Dataset: Estimates of bleaching mortality and colony size for Pocillopora spp. corals at Moorea in 2019

Photoquadrats (0.7 × 0.7m) were recorded at 10 m depth on the fore reef at six sites (24 quadrats from each of six sites covering the north, east, and west shore). Photoquadrats used to estimate bleaching mortality were collected along a transect that was immediately adjacent (~2m) to the MCR LTER transects at site 1 and 2. Bleaching mortality was measured by following the fate of individual Pocillopora spp. colonies in photoquadrats (marked with 12 inch stainless steel threaded rods) taken in February 2019, before the bleaching event, and again in August 2019, approximately four months after the peak of the bleaching event. Because we sampled the same photoquadrat in February and August, the status and fate of 1186 individual colonies could be tracked over time.

Colony size was quantified as the diameter (in centimeters) along the longest axis of the coral in planar view from the photoquadrat images. The size of a colony was not recorded if the colony was only partially in the frame and the longest axis could not be identified. As a result, size was measured for 641 out of 1023 (62%) colonies assigned to a bleaching category in May 2019, and 1125 out of 1186 (95%) of colonies observed in February 2019 and categorized as alive or dead in August 2019. Size was estimated using ImageJ software. Each photograph included a reference scale with which each image was individually size-calibrated. The smallest colony size detectable in the images was ~ 2 cm.