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

小行星9801092 异养细菌在水生态系统碳和营养物质循环中起着重要作用。 然而，在热带淡水中，细菌活动是如何调节的还不清楚。 由于热带系统的温度一直很高，预计碳和养分供应的影响，而不是温度，将特别强大。 此外，在热带河流中，降雨量的季节性变化极大地影响了来自陆地的碳和养分输入量，这反过来又会影响细菌的活动。PI的一年的初步数据表明，细菌产量是非常低的低地河流的奥里诺科河流域，这些数据表明，季节性变化与水文。在本论文的研究中，PI的将调查以下问题：（1）是什么控制细菌生产在低地河流的奥里诺科河流域？和（2）是否有模式的细菌生产与水文季节性？为了回答这些问题，PI将进行底物添加和pH值修正实验，以确定限制细菌生长的因素，并测量中奥里诺科河流域两条黑水河和两条清水河年流量周期中不同点的细菌产量。拟议中的研究将确定细菌是如何在热带低地河流中受到调节的，并将增加有关新热带地区相对未受干扰的河流在受到开发影响之前的功能的知识。

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.