Banca de QUALIFICAÇÃO: LIDIANE GOMES DE LIMA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
STUDENT : LIDIANE GOMES DE LIMA
DATE: 10/03/2021
TIME: 09:00
LOCAL: on-line
TITLE:

Assembly ichthyoplankton communities in two tropical estuaries in the Brazilian semiarid region

KEY WORDS:

Recruitment, environmental gradients, spawning, habitat quality

PAGES: 78
BIG AREA: Ciências Biológicas
AREA: Zoologia
SUBÁREA: Zoologia Aplicada
SUMMARY:

 

Estuarine ecosystems are recognized for their functions as nurseries, migration routes, feeding and protection for the early stages of a variety of fish species. Studies on the distribution patterns of the ichthyoplankton community within the estuarine ecosystem are of great relevance for understanding the utilization of the estuarine environment by species to complete their life cycle, through interactions with the abiotic environment and biotic relationships between different ontogenetic stages. The present study aimed to evaluate the spatio-temporal variation of ichthyoplankton density, richness and diversity in relation to variations in local environmental and landscape characteristics of two tropical estuaries with different anthropic pressures. The study was carried out in the estuaries of the Paraíba do Norte River, located in a densely populated area with visible signs of environmental degradation, and in the estuaries of the Mamanguape River, located in an environmental protection area, in Northeastern Brazil. The hypothesis tested was that precipitation is the main predictor variable on the structure of ichthyoplankton communities along the estuarine gradient. This is due to the fact that variations in the hydrological cycle, through increased freshwater input into the system, can promote an increase in habitat quality making the environment more tolerable for the establishment of fish larvae, maximizing their nursery functions. Sampling occurred in three zones along the main channel of both estuaries, with horizontal subsurface trawls accompanied by the measurement of environmental parameters, during the annual cycle between 2018 and 2019. The spatial and temporal variation of the larval assemblages along the main channel of both estuaries were determined by a sequence of environmental variables, highlighting the temperature, transparency, chlorophyll-a and concentration of nutrients, which were influenced by the variations of the cycle hydrological, with precipitation as the driver of species distribution and spawning processes. Larval density was highest during the wet season in both estuaries, indicating the importance of this period for estuarine ichthyoplankton dynamics. The lower rainfall combined with the higher chlorophyll-a concentrations during the dry season favored the establishment of marine species, crucial to the increase in species richness and diversity along the Mamanguape River estuary. On the other hand, in the Paraíba River estuary there was a reduction in species richness and diversity during this same season. This may be associated with the higher concentrations of pollutants recorded and the agricultural and dredging activities that contributed to the decrease in habitat quality impacting the ichthyoplankton community in this estuary. In this study, the representatives of the Marine Estuarine Dependent (MED) ecological guild were the most numerous, with the Engraulidae and Clupeidae as the main species. This abundance of estuary-dependent species emphasizes the importance of these ecosystems as nursery areas.

BANKING MEMBERS:
Externa à Instituição - ANA CRISTINA TEIXEIRA BONECKER
Interno - 387200 - FRANCISCO GERSON ARAUJO
Presidente - 387289 - ILDEMAR FERREIRA
Interno - 1728466 - JAYME MAGALHAES SANTANGELO