Diel variation of aquatic insect drift in streams of Southern Brazil

Some organisms, such as aquatic insects, are transported from the upstream to downstream region of streams through a process called drift. This process occurs in passive and active ways and can be variable throughout the day, mainly between the nocturnal and diurnal periods. Here, we evaluate the periodicity of the drift of aquatic insects in two streams of the Middle Iguaçu basin, southern region of Brazil. We predicted that the drift of aquatic insects brings the highest richness, diversity and abundance during the nocturnal period, compared to the diurnal period. In addition, we expected that the composition of species is different between these periods. In each stream, aquatic insect sampling was carried out 10 times, for 24 hours, using drift nets. A total of 2,114 aquatic insect specimens were recorded, distributed in 26 families. Of these families, 20 were recorded during the diurnal period and 24 during the nocturnal period. Our results showed an increase in the diversity and abundance of aquatic insect drift in the nocturnal period. However, only abundance was significantly different between the periods. We attribute the higher abundance in nocturnal drift possibly to biological interactions. Thus, nocturnal drift can be a strategy of some aquatic insects to avoid visual predation by other invertebrates and/or vertebrates, in Neotropical streams. We highlight the importance of our study, because it can be used for comparison in surveys of lotic environments that have been impacted by human activity (e.g. by dam construction), which can alter the water flow, and consequently the pattern of insect drift.

Colonization of benthic invertebrates on artificial and natural substrate in a Neotropical lotic environment in Southern Brazil

The objective of this research was to validate the colonization process on natural and artificial substrates by benthic invertebrates in a tropical stream in South Brazil. The samples were performed in July and August-2012, and 32 samplers were used, being 16 natural and 16 artificial substrates. In each sample, two replicas were taken for each substrate at the 2th, 4th, 7th, 14th, 21th28th, 35th and 42thdays of colonization. The organisms were identified to the lowest possible taxonomic level. In both substrates 3,070 benthic invertebrates were detected, of which 1,753 individuals were collected on the natural substrate, and 1,317 on the artificial substrate. From the identified taxa 8.5% were not dominant (Anacroneuria, Orthocladiinae, Tupiara, Smicridea, Baetodes, Tupiperla, Macrogynoplax, Gripopteryx, Cylloepus, Macrelmis, Microcylloepus, Hetaerina, Argia, Coryphaeschna, Atopsyche, Pomacea, Corydalus, Leptohyphes and Eccoptura), and31.5% were dominant (Tanypodinae, Chironominae, and Paragripopteryx). The genus Simulium was very common, dominant and abundant, representing 65% of the collected individuals. No significant difference was found in the abundance and species composition between artificial and natural substrates. On the natural substrate, the higher colonization index was at the 35th day with 459 individuals, and the lowest was at the 14th day, with 87. On the artificial substrate the highest index was at the 42thday with 337 individuals, and the lowest was at the 4th day, with 85. Both natural and artificial substrates are efficient in characterizing the benthic community. In the evaluation of the ecological succession, it was not possible to observe a pattern that described the process, since the composition was nearly constant throughout the study period.

Comparison of nuclear abnormalities in Astyanax bifasciatus Cuvier, 1819 (Teleostei: Characidae) of two sections of rivers from the middle Iguaçu / Comparação de anormalidades nucleares em Astyanax bifasciatus Cuvier, 1819 (Teleostei: Characidae) de dois trechos de rios do médio Iguaçu

Most changes in water bodies are result of human activities that have the potential to undermine the environmental integrity of aquatic ecosystems. Changes in genetic material can be evidenced by the frequency of nuclear abnormalities in fish blood cells, in response to genotoxic agents even at low concentrations. Thus, we aimed at comparing the frequencies of nuclear abnormalities of fish kept in acclimation, with fish collected in Timbó river (Santa Cruz do Timbó, Santa Catarina State), under low anthropogenic interference, and fish collected in Iguaçu river (União da Vitória, Paraná State), a polluted river. The highest frequency of changes in nuclear morphology of fish erythrocytes was found in the urbanized area around the Iguaçu river, while, the fish collected in areas with preserved riparian forest surrounding the Timbó river and acclimated fish showed no morphological changes. Our results suggest that genotoxic compounds in the Iguaçu river are acting as stressors to aquatic communities, especially fish. In addition, the absence of nuclear abnormalities in fish from the Timbó river suggests that rivers without significant environmental changes can serve as reference point for comparative studies of genetic modifications for the species studied.

