Banca de QUALIFICAÇÃO: MARIANA RODRIGUES AMARAL DA COSTA

Uma banca de QUALIFICAÇÃO de DOUTORADO foi cadastrada pelo programa.
DISCENTE : MARIANA RODRIGUES AMARAL DA COSTA
DATA : 08/10/2018
HORA: 15:30
LOCAL: sala POP-RNP no centro de convivência da UFRN
TÍTULO:

Mixotrophy as an important phytoplankton functional trait in eutrophic
reservoirs

PALAVRAS-CHAVES:

Precipitation; Drought; Grazing; Mixotrophy; Cyanobacteria; Cryptophyceae; light availability; Flow Cytometry

PÁGINAS: 60
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
RESUMO:

Precipitation events and water level fluctuations are environmental factors that affects aquatic ecosystem functioning influencing phytoplankton dynamic and biogeochemical cycle. Nutrient availability and trophic state of arid and semi-arid regions are controlled by quantity and rain periodicity. Future climate scenario predicts an increase in intensity and frequency of droughts in semi-arid regions. Drought leads to water level reduction and consequently increase nutrients concentrations, turbidity, salinity and conductivity, favoring cyanobacteria blooms. However, recent studies shows that mixotrophic algae can be better competitors under more extreme conditions. Mixotrophic organisms play important role as producers and consumers reflecting in the structure of food webs. In this work, we evaluate the effect of precipitation gradient under the structure of phytoplankton community based on a trait-based approach. We confirm the hypothesis that in dry period the main phytoplankton traits are related to a high cyanobacteria biomass (nitrogen fixation, filaments, coloniality), however, in extremely drought periods with critical water level leads to dominance to mixotrophic algae. To confirm that the reduction on light availability caused by sediment resuspension was the main factor on phytoplankton pattern, we performed laboratory experiments with competition between two phytoplankton species (one cyanobacteria and one mixotrophic), manipulating light and sediment addition in systems with high levels of nutrients. Besides this, we also performed grazing experiments to estimate bacterivory by flagellate algae in distinct light and nutrients conditions and propose new methodologies to facilitate ingestion rates quantification. Our study shows the importance of freshwater mixotrophic algae in eutrophic environments and assist in knowledge for bacterivory quantification.

MEMBROS DA BANCA:
Externo à Instituição - HUGO MIGUEL PRETO DE MORAIS SARMENTO - UFSCAR
Interno - 2412921 - JULIANA DEO DIAS
Externo ao Programa - 233.792.888-88 - KEMAL ALI GER - UFRN
Presidente - 1764855 - VANESSA BECKER