Root-associated biofilms of Eichhornia heterosperma Alexander, 1939 contribute to the remediation of the tropical reservoir Porce II,Colombia |
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| Institution: | 1. Grupo GAIA, Facultad de Ingeniería, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín, Colombia;2. Grupo GeoLimna, Facultad de Ingeniería, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín, Colombia;3. Universidad Nacional de Colombia-sede Medellín Facultad de Minas, Calle 80 # 65-223, Medellín, Colombia;4. Justus Liebig University Giessen, Institute of Animal Ecology, Heinrich Buff Ring 26, 35392 Gießen, Germany |
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| Abstract: | Two key factors were identified that enhance remediation of a hypereutrophic reservoir colonised by Eichhornia heterosperma Alexander, 1939. These factors are the high abundance of the microbial community in root-associated biofilms and their high extracellular enzyme activity (EEA). The capacity of macrophytes for nutrients removal has been widely acknowledged. However, there has been little discussion on the role of root-associated biofilms in enhancing phytoremediation. We determined nutrient levels across the reservoir quarterly during two years. We assessed the structure of the microbial community in water, root-associated biofilms, and sediments along with their phosphatase and β-glucosidase activities. We hypothesised that reservoir remediation is enhanced by increased nutrient remineralisation and bioavailability, arising from EEA in root-associated biofilms attached to E. heterosperma. Sedimentation removed 51% of the total nitrogen (TN) and 85% of the total phosphorus (TP) external load. E. heterosperma and its root-associated biofilms removed extra 8% TN and 7% TP. The abundance of the microbial community in root-associated biofilms was generally higher than in water and sediment, being dominated by Alphaproteobacteria and Betaproteobacteria. The EEA in root-associated biofilms ranged 117?1760 μmol g?1 wet weight h?1 for phosphatase and 107?676 μmol g?1 wet weight h?1 for β-glucosidase, indicating high mineralisation rates. These results showed that the microbial community in root-associated biofilms favours reservoir remediation by supplying mineralised nutrients to algae and macrophytes, but the permanent introduction of high nutrient loads exceeds the reservoir capacity for remediation. Improving the trophic state of the reservoir requires thus long-term strategies at basin scale for reducing the nutrient loads. |
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| Keywords: | Reservoir Eutrophication Nutrient loads Microbial community structure Extracellular enzyme activity |
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