Sensitivity variations on soil health indicators related to arbuscular mycorrhizae in a highly disturbed urban basin of Buenos Aires, Argentina

The Matanza-Riachuelo river basin (MRB) is considered one of the most polluted sites in the world, with very high levels of heavy metal(loid)s (HMs). However, as in almost all urban basins, studies on biological indicators of soil health are limited. In this work, we explore the potential of arbuscular mycorrhizal fungi (AMF) diversity, plant mycorrhizal status, and glomalin-related soil proteins (GRSP) concentration as bioindicators of soil health. We sampled three regions of the MRB: upper, middle and lower basins. The highest concentrations of HMs were detected in the lower basin, because it is exposed to a high input of pollutants and anthropogenic impact. Community composition and diversity were compared across the different soil samples. The Glomeraceae family was the most represented in the MRB, and Rhizoglomus intraradices was the only AMF species detected at every sampled site. This work constitutes the first report of 8 of the 16 AMF species described so far in the MRB. GRSP differences were strongly related to HMs concentrations. Both AMF species richness and GRSP concentrations were reliable biological indicators of soil health; while GRSP increases with soil toxicity, AMF richness decreases with soil disturbance.