Agriculture impacts benthic insects on multiple scales in the Eastern Amazon*

Brazilian Amazon is facing ongoing threat due to deforestation. Eastern Amazon (EA), however, is an old colonization front, where rural landscape is dominated by secondary vegetation (capoeira) and cattle ranching. The effects of land-use land-cover (LULC) at catchment, riparian and local scales upon stream insect assemblages (SIA) were analyzed from 17 catchments. Agriculture development, daily variation in temperature, dissolved oxygen and sodium concentrations explained variations of 33.7% in taxa composition and 58.5% in functional feeding groups. Partial Least Squares Regression revealed complex effects on SIA, pointing to interactions of LULC at all scales, but stronger at the riparian. Capoeira placed varied effects upon SIA, positive and negative and weaker than agriculture or forest cover. In order to warrant optimal conditions to the stream biota, indicating a sustained flow of ecosystem services, both forest fragments and capoeira patches should be adequately managed, especially along and closer to the aquatic habitat network.

Automated summary

The study analyzed the impact of land-use and land-cover changes on stream insect assemblages in the Eastern Amazon region, finding that factors such as agricultural development, temperature variations, dissolved oxygen, and sodium concentrations can affect both the species composition and functional feeding groups of stream insects.