Occurrence and toxicity of Microcystis aeruginosa (Cyanobacteria) in the Paraná River, downstream of the Yacyretá dam (Argentina)

Cyanobacteria constitute the main toxin producers in inland water ecosystems and have extensive global distribution. The presence of hepatotoxins in aquatic environments is hazardous to human and animal health; even though the presence and identification of hepatotoxic microcystins in rivers and reservoirs of the world have been confirmed by several studies in the last few years. Herein, we studied the abundance and toxicity of Microcystis aeruginosa in the Argentine section of the Paraná River at the beginning of the Middle Paraná (Corrientes Hydrometer), near Corrientes city (27º28´ S - 58º51´ W) and approximately 220 km downstream of the Yacyretá dam (High Paraná). The Paraná River basin, with a drainage area of 3.1 x 106 km2 and 3 965 km in length, is the second largest catchment of South America, after that of the Amazon. The Paraná River is the main source of drinking water supply for the Northeastern Argentine region. Phytoplankton samples were collected and environmental variables were measured in a monthly basis (exceptionally fortnightly), from March 2004 to June 2008. Fifty-eight samples were analyzed for phytoplankton density and biomass. Five samples were used for toxicity testing; the latter were obtained during the cyanobacteria blooms from 2005 to 2008. Phytoplankton counts were performed with an inverted microscope, and biomass was expressed as biovolume. Bioassays with mice and high-performance liquid chromatography (HPLC) analysis were performed to evaluate the presence of cyanotoxins. Phytoplankton mainly consisted of Cryptophyta, Chlorophyta and Bacillariophyta. Microcystis aeruginosa was identified during the warmer months each year (November to March). Density varied between 189 and 25 027 cells/mL (1-10 colonies/mL) and biomass from 0.34 to 44 mm3/L. Taking into account the number of cells, the highest abundance occurred in April 2004 (25 027 cells/mL), coinciding with the largest biovolume (44 mm3/L). All mice subjected to intraperitoneal injections with samples obtained during bloom episodes showed positive results for the presence of hepatotoxins. Three microcystins variants: LR, RR and [D-Leu1] Mcyst-LR were detected by analysis with semi-preparative high-performance liquid chromatography with diode array detector system (HPLC-PDA). This constitutes the first report of microcystins recorded during M. aeruginosa blooms in the Argentine stretch of the Paraná River at the beginning of the Middle Paraná (Corrientes Hydrometer), approximately 220 km downstream of the Yacyretá dam (High Paraná).Fil: Forastier, Marina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Zalocar, Yolanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Andrinolo, Dario. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Exactas; ArgentinaFil: Domitrovic, Hugo Alberto. Universidad Nacional del Nordeste. Facultad de Ciencias Veterinarias; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Efecto de las fluctuaciones del nivel hidrométrico sobre el fitoplancton en tres lagunas isleñas en el área de la confluencia de los ríos Paraná y Paraguay

