Photoacclimation in a tropical population of Cladophora glomerata (L.) Kützing 1843 (Chlorophyta) from southeastern Brazil.

Photoacclimation of photosynthesis was investigated in a tropical population of C. glomerata (São Paulo State, southeastern Brazil, 20 degrees 48' 24" S and 49 degrees 22' 24" W) by chlorophyll fluorescence parameters and chlorophyll a content. Plants were acclimated to two levels of irradiance: low (65 +/- 5 micromol.m(-2).s(-1)) and high (300 +/- 10 micromol.m(-2).s(-1)) and exposed short-term (4 days) and long-term (28 days) under a light-dark cycle of 12:12 hours. Photosynthesis-irradiance (PI) curves revealed distinct strategies of photoacclimation. In long-term exposure, plants acclimated by altering the photosynthetic units (PSU) number and keeping fixed the PSU size, revealed by increased rates of maximum photosynthesis (Pmax), lower photosynthetic efficiency (alpha) and higher values of the saturation parameter (Ik) under high irradiance. The short-term acclimation strategy consisted of changing the PSU size, with a fixed number of PSUs, as revealed by similar Pmax but higher alpha and lower Ik under low irradiance. Chlorophyll a contents followed the general pattern reported in green algae of higher concentrations under lower irradiance. Dark/light induction curves revealed consistently higher values of potential quantum yield under low irradiance. Initial and final values showed a higher recovery capacity in the short (84.4-90.6%) term exposure than in the long-term case (81.4-81.5%). ETR (electron transport rate) and NPQ (non-photochemical quenching) values were consistently higher under low irradiance. ETR showed a continuous and steady increase along the light exposure period in the short and long-term experiments, whereas NPQ values revealed a rapid increase after 15 seconds of light exposure, kept a slightly increasing trend and stabilized in most treatments. Lower photosynthetic performance (ETR) and recovery capacity of potential quantum yield were observed, particularly in long-term exposure, suggesting that this population is constrained by the typical high light environment of tropical regions.

Photoacclimation in a tropical population of Cladophora glomerata (L.) Kützing 1843 (Chlorophyta) from southeastern Brazil

Photoacclimation of photosynthesis was investigated in a tropical population of C. glomerata (São Paulo State, southeastern Brazil, 20º 48’ 24" S and 49º 22’ 24" W) by chlorophyll fluorescence parameters and chlorophyll a content. Plants were acclimated to two levels of irradiance: low (65 ± 5 µmol.m-2.s-1) and high (300 ± 10 µmol.m-2.s-1) and exposed short-term (4 days) and long-term (28 days) under a light-dark cycle of 12:12 hours. Photosynthesis-irradiance (PI) curves revealed distinct strategies of photoacclimation. In long-term exposure, plants acclimated by altering the photosynthetic units (PSU) number and keeping fixed the PSU size, revealed by increased rates of maximum photosynthesis (Pmax), lower photosynthetic efficiency (alpha) and higher values of the saturation parameter (Ik) under high irradiance. The short-term acclimation strategy consisted of changing the PSU size, with a fixed number of PSUs, as revealed by similar Pmax but higher alpha and lower Ik under low irradiance. Chlorophyll a contents followed the general pattern reported in green algae of higher concentrations under lower irradiance. Dark/light induction curves revealed consistently higher values of potential quantum yield under low irradiance. Initial and final values showed a higher recovery capacity in the short (84.4-90.6 percent) term exposure than in the long-term case (81.4-81.5 percent). ETR (electron transport rate) and NPQ (non-photochemical quenching) values were consistently higher under low irradiance. ETR showed a continuous and steady increase along the light exposure period in the short and long-term experiments, whereas NPQ values revealed a rapid increase after 15 seconds of light exposure, kept a slightly increasing trend and stabilized in most treatments. Lower photosynthetic performance (ETR) and recovery capacity of potential quantum yield were observed, particularly in long-term exposure, suggesting that this population...

