Churun Ain

Relationships between of Sea Urchins Abundance, Macroalgae and Coral Closure on the Cemara Kecil island

Sea urchins are one of the key species for coral reef communities because have the capability for controlling populations of microalgae. The existance of sea urchins in an waters ecosystem influenced by abiotic and biotic environmental factors such as intraspecific or intraspecific interactions. This study aims to determine the relationship between the abudance of Sea Urchins, Macroalga on massive coral, and coral cover on Cemara Kecil Island by PCA analysis. The study was conducted in May 2017 in Cemara Kecil Island. Method of research with Haphazard sampling technique. The result indicate that numbers of sea urchins found ranges from 78-130 ind/m2, an abudance of macroalgae found are Sargassum sp 1.36%, Caulerpa sp. 7.43% and Padina sp. 91.21%. The results of substrate cover are living coral 47,21%, dead coral 23.33%, othe fauna 2.85% and abiotic element 26.6%. Based on the results of PCA analysis that Sea Urchin abudance has a positive correlation with the closure of Coral Reef and Caulerpa sp. While the Padina sp. and Sargassum sp. have a positive correlation as well as abiotic factors, dead coral, and other fauna.