Recovery of Soil Protozoan Community Structure Promoted by M. sativa After a Strong Pulse of Hydrocarbon Contamination
2020
Mondragón-Camarillo, Laura | Zaragoza, Salvador Rodríguez | Mendoza-López, Ma Remedios | Cabirol, Nathalie | Macek, Miroslav
The response of soil microbiota to hydrocarbon contamination has been studied normally several months after the event. However, as those studies represent a “long-term” context for microbial processes, since protozoa succession can be achieved after 28 days, we wonder how fast does trophic structure of ciliates and flagellates recover from a strong pulse of petroleum contamination under the influence of Medicago sativa. We hypothesized that the root effect of M. sativa would promote faster recovery of the protozoan trophic structure, in comparison with the level reached in unplanted microcosms. The abundances of individuals, species, and trophic groups of ciliates and flagellates were determined at 1, 7, 14, and 30 days after a single pulse of 50,000 ppm of light petroleum on soil microcosms unplanted and planted with M. sativa, and their respective controls. Protozoan diversity and trophic groups were strongly reduced immediately after the pulse of contamination. Ciliates and flagellate trophic diversity increased steadily in all microcosms after 7 days. However, unplanted contaminated and planted contaminated microcosms remained the poorest communities and reached full recovery of trophic groups after 30 days. Also, the protozoan communities were segregated into 2 groups: the first from petroleum and the second formed by non-polluted microcosms. These results suggest that petroleum is a strong selection factor leading to an alternative protozoan community composition and the root effect of M. sativa promotes faster recovery of ciliate and flagellate communities after a devastation produced by a strong pulse of petroleum contamination.
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