ISÓTOPOS ESTÁVEIS E OUTRAS FERRAMENTAS EM ESTUDOS TRÓFICOS DE PEIXES EM RIACHOS TROPICAIS

Abstract

Stable isotope analysis (SIA) has become an essential tool in Ecology, being increasingly used in studies of fish in tropical streams. The SIA allows to reconstruct the animals' diet and its intraspecific variation, to trace the contributions of the main basal resources throughout the food web, to calculate trophic position and trophic niche, including niche overlap and its alterations, and to build food webs. The SIA is also used to understand the impact of environmental changes on fish communities and other aquatic organisms. The number of such studies is increasing in Brazil, but there are still several gaps. In this study, we present the basic concepts on stable isotopes analysis in trophic studies of stream fish - especially those of carbon, nitrogen and hydrogen - their premises, uses and limitations, presenting examples from tropical streams. We also explore new conceptual tools in this area, still not used for stream fish in Brazil, such as fatty acids, stable isotopes in specific compounds, nutritional geometry and ecological stoichiometry concepts such as the Threshold Elemental Ratio.