Effect of environmental and microhabitat variables on tardigrade communities in a medium-sized city in central Argentina

Urban ecosystems are dynamic and complex, with human disturbances that lead to biotic homogenization. We consider the changes suffered by the diversity of tardigrades in Santa Rosa city (Argentina) under different intensity of vehicular traffic (high, medium and low), evaluating whether there are biotic and abiotic factors that can influence the structuring of their communities. Moss and lichen samples were extracted and studied, and different environmental variables, microhabitat, and substrate were measured. Eight species were recorded. Habitat with high vehicular traffic contained the highest tardigrade abundance; while low vehicular traffic had the highest species richness. The assemblages of the three urban communities were different, with a strong dominance of three species: Milnesium quiranae, Ramazzottius oberhaeuseri and Macrobiotus kristenseni. Milnesium kogui turned out to be an indicator species for high vehicular traffic community. Ordination analysis showed a nesting pattern in the studied urban habitats, showing a high turnover of species in the high vehicular traffic community, while in medium vehicular traffic community a high nesting. There was a high loss of species in habitat with low vehicular traffic, while in the habitat with medium and high vehicular traffic there was a high turnover of species. The observed nesting pattern could be explained by the loss of microhabitat due to the replacement of urban trees.