WATER MACROPHYTES AS BIO-INDICATORS OF WATER QUALITY IN THE RPPN MARAGATO STREAMS

Abstract

The pollution of water sources affects communities of living beings which may be used to assess modifications in the quality of the environment. Water macrophytes have several functions in the ecosystems, among which may be mentioned the fact that they absorb excess of nutrients and water pollutants. Current research assesses the presence, richness and frequency of water macrophytes in a stretch of the Arroio do Valinho and Arroio Pinheiro Torto and evaluates them as bio-indicators of water quality in the Reserva Particular do Patrimônio Natural Maragato in the state of Rio Grande do Sul, Brazil. Whereas no macrophyte species occurred for the stretch of Arroio do Valinho, eight species were described for the stretch of Arroio do Pinheiro Torto. Frequency was evaluated within a 200 meter transect at the streams´ meeting site where the species Tripogandra diuretica had 100% frequency, from the banks throughout the entire margin of the stretch under analysis. The bottom substrate had very high P and K rates, with Mn, Zn and Cu exceeding reference rates. Analyses of macro- and micro-nutrients in the vegetal tissue of Egeria densa (more frequent in the river bed) revealed high N, Fe, Mn and Zn rates. Current analysis complements investigation on the physical, chemical and biological parameters of water quality.