Anthropause on tardigrade urban communities during COVID-19 pandemic restrictions in Salta, Argentina

The World Health Organization declared COVID-19 a pandemic on 11 March 2020. The 'anthropause' almost emptied our streets of vehicles. In urban areas, automobile traffic is a major environmental factor, and tardigrades can serve as bioindicators of environmental change. During the winter of 2019-2020, samples were taken both before and during the COVID-19 lockdown. In both cases, traffic variables (vehicles per minute), environmental variables, and microhabitats were evaluated. Both before and after the COVID-19 lockdown, the true species diversity and the beta-diversity of each habitat and habitat pair were compared. The indicator value method identified species that served as indicators of habitat. Although species richness increased during the anthropause, abundance decreased, as evidenced by the discovery of previously unknown species of Paramacrobiotus and Milnesium in 2020 and by the first record of Mesobiotus in the same year. Different variables were affected in different ways by the decline in vehicular traffic that occurred during the anthropause. Compared to the other examined traffic conditions, the behaviour of the variables was distinct in medium traffic, resulting in more stable conditions. Patterns of nested urban diversity might produce reversible gradients over time. Between habitats with high vehicular traffic and those with medium vehicular traffic, the greatest loss of species occurs.