Longitudinal distribution and seasonality of macroalgae in a subtropical stream impacted by organic pollution
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Data
2010-06-01
Autores
Peres, Cleto Kaveski [UNESP]
Branco, Ciro Cesar Zanini [UNESP]
Krupek, Rogério Antonio [UNESP]
Rocha, José Celso [UNESP]
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Associação Brasileira de Limnologia
Resumo
OBJETIVO: O presente estudo foi desenvolvido com o objetivo de avaliar a distribuição longitudinal e temporal e o efeito da poluição orgânica em comunidades de macroalgas em um riacho subtropical; MÉTODOS: A presença e a cobertura percentual das macroalgas foram investigadas durante um período sazonal em quatro pontos de amostragem ao longo do perfil longitudinal do rio Cascavel, Estado do Paraná, região subtropical do Brasil. Os pontos de amostragem foram aleatoriamente escolhidos, porém as suas localizações em relação às fontes de poluição orgânica urbanas foram consideradas. em adição, diversas variáveis ambientais comumente relacionadas à poluição orgânica em ecossistemas aquáticos foram mensuradas; RESULTADOS: Durante as amostragens foram encontrados 11 táxons macroalgais. Chlorophyta foi a divisão predominante (4 espécies ou 36,3% da riqueza total), seguida por Cyanophyta e Rhodophyta (3 ou 27,3%) e Heterokontophyta (1 ou 9,1% do total). A Análise de variância (ANOVA) revelou que não existiram diferenças significativas nos valores de diversidade de espécies, cobertura percentual e índice de diversidade entre as estações do ano ou entre os pontos de amostragem. Além disso, a diversidade de espécies não se correlacionou com nenhuma variável ambiental em particular. Por outro lado, a composição relativa da comunidade de macroalgas mostrou ampla variação espacial e temporal. Assim, Chlorophyta registrou maiores valores de riqueza e cobertura percentual no ponto de amostragem com maior nível de poluição orgânica, enquanto Rhodophyta não foi encontrada neste segmento. Chlorophyta teve o maior valor de cobertura percentual no inverno, ao passo que Rhodophyta e Cyanophyta na primavera e no outono, respectivamente; CONCLUSÕES: de modo geral, no presente estudo as comunidades de macroalgas foram levemente influenciadas pela poluição orgânica, particularmente pelo aumento da riqueza e cobertura percentual de Chlorophyta associado com a ausência de Rhodophyta no segmento de maior nível de poluição. em adição, a análise da riqueza no perfil longitudinal mostrou que os maiores valores foram encontrados na região intermediária, estando parcialmente de acordo com o RCC (Conceito do Contínuo Fluvial).
AIM: This study was carried out to assess longitudinal and temporal distribution and the effects of organic pollution on macroalgal communities in a subtropical stream; METHODS: The occurrence and percent cover of stream macroalgae were investigated during seasonal period in four sampling sites along the course of the Cascavel Stream, in Paraná State, subtropical area of Brazil. Sampling sites were randomly chosen; however, their location in relation to urban organic pollution sources was taken into consideration. Besides, several stream variables usually related to organic pollution in aquatic ecosystems were measured; RESULTS: Eleven macroalgal taxa were found during the samplings. Chlorophyta was the prevailing division (4 species or 36.3% of the total richness), followed by Cyanophyta and Rhodophyta (3 or 27.3%) and Heterokontophyta (1 or 9.1%). Analysis of variance (ANOVA) showed no significant differences in species diversity, percent cover and diversity index among seasons or the sampling sites. In addition, species diversity was not correlated with any environmental variable in particular. on the other hand, the relative composition of the stream macroalgal communities showed wide spatial and temporal variation. Thus, Chlorophyta had higher values of richness and percent cover in sampling site with higher levels of organic pollution, while Rhodophyta was never found in this segment. Taking seasonality into consideration, Chlorophyta had higher values of percent cover in winter, but Rhodophyta and Cyanophyta in spring and fall, respectively; CONCLUSIONS: In general terms, in this study macroalgal community structures were slightly affected by organic pollution, mainly by increase in richness and percent cover of Chlorophyta associated with the absence of Rhodophyta in the most polluted sampling site. The analysis of the richness throughout the stretch of the stream showed that the highest values were found in the intermediate part, being partly in accordance with the RCC (River Continuum Concept).
AIM: This study was carried out to assess longitudinal and temporal distribution and the effects of organic pollution on macroalgal communities in a subtropical stream; METHODS: The occurrence and percent cover of stream macroalgae were investigated during seasonal period in four sampling sites along the course of the Cascavel Stream, in Paraná State, subtropical area of Brazil. Sampling sites were randomly chosen; however, their location in relation to urban organic pollution sources was taken into consideration. Besides, several stream variables usually related to organic pollution in aquatic ecosystems were measured; RESULTS: Eleven macroalgal taxa were found during the samplings. Chlorophyta was the prevailing division (4 species or 36.3% of the total richness), followed by Cyanophyta and Rhodophyta (3 or 27.3%) and Heterokontophyta (1 or 9.1%). Analysis of variance (ANOVA) showed no significant differences in species diversity, percent cover and diversity index among seasons or the sampling sites. In addition, species diversity was not correlated with any environmental variable in particular. on the other hand, the relative composition of the stream macroalgal communities showed wide spatial and temporal variation. Thus, Chlorophyta had higher values of richness and percent cover in sampling site with higher levels of organic pollution, while Rhodophyta was never found in this segment. Taking seasonality into consideration, Chlorophyta had higher values of percent cover in winter, but Rhodophyta and Cyanophyta in spring and fall, respectively; CONCLUSIONS: In general terms, in this study macroalgal community structures were slightly affected by organic pollution, mainly by increase in richness and percent cover of Chlorophyta associated with the absence of Rhodophyta in the most polluted sampling site. The analysis of the richness throughout the stretch of the stream showed that the highest values were found in the intermediate part, being partly in accordance with the RCC (River Continuum Concept).
Descrição
Palavras-chave
variação em escala local, Brasil, impacto antropogênico, avaliação ambiental, local-scale variation, Brazil, anthropic impact, environmental assessment
Como citar
Acta Limnologica Brasiliensia. Associação Brasileira de Limnologia, v. 22, n. 2, p. 199-207, 2010.