Long-term manganese exposure-mediated benthic diatom assemblage in a subtropical stream: Distribution, substrate preferences and Mn-tolerance

Benthic diatoms play an important role in the biogeochemical cycle and energy flow of the freshwater ecosystem. In the present study, the benthic diatom samples were collected in a stream impacted by manganese-mining and smelting activities in dry season and rainy season. The DNA sequencing (18s) and morphological analysis were used to explore the distribution, abundances, diversities, and habitat preference of diatoms species. Among the identified 11 families, 31 genera and 116 species of the benthic diatoms, Navicula, Diatoma, Nitzschia and Gomphonema were found dominant in two samplings. In respect of the Alpha diversity, the evenness of diatoms on roots were generally higher than that on stems of plants and the Shannon index (H) values of benthic diatoms on rock and stem of Paspalum paspaloides showed less seasonal change. The Beta diversity revealed that the highest similarity of diatom community compositions frequently occurred on plant roots. Three randomly isolated diatom strains, namely Nitzschia palea DSN01, Nitzschia amphibia DSN02 and Sellaphora seminulum DSS01, were recorded to be able to tolerate Mn(II) exposure at about 50 mg/L. Our findings constitute a major advance in our understanding of the ecology of diatoms impacted by Mn-containing effluent, and have potential implications for the development of strategies to preserve the benthic diatoms and the ecosystem functions they provide. [Display omitted] •31 genera and 116 species of diatoms were identified in the Mn contaminated stream.•Different substrate surfaces defined the community structure of diatoms.•Diatom diversity on rocks and stem of P. paspaloides showed less seasonal change.•Water quality indicated by Shannon index was consistent with the monitoring result.•The randomly isolated diatoms tolerate Mn(II) stress and show Mn oxidation ability.