Stomach content analysis reveals how urbanization shapes the trophic and taxonomic structure of macroinvertebrate communities in an Andean river

Abstract

Landscape modifications due to urbanization contribute to a decline in biodiversity, resultingin changes in species richness, composition, and the abundance of sensitive and tolerant species.These changes also affect the structural and functional dynamics of biological communities, including trophic roles and functional feeding groups. In this study, we aimed to characterize aquatic macroinvertebrate assemblages in sites with varying levels of human disturbance along a river in San Salvador de Jujuy, Argentina. We assessed both alpha and beta diversity, as well as trophic functional groups based on stomach content analysis. Our findings showed that urban environments significantly reduce macroinvertebrate species richness, particularly in highly disturbed areas. We also found notable changes in community composition, with significant species turnover between sites. Additionally, urbanization altered the functional structure of the community along the river, especially in terms of functional trophic groups, with some species even changing their diets. These results suggest that functional responses, particularly changes in functional groups, may provide valuable complementary insights to traditional diversity metrics when evaluating the environmental quality of rivers.