FLORAÇÕES DE Microcystis NA LAGOA DOS PATOS E O SEU ESTUÁRIO: 20 ANOS DE ESTUDOS

revista vol 13 nº 2.indd  Cyanobacterial blooms of Microcystis are frequent in the Patos Lagoon and estuary located in Rio Grande do Sul State, Brazil. Although the first scientific record of such occurrence dates to 1987, local villagers claim cyanobacterial blooms have occurred in the area since the begining of the 20th century. Great blooms of M. aeruginosa take place during the summer and fall, as a result of seasonal swells in the estuary and suitable abiotic conditions, as N:P ratios between 10:1 and 16:1 and water temperatures above 20ºC. The reduced water outflow enables the growth of Microcystis populations, and the surplus of sea salt directly affects intracellular and extracellular composition of microcystins. The strain RST9501 was isolated in the summer of 1995 from a cyanobacterial bloom in the area, and the cells proved toxic to mice, microcrustaceans and shrimp. This strain presents four types of microcystins, mainly D-Leu1 MCyst-LR. These toxins also demonstrated to accumulate in marine shellfish from the South Atlantic Sea and in freshwater fish. The toxicity of RST9501 cells was demonstrated by oxidative stress to polychaetes, sea crabs and osmoregulatory alterations in fish. The microcystins isolated from the Lagoa dos Patos lagoon are consumed by bacteria of the genus Burkholderia. Local blooms demonstrated to present toxins related to the quantity of Microcystis cells and caused contact dermatitis to the local human population.    revista vol 13 nº 2.indd Las floraciones de la cianobacteria Microcystis son regulares y recurrentes en la laguna de los Patos y su estuario (RS). Aunque el primer registro científico fue datado en 1987, informaciones de antiguos moradores de las márgenes indican que las floraciones de cianobacterias ocurren desde el inicio del siglo pasado. Durante los meses de verano y otoño las grandes floraciones de M. aeruginosa parecen estar asociadas al flujo de crecidas del estuario, con condiciones N:P entre 10:1 a 16:1 y a temperaturas medias del agua por encima de los 20ºC. Este flujo más lento de descarga de las aguas superficiales permite diversos ciclos de crecimiento de Microcystis y el efecto de la sal marina interfiere en la composición intra y extracelular de microcistinas en las células. En el verano de 1995, una cepa RST9501 fue aislada a partir de una floración en laguna de los Patos y sus células consideradas tóxicas en bioensayos con ratones, microcrustaceos y camarones. La cepa posee cuatro variantes de microcistinas siendo la principal D-Leu1 MCyst-LR. Estas toxinas también fueron acumuladas por mariscos marinos de las playas del Atlántico Sur y por peces de agua dulce. La toxicidad de las microcistinas de esta cepa ha sido evaluada a través de test que demostraron estrés oxidativo en poliquetos y congrejos marinos a través de interferencia en la osmorregulación de peces. Las microcistinas aisladas del lago dos Patos fueron consumidas por bacterias heterotróficas del género Burkholderia. Las floraciones también producen endotoxinas (LPS) presentes en cantidades proporcionales a las células de Microcystis y han causado problemas de irritación de la piel por contacto en bañistas de la región.  Florações da cianobactéria Microcystis são regulares e recorrentes na lagoa dos Patos e seu estuário (RS). Embora o primeiro registro científico seja datado de 1987, informações de antigos moradores das margens indicam que as florações de cianobactérias existem desde o inicio do século passado. Durante os meses de verão e outono as grandes florações de M. aeruginosa aparecem e estão associadas ao fluxo de enchente do estuário, a condições N:P entre 10:1 a 16:1 e a temperaturas médias da água acima de 20ºC. Este fluxo mais lento de descarga das águas de superfície permite diversos ciclos de crescimento de Microcystis e o efeito do sal marinho interfere na composição intra e extracelular de microcistinas. No verão de 1995 a cepa RST9501 foi isolada a partir de uma floração na lagoa dos Patos e suas células consideradas tóxicas em bioensaios com camundongos, microcrustáceos e camarões. A cepa possui quatro variantes de microcistinas sendo a principal a D-Leu1 MCyst-LR. Estas toxinas foram também acumuladas por mariscos marinhos das praias do Atlântico Sul e por peixes de água doce. A toxicidade das microcistinas desta cepa tem sido avaliada através de testes que demonstraram estresse oxidativo em poliquetas e caranguejos marinhos e através de interferência na osmore­gulação de peixes. As microcistinas isoladas da lagoa dos Patos são consumidas por bactérias heterotróficas do gênero Burkholderia. As florações também produzem endotoxinas presentes em quantidades proporcionais às células de Microcystis e tem causado problemas de irritação de pele por contato em banhistas na região.

