Cosmarium bromelicola sp. nov. (Desmidiaceae, Zygnematophyceae), a new desmid species from Northeast Brazil / Cosmarium bromelicola sp. nov. (Desmidiaceae, Zygnematophyceae), uma nova espécie de desmídia do nordeste do Brazil

Abstract Cosmarium bromelicola sp. nov. is a new desmid species described from samplings carried out in bromeliad tanks (phytotelmata) from an area of rocky outcrops at Serra da Jiboia, Bahia State, Northeast Brazil. Presence of subtrapeziform cells with a deep depression at the apical region and twisted X-shaped cell in side view are the diagnostic features for the species. Relationships with the morphologically closest taxa are discussed.

Resumo Cosmarium bromelicola sp. nov. é uma nova espécie de desmídia descrita a partir de amostragens realizadas em tanques de bromélias (fitotelmata) de uma área de afloramentos rochosos na Serra da Jiboia, Bahia, nordeste do Brasil. A presença de células trapeziformes com uma depressão profunda na região apical e célula em forma de X em vista lateral são as características diagnósticas da espécie. Relações com os táxons morfologicamente próximos são discutidas.

Cosmarium bromelicola sp. nov. (Desmidiaceae, Zygnematophyceae), a new desmid species from Northeast Brazil.

Cosmarium bromelicola sp. nov. is a new desmid species described from samplings carried out in bromeliad tanks (phytotelmata) from an area of rocky outcrops at Serra da Jiboia, Bahia State, Northeast Brazil. Presence of subtrapeziform cells with a deep depression at the apical region and twisted X-shaped cell in side view are the diagnostic features for the species. Relationships with the morphologically closest taxa are discussed.

Seasonal variation of limnological features and trophic state index of two oligotrophic reservoirs of southeast Brazil / Variação sazonal das características limnológicas e Índice de Estado Trófico de dois reservatórios oligotróficos do sudeste do Brasil

Abstract Limnological features of two reservoirs were studied in dry (August 2013) and rainy (January 2014) periods to evaluate the water quality that supply the city of Guarulhos, southeast Brazil. Water samples were collected in three depths and the following characteristics were measured: alkalinity, dissolved O2, free and total CO2, HCO3, soluble reactive silica, dissolved and total nitrogen and phosphorus, and chlorophyll-a. Water transparency was also measured and temperature, pH and electric conductivity profiles were obtained. Great seasonal and low spatial variability of the water characteristics occurred in the reservoirs. High values of water transparency, free CO2 availability, and low of pH, soluble reactive silica and total and dissolved nutrients values were recorded at the dry period, and different conditions were found at the rainy season. The two reservoirs were characterized by low nutrients, chlorophyll-a and turbidity, and high transparency, these features being typical of oligotrophic systems. The two reservoirs still remain under low anthropogenic impact conditions, and are presently considered reference systems for the SPMR, São Paulo Metropolitan Region. The need for actions that will reduce the input of nutrients from the neighboring cities and the main tributaries of the hydrographic basin is emphasized to maintain the ecological quality of the reservoirs and their reference conditions among the SPRM reservoirs.

Resumo Características limnológicas de dois reservatórios foram estudadas durante os períodos seco (Agosto 2013) e de chuvas (Janeiro 2014) para avaliar a qualidade da água que abastece a cidade de Guarulhos, Brasil sudeste. Amostras de água foram coletadas em três profundidades e as características estudadas foram: alcalinidade, O2 dissolvido, CO2 livre e total, HCO3, sílica reativa solúvel e nitrogênio e fósforo dissolvido e total e clorofila-a. Transparência da água foi medida e obtidos os perfis de temperatura, pH e condutividade elétrica. Grande variabilidade sazonal e espacial das características da água ocorreu nos reservatórios. Altos valores de transparência da água, disponibilidade de CO2 livre e menores de pH, sílica reativa solúvel e nutrientes totais e dissolvidos foram documentados durante o período seco; e condições diferentes durante o período de chuvas. Os dois reservatórios foram caracterizados por baixos teores de nutrientes, clorofila-a e turbidez e alta transparência, características estas típicas de sistemas oligotróficos. Os dois reservatórios ainda permanecem sob condição de baixo impacto antropogênico e são atualmente considerados sistemas de referência para a RMSP, Região Metropolitana de São Paulo. A necessidade de ações para diminuir e até frear a entrada de nutrientes provenientes das cidades vizinhas e dos principais afluentes da bacia hidrográfica é enfatizada para manter a qualidade ecológica dos reservatórios e suas condições de referência entre os reservatórios da RMSP.

