Aquatic macrophytes as indicators of water quality in subtropical shallow lakes, Southern Brazil Macrófitas aquáticas como indicadores da qualidade da água em pequenos lagos rasos subtropicais, Sul do Brasil

AIMS: We evaluated the potential of aquatic macrophyte communities as bioindicators in six small shallow lakes. METHODS: The sampling was conducted monthly for one year, during which all macrophytes were surveyed, and the water temperature, dissolved oxygen, pH, conductivity, total alkalinity, chlorophyll-a, suspended matter, total nitrogen (Nt) and total phosphorus (Pt) were measured. RESULTS: In total, forty-three species were recorded, and there were significant differences in the species richness and limnological conditions among the lakes studied. A canonical correspondence analysis showed that the concentration of nutrients (Nt and Pt), chlorophyll-a, suspended matter, dissolved oxygen and pH were the most important predictors of the distribution of macrophytes. Some emergents were related to the high concentration of nutrients, chlorophyll-a, and suspended matter. Moreover, the most submersed species were associated with environments with low nutrient concentrations and the lowest values chlorophyll-a and suspended matter. In addition, some species submerged and floating were related to low values pH, alkalinity and dissolved oxygen. Limnological differences between lakes may be cited as the main causes of the observed heterogeneous distribution of macrophytes. CONCLUSIONS: These results indicate the importance of limnological characteristics of the different environments in the macrophyte community composition and the potential role of this community as a bioindicator in shallow lakes in southern Brazil. OBJETIVO: Foi avaliado o potencial bioindicador da comunidade de macrófitas aquáticas em seis pequenos lagos rasos. MéTODOS: O acompanhamento foi mensal durante um ano, sendo que em cada coleta, além do registro de todas as espécies de macrófitas foram determinadas a temperatura da água, oxigênio dissolvido, pH, condutividade elétrica, alcalinidade total, clorofila-a, material em suspens o, nitrogênio total (Nt) e fósforo total (Pt). RESULTADOS: No total, quarenta e três espécies foram registradas, e ocorreram diferen as significativas na riqueza de espécies e nas condi es limnológicas entre os lagos estudados. A análise de correspondência can nica mostrou que a concentra o de nutrientes (Nt e Pt), clorofila-a, material em suspens o, oxigênio dissolvido e pH foram os mais importantes preditores da distribui o das macrófitas aquáticas. Algumas espécies emergentes estiveram relacionadas alta concentra o de nutrientes, de clorofila-a, e de material em suspens o. Por outro lado, a maioria das espécies submersas foram associadas a ambientes com b