DRAGONFLIES AS INDICATORS OF THE ENVIRONMENTAL CONDITIONS OF VEREDAS IN A REGION OF CENTRAL-WESTERN BRAZIL

Abstract

Veredas (palm swamps) play a critical role in maintaining the hydrological system and they are considered the cradle of the waters of the Brazilian Cerrado. Currently, veredas are suffering intense human pressure due to the conversion of native landscapes for other land uses as agriculture, pasture and urban environments. Few studies have evaluated the biodiversity of veredas and the current effects of human impact, especially on aquatic communities. Dragonflies and damselflies (Odonata) have excelled as bioindicators of environmental quality and they are increasingly used in environmental monitoring programs. In this study, we evaluate whether loss of riparian vegetation around the vereda areas alters the communities of Odonata and whether the species can be considered bioindicators of these environmental conditions. Our hypothesis is that eco-physiological and behavioral characteristics, such as thermoregulation capacity and oviposition behavior, influence the persistence of species in communities in natural or altered environments. We sampled 25 veredas and classified them into two groups, namely “preserved riparian vegetation” (VRP), when the riparian vegetation surrounding the sampled stretch was 30 meters or more, and “altered riparian vegetation” (VRA), when the vegetation extended for less than 30 meters from at least one of the banks. Our results showed that the composition of the communities in areas classified as VRP was more similar to each other and different from the communities found in the areas classified as VRA. Of the 52 species observed, 11 species responded as indicators for preserved or altered riparian vegetation. Of these species, four were indicative of areas with preserved riparian vegetation and seven were indicative of veredas with altered riparian vegetation. Our results show that the composition of dragonflies and damselflies, and some taxa in particular may be potential indicators of the condition of veredas, and may, therefore, be included in vereda monitoring programs in Central-Western Brazil.