The phytoplankton of three island ponds (Los Pájaros, Catay and Turbia) (27°25’S; 58°45’W) in the begening of Paraná river floodplain were studied. These ponds are periodically flooded by the river. Catay pond was in pennanent contact with the riverwhile the other two were flooded during high water periods.Sampling was carried out during 1978-1980. Cell counts were madeby the U termohl method. Population density and diversity and were analyzed. Cell density were comparatively highest (1733, 2084 and 1028 ind. ml4 in Pájaros, Catay and Turbiaponds, respectively) either when hydrometric level was slowly increasing or after small flood phases. On the contrary, cell density were lowest in coincidence with strong flooding phases (83,73 and 57 ind. mi'1, respectively). Catay pond, the one which is in pennanent contact with the river showed highest both population density and diversity. During high water periods strong similarity ainong three ponds were observed.In Pájaros and Catay ponds Chlorophyceae (Monoraphidium, Schroederia and Scenedesmus), Ciyptophyceae (Cryp tomonas spp.) and Diatomophyceae A ulacoseira granúlala) were dominant. In the Turbia pond Euglenophyceae (Traclielomonasvolvocina) and Cryptophyceae (Cryptomonas spp.) were dominant.Nannoplankton represented between 60 and 90% of the total in all the studied ponds..The phytoplankton of three island ponds (Los Pájaros, Catay and Turbia) (27°25’S; 58°45’W) in the begening of Paraná river floodplain were studied. These ponds are periodically flooded by the river. Catay pond was in pennanent contact with the riverwhile the other two were flooded during high water periods.Sampling was carried out during 1978-1980. Cell counts were madeby the U termohl method. Population density and diversity and were analyzed. Cell density were comparatively highest (1733, 2084 and 1028 ind. ml4 in Pájaros, Catay and Turbiaponds, respectively) either when hydrometric level was slowly increasing or after small flood phases. On the contrary, cell density were lowest in coincidence with strong flooding phases (83,73 and 57 ind. mi'1, respectively). Catay pond, the one which is in pennanent contact with the river showed highest both population density and diversity. During high water periods strong similarity ainong three ponds were observed.In Pájaros and Catay ponds Chlorophyceae (Monoraphidium, Schroederia and Scenedesmus), Ciyptophyceae (Cryp tomonas spp.) and Diatomophyceae A ulacoseira granúlala) were dominant. In the Turbia pond Euglenophyceae (Traclielomonasvolvocina) and Cryptophyceae (Cryptomonas spp.) were dominant.Nannoplankton represented between 60 and 90% of the total in all the studied ponds

Biofertilización con cianobacterias (Nostoc sp.): efecto sobre el rendimiento del girasol (Helianthus annuus L.), en suelos del Chaco

La producción agrícola en el Chaco se realiza mayoritariamente con labranza convencional que modifica la calidad de la capa superficial de suelo. Debido a la importancia actual del cultivo de girasol, y sabiendo la baja fertilidad y estructura de estos suelos surge la necesidad de estudiar biotecnologías nuevas para mejorar la producción. Teniendo en cuenta que las cianobacterias diazotróficas, fotoautótrofas mejoran la producción vegetal, el objetivo de esta tesis fue evaluar fertilidad, estabilidad de suelos degradados y cambios ecofisiológicos en el cultivo de (Helianthus annuus L.), (girasol) biofertilizados con Nostoc sp.. Se realizaron dos ensayos, uno en invernáculo y otro en campo (en dos campañas durante 2007-2008 y 2008-2009). Los tratamientos en campo fueron: testigo; inoculado a los 15 y 30 días de la siembra; fertilizado; fertilizado e inoculado. Los tratamientos en invernáculo fueron: testigo; fertilizado; inoculado a los 15 días; inoculado a los 15 y 30 días. Los análisis ecofisiológicos de los estadíos vegetativos del cultivo de girasol, en campo, demostraron algunas variables favorables en su desarrollo durante la biofertilización con Nostoc sp.. En el año de mayor déficit hídrico (2008) se encontraron beneficios superiores en los tratamientos inoculados con respecto a los tratamientos fertilizados. En las variables de rendimiento se obtuvieron mayores resultados en el tratamiento fertilizado-inoculado en el año con menor déficit hídrico (2007). En cambio, el inoculado fue el mejor tratamiento en el año más seco (2008). En invernáculo, la biomasa presentó diferencias estadísticas a favor de los tratamientos inoculados versus el testigo. La partición de asimilados presentó diferencias estadísticas a favor de los tratamientos fertilizados e inoculados. En campo, la inoculación con Nostoc sp.. no modificó las variables evaluadas en suelo. En tratamientos inoculados, en el análisis microscópico del suelo se observó el desarrollo de exopolisacáridos (EPS). En las muestras de invernáculo se registró Nostoc sp... en observaciones al ML y al MEB

