Caffeine as a contaminant of periphyton: ecological changes and impacts on primary producers.

Every day, tons of caffeine is consumed by humans in beverages, medications or supplements, and a significant amount of this stimulant is released in domestic sewage. Once in aquatic environments caffeine interacts directly with the periphytic community, which is responsible for a significant part of primary production in aquatic ecosystems. However, the effects of exposure to caffeine are mostly unknown for both the periphyton and their predators. Aiming to comprehend the interaction between caffeine and the periphytic community, ecotoxicological experiments were performed by exposing a periphytic biofilm cultivated in the laboratory to different concentrations of caffeine, following concentrations found in domestic sewers. The impact of exposure to this contaminant was observed on the structure of the community through taxonomic evaluation, as well a set of physiological variables linked to primary production. After exposure to the highest caffeine concentration (300 µg L-1), the density of the genus Scenedesmus was severely affected, leading to an increase in cyanobacteria and diatoms. Both richness and diversity decreased after exposure, and there was lower photosynthetic activity, with light saturation point changing from 186 µmol m-2 s-1 in the control treatment to 108 µmol m-2 s-1 after exposure. Caffeine accumulation within the biofilm was also observed during the first 24 h, in the concentration of 0.14 µg /cm².

The association of social skills and behaviour problems with bullying engagement in Portuguese adolescents: From aggression to victimization behaviors.

This study examines sex differences regarding social skills, behavior problems and bullying engagement, and the association of social skills and behavior problems with bullying engagement, in adolescents. Participants were 447 Portuguese adolescents (252 girls and 195 boys) aged between 12 and 19-years-old. Social skills and behavior problems were assessed using the self-report version of Social Skills Improvement System - Rating Scales. Bullying engagement was assessed using the Scale of Interpersonal Behavior at School. Girls scored higher on social skills and reported more internalizing and fewer externalizing problems than boys, whereas boys reported more aggressive verbal behaviors than girls. Adolescents exhibiting fewer social skills and more internalizing and externalizing problems engage more frequently in bullying aggressive behaviors. In addition, adolescents presenting more internalizing and externalizing problems are more often victimized by bullies. Furthermore, boys more frequently engage in bullying aggressive and victimization behaviors, whereas younger adolescents with more social skills tend to engage less frequently in bullying aggressive behaviors.

The Association between Externalizing and Internalizing Problems with Bullying Engagement in Adolescents: The Mediating Role of Social Skills.

Bullying has severe public health consequences, due to its high prevalence worldwide and devastating effects on physical and mental health. Therefore, it is relevant to further understand the factors that contribute to the emergence and maintenance of bullying. This study aimed to examine the differential mediating role of social skills in the relationship between (i) externalizing problems and engagement in aggressive bullying behaviors, and (ii) internalizing problems and the engagement in victimization bullying behaviors. Participants were 669 Portuguese adolescents aged between 12 and 19 years. The Social Skills Improvement System-Rating Scales and the Scale of Interpersonal Behavior at School were used to assess social skills and the engagement in bullying behaviors, respectively. Boys scored higher on aggressive behaviors and externalizing problems. Girls reported higher scores on internalizing problems, communication, cooperation and empathy. Social skills differently mediated the association between behavior problems and engagement in bullying. While empathy negatively mediated the association between externalizing problems and aggressive bullying behaviors, assertiveness negatively mediated the relationship between internalizing problems and victimization bullying behaviors. The risk factors for engaging in bullying are discussed, and so are the protective ones, which may help to prevent bullying behaviors and reduce their negative impact.