Porites ulcerative white spot disease: description, prevalence, and host range of a new coral disease affecting Indo-Pacific reefs.

The results of an investigation of a new coral disease affecting Indo-Pacific reefs are presented. Porites ulcerative white spot disease (PUWS) is characterized by discrete, bleached, round foci, 3 to 5 mm in diameter, that may either regress or progress to full tissue-thickness ulcerations that coalesce, occasionally resulting in colony mortality. Monitoring of 25 diseased and 5 healthy reference colonies for 17 mo revealed that advanced stages of the disease were characterized by lesion coalescence, partial colony death (i.e. portions of the colony still alive; n = 17) and total colony death (n = 2). Field transmission experiments revealed that 95% of healthy colonies developed lesions within 5 wk after continual exposure to diseased branches, while 60% of the reference colonies remained healthy. The host range of PUWS includes branching and massive Porites spp., and prevalence per species was positively correlated with species density. On 10 reefs surveyed in the Central Philippines, 22 +/- 7% (mean +/- SE) of poritid colonies were infected, and the disease was present on 80% of the surveyed reefs. Poritids are dominant Indo-Pacific reef builders; a disease targeting this genus could cause major shifts in community structure over time. This report contributes to the limited knowledge of PUWS impacts in this region.