10 research outputs found
Estudio de la dieta folívora del mono aullador negro (Alouatta caraya) mediante el empleo del método de análisis microscópico de las heces
Fil: Bazzalo, Mariel. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales; Argentina
Uso de h\ue1bitat y principales comportamientos del delf\uedn gris (Sotalia guianensis, Van B\ue9n\ue9den, 1864) en la Bah\ueda Norte, estado de Santa Catarina, Brasil
Reações comportamentais na superfície de Sotalia guianensis (Cetacea, Delphinidae) durante encontros com embarcações na Baía Norte de Santa Catarina
Reações comportamentais na superfície do golfinho ou boto-cinza (Sotalia guianensis) a embarcações foram estudadas dentro e no entorno de uma área protegida no Sul do Brasil (27°35’S, 48°30’W) durante os anos de 1993 a 2003. A maioria dos encontros embarcação-golfinho causaram reações negativas e apenas 0.03% (n = 2) produziram reações positivas, enquanto 35.45 (n = 235) não resultaram em reações. As reações comportamentais dos animais demonstraram padrões de freqüência distintos entre si ao longo dos anos, com freqüência decrescente de reações negativas e, crescente das neutras. As reações dos golfinhos foram afetadas por estação do ano, tipo de embarcação e tipo de aproximação da embarcação. A maioria dos encontrosocorreu no verão, embora tenham sido registrados ao longo de todas as estações do ano. Escuna foi o tipo de embarcaçãoresponsável pelo maior número de encontros, seguida por barcos de passeio e por barcos de pesca. Praticamente todos os encontros geo-referenciados ocorreram dentro da área protegida, sendo 60% no interior da Zona Exclusiva para Golfinhos. Fatores importantes para reduzir o impacto da atividade das embarcações sobre esses golfinhos nesta importante área podem incluir maior integração e cooperação entre operadores de embarcações, comunidade cientifica e moradores locais, assim como fiscalização adequada da atividade das embarcações
Spatial and temporal assessment of the risk associated to bacteria in recreational waters of a large South American Reservoir
The characterization of risk due to recreational exposure to water needs to assess the concentration of pathogens in the water and the degree of contact with those pathogens. In this study we assessed the risk associated to E. coli and cyanobacteria in a large South American Reservoir heavily used for recreation, by i) gathering field environmental data from two water agencies (six sites, summers 2011-2015), ii) generating satellite data at landscape scale (750 km2, summers 2011-2017) and running a health survey related to water exposure (summer 2017). Field data showed that cyanobacteria abundances recurrently surpassed the moderate and high-risk categories across sites and year analyzed, and a significant positive link between cyanobacteria abundance and microcystin concentration. Nevertheless, microcystin concentrations were in 90% of cases mostly within the low to moderate risk categories. Mean E. coli concentrations during 2011-2015 were within the high-risk category in 30% of the sites, but in 2017, sites identified as low risk had high-risk. The latter underscores the high risk posed by E. coli in the reservoir. Cyanobacteria (cell abundance and microcystin) and coliform bacteria abundances were unrelated, suggesting different responses to environmental or anthropogenic triggers. Satellite data evidenced that the highest risk related to cyanobacteria abundance occurred in the dendritic areas of the Argentinean side of the reservoir, areas which currently remain unmonitored by water agencies. Satellite monitoring bridged the limited spatial and temporal coverage of field samplings for cyanobacteria abundance (yet not for toxicity nor E. coli abundances) and rendered a risk map at landscape scale, which can be used by water agencies to effectively monitor and manage cyanobacteria blooms, and to-coupled with exposure variables-assess health risks related to cyanobacteria. The health survey identified few numbers of suspected patients with symptoms and who bathed in the Salto Grande reservoir. At the time of exposure, sites in the environment evidenced high bacteria concentration (mostly E. coli and to a lesser extent cyanobacteria) denoting situations where aspects of the biophysical environment affect human health. More studies and integration among environmental and health disciplines are needed to assess the impacts of these water born bacteria in human health. Finally, we further assessed how well cyanobacteria quantitative proxies monitored in the field explained the outcome of a qualitative risk communication system-the cyano-traffic-light-which is ongoing since 2011. We obtained a significant predictive model only for cyanobacteria abundance, yet with low predictive value. This probably occurred because the variables used to build each cyano-traffic-light category (cyanobacteria abundance, toxicity and chlorophyll-a, scums) were monitored with different frequencies, and because at least two of these variables needed to surpass the threshold of each category to be allocated into a risk category. Based upon our results we propose several modifications to the current cyano-traffic-light, that believe would better reflect what happens in the field and protect human health: i) include E. coli concentration and satellite estimated cyanobacteria abundance (mostly in areas not covered by field monitoring), ii) relax the thresholds for cyanobacteria abundance and toxicity, and iv) base each risk category upon the surpassing of one of either E. coli, cyanobacteria abundance, microcystin.Centro Regional de Estudios Genómico
Integrating field and satellite monitoring for assessing environmental risk associated with bacteria in recreational waters of a large reservoir
