Search Results (2)

Coral reefs, essential yet increasingly threatened marine ecosystems, rely on coral–microbiome symbioses for resilience against environmental stressors. This study investigates host-specific influences on bacterial communities in four Pocillopora species (Pocillopora eydouxi, Pocillopora meandrina, Pocillopora verrucosa, and Pocillopora woodjonesi) from the South China Sea. Using Illumina-based 16S rRNA gene sequencing, we analyzed microbiome structures, identified core taxa, and predicted metabolic functions. Results revealed that bacterial composition differed significantly among coral hosts, despite their shared habitat. P. eydouxi exhibited the highest bacterial richness and Shannon index, contrasting with minimal values in P. woodjonesi. A conserved core microbiome of 32 ASVs (1.1% of total ASVs), dominated by Gammaproteobacteria, was shared across all coral species. Host-specific enrichment of probiotic bacteria (Psychrobacter in P. eydouxi and Exiguobacterium in P. meandrina) and pathogenic taxa (e.g., Acinetobacter) was also observed. Functional prediction indicated conserved metabolic pathways across species, particularly amino acid and carbohydrate metabolism. These findings highlight host phylogeny as one of the primary determinants of microbiome assembly, providing critical insights into coral conservation strategies. Full article

Large eddy simulations were performed to characterize the flow and mass transport mechanisms in the interior of two Pocillopora coral colonies with different geometries, one with a relatively loosely branched morphology (P. eydouxi), and the other with a relatively densely branched structure (P. meandrina). Detailed velocity vector and streamline fields were obtained inside both corals for the same unidirectional oncoming flow, and significant differences were found between their flow profiles and mass transport mechanisms. For the densely branched P. meandrina colony, a significant number of vortices were shed from individual branches, which passively stirred the water column and enhanced the mass transport rate inside the colony. In contrast, vortices were mostly absent within the more loosely branched P. eydouxi colony. To further understand the impact of the branch density on internal mass transport processes, the non-dimensional Stanton number for mass transfer, St, was calculated based on the local flow time scale and compared between the colonies. The results showed up to a $219\%$ increase in St when the mean vortex diameter was used to calculate St, compared to calculations based on the mean branch diameter. Turbulent flow statistics, including the fluctuating velocity components, the mean Reynolds stress, and the variance of the velocity components were calculated and compared along the height of the flow domain. The comparison of turbulent flow statistics showed similar Reynolds stress profiles for both corals, but higher velocity variations, in the interior of the densely branched coral, P. meandrina. Full article