Contribution of Terrestrial Runoff to Coral Disease Prevalence on North Bali’s Massive Porites
Abstract: The widespread of
coral disease may threatened Bali`s marine tourism which is the main asset for
the nation prosperity. However, the disease prevalence is still unknown, in
particular inshore coral reefs near to tourist spot areas. Therefore, the
research aims to investigate the contribution of terrestrial runoff to coral
disease prevalence and to examine the relationships between disease prevalence
and environmental parameters (nitrate, phosphate, organic carbon and total
suspended solids (TSS)) within the population of massive Porites on shallow north
Bali reefs. Syndrome, diseases and healthy colonies of massive Porites coral
were counted and noted within a 2 x 10 m belt transect at 3 sampling sites. The
dominant disease observed was ulcerative white spots (UWS), while the syndromes
were pigmentation response and aggressive overgrowth by macroalgae. The highest
mean UWS prevalence was at site 3 which was the closest site to runoff
(prevalence = 91%).This disease only affected one colony at site 1 and 2,
respectively. Disease prevalence had strong relationship with TSS and nitrate,
yet it showed weak relationship with phosphate and organic carbon. These
results suggest that terrestrial runoff could contribute to the disease
prevalence by increasing the TSS, nutrients and organic carbon loading to the
inshore ecosystems. High level of organic carbon could severe the disease,
particularly when combined with elevated TSS and nutrient, by reducing the
coral`s immunity system.
Keywords: coral disease,
prevalence, terrestrial runoff, Porites, ulcerative white spot, environmental
parameter, North Bali
Author: I Gusti Bagus
Siladharma, Widiastuti Karim
Journal Code: jpperikanangg170049
