Bailey, H; D Swanson; B Vargas-Angel

Patterns of coral bleaching in American Samoa

2016

13th International Coral Reef Symposium. 19-24 June 2016

"The ongoing global coral bleaching event began in the North Pacific in the summer of 2014 and expanded to the South Pacific and Indian Oceans in 2015. The NOAA Coral Reef Watch outlook indicates it is likely to continue well into 2016. An ecosystem scale assessment of coral populations in American Samoa from February to March 2015 provides crucial information about the distribution and abundance of corals and the prevalence of bleaching at multiple spatial scales to affected genera and species. A two-stage stratified random sampling design was employed to survey 188 sites across 5 islands/atolls: Ofu-Olosega, Rose, Swains, Ta'u, and Tutuila. The stratification scheme incorporated island sectors, three reef zones (fore reef, back reef, and lagoon), and three depth categories (0-6 m, >6-18 m, and >18-30 m), where present. Coral abundance, size, partial mortality, condition (e.g. bleaching) were surveyed within two 10-m2 belt transects per site. Population prevalence of bleaching for all scleractinian corals combined was 5.47% (SE 0.61%), ranging from 66.04% to 0% among genera, and from 66.67% to 0% among selected species. The most affected genera include Isopora, Montastraea, Leptoseris, Fungia, Pavona, Pocillopora, and Porites. Bleaching prevalence varied across islands/atolls, strata, genera, and species. These results provide a quantitative assessment of bleaching patterns across habitat space, genera, and species during the survey period. In addition, the spatial pattern of bleaching identifies potentially vulnerable and resilient reefs in American Samoa."