Benthic microbial diversity trends in response to heavy metals in an oxygen-deficient eutrophic bay of the Humboldt current system offshore the Atacama Desert

Ana Zárate, Cristina Dorador, Jorge Valdés, Verónica Molina, Gonzalo Icaza, Aldo S. Pacheco, Alexis Castillo

Research output: Contribution to journalArticlepeer-review

Abstract

Mejillones Bay is a coastal ecosystem situated in an oxygen-deficient upwelling area impacted by mining activities in the coastal desert region of northern Chile, where conspicuous microbial life develops in the sediments. Herein, heavy metal (loid)s (HMs) such as Cu, Pb, As, Zn, Al, Fe, Cd, Mo, Ni and V as well as benthic microbial communities were studied using spectrometry and iTag-16 S rRNA sequencing. Samples were taken from two contrasting sedimentary localities in the Bay named Punta Rieles (PR) and Punta Chacaya (PC) within 10–50 m water-depth gradient. PR sediments were organic matter rich (21.1% of TOM at 50 m) and overlaid with low-oxygen waters (<0.06 ml O2/L bottom layer) compared with PC. In general, HMs like Al, Ni, Cd, As and Pb tended to increase in concentration with depth in PR, while the opposite pattern was observed in PC. In addition, PR presented a higher number of unique families (72) compared to PC (35). Among the top ten microbial families, Desulfobulbaceae (4.6% vs. 3.2%), Flavobacteriaceae (2.8% vs. 2.3%) and Anaerolineaceae (3.3% vs. 2.3%) dominated in PR, meanwhile Actinomarinales_Unclassified (8.1% vs. 4.2%) and Sandaracinaceae (4.4% vs. 2.0%) were more abundant in PC. Multivariate analyses confirmed that water depth-related variation was a good proxy for oxygen conditions and metal concentrations, explaining the structure of benthic microbial assemblages. Cd, Ni, As and Pb showed uniformly positive associations with communities that represented the keystone taxa in the co-occurrence network, including Anaerolineaceae, Thiotrichaceae, Desulfobulbaceae, Desulfarculaceae and Bacteroidales_unclassified communities. Collectively, these findings provide new insights for establishing the ecological interconnections of benthic microorganisms in response to metal contamination in a coastal upwelling environment.

Original languageEnglish
Article number117281
JournalEnvironmental Pollution
Volume286
DOIs
StatePublished - 1 Oct 2021

Bibliographical note

Funding Information:
We would like to thank Sue Ellen Vega for having performed for HMs analysis. As well as we are grateful to Maritza Fajardo and Luis Aguilar for their enthusiastic participation in sample collection. This work is part of the Ph.D. Thesis of Ana Zárate was funded by the Chilean National Commission for Scientific and Technological Research Scholarship for Doctoral Studies (CONICYT-PCHA/Doctorado Nacional/2015–21150407). We also thank the National Commission for Scientific and Technological Research ( FONDECYT 1181773 ; Center CeBiB FB 0001) of Cristina Dorador and to partial support by the Fondo Nacional de Desarrollo Científico Tecnológico (Chile) project number 1150042 granted to Aldo S. Pacheco. Finally, We gratefully to reviewers for their valuable comments and suggestions.

Funding Information:
We would like to thank Sue Ellen Vega for having performed for HMs analysis. As well as we are grateful to Maritza Fajardo and Luis Aguilar for their enthusiastic participation in sample collection. This work is part of the Ph.D. Thesis of Ana Z?rate was funded by the Chilean National Commission for Scientific and Technological Research Scholarship for Doctoral Studies (CONICYT-PCHA/Doctorado Nacional/2015?21150407). We also thank the National Commission for Scientific and Technological Research (FONDECYT 1181773; Center CeBiB FB 0001) of Cristina Dorador and to partial support by the Fondo Nacional de Desarrollo Cient?fico Tecnol?gico (Chile) project number 1150042 granted to Aldo S. Pacheco. Finally, We gratefully to reviewers for their valuable comments and suggestions.

Publisher Copyright:
© 2021 Elsevier Ltd

Keywords

  • Heavy metals
  • Marine sediment
  • Microbial network assemblages
  • Semi-enclosed bay

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