In a large South American Reservoir (750 km2, limit between Uruguay and Argentina), we characterized the environmentalrisk posed by cyanobacteria proxies (abundance, toxin concentration, chlorophyll-a) andEscherichiacoli abundances, integrating field (six sites, summers 2011?2015) and satellite (750 km2, summers 2011?2017)monitoring. We further assessed how well field cyanobacteria quantitative proxies (abundance, toxinconcentration, chlorophyll-a and scum formation) used to build a local risk communication system for recreational(bathing) use of waters named ?cyano-traffic-light?, ongoing since 2011, reflected its outcome.Cyanobacteria abundance in the field ranged from moderate (>20,000 to 100,000 cells mL−1), and its abundance was positively related to toxin (microcystin) concentration. Meanmicrocystin concentrations was within the low (≤2 μg L−1, 50% sites) or moderate (>2 126 CFU 100 mL−1) for human health, mostly in the northern part of thereservoir. Cyanobacteria proxies (abundance and toxins) and E. coli abundance were, however, unrelated. Thepredictive model showed that, out of the four cyanobacteria proxies used to construct the cyano-traffic-lightonly cyanobacteria abundance (p < 0.05) explained the outcome of the reports, yet with low explanatorypower (41%). The satellite monitoring allowed delimiting the extent and magnitude of the environmental riskposed by cyanobacteria at landscape scale (highest risk in the meander parts of the Argentinean side of theFil: Gangi, Daniela. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Ecología, Genética y Evolución. Laboratorio de Limnología; ArgentinaFil: Frau, Diego. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Santa Fe. Instituto Nacional de Limnología. Universidad Nacional del Litoral. Instituto Nacional de Limnología; ArgentinaFil: Drozd, Andrea Alejandra. Universidad Nacional de Avellaneda; Argentina. Universidad Nacional de La Plata. Centro Regional de Estudios Genómicos; ArgentinaFil: Bordet, Facundo. Ministerio de Relaciones Exteriores, Comercio Internacional y Culto. Comisión Técnica Mixta de Salto Grande; ArgentinaFil: Andrade, Soledad. Ministerio de Relaciones Exteriores, Comercio Internacional y Culto. Comisión Técnica Mixta de Salto Grande; ArgentinaFil: Bazzalo, Mariel. Comision Administradora del Rio Uruguay; ArgentinaFil: de Tezanos Pinto, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; Argentin
Hyperspectral remote sensing monitoring of cyanobacteria blooms in a large South American reservoir: High-and medium-spatial resolution satellite algorithm simulation
We used hyperspectral remote sensing with the aim of establishing a monitoring program for cyanobacteria in South American reservoir. We sampled at a wide temporal (2012-2016, 10 seasons) and spatial (30km) gradient, and retrieved 111 field hyperspectral signatures, chlorophyll-a, cyanobacteria densities, and total suspended solids. The hyperspectral signatures at cyanobacteria dominated situations (n=75) were used for selecting the most suitable spectral bands in 7 high and medium spatial resolution satellites (Sentinel-2, Landsat 5, 7 and8, Spot 4/5 and6/7, WorldView 2), and for the development of chlorophyll and cyanobacteria cell abundance algorithms. The best performing chlorophyll algorithm was Sentinel 2 ((λ_560- λ_660+ λ_703)/(λ_560+ λ_660+ λ_703)) (R2 0.80), followed by WorldView 2 ((λ_550- λ_660+ λ_720)/(λ_550+ λ_660+ λ_720)) (R20.78), Landsat and SPOT series(λ_550- λ_650+ λ_800)/(λ_550+ λ_650+ λ_800) (R2 0.67-0.74). When these models were run for cyanobacteria abundance, the coefficient of determination remained rather similar, but the root mean square increased. This could affect the cyanobacteria cell abundance estimation in about 20%, yet it still allowed assessing the alert level categories for risk assessment. Our results highlight the importance of the red and near infrared region in identifying cyanobacteria in hypereutrophic waters, showed coherence with field cyanobacteria abundance, and allowed assessing bloom distribution in this ecosystem.Fil: Drozd, Andrea Alejandra. Comision Administradora del Rio Uruguay; ArgentinaFil: de Tezanos Pinto, Paula. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Botánica Darwinion. Academia Nacional de Ciencias Exactas, Físicas y Naturales. Instituto de Botánica Darwinion; ArgentinaFil: Fernandez, Virginia. Comision Administradora del Rio Uruguay; ArgentinaFil: Bazzalo, Mariel. Comision Administradora del Rio Uruguay; ArgentinaFil: Bordet, Hugo Facundo. Ministerio de Relaciones Exteriores, Comercio Internacional y Culto. Comisión Técnica Mixta de Salto Grande; ArgentinaFil: Gómez Santibáñez, Guillermo del Carmen. Comision Nacional de Actividades Espaciales; Argentin
Home ranges of Guiana dolphins (Sotalia guianensis) (Cetacea: Delphinidae) in the Cananeia estuary, Brazil
Home ranges of seven Guiana dolphins (Sotalia guianensis) (Van Beneden, 1864) were studied in the Cananeia estuary (similar to 25 degrees 03'S 47 degrees 55'W), south-eastern Brazil. Boat-based observations were conducted from May 2000 to July 2003 in similar to 132 km(2) of protected inner waters. The photo-identification technique was used to follow naturally marked individuals through time and space. From a total of 138 catalogued individuals, five males and two females presented 20+ sightings and were used for home range estimation. Sightings were plotted and analysed in a Geographic Information System (GIS). With the 'Home Range Tools' extension the fixed kernel density estimator with band width (smoothing parameter) chosen via least squares cross-validation was performed for each individual. The fixed kernel method was used to estimate the non-parametric utility distribution of each dolphin, keeping band width (h) constant for a data set. The first polygons created by these parameters had an amoeboid shape and in some cases more than one centre of activity. The 95% home range estimated outlines varied from 1.6 to 22.9 km(2) (7.9 +/- 8.3 km(2)). This large interval shows strong evidences on individual variation in S. guianensis' home ranges. Several individuals showed small home ranges when compared to other cetacean species. An overlap of home ranges of different sizes and shapes were observed for Guiana dolphins with large range movements. Centres of activity were concentrated in the main entrance of the Cananeia estuary. This was a first attempt to understand the way S. guianensis uses the Cananeia estuary and such data are essential for conservation and management purposes.Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP