Local confinement of disease-related microbiome facilitates recovery of gorgonian sea fans from necrotic-patch disease

Abstract

Microbiome disruptions triggering disease outbreaks are increasingly threatening corals worldwide. In the Tropical Eastern Pacific, a necrotic-patch disease affecting gorgonian corals (sea fans, Pacifigorgia spp.) has been observed in recent years. However, the composition of the microbiome and its disease-related disruptions remain unknown in these gorgonian corals. Therefore, we analysed 16S rRNA gene amplicons from tissues of healthy colonies (n = 19) and from symptomatic-asymptomatic tissues of diseased colonies (n = 19) of Pacifigorgia cairnsi (Gorgoniidae: Octocorallia) in order to test for disease-related changes in the bacterial microbiome. We found that potential endosymbionts (mostly Endozoicomonas spp.) dominate the core microbiome in healthy colonies. Moreover, healthy tissues differed in community composition and functional profile from those of the symptomatic tissues but did not show differences to asymptomatic tissues of the diseased colonies. A more diverse set of bacteria was observed in symptomatic tissues, together with the decline in abundance of the potential endosymbionts from the healthy core microbiome. Furthermore, according to a comparative taxonomy-based functional profiling, these symptomatic tissues were characterized by the increase in heterotrophic, ammonia oxidizer and dehalogenating bacteria and by the depletion of nitrite and sulphate reducers. Overall, our results suggest that the bacterial microbiome associated with the disease behaves opportunistically and is likely in a state of microbial dysbiosis. We also conclude that the confinement of the disease-related consortium to symptomatic tissues may facilitate colony recovery.

Microbiomes of Caribbean Octocorals Vary Over Time but Are Resistant to Environmental Change

“…Despite bacterial microbiome presence in both scleractinian and octocoral holobionts, knowledge about the relationships between octocorals and their bacterial microbiome is sparse. With next generation sequencing, the bacterial microbiomes of eight temperate and deep sea gorgonian species, all of whom do not host Symbiodiniaceae, were characterized (Vezzulli et al, 2013;van de Water et al, 2017van de Water et al, , 2018bGoldsmith et al, 2018;Quintanilla et al, 2018). In addition, the microbiomes of seven gorgonian species that host endosymbiotic Symbiodiniaceae, including five species from shallow water Caribbean reefs, were described (e.g., Sunagawa et al, 2010;Tracy et al, 2015;McCauley et al, 2016;Shirur et al, 2016).…”

Dynamic Interplay of ENSO Events and Local Hydrodynamic Parameters Drives Demography and Health Status of Gorgonian Sea Fan Populations on a Remote Tropical Eastern Pacific Island

“…Moreover, the fact that we did not find correlations between local/global environmental parameters and NPD prevalence suggests a random and occasional behavior of the disease in P. cairnsi. This assumption is also supported by the fact that NPD affecting P. cairnsi in Malpelo Island behaves opportunistically and is likely in a state of microbial dysbiosis (Quintanilla et al, 2018). Interestingly, while tissue breakage in shallow, wave-exposed waters is energetically costly and affects growth rates, it also facilitates recovery from NPD via physical loss of affected, peripheral tissues.…”

“…These gorgonian populations cope with cold waters and high levels of suspended matter during seasonal upwelling (from December to March), as well as anomalous increases in seawater temperature during sporadic El Niño-Southern Oscillation (ENSO) events (Glynn and Colgan, 1992;Zapata et al, 2010). Moreover, in recent years, P. cairnsi die-offs in Malpelo have been associated to disease outbreaks (Sánchez et al, 2011;Barrero-Canosa et al, 2013), namely the "necrotic-patch disease' (NPD) (Quintanilla et al, 2018).…”

Multiple impacts of microplastics can threaten marine habitat-forming species

“…To investigate the physical damage of the microplastic mixture on the coral tissues, samples (one branch from each tank including the control) were collected before the start of the experiment (t0), after 7 days and at the end of the experiment and prepared for SEM analyses according to standard protocols 82 with some modifications. Coral branches were stored in 0.7 µm prefiltered seawater with 4% buffered formalin.…”

“…Samples were stored at +4 °C. We dehydrated samples using different gradients of ethanol solutions (70–80%, 80–90%, 90–95%, 95–99% in 2 days) 82 . Then, samples were dried using HMDS (Hexamethyldisilazane, Aldrich 440191) 83 .…”