Effect of urbanization on the communities of Tardigrades in Argentina

Abstract

Urban tardigrades are studied little worldwide. In Salta (Argentina), two studies have evaluated their diversity in an urban-native gradient. Vehicular traffic in Salta city has increased over the last decade, increasing environmental pollution. Our aim is to determine whether biotic homogenization occurs in this city. Sampling sites were selected considering different vehicular traffic intensities (high, medium and low). Tardigrades were sampled from bryophytes growing on tree trunks. Specimens were treated according to the usual study methodology. Different biotic and environmental abiotic variables of the microhabitat were considered. A total of 3049 specimens of 16 species of heterotardigrades and eutardigrades were reported. The low vehicular transit habitat was more diverse than the others. Ordination analyses evidenced a nested pattern in the studied urban habitats. Milnesium sp. nov. 3 and Minibiotus sp. nov. 1 were reported as detector species for habitats with medium vehicular traffic. The partition of the β diversity showed that the species turnover was higher among low and high vehicular traffic communities than medium, whereas a loss of species was evidenced between high and medium habitats. The high diversity of tardigrades in Salta city and their assemblages are partly dependent on several factors, including vehicular traffic.