Authors | Jessica Breavington, Larissa Frühe, Chuancheng Fu, Alexandra Steckbauer, Shannon Klein, Christopher Hempel, and Carlos M. Duarte
Mangroves are highly effective carbon sinks and an important nature-based solution for mitigating climate change. However, Red Sea mangroves encounter challenging growth conditions due to their arid and nutrient-limited environment, resulting in lower primary productivity and soil carbon storage. Mangrove carbon budgets often overlook the contribution of microphytobenthos (MPB), representing a significant knowledge gap, particularly in the Red Sea. Therefore, the aim of this paper is to resolve composition of the microphytobenthos, their influence on greenhouse gas (GHG) fluxes, and soil carbon storage in mangrove ecosystems. From December 2021 to December 2022, monthly soil core samples were collected from a monospecific stand of Avicennia marina mangroves in the central Eastern Red Sea to conduct stable isotope analysis, eDNA microbial community assessment of MPB, and oxygen micro-profiles. Isotope analysis revealed that 85% of the soil carbon originated from MPB which demonstrated high photosynthetic productivity with clear peaks in microsensor profiling up-to 5.5 μmol O2 L s-1. Metabarcoding revealed Bacteroidota, Planctomycetota, and Proteobacteria were the predominant bacterial phyla. Alveolata and Stramenopiles were the dominant eukaryote families. Significant correlations were observed between microbial community composition and environmental variables, particularly salinity, temperature, and water volume. Microbial families were also correlated to soil GHG flux. Our study reveals that MPB is an important contributor to primary production and carbon storage within mangrove ecosystems. Furthermore, it is likely to reduce GHG flux through redox reactions and microbial metabolic processes. Future blue carbon studies in mangrove ecosystems should account for the presence and influence of microphytobenthos, due to its important impact on carbon budgets and mangrove ecosystem functioning.
Raw sequencing data can be accessed in the Sequence Read Archive (SRA) of NCBI under PRJNA993563. All code used to analyse and visualise data is stored in this GitHub repository.
Cutadapt&DADA2 for initial raw sequence data processing. PostDADA2_cleaning for data wrangling using phyloseq and decontam.
Project lead by Jessica Breavington - jessicabreavington@gmail.com . All repositories created and curated by [@lexscience].