Marine & Environmental Sciences Faculty Proceedings, Presentations, Speeches, Lectures

Greater Diversity in Symbiont Types within Florida Dendrogyra cylindrus: Persistent Shift in Dominant Symbiont Sub-Types and Evidence of Cryptic Novel Clade

Event Name/Location

13th International Coral Reef Symposium, Honolulu, Hawaii, June 19-24, 2016

Presentation Date


Document Type

Conference Proceeding




Most scleractinian corals form stable symbioses with dinoflagellates,Symbiodinium spp, typically with a single dominant symbiont type. The Caribbean Pillar coral, Dendrogyra cylindrus, harbors ITS2-B1/cp23S-B184 symbiont as its dominant type. Following a mass hyper-thermal event in August and September 2014 along the Florida Reef Tract, the D. cylindrus population was severely bleached. Using high-throughput Illumina sequencing of the 23S cpDNA gene region, symbiont populations within D. cylindrus were characterized monthly during four months of recovery. Two operational taxonomic units (OTU0.03) representing B1 phylotypes accounted for > 80% of the relative abundance in symbiont populations prior to thermal bleaching. Shift in dominance of one OTU B1 subtype from <10% pre-bleaching to >50% post bleaching occurred at a site, which recovered more rapidly than sites that did not shift Symbiodinium composition. Evidence of cryptic Clade A symbionts (Symbiodinium necroappetens) in low abundance prior to bleaching (<0.1%) were found to temporarily increase in relative abundance to 3.5% during early recovery, suggesting an opportunistic growth with an unknown functional role during recovery. These findings indicate greater symbiont diversity within D. cylindrus than previously known and the ability to shift to potentially more favorable symbiont types. Previously undetected diversity within symbiont communities of a single coral host may impart ecological benefits, providing a measure of resilience to environmental stressors linked with climate change for this coral species.

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