Esse Herrera, Carlos

Microplastics (MPs) have been recognized as one of the most ubiquitous environmental pollutants globally. They have been found in all ecosystems studied to date, threatening biological diversity, ecosystem functioning and human health. The present study aimed to elucidate the environmental and anthropogenic drivers of MP dynamics in the whole catchment of the Biobío river, one of the largest rivers in South America. MP concentration and characteristics were analysed in 18 sites subjected to different sources of pollution and other human-related impacts. The sampling sites were classified in relation to altitudinal zones (highland, midland and lowland) and ecosystem types (fluvial and reservoir), and different water and territorial environmental variables were further collated and considered for analysis. Seven types of microplastic polymers were identified in the samples analysed, with a catchment mean (±SE) MP concentration of 22 ± 0.4 particles m−3, and MP presence being significantly higher in lowlands (26 ± 2 particle m−3) and in reservoirs (42 ± 14 particle m−3). The most abundant type of MP was fragments (84%), with a mean concentration of 37 ± 6 particles m−3. Overall, MP concentrations were low compared to those found in other studies, with a strong influence of human population size.

The tiger crab Aegla concepcionensis Schmitt, 1942 (Decapoda, Aeglidae) is a threatened freshwater decapod, endemic of Chile, with significant gaps in knowledge about its biology and ecology. The aim of this work was to contribute to the knowledge of the ecology of A. concepcionensis, through the extension of its known distribution range, recorded in a new type of ecosystem, and the description of the physicochemistry, vegetation and benthic macroinvertebrate and microalgal communities of those sites, which provides information about habitat use of the species. Our results show the presence of A. concepcionensis until 270 km south of the previously described range and reveal that the species inhabits streams and lakes. A. concepcionensis is associated to environments with cold and temperate waters, well oxygenated, with neutral pH and low conductivity, and characterized by low anthropic intervention, which is reflected in the high proportion of native riverine plant species and the high diversity of macroinvertebrate and microalgal benthic communities. We conclude that the previously restricted known distribution range of this species was mainly due to low sampling effort or misidentifications. Our results indicate that anthropic intervention should be avoided or minimized in the distribution area of A. concepcionensis, especially in those areas associated with urban expansion and touristic activities in streams and lakes.