Thaisa S. Michelan
Universidade Estadual de Maringá
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Publication
Featured researches published by Thaisa S. Michelan.
PLOS ONE | 2013
Thaisa S. Michelan; Sidinei Magela Thomaz; Luis Mauricio Bini
The role of the native species richness and density in ecosystem invasibility is a matter of concern for both ecologists and managers. We tested the hypothesis that the invasiveness of Urochloa arrecta (non-native in the Neotropics) is negatively affected by the species richness and abundance of native aquatic macrophytes in freshwater ecosystems. We first created four levels of macrophyte richness in a greenhouse (richness experiment), and we then manipulated the densities of the same native species in a second experiment (density experiment). When the native macrophytes were adults, fragments of U. arrecta were added, and their growth was assessed. Our results from the richness experiment corroborated the hypothesis of a negative relationship between the native species richness and the growth of U. arrecta, as measured by sprout length and root biomass. However, the resistance to invasion was not attributed to the presence of a particular native species with a greater competitive ability. In the density experiment, U. arrecta growth decreased significantly with an increased density of all five of the native species. Density strongly affected the performance of the Poaceae in a negative manner, suggesting that patches that are densely colonized by native macrophytes and less subject to disturbances will be more resistant to invasion than those that are poorly colonized and more commonly subjected to disturbances. Our density experiment also showed that some species exhibit a higher competitive ability than others (sampling effect). Although native richness and abundance clearly limit the colonization and establishment of U. arrecta, these factors cannot completely prevent the invasion of aquatic ecosystems by this Poaceae species.
Hydrobiologia | 2015
Sidinei Magela Thomaz; Roger Paulo Mormul; Thaisa S. Michelan
In this review, we aim to draw parallels between the principal concepts of invasion biology, developed mainly for terrestrial plants in temperate regions, with findings for macrophytes recorded in tropical inland waters. In these ecosystems, the most important abiotic and biotic filters influencing invasion success are related to water and sediment conditions, light, disturbance, hydrology and the diversity and density of native species. The main impacts are related to direct and indirect changes in the populations and communities of native macrophytes and other associated organisms. Non-native ecosystem engineer species of macrophytes can affect ecosystems directly, and after affecting ecosystems, their effects can extend to populations and communities. High plant growth rates in the tropics could lead to rapid invasion and larger impacts compared to temperate ecosystems. Although we found many parallels between ecosystems regarding the general concepts of invasion, areas that should receive further investigation in the tropics include (i) the synergistic interaction of multiple invasive species, (ii) the effects of regime shift on invasion success and vice versa and (iii) how climate change will affect the dynamics of macrophyte invasion in tropical ecosystems.
Brazilian Journal of Botany | 2015
Fabielle M. Bando; Thaisa S. Michelan; Eduardo Ribeiro Cunha; Bruno R. S. Figueiredo; Sidinei Magela Thomaz
Aquatic macrophytes colonize a variety of environments, and they play important roles in ecosystem function and in community structure. One key challenge for aquatic ecologists is to investigate the environmental factors that drive the richness and distribution of these plants. In this study, we assessed the importance of selected morphometric variables and of the canopy openness of the riparian vegetation to explain macrophyte species richness and composition. We sampled macrophytes along gradients of depth, littoral slope, distance from the connection with the river, and canopy openness in floodplain lakes connected with the Upper Paraná River. We used quadrats to survey a total of 40 sites in 11 lakes. We recorded 31 macrophyte species and found that macrophyte richness was best and positively correlated with canopy openness. This correlation suggests that canopy openness plays an important role as an environmental filter, regulating the amount of light availability for macrophytes. Macrophyte species composition was best correlated with depth, indicating that zonation of macrophyte species also occurs in these shallow lakes. These findings emphasize the importance of morphometric variables and canopy openness for structuring macrophyte assemblages. In addition, our results suggest that canopy openness and depth may be considered in management strategies aiming to recover macrophyte diversity and the processes mediated by aquatic macrophytes in small and shallow floodplain lakes.
Acta Limnologica Brasiliensia | 2015
José Vitor Botter Fasoli; Thaisa S. Michelan; Sidinei Magela Thomaz
Aim: To test the invasibility of aquatic ecosystems by an exotic species, we used the invasive macrophyte Urochloa arrecta, which has invaded many Neotropical waterbodies and has reduced biodiversity in these habitats. The extensive growth of this macrophyte can be related to its affinity for mud-rich sediments, which occur primarily in secondary river channels and lentic habitats.MethodsTo test this hypothesis, we cultivated U. arrecta in trays with different percentages of mud and we measured the sprout length and biomass of the plants after 75 days.ResultsOur results showed a positive and significant relationship between sediment mud percentage and nitrogen, phosphorus and organic matter. Both plant length and biomass increased significantly and continuously with increasing mud content, indicating that the growth of this species is not limited even at the highest levels of mud, which is shown to be toxic for other species of macrophytes. Thus, it is probable that sand-rich sites, such as river shores, are less vulnerable to invasion by this species than relatively mud-rich sites, such as lakes.ConclusionsThis finding indicates that relatively mud-rich ecosystems should be prioritised in monitoring programs to prevent invasion by this species. In addition, the slow development of this species in sandy sediments opens a potential window for its management, at least on small spatial scales. However, despite the reduced growth of U. arrecta in sand-rich sediments, this grass is able to grow in several types of sediments, which explains its spread in a variety of habitats in Neotropical freshwater ecosystems.
Freshwater Biology | 2010
Thaisa S. Michelan; Sidinei Magela Thomaz; Roger Paulo Mormul; Priscilla Carvalho
Acta Oecologica-international Journal of Ecology | 2009
Sidinei Magela Thomaz; Priscilla Carvalho; Roger Paulo Mormul; Fernando Alves Ferreira; Márcio José Silveira; Thaisa S. Michelan
PLOS ONE | 2013
Mariana Carolina Teixeira; Sidinei Magela Thomaz; Thaisa S. Michelan; Roger Paulo Mormul; Thamis Meurer; José Vitor B. Fasolli; Márcio José Silveira
Journal of Limnology | 2014
Thaisa S. Michelan; Márcio José Silveira; Danielle Katharine Petsch; Gisele Daiane Pinha; Sidinei Magela Thomaz
Aquatic Ecology | 2015
Louizi de Souza Magalhães Braghin; Bruno R. S. Figueiredo; Thamis Meurer; Thaisa S. Michelan; Nadson Ressyé Simões; Claudia Costa Bonecker
Journal of Applied Ecology | 2017
Heloísa Beatriz Antoniazi Evangelista; Thaisa S. Michelan; Luiz Carlos Gomes; Sidinei Magela Thomaz