Aquatic Insect Assemblages of Man-made Permanent Ponds, Buenos Aires City, Argentina

Abstract

Freshwater habitats are important elements within urban green space, and they are endangered by various types of human activity. With the aim to increase the knowledge about species biodiversity in urban ecosystems, we characterized the assemblages of aquatic insects in four man-made permanent ponds in Buenos Aires city (Argentina) during a one year period. The species richness recorded was 32. The most abundant taxa in three ponds were Sigara spp. (Hemiptera) and Chironominae (Diptera), in the other pond were Sigara and Caenis (Ephemeroptera). The removal of aquatic vegetation from the study ponds may affect both the establishment and permanence of the insect community. Swimmers were the dominant group in the studied sites, followed by burrowers and sprawlers, only a few strictly climbers were collected. Accordingly, all the ponds were dominated by collectors (principally gatherers), secondarily by predators and only few shredders were detected, which was much affected by the extraction of macrophytes. Non-parametric abundance indexes estimated a number of species very close to the observed number in each site. Conversely, the incidence indexes estimated more species because there were many more taxa presented only in one sample than those represented by few individual in a sample. The present study contributes with some knowledge that can improve the management of these aquatic urban habitats. Considering that macrophytes affect animal assemblages due to their role as physical structures that increase the complexity or heterogeneity of habitats, they should not be removed by authorities in order to promote biodiversity.