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

Pocillopora Recovery at Devil's Crown, Galapagos Islands, Ecuador, Following Extirpation Associated with the 1982-83 El Nino-Southern Oscillation

Event Name/Location

11th International Coral Reef Symposium, Fort Lauderdale, Florida, July 7-11, 2008

Presentation Date

7-2008

Document Type

Conference Proceeding

Description

In 1982-83 a severe El Nino-Southern Oscillation (ENSO) event killed 95% of the scleracatinian corals in the Galapagos archipelago. Over 99% coral mortality occurred at the Devil's Crown study site located within the flooded (2-4m depth) center of a small (156 x 100m), emergent, dormant volcanic cone off the north coast of Floreana Island. Also at this site, a structural reef composed primarily of the branching coral Pocillopora spp. was lost from contrary wave action combined with primary and secondary biological disturbances associated with ENSO. For the subsequent 11 years Pocillopora was not observed there, however 5 colonies were seen in May, 1995. Since then the number and size of colonies were monitored approximately annually. Coral colony surface areas were determined following two methods: direct measure during snorkel surveys to determine maximum width and length (1995-2003), and digital photography to obtain 2-D images (2004 & 2007). These images were converted to projected surface area using the program CPCe. The numbers of Pocillopora colonies increased from 5 in 1995 to 154 in 2007, with total colony surface area increasing from 849cm2 to 37,772 cm2 (3.8m2) over the same period. Colonies initially appeared via sexual recruitment, probably from source populations located upcurrent, and now larger colonies are fragmenting and forming localized aggregations. This long term (25y) monitoring reveals slow initial recruitment from 1995 to 2002 followed by recent accelerated increases in Pocillopora colony number and surface area. This suggests that Pocillopora may once again attain population densities sufficient to form reef structures, an unusual prospect considering the widespread reports of coral loss worldwide.

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