Dinâmica do molusco invasor Corbicula largillierti (Philippi, 1844) (Bivalvia, Cyrenidea) em ecossistemas dulcícolas: abordagem sobre sua distribuição geográfica e fatores direcionadores

Abstract

Corbicula largillierti (Philippi, 1844) is an Asian bivalve with successful establishment in freshwater ecosystems worldwide. It exhibits high phenotypic plasticity, which enables the species to easily adapt to different environmental conditions, along with an efficient reproductive strategy. Its introduction into new environments often results in negative impacts on native biodiversity, ecosystem functioning, provision of ecosystem services, as well as affecting the economic, social, and human health systems. The main objective of the present study was to evaluate the dynamics of the non-native mollusk C. largillierti in semi-arid river basins and determine its current distribution status worldwide. For this purpose, this dissertation was structured with two chapters: the first deals with the survey of the current distribution of C. largillierti worldwide, including determining the level of species expansion. In this chapter, a global distribution map was constructed through extensive bibliographic research in different databases. Additionally, we included in this study a dataset from two river basins located in the Brazilian semi-arid region: the Pajeú River basin – PJRW, in the state of Pernambuco, and the Paraíba River basin – PBRW, in the state of Paraíba, Northeast Brazil. In PJRW, the Barra do Juá reservoir was selected. In PBRW, three reservoirs were sampled: Camalaú, Epitácio Pessoa, and Sumé. Sampling of environmental and biological variables was conducted in December 2021 in PBRW and in June 2022 in PJRW, both during the dry season of the region. A total of 61 sampling sites were included in the dataset. We recorded for the first time the presence of the non-native mollusk in PJRW, as well as its expansion in the PBRW basin and globally. Regarding its global expansion, our findings indicate that C. largillierti has expanded its distribution in 14 countries, across four continents. The data also demonstrate that the species' widespread distribution occurs in South America, mainly in Brazil and Argentina. The second chapter of the dissertation aims to analyze the direct and indirect hierarchical effects of abiotic factors (physical and chemical parameters of water, habitat, and landscape) and biotic factors (abundance of the non-native invasive mollusk M. tuberculata and richness of the native macroinvertebrate community) on the abundance of C. largillierti. We used the Structural Equation Modeling (SEM) approach. The results obtained in the second chapter indicate that the abundance of C. largillierti was not significantly affected by the abiotic variables included in the model. In contrast, biotic parameters are shown to be factors with a direct and positive effect on the abundance of the non-native bivalve. This suggests that the biotic relationships established in the new invaded habitat may play a more relevant role in the establishment of C. largillierti than local environmental conditions. The results gathered in this dissertation provide valuable insights into invasion processes and the impacts that inter-basin integration projects may have on the establishment of species with invasive potential, such as C. largillierti. Such information can support knowledge for the development of more robust management models, adopting measures for the surveillance and prevention of invasive species, ensuring the maintenance of native communities, integrity, and provision of ecosystem services.