Banca de DEFESA: EMERSON SILVA DIAS

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
STUDENT : EMERSON SILVA DIAS
DATE: 28/08/2020
TIME: 14:00
LOCAL: Webconferência Google Meets - meet.google.com/ufs-pkjm-knb
TITLE:

Biodiversity effects on aquatic ecosystem functioning on multiple trophic levels – an observational study.

KEY WORDS:

Efeitos de biodiversidade; diversidade funcional; produtividade; processos ecossistêmicos; fitoplâncton; zooplâncton

PAGES: 70
BIG AREA: Ciências Biológicas
AREA: Ecologia
SUMMARY:

Lakes and reservoirs are essential components for human development and carry out important ecosystem processes. Understanding the mechanisms that determine these processes is necessary in a scenario of climate change and consequent increase in the interdependence between society and natural resources. In lentic ecosystems, the production and transfer of matter and energy are largely carried out by the phyto-zooplankton communities. Diversity effects on ecosystem functioning of (BFE), driven by niche partitioning and selection effects in the community can affect these processes positively or negatively. However, it is necessary to elucidate which components of diversity are most important and what is the shape of the relationship between each function and its predictors, in addition to studies that observe these effects in natural environments. Testing the effects of biodiversity in conjunction with abiotic variables over a wide spatial range provides the necessary support to advance knowledge about BFE to predictive and applied models. The aim of this work was to analyze the relationship between different aspects of phytoplankton and zooplankton diversity on the functioning of aquatic ecosystems in 98 lagoons and reservoirs in the state of Rio Grande do Norte, Brazil. To measure functional diversity, metrics were calculated based on the distance of the functional traits of the communities, generating a functional trait space from which the richness, equitability and functional divergence were analyzed. In the first chapter, the effects of the taxonomic and functional diversity of phyto and zooplankton and the intraspecific functional diversity of phytoplankton over biomass and resource use efficiency of nitrogen and phosphorus were assessed. In the second chapter, the relationship between biomass and resource use efficiency of zooplankton and its relationship with the taxonomic and functional diversity of zooplankton and phytoplankton were analyzed. The effects of diversity were analyzed in regressions in Random Forest models, with selection of variables for the measure of importance, analyzing the partial dependence and the magnitude of the effect (ME) between the diversity and the focal ecosystem function. Significant diversity effects of high magnitude of zooplankton functional divergence for zooplankton biomass (ME = 1.09) and negative effects of taxonomic (ME = -0.4) and functional phytoplankton (ME = -0.77) on the rate of resource use of zooplankton. Phytoplankton functional divergence had a strong positive effect (ME = 0.82) on phytoplankton biomass, as well as phytoplankton functional richness (ME = 0.43) and negative effects of phytoplankton functional equitability (ME = -0.56 ). The nitrogen use efficiency of the phytoplankton community was positively affected by its functional divergence (ME = 0.65). The efficiency of phosphorus use has not been shown to be affected by diversity or environmental variables. The inclusion of intraspecific functional richness did not present good predictive abilities for phytoplankton. Dominance effects on ecosystem functions were observed, indicating selection effects of super-dominant cyanobacteria species and strong effects of functional divergence pointing to niche differentiation in highly productive communities at both trophic levels. Non-linear, positive and negative, effects, were observed between diversity and the functioning of ecosystems on a large spatial scale. Observing these effects in real ecosystems in conjunction with environmental variables confirms predictions made in experimental studies and expands the application of BFE in freshwater environments.

BANKING MEMBERS:
Presidente - 1714892 - ADRIANO CALIMAN FERREIRA DA SILVA
Externa à Instituição - CAMILA RODRIGUES CABRAL
Interno - 1362202 - JOSE LUIZ DE ATTAYDE
Externo à Instituição - RAFAEL DETTOGNI GUARIENTO - UFMS
Externa à Instituição - REGINA LÚCIA GUIMARÃES NOBRE