Banca de DEFESA: TAMIRES PASCOAL DOS SANTOS

Uma banca de DEFESA de MESTRADO foi cadastrada pelo programa.
DISCENTE : TAMIRES PASCOAL DOS SANTOS
DATA : 07/08/2020
HORA: 09:00
LOCAL: virtual
TÍTULO:

INFLUENCE OF HUMIC ACIDS IN THE AQUATIC HYPHOMYCET COMMUNITY COMBINED WITH NUTRIENT CONCENTRATIONS AND pH VALUES

PALAVRAS-CHAVES:

decomposing microorganisms, humic substances, leaf decomposition, physical-chemical parameters, black water

PÁGINAS: 63
GRANDE ÁREA: Ciências Biológicas
ÁREA: Microbiologia
SUBÁREA: Biologia e Fisiologia dos Microorganismos
ESPECIALIDADE: Micologia
RESUMO:

Aquatic hyphomycete fungi are primary responsible for the process of decomposition in the allochthonous organic matter in headwater streams. Black waters streams have low leaf decomposition rate, fungal biomass and reproductive diversity of aquatic hyphomycetes. We hypothesize that the rates of fungal decomposition and colonization are low due to the low concentration of nutrients, acid pH and higher concentration of humic acid in these streams. In a microcosms conditions we tested a complete factorial design (3 [humic acid levels: 5 and 24mgL^-1] x 2 [nutrient levels: 0.05mgL^-1 nitrogen and 0.07mgL^-1 phosphorus and 0.5mgL^{- 1} of nitrogen and 0.7 mgL^-1 of phosphorus x 2 [two pH ranges: 4 and 7.8] + 3 [controls: river water] x 3 replicates). Senescent leaves of Miconia albicans were incubated in fine mesh bags for 15 days in 3 clear water streams for colonization by aquatic hyphomycetes. In the laboratory, a set of 10 discs from the pre-colonized leaves, for each incubation stream, was distributed in each treatment. Every three days the nutrient solution containing the suspension spores was changed and preserved in formalin (4%) to determine the richness, density and reproduction rate of the aquatic hyphomycetes. We identified 15 species of aquatic hyphomycetes associated with leaf litter in breakdown process. Flagelospora curvula, Lunullopora curvula and Triscelophorus monosporus were the most abundance organism in conidia production. Nitrogen was the main factor that drive fungal biomass, fungal sporulation density and richness, but not leaf litter breakdown. Statistical models suggest that higher concentrations of humic acid, low nitrogen availability and acidic pH negatively affect the leaf decomposition process and alter the aquatic hyphomycete community. Although, our study was carried out in vitro, new hypotheses about the decomposition process in black waters of tropical Brazilian savannah may note future investigations in this unique ecosystem, mainly to understand the interactions between humic substances and aquatic hyphomycetes.

MEMBROS DA BANCA:
Presidente - 1658906 - ADRIANA OLIVEIRA MEDEIROS
Externo à Instituição - PATRICIA FIUZA - UFRN
Externo à Instituição - PAULA BENEVIDES DE MORAIS - UFT