Ammonium uptake and biomass interaction inCladophora glomerata(Chlorophyta)

Abstract

A relationship between algal biomass concentration and uptake of ammonium-N (NH+ 4-N) from the medium was checked in laboratory experiments. As a test organism the filamentous periphytic alga Cladophora glomerata was used. The amount of NH+ 4-N removed is not linear with increasing algal biomass, but the curves fit hyperbolae. A modified Michaelis-Menten model was used to evaluate the relationship and the uptake parameters were calculated from the linear regression analysis of the Woolf plot. The initial phase of ammonium uptake is linear, but its duration depends on the initial ammonium concentration and the algal biomass concentration. Additional irradiance causes an increase in uptake only above the algal concentration 0·2 g l-1 which supports a proposal that uptake becomes light-limited with higher algal biomass concentrations. The relationship between initial NH+ 4-N concentration and parameters of modified Michaelis-Menten equation was found to be linear. Predictions of the amounts of ammonium remov...