Banca de DEFESA: MARIANE AMORIM ROCHA

TAXONOMY AND STRUCTURE OF THE ROTIFERA ASSEMBLY IN COASTAL ECOSYSTEMS IN THE METROPOLITAN SECTOR OF SALVADOR (BA)

Limnic Rotifera, Marine Rotifera, Spatial and seasonal distribution, Ecology, Brazil

Coastal ecosystems comprise ecologically very distinct environments, ranging from sandbanks and lagoon to coral communities. In addition to the complexity and diversity of natural communities, these ecosystems process the flow of nutrients, sediments and water, also providing a wide range of ecosystem services. Taxonomic and ecological studies on Rotifera in coastal ecosystems in Brazil are scarce. Therefore, in this thesis five independent approaches are presented on the Rotifera assemblage, namely: a literature review (Chapter I), three chapters on coastal lagoon assemblages in sandbank habitats (Chapters II, III and IV – dune and coastal lagoons of the Abaeté System, BA) and the last one referring to rotifers in coral communities (Chapter V – Todos-os-Santos Bay, BA). Chapter I describes a comprehensive review of Rotifera and the environmental forces that affect the group in limnic ecosystems. Chapter II focuses on the Rotifera assemblage in 11 lakes coastal and involves an analysis of biotic and abiotic parameters on the structure of the group, and spatial and seasonal patterns. In this Chapter, it was verified that the spatial and seasonal heterogeneity does not significantly affect the abundance and biomass of Rotifera. On the other hand, diversity (H') and evenness (J') presented distinct patterns: H' varied significantly with spatial and seasonal distribution while J' diverged only in spatial distribution. The nMDS (Non-metric Multidimensional Scaling) revealed a trend in spatial clustering. Among the variables presented by the RDA (Redundancy analysis), nitrate, nitrite and phosphate were nutrients that most influenced the assemblage composition. Chapter III aims to describe a new species of Lecane, including an ecological characterization of the lagoons of the Abaeté System and data from the interstitial environment of the hypolentic zone (up to 30 cm deep). The last species of Lecane, an abundant genus generally associated with aquatic macrophytes, was described in the country more than two decades ago. Thus, the scope reached by the analysis contributes to the knowledge of the biodiversity of the rotifers of Brazil. Chapter IV presents the results of the biodiversity and spatial distribution (depths and distances) of rotifers in interstitial waters of the hypolentic zone associated with a shallow lagoon with an acid profile. The abiotic variables that influence the local distribution of the group were identified. The abundance and biomass of rotifers varied significantly in relation to depth – i.e., values were higher in the more superficial ranges. The highest diversity (H'), evenness (J') and lowest dominance (D) indices were observed at 30 cm from the surface and 1.5 m away from the lake shore. Only Bdelloidea had indication index (IndVal) for both, depth and distance. In addition, the assemblage structure responded directly to pH, temperature, electrical conductivity, ammonia-N, dissolved inorganic nitrogen and chlorophyll – a. Finally, Chapter V was dedicated to marine rotifers in coral communities in Todos-os-Santos Bay. An inventory of benthic-periphytic species associated with algae, coral and sponges was developed. As result, three new occurrences of rotifers (2 Bdelloidea and 1 Monogononta) for the coast and two new occurrences of Bdelloidea for the Atlantic Ocean were reported. In fact, there is a huge gap in the global knowledge of marine rotifers, and no data in the literature points out to the diversity of these organisms for Brazil in these environments.