Efeitos da tilápia do Nilo (Oreochromis niloticus) e do enriquecimento por nutrientes sobre a comunidade planctônica em um lago artificial no semi-árido brasileiro

The major aim of this study was to test the hypothesis that the introduction of the Nile tilapia (Oreochromis niloticus) and the enrichment with nutrients (N and P) interact synergistically to change the structure of plankton communities, increase phytoplankton biomass and decrease water transparency of a semi-arid tropical reservoir. One field experiment was performed during five weeks in twenty enclosures (8m3) to where four treatments were randomly allocated: with tilapia addition (T), with nutrients addition (NP), with tilapia and nutrients addition (T+NP) and a control treatment with no tilapia or nutrients addition (C). A two-way repeated measures ANOVA was done to test for time (t), tilapia (T) and nutrient (NP) effects and their interaction on water transparency, total phosphorus, total nitrogen, phytoplankton and zooplankton. The results show that there was no effect of nutrient addition on these variables but significant fish effects on the biomass of total zooplankton, nauplii, rotifers, cladocerans and calanoid copepods, on the biovolume of Bacillariophyta, Zygnemaphyceae and large algae (GALD ≥ 50 μm) and on Secchi depth. In addition, we found significant interaction effects between tilapia and nutrients on Secchi depth and rotifers. Overall, tilapia decreased the biomass of most zooplankton taxa and large algae (diatoms) and decreased the water transparency while nutrient enrichment increased the biomass of zooplankton (rotifers) but only in the absence of tilapia. In conclusion, the influence of fish on the reservoir plankton community and water transparency was greater than that of nutrient loading. This finding suggests that biomanipulation should be a greater priority in the restoration of eutrophic reservoirs in tropical semi-arid regions

Trabalho e família: um estudo da interação de papéis com secretários executivos

The balance between the demands of two important spheres of human life, work and family, has become a challenge due to the pressures of the contemporary that is expanding around the difficulties of reconciling these two comínios. In this sense, this research aimed to understand the work-family interaction in the perception of executive secretaries. The analysis approach used was qualitative research, by worrying about a reality that can not be quantified due to the subjectivity of his goal. The data collection technique used was the semistructured interview to twenty executive secretaries, servants of a Federal Institution of Higher Education. For the understanding and interpretation of the data, we used the technique of content analysis. The results of both analyzes identified the existence of conflict as enrichment in this interaction. The time was identified as the largest generator of conflict work. The overload, relationship stress and conflict emerged as elements common to both domains. As main implications of labor disputes, were revealed: problamas health for secretaries and stress. As main implications of family conflicts emerged: motivation for work, lower performance and lack of concentration. The attempt at balance was identified as the strategy most used by secretaries to minimize work-family conflict. The work-family enrichment was seen as resources that contribute to improving the lives of the secretary in both domains. The opportunity to add knowledge was highlighted as enriching element of work and family values ​​as elements enriching family. The support and experience emerged as enrichment items common to both domains. Regarding the implications of enrichment resulting from the interaction of work and family, the more perceived by respondents were: increased knowledge and skills, material and psychological benefits, improved quality of life and personal and professional fulfillment. From the perception of executive secretaries, work and family spheres of human life are essential and complementary, and that help is contrary, however, this relationship is the primary management of conflicts, ie, how the individual sees and manages the negative side of the work-family

Geografia da dominação: um estudo sobre a organização espacial da terra do sal (Macau-RN)

This work aims to understand the spatial organization in the Town of Macau, State of Rio Grande do Norte, Brazil. This approach focus on bringing back the history of the town, the main personages responsible for the construction of this place, denominated "social agents", as well as its social processes and the spatial forms derived from them. As the personages and their practices were identified, it was found out the existence of a driving force for structuring, interlocking, and maintaining the actions carried out by the social agents during the time. Such actions were materialized in the urban space: "the social segregation". The social segregation takes place as a specific geography of domination. The outcome of those owning the best areas" and ways of accessibility in the urban space, varies from the enrichment by property valorization, because of the concentration of public investments of infrastructure, to the comfort of easily reaching all the daily needs related to the displacements in the urban space. In the latter case, such facility has contributed to improve life quality. While one takes advantage of the location in the urban space, others are negatively affected by the same process. This research identified the salina worker as the weakest element of this social structure, occupying the urban periphery of the town of Macau. Such area is characterized by the lack of services and urban equipment in opposition to the center of the town, the locus of elite. This way, it is established the most known segregation pattern: center x periphery, in which the space acts as a mechanism of segregation

Eutrofização e capacidade de carga de fósforo de seis reservatórios a bacia do Rio Seridó, região semi-árida do Estado do RN

The eutrofization is a natural process of accumulation of nutrients in aquatic´s body that it has been accelerated for the human´s actives, mainly the related with the activities of camp, industrial and the inadequate disposition of the domestic sewage. The enrichment of the aquatic´s body with nutrients, mainly the nitrogen and the phosphorus, and the consequent proliferation of algae and Cyanobacteria can commit the quality of the water for the public provisioning, for the fish farming and for other ends. The problem becomes more critical when there is a shortage of water naturally as in the semi-arid area of the Brazilian northeast. Before that problem this work had as objective evaluates the trophic state of six reservoirs of the basin of River Seridó of Rio Grande of Norte and also estimate the capacity of load of match of the reservoir and risk probabilities based on the established limits by the resolution Conama 357/05. The results demonstrate that the six reservoirs are eutrofization, with concentration of total phosphorus and cloro a in the water upster to 50 e 12 μg l-1. The results show that space homogeneity exists in the state trophic of the reservoirs, but a significant variation interanual in function of the increase of the concentrations of nutrients and decrease of the transparency of the water with the reduction of the body of water accumulated in the reservoirs.The results of the simulation risk estocastic show that the reservoirs could receive annually from 72 to 216 Kg of P, assuming a risk of 10% of increasing in more than 30 μg l-1 the annual medium concentrations of total match in the water of these reservoirs. This load could be high in until 360 kg of P a year in case the managers assume a risk of 10% of increasing in more than 50 μg l-1 the annual medium concentrations of total phosphorus in the waters of these reservoirs