Abstract
In this study, 16S high-throughput and metagenomic sequencing analyses were employed to explore the changes in microbial community and function with the succession of mangroves (Sonneratia alba, Rhizophora apiculata, and Bruguiera parviflora) along the Merbok river estuary in Malaysia. The sediments of the three mangroves harbored their own unique dominant microbial taxa, whereas R. apiculata exhibited the highest microbial diversity. In general, Gammaproteobacteria, Actinobacteria, Alphaproteobacteria, Deltaproteobacteria, and Anaerolineae were the dominant microbial classes, but their abundances varied significantly among the three mangroves. Principal coordinates and redundancy analyses revealed that the specificity of the microbial community was highly correlated with mangrove populations and environmental factors. The results further showed that R. apiculata exhibited the highest carbon-related metabolism, coinciding with the highest organic carbon and microbial diversity. In addition, specific microbial taxa, such as Desulfobacterales and Rhizobiales, contributed the highest functional activities related to carbon metabolism, prokaryote carbon fixation, and methane metabolism. The present results provide a comprehensive understanding of the adaptations and functions of microbes in relation to environmental transition and mangrove succession in intertidal regions. High microbial diversity and carbon metabolism in R. apiculata might in turn facilitate and maintain the formation of climax mangroves in the middle region of the Merbok river estuary.
Highlights
Mangroves represent one of the most productive ecosystems in tropical and subtropical estuaries and shorelines
The highest total organic carbon (TOC) and total nitrogen (TN) levels were detected in the sediments of R. apiculata among the three mangroves studied (p < 0.05)
Desulfobacterales consistently had the highest contributions to carbon-related metabolism in the sediments associated with R. apiculata
Summary
Mangroves represent one of the most productive ecosystems in tropical and subtropical estuaries and shorelines They possess biological resources and play important roles in carbon fixation, erosion mitigation, and water purification (Giri et al, 2011; Brander et al, 2012). They often occur in marine-terrestrial ecotones with obvious geographical and hydrological heterogeneities, leading to interesting sequential species zonation along continuous gradients. The potential roles of microbes and their functions in mangrove ecosystems are still poorly understood, changes in vegetation during mangrove succession and how mangrove plants adapt to intertidal environmental adversities have been well studied (Wang et al, 2019; Cheng et al, 2020). Mangrove coverage regulates the structure and composition of microbial community by altering redox conditions and organic carbon levels in the sediments (Holguin et al, 2001)
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