Aspectos da biodiversidade íctia e vulnerabilidade de estuários tropicais em Pernambuco, Brasil

Abstract

The main objective of this thesis was to describe the estuarine ichthyofauna of the State of Pernambuco, considering classical indicators of diversity, complemented with techniques that evaluate functional diversity. Additionally, with a case study, the vulnerability of the main species captured by block net was evaluated through the methodology of Productivity and Susceptibility Analysis (PSA), which is based on biological productivity, related to the life characteristics of a stock, and the susceptibility of organisms to be caught by a particular type of fishing gear. For this study, data were collected quarterly between October 2012 and December 2014 in the estuaries of Itapissuma, Suape, Sirinhaém and Rio Formoso; Using active (beach seine) and passive (block net) fishing gear. A total of 48,754 individuals belonging to 122 species, 80 genera and 36 families were sampled. The diversity indexes, through the indexes of dominance and evenness, revealed that despite Itapissuma has a great diversity of species, its species are taxonomically closer when compared to the other estuaries. In relation to the functional diversity, Suape, Sirinhaém and Rio Formoso, had the lowest levels of functional diversity Q and species richness S, with species very close in the functional typology, which can be related to the fact that the areas are geographically close and present similar physical characteristics. The opposite was observed for Itapissuma, which presented functionally distant individuals, a factor associated with environmental characteristics, such as muddy substrate and high incidence of mangrove, which provide a greater diversity of habitats and a fish assemblage with species morphologically distinct from the other three estuaries. For the vulnerability, the species belonging to the family Centropomidae and Lutjanidae were classified as high-risk species, being highly vulnerable to fishing gear (in this case, block net), given the life history characteristics - species with relatively large size and high longevity - and the greater susceptibility, especially considering the high percentage of juvenile capture. Studies combining the use of diversity indexes, as well as those relating ecological and biological patterns, provide us with a better understanding of the state of fish assemblages as well as their ecological patterns.