Banca de DEFESA: ARISTON PEREIRA DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ARISTON PEREIRA DOS SANTOS
DATE: 08/09/2025
TIME: 10:00
LOCAL: Google Meet (https://meet.google.com/cjx-mprx-cxg)
TITLE:

THE SILENCE OF THE INVISIBLES: HOW BENTHIC CHANGES AFFECT THE BETA DIVERSITY OF CRYPTOBENTHIC REEF FISHES IN THE FERNANDO DE NORONHA ARCHIPELAGO

KEY WORDS:

Cryptobenthic ichthyofauna; marine substrate; beta diversity; temporal shifts; indicator species

PAGES: 48
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Cryptobenthic fishes (CRBs) are fundamental components of reef biodiversity, playing a key role in energy transfer and ecological stability of coastal ecosystems. However, their small body size and cryptic habits hinder continuous monitoring and the assessment of environmental impacts on this reef fish assemblage. Recent studies have reinforced the importance of this group, which often includes endemic species, especially in oceanic islands, making their conservation even more critical. This study evaluated temporal variations in the density, richness, and composition of CRBs in two distinct periods (2000 and 2023/2024) in the Fernando de Noronha Archipelago, correlating these ecological parameters with benthic substrate structure. Thirteen species from four CRB families (Gobiidae, Blenniidae, Labrisomidae, and Tripterygiidae) were analyzed using standardized visual censuses across 14 sites around the archipelago, with 10 quadrats sampled at each site during four expeditions in 2023 and 2024. In each quadrat, both the number of CRBs and the frequency of benthic substrate occurrence (ordinally categorized as absence, low, medium, and high frequency) were recorded. Current data were compared to a previous study conducted in 2000, enabling the identification of long-term changes and the evaluation of historical trends in reef structure, which are essential for understanding ecological resilience and the cumulative effects of anthropogenic and climatic pressures. Multivariate analyses (PCA, PERMANOVA, NMDS, RDA), combined with GAMLSS models and beta diversity metrics (Whittaker), revealed significant changes in reef substrate cover, with the replacement of reef-building organisms by algal mats and increased abundance of cyanobacteria. These alterations resulted in a reorganization of CRB assemblages, with higher overall abundance, reduced spatial variability, and taxonomic homogenization. Indicator species analysis highlighted the replacement of specialized taxa by more generalist and tolerant species. The results point to a process of structural simplification of reef habitats, driven by anthropogenic pressures and climate change, with direct implications for the resilience and ecological functioning of cryptobenthic fish communities. Furthermore, this research responds to a demand from the Instituto Chico Mendes de Conservação da Biodiversidade (ICMBio), the environmental agency responsible for the management of the area, and provides recommendations for strengthening conservation strategies in the Marine Protected Areas of the archipelago, while underscoring the importance of long-term monitoring and the preservation of microhabitats as fundamental strategies for maintaining functional biodiversity in marine environments.

COMMITTEE MEMBERS:
Externo à Instituição - CLAUDIO LUIS SANTOS SAMPAIO - UFAL
Interna - 1677189 - GISLENE MARIA DA SILVA GANADE
Presidente - 1378974 - LIANA DE FIGUEIREDO MENDES