Effect of ecoregion and river type on neotropical Chironomidae (Diptera) from humid mountain to semiarid lowland

PERO, EDGARDO JAVIER IGNACIO; TORREJÓN, SILVIA ELENA; MOLINERI, CARLOS

REVISTA DE BIOLOGíA TROPICAL

REVISTA DE BIOLOGIA TROPICAL

Año: 2023 vol. 71

0034-7744

Introduction: Chironomidae (Diptera) is the most widespread and abundant aquatic insect family in freshwaterecosystems. Chironomids are considered good indicators of water quality but are seldom identified at the genuslevel in broad spatial scale studies.Objective: To identify environmental conditions associated with chironomids in an altitudinal gradient.Methods: We compared ecoregions, river types, and seasons, for chironomids in neotropical streams and rivers(18 river sites; 2014-2018; Yungas rainforest and Western Chaco dry forest, Argentina). We used non-metricmultidimensional scaling, dissimilarity, envfit analysis and rank-abundance curves.Results: Chironomid “assemblages” matched both ecoregions and river types. However, ecoregions presented abetter fit with species composition. The stenothermal taxa of Orthocladiinae were dominant at high elevationsand the eurythermal Chironominae in lowland rivers. Altitude, water temperature and conductivity were important.Seasonal differences were smaller than ecoregional differences.Conclusions: Ecoregions, altitude, water temperature and conductivity correlated with chironomid communities.Orthocladiinae were dominant at high elevations and Chironominae in lowland rivers.Key words: non-biting midges; Tanypodinae; Diamesinae; Podonominae; macroecology, rivers, South America.