REU/ROW: Factors Controlling Algal Periphyton Growth and Nitrogen Transformations in a Lowland Tropical Stream

哥斯达黎加东部山坡上的一片热带雨林 从大西洋沿岸平原的近海平面延伸到 2，600米在中央科迪勒拉的火山峰。 这 陆地走廊构成了最后一个完整的 位于中环的热带雨林 美国的大西洋斜坡，提供了一个无与伦比的网站， 对原始热带溪流的调查。 以前的研究 这表明，富含磷的溪流在 这个连续体的下端是氮的重要部位 通过微生物反硝化作用进行转化。 微量元素 藻类生长的限制也已得到证实。 本研究的重点是控制藻类生产的因素 和氮的转化在一个低地沼泽森林流。 它将促进我们对地球化学循环的理解， 中美洲热带和影响藻类的众多因素 初级生产。 主要目标是：（1）测量 营养水平的季节变化和 在选定的河流河段内， （2）研究了营养元素对植物生长的影响 增加，光和鱼类放牧对藻类生长和初级 沼泽地上、下不同养分状况下的生产力 森林;（3）测量季节性波动， 内源性和营养盐条件下水系沉积物的潜力 丰富的条件下，内部，上面，下面的沼泽森林。

A transect of rainforest on Costa Rica's eastern slope extends from near sea level on the Atlantic coastal plain to 2,600 m in the volcanic peaks of the Central Cordillera. This land corridor constitutes the last intact tract of primary rainforest spanning such elevational extremes left on Central America's Atlantic Slope, providing an unparalleled site for the investigation of pristine tropical streams. Previous studies suggest that phosphorus-rich streams draining swamp forest at the lower end of this continuum are important sites of nitrogen transformation via microbial denitrification. Micronutrient limitation of algal growth has also been demonstrated. This study focuses on factors controlling algal production and nitrogen transformations in a lowland swamp forest stream. It will advance our understanding of biogeochemical cycles in the Central American tropics and the numerous factors affecting algal primary production. Major objectives are: (1) to measure seasonal variation in nutrient levels and diurnal variations in nutrient flux in selected stream reaches located within, above and below swamp forest; (2) to examine effects of nutrient additions, light and fish grazing on algal growth and primary production under different nutrient regimes above and below swamp forest; and (3) to measure seasonal fluctuations in denitrifying potentials of stream sediments under endogenous and nutrient- enriched conditions, within, above, and below swamp forest.