Major hydroelectric dams are proliferating in tropical regions such as Amazonia, where extensive new hydropower developments are planned despite potentially severe ecological and social impacts. The ...status of freshwater biota in the vicinity of existing dams could be valuable to predict the effects of such developments, but detailed ecological monitoring before and after dam construction is frequently lacking. In the absence of these data, we used a space‐for‐time replacement to compare a key component of the aquatic biota at upstream and downstream sites, with the latter more closely resembling river channel conditions prior to the dam. We assessed the fish assemblages upstream and downstream of the Coaracy Nunes Dam in Amapá, Brazil, the first ecological study at this site since this dam was constructed 42 years earlier. We used gillnets during eight bimonthly field campaigns, covering both wet and dry seasons, and sampled the ichthyofauna (1819 individuals, 81 species) at four sites: Downstream Channel, Reservoir, Upstream Lake and Upstream Channel. We found clear negative impacts on the abundance, biomass, species richness, alpha diversity and species dominance upstream of the dam. The physical subdivision of the river channel and the upstream channel conversion from lentic to lotic habitats were strongly associated with differences in the composition and structure of fish communities. Notable changes include an increased contribution of small‐bodied fish in the reservoir and an absence of long‐distance migrants upstream of the dam. Downstream channel habitats, in particular, retained their fish diversity with high conservation value typical of eastern Amazonia, yet these areas now face the threat of new hydropower development farther downstream. The long‐term impacts on aquatic biodiversity highlighted in this study are especially relevant in the face of burgeoning new hydroelectricity development plans for rivers across lowland Amazonia.
The exploitation of resources by closely related species with similar niches may be mediated by differences in activity patterns, which may vary in nycthemeral scale and seasonal scale. Piranhas ...Serrasalmus gibbus and Serrasalmus rhombeus are Neotropical predators that occur sympatrically in many environments of the Amazon basin. To evaluate the strategies adopted by these two species in a restricted environment (a reservoir), nycthemeral and seasonal samples were made, identifying the composition of the diet and their activity patterns. A total of 402 specimens were collected: 341 S. gibbus and 61 S. rhombeus. Both species fed themselves primarily on fish, with some seasonal variation being found in S. gibbus during the flood season, when plant material was consumed. There was considerable temporal overlap in the foraging behavior of the two species, although S. rhombeus presented a bimodal pattern of abundance over the 24-hour cycle. S. rhombeus was more active during the nighttime, between dusk and early morning, whereas S. gibbus was active throughout the nycthemeral cycle. These findings indicate low levels of competition between the two species, which allowed for a considerable overlap in nighttime foraging, following distinct nycthemeral patterns of foraging activity and allowing their coexistence.
The anabolic-androgenic steroids (AAS) are clinically used as an androgen replacement, in hypogonadism treatment, to induce puberty, and also in the treatment of chronic degenerative diseases. The ...AAS use out of clinical context is becoming massively, being used merely for aesthetic reasons. AAS abuse may cause severe disarrangement on the HPG axis and generate a significant decrease in testosterone synthesis and secretion by the testes. This review aims to evaluate whether the hypogonadism induced by AAS abuse is reversible and under what circumstances the reversibility is possible. For this, PRISMA guidelines and several databases are used between July and September 2020. Altogether, this systematic review identified and analysed 179 cases of AAS users. Of these, 168 cases had the hypogonadism clearly diagnosed and proven to be linked exclusively to AAS abuse. However, between these 168 cases, only 38 cases presented fully known outcomes and among these, merely in 4, the hypogonadism was completely reversible (2 based on drug therapy) with HPG axis recovery. In conclusion, this review presents evidences that AAS-induced hypogonadism is a seriously underestimated problem, and in the majority of cases, full recovery is very difficult to succeed.
We investigated the niche breadth and overlap of the fish species occurring in four environments affected by the Coaracy Nunes reservoir, in the Amapá Brazilian State. Seasonal samples of fishes were ...taken using a standard configuration of gillnets, as well as dragnets, lines, and cast-nets. Five hundred and forty stomach contents, representing 47 fish species were analyzed and quantified. Niche breadth and overlap were estimated using indexes of Levins and Pianka, respectively, while interspecific competition was evaluated using a null model (RA3). ANOVA and the Kruskal-Wallis test were used, respectively, to evaluate differences in niche breadth and overlap between areas. The data indicate that the majority of the fish species belong to the piscivore, omnivore, and detritivore guilds. These species have likely colonized the environments due to the availability of suitable feeding resources, and the favorable physical conditions created by the river damming. Overall, few species have ample niches, but most of them are highly specialized. Resources seasonal variation had little effect on the feeding behavior of most species in the study areas. The null models indicated that competition was not a factor determining on community structure.
