Impacts of environmental stress on resistance and resilience of algal-associated bacterial communities.

Kathryn Lee Morrissey,Anne Willems,Ljiljana Iveša,Sofie D'Hondt,Olivier De Clerck,Soria Delva

doi:10.1002/ece3.8184

Kathryn Lee Morrissey, Anne Willems + Show 4 more

Open Access

https://doi.org/10.1002/ece3.8184

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Abstract

Algal‐associated bacteria are fundamental to the ecological success of marine green macroalgae such as Caulerpa. The resistance and resilience of algal‐associated microbiota to environmental stress can promote algal health and genetic adaptation to changing environments. The composition of bacterial communities has been shown to be unique to algal morphological niches. Therefore, the level of response to various environmental perturbations may in fact be different for each niche‐specific community. Factorial in situ experiments were set up to investigate the effect of nutrient enrichment and temperature stress on the bacterial communities associated with Caulerpa cylindracea. Bacteria were characterized using the 16S rRNA gene, and the community compositions were compared between different parts of the algal thallus (endo‐, epi‐, and rhizomicrobiome). Resistance and resilience were calculated to further understand the changes of microbial composition in response to perturbations. The results of this study provide evidence that nutrient enrichment has a significant influence on the taxonomic and functional structure of the epimicrobiota, with a low community resistance index observed for both. Temperature and nutrient stress had a significant effect on the rhizomicrobiota taxonomic composition, exhibiting the lowest overall resistance to change. The functional performance of the rhizomicrobiota had low resilience to the combination of stressors, indicating potential additive effects. Interestingly, the endomicrobiota had the highest overall resistance, yet the lowest overall resilience to environmental stress. This further contributes to our understanding of algal microbiome dynamics in response to environmental changes.

Highlights

Eukaryotic organisms across all kingdoms of life are host to complex interactions with microbial partners, otherwise known as their microbiota (Relman, 2008)
We hypothesize that (a) bacterial community resistance and resilience to environmental perturbation are dependent on morphological niche association, and (b) bacterial community responses differ between types of stress and the combination of two stressors
This study documents the taxonomic and predicted functional changes in bacterial communities associated with the green alga Caulerpa cylindracea in response to in situ pulse disturbances of environmental conditions

Summary

| INTRODUCTION

Eukaryotic organisms across all kingdoms of life are host to complex interactions with microbial partners, otherwise known as their microbiota (Relman, 2008). In the field of algal microbiomes, studies have mainly focused on characterizing associated bacteria from natural habitats that differ in environmental parameters and not from in situ simulated experiments (Aires et al, 2016; Bengtsson et al, 2010; Burke et al, 2011; Campbell et al, 2015; Egan et al, 2013; Hollants, Leliaert, Verbruggen, Willems, et al, 2013; Mancuso et al, 2016). We performed in situ heatwave manipulations and nutrient enrichments within semiclosed mesocosm systems The aim of these investigations was to characterize the effect of pulse abiotic disturbance on the bacterial communities associated with individual morphological niches of the green algae Caulerpa cylindracea, as well as the surrounding environment. We hypothesize that (a) bacterial community resistance and resilience to environmental perturbation are dependent on morphological niche association, and (b) bacterial community responses differ between types of stress and the combination of two stressors

| MATERIALS AND METHODS

Findings

| DISCUSSION