Salinity and Time Can Alter Epibacterial Communities of an Invasive Seaweed

Abstract

The establishment of epibacterial communities is fundamental to seaweed health and fitness, in modulating ecological interactions and may also facilitate adaptation to new environments. Abiotic factors like salinity can determine bacterial abundance, growth and community composition. However, influence of salinity as a driver of epibacterial community composition (until species level) has not been investigated for seaweeds and especially under long time scales. We also do not know how abiotic stressors may influence the 'core' bacterial species of seaweeds. Following an initial (immediately after field collection) sampling of epibacterial community of an invasive red seaweed Agarophyton vermicullophylum, we conducted a long term mesocosm experiment for 5 months, to examine the influence of three different salinities (low, medium and high) at two different time points (3 months after start of experiment and 5 months, i.e., at the end of experiment) on the epibacterial community richness and composition of Agarophyton. Metagenomic sequencing showed that epibacterial communities changed significantly according to salinity and time points sampled. Epibacterial richness was significantly different between low and high salinities at both time points. Epibacterial richness also varied significantly between 3 months (after start of experiment) and 5 months (end of experiment) within low, medium and high salinity level. Irrespective of salinity levels and time points sampled 727 taxa consistently appeared in all Agarophyton samples hinting at the presence of core bacterial species on the surface of the alga. Our results indicate that both salinity and time can be major driving forces in structuring epibacterial communities of seaweeds with respect to richness and β-diversity. We highlight the necessity of conducting long term experiments allowing us to detect and understand epibacterial succession over time on seaweeds.

Decade‐scale stability and change in a marine bivalve microbiome

“…However, natural changes in SST observed across this study were markedly lower than those used in previous short‐term climate change experiments: 4–14°C (Li et al, 2018; Lokmer & Wegner, 2015) versus a range of ~1.6°C from 2008 to 2011. Similarly, differences in salinity have been shown to alter microbiome composition in experiments with multiple hosts including seaweeds (Saha et al, 2020) and corals (Röthig et al, 2016), although salinity variations in such experiments (8–19 practical salinity units (psu)) are typically much larger than the natural variations seen here (<0.1 psu). Decade‐scale microbiome differentiation has been previously shown in the human gut, although nearly 60% of bacterial phylotypes persisted over more than a decade (Faith et al, 2013).…”

Bacterial Communities Show Algal Host (Fucus spp.)/Zone Differentiation Across the Stress Gradient of the Intertidal Zone

“…Bacterial biodiversity often varies among different macroalgal hosts in a single location (Lachnit et al, 2009;Weigel and Pfister, 2019), within the same macroalgal host in different biogeographic regions (Roth-Schulze et al, 2018;Morelan et al, 2019), by tissue (Staufenberger et al, 2008;Quigley et al, 2018;Weigel and Pfister, 2019;Paix et al, 2020), or due to abiotic changes (Tujula et al, 2010;Michelou et al, 2013;Miranda et al, 2013;Longford et al, 2019;Qiu et al, 2019;Saha et al, 2020). Extensive studies of the biodiversity of bacteria on Baltic Sea Fucus vesiculosus, which is not usually exposed to air (Medvedev et al, 2016), found effects of different salinities (Stratil et al, 2014) and higher temperature (Stratil et al, 2013;Mensch et al, 2016).…”

Ecological and Industrial Implications of Dynamic Seaweed-Associated Microbiota Interactions

“…A recent study, that examined, through the use of metagenomic sequencing, the influence of various salinities (low, medium, and high) at different times (i.e., 3 and 5 months) on a sampling of epibacterial community of an invasive red seaweed Agarophyton vermiculophyllum (Ohmi) Gurgel, J.N. Norris et Fredericq, formerly Gracilaria vermiculophylla (Ohmi), revealed that the epibacterial richness varied both irrespectively of the salinity levels and time points [ 160 ]. Thus, it has been concluded by the authors that both salinity and time can be major driving forces in structuring epibacterial communities of seaweeds with respect to richness and diversity.…”