Banca de DEFESA: MARIA MARCOLINA LIMA CARDOSO

Uma banca de DEFESA de DOUTORADO foi cadastrada pelo programa.
DISCENTE : MARIA MARCOLINA LIMA CARDOSO
DATA : 29/08/2016
HORA: 13:30
LOCAL: Sala de reuniões do Departamento de Ecologia-CB
TÍTULO:

Omnivorous fish lifehistory and its implications for population and community dynamics in tropical lakes and reservoirs

PALAVRAS-CHAVES:

Body size, diet shift, omnivory, sizeselective predation, sustainable fishing.

PÁGINAS: 100
GRANDE ÁREA: Ciências Biológicas
ÁREA: Ecologia
RESUMO:

Predation and competitive interactions are fundamentally dependent on body size. Higher variations in ingestion and metabolic rates occurs for different sizes for a same specie than among species. As well, ontogenetic niche shifts are common. However, only recently, intraspecific variation in body size has been included on studies of competition and predation. This thesis aims to understand the effects of sizeselective predation and intraspecific competition (different scales of foraging and metabolic costs by size) on sizestructure of omnivorous filterfeeding fish on tropics, i.e. Nile tilapia. The first chapter shows empirical results of sizeselective predation by piscivorous fish on Nile tilapia populations on Brasilian lakes and reservoirs. Nile tilapia shows a high mean adult size in the presence of piscivorous fish, and stunted populations in absence of predation. Effects of planktivory and omnivory for different sizes of a same species are show on second chapter. Our results reveals that populations dominated by adults have a stabilizing effect on plankton dynamic with nutrient enrichment, in contrast to population dominated by zooplanktivorous juveniles. The third chapter is a experimental model, where the physiological characteristics with body size of Nile tilapia were described and translated to population level. The model results shows that sizeselective mortality and resource availability for adult are the main factors driving Nile tilapia sizestructure. Higher adult sizes and lower fish biomass are found for high sizeselective mortality and low resource for adults. Only background mortality is not enough to build populations with large adult sizes. Even at high background mortality, the population is dominated by juveniles and small adult sizes. Our model sustain the empirical results of first chapter and indicates the main processes that drive Nile tilapia population dynamics, being a useful tool for management practices.

MEMBROS DA BANCA:
Externo à Instituição - GUSTAVO HENRIQUE GONZAGA DA SILVA - UFERSA
Presidente - 1362202 - JOSE LUIZ DE ATTAYDE
Externo à Instituição - RODRIGO FERNANDES - UFERSA
Interno - 1177742 - RONALDO ANGELINI
Interno - 1764855 - VANESSA BECKER