Towed-Diver Observations in the Main Hawaiian Islands to Assess the Mass Coral Bleaching Event in November 2015

A team from the Pacific Islands Fisheries Science Center (PIFSC), Coral Reef Ecosystem Program (CREP) deployed on a two-week research cruise in November 2015 to evaluate the impacts of the 2015 mass coral bleaching event in the Main Hawaiian Islands via towed-diver surveys. Areas surveyed included south Oahu, west Maui, Lanaâi, and west Hawaii island. Over the course of 10 survey days, the team surveyed approximately 90 km of 15-m wide transects at depths ranging from 2 to 10 m. 

Data provided in this dataset include visual estimates recorded by towed divers of percentage of live coral that was pale and bleached, as well as presence/absence data of condition by generic composition.  Analysis of observer data reveals estimates of live coral affected by the event (pale or bleached) show a regional mean of 38.8% (+/- 1.96% CI95), with large variation in impact apparent between transects on the same island separated by as little as 13 km.

Additionally, instruments mounted on the towboards collected other in-situ data that are documented separately. A downward-facing DSLR camera with strobes collected photographic quadrat data by capturing an image of the benthos at 15-second intervals during the surveys. Oceanographic data was collected continuously throughout each survey with a suite of mounted sensors recording conductivity, temperature, depth, flourometry (chlorophyll-a), turbidity and dissolved oxygen. 

The towed-diver visual estimate data can be accessed online via the NOAA National Centers for Environmental Information (NCEI) Ocean Archive.

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Organization: National Oceanic and Atmospheric Administration, Department of Commerce