Volume 49 Number 3

Herbivory influences coral-algal abundance and dynamics in different degrees of coral bleaching on a tropical subtidal reef community

Jatdilok Titioatchasai^a, Anchana Prathep^b, Jaruwan Mayakun^a,*

 
ABSTRACT:     Effect of herbivory on coral-algal community dynamics was experimentally investigated at the tropical subtidal reef crest using cages (uncaged and fully caged treatments) in different degrees of coral bleaching (healthy, bleached, and severely bleached). Cover, recruitment, and succession of coral and algae were monitored. In this study, twenty-three algal species were encountered, comprising three dominant groups: red turf algae, Padina sp., and Lobophora variegata. Red turf algae were dominant and persisted in bleached and severely bleached plots for a year. The results showed that herbivory had significant effects on the cover of algae and might contribute to differences in algal composition and abundance. There was significant difference in percent cover of Padina between caged and uncaged plots. The foliose form of Padina was dominant inside the cages while the Vaughaniella stage of Padina developed high percent covers on uncaged patches. It might be because Padina inside the cages had less grazing pressure from territorial damselfishes and other herbivorous fishes than thalli outside the cages. Therefore, the foliose form of Padina had greater cover in full cages than open cages. As expected, the percent cover of coral in the caged plots was lower than in uncaged plots. Coral juveniles settled in the severely bleached plots within one month and then disappeared. From this study, herbivory likely plays important roles in coral-algal abundance; however, the impact of herbivory varies according to degrees of coral bleaching that might also directly or indirectly influence coral-algal community dynamics and coral recovery

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* Corresponding author, E-mail: jaruwan.may@psu.ac.th

Received 3 Jun 2024, Accepted 22 Oct 2024