Ecosystem engineers drive differing microbial community composition in intertidal estuarine sediments

• Published in: PloS one 2021-02, Vol.16 (2), p.e0240952-e0240952
• Main Authors: Wyness, Adam J, Fortune, Irene, Blight, Andrew J, Browne, Patricia, Hartley, Morgan, Holden, Matthew, Paterson, David M
• Format: Article
• Language: English
• Subjects: Animal behavior; Bacteria; Biofilms; Biogeochemistry; Biological research; Biology; Biology and Life Sciences; Biology, Experimental; Blight; Coastal research; Community composition; Computer programs; Data analysis; Drafting software; Drying; Earth Sciences; Ecological research; Ecology; Ecology and Environmental Sciences; Ecosystem biology; Ecosystems; Editing; Engineering; Entomology; Environmental aspects; Estuaries; Estuarine sediments; Evolutionary biology; Funding; Macrofauna; Mesocosms; Methodology; Microbial colonies; Microorganisms; Mortality; Observations; Oceans; Physical Sciences; Research and Analysis Methods; Reviews; Salinity; Sediments; Software; Visualization; Wave forces; Wetting; Zoology
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0240952

Intertidal systems are complex and dynamic environments with many interacting factors influencing biochemical characteristics and microbial communities. One key factor are the actions of resident fauna, many of which are regarded as ecosystem engineers because of their bioturbation, bioirrigation and sediment stabilising activities. The purpose of this investigation was to elucidate the evolutionary implications of the ecosystem engineering process by identifying, if any, aspects that act as selection pressures upon microbial communities. A mesocosm study was performed using the well characterised intertidal ecosystem engineers Corophium volutator, Hediste diversicolor, and microphytobenthos, in addition to manual turbation of sediments to compare effects of bioturbation, bioirrigation and stabilisation. A range of sediment functions and biogeochemical gradients were measured in conjunction with 16S rRNA sequencing and diatom taxonomy, with downstream bacterial metagenome function prediction, to identify selection pressures that incited change to microbial community composition and function. Bacterial communities were predominantly Proteobacteria, with the relative abundance of Bacteroidetes, Alphaproteobacteria and Verrucomicrobia being partially displaced by Deltaproteobacteria, Acidobacteria and Chloroflexi as dissolved oxygen concentration and redox potential decreased. Bacterial community composition was driven strongly by biogeochemistry; surface communities were affected by a combination of sediment functions and overlying water turbidity, and subsurface communities by biogeochemical gradients driven by sediment reworking. Diatom communities were dominated by Nitzschia laevis and Achnanthes sp., and assemblage composition was influenced by overlying water turbidity (manual or biogenic) rather than direct infaunal influences such as grazing.