Microbial dysbiosis reflects disease resistance in diverse coral species

Abstract

Disease outbreaks have caused significant declines of keystone coral species. While forecasting disease outbreaks based on environmental factors has progressed, we still lack a comparative understanding of susceptibility among coral species that would help predict disease impacts on coral communities. The present study compared the phenotypic and microbial responses of seven Caribbean coral species with diverse life-history strategies after exposure to white plague disease. Disease incidence and lesion progression rates were evaluated over a seven-day exposure. Coral microbiomes were sampled after lesion appearance or at the end of the experiment if no disease signs appeared. A spectrum of disease susceptibility was observed among the coral species that corresponded to microbial dysbiosis. This dysbiosis promotes greater disease susceptiblity in coral perhaps through different tolerant thresholds for change in the microbiome. The different disease susceptibility can affect coral’s ecological function and ultimately shape reef ecosystems.

Reef Sediments Can Act As a Stony Coral Tissue Loss Disease Vector

“…The ASV5294 from the current study was most closely related to ASV29944 from Rosales et al (2020), with the sequences showing 99.24% nucleotide identity within the order Rhodobacterales (Table 3). Rhodobacterales have been found to be enriched in multiple coral diseases as well as SCTLD, including multiple white syndrome-like diseases, white band disease, and black band disease (Sunagawa et al, 2009;Miller and Richardson, 2011;Meyer et al, 2019;Gignoux-Wolfsohn et al, 2020;Rosales et al, 2020;MacKnight et al, 2021), demonstrating an opportunistic type of colonization and infection. Despite repeated analyses on a filtered dataset to remove origin/bottleneck effects on microbial communities, only one additional ASV (ASV3332) was found to be enriched in sediment samples following SCTLD inoculation, besides those already identified in analysis of the full dataset (Supplementary Table 2).…”

Characterization of the Microbiome of Corals with Stony Coral Tissue Loss Disease along Florida’s Coral Reef

“…In the epidemic zone, there were also significant differences in the species richness among tissue sample types, with DL tissues having a higher species richness compared to both DU and AH tissues in three species (C. natans, M. cavernosa, and S. siderea) and compared to the AH tissue of two species (O. faveolata and P. strigosa). This difference in alpha diversity may be a result of microbial dysbiosis, or an imbalance in the natural microbiome that can disrupt coral-microbe interactions and lead to disease [8,58]. The microbiomes of corals exposed to stressful environmental conditions (e.g., acidification, and increased temperature) often experience a shift in microbial community composition and, consequently, an increase in the species richness [8,59].…”

“…Microbial shifts may be attributed to a loss in beneficial bacteria; thus, freeing up niche space for putative pathogens to inhabit [13,60]. In a study conducted by MacKnight et al [58], disease-resistant corals exposed to white plague disease (WPD) had a higher dysbiosis threshold compared to corals that developed WPD lesions. The authors hypothesized that certain bacteria may be helping to prevent pathogens from colonizing disease-resistant corals; thus, also preventing dysbiosis and the onset of WPD.…”

Adaptive variation in homologue number within transcript families promotes expression divergence in reef‐building coral

“…However, C . natans is also considered to be susceptible to disease (Aeby et al, 2019; MacKnight et al, 2021; Sutherland et al, 2004) and demonstrates expansions in immune‐related transcript families. Thus, the relationship between an expanded immune transcript repertoire may not always lead to resistance to a particular disease in situ .…”

“…The loss of these once dominant species has led to the increased relative abundance of species in other genera such as Porites and Siderastrea (Green et al, 2008; McWilliam et al, 2020). Studies focusing on comparable aspects of species biology, such as growth rate, immune activity and Symbiodiniaceae communities, have sought to draw links between species differences and the heterogenous responses these species show during environmental stress (Baumann et al, 2018; Bove et al, 2019; MacKnight et al, 2021; Pinzón et al, 2014). However, the genetic component and interspecies differences in expression have not been investigated in a quantitative way.…”