OCORRÊNCIA DE CIANOBACTÉRIAS PRODUTORAS DE TOXINAS NO RIO DOS SINOS (RS) ENTRE OS ANOS DE 2005 E 2008

revista vol 13 nº 2.indd Cyanobacteria are widely distributed autotrophic prokaryotic microorganisms, whose blooms depend on ideal amounts of nitrogen and phosphorous as well optimal temperature and pH conditions. Cyanobacterial blooms in the Sinos River, Rio Grande do Sul state, Brazil, are triggered by the influx of household and industrial wastes. The present study aimed at monitoring the occurrence of cyanobacteria in the Sinos River and tracking the water quality for human consumption. Water samples were taken from February 2005 to March 2008 at the Alberto Pasqualine Oil Refinery in the municipality of Esteio, Rio Grande do Sul state, totaling 64 samples. The different genera of cyanobacteria found were identified and counted in the laboratory in Sedgewick-Rafter chambers. The genera Planktothrix and Cylindrospermopsis, as well as an unidentified unicelular cyanobacterium were the most frequently found in the samples. Planktothrix sp. achieved 87,009 cells.mL-1 in March 2005, Cylindrospermopsis sp. achieved 65,100 cells.ml-1 in August 2006, and the unidentified unicellular cyanobacterium achieved 20,000 cells.mL-1 in January 2006. Only six samples contained no cyanobacteria. Planktothrix and Cylindrospermopsis are potentially toxic, but cyanotoxins could not be detected in the samples containing more than 20,000 cells.mL-1. Cylindrospermopsis sp, were most numerous during seasonal floods of the Sinos River (over March, June and August) whereas Planktothrix sp. were most numerous during the drought periods (January, February and March). The presence of each predominant cyanobacterium may be correlated with direction of the water flow in Lake Guaíba--Sinos River system.revista vol 13 nº 2.indd Las cianobacterias son microorganismos procariotes y autotróficos que viven en distintos hábitats. El nitrógeno y el fósforo, así como condiciones adecuadas de temperatura y pH en el agua, pueden dar lugar a la formación de floraciones. En el río dos Sinos (RS), la contaminación por efluentes domésticos e industriales estimula la ocurrencia de floraciones. Este trabajo tiene como objetivo monitorear la ocurrencia de cianobacterias en el río dos Sinos, siguiendo las normas de potabilidad de agua para consumo humano. Las colectas fueron realizadas desde febrero del 2005 hasta marzo del 2008, en la zona de captación de la refinería Alberto Pasqualine S/A en Esteio (RS), haciendo un total de 64 muestreos. En laboratorio, los géneros de cianobacterias fueron identificados y luego cuantificados en una cámara Sedgewick-Rafter. Los géneros Planktothrix, Cylindrospermopsis y una cianobacteria unicelular fueron los de mayor ocurrencia. Planktothrix sp. presentó el valor más alto de 87.009 células mL-1 en marzo del 2005; Cylindrospermopsis sp. llegó a 65.100 células mL-1 en agosto del 2006 y una cianobacteria unicelular 20.000 células mL-1 en enero del 2006. Sólo en 6 muestreos no se hallaron células de cianobacterias en el agua del río dos Sinos. Los dos géneros predominantes Planktothrix y Cylindrospermopsis son potencialmente tóxicos, pero no se encontraron cianotoxinas en el agua tratada cuando los conteos de células sobrepasaron las 20.000 células mL-1 en el agua sin potabilizar. Se constató una mayor concentración de células de Cylindrospermopsis sp. durante las crecidas del río dos Sinos (mayo, junio y agosto) y de Planktothrix sp durante el estiaje (enero, febrero y marzo). Habría la posibilidad de que este relacionada la presencia predominante de una u otra cianobacteria con el sentido de flujo en el sistema que forman el lago Guaiba y el río dos Sinos.Cianobactérias são microorganismos procariontes e autotróficos encontrados em diversos habitats. A disponibilidade de nitrogênio e fósforo e de condições ideais de temperatura e de pH nas águas favorecem as florações. No rio dos Sinos (RS), a contaminação por efluentes domésticos e industriais estimulam as florações. Este trabalho teve como objetivo o monitoramento da ocorrência de cianobactérias no rio dos Sinos, seguindo normas de potabilidade de água para consumo humano. As coletas foram realizadas de fevereiro de 2005 a março de 2008, na captação da Refinaria Alberto Pasqualine S/A em Esteio (RS), totalizando 64 amostragens. Em laboratório, foram identificados os gêneros de cianobactérias e quantificados em câmara de Sedgewick-Rafter. Os gêneros Planktothrix, Cylindrospermopsis e uma cianobactéria unicelular foram os de maior ocorrência. Planktothrix sp. apresentou o valor mais alto de 87.009 células mL-1 em março de 2005, enquanto Cylindrospermopsis sp. alcançou 65.100 células mL-1 em agosto de 2006 e uma cianobactéria unicelular, 20.000 células mL-1 em janeiro de 2006. Somente em seis amostragens não foram encontradas células de cianobactérias nas águas do rio dos Sinos. Os dois gêneros predominantes Planktothrix e Cylindrospermopsis, são potencialmente tóxicos, mas não foram encontradas cianotoxinas na água tratada quando as contagens ultrapassaram a 20.000 células mL-1 na água bruta. Constatou-se uma maior concentração de células de Cylindrospermopsis sp. durante a cheia do rio dos Sinos (maio, junho e agosto) e de Planktothrix sp. durante a estiagem (janeiro, fevereiro e março). Há possibilidade de relacionar-se a presença de uma ou outra cianobactéria predominante com o sentido do fluxo no sistema lago Guaíba -- rio dos Sinos

