Proposta de índice de integridade ambiental aplicado a riachos de mata atlântica e aplicação de teste de validação com parâmetros da assembleia de peixes

Abstract

Considering that most Brazilians streams have suffered intense pressure from human activities, the need to adapt methods for assessing environmental quality becomes essential. In this context, given the dynamics and complexity of the environment, it is essential to use indexes in order to compile a large volume of information, facilitating a holistic view without missing the robustness of individual data. Therefore, in order to propose the creation of an environmental integrity index of Atlantic forest streams, as well as compare the differences of indices generated from different ichthyofauna assessment methods (manual and electric), nine assessment sites belonging to three distinct sub-basins (Cambé, Cafezal and Taquara) were studied, all of them belonging to Tibagi River Basin in the Londrina region. There were tested 50 potential metrics with data of fish populations, limnology, sediment characteristics and structure of riparian forest. From a correlation matrix and principal component analysis of the following metrics were selected for manual fish sampling: Simpson’s dominance, Evenness of Pielou, Percentage of nektonic species, Percentage of Characiformes and Siluriformes, Forest density, Percentage litter cover, Basal area, and Electrical Conductivity. For electric fish assessment, the Equitability nektonic species and percentage metrics were replaced by Percentage of benthic species, while other attributes remain the same. The index of environmental integrity created indicated that the three points of Ribeirão Cambe are poor (in both methods), point 1 of Ribeirão Cafezal is poor (in both methods) point 2 of Ribeirão Cafezal is poor, (for manual) and intermediate (for electrical) while item 3 is intermediate (for manual) and good (for electrical). While points 1 and 2 of Ribeirão Taquara showed up intermediary and point 3 as well, for both methods. Finally, was applied a validation test of the calculated results with general patterns of diversity, IndVal Curve and ABC index, being found consistency between the results suggesting good acceptability to the proposed index.