Protected areas: A focus on Brazilian freshwater biodiversity

Brazil has a variety of aquatic ecosystems and rich freshwater biodiversity, but these components have been constantly damaged by the expansion of unsustainable activities. An array of different conservation strategies is needed, especially the creation of protected areas (PAs, hereafter). However, Brazil's PAs are biased towards terrestrial ecosystems and we argue that current PAs have limited efficacy in the protection of freshwater biodiversity. New PAs should better consider aquatic environments, covering entire basins, rivers and other freshwater habitats. We recommend ways to implement these PAs and provide guidance to avoid social impacts. Freshwater systems in Brazil provide essential goods and services but these ecosystems are being rapidly degraded and will be lost if not adequately protected. © 2018 The Authors. Diversity and Distributions Published by John Wiley & Sons Lt

Deficient downstream passage through fish ladders: the case of Peixe Angical Dam, Tocantins River, Brazil

Downstream passage through fish ladders and other facilities remains largely uninvestigated in South America. In view of this concern, we monitored ascending and descending fish movements through the fish ladder at Peixe Angical Dam, upper Tocantins River, Brazil, between September 2009 and August 2010. To investigate the extent of downstream passage, the fish fauna was sampled monthly (i) at sites upstream and downstream from the dam and (ii) inside the ladder. To distinguish between ascending and descending movements, the fish ladder remained open (permanent water flow), but a screen blocked the complete passage of fish in both directions. The results of the study indicated that the ladder restricts fish movements in both directions. Few species were found to use the ladder (31 out of 119 species recorded in the area). Moreover, monitoring revealed that downstream passage is even more limited. Only 18 species were recorded moving downstream. In addition, few fish attempted to move downstream during the year; of all fish captured in the ladder (n = 17,335), only 4% were descending. Species performing exclusive downstream movements were numerically rare or infrequent. Most downstream captures involved only four species. We emphasize that several species performed one-way upstream movements or showed a high density of ascending fish. Consequently, the numerical ratio between ascending and descending fish (ind./m²) showed high positive values throughout the year (644:1 on average, considering all species); migratory species showed higher ratios (1069:1). The results of the study show that the facility fails to support the downstream passage of migratory and non-migratory fishes. We conclude that the fish ladder at Peixe Angical Dam does not play a conservation role and may complicate alternative conservation efforts

Distribution of aquatic macrophytes along depth gradients in Lajeado Reservoir, Tocantins River, Brazil

Abstract Aim The present study investigated the diversity of aquatic macrophytes in the littoral zone of Lajeado Reservoir, Tocantins River. We characterized spatial variations in species richness, composition and abundance along depth gradients. Methods Macrophyte sampling occurred at the end of the dry season (September and October 2014) in four sites of the reservoir. We established transects perpendicular to the shoreline, each 25 m long, divided in 3 sections (plots of 5 x 5 m). Results In total, we recorded 18 taxa of aquatic macrophytes, belonging to nine families and four life forms. Najas microcarpa, Echinodorus tenellus. and Chara sp. were the more frequent and abundant taxa. Considering depth gradients, we recorded 18 taxa in the section closer to the shoreline, 13 in the middle section and 10 in the section more distant to the shoreline. Submerged and emergent species were more frequent and abundant, especially in the section close to the shoreline; epiphytes and free-floating species were rare. Plot species richness (total, emergent and submerged) decreased along the gradient, and a Non-Metric Multidimensional Scaling (NMDS) revealed that the plot close to the shoreline had different composition when compared to adjacent sections. Individual species showed particular behaviors, but most tended to decline in abundance and occurrence along the gradient. Conclusions The present study revealed that small-scale environmental gradients affect the distribution of aquatic plants in Lajeado Reservoir, with greater diversity in habitats close to the shoreline

Morphometric and biotic variables as potential predictors of

Reservoirs cause hydrological changes (i.e., water level stabilization) that favor the colonization of aquatic macrophytes. Knowing the ecological factors that determine the occurrence of these plants is critical for water management (e.g., plant control) and biodiversity conservation. In this sense, the present study investigated colonization patterns of Ludwigia sedoides in Lajeado reservoir (Tocantins River, Amazon Basin), in order to identify variables that influence colonization at habitat scale. We investigated the relationship between colonization (coverage area and occurrence) and morphometric (fetch, slope, depth and distance from shoreline) and biotic variables (local diversity of macrophytes and co-occurrence patterns). Stepwise regression selected fetch, depth and slope as the best variables to explain the variation in L. sedoides coverage, which together explained 46% of data variability. Fetch and slope were negatively correlated with coverage, whereas depth showed a positive correlation. No biotic variable was included in the model (P>0.05). However, the investigation of the geometric shape of bivariate correlations (null models) showed positive relationships with local species richness and richness of life forms (i.e., submerged, emergent, floating and epiphytic). In addition, an analysis of species co-occurrence (C-score) revealed that L. sedoides is negatively associated with some macrophyte species. We believe, however, that these results may be associated with species preferences for particular environmental conditions. In conclusion, the present study indicated that morphometric variables are potential predictors of the colonization of L. sedoides in Lajeado reservoir. Sheltered sites with low slope and moderate depths represent favorable environment for colonization and growth.Ludwigia sedoides is an aquatic macrophyte commonly found in Neotropical reservoirs, but little is known about the factors determining its distribution. The present study is the first to indicate that morphometric variables are potential predictors of L. sedoides. Sheltered sites with low slope and moderate depths represented favorable environments for colonization and growth