A Test of the Dependence of Secondary Production on Unicellular Algae in Running Water Ecosystems

9318205刘易斯对盐沼、海草群落和泛滥平原的研究表明，水生生态系统的消费食物网可能强烈依赖单细胞藻类的生产，即使维管植物的有机质丰富。这些发现表明，单细胞藻类在支持自来水中的消费者生物量方面的相对重要性可能被低估了，自来水往往以维管植物的有机物为主。该提案概述了一项计划，将在科罗拉多州落基山脉的两条河流的大坡度物理条件下测试这一概念。该研究计划基于稳定同位素方法学的应用，这一点已经通过在拟议的野外地点进行的试点研究表明，能够很好地区分维管植物碳和藻类碳。工作假设是，只要物理条件允许基质中有足够的光照来支持藻类的生长，藻类碳对次生生产的总体贡献就很高。其中包括对次生生产的必然测量，以便能够量化藻类碳对消费生产的相对贡献。这项研究将阐明藻类碳在各种物理条件下的相对重要性，以及维管植物有机碳的存在。

9318205 Lewis Studies of salt marshes, seagrass communities, and flood plains have shown that the consumer food webs of aquatic ecosystems may be strongly dependent on production of unicellular algae, even when organic matter from vascular plants is abundant. These findings suggest that the relative importance of unicellular algae in supporting consumer biomass in running waters, which are often dominated by organic matter from vascular plants, may have been underestimated. The proposal outlines a plan for testing this concept over a broad gradient of physical conditions in two rivers of the Colorado Rockies. The study plan is based on the application of stable isotope mentodology, which has been shown by means of pilot studies on the proposed field sites to provide good discrimination between vascular plant carbon and algal-derived carbon. The working hypotheses is that the overall contribution of algal carbon to secondary production is high whenever physical conditions permit sufficient irradiance at the substrate to support algal growth. The drainage basins, and includes corollary measurements of secondary production so that relative contributions of algal carbon to consumer production can be quantified. The study will clarify the relative importance of algal carbon over a wide range of physical conditions in the presence of organic carbon derived from vascular plants.