A fotoaclimatação da fotossíntese foi investigada numa população tropical de Cladophora glomerata (Estado de São Paulo, sudeste do Brasil, 20º 48’ 24" S e 49º 22’ 24" W) através de parâmetros de fluorescência da clorofila e conteúdo de clorofila a. As plantas foram aclimatadas a dois níveis de irradiância: baixa (65 ± 5 µmol.m-2.s-1) e alta (300 ± 10 :mol.m-2.s-1) e expostas a curto período (4 dias) e longo período (28 dias) em fotoperíodo de 12 horas. Curvas de fotossíntese-irradiância (FI) revelaram estratégias distintas de fotoaclimatação. Plantas expostas a longo período aclimataram pela alteração do número de unidades fotossintéticas (UF) e mantiveram fixo o tamanho das UF. Estas características foram reveladas por menores taxas de fotossíntese máxima (Fmax), menor eficiência fotossintética (alfa) e valores mais altos do parâmetro de saturação (Ik) em alta irradiância. A estratégia de aclimatação em curto período consistiu em mudança no tamanho das UF, com número fixo de UF, conforme revelado por taxas semelhantes de fotossíntese máxima (Fmax), maiores valores de alfa e menores de Ik em baixa irradiância. Os conteúdos de clorofila a seguiram o padrão geral reportado para algas verdes de maiores concentrações em baixa irradiância. Curvas de indução escuro/luz revelaram valores consistentemente mais elevados de rendimento quântico potencial em baixa irradiância. Valores iniciais e finais mostraram capacidade de recuperação mais elevada em curto período (84,4-90,6 por cento) do que em longo período (81,4-81,5 por cento). Os valores da taxa de transporte de elétrons (ETR) e extinção não-fotoquímica (NPQ) foram consistentemente mais elevados em baixa irradiância. Os valores de ETR tiveram aumento contínuo e estável ao longo do período de exposição luminosa em curto e longo períodos, enquanto que os de NPQ revelaram aumento rápido após 15 seconds de exposição à luz, mantiveram leve tendência de aumento e então estabilizaram...

Photoacclimation in a tropical population of Cladophora glomerata (L.) Kützing 1843 (Chlorophyta) from southeastern Brazil

Photoacclimation of photosynthesis was investigated in a tropical population of C. glomerata (São Paulo State, southeastern Brazil, 20º 48 24" S and 49º 22 24" W) by chlorophyll fluorescence parameters and chlorophyll a content. Plants were acclimated to two levels of irradiance: low (65 ± 5 µmol.m-2.s-1) and high (300 ± 10 µmol.m-2.s-1) and exposed short-term (4 days) and long-term (28 days) under a light-dark cycle of 12:12 hours. Photosynthesis-irradiance (PI) curves revealed distinct strategies of photoacclimation. In long-term exposure, plants acclimated by altering the photosynthetic units (PSU) number and keeping fixed the PSU size, revealed by increased rates of maximum photosynthesis (Pmax), lower photosynthetic efficiency (alpha) and higher values of the saturation parameter (Ik) under high irradiance. The short-term acclimation strategy consisted of changing the PSU size, with a fixed number of PSUs, as revealed by similar Pmax but higher alpha and lower Ik under low irradiance. Chlorophyll a contents followed the general pattern reported in green algae of higher concentrations under lower irradiance. Dark/light induction curves revealed consistently higher values of potential quantum yield under low irradiance. Initial and final values showed a higher recovery capacity in the short (84.4-90.6%) term exposure than in the long-term case (81.4-81.5%). ETR (electron transport rate) and NPQ (non-photochemical quenching) values were consistently higher under low irradiance. ETR showed a continuous and steady increase along the light exposure period in the short and long-term experiments, whereas NPQ values revealed a rapid increase after 15 seconds of light exposure, kept a slightly increasing trend and stabilized in most treatments. Lower photosynthetic performance (ETR) and recovery capacity of potential quantum yield were observed, particularly in long-term exposure, suggesting that this population is constrained by the typical high light environment of tropical regions.

A fotoaclimatação da fotossíntese foi investigada numa população tropical de Cladophora glomerata (Estado de São Paulo, sudeste do Brasil, 20º 48 24" S e 49º 22 24" W) através de parâmetros de fluorescência da clorofila e conteúdo de clorofila a. As plantas foram aclimatadas a dois níveis de irradiância: baixa (65 ± 5 µmol.m-2.s-1) e alta (300 ± 10 :mol.m-2.s-1) e expostas a curto período (4 dias) e longo período (28 dias) em fotoperíodo de 12 horas. Curvas de fotossíntese-irradiância (FI) revelaram estratégias distintas de fotoaclimatação. Plantas expostas a longo período aclimataram pela alteração do número de unidades fotossintéticas (UF) e mantiveram fixo o tamanho das UF. Estas características foram reveladas por menores taxas de fotossíntese máxima (Fmax), menor eficiência fotossintética (alfa) e valores mais altos do parâmetro de saturação (Ik) em alta irradiância. A estratégia de aclimatação em curto período consistiu em mudança no tamanho das UF, com número fixo de UF, conforme revelado por taxas semelhantes de fotossíntese máxima (Fmax), maiores valores de alfa e menores de Ik em baixa irradiância. Os conteúdos de clorofila a seguiram o padrão geral reportado para algas verdes de maiores concentrações em baixa irradiância. Curvas de indução escuro/luz revelaram valores consistentemente mais elevados de rendimento quântico potencial em baixa irradiância. Valores iniciais e finais mostraram capacidade de recuperação mais elevada em curto período (84,4-90,6%) do que em longo período (81,4-81,5%). Os valores da taxa de transporte de elétrons (ETR) e extinção não-fotoquímica (NPQ) foram consistentemente mais elevados em baixa irradiância. Os valores de ETR tiveram aumento contínuo e estável ao longo do período de exposição luminosa em curto e longo períodos, enquanto que os de NPQ revelaram aumento rápido após 15 seconds de exposição à luz, mantiveram leve tendência de aumento e então estabilizaram na maioria dos tratamentos. Performances fotossintéticas inferiores e menor capacidade de recuperação do rendimento quântico potencial foram observadas, sugerindo que esta população sofre inibições pelo típico ambiente de alta irradiância de regiões tropicais.

