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