A coral of a different color: Genetic insights to the diversity and distribution of gorgonian octocorals in the US Gulf of Mexico

OneNOAA Science Seminar Series 

Speaker: Peter Etnoyer – NOAA National Centers for Coastal Ocean Science, Deep Coral Ecology Lab

Sponsor: NOAA Deep Sea Coral Research and Technology Program

Point of Contact: heather.coleman@noaa.gov (301-427-8650)

Register for the webinar: https://attendee.gotowebinar.com/register/4201985300294108429.

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Abstract: Genetic analyses can provide critical information to assist restoration activities in the wake of environmental assaults, like the Deepwater Horizon (DWH) oil spill in the northern Gulf of Mexico (GoMx). The damage assessment for the DWH spill showed that several species of gorgonian octocorals on rocky reefs in the mesophotic zone (50-150 m) had significantly more injury post-spill compared to pre-spill conditions, but genetic diversity was unknown at the time. To meet the goals of restoration activities, this study set out to evaluate the mtDNA mutS and CO1+ igr gene regions of two injured taxa, from across the GoMx. DNA sequences were cross-referenced with museum specimens using BLAST. Results from the mtDNA mutS gene in samples of Swiftia exserta (n = 278) revealed three haplotypes in S. exserta, but no significant differences among phenotypic color morphs. Only one haplotype was found among presumptive Hypnogorgia pendula (n = 314). Homology searches for both species revealed inconsistencies with online data bases as presumptive Hypnogorgia samples exhibited high homology with Muricea pendula. Similarly, the S. exserta sequences failed to match other S. exserta sequences in GenBank, but they matched museum specimens. Phylogenetic analyses conducted using a subsample of octocoral mutS sequences in Genbank in conjunction with our data, revealed evidence of extreme divergence within the Swiftia. This is problematic as S. exserta is the type species for this genus. Our results indicate that the genera Hypnogorgia, Muricea, and Swiftia will require additional taxonomic analyses and possibly a systematic revision. To build upon these findings, sclerite morphology will be closely examined using scanning electron microscopy, and the nuclear marker 28S will be used to verify these findings. Other genera of gorgonian octocorals were injured by the spill (Thesea, Placogorgia, Paramuricea), and these may also benefit from inclusion into a larger molecular analysis.

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(Peter Etnoyer, NOAA National Centers for Coastal Ocean Science)