Aquatic invertebrates associated with the water-hyacinth (Eichhornia crassipes) in an eutrophic reservoir in tropical brazil

Quantitative samples of the aquatic invertebrate fauna associated to water- hyacinth (Eichhornia crassipes) vegetation were taken in an eutrophicated r eservoir in southeastern Brazil. The assemblage was dominated by detritivor es, most frequently oligochaetes, probably due to the large amount of sedim ent and detritus retained in the roots. Multivariate analysis (PCA and Cano nical Correlation) suggested that, while some environmental variables were important to the dynamics of the system, biological interactions with the p rosobranchiad snail Melanoides tuberculata could explain abundance patterns between sample sites.