Environmental Variability and Cyanobacterial Blooms in a Subtropical Coastal Lagoon: Searching for a Sign of Climate Change Effects

Cyanobacterial blooms in marine and freshwater environments may be favored by shifts in physical water column parameters due to warming under climate change. The Patos Lagoon (PL), a subtropical coastal environment in southern Brazil, is known for recurrent blooms of Microcystis aeruginosa complex (MAC). Here, we analyze the variability of these blooms and their relation to changes in wind direction and speed, rainfall and freshwater run-off from 2000 to 2017. Also, we discuss both longer time-series of air temperature and rainfall and a review of local studies with microcystins produced by these noxious species. Since the 1980s, MAC blooms were associated to negative anomalies in annual precipitation that occur during La Niña periods and, in the last years (2001–2014), accompanied by a trend in low river discharge. MAC blooms were conspicuous from December to March, i.e., austral summer, with massive patches seen in satellite images as for 2017. We suggest that low rainfall and run-off years under NE wind-driven hydrodynamics might accumulate MAC biomass in the west margin of the PL system. In contrast, a positive, long-term trend in precipitation (from 1950 to 2016; slope = 3.9868 mm/yr, p < 0.05) should imply in high river discharge and, consequently, advection of this biomass to the adjacent coastal region. Due to the proximity to urban areas, the blooms can represent recreational and economic hazards to the region

