Significant Changes in Microbial Communities Associated With Reef Corals in the Southern South China Sea During the 2015/2016 Global‐Scale Coral Bleaching Event

Abstract

Microbial communities play important roles as coral symbionts, but their changes among coral species in response to thermal bleaching events are not well understood. Therefore, we focused on the microbial communities associated with coral species in the southern South China Sea (SCS) during the 2015/2016 global‐scale coral bleaching event (GCBE). Samples of eight typical coral species were collected before and during the GCBE, and the microbial communities, potential gene functions, and zooxanthellae densities (ZDs) were analyzed. We found that ZDs significantly decreased among all coral species during the GCBE. Alpha diversities of the microbial communities also significantly decreased at different taxonomic levels among these coral species. Principal coordinates analysis revealed significant differences in beta diversity among coral specimens, which were divided into two groups before and during the GCBE. Microbial gene functional prediction showed that microbial community physiology significantly changed during the GCBE, with decreased coverage in metabolism, membrane transport, replication and repair, and increased coverage in cell motility and signal transduction. Moreover, the abundance of potential pathogens such as the genus Vibrio greatly increased (from ~0.28% to ~52.92%) during the GCBE, whereas the abundance of several beneficial microbes such as Endozoicomonas significantly decreased (from ~26.10% to ~0.91%), resulting in an obvious decline in the coral‐holobiont physiological functions. Thus, the GCBE greatly affected the health of coral species in the southern SCS, by reducing the biodiversity of associated microbial communities and increasing the abundance of potential pathogens.

Coastal Upwelling Under Anthropogenic Influence Drives the Community Change, Assembly Process, and Co‐Occurrence Pattern of Coral Associated Microorganisms

“…In particular, we revealed higher relative abundance of chemoheterotrophy and aerobic chemoheterotrophy metabolisms in corals collected from upwelling than that in non‐upwelling, which are categorized as broad metabolic or ecologically relevant functional groups (Rivett & Bell, 2018). In fact, similar to the current findings, corals under thermal stress during the 2015/2016 global‐scale coral bleaching event were generally suppressed in metabolism (Qin et al., 2020). The better metabolic activities of corals in upwelling may imply that the corals acclimatized to the local environment by regulating the coral microbiome composition, resulting in various metabolism‐related functions.…”

Microbiome of juvenile corals in the outer reef slope and lagoon of the South China Sea: insight into coral acclimatization to extreme thermal environments

“…ANOSIM was based on unweighted UniFrac distances, and bacteria predicted gene functions were analysed based on PICRUSt among coral species studied in the ORS and lagoon. Detailed descriptions of the analytical methods are reported by Qin and colleagues (2020). Significant differences in coral‐associated bacterial communities were tested by ANOSIM with 9999 permutation‐based Bray–Curtis dissimilarity matrix in R (vegan package; Oksanen et al ., 2015).…”

A review: Aeration efficiency of hydraulic structures in diffusing DO in water

“…Anthropogenic activities including the direct release of harsh chemicals into streams, ponds, and rivers have completely destroyed the territorial water ecology [ 3 , 14 , 74 , 29 ]. High nutrient levels, poor water transparency, and the development of disease-carrying bacteria and viruses are indicators that these contaminants are becoming more and more prevalent in the water bodies [ 47 , 48 , 50 ]. The presence poisonous and oxygen depriving cyanobacteria indicates advanced eutrophication, which poses a grave danger to drinking water sources and the environmental manageability of inland water biological systems [ 40 , 46 ].…”