title: Environmental factors affecting chlorophyll-a concentration in tropical floodplain lakes, Central Brazil.
abstract: Chlorophyll-a (Chl-a) has been widely used in the assessment and monitoring of aquatic environments. Local and regional factors can influence Chl-a concentrations; moreover, the connection between terrestrial and aquatic ecosystems is a major paradigm within aquatic ecology. Here, we investigate the spatial distribution of Chl-a concentrations in a tropical savannah floodplain in Central Brazil using a broad spatial data set (a 900-km north-south transect; 30 lakes). We determine the relative importance of local environmental variables (limnological and morphometric) and regional (land use) and spatial distances (spatial eigenvector) on Chl-a concentrations using partial linear regression. We evaluate the direct and indirect effects of local and regional variables on Chl-a with a path analysis. Our results indicate spatially autocorrelated patterns wherein lakes in closer proximity showed more similar levels of Chl-a than more distant lakes. Local environmental factors explained most variance in Chl-a (R2adj= 0.28; P = 0.02); more specifically, both lake area and total nitrogen significantly (P < 0.05) explained Chl-a concentrations (direct effects). Meanwhile, regional factors neither directly nor indirectly predicted Chl-a. Thus, internal processes, such as the resuspension of sediment (which is frequent in tropical floodplains), rather than external influences, were the main factors that explained Chl-a concentrations in this study. The importance of local variables in structuring Chl-a concentration may be used to guide the conservation of the aquatic ecosystems in these tropical floodplain lakes.
authors.affiliation: Universidade Estadual de Goiás, Campus de Ciências Exatas e Tecnológicas - Henrique Santillo (CCET), BR-153, no 3.105, CEP 75132-903, Anápolis, Goiás, Brazil.
authors.forename: Suzana Maria Loures
authors.initials: SM
authors.lastname: de Oliveira Marcionilio
authors.affiliation: Universidade Estadual de Goiás, Campus de Ciências Exatas e Tecnológicas - Henrique Santillo (CCET), BR-153, no 3.105, CEP 75132-903, Anápolis, Goiás, Brazil.
authors.forename: Karine Borges
authors.initials: KB
authors.lastname: Machado
authors.affiliation: Universidade Estadual de Goiás, Campus Laranjeiras, Goiânia, Goiás, Brazil.
authors.forename: Fernanda Melo
authors.initials: FM
authors.lastname: Carneiro
authors.affiliation: Universidade Federal de Goiás, Instituto de Estudos Sócio-Ambientais, Laboratório de Processamento de Imagens e Geoprocessamento, Goiânia, Goiás, Brazil.
authors.forename: Manuel Eduardo
authors.initials: ME
authors.lastname: Ferreira
authors.affiliation: Universidade Federal de Goiás, Instituto de Ciências Biológicas, Departamento de Ecologia, Goiânia, Goiás, Brazil.
authors.forename: Priscilla
authors.initials: P
authors.lastname: Carvalho
authors.affiliation: Universidade de Brasília, Planaltina, Distrito Federal, Brazil.
authors.forename: Ludgero Cardoso Galli
authors.initials: LC
authors.lastname: Vieira
authors.affiliation: Universidade Federal do Rio de Janeiro, Museu Nacional, Laboratório de Ficologia, Rio de Janeiro, Brazil.
authors.forename: Vera Lúcia
authors.initials: VL
authors.lastname: de Moraes Huszar
authors.affiliation: Universidade Estadual de Goiás, Campus de Ciências Exatas e Tecnológicas - Henrique Santillo (CCET), BR-153, no 3.105, CEP 75132-903, Anápolis, Goiás, Brazil. joao.nabout@ueg.br.
authors.forename: João Carlos
authors.initials: JC
authors.lastname: Nabout
mesh_terms: D001938:Brazil; D002734:Chlorophyll / Q000032:analysis*; D000077194:Chlorophyll A; D004784:Environmental Monitoring; D060106:Lakes / Q000737:chemistry*
chemical_list: D002734:Chlorophyll; D000077194:Chlorophyll A
keywords: Araguaia River Basin; Direct effect; Lake area; Land use; Spatial eigenvector; Total nitrogen