Diversity of algae and cyanobacteria growing in heavy metal-contaminated sites

Abstract

Environmental pollution has become one of the major concerns due to itsdetrimental effects on human health, ecosystems, and how it can affectecological balance and resource availability. Algae and cyanobacteria arepresent in all types of soils. These photosynthetic microorganisms areconcentrated in the topsoil and can be used as bioindicators of contaminatedsoils in ecological monitoring. In this work, heavy metal (HM) contaminated soilsfrom the province of Córdoba were evaluated in order to: a) characterize thecommunity of soil algae/cyanobacteria and b) evaluate the seasonal variability ofthe soil algae/cyanobacteria composition. Soil samples (n = 20) were collectedduring two seasons (summer and autumn) from 3 sites (sites I, II and III) rangingfrom soils with low to high HM content (Pb: 380-14,542 ?g g-1; Cu: 59-3,259 ?g g-1; Zn: 1967-63,323 ?g g-1) and a control site (Pb: 29-73 ?g g-1, Cu: 20-45 ?g g-1, Zn: 116-163 ?g g-1). In the laboratory, the soil was sown in capsules withsterilized Watanabe medium and grown for 9 weeks. The algae andcyanobacteria were identified over time and the final relative abundance wasanalyzed. We identified 17 species of Cyanobacteria, 3 species of Chloroplastidaand 1 species of Herterokontophyta. The number of species was significantlydifferent between the sites, with the most contaminated soil presenting the lowestnumber of soil algae species. Considering the seasons, the number of specieswas not significantly different. The most abundant species were Cyanobacteria;Leptolyngbya fragilis (Gomont) Anagnostidis & Komárek and Kamptonemachlorinum (Kützing ex Gomont) Strunecký predominated in autumn, while insummer were L. fragilis and L. tenuis (Gomont) Anagnostidis & Komárek.Additionally, only L. tenuis was present in the soil with the highest concentrationof HM. Our results indicate that soil algae/cyanobacteria species are adaptedmicroorganisms and should be considered for studies of remediation ofcontaminated soils in Córdoba.