Banca de DEFESA: LEONARDO ALMEIDA FREITAS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : LEONARDO ALMEIDA FREITAS
DATE: 23/11/2022
TIME: 09:00
LOCAL: on-line
TITLE:

Taxonomic and functional diversity of ichthyofauna along a gradient of marine influence in a tropical bay

KEY WORDS:

Biodiversity, coastal fish, functional divergence, environmental changes, estuarine areas

PAGES: 60
BIG AREA: Ciências Biológicas
AREA: Zoologia
SUBÁREA: Zoologia Aplicada
SUMMARY:

Understanding the patterns and processes that lead to the distribution of species in the environment is essential to make predictions to protect ecosystems and facilitate the rational exploitation of resources, being one of the most important issues in applied ecology studies. The present study aimed to assess the taxonomic and functional diversity of the ichthyofauna in a tropical semi-enclosed coastal system and to detect eventual spatial changes influencing fish diversity. We also sought to associate differences in fish assemblages with the gradient of marine influence, considering the three zones of the Sepetiba Bay (inner, middle and outer). Fish sampling, using bottom trawls and measurements of environmental variables were performed concurrently, using a standardized protocol in the three zones and four seasons to enable spatial and temporal comparisons. Seventeen quantitative morphological measurements of 5 to 6 adult fish for each species were used to determine 15 functional traits related to food acquisition and locomotion. Three taxonomic diversity indices (Shannon, Simpson and Pielou) and six functional diversity indices (richness, evenness, divergence, dispersion,  originality and specialization) were used. Water transparency and depth were higher in the outer zone compared to the inner zone, whereas pH (lower in winter), salinity (higher in summer compared to spring) and temperature (higher in summer) changed seasonally. An increase in species richness and a concomitant decrease in fish abundance and biomass were observed from the inner to the outer zone, with fish assemblages differing between the three zones. The Shannon and Pielou taxonomic diversity indices were higher in the outer zone, while the Simpson's dominance was higher in the inner zone, and did not differ among the seasons. Six functional groups were distinguished, with one of them (marine catfish) very abundant, predominating in the inner zone, and contributing to reduce the divergence. On the other hand, a very diverse group (richness) was predominant in the external area, contributing to increase the redundancy in this area. Most functional indices were higher in the outer zone, except for functional originality and specialization, confirming the greater redundancy of functional tracts in this zone. However, significant differences were found only for Functional Divergence, which was lower in the inner zone, indicating that less abundant species present more specialized traits. Due to the lower redundancy of functional traits, especially in low abundant species, the inner zone should be prioritized in conservation policies, as the loss of species could affect the ecosystem roles played by them, thus guaranteeing the preservation of functional characteristics as well as the sustainable use of available resources.

COMMITTEE MEMBERS:
Interno - 387200 - FRANCISCO GERSON ARAUJO
Externa à Instituição - HELAINE DA SILVA MENDONÇA - IFRJ
Externa à Instituição - ELLEN MARTINS CAMARA - UFRRJ
Externa à Instituição - MARCIA CRISTINA COSTA DE AZEVEDO - UFRRJ