Association between biotic and abiotic parameters and the occurrence of cyanobacteria in a Brazilian reservoir

The water reservoir of Vargem das Flores, Brazil, has been subject to eutrophication problems. The occurrence of cyanobacterial blooms in this water body has raised concerns regarding the presence of toxic metabolites. In order to understand the factors that promote the proliferation and distribution of cyanobacteria in the reservoir, physicochemical parameters, species composition, and toxicity of the reservoir water column were analyzed at monthly intervals over a 3-year period (2004-2007) using a range of analytical techniques. The results showed that cyanobacteria were absent in the dry period, returning after the onset of stratification. A succession pattern was observed within this group. The Aphanocapsa genus was dominant in the last rainy period of the study (October 2006 to March 2007). However toxicity was only detected when the genera Microcystis and Sphaerocavum were present (October 2005). The principal components analysis showed negative correlation between cyanobacteria and orthophosphate. The change of dominant cyanobacteria along the 3 years of study and the final prevalence of nontoxic genera in the reservoir is an evidence of water quality improvement in response to the management techniques implemented in the reservoir basin.     

Chironomidae and Oligochaeta for water quality evaluation in an urban river in southeastern Brazil

Considering the importance of benthic macroinvertebrates for diagnosis of variations in the ecological conditions of aquatic habitats, the aim of this study was to investigate the structure of the Chironomidae and Oligochaeta assemblages along an organic pollution gradient. The fauna specimens were obtained with the use of artificial substrates, and the environmental variables were recorded at five sites of the São Lourenço River, during 12 months. Metrics of the assemblage and detrended correspondence analysis were used to verify the response of the fauna to the pollution gradient. Procrustes analysis was used to verify whether the data on the Chironomidae and Oligochaeta assemblages, as well as the taxonomic and numerical resolution of these groups, provide similar results in relation to the pollution gradient. The richness, evenness, and taxonomic composition of the Chironomidae and Oligochaeta assemblages varied significantly among the collection sites, with distinct conservation conditions. Genera of the subfamilies Orthocladiinae and Tanypodinae were associated with the sites upstream of the urban area, where the dissolved oxygen levels are higher. Species of Oligochaeta and the genus Chironomus were associated with more organically polluted sites. No concordance was observed in the response of the Chironomidae and Oligochaeta assemblages in relation to the environmental variables, indicating the need to use both groups in biomonitoring studies. On the other hand, both the data on composition (presence or absence) and those on the lowest taxonomic resolution (abundance of subfamilies) were effective to diagnose the pollution gradient in the river studied. Therefore, when the environmental conditions along a river’s gradient are contrasting, we suggest the use of the lowest taxonomic resolution of Chironomidae and Oligochaeta in biomonitoring. That procedure considerably reduces the assessment time, besides being a method that can be used by people not specializing in the taxonomy of groups.     

A review on human attitudes towards reptiles in Brazil

For many millennia humans and reptiles have interacted, but the attitude of humans towards these animals has depended on culture, environment, and personal experience. At least 719 reptile species are known to occur in Brazil and about 11% of this fauna has been exploited for many different purposes, including bushmeat, leather, ornamental and magic/religious uses, and as folk medicines. Brazil can therefore serve as an interesting case study for better understanding reptile use by human societies, and the present paper catalogues some of the reptile species being used in Brazil and discusses implications for their conservation. A literature review indicated that 81 reptile species are culturally important in this country, with 47 (58%) species having multiple uses, 54 being used for medicinal purposes, 38 as food, 28 for ornamental or decorative purposes, 20 used in magic/religious practices, 18 as pets, and 40 are commonly killed when they come into contact with humans. Regarding their conservation status, 30 (37.5%) are included on State's Red List, Brazilian Red List or the IUCN Red List. There are many forms of interaction between reptiles and humans in Brazil-although most of them are quite negative in terms of wildlife conservation-which reinforces the importance of understanding such uses and interactions in the context of protecting reptiles in Brazil. A better understanding of the cultural, social, and traditional roles of these reptiles is fundamental to establishing management plans for their sustainable use.     

Cytotoxicity and genotoxicity of Guaribas river water (Piauí, Brazil), influenced by anthropogenic action

In general, tropical rivers have a great impact on human activities. Bioaccumulation of toxins is a worldwide problem nowadays and has been, historically, overlooked by the supervisory authorities. This study evaluated cytogenotoxic effects of Guaribas river (a Brazilian river) water during dry and rainy seasons of 2014 by using the Allium cepa test system. The toxicogenetic variables, including root growth, mitotic index, and chromosomal aberrations, were analyzed in meristematic cells of A. cepa exposed to water samples taken from the up-, within, and downstream of the city Picos (state: Piauí). The physical-chemical parameters were also analyzed to explain water quality and possible anthropogenic action. Additionally, the presence of heavy metals was also analyzed to explain water quality and possible damaging effects on eukaryotic cells. The results suggest that the river water exerted cytotoxic, mutagenic, and genotoxic effects, regardless of the seasons. In addition, Guaribas river presented physico-chemical values outside the Brazilian laws, which can be a characteristic of human pollution (domestic sewage, industrial, and local agriculture). The genetic damage was positively correlated with higher levels of heavy metals. The pollution of the Guaribas river water may link to the chemical contamination, including the action of heavy metals and their impacts on genetic instability in the aquatic ecosystem. In conclusion, necessary steps should be taken into account for further toxicogenetic studies of the Guaribas river water, as it has an influence in human health of the same region of Brazil.     

The efficiency of tobacco Bel-W3 and native species for ozone biomonitoring in subtropical climate, as revealed by histo-cytochemical techniques

We aimed to verify whether hydrogen peroxide (H₂O₂) accumulation and cell death are detected early in three bioindicators of ozone (O₃), Nicotiana tabacum ‘Bel-W3’, Ipomoea nil ‘Scarlet O’Hara’ and Psidium guajava ‘Paluma’, and whether environmental factors also affect those microscopic markers. The three species were exposed to chronic levels of O₃ in a subtropical area and a histo-cytochemical technique that combines 3,3′-diaminobenzidine (DAB) with Evans blue staining was used in the assessments. The three species accumulated H₂O₂, but a positive correlation with O₃ concentration was only observed in N. tabacum. A positive correlation between O₃ and cellular death was also observed in N. tabacum. In I. nil and P. guajava, environmental factors were responsible for symptoms at the microscopic level, especially in P. guajava. We conclude that the most appropriate and least appropriate bioindicator plant for O₃ monitoring in the subtropics are N. tabacum ‘Bel-W3’ and P. guajava ‘Paluma’, respectively.     

Esterase inhibition in tadpoles of <Emphasis Type="Italic">Scinax fuscovarius</Emphasis> (Anura,Hylidae) as a biomarker for exposure to organophosphate pesticides

Purpose  

Organophosphate pesticides (OPs) are among the most used insecticides in agriculture, causing the inhibition of esterases like acetylcholinesterase (AChE), butyrylcholinesterase (BChE) and carboxylesterase (CbE). Pesticides can reach the aquatic environment, posing risks to non-target organisms, including tadpoles.     

A knowledge network to promote the use and valorization of wild food plants in the Pantanal and Cerrado,Brazil

Regional Environmental Change - The conservation and use of wild food plants should include local people in the decision-making process, and many countries have done so. However, interacting with...