Patterns of spatial distribution in macroalgal communities from tropical lotic ecosystems
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Data
2006-12-01
Autores
Borges, Fábio R. [UNESP]
Necchi Júnior, Orlando [UNESP]
Título da Revista
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Título de Volume
Editor
Sociedade Botânica de São Paulo
Resumo
Foram analisados três pontos em cada uma das três seguintes regiões tropicais: 1) região Noroeste do Estado de São Paulo, representando região degradada; 2) região de Bonito, Mato Grosso do Sul, representando ambiente de águas duras; e 3) região de Ubatuba, litoral Norte de São Paulo, ambiente de Mata Atlântica bem preservado. A região de águas duras apresentou maiores valores médios de riqueza de espécies de macroalgas e índices de diversidade (6,3 espécies por ponto e H' = 0,62). As regiões Noroeste e de Mata Atlântica apresentaram maiores valores médios de cobertura percentual (22,5% e 17,0%, respectivamente). em todos os pontos da região noroeste ocorreu uma ou duas espécies dominantes (com cobertura percentual significativamente maior que as demais), o que caracteriza o padrão de distribuição do tipo pré-ocupação de nicho. O mesmo padrão foi encontrado para dois pontos da região de mata Atlântica. Na região de águas duras foi verificada dominância de uma espécie em dois dos três pontos amostrados, mas ao contrário da região noroeste, os valores de sobreposição de nicho foram menores, evidenciando o padrão de distribuição em mosaico. A competição por espaço é um dos principais fatores que explica a distribuição espacial. de forma geral, ambientes com o padrão do tipo pré-ocupação de nicho apresentaram baixa riqueza de espécies, altos valores de sobreposição e largura de nicho, alta cobertura percentual para as espécies dominantes e altos valores para o índice de dominância. em contrapartida, ambientes com o padrão de distribuição em mosaico apresentaram alta riqueza de espécies, baixos valores de largura e sobreposição de nicho, baixa cobertura percentual e baixo índice de dominância.
Three sampling sites were analysed in each of the following tropical regions: 1) northwestern São Paulo State, representing a disturbed region; 2) Bonito, Mato Grosso do Sul State, representing a hard water region; and 3) Ubatuba, northern costal region of São Paulo State, a well preserved tropical rainforest region. The hard water region had the highest mean values for macroalgal species richness (6.3) and diversity index (H' = 0.62). Northwest and rainforest regions had the highest percent cover values (22.5% and 17.0%, respectively). All sites in the northwest region had one or two dominant species (percent cover significantly higher than the remaining species), characterizing the niche pre-emption distribution pattern. The same pattern was found in two sites of the Atlantic rainforest. The hard water region had dominance of one species in two out of the three sites, but differently from the northwest region, niche overlap values were lower, evidencing a patch distribution. Competition for space was one of the main factors to explain spatial distribution. Overall, sites characterized by niche pre-emption had lower species richness, higher values for niche width and overlap, dominance index and percent cover of dominant species. In contrast, sites characterized by patch distribution had higher species richness and lower values for niche overlap and width, dominance index and percent cover.
Three sampling sites were analysed in each of the following tropical regions: 1) northwestern São Paulo State, representing a disturbed region; 2) Bonito, Mato Grosso do Sul State, representing a hard water region; and 3) Ubatuba, northern costal region of São Paulo State, a well preserved tropical rainforest region. The hard water region had the highest mean values for macroalgal species richness (6.3) and diversity index (H' = 0.62). Northwest and rainforest regions had the highest percent cover values (22.5% and 17.0%, respectively). All sites in the northwest region had one or two dominant species (percent cover significantly higher than the remaining species), characterizing the niche pre-emption distribution pattern. The same pattern was found in two sites of the Atlantic rainforest. The hard water region had dominance of one species in two out of the three sites, but differently from the northwest region, niche overlap values were lower, evidencing a patch distribution. Competition for space was one of the main factors to explain spatial distribution. Overall, sites characterized by niche pre-emption had lower species richness, higher values for niche width and overlap, dominance index and percent cover of dominant species. In contrast, sites characterized by patch distribution had higher species richness and lower values for niche overlap and width, dominance index and percent cover.
Descrição
Palavras-chave
Distribution, Ecological niche, lotic ecosystem, macroalga, tropical region, distribuição, Ecossistema lótico, macroalga, nicho ecológico, região tropical
Como citar
Brazilian Journal of Botany. Sociedade Botânica de São Paulo, v. 29, n. 4, p. 669-680, 2006.