basin? and (2) Are there patterns in bacterial production associated with hydrologic seasonality? To answer these questions the PIs will conduct substrate addition and pH amendment experiments to determine the factors limiting bacterial growth, and measure bacterial production at different points in the annual flow cycles in two black and two clearwater rivers of the Middle Orinoco basin. The proposed research will determine how bacteria are regulated in tropical lowland rivers and will increase knowledge about the function of relatively undisturbed rivers in the neotropics before they are affected by development.