RESUMO
This study assessed the influence of the seasonal fluctuation of abiotic conditions (wet v. dry season) on the functional diversity (FD) of tropical coastal fish assemblages. Sampling was carried out in three regions of north-east Brazil with contrasting coastlines (influenced by reef, lagoon and estuary). In each region, fishes were sampled from three depth strata (10, 20 and 30 m) and FD was estimated using an index based on key phenotypic and behavioural characteristics. All three regions had higher FD in the wet season at shallower depths, indicating the coexistence of species with low functional redundancy in sites subject to seasonal flushing of fresh water. Deeper sites had lower FD than shallower sites, although this difference was less pronounced for region 3, which is strongly affected by its proximity to the São Francisco estuary. The results broadly support the hypothesis that alterations in abiotic conditions in the wet season allow estuarine-adapted fishes with a different suite of functional traits to invade shallow coastal regions.
Assuntos
Ecossistema , Estuários , Peixes , Animais , Brasil , Água Doce , Estações do AnoRESUMO
In this paper we calculate the values of eight pattern detection indices, using different quadrat sizes where individuals of angico above 1.5 m were located, in order to examine their statistical behaviour with increasing sample size. It was concluded that the best index is the standardized Morisita index (Ip) which is completely independent of sample size.
Assuntos
Fabaceae , Brasil , Densidade DemográficaRESUMO
Neste trabalho calculamos os valores de oito índices de detecção de padräes, usando quadratins de tamanhos diferentes, onde indivíduos de angico com mais de 1,5 m estavam localizados, a fim de examinar seus comportamentos estatísticos com o aumento do tamanho da amostra. Conclui-se que o melhor índice é de Morisita padronizado (Ip), o qual é independente do tamanho da amostra.