Ephemeroptera are bioindicators of water quality and human action near water bodies. In addition, the diversity pattern of these insects can respond to the distance from the source and river banks, as well as the environmental integrity and physical-chemical parameters of the water. In order to verify the effects of human action on the diversity of Ephemeroptera in an Amazonian savanna river, passive collections were carried out in 15 locations between October and November 2020 along the course of the Cauamé River in Roraima. Within each location, two collections were carried out, one on the right bank and another on the left bank, totaling 30 sample units. A Pennsylvania model light trap was used, equipped with white and UV LED lamps, motorcycle battery and plastic container with a capacity of 1 liter of alcohol. In the 30 sampling units within the 15 selected sites, 8,946 individuals were collected, distributed in 7 families and 38 genera of Ephemeroptera. A genus appeared for the first time in the municipality of Boa Vista, Coryphorus (Peters, 1981), increasing the occurrence of this taxon in Roraima. The richness and abundance of Ephemeroptera tended to decrease with distance from the source of the river. However, when analyzing the Odds Ratio, the interaction regarding gender richness was significant. The water course gained eco-hydrological growth as it moved away from the source. This result corroborated the concept of a “continuous river”, which provides for increased productivity along the course of the river. As the stretches of the river widened, the diversity of Ephemeroptera grew, corroborating the concept of “habitat complexity”, where it predicts that the diversity of habitats increases along the longitudinal axis of the river and this increase influenced the patterns of composition and diversity of Ephemeroptera. However, no statistically significant effects of the physicochemical parameters pH and electrical conductivity of the water, the river bank, or the environmental integrity on the diversity of Ephemeroptera were detected. The present work is unprecedented in the region and provides data for future studies and adaptations to the management of the basin.
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