Fluvial lateral environments in Río de La Plata basin: effects of hydropower damming and eutrophication

Abstract

Cite as: Debastiani Júnior, J.R. et al. Fluvial lateral environments in Río de La Plata basin: effects of hydropower damming and eutrophication. Acta Limnologica Brasiliensia, 2016, vol. 28, e26. Abstract: Aim: Identify large-scale limnological patterns in lateral water bodies of Río de La Plata Basin, considering the influence of river damming and urban conglomerates. Methods: Samplings were performed in a broad spatial scale (along 16 latitude degrees) during two seasonal periods (23 sites in summer and 20 sites in winter) for measurements of physical and chemical variables, chlorophyll a and periphyton biomass. Results: Geographical distance between sites was significantly correlated with the environmental dissimilarity (Euclidean distance). Reservoir and floodplain associated sites exhibited lower phosphorus concentration. Eutrophic conditions were higher in sites close to urban areas and regions with intensive agriculture and livestock activities, which exhibited higher conductivity, concentration of nitrogen and chlorophyll a. Sites associated to reservoirs had higher periphyton biomass. Inorganic suspended matter was higher in summer whereas organic suspended matter was higher in the winter, due to contrasting rain seasonality in the upper Paraná River sub-basin. No significant correlation between the dissimilarity of the vegetation and the environmental dissimilarity or geographical distance between sites was observed. Conclusions: The limnological conditions in the fluvial lateral habitats in the Río de La Plata basin are highly influenced by reservoirs construction, intensive urban occupation and rain seasonality.

Retrieval and mapping of chlorophyll-a concentration from Sentinel-2 images in an urban river in the semiarid region of Brazil

“…In addition, in the dry season, the reduction in flow, width and depth favour the formation of natural barriers, such as meandering curves, rocky outcrops, alluvial deposits of pebbles to sands and river islands, cause the damming of Poti River waters (Lima and Augustin, 2014). From this perspective, natural and artificial barriers, in addition to the land-use change, are the most important structural determinants for the modification of the limnological characteristics of a watershed, as they create a lentic mosaic macrosystem, very different from the original lotic condition, favourable to the processes of eutrophication (Debastiani Júnior et al, 2016). These concentrations can be explained by the location of these points, as PT-00 is located in the leastinhabited region, with preserved riparian forest and without contributions from domestic and industrial effluents, while PT-02 is located at 850 m downstream from the Alegria Sewage Treatment Plant (Mendes-Câmara, 2011).…”

Rise of toxic cyanobacterial blooms is promoted by agricultural intensification in the basin of a large subtropical river of South America

“…Some of the areas that currently experience restrictions on cultivation will become productive regions depending on supplementary irrigation by constructing dams. Dams modulate river discharge and sequester sediments (Bonachea et al, 2010; Depetris & Pasquini, 2007a), thus favoring eutrophication and allowing reproduction and accumulation of cyanobacteria, increasing their toxin production and diversity (Martínez de la Escalera et al, 2017, 2022) as reported for the upper reaches (Debastiani Júnior et al, 2016) and at the lower stretches (O'Farrell & Izaguirre, 2014) of the river. Increases in extreme precipitation events, allow rapid nutrient transport from soils into rivers (Ockenden et al, 2017) and then to dams, where blooms will continue to increase in frequency and magnitude.…”

“…Toxic cyanobacterial blooms are frequently registered in the Uruguay River (Bordet et al, 2017; Debastiani Júnior et al, 2016; O'Farrell & Izaguirre, 2014) and exported to the Río de la Plata Estuary (Kruk et al, 2017; Martínez de la Escalera et al, 2017; Nagy, Gómez‐Erache, Lopez, & Perdomo, 2002; Segura et al, 2017). These blooms negatively impact health, including human intoxications (Giannuzzi et al, 2011; Vidal et al, 2017), local economies, tourism and related recreational activities (Kruk, Martínez, et al, 2021).…”

Floración excepcional de cianobacterias tóxicas en la costa de Uruguay, verano 2019

“…En ellos, el agua enriquecida en nutrientes que corre en los ríos es retenida, generando condiciones que favorecen la acumulación de cianobacterias de gran tamaño y la ocurrencia de floraciones (Wang, et al, 2018). En estas condiciones, las cianobacterias del CMA son las más frecuentes (Reynolds, et al, 2002;Debastiani, et al, 2016;Haakonsson, et al, 2017;Adloff, et al, 2018;González-Piana, et al, 2017). Esto transforma a los embalses en fuentes potenciales de cianobacterias, que en condiciones de lluvias muy intensas pueden ser transportadas aguas abajo, distribuyendo las grandes biomasas o inoculando nuevos ecosistemas (Anderson, et al, 2018).…”

“…Los embalses y los cuerpos de agua que registran más floraciones en la Cuenca del Plata, en particular en el área de influencia de la costa de Uruguay, son aquellos cuyas cuencas de drenaje incluyen una producción agrícola intensiva (Aguilera, et al, 2018;Debastiani et al, 2016). Este es el caso de los embalses en los tributarios del Plata, como por ejemplo el río Uruguay (Salto Grande: Bordet, et al, 2017), Río Negro (González-Piana, et al, 2017) y río Paraná (Adloff et al, 2018).…”