|Support type:||Scholarships in Brazil - Post-Doctorate|
|Effective date (Start):||May 01, 2014|
|Effective date (End):||April 30, 2016|
|Field of knowledge:||Biological Sciences - Zoology - Applied Zoology|
|Principal Investigator:||Alberto Ferreira de Amorim|
|Home Institution:||Instituto de Pesca. Agência Paulista de Tecnologia dos Agronegócios (APTA). Secretaria de Agricultura e Abastecimento (São Paulo - Estado). São Paulo , SP, Brazil|
Large sharks as apex predators are important links between trophic levels, determining the size of levels through direct (predation) and indirect effects (e.g. apparent competition, exclusion competition, risk effects) of predator-prey relationships. In this sense, the decline of large predators populations will lead to increases in populations of intermediate components, consequently leading to the reduction in populations of intermediates' prey. Therefore, understanding the trophic interactions between large sharks, identifying keystone species and detecting which exert top-down and bottom-up effects is fundamental to evaluate the stability and dynamics of ecosystems, especially those who suffer intense fishing pressure. Furthermore, studies of ecological function of sharks together with long-term fishing data can provide information on the fishing impacts on ecosystems. Thus, this project aims to evaluate the importance of sharks in two ecosystems (oceanic versus coastal), located in southeastern and southern Brazil, using two methodologies: 1) Mass-balanced models (with Ecopath software) and 2) topological analyses. Therefore, the questions to be answered are: I) Large sharks are keystone species in the studied ecosystems? II) Through simulations of fishing data, the reductions of large sharks lead to destabilization of the trophic structure in the two ecosystems? III) Both methodologies are compatible for trophic analysis or shows divergent results?