Seasonal variation of limnological features and trophic state index of two oligotrophic reservoirs of southeast Brazil.

Limnological features of two reservoirs were studied in dry (August 2013) and rainy (January 2014) periods to evaluate the water quality that supply the city of Guarulhos, southeast Brazil. Water samples were collected in three depths and the following characteristics were measured: alkalinity, dissolved O2, free and total CO2, HCO3, soluble reactive silica, dissolved and total nitrogen and phosphorus, and chlorophyll-a. Water transparency was also measured and temperature, pH and electric conductivity profiles were obtained. Great seasonal and low spatial variability of the water characteristics occurred in the reservoirs. High values of water transparency, free CO2 availability, and low of pH, soluble reactive silica and total and dissolved nutrients values were recorded at the dry period, and different conditions were found at the rainy season. The two reservoirs were characterized by low nutrients, chlorophyll-a and turbidity, and high transparency, these features being typical of oligotrophic systems. The two reservoirs still remain under low anthropogenic impact conditions, and are presently considered reference systems for the SPMR, São Paulo Metropolitan Region. The need for actions that will reduce the input of nutrients from the neighboring cities and the main tributaries of the hydrographic basin is emphasized to maintain the ecological quality of the reservoirs and their reference conditions among the SPRM reservoirs.

Morphological variation in Staurastrum rotula (Zygnemaphyceae, Desmidiales) in the deepest natural Brazilian lake: essence or accident?

For many decades, polymorphism and its consequences have only been studied from the taxonomic point of view. Presently, interest has switched to the environmental causes of morphological variation and its consequences in the form and essence of the species. This study aimed at evaluating desmids morphological modifications of Staurastrum rotula Nordstedt during inter-annual succession patterns in two warm monomitic tropical lakes: Dom Helvécio (19°45'- 19°48'45″S, 42°33'45″W) and Carioca (19°45'20″S, 42°37'12″W). The effect of thermal stability and light and nutrients availability was based on samples collected monthly from January 2002 to December 2006 compared the morphological modifications. Results indicated that morphological variation, asexual reproduction, theratological forms, mucilaginous envelope and fungal infection were highest in Lake Dom Helvécio and coincided with the biomass increase of species with complex morphology between September and March (stratification period). The Zmix oscillation, wind and rainfall occurring at the end of the mixing period and beginning of the stratification were suggested as autochthonous and allochthonous disturbance agents, respectively, identified as inducers of asexual reproduction and consequently of the morphological variation. It was suggested that incidence of parasitism may act as a potential controlling agent for the Staurastrum rotula population size. It was concluded that morphological variation represents accidents in the original form, i.e. in the desmid species essence, promoting the existence of ecoforms, not of new infraspecific taxa.

Phytoplankton biodiversity changes in a shallow tropical reservoir during the hypertrophication process / Mudanças na biodiversidade fitoplanctônica em um reservatório tropical raso durante o processo de hipereutrofização

Study aimed at evaluating phytoplankton biodiversity changes in a shallow tropical reservoir during its hypertrophication process. Samplings were carried out monthly during 8 consecutive years (1997-2004) in 5 depths. Conspicuous limnological changes in the reservoir derived from the presence and/or removal of the water hyacinth, characterized 3 different phases. Over the time series, reservoir changed from a typical polymictic eutrophic system to hypertrophic one, leading to a reduction of approximately 70 species (average 37 percent). Chlorophyceae accounted for the highest species richness (46 percent) among all algal classes and strictly followed total species richness variation. Internal feedback mechanisms intensification over phase III clearly promoted the sharp decrease in biodiversity. Highest decreases, mainly during springs, occurred simultaneously to the highest Cyanobacteria blooms. Increased turbidity due to heavy phytoplankton blooms suppressed all other algal groups, so that at the end of the present study even Cyanobacteria species richness decreased. Total dissolved phosphorous was included in most of the best selected models used to analyze the temporal patterns in species richness loss. Present data show that biodiversity loss following trophic change was not a single dimension of a single factor but, rather, a template of factors (e.g. light, stability) co-varying in consequence of the larger levels of biomass supported in the reservoir.

