Community Research and Development Information Service - CORDIS


CAARL Report Summary

Project ID: 331450
Funded under: FP7-PEOPLE
Country: Spain

Final Report Summary - CAARL (Comparative Genomics and Environmental Diversity of Coral Associated Apicomplexa-Related Lineages)

Coral reefs are home to the greatest density of species in shallow marine waters, including diverse microbial communities. However, almost everything we know about reef microbial communities is confined to prokaryotes and viruses: next to nothing is known about the microbial eukaryotes (protists), with the exception of Symbiodinium. Symbiodinium (a dinoflagellate) forms an endosymbiotic interaction with coral that is critical to reef health: coral bleaching is the stress-related expulsion of Symbiodinium, and is a global threat to reef diversity. Beyond Symbiodinium, we know little about reef protist communities, how they interact with corals and other microbes, or the interplay between protists, environmental gradients, and coral health.

We have used 18S high-throughput sequencing to characterize the microeukaryotic community associated to corals other from Symbiodinium. Using an approach in which we excluded the metazoan signal from our datasets we have been able to identify two major protists groups associated to corals that are not the zooxanthella, the Apicomplexan Symbiont N and the Syndiniales. As well, we have been able to describe the diversity of protists belonging to the coral microbiome which signal was previously masked by the metazoan signal. Furthermore, we have studied the alga Ostreobium, that is known to be associated to corals but is still unclear if its role is beneficiary or pernicious to the animal. We have been able to retrieve its 18S rDNA sequence and its chloroplast genome. We have improved the phylogenetic placement of Ostreobium by using plastid genes and the 18S and we have characterized its biogeographical distribution using the 16S plastid gene.

Overall, we have expanded our knowledge on the coral associated protist communities beyond Symbiodinium, opening new venues for future research on coral ecology and physiology as well as protist evolution and ecology.

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Life Sciences
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