Urbanization causes environmental impacts that threaten the health of aquatic communities and alter their recovery patterns. In this study, we evaluated the diversity of intertidal fish in six areas ...affected by urbanization (areas with native vegetation, deforested areas, and areas in process of restoration of vegetation) along an urban waterfront in the Amazon River. 20 species were identified, representing 17 genera, 14 families, and 8 orders. The different degrees of habitat degradation had a major effect on the composition of the fish fauna; the two least affected sectors were the only ones in that all 20 species were found. Eight species were recorded in the most degraded areas. The analysis revealed two well-defined groups, coinciding with the sectors in better ecological quality and degraded areas, respectively. The native vegetation has been identified as the crucial factor to the recovery and homeostasis of the studied ecosystem, justifying its legal protection and its use in the restoration and conservation of altered and threatened environments. These results reinforce the importance of maintaining the native vegetation as well as its restoration in order to benefit of the fish populations in intertidal zones impacted by alterations resulting from inadequate urbanization.
In order to provide guidelines for the management of fish stocks in artificial reservoirs in the Amazon region, the present study analyzed the composition and structure of the fish communities of ...four sectors (upstream, lake, reservoir, and downstream) of the area affected by the Coaracy Nunes hydroelectric reservoir on the Araguari River in the Brazilian state of Amapá. Variation in ecological parameters was analyzed in the context of the impacts suffered since the damming of the river approximately 40 years ago. Standardized samples of fish were collected in gillnets during eight campaigns in 2009 and 2010. Abundance and biomass were initially evaluated by Analysis of Variance (ANOVA), and lognormal, log-series, geometric series, and broken stick models were then calculated. The K-dominance and Abundance-Biomass (ABC) curves were also analyzed, together with the size-spectrum of the specimens. The results indicated that the sector downstream from the dam had the highest species richness, and was most consistent with the broken stick model. The ABC and K-dominance analyses also confirmed that this sector was the most balanced, in ecological terms. The lake sector had the only community that fitted the geometric series model, and all the analyses indicated a predominance of small individuals, typical of impacted communities. The analyses of the reservoir sector indicated a disturbed environment, whereas the upstream sector was characterized by a more balanced community, reflecting its greater resilience to the impacts caused by the reservoir, and its potential of this area for the conservation of local fish communities. The results also confirmed the applicability of the analytical tools employed for the study of fish communities in reservoir environments.
The objective of this study was to document the structure of the fish assemblages found in the aquatic environments affected by the Coaracy Nunes hydroelectric reservoir in Ferreira-Gomes, Amapá ...(Brazil) and the principal factors that determine this structure. In order to do this, standardized samples were collected of the fauna and the environmental parameters in the four principal sectors of the reservoir (upstream, the reservoir, the lake, and downstream). Fish species richness, abundance, and biomass were estimated for each sector. The abundance data were analyzed using null models of co-occurrence. A multivariate BIO-ENV analysis was used to examine the relationship between biological and environmental factors. The relationship between species richness and biomass of both prey and predator species was analyzed to determine whether predation was affecting community structure. Size spectrum analysis was conducted to verify whether fishing has influenced community structure. The results indicated contrasting seasonal patterns of deterministic processes in the downstream and lake sectors, suggesting that competition or abiotic factors may play a role in community structure. Stochastic patterns were recorded in the other sectors. Environmental factors, such as water transparency and depth, and the reservoir level were also closely related to the relative abundance of species in the communities. The relationship between the species richness and the biomass of predators and prey indicated that predation was an important determinant of community structure, which was interrupted by selective fishing. Despite the stochastic nature of most processes, deterministic factors were fundamental to the structure of the assemblages found in the downstream and lake sectors.
