The relative contribution of environmental and spatial factors on the composition of assemblages of Chironomidae (Insecta, Diptera) in Atlantic Forest springs

Abstract

ABSTRACT Environmental and spatial factors can affect the distribution of aquatic insect metacommunities. In tropical springs, few studies have been conducted on the subject, especially regarding the influence of spatial variables. Our main objective was to assess the influence of environmental and spatial factors on the composition of Chironomidae assemblages in 48 pristine springs in different watersheds in Minas Gerais state, Brazil. This is the first study of the composition of Chironomids assemblages in springs in the Neotropical region. A single time in the dry season, three samples of the substrate at each spring were collected with a hand net. To assess the importance of environmental and/or spatial predictors of the composition of the Chironomidae metacommunities Partial redundancy analysis was performed. The results show that environmental variables explained little of the composition of Chironomids assemblages in Atlantic Forest springs. The local environmental factors selected by the model were dissolved oxygen, conductivity and plant cover, and the spatial factors selected were PCNM 1 and PCNM 6. Most of the variation in the Chironomidae assemblage remained unexplained by the partial redundancy models. Our results suggest the influence of temporal and spatial variables on the structure of metacommunities of Chironomidae in tropical springs.