Taxonomic and functional turnover of Amazonian stream fish assemblages is determined by deforestation history and environmental variables at multiple scales

High rates of deforestation, either in the past or the present, affect many of the ecological processes in streams. Integrating deforestation history and the current landscape structure enhances the evaluation of ecological effects of land-use change. This is especially true when contemporary landscape conditions are similar but the temporal path to those conditions differs. One approach that has shown promise for evaluating biodiversity responses over time and space is the β-diversity partitioning, which combines taxonomic and functional trait-based approaches. We tested hypotheses related to stream fish assemblages' turnover in watersheds with different environmental conditions and deforestation histories. We sampled fish from 75 watersheds in the Machado River basin, Brazil, and environmental factors were quantified at multiple scales. Taxonomic turnover was higher than expected by chance, whereas functional turnover was lower than expected by the observed taxonomic turnover, indicating that deterministic processes are structuring these assemblages. The turnover, and the environmental factors differed among watersheds with different deforestation histories. Besides being scale-dependent, turnover patterns are also likely dependent on land use dynamics and involve time-lags.(AU)

Altas taxas de desmatamento, seja no passado ou no presente, afetam muitos processos ecológicos em riachos. Integrar o histórico do desmatamento à estrutura atual da paisagem melhora a avaliação dos efeitos ecológicos da mudança do uso do solo. Isto é especialmente verdadeiro quando as condições da paisagem contemporânea são semelhantes, mas seguiram trajetórias distintas. Uma abordagem promissora para avaliar as respostas da biodiversidade ao longo do tempo e espaço é a partição da diversidade-β, que combina abordagens taxonômica e funcional. Testamos hipóteses relacionadas à substituição das assembleias de peixes de riachos em microbacias com diferentes condições ambientais e histórias de desmatamento. Amostramos 75 microbacias na bacia do rio Machado, fatores ambientais foram quantificados em múltiplas escalas. A substituição taxonômica foi maior do que esperada pelo acaso, enquanto a substituição funcional foi menor do que o esperado pela substituição taxonômica, indicando que as assembleias são estruturadas por processos determinísticos. As substituições e fatores ambientais diferiram entre microbacias com históricos de desmatamento distintos. Além de serem escala-dependentes, os padrões de substituição provavelmente são dependentes da dinâmica do uso do solo, envolvendo defasagem temporal.(AU)

Geographic information system and multilevel analysis: gingival status among 12-year-old schoolchildren in São Paulo, Brazil / Sistema de información geográfica y análisis de niveles múltiples: estado gingival en escolares de 12 años de edad en São Paulo, Brasil

OBJECTIVE: To evaluate gingival and calculus status among schoolchildren 12 years of age using a geographic information system and multilevel analysis. METHODS: A total of 1 002 schoolchildren were selected from 18 municipal districts by means of cluster sampling, from among 25 public and private schools in Piracicaba, São Paulo, Brazil, in 2005. Examinations were carried out by a single calibrated examiner utilizing the criteria of the World Health Organization, as well as the Community Periodontal Index. Social, economic, and behavioral variables were recorded with the use of a questionnaire and were used in the individual analysis (first level). The variables "percentage of heads of families without income" and "percentage of illiterate heads of families" were used in the contextual analysis (second level). RESULTS: A geographic information system was constructed for mapping the distribution of gingival bleeding. The variables were visually distinguished in the maps and demonstrated a tendency toward better gingival health in the central areas of the city, which are recognized as more privileged. On the contextual level, only the "percentage of illiterate heads of families" was significantly associated to gingival bleeding. CONCLUSIONS: The study confirms better oral health status among schoolchildren from privileged families, but does not confirm the data regarding "income." The individuals from areas in which the heads of family did not have income were not associated to a higher prevalence of gingival problems. This suggests that these individuals are reasonably protected from the impact of social privation due to the actions of public health care services in the municipality.

OBJETIVO: Evaluar el estado gingival y la presencia de sarro en escolares de 12 años de edad mediante el empleo de un sistema de información geográfica y análisis de niveles múltiples. MÉTODOS: En el año 2005, se seleccionó a un total de 1 002 escolares de 18 distritos municipales mediante muestreo por grupos, con la participación de 25 escuelas públicas y privadas de Piracicaba, en el estado de São Paulo, Brasil. Un único examinador calibrado, que utilizó los criterios de la Organización Mundial de la Salud, así como el Índice Periodontal Comunitario, llevó a cabo los exámenes. Mediante un cuestionario, se registraron las variables sociales, económicas y conductuales, y estas se emplearon en el análisis individual (primer nivel). En el análisis contextual (segundo nivel), se utilizaron las variables "porcentaje de cabezas de familia sin ingresos" y "porcentaje de cabezas de familia analfabetas". RESULTADOS: Se construyó un sistema de información geográfica para elaborar mapas de la distribución de la hemorragia gingival. Los mapas, donde se pueden distinguir visualmente las variables, demostraron una tendencia hacia una mejor salud gingival en las zonas del centro de la ciudad, consideradas como privilegiadas. En el nivel contextual, únicamente el "porcentaje de cabezas de familia analfabetas" se asoció significativamente con el sangrado gingival. CONCLUSIONES: El presente estudio confirma una mejor salud bucodental en los escolares pertenecientes a familias privilegiadas, pero no confirma los datos en cuanto a "ingresos". Las personas residentes en zonas donde las cabezas de familia no tenían ingresos no presentaron una mayor prevalencia de problemas gingivales. Esto indica que estas personas, como consecuencia de las actividades de los servicios de atención de salud pública del municipio, están razonablemente protegidas de la repercusión de la privación social.