Heterogeneidade de habitats e diversidade de Nematoda em recifes tropicais rasos

Abstract

In shallow reef ecosystems, biological diversity is driven by the presence of ecologically diverse habitats. As the physical structure of these habitats becomes more complex, there is a greater supply of different types of refuge, foraging opportunities, and resources linked to high species diversity and abundance. Thus, habitat heterogeneity on the reef is crucial for promoting biodiversity. However, frequent and intense global and local threats are causing rapid changes in the coverage of these ecosystems, leading to habitat loss and the decline of species that directly contribute to ecosystem functioning and ecological services. One alternative to assess the contribution of reef habitats and associated communities is the use of functional diversity of groups that play significant roles in the ecosystem. Free-living Nematoda have a diversity that can serve as a link to investigate complex interactions between biological diversity and the functional balance of ecosystems, mainly due to their different and important ecological roles. Responses to the influence of different shallow reef habitats on the taxonomic and functional structure of Nematoda were evidenced in this dissertation over two chapters. In the first chapter, the results indicated that the reef flat presents a unique assembly, more taxonomically and functionally diverse, with differences compared to adjacent pool assemblages. These differences are dominated by replacement processes. Dominant Functional Entities (FEs) exhibited combinations of characteristics related to environments disturbed by humans, suggesting that the studied coral reef systems are undergoing degradation and that the functional attributes of Nematoda may be a sensitive tool to investigate disturbances in coral reef ecosystems. In the second chapter, Nematoda showed taxonomic and functional differences among the habitats studied, resulting in 4 groups among the 7 habitats, and the differences were also dominated by replacement processes, with high specificity and fidelity of genera and EFs to habitats. Assemblages showed low functional redundancy and high vulnerability, with most FEs composed of a single genus. These results point to the importance of maintaining habitat heterogeneity in preserving the taxonomic and functional diversity of coral reefs and, consequently, the functions and services associated with this ecosystem.