Water Column Microbial Communities Vary along Salinity Gradients in the Florida Coastal Everglades Wetlands

Peeter Laas; Kelly Ugarelli; Rafael Travieso; Sandro Stumpf; Evelyn E Gaiser; John S Kominoski; Ulrich Stingl

doi:10.3390/microorganisms10020215

Water Column Microbial Communities Vary along Salinity Gradients in the Florida Coastal Everglades Wetlands

Microorganisms. 2022 Jan 20;10(2):215. doi: 10.3390/microorganisms10020215.

Authors

Peeter Laas^{1

2

3}, Kelly Ugarelli¹, Rafael Travieso⁴, Sandro Stumpf⁴, Evelyn E Gaiser^{4

5}, John S Kominoski^{4

5}, Ulrich Stingl¹

Affiliations

¹ Fort Lauderdale Research and Education Center, Department of Microbiology & Cell Science, Institute of Food and Agricultural Sciences, University of Florida, Davie, FL 32611, USA.
² Department of Marine Systems, School of Science, Tallinn University of Technology, 12618 Tallinn, Estonia.
³ Institute of Technology, Faculty of Science and Technology, University of Tartu, 50411 Tartu, Estonia.
⁴ Institute of Environment, Florida International University, Miami, FL 33199, USA.
⁵ Department of Biological Sciences, Florida International University, Miami, FL 33199, USA.

Abstract

Planktonic microbial communities mediate many vital biogeochemical processes in wetland ecosystems, yet compared to other aquatic ecosystems, like oceans, lakes, rivers or estuaries, they remain relatively underexplored. Our study site, the Florida Everglades (USA)-a vast iconic wetland consisting of a slow-moving system of shallow rivers connecting freshwater marshes with coastal mangrove forests and seagrass meadows-is a highly threatened model ecosystem for studying salinity and nutrient gradients, as well as the effects of sea level rise and saltwater intrusion. This study provides the first high-resolution phylogenetic profiles of planktonic bacterial and eukaryotic microbial communities (using 16S and 18S rRNA gene amplicons) together with nutrient concentrations and environmental parameters at 14 sites along two transects covering two distinctly different drainages: the peat-based Shark River Slough (SRS) and marl-based Taylor Slough/Panhandle (TS/Ph). Both bacterial as well as eukaryotic community structures varied significantly along the salinity gradient. Although freshwater communities were relatively similar in both transects, bacterioplankton community composition at the ecotone (where freshwater and marine water mix) differed significantly. The most abundant taxa in the freshwater marshes include heterotrophic Polynucleobacter sp. and potentially phagotrophic cryptomonads of the genus Chilomonas, both of which could be key players in the transfer of detritus-based biomass to higher trophic levels.

Keywords: 16S rRNA amplicon sequencing; 18S rRNA amplicon sequencing; Florida Everglades; bacterioplankton; coastal microbiology; eukaryotic microbial communities.