Estudo avaliou as mudanças na biodiversidade da comunidade fitoplanctônica em um reservatório tropical raso durante processo de hipereutrofização. Foram realizadas amostragens mensais durante oito anos consecutivos (1997-2004) em cinco profundidades. Mudanças limnológicas conspícuas no reservatório foram a conseqüência da presença e/ou remoção do aguapé, caracterizando três fases limnológicas. Durante a série temporal, o reservatório mudou de um sistema eutrófico polimítico típico para um sistema hipereutrófico, levando à redução de aproximadamente 70 espécies (média de 37 por cento). Chlorophyceae foi a classe com a maior riqueza de espécies (46 por cento) entre todas e seguiu, intimamente, a variação da riqueza total de espécies. A intensificação dos mecanismos internos de retroalimentação durante a fase III claramente promoveram uma acentuada queda da biodiversidade. Os decréscimos mais acentuados, especialmente durante as primaveras, ocorreram simultaneamente às maiores florações de Cyanobacteria. O aumento de turbidez provocado pelas florações maciças suprimiu outros grupos de algas de forma que, no final do presente estudo, até mesmo a riqueza de Cyanobacteria decaiu. Fósforo total dissolvido foi incluído na maioria dos melhores modelos selecionados para análise dos padrões temporais da perda da biodiversidade. Os presentes dados mostram que a perda da biodiversidade durante a mudança trófica não esteve relacionada a apenas um fator, mas a um conjunto deles (exemplos: luz, estabilidade), que co-variaram em conseqüência dos elevados níveis de biomassa mantidos pelo reservatório.

Phytoplankton biodiversity changes in a shallow tropical reservoir during the hypertrophication process.

Study aimed at evaluating phytoplankton biodiversity changes in a shallow tropical reservoir during its hypertrophication process. Samplings were carried out monthly during 8 consecutive years (1997-2004) in 5 depths. Conspicuous limnological changes in the reservoir derived from the presence and/or removal of the water hyacinth, characterized 3 different phases. Over the time series, reservoir changed from a typical polymictic eutrophic system to hypertrophic one, leading to a reduction of approximately 70 species (average 37%). Chlorophyceae accounted for the highest species richness (46%) among all algal classes and strictly followed total species richness variation. Internal feedback mechanisms intensification over phase III clearly promoted the sharp decrease in biodiversity. Highest decreases, mainly during springs, occurred simultaneously to the highest Cyanobacteria blooms. Increased turbidity due to heavy phytoplankton blooms suppressed all other algal groups, so that at the end of the present study even Cyanobacteria species richness decreased. Total dissolved phosphorous was included in most of the best selected models used to analyze the temporal patterns in species richness loss. Present data show that biodiversity loss following trophic change was not a single dimension of a single factor but, rather, a template of factors (e.g. light, stability) co-varying in consequence of the larger levels of biomass supported in the reservoir.

Diurnal and spatial (vertical) dynamics of nutrients (N, P, Si) in four sampling days (summer, fall, winter, and spring) in a tropical shallow reservoir and their relationships with the phytoplankton community.

The vertical and diurnal variation of nitrogen and phosphorus forms, as well as that of soluble reactive silica (SRS), were studied in four sampling days at Gar9as reservoir, a shallow tropical one located in the city of São Paulo, in southeastern Brazil. Except for N-NH4, all other inorganic forms of nitrogen (N-NO2, N-NO3, and total N) demonstrated decreased concentrations toward the bottom of reservoir. Similarly, all showed significant diurnal differences on every sampling day, with increased values during the night due to absence of photosynthetic assimilation during that period. In the sampling days, these forms decreased on the spring sampling day due to the bloom of Microcystis registered during this period of the year. All three forms of phosphorus (SRP, particulate P, and total P) showed significant vertical variation, except on the fall sampling day. On the summer sampling day there was an increase of both total P and particulate P, the latter because it constitutes more than 70% of the total P during all sampling days. Hourly phosphorus variation was significant during all sampling days, except for the summer one. The SRS vertical variation was significant during all sampling days, except for that in the spring. It was also different hourly on sampling days.

