Effects of Eutrophication on Flagellates Associated with Eichhornia crassipes: An Experimental Approach

Abstract

AbstractThe effects of nutrient enrichment on density, biomass and on the relative contribution of pigmented and heterotrophic flagellates to the total abundance of all flagellates associated with Eichhornia crassipes were evaluated through mesocosm experiments over 33 days. Two triplicate treatments (nitrogen and phosphorus addition and a control treatment) were colonized, producing six mesocosm systems. The only variable that showed significance was flagellate density. Density increased significantly with increased nutrient concentrations in both flagellate groups, suggesting the importance of bottom‐up control mechanisms. However, the time lag and the low magnitude response to density, as well as the lack of significant variation in biomass with respect to fertilization, suggested that a complex relationship is responsible for influencing the structure of flagellate communities associated with vegetation during nutrient enrichment in these food webs. (© 2010 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)