Growth Characteristics of an Estuarine Heterocystous Cyanobacterium

A new estuarine filamentous heterocystous cyanobacterium was isolated from intertidal sediment of the Lagoa dos Patos estuary (Brazil). The isolate may represent a new genus related to Cylindrospermopsis. While the latter is planktonic, contains gas vesicles, and is toxic, the newly isolated strain is benthic and does not contain gas vesicles. It is not known whether the new strain is toxic. It grows equally well in freshwater, brackish and full salinity growth media, in the absence of inorganic or organic combined nitrogen, with a growth rate 0.6 d-1. Nitrogenase, the enzyme complex responsible for fixing dinitrogen, was most active during the initial growth phase and its activity was not different between the different salinities tested (freshwater, brackish, and full salinity seawater). Salinity shock also did not affect nitrogenase activity. The frequency of heterocysts was high, coinciding with high nitrogenase activity during the initial growth phase, but decreased subsequently. However, the frequency of heterocysts decreased considerably more at higher salinity, while no change in nitrogenase activity occurred, indicating a higher efficiency of dinitrogen fixation. Akinete frequency was low in the initial growth phase and higher in the late growth phase. Akinete frequency was much lower at high salinity, which might indicate better growth conditions or that akinete differentiation was under the same control as heterocyst differentiation. These trends have hitherto not been reported for heterocystous cyanobacteria but they seem to be well fitted for an estuarine life style

Antimicrobial, Cytotoxic and Antioxidant Activities and Determination of the Total Tannin Content of Bark Extracts Endopleura uchi

Endopleura uchi is a typical Amazonian tree and its bark is popularly employed in the preparation of teas against myomas, arthritis, influenza, diarrhea and cancer. In this study, the antioxidant activity, cytotoxicity and antimicrobial activity of five different extracts of the bark, selected by their total tannin content, were assessed. The potential antioxidant activity of the extracts was determined by 2.2-diphenyl-1-picrylhydrazyl radical scavenging assay and the values found were very similar among the extracts and to the standards antioxidants used in the tests. Cytotoxicity analysis in mammalian cells indicated that all the tested extracts exhibited IC50 values higher than the highest concentration used, showing that they do not present a risk when consumed under these conditions. Extract tested against five bacterial strains and one yeast strain did not show satisfactory growth inhibitory activity, and even the extracts that showed some antimicrobial activity were not effective at any dilution to determine the minimum inhibitory concentration. The results may serve as a reference for subsequent works, since such reference values described in the literature for the bark of E. uchi

Nitrogen-fixing blue-green algae from the Lagoa dos Patos estuary, RS: laboratory experiments on culture

Heterocystous blue-green algae grow regularly well in a nitrogen media, but not the non-heterocysts species. This work aimed to identify the ideal combination of culture media and illumination pattern with species collected in Patos Lagoon, RS. We tested the growth of heterocystous blue-greens and non-heterocystous species in a nitrogen-free (ASM-1 and VB-S) and a nitrogen media (VB). Under conditions of a shade illumination or alternated light and dark cycles, it showed a growth in the VB-S medium as it did in the VB medium, under any illumination pattern. Then, a proeminent growth of blue-greens, heterocystous or not, may be achieved using nitrogen-free medium, when incubated under illumination conditions which enable the non-heterocystous species to use their protection mechanisms against photosynthetic O2 like the alternated cycles of 12 hs light and 12 hs dark.Algas cianofíceas heterocísticas desenvolvem-se em meios minerais sem nitrogénio incorporado, porém as não heterocísticas não. Realizamos este trabalho no intuito de estabelecer as combinações ideais entre os meios de cultivo e condições de iluminações com espécies coletadas na Lagoa dos Patos, RS. Testamos o crescimento de cianofíceas heterocísticas ou não em meios minerais sem N incorporado (ASM-1) e com N incorporado (VB). Obtivemos que em condições de iluminação difusa ou de ciclos alternados, o crescimento ocorre no meio VB-S como ocorre da mesma forma no meio VB sob qualquer condição de iluminação. Deste modo concluímos que pode-se obter um bom crescimento de cianofíceas fixadoras de N2 heterocísticas ou não, utilizando-se meios de cultivo sem compostos nitrogenados. Basta apenas que estes sejam incubados em condições de luz onde as cianofíceas, principalmente as não heterocísticas, possam utilizar os seus mecanismos naturais de proteção contra o 0 2 fotossintético, como as do ciclos de 12 hs de luz, 12 hs de escuro