Preliminary analysis of urban tardigrades of Rafaela, a medium sized city in the province of Santa Fe (Argentina)

ROCHA, A. M.; CLAPS, M. C.

Simposio; 12th International Symposium on Tardigrada; 2012

The Knowledge of the tardigrades fauna inhabiting in the Neotropical region cities is poorly known. A study on the composition, structure and diversity of tardigrades communities was carried out in Rafaela, a medium sized city of Santa Fe province, in december 2008. In the study area five sites were selected with different traffi c intensities: urban areas with high, middle and lower traffic,industry and surrounding rural areas as well. For each site type, three sites were selected and in each site, three trees. From each of them nine subsamples of lichens and/or moss, 11 mm in diameter, were taken with cylindrical steel cores. The diversity, density and relative abundance of tardigrades were recorded. Statistical and multivariate analyses (CCA) were driven. The  tardigrades were present in 93% of the samples, a total of 2756 specimens were indentifiedwithin 6 genera: Echiniscus, Milnesium, Macrobiotus, Paramacrobiotus, Minibiotus and Ramazzottius. Density ranges varied between urban and rural sites, being maximum at high traffic sites. The number of genus per sample ranged from 1 to 4 and per site between 4 to 5. The maximun number of genus was found at the rural site and the abundance was maximum at the high traffic site. Species of Macrobiotus and Echiniscus were most frequent. The genus Macrobiotus dominates in all sites, except in industrial sites, where Echiniscus was dominant. The genera Ramazzottius and Minibiotus are uncommon in the city, but they were only present in industrial and rural areas respectively but always very few specimens. Milnesium and Paramacrobiotus are present in all sites. In the city of Rafaela, the species richness found in sites exposed to traffic exceeds the estimated for the other cities of Argentina (Santa Rosa, General Pico, La Plata). The Macrobiotus species complex behaves as highly poleotolerantes whereas Echiniscus rufoviridis manifests a medium--low tolerance to urbanization. Future analysis will allow to answer objectives more especifi cally about the spatial-temporal distribution of tardigrades in urban ecosystems.