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Comunidade ictiológica estuarina do rio Guadiana e sapal de Castro Marim
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| 5.95 MB | Adobe PDF |
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Abstract(s)
As caracteristicas dos sistemas estuarinos associadas à sua elevada produtividade biológica favorecem a colonização por parte de diversas espécies de peixes. Deste modo, este trabalho pretendeu contribuir para o conhecimento da ecologia da ictiofauna estuarina, através da identificação das diferentes categorias taxonómicas e ecológicas e na caracterização e interpretação espaciotemporal da estrutura da comunidade.
A campanha de amostragem foi realizada desde Setembro de 2000 a Agosto de 2001 em 9 locais distribuídos ao longo do medio e baixo estuário do rio Guadiana e sapal de Castro Marim.
Usaram-se duas artes distintas, uma para ser operada no sapal, a redinha, e outra no canal principal, o arrasto de portas. Durante a execução das amostragens de campo registaram-se os dados de salinidade, temperatura, profundidade e oxigénio dissolvido. No laboratório foram identificados os exemplares até ao taxon especie.
Para a compreensão da estrutura da comunidade piscicola, fez-se uma análise das
distribuição das frequências de comprimento das espécies com maior abundância e frequência relativa, e análise da distribuição da abundância e dos indices de diversidade ao longo dos locais e meses de amostragem. Para a compreensão da classificação e ordenação da comunidade usou-se a análise multivariada de acordo com o indice de Bray-Curtis e a distância euclidiana. Para melhor compreender a relação existente entre os parâmetros ambientais e abundância das espécies capturadas recorreu-se a fenologia ecológica das especies para as classificar de acordo com a sua distribuição no estuário e sapal.
The characteristics of estuaries, especially their high productivity, favour their colonisation by many species of fish. This study was carried out in order to contribute towards improving our understanding of the estuarine ichthyofauna ecology, the identification of the different taxonomic and ecological categories and the spatio-temporal interpretation of the community structure. Sampling took place from September 2000 to August 2001 in nine different sites in the middle and lower Guadiana river and salt marshes of Castro Marim. A beach seine was used in the salt marsh channels while an otter trawl was used in the main canal of the river. During the fieldwork, salinity, temperature, depth and dissolved oxygen were recorded at each sampling location. To understand the population structure of the main species, time series of length frequency distributions were constructed and analysed. The distributions of abundance and indices of diversity were analysed for each location and along the year. Multivariate analysis (cluster analysis and multidimensional scaling) based on the Bray-Curtis index and Euclidian distance was used for community classification and ordination. To better understand the relationship between environmental variables and the abundance of the species caught, fish were classified according to ecological guilds in accordance with their distribution in the estuary and sait marsh.
The characteristics of estuaries, especially their high productivity, favour their colonisation by many species of fish. This study was carried out in order to contribute towards improving our understanding of the estuarine ichthyofauna ecology, the identification of the different taxonomic and ecological categories and the spatio-temporal interpretation of the community structure. Sampling took place from September 2000 to August 2001 in nine different sites in the middle and lower Guadiana river and salt marshes of Castro Marim. A beach seine was used in the salt marsh channels while an otter trawl was used in the main canal of the river. During the fieldwork, salinity, temperature, depth and dissolved oxygen were recorded at each sampling location. To understand the population structure of the main species, time series of length frequency distributions were constructed and analysed. The distributions of abundance and indices of diversity were analysed for each location and along the year. Multivariate analysis (cluster analysis and multidimensional scaling) based on the Bray-Curtis index and Euclidian distance was used for community classification and ordination. To better understand the relationship between environmental variables and the abundance of the species caught, fish were classified according to ecological guilds in accordance with their distribution in the estuary and sait marsh.
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Keywords
Estuário do rio Guadiana Sapal de Castro Marim Peixes Distribuição espaciotemporal Abundância Indices de diversidade Análise multivariada Fenologia