The oral cytotoxicity, antimicrobial and anti-demineralizing effects of a tincture from
Link tincture (BFLT) were evaluated
and
. Susceptibility tests (minimum inhibitory and microbicidal ...concentrations-MIC and time-kill assay-MMC) were performed against planktonic oral microorganisms. The contents of phenolic compounds were investigated. Cytotoxic potential was evaluated on oral fibroblasts after 1-5 min exposure to BFLT. Blocks of sound bovine enamel (
= 60) were inoculated with a saliva pool and sustained in a multiple plaque growth system for 48 h to form a biofilm. Biofilm blocks were randomly divided into groups-G (
= 10): G1-Baseline (48 h maturation biofilm), G2-BFLT 23.2 mg/mL, G3-Ethanol 81.20 g/mL, G4-Chlorhexidine 0.12%, G5-Growth control, and G6-Blank control. Treatments (50
L/1 min) were performed once a day for a week.
spp. (S) and total microorganism (TM) counts were expressed as Log
CFU/mL. Biofilm height was evaluated by confocal microscopy analyses (CMA). Final surface hardness was assessed and percentage of microhardness loss (% MHL) was calculated. Results were significant when
< .05. BFLT inhibited all tested microorganisms (MIC = 1.3-23.2 mg/mL) and promoted optical reduction (0.05-0.22 nm) of all microorganisms after 48-h treatment compared with controls. After 5-min treatment, BFLT showed low values of cell death (3.20%). G2-BFLT reduced S (6.61 ± 0.20) and TM (7.14 ± 0.38) compared with G1-Baseline (S = 7.82 ± 0.28; TM = 8.81 ± 0.67) and G5-Growth control (S = 7.48 ± 0.39; TM = 7.89 ± 0.68); but G4-chlororexidine (S = 6.11 ± 0.48; TM = 6.45 ± 0.16) showed the highest antibiofilm activity. CMA was not different among treatment groups. G2 showed lower % MHL compared with G5, although G4 presented the lowest. Results suggest BFLT is beneficial against dental caries, showing antimicrobial effects against a mature dental biofilm and no cytotoxicity.
The external morphology of the nymph of Amblyomma geayi Neumann is described by optical and scanning electron microscopy. Unfed nymphs were obtained from an engorged A. geayi female, which had been ...collected on a sloth (Bradypus variegatus) from Belém municipality, State of Pará, northern Brazil, and was kept under laboratory conditions. With the present description, we propose a modification of a taxonomic key published in 2010 for the Amblyomma nymphs that occur in Brazil, through the inclusion of A. geayi. The nymph of A. geayi is morphologically very similar to the nymph of Amblyomma parkeri Fonseca and Aragão, with only slight morphological differences related to scutal surface and punctuations (more shagreened and less punctuated in A. geayi). These 2 nymphs differ from all other known Amblyomma nymphs from Brazil by the combination of auriculae present as small posterolateral rounded projections, eyes located at the level of the scutal midlength, and a rounded hypostome. These nymphal similarities as well the morphology of the adult stage corroborate previous studies that showed that A. geayi and A. parkeri are genetically closely related. Unpublished host records of the nymphs of both A. geayi and A. parkeri are provided. Established populations of A. geayi and A. parkeri seem to be geographically separated, since all confirmed records of A. geayi are from the northern half of South America (mainly the Amazonian region) and Central America, whereas all known records of A. parkeri are from the Atlantic rainforest biome in northeastern, southeastern, and southern Brazil.
The inhibitory activity of a Bauhinia forficata tincture (TBF) was investigated against oral microorganism's strains and against a mature oral biofilm. The viability of planktonic cells was analyzed ...by Minimal Inhibitory and Microbicidal concentrations of TBF. Salivary samples from health volunteers were collected and mixed to form a saliva pool. An aliquot from this pool were seeded on membranes, which were incubated to form biofilm (48 h). The biofilm was treated according to the groups: G1-Chlorhexidine 0.12%; G2-TBF at the highest MMC; G3-Ethanol at the TBF highest MMC. G4 was the growth control. Streptococcus spp. (S) and total microorganisms (TM) from biofilm were counted. TBF was microbicidal against all oral pathogens. G2 was able to reduce the counts of S and TM from biofilm compared to G3 and G4, but less than G1 (p < 0.05). TBF is able to reduce the microbial levels from a mature oral biofilm.
PDF
