Regulation of rivers by dams transforms previously lotic reaches above the dam into lentic ones and limits or prevents longitudinal connectivity, which impairs access to suitable habitats for the reproduction of many migratory fish species. Frequently, unregulated tributaries can provide important habitat heterogeneity to a regulated river and may mitigate the influence of impoundments on the mainstem river. We evaluated the importance of tributaries to spawning of migratory fish species over three spawning seasons, by comparing several abiotic conditions and larval fish distributions in four rivers that are tributaries to an impounded reach of the Upper Paraná River, Brazil. Our study confirmed reproduction of at least 8 long‐distance migrators, likely nine, out of a total of 19 occurring in the Upper Paraná River. Total larval densities and percentage species composition differed among tributaries, but the differences were not consistent among spawning seasons and unexpectedly were not strongly related to annual differences in temperature and hydrology. We hypothesize that under present conditions, densities of larvae of migratory species may be better related to efficiency of fish passage facilities than to temperature and hydrology. Our study indicates that adult fish are finding suitable habitat for spawning in tributaries, fish eggs are developing into larvae, and larvae are finding suitable rearing space in lagoons adjacent to the tributaries. Our findings also suggest the need for establishment of protected areas in unregulated and lightly regulated tributaries to preserve essential spawning and nursery habitats. Copyright © 2014 John Wiley & Sons, Ltd.

Information and Communications Technology in the teaching of chemistry has been a trend in the field of education, especially when the teacher aims to increase student interest and raise the quality of the classes. In this work, the PhotoMetrix PRO® app, free and available for smartphones, was used to in a colorimetry practice to measure iron by the reaction with thiocyanate. Spectrometer set at visible range is used to monitoring this reaction. At practical classes in high school, in technical and undergraduate courses the number of equipment is generally insufficient for handling by the students, and in many institutions, they are not available. The methodology was adjusted with a focus on sustainability at the chemistry laboratory, by using reduced volumes of reagents to mitigate the generation of waste and the analysis costs. The methodology presented R 2 values of 0.999, detection and quantification limits of 0.34 e 0.98 mg L-1 , respectively, and 6.0 % RSD. Iron content was measured in three samples, namely tap water, razor blade and food supplement. The level of iron was satisfactory, compared to visible-spectrophotometry results. O uso de tecnologias de informação e comunicação no ensino de química tem sido uma tendência na área da educação, em especial quando o docente tem como objetivo aumentar o interesse dos estudantes e elevar a qualidade das aulas. Neste trabalho empregou-se o aplicativo PhotoMetrix PRO®, gratuito e disponível para smartphone, em uma prática de colorimetria para determinação de íons ferro empregando tiocianato. Esta reação pode ser monitorada por espectrofotômetro na região do visível. O número destes equipamentos disponíveis para as aulas práticas no ensino médio, em cursos técnicos e de graduação são em geral insuficientes para manuseio por parte dos alunos, e em muitas instituições, não se encontram disponíveis. O método foi adaptado com enfoque na sustentabilidade em um laboratório de química, utilizando volumes reduzidos de reagentes para mitigação de resíduos e custos da análise. A metodologia apresentou valores de R 2 de 0,999, limites de detecção e quantificação de 0,34 e 0,98 mg L-1 , respectivamente, e valores inferiores a 6,0 % de DPR. Determinações de ferro foram realizadas em três amostras, água de torneira, lâmina de barbear e suplemento alimentar. Os níveis de ferro foram satisfatórios quando comparados com os resultados obtidos por espectrofotometria na região do visível.