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Water availability is an essential factor in maintaining the integrity of ecological processes and is a source of socio‐economic development. However, socio‐economic development increases the pressure on water resources. Thus, understanding the flow regime in a watershed is essential to correct water resource management. In this study, we propose using dynamic quantile regression (DQR) to analyse trends in streamflow time series. DQR is a subset of the general class of semi‐parametric quantile regression models, which is tailored for time series modelling. It allows for autoregressive dynamics and modelling of trending behaviour and seasonal fluctuations. With a single model, it is possible to estimate the impacts of predictor variables on any given quantile of the response distribution instead of simply evaluating such effects on the mean response, as is typically done in other statistical approaches. In other words, it is possible to gain knowledge on how predictors impact the magnitude of streamflow in wet (upper quantiles) and dry seasons (lower quantiles) separately. We used DQR to model a streamflow time series of 27 gauges, distributed in the Araguaia watershed in central Brazil. The results show that, except for a single gauge (Alto Araguaia), there are downward streamflow trends, thus non‐stationary behaviour. The model yielded excellent data fits (pseudo‐R2 above 0.80), and it was possible to obtain a confidence interval for each slope. In our analysis, the usefulness of DQR modelling for assessing trends in streamflow time series is shown and, consequently, for achieving efficient water resource management. [ABSTRACT FROM AUTHOR]

The Araguaia River basin corresponds to 4.53% of the Brazilian territory and is the target of an intense occupation process and environmental impacts which compromise its socio-environmental integrity. Among the various conservation and environmental preservation strategies instructed by Brazilian environmental policies, conservation units (UCs) can assist in the territorial and environmental management strategies of river basins to preserve the country's natural resources. The aim of this article is to understand the context of creation, quantity, distribution and the effectiveness of conservation units within the Araguaia River basin. We were able to identify 49 conservation units in the basin, which represents only 9.42% of its territory. These units were organized by Category (Fully Protected or Sustainable Use), Area (ha), Decree/Law of creation, presence or not of a Management Council and Management Plan, Municipalities which comprise the conservation units and the Responsible Body for administering and managing the UCs (Federal, State or Municipal). Thus, it was evidenced that the UCs are not evenly distributed in the basin area, and there is no protection - in any conservation unit category - of any of the springs of the main tributaries of the Araguaia River. Accordingly, the effectiveness of the areas is compromised by the absence of management instruments and the historical recurrence of deforestation and fires. [ABSTRACT FROM AUTHOR]

The article discusses the phylogenetic characters of the endangered genus Rondonacara hoehnei of the Cichlid fish family, which was found in the Araguaia River, Brazil and are declining in numbers due to environmental destruction.

Chlorophyll-a (Chl-a) has been widely used in the assessment and monitoring of aquatic environments. Local and regional factors can influence Chl-a concentrations; moreover, the connection between terrestrial and aquatic ecosystems is a major paradigm within aquatic ecology. Here, we investigate the spatial distribution of Chl-a concentrations in a tropical savannah floodplain in Central Brazil using a broad spatial data set (a 900-km north-south transect; 30 lakes). We determine the relative importance of local environmental variables (limnological and morphometric) and regional (land use) and spatial distances (spatial eigenvector) on Chl-a concentrations using partial linear regression. We evaluate the direct and indirect effects of local and regional variables on Chl-a with a path analysis. Our results indicate spatially autocorrelated patterns wherein lakes in closer proximity showed more similar levels of Chl-a than more distant lakes. Local environmental factors explained most variance in Chl-a (R2adj = 0.28; P = 0.02); more specifically, both lake area and total nitrogen significantly (P < 0.05) explained Chl-a concentrations (direct effects). Meanwhile, regional factors neither directly nor indirectly predicted Chl-a. Thus, internal processes, such as the resuspension of sediment (which is frequent in tropical floodplains), rather than external influences, were the main factors that explained Chl-a concentrations in this study. The importance of local variables in structuring Chl-a concentration may be used to guide the conservation of the aquatic ecosystems in these tropical floodplain lakes. [ABSTRACT FROM AUTHOR]