Influence of land use on benthic macroinvertebrate assemblages in headwater streams of the Jaguari River Basin, Brazil

Headwater streams play a crucial role in the formation of rivers; they boast numerous springs and serve as hotspots for aquatic biodiversity within watersheds. However, human activities frequently compromise the health of these environments. Common disturbances include the removal of riparian vegetation, sedimentation in the streambed, and the introduction of pollutants such as pesticides. This study sought to assess the macrobenthic community in three headwater rivers over a 9-month period, examining variations in water quality and community composition across different land uses. Key water quality variables — electrical conductivity and total suspended solids — were elevated at the Extrema (EX) Stream, likely attributable to pasture management practices. The Toledo (TO) Stream had higher water temperature and phosphate levels, potentially linked to the removal of riparian forest and the use of fertilizers in vegetable cultivation, respectively. Regarding the benthic community, metrics such as dominance (D); the percentage of Ephemeroptera, Plecoptera, and Trichoptera (% EPT); the EPT/Chironomidae ratio; and the Shannon–Wiener diversity index (H') revealed a clear gradient in environmental health among the three study sites. The Monte Verde (MV) stream emerged as the most pristine one, followed by the EX and TO sites. These data underscore the deleterious impact of unsustainable agricultural practices. In conclusion, such agricultural activities exert a negative influence on both environmental quality and benthic macroinvertebrate communities in headwater streams. Keywords: biomonitoring, Camanducaia River, EPT, riparian vegetation.