Corallivory and the microbial debacle in two branching scleractinians

Abstract

The grazing activity by specific marine organisms represents a growing threat to the survival of many scleractinian species. For example, the recent proliferation of the corallivorous gastropod Drupella now constitutes a critical case in all South-East Asian waters. If the damaging effects caused by this marine snail on coral polyps are relatively well known, the indirect incidence of predation on coral microbial associates is still obscure and might also potentially impair coral health. In this study, we compared the main ecological traits of coral-associated bacterial and viral communities living in the mucus layer of Acropora formosa and Acropora millepora, of healthy and predated individuals (i.e., colonized by Drupella rugosa), in the Bay of Van Phong (Vietnam). Our results show a substantial impact of the gastropod on a variety of microbiological markers. Colonized corals harbored much more abundant and active epibiotic bacteria whose community composition shifted toward more pathogenic taxa (belonging to the Vibrionales, Clostridiales, Campylobacterales, and Alteromonadales orders), together with their specific phages. Viral epibionts were also greatly influenced by Drupella corallivory with spectacular modifications in their concentrations, life strategies, genotype richness, and diversity. Novel and abundant circular Rep-encoding ssDNA viruses (CRESS-DNA viruses) were detected and characterized in grazed corals and we propose that their occurrence may serve as indicator of the coral health status. Finally, our results reveal that corallivory can cause severe dysbiosis by altering virus-bacteria interactions in the mucus layer, and ultimately favoring the development of local opportunistic infections.

Parrotfish predation drives distinct microbial communities in reef-building corals

“…In addition, microbiomes of predated corals were characterized by moderate abundance (59.9% at T f ) of the putative beneficial symbiont Hahellaceae at 48 h when compared to Ti (83.9%). Lower abundance of Hahellaceae bacterial taxa is a pattern previously reported in stressed, mechanical injured, and predated corals [9,38,39,41].…”

Virus discovery in all three major lineages of terrestrial arthropods highlights the diversity of single-stranded DNA viruses associated with invertebrates

“…Most viral discovery studies focus on vertebrate hosts, primarily mammals, which limits our perspective of viral diversity and evolution. The work presented here expands on studies investigating CRESS DNA viruses in invertebrates, which have traditionally been undersampled ( Bettarel et al, 2018 ; Bistolas et al, 2017 ; Dayaram et al, 2013 ; Hewson et al, 2013b ; Kraberger et al, 2018 ; Rosario et al, 2012 , 2015a ; Wang et al, 2018 ). We report 44 CRESS DNA genomes recovered from arthropods representing all three major terrestrial arthropod lineages ( Giribet & Edgecombe, 2012 ).…”

Microbiome-aware Ecotoxicology: Relevance, Pitfalls and Challenges

“…Experimental investigations to date have focused mostly on bacteria. However, various studies have demonstrated the significance of Archaea and microbial Eukaryotes including fungi to hosts physiology (Hoffmann et al 2013;Richard and Sokol 2019), and the key role of phages in regulating bacterial populations (Mirzaei and Maurice 2017;Bettarel et al 2018). A comprehensive description of the microbiome functioning will emerge only when all components are accounted for (Rowan-Nash et al 2019).…”