Spatio-temporal coral disease dynamics in the Wakatobi Marine National Park, South-East Sulawesi, Indonesia

Abstract

In the present study we investigated inter-annual coral disease dynamics, in situ disease progression rates, and disease-associated coral tissue mortality in the Wakatobi Marine National Park (WMNP) situated in the coral triangle in South-East Sulawesi, Indonesia. In 2005, only 2 known syndromes were recorded within the sampling area transect surveys: white syndrome (WS; 0.42% prevalence) and growth anomalies (GA; 0.15% prevalence), whilst 4 diseases were recorded in 2007: WS (0.19%), Porites ulcerative white spot disease (PUWS; 0.08%), GA (0.05%) and black band disease (BBD; 0.02%). Total disease prevalence decreased from 0.57% in 2005 to 0.33% in 2007. In addition to prevalence surveys, in situ progression rates of 4 diseases were investigated in 2007: BBD on Pachyseris foliosa, P. rugosa and Diploastrea heliopora, WS on Acropora clathrata, and brown band (BrB) and skeletal eroding band (SEB) diseases on Acropora pulchra. BrB and WS had the highest progression rates, 1.2 ± 0.36 and 1.1 ± 0.07 cm d–1, respectively, indicating that diseases may have a significant impact on local Acropora populations. BBD had the lowest progression rate (0.39 ± 0.14 cm d–1). WS caused the most severe recorded total tissue mortality: 53923 cm2 over a period of 36 d. Sedimentation and coral cover were studied and a highly significant drop in coral cover was observed. This study provides the first documentation of spatio-temporal coral disease dynamics from Indonesia. Despite low total disease prevalence, progression rates comparable to the ones observed in the Caribbean and Australia indicate that diseases may threaten the reef framework in some locations and add to the degradation of coral reefs in a region already at high risk from anthropogenic impacts.