Contribución al conocimiento limnológico del Río Paraguay en su tramo inferior

The main limnological feactures of the Paraguay river have been studied in two sampling sites: La Herradura and Puerto Bermejo stations. The former is situated above the confluence with the Bermejo river and the latter is located below the confluence. The phytoplankton community has been dominated by Diatomophyceae (mainly Melosira granulala) and Chlorophyceae (mainly Monoraphídium, Schroederia and Scenedesmus). Crytophyceae (Cryptonomas) and Dinophyceae (Perldlnium) have always been present in low percentage. Cyanophyceae have usually been less than 4% of the total population density. In the low water period of the summer 1978-1979, the maximun phytoplankton density was estimated in 4 000 ind./ml and the production in 750 mg C/m2 d. During the flood period of May through October the lowest phytoplankton density (160 ind./ml) and production (60 mg C/m2 d) were measured. Variations in the suspended solid content and salinity of the water are discussed in relation to the hidrologic regime of the river. The huge amount of sedimenta carried by the Bermejo river to the lower Paraguay produces a drastic decrease in the transparency, phytoplankton density and production of the waters. On the other hand, conductivity, suspended solids and nutrients are highly increased.The main limnological feactures of the Paraguay river have been studied in two sampling sites: La Herradura and Puerto Bermejo stations. The former is situated above the confluence with the Bermejo river and the latter is located below the confluence. The phytoplankton community has been dominated by Diatomophyceae (mainly Melosira granulala) and Chlorophyceae (mainly Monoraphídium, Schroederia and Scenedesmus). Crytophyceae (Cryptonomas) and Dinophyceae (Perldlnium) have always been present in low percentage. Cyanophyceae have usually been less than 4% of the total population density. In the low water period of the summer 1978-1979, the maximun phytoplankton density was estimated in 4 000 ind./ml and the production in 750 mg C/m2 d. During the flood period of May through October the lowest phytoplankton density (160 ind./ml) and production (60 mg C/m2 d) were measured. Variations in the suspended solid content and salinity of the water are discussed in relation to the hidrologic regime of the river. The huge amount of sedimenta carried by the Bermejo river to the lower Paraguay produces a drastic decrease in the transparency, phytoplankton density and production of the waters. On the other hand, conductivity, suspended solids and nutrients are highly increased

Cyanobacteria y cianotoxinas en una laguna somera del nordeste de Argentina

El objetivo de este trabajo fue analizar las variaciones temporales del fitoplancton e identificar y cuantificar las cianobacterias y cianotoxinas de la laguna Aeroclub (27º28'S-58º43'W), entre octubre de 2005 y mayo de 2008. La densidad del fitoplancton osciló entre 59 y 7113 ind.mi- 1 y estuvo representado por ocho grupos taxonómicos, con dominancia de Cyanobacteria > Chlorophyceae > Cryptophyceae. Las cianobacterias predominaron durante la mayor parte del estudio ( 48% de los muestreos) con un rango de variación entre 3 (25-10-07) y 67 41 ind.ml" 1 ( 17-03-06). Su densidad presentó correlación estadísticamente significativa con la temperatura del agua (r,= 0,511; p < 0,05; g.l. = 56). La identificación de cianotoxinas se realizó con material concentrado de Microcystis aeruginosa (Kütz.) Kütz. y M. wesenbergii (Kom.) Kom. Los resultados del análisis en HPLC mostraron cuatro variantes de microcistinas: LR, RR, YR y [D-Leu1] LR. Durante el estudio, en tres ocasiones Microcystis (M. aeruginosa + M. wesenbergii) superaron el límite máximo establecido por la OMS para un Nivel de alerta I (20000 cél.ml" 1). Debido a la escasa acción antrópica en suelos circundantes de la laguna y, la baja concentración de nutrientes detectada en sus aguas, es posible que las floraciones de cianobacterias no superen este nivel de alerta. Sin embargo, cambios en sus niveles tróficos u otras modificaciones antrópicas podrían alterar el actual equilibrio ecológico.The objective of this study was to analyze the temporal variations of phytoplankton and identify and quantify Cyanobacteria and cyanotoxins of the Aeroclub lagoon (27º28'S, 58º43'W), between October 2005 and May 2008. Density ofphytoplankton ranged between 59 and 7,113 ind.ml"' and was represented by eight taxa, with dominance of Cyanobacteria &gt; Chlorophyceae &gt; Cryptophyceae. Cyanobacteria predominated during most of the study ( 48% of samples) with a range of variation between 3 (10-25-07) and 6,741 ind.m1" 1 (03-17-06). lts density showed statistically significant correlation with water temperature (rs = 0.511, p &lt; 0.05, d.f.= 56). The identification of cyanotoxins was performed with concentrated material Microcystis aeruginosa (Kütz.) Kütz. and M. wesenbergii (Kom.) Kom. The results of HPLC analysis showed four variants of microcystins LR, RR, YR and [DLeu'] LR. During the study, three times Microcystis (M. aeruginosa + M. wesenbergii) exceeded the maximum lirnit set by the WHO for I alert level (20,000 cel.mi- 1). Due to the lirnited human action in the lagoon surrounding soils and low nutrient concentrations detected in its waters, it is possible that cyanobacterial blooms do not exceed this level of alert. However, changes in their trophic levels or other anthropogenic modifications could alter the current ecological balance.Facultad de Ciencias Exacta

