The Effects of Shade and Nutrients on Standing Crop of Periphyton Communities in Artificial Streams

T In order to study the effects of shading and addition on nutrients of periphyton standing crop, we exposed periphyton communities to two levels of irradiance and three levels of nutrients in artificial streams. We observed that periphyton communities has been affected by both light levels and nutrients treatments in artificial streams. Results obtained from these experiments revealed that various aspects of the community productivity including dry mass, ash- free dry mass, chlorophyll a and biovolume have decreased in shading treatment, whereas periphyton biomass increased in unshaded treatments. Addition of N and P increased periphyton biomass in both shaded and unshaded treatments. Both light and nutrient treatments altered taxonomic structure by increasing abundance of upright diatoms such as Achnanthes in all shading treatments.

کلیدواژه ها:

Periphyton ، shade ، nutrients ، artificial streams