A maioria das alterações dos corpos hídricos é resultante das atividades antrópicas que são prejudiciais à integridade ambiental dos ecossistemas aquáticos. Alterações no material genético podem ser evidenciadas pela frequência de anormalidades nucleares em peixes, em resposta a agentes genotóxicos, mesmo em baixas concentrações. Dessa forma, o estudo consistiu em comparar as frequências de anormalidades nucleares de peixes mantidos em aclimatação, com peixes coletados no rio Timbó (Santa Cruz do Timbó, Estado de Santa Catarina), local com pouca interferência antropogênica e, peixes coletados no rio Iguaçu (União da Vitória, Estado do Paraná), um rio poluído. As maiores frequências de alterações na morfologia nuclear dos eritrócitos dos peixes foram visualizadas na área urbanizada ao redor do rio Iguaçu, quando comparados com os peixes coletados em área com mata ciliar preservada, no rio Timbó, e os peixes aclimatados, que não apresentaram alterações morfológicas. Esses resultados sugerem que há compostos genotóxicos no trecho médio do rio Iguaçu que são estressores para os peixes. Além disso, a não observação de anormalidades nucleares no rio Timbó sugere que rios sem alterações ambientais podem servir como ponto de referência para estudos comparativos de modificações genéticas para a espécie estudada.

Análise dos registros de usuários do programa hiperdia / Analysis of the records of users of the 'hiperdia' program / Análisis de los registros de usuarios del programa hiperdia

Estudo de cunho documental, epidemiológico descritivo, teve por objetivo avaliar a efetividade dos registros das fichas de cadastro de usuários do Sistema de Cadastramento e Acompanhamento de Hipertensos e Diabéticos - HIPERDIA de um município do Rio Grande do Sul-Brasil. Os dados relativos a 637 cadastros de 17 micro áreas foram compilados, no período de agosto de 2010 a dezembro de 2011 e analisados por meio do programa BIOESTAT® versão 4.0. Destaca-se entre os resultados maior prevalência de hipertensos; tabagismo, sedentarismo e sobrepeso/obesidade como fatores de risco; infarto agudo do miocárdio, acidente vascular cerebral e doença renal como complicações das doenças. O expressivo não preenchimento de campos obrigatórios e de interesse epidemiológico pode prejudicar melhor caracterização dos usuários e o planejamento de ações de prevenção e reorganização dos serviços de saúde.

This documental, descriptive and epidemiological study aimed to evaluate the quality of the record taking in the registration forms of users of the Hypertensives and Diabetics Registration and Monitoring System (known in Portuguese as HIPERDIA) in a municipality in the state of Rio Grande do Sul (RS), Brazil. The data relating to 637 records from 17 micro-areas were compiled, for the period August 2010 - December 2011 and were analyzed using the BIOESTAT® program, version 4.0. Among the results, the following stand out: higher prevalence of hypertensives; smoking, sedentarism and overweight/obesity as risk factors; and acute myocardial infarction, cerebrovascular accidents and kidney disease as complications of the diseases. The significant failure to fill out areas which are obligatory and of epidemiological interest may hinder better characterization of the service users and the planning of preventive actions and reorganization of the health services.

Estudio documental, epidemiológico descriptivo, que tuvo por objetivo evaluar la efectividad de los registros de fichas de usuarios del Sistema de Registro y Acompañamiento de Hipertensos y Diabéticos - HIPERDIA de un municipio del Rio Grande do Sul, Brasil. Los datos referentes a 637 registros de 17 micro áreas fueron compilados en el periodo de agosto de 2010 a diciembre de 2011 y analizados por medio del programa BIOESTAT® versión 4.0. Se destaca, entre los resultados, mayor prevalencia de hipertensos; tabaquismo, sedentarismo y sobrepeso/obesidad como factores de riesgo; infarto agudo del miocárdio, accidente vascular cerebral y enfermedad renal como complicaciones de las enfermedades. El expresivo no relleno de campos obligatorios y de interés epidemiológico puede perjudicar una buena caracterización de los usuarios y el planeamiento de acciones de prevención y reorganización de los servicios de salud.