Frequently new pollutants are released into the environment, demanding the employment of generic methods to detect toxic responses. In vitro bioassays such as the yeast estrogenicity screening (YES) allow detecting estrogenic and citotoxic compounds avoiding the employment of invasive methods. We determined the cytotoxicity and estrogenic activity in sediments of the Santa Lucia River Basin (Uruguay) using YES assay and the association with land uses and parameters of water quality and sediment. Water quality parameters confirm the eutrophication process of the Santa Lucía River, which was mainly reflected by high levels of TP and ammonium. High values of estrogenic activity in sediments (E2-EQ 8.49 ng g -1 of sediment) were found mainly in urbanized and cultivated areas. However, estrogenicity and cytotoxicity also was found in sites associated with other land uses such as rangelands. These data provide evidence that Santa Lucía River basin contains a variety of chemicals (including estrogenic and toxic chemicals of unknown and potentially diverse sources) that should be investigated further. YES assay proved to be a useful tool for characterizing estrogenic responses, and due to the human and ecological health importance, we suggest the employment of these kinds of bioassays as tools for environmental monitoring of EDCs substances.

Abstract:The study of geographic variation of individual traits is an important component of evolutionary research, in that individual morphological features can be subjected to multiple selective pressures. The present work is aimed to analyze the geographic and seasonal variation in several digestive traits in Iheringichthys labrosus along three localities in the lower Río Uruguay. Statistically significant differences among locations and between seasons were found for all the variables assessed, the most noticeable of differences being observed were intestinal length, intestine weight, and liver weight. In part, these differences could be an adaptive response to changes in food availability and/or in the energetic costs of reproduction. Results obtained herein also suggest that individuals of this species spend enough time in each locality as to show a consistent response to local conditions in their digestive traits morphology.

Urbanization is regarded a major global threat to biodiversity and ecosystem functioning. Streams are among the most severely affected ecosystems due to worldwide urbanization. An increase in urbanization causes water quality deterioration and loss of habitat heterogeneity in streams. However, it is unclear how water quality deterioration and loss of habitat heterogeneity due to urbanization affect multitrophic diversity and performance of ecosystem functioning. We conducted 2,400 samplings in six streams across Uruguay to investigate how increases in urbanization (area and percentage of urbanization) affect the richness of three trophic groups of fishes and the standing stock biomass of the streams. We investigated the direct and indirect effects, mediated by water quality deterioration and habitat heterogeneity of the urbanization on carnivore, omnivore, and detritivore fish richness and standing stock biomass of streams. The increase in urbanization (area and percentagem) in the streams significantly decreased the richness of carnivores, omnivores, and detritivores fishes. The increase in urbanization also strongly decreased habitat heterogeneity and increased water quality deterioration, which indirectly decreased the carnivore, omnivore, and detritivore fish richness. Urbanization also had strong negative effects on the standing stock biomass of the streams. Our study illustrates that urbanization promotes water quality deterioration and loss of habitat heterogeneity in streams, which indirectly causes loss of multitrophic fish richness and biomass production of streams.

Human land‐use change is a major threat to natural ecosystems worldwide. Nonetheless, the effects of human land‐uses on the structure of plant and animal assemblages and their functional characteristics need to be better understood. Furthermore, the pathways by which human land uses affect ecosystem functions, such as biomass production, still need to be clarified. We compiled a unique dataset of fish, arthropod and macrophyte assemblages from 61 stream ecosystems in two Neotropical biomes: Amazonian rainforest and Uruguayan grasslands. We then tested how the cover of agriculture, pasture, urbanization and afforestation affected the taxonomic richness and functional diversity of those three species assemblages, and the consequences of these effects for animal biomass production. Single trait categories and functional diversity were evaluated, combining recruitment and life‐history, resource and habitat‐use, and body size. The effects of intensive human land‐uses on taxonomic and functional diversities were as strong as other drivers known to affect biodiversity, such as local climate and environmental factors. In both biomes, the taxonomic richness and functional diversity of animal and macrophyte assemblages decreased with increasing cover of agriculture, pasture, and urbanization. Human land‐uses were associated with functional homogenization of both animal and macrophyte assemblages. Human land‐uses reduced animal biomass through direct and indirect pathways mediated by declines in taxonomic and functional diversities. Our findings indicate that converting natural ecosystems to supply human demands results in species loss and trait homogenization across multiple biotic assemblages, ultimately reducing animal biomass production in streams.

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