title: Categorization of the trophic status of a hydroelectric power plant reservoir in the Brazilian Amazon by statistical analyses and fuzzy approaches.
abstract: The Amazon area has been increasingly suffering from anthropogenic impacts, especially due to the construction of hydroelectric power plant reservoirs. The analysis and categorization of the trophic status of these reservoirs are of interest to indicate man-made changes in the environment. In this context, the present study aimed to categorize the trophic status of a hydroelectric power plant reservoir located in the Brazilian Amazon by constructing a novel Water Quality Index (WQI) and Trophic State Index (TSI) for the reservoir using major ion concentrations and physico-chemical water parameters determined in the area and taking into account the sampling locations and the local hydrological regimes. After applying statistical analyses (factor analysis and cluster analysis) and establishing a rule base of a fuzzy system to these indicators, the results obtained by the proposed method were then compared to the generally applied Carlson and a modified Lamparelli trophic state index (TSI), specific for trophic regions. The categorization of the trophic status by the proposed fuzzy method was shown to be more reliable, since it takes into account the specificities of the study area, while the Carlson and Lamparelli TSI do not, and, thus, tend to over or underestimate the trophic status of these ecosystems. The statistical techniques proposed and applied in the present study, are, therefore, relevant in cases of environmental management and policy decision-making processes, aiding in the identification of the ecological status of water bodies. With this, it is possible to identify which factors should be further investigated and/or adjusted in order to attempt the recovery of degraded water bodies.
authors.affiliation: Universidade Federal do Pará (UFPA) Instituto de Ciências Exatas e Naturais, Faculdade de Estatística and Faculdade de Ciências da Computação, Rua Augusto Correa 01, CEP: 66075-110, Belém, PA, Brazil. Electronic address: tarcisiolobato@yahoo.com.br.
authors.forename: Tarcísio
authors.initials: T
authors.lastname: da Costa Lobato
authors.affiliation: Pontifícia Universidade Católica do Rio de Janeiro (PUC-Rio), Departamento de Química, Laboratório de Bioanalítica, Rua Marquês de São Vicente, 225 Gávea, CEP: 22453-900, Rio de Janeiro, RJ, Brazil.
authors.forename: Rachel Ann
authors.initials: RA
authors.lastname: Hauser-Davis
authors.affiliation: Universidade Federal do Pará (UFPA) Instituto de Ciências Exatas e Naturais, Faculdade de Estatística and Faculdade de Ciências da Computação, Rua Augusto Correa 01, CEP: 66075-110, Belém, PA, Brazil.
authors.forename: Terezinha Ferreira
authors.initials: TF
authors.lastname: de Oliveira
authors.affiliation: Universidade Federal do Pará (UFPA) Instituto de Ciências Exatas e Naturais, Faculdade de Estatística and Faculdade de Ciências da Computação, Rua Augusto Correa 01, CEP: 66075-110, Belém, PA, Brazil.
authors.forename: Marinalva Cardoso
authors.initials: MC
authors.lastname: Maciel
authors.affiliation: Universidade Federal do Pará (UFPA) Instituto de Ciências Exatas e Naturais, Faculdade de Estatística and Faculdade de Ciências da Computação, Rua Augusto Correa 01, CEP: 66075-110, Belém, PA, Brazil.
authors.forename: Maria Regina Madruga
authors.initials: MR
authors.lastname: Tavares
authors.affiliation: Universidade Federal do Pará (UFPA) Instituto de Ciências Exatas e Naturais, Faculdade de Estatística and Faculdade de Ciências da Computação, Rua Augusto Correa 01, CEP: 66075-110, Belém, PA, Brazil.
authors.forename: Antônio Morais
authors.initials: AM
authors.lastname: da Silveira
authors.affiliation: Centro de Tecnologia da ELETRONORTE, Rodovia Arthur Bernardes, s/n - Miramar, Telégrafo sem Fio, CEP: 66.115-000, Belém, PA, Brazil.
authors.forename: Augusto Cesar Fonseca
authors.initials: AC
authors.lastname: Saraiva
mesh_terms: D001938:Brazil; D017753:Ecosystem; D004784:Environmental Monitoring / Q000379:methods*; D005068:Eutrophication; D017143:Fuzzy Logic; D011210:Power Plants; D014874:Water Pollutants, Chemical / Q000032:analysis; D014877:Water Pollution, Chemical / Q000706:statistics & numerical data*
chemical_list: D014874:Water Pollutants, Chemical
keywords: Amazon reservoir; Environmental management; Fuzzy logic; Trophic State Index; Trophic status; Water Quality Index