Diatom Communities as Bioindicators of Human Disturbances on Suburban Soil Quality in Arid Marrakesh Area (Morocco)

Abstract

Diatoms, unicellular siliceous microalgae, are one of the most known groups of eukaryotic algae, commonly used as bioindicators for assessing water quality in aquatic ecosystems. Conversely, studies on terrestrial diatoms as potential bioindicators of soil quality are rather scarce. This study aims to assess the arid suburban soils quality of Marrakesh disturbed by various anthropogenic activities using diatom communities as bioindicators. The sampling of soil and physicochemical measurements were carried out at six sites with different land use. A total of 26 diatom taxa has been identified with 13 genera. The highest species richness and algal biomass were recorded in agricultural irrigated soils with treated wastewater dominated by pollution-tolerant species of Nitzschia (71.43%). In canonical correspondence analysis, suburban soils were subdivided into three groups depending on the chemical properties and diatom composition. The diatom diversity was significantly correlated with the total organic carbon (TOC), P-PO4, and N-NH4+ contents. While diversity and biomass were significantly lower in the soils affected by municipal and mining solid wastes, the input of organic matter and nutrients from treated wastewater appears to have a positive impact on the soil microflora and its richness. This first exploratory survey showed that diatom communities were more sensitive to the anthropic disturbances on urban soil and could be used as bioindicators of the quality and soils conditions.