Abstract
The endemic Mediterranean zooxanthellate scleractinian reef-builder Cladocora caespitosa is among the organisms most affected by warming-related mass mortality events in the Mediterranean Sea. Corals are known to contain a diverse microbiota that plays a key role in their physiology and health. Here we report the first study that examines the microbiome and pathobiome associated with C. caespitosa in three different Mediterranean locations (i.e., Genova, Columbretes Islands, and Tabarca Island). The microbial communities associated with this species showed biogeographical differences, but shared a common core microbiome that probably plays a key role in the coral holobiont. The putatively pathogenic microbial assemblage (i.e., pathobiome) of C. caespitosa also seemed to depend on geographic location and the human footprint. In locations near the coast and with higher human influence, the pathobiome was entirely constituted by Vibrio species, including the well-known coral pathogens Vibrio coralliilyticus and V. mediterranei. However, in the Columbretes Islands, located off the coast and the most pristine of the analyzed locations, no changes among microbial communities associated to healthy and necrosed samples were detected. Hence, our results provide new insights into the microbiome of the temperate corals and its role in coral health status, highlighting its dependence on the local environmental conditions and the human footprint.
Highlights
The term microbiome describes the assemblage of microorganisms, active or inactive, associated with a habitat (Lederberg and McCray, 2001) and the core microbiome is comprised of the organisms that are common across the microbiomes from different habitats and likely play a key role within the habitat (Turnbaugh et al, 2007)
As an initial step in understanding microbial community variability in C. caespitosa and its potential association to the occurrence of coral tissue necrosis, we have identified the C. caespitosa core microbiome and pathobiome
The response or involvement of the microbial community in coral tissue necrosis seemed to be different in Columbretes than in Genova or Tabarca, where differences in microbial communities associated to coral health status were detected
Summary
Mass mortality events of benthic invertebrates from different phyla (sponges, cnidarians, molluscs, ascidians, and bryozoans) have increased in frequency in the last two decades in the temperate Mediterranean Sea, with catastrophic effects in benthic communities (Cerrano et al, 2000; Linares et al, 2005; Garrabou et al, 2009; Crisci et al, 2011; Kersting et al, 2013; Kružicand Popijac, 2015; Jiménez et al, 2016; Rubio-Portillo et al, 2016a). The occurrence of the recurrent mortality events in C. caespitosa has shown a significant association to positive thermal anomalies (Kersting et al, 2013) and the events were characterized by partial or total colony death due to polyp tissue necrosis (Rodolfo-Metalpa et al, 2005; Kersting et al, 2013) Extensive bioconstructions of this coral are very rare at the present time (Peirano et al, 1998) and a significant effort has been made to assess its response to different global change-related impacts, such as the increase of sea water temperature (Rodolfo-Metalpa et al, 2006a,b; Kersting et al, 2013). As an initial step in understanding microbial community variability in C. caespitosa and its potential association to the occurrence of coral tissue necrosis, we have identified the C. caespitosa core microbiome and pathobiome
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
