OBJETIVOS: Este estudo visou testar experimentalmente a influência de um peixe planctófago filtrador (Tilapia rendalli) sobre a dinâmica fitoplanctônica de um reservatório tropical pequeno e raso (Lago Monte Alegre, Brasil). Adultos de T. rendalli deste lago alimentam-se preferencialmente de fitoplâncton e nossas hipóteses são: I) adultos de T. rendalli reduziriam a biomassa e composição do fitoplâncton através da herbivoria direta, e II) como este é um sistema eutrófico, o peixe poderia não ter grande influência sobre o fitoplâncton através da ciclagem de nutrientes. MÉTODOS: para avaliar esses diferentes efeitos sobre as algas, um experimento de campo foi feito no período de verão durante 15 dias em mesocosmos isolados do sedimento, usando um grupo controle (sem peixe) e um grupo tratamento (com um peixe em cada mesocosmo). As variáveis físicas e químicas e o fito- e zooplâncton foram avaliados no início, meio e fim do experimento. RESULTADOS: No final do experimento, foi observado um incremento significativo nas concentrações de íon amônio, biomassa fitoplanctônica total, de cianobactérias e zignemafíceas e de todas as classes de tamanho, exceto a classe II (20-30 µm) no grupo tratamento (com peixe). Foi observado o incremento da biomassa de uma cianobactéria potencialmente tóxica (Cylindrospermopsis raciborskii) no tratamento com peixe, no final do período experimental. CONCLUSÃO: Este estudo não deu suporte às duas hipóteses iniciais. Ele suporta a afirmação de que em corpos de água tropicais, com características semelhantes ao ambiente estudado, peixes planctófagos filtradores, como T. rendalli, não são efetivos na redução da biomassa fitoplanctônica através da herbivoria direta, mesmo sendo o fitoplâncton um dos seus principais itens alimentares. T. rendalli pode contribuir para o incremento da biomassa fitoplanctônica e pode promover ou incrementar a eutrofização de sistemas aquáticos.

AIM: This study aimed to experimentally test the influence of a planktivorous filter-feeding fish (Tilapia rendalli) on the phytoplankton dynamics of a small and shallow tropical reservoir (Lake Monte Alegre, Brazil). Adults of T. rendalli of this lake feed preferentially on phytoplankton, and we hypothesize that: I) adults of T. rendalli will decrease the phytoplankton biomass and composition through direct herbivory, and II) as it is a eutrophic system, fish would not have strong influence on phytoplankton through nutrient cycling. METHODS: To evaluate these different effects on algae, a field experiment was performed in the summer period for 15 days, in mesocosms isolated from the sediment, using a control group (no fish) and a treatment group (with one fish in each mesocosm). Physical and chemical variables and phyto- and zooplankton were evaluated at the start, middle, and end of the experiment. RESULTS: At the end of the experiment, it was observed a significant increase in ammonium concentrations and total phytoplankton biomass, Cyanobacteria and Zygnemaphyceae and all size classes except class II (20-30 µm) in the treatment group (with fish). The biomass increase of the potentially toxic cyanobacterium Cylindrospermospsis raciborskii was also observed in the fish treatment at the end of the experimental period. CONCLUSION: This study did not support both initial hypotheses. It supports the assertion that in tropical water bodies, with similar characteristics to the environment studied, planktivorous filter-feeding fish, such as T. rendalli, are not effective in reducing phytoplankton biomass through direct grazing, even when phytoplankton is one of their main food items. T. rendalli can contribute to the increase of phytoplankton biomass and can promote or increase the eutrophication of aquatic systems.

Introduction. Depressive symptoms in health sciences students are common, these might be potentially detrimental. Objectives. To determine the prevalence of depressive symptoms and its associated factors in students from the Health Sciences Faculty of the Universidad Peruana de Ciencias Aplicadas in Lima (Peru), June 2010. Materials and methods. Cross-sectional analytic study; a pre-consented survey was applied to the population 590/869 students. Zung’s abbreviated scale was used to measure depressive symptoms. To evaluate de associated factors, logistic regression was used, p<0.05 was considered statistically significant. Results. The mean age was 18.97 ± 2.45 years and 71.1% were women, 19.6% were migrants and 62.5% were medical students. The prevalence of depressive symptoms was 31.2% in the whole population and in medical students was 33.6%. Depressive symptoms were not associated in bivariate analysis with sex, career, having failed a course, living alone or being a migrant (p>0.05). In the multivariate analysis, significant statistical association was found between depressive symptoms and dissatisfaction with the own academic performance (OR=2.13 CI95%1.47-3.08), dissatisfaction with the current economic status (OR=1.93 CI95%1.24-2.99) and living with a relative external to the nuclear family (OR=1.62 CI95%1.07-2.45). Conclusion. A high prevalence of depressive symptoms was found, especially in medical students; being dissatisfaction with academic performance, economic status and living with a relative external to the nuclear family associated factors that could be taken into account in order to build preventive programs.

