Efeitos de florações de cianobactérias sobre os cladóceros ceriodaphnia dubia e daphnia gessneri

Cyanobacterial blooms are common in eutrophic reservoirs in Brazilian northeastern semi-arid. Given this reality, the present study aimed to analyze the effect of potentially toxic cyanobacterial blooms in Gargalheiras reservoir (semi-arid) on the cladocerans Ceriodaphnia dubia and Daphnia gessneri. In vitro chronic bioassays were performed with reservoir water dilutions from August/2011 to May/2012 and the following effects were evaluated on: intrinsic rate of population growth (r), reproductive parameters (age of first reproduction and fecundity per capita) and cladocerans movements. Phytoplankton was dominated by Cylindrospermopsis raciborskii and Planktothrix agardhii and saxitoxin and microcystin were detected in reservoir water. In most months C. dubia showed differences in r between control (absence of cyanobacteria) and treatments, and has shown negative effects on reproductive parameters. In all months paralysis of swimming movements was observed in C. dubia when both C. raciborskii and saxitoxin (cyanotoxin neurotoxic) were present in water. While C. dubia was sensitive to the reservoir water containing cyanobacteria, D. gessneri showed less intense negative effects in r and reproductive parameters. Furthermore, D. gessneri showed no paralysis of swimming movements. These results support the hypothesis in the literature that D. gessneri is resistant to the Cylindrospermopsis effects. The clone‟s life history may be a key to understand the results. The C. dubia clone, isolated from eutrophicated environment, is in the lab for ten years and it is an exotic species in Brazil. D. gessneri is a common species in the country and this clone was isolated from the Gargalheiras reservoir (where there are constant blooms of potentially toxic cyanobacteria) a year ago. Perhaps the recent contact with cyanobacteria explain the higher resistance presented by this D. gessneri clone. In conclusion, the cladocerans studied have different levels of sensitivity to cyanobacteria, characterizing species-specific responses

Revitalização do Rio Golandim (RN/Brasil) após décadas de contaminação por efluentes industriais e domésticos: este rio está recuperado?

Environmental pollution causes the loss of the quality of aquatic resources and also affects the health of human beings. The Golandim River is located in São Gonçalo do Amarante (RN Brazil) and had its water recovered seven years ago by measurements of parameters of the water s quality analyses physicochemistry, microbiological and heavy metals. However, it is not well established if this river is truly recovered, so this study provides a wide knowledge about the quality of these waters. Therefore, this investigation was accomplished by assays of ecotoxicology utilizing Ceriodaphnia dubia and of genotoxicity of the river s water using a biomarker Tradescantia Pallida (Trad-MCN). In set, it carried through a study of environmental perception through questionnaires that approached questions related to the profile of the interviewed one, knowledge on the environment and of the river Golandim with the community that lives in the neighborhoods of the river to diagnosis as they perceive the environment where live and its problems. The assays of the water had been carried out by collecting samples in three different sites of the Golandim River. They were collected between the periods of December 2010 (dry season in the northeast of Brazil) and July 2011 (rainy season in the northeast of). The analysis of the data allowed observing that the majority of the inhabitants are adult and presents a global vision of what it is part of the environment, the majority mentions the pollution of the river as one of the problems of the city, considering it serious. The ecotoxicology assay showed that there was not acute toxicity in all three samples collected. Meanwhile, all these three samples demonstrated significant chronic toxicity. The results from the Trad-MCN assay presented an increase in the frequency of micronucleus in one of the sites analyzed (S3) (p<0.01), in both seasons collected. On the other hand, the sites S1 and S2 did not presented a significant increase of micronucleus using this bioassay. The analyses of chemicals detected an increase in the levels of some metals, in different seasons and samples, which can be associates with some compounds found in urban and industrial areas. On the other hand, the physicochemistries parameters demonstrated that the Golandim River is recouped, when compared with the values presented at the CONAMA s legislation. However, these results indicate the presence of compounds capable of inducing chromosomal mutation in plants. On the other hand, the parameters physicistchemistries demonstrate that the river Golandim is if recouping, since when compares the values observed with the legislation of the CONAMA. All these results point to the fact that the Trad-MCN assay was sensitive and efficient biomarker for chromosomal instability and the C. dubia ecotoxicology assay was as though an efficient biomarker of toxicity of water s quality. The results from Trad-MCN associated with the ecotoxicology demonstrates that these analyses are important for environmental monitoring, once the first bioassay described above indicates alterations at the standards of cells and the other one indicates alterations at the standards of organisms. This study alerts for the necessity to carry out biological assays for the analyses of the water s quality

A comunidade zooplanctônica como bioindicadora do estado trófico de reservatórios da região semiárida tropical

E utrophication in continental aquatic ecosystems and the following deterioration of water quality are some of the greatest problems to be solved in this century. Due to their own peculiarities reservoirs from semi - arid regions constitute a great challenge to water management because of their greater vulnerability to eutrophication process. I dentification of biolo gical community components that may be used as bioindicators is important to allow an early detection of adverse changes, and also to provide subsidies for management and conservation actions. The aim of the present study is to evaluate the potential of zo oplankton community as bioindicator of the trophic state of two reservoirs belonging to the Piranhas - Açu basin, RN, Brazil: Boqueirão de Parelhas and Passagem das Traíras. Monthly sampling s of both systems were carried out in both systems during the period of January to December. Measurements were performed for temperature, pH, dissolved oxygen and water electrical conductivity besides water samples collection for nutrients, suspended solids, chlorophyll - a and zooplankton analyses. T axonomic composition of zooplankton , density and biomass were analysed. Trophic state index, ABC curves , W statistic and the Calanoida: Cyclopoida ratio were also obtained. The results evidenced that Boqueirão de Parelhas reservoir was a mesotrophic sy stem, and Passagem das Traíras r eservoir was eutrophic. In both reservoirs zooplankton community had low species richness, mostly constituted by tolerant species which have wide geographical distribution, as well the dominance of the rotifers Brachionus havanaensis , B. calyciflo rus and Keratella tropica ; of the calanoid copepods Notodiaptomus cearensis and N. iheringi ; cyclopoid copepod Thermocyclops decipiens, and of the cladocerans Ceriodaphnia cornuta and Diaphanosoma spinulosum . Among the biological indices the ABC curves fo r the zooplankton community indicated a moderate dis turbance in both reservoirs, th e Calanoida: Cyclopoida ration indicated not impacted environments , e xcept during the end of the study to the reservoir Passagem das Traíras . It was concluded that the indices used are good indicators of disturbance and alteration in the community, however they are not good indicators for monitoring the trophic state of the studied reservoirs due to the simultaneous occurrence of other factors selecting species, as the c oncentration of ions and high turbidity, which are part of the reservoir characteristics of semiarid.