Sensitivity
Field work to estimate coral ecological sensitivity were based on
coordinated surveys of coral bleaching during the 2016 El Niño and
global thermal anomaly event. All were undertaken after the post-peak
summer SSTs when bleaching was greatest (McClanahan et al. 2001). We
sampled the 226 sites in 12 countries between during summer months
between March and September 2016. We used a roving observer methodology
where an observer evaluates the frequency and severity of bleaching for
individual coral colonies in a series of haphazardly replicated quadrats
(~1.5 m2 x ~15
replicates, across an area of ~1000
m2). In some surveys, we photographed quadrats and
subsequently identified colonies to taxa and scored them for bleaching.
Within each quadrat, we identified hard coral colonies >5
cm to genus (Veron 2000), and scored each colony for bleaching severity
using the following categories: c 0 – normal; c 1 – pale;c 2 – 0-20% bleached; c 3 – 21-50% bleached; c 4
– 51-80% bleached, c 5 – 81-100% bleached; c 6 –
recently dead. These observations were used to estimate the average
percent of bleaching coral colonies and a weighted measure of bleaching
(McClanahan et al. 2007). We also recorded the site’s depth, habitat
type, and management. We also estimated hard coral cover in each quadrat
to the nearest 5% and the summarized the number of observed colonies,
coral taxa richness, and relative abundance for each site. Three sites
were missing one of more of the variables leading to slightly lower
sample sizes in some analyses.