Environmental assessment in tropical streams by using abundance-biomass curves and W index in fish assemblages

ABSTRACT We investigated the fish fauna response to different environmental conditions of urban (three) and rural (seven) streams through biomass/abundance curves and W index of environmental stress. Negative values of W indicate some level of stress, while positive values suggest environments with lower stress. Dissolved oxygen, marginal erosion (both left and right margins), mesohabitat diversity, and percentage of canopy cover were measured to characterize the 10 streams analysed around Maringá city, Southern Brazil. Fish were sampled by electrofishing, then identified and weighed. Results showed negative values of W to the urban streams and positive to the rural. Urban streams showed a tendency to have assemblages of fish with lower biomass and greater abundance (r-strategists).