Federal University of São Carlos

About: Federal University of São Carlos is a education organization based out in São Carlos, Brazil. It is known for research contribution in the topics: Population & Microstructure. The organization has 16471 authors who have published 34057 publications receiving 456654 citations. The organization is also known as: UFSCar & Federal University of São Carlos.

Food partitioning among some characids of a small Brazilian floodplain lake from the Paraná River basin

Abstract: Resource partitioning and the seasonal patterns of food intake of four characids (Astyanax fasciatus, A. bimaculatus, A. schubarti and Cheirodon stenodon) were studied during 1988 in a floodplain lake of Mogi-Guacu River, Sao Paulo State. For interspecific comparisons, data of the previously studied Moenkhausia intermedia have also been used. A. fasciatus and A. bimaculatus can be considered omnivorous species, while A. schubarti and C. stenodon are predominantly herbivorous. The river flood cycle (following the wet season October-March and dry season April-September) seems to influence both seasonal food intake and food overlap between species. February-March and September-October are probably the months of highest food availability, and the months preceding these periods have the lowest resource amount. Our study shows that both omnivorous and herbivorous species modified the intensity of their interactions according to this cycle. Omnivorous species maintained fairly segregated diets when resources were presumably limited, and showed a rapid change from distinct food niches in the dry season to widely overlapping ones when resources were presumably more abundant. Conversely, the herbivorous species showed higher overlap during the dry season. Acute cyclic changes in the environment, as observed in this study, suggest the necessity of small interval sampling in food partitioning studies in tropical freshwater floodplains, in order to understand how species interact and cope with changes in food availability.

Diversidades filogenética e funcional: novas abordagens para a Ecologia de comunidades

Abstract: Embora a diversidade pareca ser o conceito ecologico mais intuitivo, nenhuma definicao consensual foi formulada. As medidas tradicionais de diversidade, que levam em conta apenas o numero de especies e suas contribuicoes relativas, tem se mostrado estimativas pouco preditivas da estrutura e do funcionamento das comunidades. Medidas de diversidade que incorporem informacoes sobre as relacoes filogeneticas das especies ou suas caracteristicas funcionais podem ser melhores do que as medidas tradicionais para muitas finalidades. Apresentamos uma pequena revisao das propriedades e aplicacoes de algumas medidas de diversidade. Enfatizamos aqui duas abordagens recentes e promissoras, as diversidades filogenetica e funcional, que tem se mostrado mais sensiveis para detectar respostas das comunidades as mudancas ambientais. Na diversidade filogenetica, as relacoes de parentesco entre as especies sao levadas em conta, enquanto que na diversidade funcional tracos que devem ter relacoes com o funcionamento das comunidades sao considerados. Discutimos ainda os desafios e as perspectivas para o uso dessas duas abordagens na ecologia.

Effects of Different Microplastics on Nematodes in the Soil Environment: Tracking the Extractable Additives Using an Ecotoxicological Approach

Abstract: With increasing interest in the effects of microplastics on the soil environment, there is a need to thoroughly evaluate the potential adverse effects of these particles as a function of their characteristics (size, shape, and composition). In addition, extractable chemical additives from microplastics have been identified as an important toxicity pathway in the aquatic environment. However, currently, little is known about the effects of such additives on the soil environment. In this study on nematodes (Caenorhabditis elegans), we adopted an ecotoxicological approach to assess the potential effects of 13 different microplastics (0.001-1% of soil dry weight) with different characteristics and extractable additives. We found that poly(ethylene terephthalate) (PET) fragments and polyacrylicnitrile (PAN) fibers show the highest toxicity, while high-density polyethylene (HDPE), polypropylene (PP), and polystyrene (PS) fragments induced relatively less adverse effects on nematodes. In addition, low-density polyethylene (LDPE) induced no toxicity within our test concentration range for the acute period. Acute toxicity was mainly attributed to the extractable additives: when the additives were extracted, the toxic effects of each microplastic disappeared in the acute soil toxicity test. The harmful effects of the LDPE films and PAN fibers increased when the microplastics were maintained in the soil for a long-term period with frequent wet-dry cycles. We here provide clear evidence that microplastic toxicity in the soil is highly related to extractable additives. Our results suggest that future experiments consider extractable additives as key explanatory variables.