Variação sazonal e sucessional da comunidade de algas perifíticas em substrato natural em um reservatório mesotrófico tropical

Abstract

Colonization and succession of a periphytic algal community on a natural substrate (Nymphaea spp.) was evaluated in a shallow reservoir (Lago das Ninféias, PEFI, SP). This study aimed to evaluate the environmental factors responsible for the structural variability of a periphytic algal community. Samplings of abiotic and biological variables were carried out every three days up to the 15th day, and later at five days intervals for 30 days in the dry (4/07 to 08/03/2007) and rainy (9/01 to 02/08/2008) seasons. The petioles of Nymphaea spp. were randomly selected and cleaned. Periphytic algal structure was analyzed by measuring chlorophyll-a, algal density, biovolume, species richness and diversity. The rainy season was characterized by high temperature and nutrient availability and the dry season had the highest light availability. Periphyton biomass, algal density and biovolume were higher in the dry season than in rainy season. Different successional phases and trajectories were identified in each climatic period. Limnological conditions inside macrophyte stands changed seasonally, and consequently influenced the periphytic algal structure. The final conclusion is that the periphytic algae structure was sensitive to autogenic changes (succession), but the seasonal scale was the main source of variability in community structure.