Ecological distribution of stream macroalgal communities from a drainage basin in the Serra da Canastra National Park, Minas Gerais, Southeastern Brazil

Twelve stream segments were sampled four times in 1998-1999 (one sampling per season) in the drainage basin of the upper São Francisco River (19º45'-21º25'S, 49º05'-51º30'W), situated in Serra da Canastra National Park, at altitudes ranging from 1,175 to 1,400 m. The macroalgae survey resulted in 30 species, with a predominance of Cyanophyta (12 species = 40 percent) and Chlorophyta (11 species = 36.5 percent) and a lower proportion of Rhodophyta (seven species = 23.5 percent). Two species, Klebsormidium rivulare (Chlorophyta) and Kyliniella latvica (Rhodophyta), were new records for Brazil. Capsosira sp. and Stigonema sp. (Cyanophyta) and the "Chantransia" stage of Batrachospermum (Rhodophyta) were the most widespread macroalgae, occurring in six sampling sites, whereas 11 species were found at only one site. The proportion of macroalgal morphological types were as follows: mats (33 percent), free filaments (27 percent), gelatinous filaments (27 percent), crusts (7 percent), tufts (3 percent), and gelatinous colonies (3 percent). The flora revealed few species in common (4 percent-8 percent) with stream macroalgae from other Brazilian regions. The macroalgal communities proved to have species richness values close to the highest values reported in previous studies. The patterns typical for stream macroalgal communities (patchy distribution and dominance of few species) were also found in this basin. However, the stream variables most influential in macroalgal distribution in this study (rocky substratum, low pH, high COD, water color, and current velocity) were essentially the same that best describe the limnological characteristics of this lotic ecosystem. In addition, this combination of variables differed sharply from results of previous studies in other Brazilian stream ecosystems.

Ecological distribution of stream macroalgal communities from a drainage basin in the Serra da Canastra National Park, Minas Gerais, Southeastern Brazil.

Twelve stream segments were sampled four times in 1998-1999 (one sampling per season) in the drainage basin of the upper São Francisco River (19 masculine 45'-21 masculine 25'S, 49 masculine 05'-51 masculine 30'W), situated in Serra da Canastra National Park, at altitudes ranging from 1,175 to 1,400 m. The macroalgae survey resulted in 30 species, with a predominance of Cyanophyta (12 species = 40%) and Chlorophyta (11 species = 36.5%) and a lower proportion of Rhodophyta (seven species = 23.5%). Two species, Klebsormidium rivulare (Chlorophyta) and Kyliniella latvica (Rhodophyta), were new records for Brazil. Capsosira sp. and Stigonema sp. (Cyanophyta) and the "Chantransia" stage of Batrachospermum (Rhodophyta) were the most widespread macroalgae, occurring in six sampling sites, whereas 11 species were found at only one site. The proportion of macroalgal morphological types were as follows: mats (33%), free filaments (27%), gelatinous filaments (27%), crusts (7%), tufts (3%), and gelatinous colonies (3%). The flora revealed few species in common (4%-8%) with stream macroalgae from other Brazilian regions. The macroalgal communities proved to have species richness values close to the highest values reported in previous studies. The patterns typical for stream macroalgal communities (patchy distribution and dominance of few species) were also found in this basin. However, the stream variables most influential in macroalgal distribution in this study (rocky substratum, low pH, high COD, water color, and current velocity) were essentially the same that best describe the limnological characteristics of this lotic ecosystem. In addition, this combination of variables differed sharply from results of previous studies in other Brazilian stream ecosystems.

