Combined Culture and DNA Metabarcoding Analysis of Cyanobacterial Community Structure in Response to Coral Reef Health Status in the South China Sea

Abstract

Cyanobacteria occupy an extraordinarily diverse array of ecological niches in coral reefs because they play multifaceted roles, including primary carbon and nitrogen fixation, calcification, nutrient cycling, and oxygen production, as well as coral reef degradation through skeletal biocorrosion and polymicrobial diseases. In this study, cyanobacterial diversity in sediment, water, and coral tissues were explored in relation to coral health status (slightly, moderately, and severely damaged) of coral reefs at Weizhou Island, South China Sea. Microscopy of taxa morphological characteristics was combined with 16S rRNA gene metabarcoding. Fifteen and forty-three cyanobacterial genera were identified based on universal prokaryotic 16S rRNA gene primers and cyanobacteria-specific 16S rRNA gene primers metabarcoding, respectively, indicating a more sophisticated efficiency of the latter. In addition, three out of seven cyanobacterial strains that were isolated and identified based on morphology and phylogeny could not be detected using either molecular method. Therefore, culture-based combined cyanobacteria-specific 16S rRNA gene metabarcoding are highly recommended in future routine surveys. There was a clear distinction in cyanobacterial assemblage composition among locations with different coral health statuses, with degraded reefs exhibiting approximately a 1.25-fold increase in species compared to healthy habitats. In addition, the spreading of potentially toxic cyanobacteria, such as Nostoc and Lyngbya, in the degraded reef implies putative links to reef degradation. This study provides novel insights into the taxonomical diversity of cyanobacteria in tropical coral reefs. Metabarcoding is recommended as an effective tool for revealing cyanobacterial diversity patterns and thereby providing critical information for the effective management of coral reef ecosystems.

Convergent photophysiology and prokaryotic assemblage structure in epilithic cyanobacterial tufts and algal turf communities

“…Amplicon sequence variants belonging to the phylum Cyanobacteria were not well represented in this metabarcoding dataset (281 total unique ASVs; Cyanobacterial Tuft: 1.51% ± 0.27% SE; Turf Algae: 1.03% ± 0.13% SE TSS relative abundance). Similar low recovery of cyanobacterial taxa using universal bacterial 16S rRNA gene primer sets is well documented in the literature (e.g., recently by Kang et al, 2022), making the low cyanobacterial recovery in this particular universal amplicon dataset unsurprising.…”

Identification of quorum sensing-regulated Vibrio fortis as potential pathogenic bacteria for coral bleaching and the effects on the microbial shift

“…The coral-associated microorganisms play important roles to maintain the health of coral holobiont (Rosenberg et al, 2009;Kang et al, 2022), which assists the coral host to adapt to the environmental changes by a shift of the symbiotic microorganism community. However, the changes in environmental conditions might lead to the disorder of the microorganism community, including the dissociation of algal symbionts from the coral symbiotic microecosystem, which normally causes coral bleaching, or a shift in the bacterial community, which results in unbalanced nutrition metabolism, which causes coral disease, or the increasing richness of opportunistic pathogens, which causes bacterial infection (Mao-Jones et al, 2010).…”

Editorial: The response of microalgae and plankton to climate change and human activities

“…Rising ocean temperatures are causing shifts in the distribution of microalgae and plankton species, with poleward movements observed in various regions, indicating changes in oceanic ecosystems (Benedetti et al, 2021). Eutrophication, primarily driven by agricultural runoff and urban wastewater, triggers harmful algal blooms (Glibert, 2020;Kang et al, 2022). These blooms, upon decomposition, disrupt the food chain, leading to the demise of higher trophic level marine animals, and can even pose risks to human health (Liu et al, 2020).…”