The coral assemblages of the north coast of Ishigaki were not overly affected by coral bleaching in 2016 that devastated many reefs in the Yaeyama Islands. The last major disturbance on the north coast of Ishigaki was a crown of thorns outbreak about 12 years ago, according to Dr. Go Suzuki who has been working on these reefs for over 20 years.
However, this year’s high sea-surface temperature, doldrum conditions and a lack of typhoons have resulted in widespread severe coral bleaching that started in early August 2022. It is an extraordinary sight. Vibrant blues, pinks and yellows, catch your eye among the bright white of the more typically bleached corals. These colours are the pigments of the coral host visible now that the symbionts, with their golden-brown pigments, have been expelled. A few weeks into this event, many colonies are already dead, covered with the brown of filamentous algae that grows on the exposed coral skeleton once the tissue has died. Most colonies are completely bleached, and with no sign of sea-surface temperatures cooling, most of these colonies will die. Living coral cover is likely to be less than 10% by the end of the year and many of the fish will also die once their habitat has gone. In a year, the reef will potentially be a silent still graveyard.
Seeing dead coral has never really affected me, I have been counting dead corals all over the world since half-way through my PhD, however being in Japan the event inspired me to write a haiku;
Andrew Baird, 2022
Vibrant blues and pinks
Among the bright ghostly white
The colours of death
Keith, S.A., Baird, A.H., Hobbs, JP.A. et al. Synchronous behavioural shifts in reef fishes linked to mass coral bleaching. Nature Clim Change 8, 986–991 (2018). https://doi.org/10.1038/s41558-018-0314-7
Semmler, R. F., Sanders, N. J., CaraDonna, P. J., Baird, A. H., Jing, X., Robinson, J. P. W., Graham, N. A. J., & Keith, S. A. (2022). Reef fishes weaken dietary preferences after coral mortality, altering resource overlap. Journal of Animal Ecology, 00, 1– 10. https://doi.org/10.1111/1365-2656.13796