Photosynthetic characteristics of the freshwater red alga Batrachospermum delicatulum (Skuja) Necchi & Entwisle
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Data
2005-03-01
Autores
Necchi Júnior, Orlando [UNESP]
Alves, Abner H.S. [UNESP]
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Editor
Sociedade Botânica do Brasil
Resumo
Seis populações da alga vermelha Batrachospermum delicatulum (Skuja) Necchi & Entwisle, incluindo gametófito e estágio 'Chantransia', foram analisadas em condições de campo e cultura aplicando as técnicas de fluorescência da clorofila e oxigênio dissolvido. Parâmetros derivados das curvas fotossíntese-irradiância indicaram adaptação a baixa irradiância em todas populações, que foi caracterizada por fotoinibição, baixos valores de Ik e Ic e altos valores de a. Dados de ambas técnicas revelaram diferenças significativas entre populações e fases para a maioria dos parâmetros. A fotossíntese também respondeu diferentemente a variações de temperatura em cada população, com taxas semelhantes sob ampla faixa de temperatura. Nenhum padrão consistente foi encontrado quando a mesma população ou fase foi testada, sugerindo alta capacidade para ajustar o aparato fotossintético a distintas condições de temperatura e irradiância. Experimentos de pH mostraram tendência decrescente sob pH mais alto ou taxas maiores em pH 6,5 sugerindo, respectivamente, maior afinidade por carbono inorgânico como CO2 ou uso indistinto de bicarbonato e CO2. O padrão de variação diurna observado concorda com o de macroalgas marinhas e algumas rodófitas continentais, consistindo de dois picos: o primeiro (geralmente maior) durante a manhã e o segundo (tipicamente menor) à tarde. As características fotossintéticas de B. delicatulum (Skuja) Necchi & Entwislemostraram amplas respostas à irradiância, temperatura e pH/carbono inorgânico, refletindo sua ampla tolerância à estas variáveis, que provavelmente contribui para sua ampla distribuição espacial e temporal.
Six populations of the freshwater red alga Batrachospermum delicatulum (Skuja) Necchi & Entwisle, including gametophyte and 'Chantransia' stage, were analysed in culture and natural conditions applying chlorophyll fluorescence and oxygen evolution. Parameters derived from the photosynthesis-irradiance curves indicated adaptation to low irradiance for all populations, which was characterized by photoinhibition, low values of Ik and Ic and high values of a. Data from both techniques revealed significant differences among populations and phases for most photosynthetic parameters. Similarly, photosynthesis responded differently to variations in temperature in each population with similar rates under a wide range of temperature. No consistent pattern was found when the same population or phase was tested, suggesting high capacity to adjust the photosynthetic apparatus to distinct conditions of irradiance and temperature. pH experiments showed a decreasing trend towards higher pH or higher rates at pH 6.5, suggesting, respectively, higher affinity to inorganic carbon as CO2 or indistinct use of bicarbonate and CO2. The diurnal pattern of photosynthesis essentially agree with that for seaweeds and freshwater red algae, consisting of two peaks: a first (generally higher) during the morning and a second (typically lower) in the afternoon. Photosynthetic characteristics of B. delicatulum (Skuja) Necchi & Entwisleexhibited a wide range of responses to irradiance, temperature and pH/inorganic carbon, reflecting its wide tolerance to these variables, which probably contributes to its wide spatial and temporal distribution.
Six populations of the freshwater red alga Batrachospermum delicatulum (Skuja) Necchi & Entwisle, including gametophyte and 'Chantransia' stage, were analysed in culture and natural conditions applying chlorophyll fluorescence and oxygen evolution. Parameters derived from the photosynthesis-irradiance curves indicated adaptation to low irradiance for all populations, which was characterized by photoinhibition, low values of Ik and Ic and high values of a. Data from both techniques revealed significant differences among populations and phases for most photosynthetic parameters. Similarly, photosynthesis responded differently to variations in temperature in each population with similar rates under a wide range of temperature. No consistent pattern was found when the same population or phase was tested, suggesting high capacity to adjust the photosynthetic apparatus to distinct conditions of irradiance and temperature. pH experiments showed a decreasing trend towards higher pH or higher rates at pH 6.5, suggesting, respectively, higher affinity to inorganic carbon as CO2 or indistinct use of bicarbonate and CO2. The diurnal pattern of photosynthesis essentially agree with that for seaweeds and freshwater red algae, consisting of two peaks: a first (generally higher) during the morning and a second (typically lower) in the afternoon. Photosynthetic characteristics of B. delicatulum (Skuja) Necchi & Entwisleexhibited a wide range of responses to irradiance, temperature and pH/inorganic carbon, reflecting its wide tolerance to these variables, which probably contributes to its wide spatial and temporal distribution.
Descrição
Palavras-chave
Batrachospermum, fotossíntese, irradiância, pH, ritmo diário, temperatura, Batrachospermum, Photosynthesis, irradiance, pH, diurnal rhythm, Temperature
Como citar
Acta Botanica Brasilica. Sociedade Botânica do Brasil, v. 19, n. 1, p. 125-137, 2005.