Cyanobacteria y Cianotoxinas en una laguna somera del Nordeste de Argentina

El objetivo de este trabajo fue analizar las variaciones temporales del fitoplancton e identificar y cuantificar las cianobacterias y cianotoxinas de la laguna Aeroclub (27º28'S-58º43'W), entre octubre de 2005 y mayo de 2008. La densidad del fitoplancton osciló entre 59 y 7113 ind.m1· 1 y estuvo representado por ocho grupos taxonómicos, con dominancia de Cyanobacteria &gt; Chlorophyceae &gt; Cryptophyceae. Las cianobacterias predominaron durante la mayor parte del estudio (48% de los muestreos) con un rango de variación entre 3 (25-10-07) y 6741 ind.ml-1 (17-03-06). Su densidad presentó correlación estadísticamente significativa con la temperatura del agua (r,= 0,511; p &lt; 0,05; g.l. = 56). La identificación de cianotoxinas se realizó con material concentrado de Microcystis aeruginosa (Kütz.) Kütz. y M. wesenbergii (Kom.) Kom. Los resultados del análisis en HPLC mostraron cuatro variantes de microcistinas: LR, RR, YR y [D-Leu1] LR. Durante el estudio, en tres ocasiones Microcystis (M. aeruginosa + M. wesenbergii) superaron el límite máximo establecido por la OMS para un Nivel de alerta I (20000 cél.ml- 1 ). Debido a la escasa acción antrópica en suelos circundantes de la laguna y, la baja concentración de nutrientes detectada en sus aguas, es posible que las floraciones de cianobacterias no superen este nivel de alerta. Sin embargo, cambios en sus niveles tróficos u otras modificaciones antrópicas podrían alterar el actual equilibrio ecológico

Aspectos ecológicos de la ficoflora de ambientes acuáticos del Chaco Oriental (Argentina)

The present study describes the al gal flora of some streams and tropical swamps ("esteros") settled in the Eastern Chaco between the Pilcomayo&nbsp;(25°15'S; 57°45'W) and Amores (28°15'S; 59°30'W) rivera towards the Paraguay-Paraná axis. Samples taken during 1984 at different hydrometric levels within the annual hydrologic re gime, were compared. The quali and quantitative study of the phytoplankton was carried out, as well as the periphytic flora from natural substrates with addition of SEM analyses. Counts of phytoplankton were done by the Utermohl method. Phytoplankton density was low during the high water period (between 15 and 280 ind.ml-1), and high species richness were found. During the low water period the phytoplankton density ranged from 20 to 1746 ind.ml-1. The highest density was recorded in highly salinitized water bodies with blooms of halophilous species (Glenodinium balticum and Protoperidinium achromaticum).&nbsp; In response to high salinity and alkalinity diatoms such as Nitzschia acicularis var. closterioides, Surirella striatula, Campylodiscus clypeus and Bacillaria paradoxa were found in the phytoplankton. Besides, Audouinella sp. (Rhodophyta) and Enteromorpha sp. (Chlorophyta) were observed in the periphyton. In the tropical swamps the phytoplankton density ranged from 22 to 525 ind.ml-1 with high species number of Euglenophyta. Acidity indicators species (within Chrysophyceae, Xanthophyceae and Diatomophyceae) were recorded in the periphyton. Thus, local populations showed strong differences with respect to other regional waterbodies of the Northeastem of Argentina.The present study describes the al gal flora of some streams and tropical swamps ("esteros") settled in the Eastern Chaco between the Pilcomayo&nbsp;(25°15'S; 57°45'W) and Amores (28°15'S; 59°30'W) rivera towards the Paraguay-Paraná axis. Samples taken during 1984 at different hydrometric levels within the annual hydrologic re gime, were compared. The quali and quantitative study of the phytoplankton was carried out, as well as the periphytic flora from natural substrates with addition of SEM analyses. Counts of phytoplankton were done by the Utermohl method. Phytoplankton density was low during the high water period (between 15 and 280 ind.ml-1), and high species richness were found. During the low water period the phytoplankton density ranged from 20 to 1746 ind.ml-1. The highest density was recorded in highly salinitized water bodies with blooms of halophilous species (Glenodinium balticum and Protoperidinium achromaticum).&nbsp; In response to high salinity and alkalinity diatoms such as Nitzschia acicularis var. closterioides, Surirella striatula, Campylodiscus clypeus and Bacillaria paradoxa were found in the phytoplankton. Besides, Audouinella sp. (Rhodophyta) and Enteromorpha sp. (Chlorophyta) were observed in the periphyton. In the tropical swamps the phytoplankton density ranged from 22 to 525 ind.ml-1 with high species number of Euglenophyta. Acidity indicators species (within Chrysophyceae, Xanthophyceae and Diatomophyceae) were recorded in the periphyton. Thus, local populations showed strong differences with respect to other regional waterbodies of the Northeastem of Argentina

