As compared to their temperate counterparts, few toxicity tests have been conducted so far into the evaluation of the sensitivity of indigenous tropical species to pesticides. Especially mixture toxicity assessments appear to be scarce. To contribute to increase our knowledge in this arena, we evaluated the acute toxicity of diuron and carbofuran and their mixtures to the neotropical oligochaetes Allonais inaequalis and Dero furcatus, and the ostracod Strandesia trispinosa. Tests were performed with both the pure active ingredients, as well as their formulated products. The toxicity of the latter to the three test organisms was generally greater than that of the pure active ingredients, although absolute differences were rather small. The sensitivity of the indigenous species was slightly greater than temperate test species from the same taxonomic groups. The concentration addition conceptual model best described the results of the mixture toxicity data. Derived deviations of this model appeared to be dependent on the test organism and as to whether the pesticides were applied as active ingredients or their commercial products. Reported field concentrations of the two pesticides indicate risks to freshwater biota, especially if they are both present. The test species used in the present study are concluded to be suitable candidates as surrogate test organisms in local pesticide risk evaluations.

Eutrophication is a process characterized by an increase in the aquatic system productivity, which causes profound changes in the structure of its communities. Owing to the high environmental sensitivity of planktonic species, the study of their communities can indicate the deterioration of the environment. The Jaguari and Jacareí reservoirs are part of the Cantareira System, supplying water to Sã o Paulo inhabitants and that has been affected by several forms of continuous human interference.Here we analyze some properties of the zooplankton community as bioindicators of eutrophication and water quality change. In situ physical and chemical measurements were carried out, water was collected for analysis and quantitative zooplankton samples were taken at eight sites in the two reservoirs, in both seasons, dry and rainy. Species were identified and their numerical abundances and biomasses were determined and used to estimate two biological indices. The overall trophic state and zooplankton structure, the Calanoida/Cyclopoida ratio and the k-dominance curves were associated with the disturbance levels, mainly represented by nutrient river inputs and by water level fluctuations. The Jaguari Reservoir was more eutrophicated than the Jacareí Reservoir, as evidenced by the obtained indices values. The zooplankton community properties used as indicators of the reservoir trophic state were useful monitoring tools. Keywords: zooplankton, ABC curves, Calanoida/Cyclopoida ratio, Cantareira System, environmental impact.GAZONATO NETO, A.J., SILVA, L.C., SAGGIO, A.A., ROCHA, O Comunidades zooplanctônicas como bioindicadoras de eutrofização em reservatórios tropicais.http://dx.doi. org/10.1590/1676-06032014001814Resumo: A eutrofização é um processo caracterizado pelo aumento da produtividade do sistema aquá tico, o que provoca profundas alteraçõ es na estrutura de suas comunidades. Devido à alta sensibilidade ambiental das espécies planctô nicas, o estudo de suas comunidades pode indicar a deterioraçã o do ambiente. Os reservató rios Jaguari e Jacareí sã o parte do Sistema Cantareira, que fornece á gua para os habitantes de Sã o Paulo e que tem sido afetado por diversas formas de contínua interferência humana. Neste trabalho vamos analisar algumas propriedades da comunidade zooplanctô nica como bioindicadoras de eutrofizaçã o e alteraçã o da qualidade da á gua. Foram realizadas mediçõ es in situ de variá veis físicas e químicas, amostras de á gua foram coletadas para aná lises e amostras quantitativas de zooplâ ncton foram coletadas em oito localidades compreendendo os dois reservató rios, em duas estaçõ es, seca e chuvosa. As espécies foram identificadas e suas abundâ ncias numéricas e biomassas foram determinadas e utilizadas para estimar dois índices bioló gicos. O estado tró fico e a estrututa do zooplâ ncton, a relaçã o Calanoida / Cyclopoida e as curvas de k-dominâ ncia foram associados com os níveis de perturbaçã o, representada principalmente pela entrada de nutrientes transportados pelo rio e pelas flutuaçõ ...

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