Diurnal and spatial (vertical) dynamics of nutrients (N, P, Si) in four sampling days (summer, fall, winter, and spring) in a tropical shallow reservoir and their relationships with the phytoplankton community

Variações vertical, nictemeral e entre os dias de amostragem das formas de nitrogênio, fósforo e sílica solúvel reativa (SRS) foram estudadas no lago das Garças, reservatório tropical raso situado na cidade de São Paulo, sudeste do Brasil. Excetuado o N-NH4, todas as demais formas inorgânicas de nitrogênio (N-NO2, N-NO3 e N total) diminuíram de teor no sentido do fundo do reservatório. Da mesma maneira, todas as formas de nitrogênio apresentaram diferenças significativas quanto às horas de amostragem, aumentando seus valores durante a noite, em razão da ausência de fotossíntese nesse período. Essas formas diminuíram seus teores no dia de amostragem da primavera, graças à floração de Microcystis registrada nesse período. Os valores das três formas de fósforo estudadas (solúvel reativo, particulado e total) apresentaram variação vertical significativa, exceto no dia da amostragem de outono. No dia de amostragem de verão ocorreu aumento dos valores de P total e particulado, sendo que este último constituiu mais de 70% do P total durante todos os dias de amostragem. Considerando as horas, a variação dos teores de fósforo foi significativa nos dias das amostragem de primavera, de outono e de inverno. A variação vertical da sílica reativa solúvel foi significativa em todos os dias de amostragem, menos no da primavera. Essa variação também foi diferente entre as horas e os dias de amostragem.

Variation of climatic and physical co-determinants of phytoplankton community in four nictemeral sampling days in a shallow tropical reservoir, southeastern Brazil.

Spatial and temporal variation of climatic and physical characteristics in a shallow tropical reservoir in the city of São Paulo, Southeastern Brazil, and their possible influence on the dynamics of the phytoplankton population. Samples were taken at 5 depths of the water column (subsurface: 1% Io, 10% Io, 2 m, and bottom) and at 4 hour intervals (6:00, 10:00, 14:00, 18:00, 22:00, 2:00, and 6:00 h) during summer (March 3-4), fall (June 13-14), winter (August 29-30), and spring (November 29-30) of 1994 at a single sampling station. Garças Reservoir (23 degrees 39'S, 46 degrees 37'W) is a kinetic turbulent system, highly influenced by winds, with stratification that may last for days or weeks, and which undergoes mixing periods more than once in a year. A thermal pattern of this type is comparable to the warm discontinuous polymetric. Considering its optical properties, the water body was classified as an ecosystem with moderate turbidity, which decreases basically due to increased phacopigment concentration during the spring. Also, the reservoir is an ecosystem whose phytoplanktonic community is subjected to stress, the degree of which depends on level of light penetration.

Variation of climatic and physical co-determinants of phytoplankton community in four nictemeral sampling days in a shallow tropical reservoir, Southeastern Brazil

Spatial and temporal variation of climatic and physical characteristics in a shallow tropical reservoir in the city of Säo Paulo, Southeastern Brazil, and their possible influence on the dynamics of the phytoplankton population. Samples were taken at 5 depths of the water column (subsurface: 1 percent Io, 10 percent Io, 2 m, and bottom) and at 4 hour intervals (6:00, 10:00, 14:00, 18:00, 22:00, 2:00, and 6:00 h) during summer (March 3-4), fall (June 13-14), winter (August 29-30), and spring (November 29-30) of 1994 at a single sampling station. Garças Reservoir (23º39'S, 46º37'W) is a kinetic turbulent system, highly influenced by winds, with stratification that may last for days or weeks, and which undergoes mixing periods more than once in a year. A thermal pattern of this type is comparable to the warm discontinuous polymictic. Considering its optical properties, the water body was classified as an ecosystem with moderate turbidity, which decreases basically due to increased phaeopigment concentration during the spring. Also, the reservoir is an ecosystem whose phytoplanktonic community is subjected to stress, the degree of which depends on level of light penetration