Effect of fluctuations in water level on phytoplankton development in three lakes of the Paraná river floodplain (Argentina)

The effect of fluctuations in water level on phytoplankton development (abundance, biomass, size structure, taxonomic composition, species diversity and rate of community compositional change) in three vegetated lakes of the Paraná River floodplain (27° 27′ S; 58° 55′ W) were studied. Between September 1995 and June 1996 there were two inputs of lotic water. Ordering of physical and chemical parameters (Principal Component Analysis) allowed the differentiation of two phases: I) without lotic influence (limnophase) and II) with lotic influence (potamophase). Two-hundred fifty-eight algal taxa were identified, of which Euglenophyceae showed the highest number of taxa (65% of total). Small Chlorophyceae and Cryptophyceae (C-strategists) predominated in density in both periods. During potamophase, the input of nutrients from a flood event produced an increase in algal biomass and a shift in phytoplankton composition from a Chlorophyceae (C-strategists), to a Cyanophyceae and Euglenophyceae (S-strategists), dominated comunity. Bacillariophyceae, Chrysophyceae, Dinophyceae and Xanthophyceae were best represented during limnophase. All phytoplankton attributes showed significant differences between phases (limnophase vs potamophase) but not among lakes. These results support the hypothesis that hydrology (floods) clearly exerts an overall impact on the phytoplankton community composition in lakes of the Paraná River floodplain. Hydrology effects the lake water chemistry, conditioned by the isolation time prior to a flood, the horizontal dragging and exchange of algae during floods, and the water residence time and aquatic vegetation coverage.Fil: Zalocar, Yolanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentin

Phytoplankton biodiversity in Paraguay-Paraná rivers

Phytoplankton biodiversity in Paraguay-Paraná hydrographic basin was analized, including Paraguay and Paraná rivers and its floodplain. This contribution is based upon information published in taxonomic and ecological papers and the autor’s unpublished data. The phytoplankton community was structured by aproximately 800 taxa belonging (among Divisions and Classes) to eight taxonomics groups: Chlorophyta, Bacillariophyceae, Euglenophyta, Cryptophyta, Cyanophyta, Xanthophyceae, Chrysophyceae and Dinophyta. Five hundred ninety three taxa were registered in the river (principal channel) and 761 in the floodplain. In the river, species richness showed a decrease in North-South direction with a higher number of taxa in the Pantanal. Chlorococcales (Chlorophyta) was the Order with greater species richness (in both river and floodplain). It’s followed by Bacillariophyceae in the river and by Euglenophyta in the floodplain. The contribution of each taxonomic group to the abundance and species richness is different and may varie in the principal channel of the river and in the floodplain in relation to hidrossedimentological regimeFil: Zalocar, Yolanda. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; Argentin