Sucessão da comunidade de algas perifíticas em reservatório oligotrófico tropical (São Paulo, Brasil): comparação entre período seco e chuvoso
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Data
2006-09-01
Autores
Vercellino, Ilka Schincariol [UNESP]
Bicudo, Denise de Campos
Título da Revista
ISSN da Revista
Título de Volume
Editor
Sociedade Botânica de São Paulo
Resumo
O trabalho visou avaliar a influência da escala temporal (sucessional e sazonal) sobre a biomassa, diversidade e estrutura específica da comunidade de algas perifíticas em reservatório oligotrófico tropical. A sucessão foi acompanhada em períodos seco e chuvoso com amostragens regulares a cada três dias, durante 27 dias, incluindo 16 variáveis abióticas e atributos do perifíton sobre substrato artificial. A clorofila-a foi baixa e similar entre períodos, porém com maiores perdas na época chuvosa. A diversidade foi elevada (3,4 a 4,5 bits ind-1) e relativamente estável entre períodos e durante a sucessão. As clorofíceas foram a classe mais abundante em quase toda sucessão, com destaque para Chlamydomonas planctogloea Skuja que contribuiu em média com 23% (seca) e 37% (chuva) da densidade total. A análise integrada entre as espécies e os fatores ambientais mostrou que a principal fonte de variabilidade ocorreu em função do período climático. Oocystis lacustris Chodat e Gymnodinium sp. apresentaram estreita associação com o período seco e aos menores valores de temperatura, amônio e maiores de pH, oxigênio dissolvido e fósforo total. Ao período chuvoso associaram-se Frustulia rhomboides (Ehr.) de Toni var. rhomboides e Cosmarium majae Strom correlacionadas de forma inversa às variáveis ambientais citadas. A estrutura do perifíton foi primordialmente controlada pela escala climática, sendo que os processos autogênicos sucessionais tiveram papel secundário. As associações de espécies de algas e o processo de acumulação de biomassa foram os atributos mais sensíveis a esta variação. Tais resultados contribuem para o escasso conhecimento sobre a estruturação do perifíton de reservatórios oligotróficos, servindo de referência para avaliação de sistemas tropicais alterados pela eutrofização.
This study aimed at evaluating the time scale influence (successional and seasonal) on the periphyton biomass, diversity, and algal community structure in a tropical oligotrophic reservoir, southeast Brazil. Succession process was followed during dry and rainy periods by every 3-day samplings over 27 days, and included 16 abiotic variables and periphyton properties on artificial substrate. Chlorophyll-a values were low and similar between periods, however, with the highest loss rates observed during the rainy season. Shannon diversity was high (3.4-4.5 bits ind-1) and relatively stable among periods and along the entire succession. Chlorophyceae was the most abundant class over succession, mainly represented by Chlamydomonas planctogloea Skuja that contributed with 23% (dry) and 37% (rainy) of the mean total density. Integrated analysis of species and environmental variables revealed climatic period as the main driving force on periphyton structure. Oocystis lacustris Chodat and Gymnodinium sp. were associated with dry period and lower temperature and ammonium values, as well as with higher pH, dissolved oxygen, and total phosphorus levels. Frustulia rhomboides (Ehr.) de Toni var. rhomboides and Cosmarium majae Strom were associated with rainy season and, inversely, to the dry season abiotic variables. Periphyton community was mainly controlled by the climatic period, the autogenic succession being of less importance. Photosynthetic biomass accrual process and periphytic algal species assemblages were more sensitive to such variation. Present results contribute to a better understanding of the periphyton community structuring in oligotrophic reservoirs, providing a reference for changes in degraded tropical systems.
This study aimed at evaluating the time scale influence (successional and seasonal) on the periphyton biomass, diversity, and algal community structure in a tropical oligotrophic reservoir, southeast Brazil. Succession process was followed during dry and rainy periods by every 3-day samplings over 27 days, and included 16 abiotic variables and periphyton properties on artificial substrate. Chlorophyll-a values were low and similar between periods, however, with the highest loss rates observed during the rainy season. Shannon diversity was high (3.4-4.5 bits ind-1) and relatively stable among periods and along the entire succession. Chlorophyceae was the most abundant class over succession, mainly represented by Chlamydomonas planctogloea Skuja that contributed with 23% (dry) and 37% (rainy) of the mean total density. Integrated analysis of species and environmental variables revealed climatic period as the main driving force on periphyton structure. Oocystis lacustris Chodat and Gymnodinium sp. were associated with dry period and lower temperature and ammonium values, as well as with higher pH, dissolved oxygen, and total phosphorus levels. Frustulia rhomboides (Ehr.) de Toni var. rhomboides and Cosmarium majae Strom were associated with rainy season and, inversely, to the dry season abiotic variables. Periphyton community was mainly controlled by the climatic period, the autogenic succession being of less importance. Photosynthetic biomass accrual process and periphytic algal species assemblages were more sensitive to such variation. Present results contribute to a better understanding of the periphyton community structuring in oligotrophic reservoirs, providing a reference for changes in degraded tropical systems.
Descrição
Palavras-chave
biomassa, diversidade, estrutura de comunidade, perifíton, riqueza, biomass, community structure, diversity, periphyton, richness
Como citar
Brazilian Journal of Botany. Sociedade Botânica de São Paulo, v. 29, n. 3, p. 363-377, 2006.