Spatial-temporal characteristics of epilithic algae succession on artificial substrata in relation to water quality in Erhai Lake, Yunnan Province, China

In this study, two sites with different nutritional levels at Erhai Lake were selected to perform an epilithic succession experiment in order to better understand the successional dynamic process and associated controlling factors, providing important insights into the role of epilithon in ecological functions and facilitating eutrophic lake recovery planning. The environmental parameters, epilithic biomass and epilithic diversity were qualitatively and quantitatively assessed. Our results showed that faster biomasses peaks (40–50 days colonization) were achieved at Gusheng where nutrient level was higher, comparing with that of Xiahe. A 10-day incubation period is a dividing line from an initial successional stage to the following stage during epilithon succession. The epilithic biomass and biodiversity exhibited distinctly spatial-temporal characteristics, showing higher values at the site being affected by human activities than that being under the natural condition. The spatial characteristic was associated with nitrate enrichment (the most important), and the positively biological responses of the epilithon (higher biomass and diversity) to nitrate enrichment highlight the occurrence of non-point-source pollution on the west bank of Erhai Lake. The temporal characteristic was associated with water temperature (the second important), exhibiting a high biomass accumulation in winter compared with that in summer. This may be caused by other biotic factors not measured in this study, therefore, a detailed investigation regarding the interactions among biotic components in Erhai Lake is essentially needed.