Conclusion:
Bioerosion rate is an important factor controlling coral community structure and calcium carbonate budget of coral reefs.
The present study aimed to estimate bioerosion rates caused by D. setosum in coral communities at Ko Ngam Yai, Chumphon Province.
The average of population density of D. setosum was 15.1 individuals/m2.
The mean bioerosion rate was calculated as 1.70 g CaCO3/individuals/day or 9.38 Kg CaCO3/m2/year.
The bioerosion rates were positively correlated with the sea urchin sizes.
This study indicated that the bioerosion rates at Ko Ngam Yai were higher than those in the Inner Gulf of Thailand.