Capture and Release of Phosphorus by Periphyton in Closed Water Systems Influenced by Illumination and Temperature

Periphyton is known to play an important role in the self-purification of aquatic ecosystems. However, little attention has been paid to the understanding of P distribution and its partitioning influenced by the physical parameters when periphyton is separated from the sediment. In this work, the effect of periphyton on the capture and release of phosphorus in closed water systems was studied and the influence of illumination and temperature conditions were investigated. Results showed that phosphorus was transferred from water to periphyton during the experiment at 15 °C, but periphyton turned from a sink to a source of phosphorus in a few days at 25 and 35 °C. Phosphorus capture in periphyton was more enhanced when illuminated at 70 than 20 μmol photons m−2 s−1 at 25 and 35 °C, but not at 15 °C. At the end of the experiment, cyanobacteria became more abundant at 25 and 35 °C and phosphorus fractionation showed that labile-P was predominant in periphyton. The release of the captured phosphorus could be related to the disaggregation of periphyton following the depletion of nutrients. Therefore, periphyton act as a temporary storage of phosphorus following nutrient input in closed water systems and the capture and release of phosphorus is strongly influenced by the environmental conditions