Introducción. Los síntomas depresivos en estudiantes de ciencias de la salud son comunes y podrían ser potencialmente perjudiciales. Objetivos. Determinar la prevalencia de síntomas depresivos y sus factores asociados en los estudiantes de la Facultad de Ciencias de la Salud de la Universidad Peruana de Ciencias Aplicadas, Lima (Perú), junio 2010. Materiales y métodos. Estudio analítico transversal; se realizó una encuesta previo consentimiento informado a 590/869 estudiantes. Para medir la variable de respuesta (síntomas depresivos) se usó la escala de Zung abreviada. Se empleó la regresión logística múltiple para evaluar los factores asociados, considerando un nivel de significancia de p<0,05. Resultados. La edad media fue 18,97 ± 2,45 años; 71,1% fueron mujeres; 19,6% fueron migrantes y 62,5% fueron de la carrera de medicina. La prevalencia de síntomas depresivos fue 31,2% en la población y de 33,6% en estudiantes de medicina. No se encontró asociación en el análisis bivariado con el sexo, carrera de estudio, si ha repetido cursos, si vive solo o si es migrante (p>0,05). En el análisis multivariado, se encontró asociación con la inconformidad de su rendimiento académico (OR=2,13; IC95%:1,47-3,08), inconformidad con la situación económica actual (OR=1,93; IC95%:1,24-2,99) y vivir con un familiar externo a la familia nuclear (OR=1,62; IC95%:1,07-2,45). Conclusión. Existe una alta prevalencia de síntomas depresivos en la población estudiada, especialmente en los alumnos de la carrera de medicina, siendo la inconformidad con el rendimiento académico, con su economía y vivir con un familiar externo a la familia nuclear, factores asociados que podrían tomarse en cuenta para trabajar programas preventivos.

Introduction. Depressive symptoms in health sciences students are common, these might be potentially detrimental. Objectives. To determine the prevalence of depressive symptoms and its associated factors in students from the Health Sciences Faculty of the Universidad Peruana de Ciencias Aplicadas in Lima (Peru), June 2010. Materials and methods. Cross-sectional analytic study; a pre-consented survey was applied to the population 590/869 students. Zung’s abbreviated scale was used to measure depressive symptoms. To evaluate de associated factors, logistic regression was used, p<0.05 was considered statistically significant. Results. The mean age was 18.97 ± 2.45 years and 71.1% were women, 19.6% were migrants and 62.5% were medical students. The prevalence of depressive symptoms was 31.2% in the whole population and in medical students was 33.6%. Depressive symptoms were not associated in bivariate analysis with sex, career, having failed a course, living alone or being a migrant (p>0.05). In the multivariate analysis, significant statistical association was found between depressive symptoms and dissatisfaction with the own academic performance (OR=2.13 CI95%1.47-3.08), dissatisfaction with the current economic status (OR=1.93 CI95%1.24-2.99) and living with a relative external to the nuclear family (OR=1.62 CI95%1.07-2.45). Conclusion. A high prevalence of depressive symptoms was found, especially in medical students; being dissatisfaction with academic performance, economic status and living with a relative external to the nuclear family associated factors that could be taken into account in order to build preventive programs.

Introducción. Los síntomas depresivos en estudiantes de ciencias de la salud son comunes y podrían ser potencialmente perjudiciales. Objetivos. Determinar la prevalencia de síntomas depresivos y sus factores asociados en los estudiantes de la Facultad de Ciencias de la Salud de la Universidad Peruana de Ciencias Aplicadas, Lima (Perú), junio 2010. Materiales y métodos. Estudio analítico transversal; se realizó una encuesta previo consentimiento informado a 590/869 estudiantes. Para medir la variable de respuesta (síntomas depresivos) se usó la escala de Zung abreviada. Se empleó la regresión logística múltiple para evaluar los factores asociados, considerando un nivel de significancia de p<0,05. Resultados. La edad media fue 18,97 ± 2,45 años; 71,1% fueron mujeres; 19,6% fueron migrantes y 62,5% fueron de la carrera de medicina. La prevalencia de síntomas depresivos fue 31,2% en la población y de 33,6% en estudiantes de medicina. No se encontró asociación en el análisis bivariado con el sexo, carrera de estudio, si ha repetido cursos, si vive solo o si es migrante (p>0,05). En el análisis multivariado, se encontró asociación con la inconformidad de su rendimiento académico (OR=2,13; IC95%:1,47-3,08), inconformidad con la situación económica actual (OR=1,93; IC95%:1,24-2,99) y vivir con un familiar externo a la familia nuclear (OR=1,62; IC95%:1,07-2,45). Conclusión. Existe una alta prevalencia de síntomas depresivos en la población estudiada, especialmente en los alumnos de la carrera de medicina, siendo la inconformidad con el rendimiento académico, con su economía y vivir con un familiar externo a la familia nuclear, factores asociados que podrían tomarse en cuenta para trabajar programas preventivos.