RESUMO
Seasonal dynamics of macroalgal communities was analyzed monthly by samplings in three stream segments of the Pedras River Basin, mid-south region of Paraná State, southern Brazil, from April 2004 to March 2005. The seasonal fluctuations in macroalgal species richness and abundance were correlated with selected environmental variables. In general, the seasonal distribution patterns of these communities were distinct from those reported from other tropical and temperate regions, with higher macroalgal richness and abundance observed from late spring to late fall. Multiple linear regression analysis revealed that the stream variable most closely related with the temporal distribution pattern observed was temperature, which had a very similar seasonal pattern to the biological parameters. On the other hand, the floristic composition was quite diverse in the streams sampled. Among the 25 taxa identified, only two were common to the three streams whereas 15 were restricted to a single sampling site. These data indicate that, although temperature seems to be an effective relationship with global temporal pattern, particular characteristics of each stream can strongly influence the seasonal tendencies in local scale. The results of Detrended Correspondence Analysis (DCA) and Cluster Analysis corroborated this observation.
A dinâmica sazonal das comunidades de macroalgas foi analisada mensalmente através de amostragens em três segmentos de riachos da Bacia do Rio das Pedras, região centro-sul do Estado do Paraná, Sul do Brasil, de abril de 2004 a março de 2005. As flutuações sazonais na riqueza e abundância de espécies de macroalgas foram correlacionadas com variáveis ambientais selecionadas. Em geral, os padrões de distribuição sazonal destas comunidades foram distintos daqueles reportados para outras regiões tropicais e temperadas, com maiores valores de riqueza e abundância observados no período compreendido entre o final da primavera e o final do outono. As análises de regressão linear múltipla revelaram que a variável do riacho mais fortemente relacionada com o padrão de distribuição temporal observado foi a temperatura, que teve um padrão sazonal muito similar àqueles observados para os parâmetros biológicos. Por outro lado, a composição florística foi bastante diversa nos riachos amostrados. Dentre os 25 táxons identificados, somente dois foram comuns aos três riachos, enquanto que 15 foram restritos a um único ponto de amostragem. Estes dados indicam que, embora a temperatura pareça ter tido uma relação efetiva com o padrão temporal global, características particulares de cada riacho podem influenciar fortemente as tendências sazonais em escala local. Os resultados da Análise de Correspondência Destendenciada (ADC) e da Análise de Grupamento corroboraram esta observação.
Assuntos
Eucariotos , Água Doce , Estações do Ano , Brasil , Densidade Demográfica , Clima TropicalRESUMO
Seasonal dynamics of macroalgal communities was analyzed monthly by samplings in three stream segments of the Pedras River Basin, mid-south region of Paraná State, southern Brazil, from April 2004 to March 2005. The seasonal fluctuations in macroalgal species richness and abundance were correlated with selected environmental variables. In general, the seasonal distribution patterns of these communities were distinct from those reported from other tropical and temperate regions, with higher macroalgal richness and abundance observed from late spring to late fall. Multiple linear regression analysis revealed that the stream variable most closely related with the temporal distribution pattern observed was temperature, which had a very similar seasonal pattern to the biological parameters. On the other hand, the floristic composition was quite diverse in the streams sampled. Among the 25 taxa identified, only two were common to the three streams whereas 15 were restricted to a single sampling site. These data indicate that, although temperature seems to be an effective relationship with global temporal pattern, particular characteristics of each stream can strongly influence the seasonal tendencies in local scale. The results of Detrended Correspondence Analysis (DCA) and Cluster Analysis corroborated this observation.