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Updated: Jul 1, 2026

Watershed Planning within a Quantitative Scenario Analysis Framework
Published on: July 24, 2016
The use of integrative tools and multiple models for aquatic environmental quality assessment: a case study of the
Josiane Araujo da Silva1, Mariana da Fountoura Martins2, Thays de Andrade Guedes2
1Instituto de Ciências Biológicas, Programa de Pós Graduação em Biologia de Ambientes Aquáticos Continentais, Universidade Federal do Rio Grande, Av, Itália Km 8, Rio Grande, RS, 96203-900, Brazil.
Abstract:
This study performed toxicity assays with microalgae, microcrustaceans, and fish as well as evaluated biochemical and behavioral biomarkers in fish and microcrustaceans to assess the quality of the surface water of Mirim Lagoon, which belongs to one of the largest hydrographic basins in the world, located in southern Brazil. Three distinct sampling periods were chosen (January, March, and June 2022) based on the rice plantation dynamics which is the main activity surrounding the lagoon. In January, the plantation is irrigated; in March, the water is drained into the Mirim Lagoon, and July is the off-season. Concerning toxicity tests, there was significant inhibition in microalgae growth when exposed to water collected in March, but no mortality was observed for Ceriodaphia dubia, Daphnia magna, and Danio rerio. Regarding biomarkers, behavioral variables contributed more to the higher values of the Integrated Biomarker Response (IBR) index for both D. magna and D. rerio, in March. The Redundancy Analysis (RDA) indicated a correlation between the biomarkers for both organisms and abiotic parameters, mainly nutrients (total phosphorus and total nitrogen), thermotolerant coliforms, total solids, and turbidity. Spatially, there was no difference during monitoring, but the most significant ecotoxicological effects were observed in March. Multivariate analysis and the IBR index proved to be useful tools for monitoring of water bodies such as Mirim Lagoon.
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