Citizen Science Reveals the Prevalence
of the 2020 Mass Coral Bleaching in One Town

Wilfredo Y. Licuanan^1,2* and Princess Zyrlyn B. Mordeno¹

¹Br. Alfred Shields FSC Ocean Research Center
²Biology Department, College of Science
De La Salle University 1004 Manila, Philippines

*Corresponding author: wilfredo.licuanan@dlsu.edu.ph

ABSTRACT

Mass coral bleaching in recent decades is driven mainly by thermal stress and is of global concern. In mid-2020, the coral reefs of western Luzon, Philippines were exposed to unusually warm waters of up to 4.3 degree-heating weeks. Monitoring by a citizen science (CS) team based in Lian, Batangas showed 9–42% of the average hard coral cover (HCC) in each of six monitoring stations were bleached by July 2020. The HCC in the six stations in October 2020 was not significantly different from the sum of HCC and bleached coral cover in July, but the coral cover was mostly higher in 2019. These results suggest that loss of HCC happened earlier in the bleaching event of 2020, and the bleached corals in July had all recovered by October. The CS monitoring in Lian, Batangas demonstrates that local communities can measure the impact of disturbances like coral bleaching on reefs provided adequate methods and tools are available, and there is support from the government.