Ecological distribution of stream macroalgal communities from a drainage basin in the Serra da Canastra National Park, Minas Gerais, Southeastern Brazil

Twelve stream segments were sampled four times in 1998-1999 (one sampling per season) in the drainage basin of the upper São Francisco River (19º45'-21º25'S, 49º05'-51º30'W), situated in Serra da Canastra National Park, at altitudes ranging from 1,175 to 1,400 m. The macroalgae survey resulted in 30 species, with a predominance of Cyanophyta (12 species = 40%) and Chlorophyta (11 species = 36.5%) and a lower proportion of Rhodophyta (seven species = 23.5%). Two species, Klebsormidium rivulare (Chlorophyta) and Kyliniella latvica (Rhodophyta), were new records for Brazil. Capsosira sp. and Stigonema sp. (Cyanophyta) and the "Chantransia" stage of Batrachospermum (Rhodophyta) were the most widespread macroalgae, occurring in six sampling sites, whereas 11 species were found at only one site. The proportion of macroalgal morphological types were as follows: mats (33%), free filaments (27%), gelatinous filaments (27%), crusts (7%), tufts (3%), and gelatinous colonies (3%). The flora revealed few species in common (4%-8%) with stream macroalgae from other Brazilian regions. The macroalgal communities proved to have species richness values close to the highest values reported in previous studies. The patterns typical for stream macroalgal communities (patchy distribution and dominance of few species) were also found in this basin. However, the stream variables most influential in macroalgal distribution in this study (rocky substratum, low pH, high COD, water color, and current velocity) were essentially the same that best describe the limnological characteristics of this lotic ecosystem. In addition, this combination of variables differed sharply from results of previous studies in other Brazilian stream ecosystems.

Doze segmentos de riachos foram amostrados quatro vezes em 1998-1999 (uma amostragem em cada estação) na bacia de drenagem do alto rio São Francisco (19º45'-21º25'S, 49º05'-51º30'W), situado no Parque Nacional da Serra da Canastra, em altitudes de 1.175 a 1.400 m. O levantamento das macroalgas resultou em 30 espécies, com predominância de Cyanophyta (12 espécies = 40%) e Chlorophyta (11 espécies = 36,5%) e menor proporção de Rhodophyta (sete espécies = 23,5%). Duas espécies, Klebsormidium rivulare (Chlorophyta) e Kyliniella latvica (Rhodophyta), constituem novos registros para o Brasil. Capsosira sp. e Stigonema sp. (Cyanophyta) e o estágio "Chantransia" de Batrachospermum (Rhodophyta) foram as macroalgas mais amplamente distribuídas, ocorrendo em 6 pontos de amostragem, enquanto 11 espécies foram encontradas em apenas um ponto. As proporções de tipos morfológicos de macroalgas foram as seguintes: emaranhado de filamentos (33%), filamentos livres (27%), filamentos gelatinosos (7%), crostas (7%) e tufos e colônias gelatinosas (3%). A flora teve poucas espécies em comum (4%-8%) com macroalgas lóticas de outras regiões brasileiras. As comunidades de macroalgas mostraram-se ricas, com valores de riqueza de espécies próximos aos mais altos anteriormente reportados. Os padrões típicos para comunidades de macroalgas lóticas de distribuição em mosaico e dominância de poucas espécies também foram encontrados nessa bacia. Entretanto, as variáveis ambientais mais influentes sobre a distribuição de macroalgas neste estudo (substrato rochoso, baixos valores de pH e altos de DQO, cor da água e velocidade da correnteza) foram essencialmente as mesmas que melhor descreveram as características limnológicas desse ecossistema lótico. Além disso, essa combinação de variáveis foi nitidamente diferente dos resultados de estudos anteriores em outros ecossistemas lóticos brasileiros.

[Use of macroalgae for the evaluation of organic pollution in the Preto river, northwest of São Paulo State]. / Uso de macroalgas para avaliação da Poluição orgânica no Rio Preto, noroeste do estado de São Paulo.

The Preto River, located in the northwest of São Paulo State, receives a total wastewater load of 15.150 kg DBO day-1, from which 13.685 kg DBO day-1 (90.5%) corresponds to domestic sewage, and the city of São José do Rio Preto contributes with 12.400 kg DBO day-1 (90% of domestic sewage). During the period from August 1990 through January 1991, monthly sampling was carried out to evaluate the use of macroalgae as bioindicator of organic pollution. Five sampling sites were established along the main river and the following variables were analised: temperature, conductance, turbidity, dissolved oxygen, BOD, COD, total and fecal coliforms, and composition and abundance of macroalgal communities. Data were submitted to analysis of variance, correlation coefficient, cluster analysis (four different approaches) and converted to biological indices (species deficit, relative pollution, saprobity, diversity and uniformity indices). A wide range in water quality was found (particularly for conductance, oxygen, BOD and COD) among the sampling sites, which were classified into three groups (polluted, moderately polluted and unpolluted/weakly polluted). As regards the occurrence and abundance of macroalgae the Rhodophyta were found only in unpolluted or weakly polluted sites, whereas Cyanophyta occurred mostly under high pollution load; the Chlorophyta species were observed under a wide range of conditions. Among the biological indices, saprobity was the most sensitive and correlated to all water variables and the other indices. Cluster analyses showed that the composition of macroalgal communities was consistent with the levels of organic pollution in the Preto River.