Treated and highly diluted, but wastewater still impacts diversity and energy fluxes of freshwater food webs.

Wastewater treatment plants (WWTPs) have greatly improved water quality globally. However, treated effluents still contain a complex cocktail of pollutants whose environmental effects might go unnoticed, masked by additional stressors in the receiving waters or by spatiotemporal variability. We conducted a BACI (Before-After/Control-Impact) ecosystem manipulation experiment, where we diverted part of the effluent of a large tertiary WWTP into a small, unpolluted stream to assess the effects of a well-treated and highly diluted effluent on riverine diversity and food web dynamics. We sampled basal food resources, benthic invertebrates and fish to search for changes on the structure and energy transfer of the food web with the effluent. Although effluent toxicity was low, it reduced diversity, increased primary production and herbivory, and reduced energy fluxes associated to terrestrial inputs. Altogether, the effluent decreased total energy fluxes in stream food webs, showing that treated wastewater can lead to important ecosystem-level changes, affecting the structure and functioning of stream communities even at high dilution rates. The present study shows that current procedures to treat wastewater can still affect freshwater ecosystems and highlights the need for further efforts to treat polluted waters to conserve aquatic food webs.

The joint influence of the variables educational level and gender on children's drawings of the plant world.

Drawing is a form of creative expression that children enjoy from a young age. Drawing is also an effective and engaging strategy for exploring children's comprehension of the natural world. Examination of the content, colours, and developmental changes of children's drawings can provide us with valuable insights into how understanding of plant life develops during childhood. In this regard, previous studies have analysed the relationship that the representations that children draw when graphically expressing their understanding of the plant world have with the variables gender and educational level. This line of research has established that children's drawings of the plant world vary significantly when those drawn by older children are compared with those drawn by younger students and that the differences between girls and boys seem irrelevant. However, no studies have investigated the combined influence that both variables (gender and educational level) have on children's representation of the plant world. This study investigated this influence by examining 251 drawings by young children (aged 4-7 years). The results indicated that gender and educational level influenced key pictorial elements. Thus, that when comparing the understanding of biological phenomena through drawings between girls and boys, it is important to control for educational level.

Collagen in the media: An analysis of news published between 2016 and 2018.

This study examines 102 news items related to collagen as a dietary supplement, written in Spanish and published over a period of 2 years, in both digital and print media. The objective of this study is to evaluate the scientific rigor and consistency of the news information included in the sample. Errors and incorrect uses relative to the current scientific knowledge were identified in the analyzed information, and these errors were classified according to the criteria extracted from previous research. The evidence gathered shows a relevant frequency of errors in the information examined. The results are discussed in light of the role that the media plays in the transmission of beliefs regarding the value of collagen supplements.

Quantifying and addressing the prevalence and bias of study designs in the environmental and social sciences.

Building trust in science and evidence-based decision-making depends heavily on the credibility of studies and their findings. Researchers employ many different study designs that vary in their risk of bias to evaluate the true effect of interventions or impacts. Here, we empirically quantify, on a large scale, the prevalence of different study designs and the magnitude of bias in their estimates. Randomised designs and controlled observational designs with pre-intervention sampling were used by just 23% of intervention studies in biodiversity conservation, and 36% of intervention studies in social science. We demonstrate, through pairwise within-study comparisons across 49 environmental datasets, that these types of designs usually give less biased estimates than simpler observational designs. We propose a model-based approach to combine study estimates that may suffer from different levels of study design bias, discuss the implications for evidence synthesis, and how to facilitate the use of more credible study designs.