Banca de DEFESA: ANA CAROLINE BATISTA DA SILVA

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
STUDENT : ANA CAROLINE BATISTA DA SILVA
DATE: 06/04/2023
TIME: 10:00
LOCAL: UFAL - ICBS sala 18
TITLE:

Taxonomic and functional structure of fish assemblages in the continuous river-estuary of the São Francisco River and impact of non-native species

KEY WORDS:

Seasonality. Invasibility. Invasiveness. Modeling. Functional Diversity. Taxonomic diversity.

PAGES: 30
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUBÁREA: Ecologia Aplicada
SUMMARY:

The river-estuarine continuum comprises several highly productive environments related to constant fluctuations in environmental conditions due to the mixing of freshwater and saltwater, creating stratified environments that filter the occurrence of species along its length. The diverse habitats of these transitional aquatic ecosystems have been subjected to intense impacts resulting from the damming of rivers and the introduction of non-native species. In the present dissertation, we approach two questions, having as a model the river-estuarine continuum of the lower São Francisco River, historically impacted by hydroelectric construction and species introduction. For the first question, the response of the taxonomic structure of the fish community to physiographic and seasonal factors related to biological productivity was studied. For the second question, the impact of non-native species on the functional diversity of the community based on high-resolution trophic traits was verified. The continuum was spatially divided into three regions according to the geomorphology of the lower São Francisco: Depression (upper), Tableland (middle) and Lowland (lower). Bimonthly data on composition and abundance by fish species and quantitative diet data were collected between 2019 and 2021 with various fishing gear.

Simultaneously, abiotic data were recorded (salinity, depth, temperature, chlorophyll a, turbidity, conductivity, dissolved oxygen). The results indicate that seasonality, modeled by rainfall variation, does not influence the taxonomic structure of the fish community in the river-estuarine continuum of the São Francisco River. However, spatial differentiation in the composition and use of habitat is defined mainly by salinity. In this sense, the impact of the loss of the seasonal effect in dammed environments was discussed. Regarding the impact of non-native species on the native community of the lower São Francisco River, simulation scenarios of components of functional diversity were used, evaluating the impact on the trophic structure by removing non-native species by physiographic region. Based on the concept of trophic niche partition, high-resolution continuous trophic functional traits were estimated by analyzing the diet of native and non-native species. Non-native species were removed from simulation scenarios based on the trophic level. Ten non-native species were identified with trophic levels ranging from detritivores to carnivores, with occurrence and abundance related to the region along the continuum. The results of the simulations, according to the removal of non-native species from the lowest to the highest trophic level and later recalculating the functional indices, indicate an impact on the functional structure of the native community. From the first removal of the introduced species, there is an expansion in the functional space in the tableland region, making it possible to infer that non-native species compact the trophic niche of the species in this region. In the depression region, functional homogenization occurs. The lowland has an environmental filtering process, with non-native species being barred due to higher salinity. However, despite all the non-native species found being from freshwater, there was a low abundance of Bryconops melanurus, Cichla kelberi, Metynnis lippincottianus, Oreochromis niloticus, Pellona castelnaeana and Trachelyopterus galeatus.

BANKING MEMBERS:
Presidente - 1219840 - NIDIA NOEMI FABRE
Interno(a) - 2265276 - UEDSON PEREIRA JACOBINA
Externo(a) à Instituição - ROSANA MAZZONI BUCHAS
Externo(a) à Instituição - JEAN RICARDO SIMÕES VITULE