Abstract:
Cryptobenthic reef fishes (CRFs) differ significantly from more conspicuous and mobile coral reef fishes. CRFs are challenging to observe due to their small body size (typically less than 5 cm in length), cryptic behavior, and close association with the benthic environment. These characteristics often lead to their exclusion from traditional reef fish studies, creating a substantial knowledge gap in our understanding of coral reef diversity and functioning. The omission of CRFs conceals up to 50% of fish biomass and up to 40% of fish species on coral reefs. While many coral reef studies aim to understand the ecosystem's functioning as a whole, the lack of knowledge about the ecological roles and relative importance of CRFs has hindered their inclusion in such analyses. Enhancing our understanding of CRFs' roles in coral reef functioning is crucial, particularly in an era of significant anthropogenic impacts on natural ecosystems. The main goal of this thesis is to elucidate the roles of CRFs in coral reef ecosystem functioning. The first chapter proposes a set of specific traits that approximate CRFs' contributions to ecosystem functioning and discusses their implications. The second chapter presents an analysis of CRF community dynamics across three reefs at increasing distances from the shore, sampled across six distinct habitats. This includes assessments of species diversity, density, and standing biomass, alongside models of biomass dynamics potential. Leveraging the species diversity and abundance of the genus Eviota on the surveyed reefs, the second chapter has a second part that explore species-specific habitat and benthic structure usage, emphasizing mechanisms of habitat competitive exclusion between phylogenetically close species. The final chapter explores the diets of a subset of CRF species from the studied sites, comparing diet diversity and relative prey abundance across different habitats and reefs. The dissertation concludes with a synthesis of the findings, offering general conclusions and insights for future research.

Bio:
Lucía is originally from Cali, Colombia, where her passion for marine life and biodiversity began. She developed a fascination for coral reefs ecosystems and the diversity of fishes that inhabit them. Lucía pursued her Master’s degree at KAUST, where she is currently completing her Ph.D.under the supervision of Professor Michael Berumen. Her research focuses on understanding the ecological and evolutionary aspects of coral reef fishes, with a special emphasis on cryptobenthic species that play crucial roles in reef functioning. Throughout her Ph.D. journey, Lucia has utilized a combination of ecological surveys and molecular tools to address questions of biodiversity, species interactions, and ecosystem functions. Her work at KAUST has contributed to the discovery and description of two new fish species from the Red Sea, along with several publications describing different ecological processes on coral reef ecosystems.