Calidad de agua de los tributarios de la Laguna del Sauce, Maldonado, Uruguay, en base al Índice Diatomológico Pampeano (IDP)

A benthic bioindicator is applied for the first time in water quality monitoring in streams in Uruguay using diatoms. These microalgae are the most diverse group and usually constitute 80-90% of periphyton. They are recognized throughout the world for their value as indicators of eutrophication and organic pollution because they respond quickly to environmental changes and provide information on the biotic integrity of aquatic ecosystems. Thanks to these characteristics, water quality indexes have been developed based on the presence of certain species in a site. The purpose of this work was to determine which water quality is present in the tributaries of the Sauce Lagoon basin (Maldonado, Uruguay) based on the application of the Pampean Diatom index (IDP). To achieve this, the periphyton in 11 sites of five tributaries of the Sauce Lagoon System was analyzed every two months from July 2015 to December 2016. Within the 238 species determined, 44 had a relative abundance greater than 4%, and of 26 of them, information on the indicator value for the Pampean Diatom Index (Idpi) was available. According to the correspondence analysis, the species were ordered by total nitrogen, total phosphorus and phosphate. The tributaries presented poor quality of water. However, towards the lagoon drain in Represa site and Potrero stream, water quality improved and was considered as acceptable. The water quality monitoring programs could be complemented with the incorporation of this tool and it would be very useful in the assessment of the trophic state of the lotic waters.