Influence of land use and occupation on water quality and on the diatom community of reservoirs in northeast Brazil

Historically, the reduction in water quality has been associated with changes in land use, especially changes in urbanization and expansion of agricultural frontiers. The objective of this study was to understand the characteristics of the diatomological community and the use and occupation of the soil around three reservoirs (Arara, Rio do Canto and Araçagi) and natural lagoon (Lagoa do Paó) (Northeast Brazil). Land use was determined using high spatial resolution satellite images. Abiotic variables of water and total phosphorus, organic matter and diatoms in surface sediments were analyzed. Abiotic variables and assemblages of diatoms were analyzed using Principal Component Analysis (PCA). Four types of land use have been identified, associated with anthropogenic change and intensive use of the landscape. The PCA separated the reservoirs by trophic status based on the total phosphorus in the water. 24 taxa of diatoms distributed in 12 genera and 10 families were identified in the sediment. Our results indicate the occurrence of planktonic, epiphytic and benthic diatoms adapted to different trophic gradients