Metals Alter Membership but Not Diversity of a Headwater Stream Microbiome

Brian A Wolff; William H Clements; Ed K Hall

doi:10.1128/AEM.02635-20

Metals Alter Membership but Not Diversity of a Headwater Stream Microbiome

Appl Environ Microbiol. 2021 Mar 11;87(7):e02635-20. doi: 10.1128/AEM.02635-20. Print 2021 Mar 11.

Authors

Brian A Wolff^{1

2}, William H Clements^{3

2}, Ed K Hall^{3

4

5}

Affiliations

¹ Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA wolffba@gmail.com.
² Department of Fish, Wildlife and Conservation Biology, Colorado State University, Fort Collins, Colorado, USA.
³ Graduate Degree Program in Ecology, Colorado State University, Fort Collins, Colorado, USA.
⁴ Department of Ecosystem Science and Sustainability, Colorado State University, Fort Collins, Colorado, USA.
⁵ Natural Resource Ecology Laboratory, Colorado State University, Fort Collins, Colorado, USA.

Abstract

Metal contamination from mining or natural weathering is a common feature of surface waters in the American west. Advances in microbial analyses have created the potential for routine sampling of aquatic microbiomes as a tool to assess the quality of stream habitat. We sought to determine if microbiome diversity and membership were affected by metal contamination and identify candidate microbial taxa to be used to indicate metal stress in stream ecosystems. We evaluated microbiome membership from sediments at multiple sites within the principal drainage of an EPA superfund site near the headwaters of the Upper Arkansas River, Leadville, CO. From each sample, we extracted DNA and sequenced the 16S rRNA gene amplicon on the Illumina MiSeq platform. We used the remaining sediments to simultaneously evaluate environmental metal concentrations. We also conducted an artificial stream mesocosm experiment using sediments collected from two of the observational study sites. The mesocosm experiment had a two-by-two factorial design: (i) location (upstream or downstream of contaminating tributary), and (ii) treatment (metal exposure or control). We found no difference in diversity between upstream and downstream sites in the field. Similarly, diversity changed very little following experimental metal exposure. However, microbiome membership differed between upstream and downstream locations and experimental metal exposure changed microbiome membership in a manner that depended on origin of the sediments used in each mesocosm.IMPORTANCE Our results suggest that microbiomes can be reliable indicators of ecosystem metal stress even when surface water chemistry and other metrics used to assess ecosystem health do not indicate ecosystem stress. Results presented in this study, in combination with previously published work on this same ecosystem, are consistent with the idea that a microbial response to metals at the base of the food web may be affecting primary consumers. If effects of metals are mediated through shifts in the microbiome, then microbial metrics, as presented here, may aid in the assessment of stream ecosystem health, which currently does not include assessments of the microbiome.

Keywords: 16S; bioassessment; mesocosms; metals; stream.

Publication types

Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

Bacteria / isolation & purification*
Colorado
Metals / adverse effects*
Microbiota / drug effects*
RNA, Bacterial / analysis
RNA, Ribosomal, 16S / analysis
Rivers / microbiology*
Water Pollutants, Chemical / adverse effects*

Substances

Metals
RNA, Bacterial
RNA, Ribosomal, 16S
Water Pollutants, Chemical