Limnetica 32
The successional phases of a periphytic algal community in a shallow tropical reservoir during the dry and rainy seasons
This study aims to describe the structural changes in a successional periphyton community during the dry and rainy seasons in a shallow tropical reservoir. The sources of structural variability of the periphytic algal community were identified on successional and seasonal scales. Glass slides were placed in macrophyte stands for periphyton colonisation over 30 d. Samples were taken at intervals of hours (24 h, 27 h, 30 h, 33 h, 45 h, 48 h, 51 h, 54 h, and 57 h) and days (3 d, 6 d, 9 d, 12 d, 15 d, 20 d, 25 d, and 30 d). The limnological conditions differed significantly between the dry and rainy seasons. The biomass increment, total density, and total biovolume increased as the colonisation time increased in both climatic periods. A CCA showed the influence of seasonal and successional scales on periphytic algal community structure. The replacement of species and structural-attribute variation furnished evidence for the occurrence of two successional phases (early and advanced) over 30 d of periphyton colonisation in both climatic periods. These successional stages were distinguished primarily by the species composition and successional trajectory. On a seasonal scale, the availability of light and nutrients were the factors that determined the organisation of the periphyton community. In conclusion, the duration of the successional phases and species trajectory during periphyton colonisation was influenced by seasonality (allogenic factors) and differential species performance (autogenic factors) in a shallow tropical reservoir.
