Tese de mestrado, Ecologia Marinha, Universidade de Lisboa, Faculdade de Ciências, 2021Mangroves are valued for their role in climate regulation, countering coastal erosion and providing raw materials. Mangroves have diverse fish communities, and the roots of mangrove trees provide shelter for fish species, especially juveniles. Little is known about Santomean mangroves, with 12 mangrove systems identified, from which four were included in this study. This thesis aims to comprehend how fish diversity varies between mangroves with different characteristics, using Santomean mangroves as case study. The environmental conditions found in the smaller systems were more homogeneous than those of the larger systems. Twenty-two species were sampled, with Malanza showing the highest richness and Praia das Conchas the lowest. The functional diversity results suggest that Malanza is more diverse and has a functionally richer community. This higher diversity is probably due to the heterogeneity of environmental conditions and their temporal stability. Angolares had low diversity, with an even but species poor community. Likely due to the environmental variability that only allows tolerant species to establish. The reduced size and depth of Diogo Nunes is probably stunting its diversity. Nevertheless, the fish community of Diogo Nunes is functionally more diverse than that of the larger Angolares system. Pelagic and marine species preferred larger and deeper mangroves, while benthic and estuarine species were predominant in Diogo Nunes. Species and functional diversity were positively correlated indicating complementarity between them and showing that functional diversity adds information about species-environment interactions. Functional and species evenness were not correlated showcasing the importance of the use of both metrics to acquire a more complete understanding of the communities. Taxonomic and functional diversity were negatively correlated indicating that species from different taxa may perform similar functions. From a management point of view this approach represents an advantage as it can identify which systems are more important for which groups, allowing the prioritizing of systems for conservation and management
