This study aims to determine the relationship between the density of sea urchins, cover macroalgae and live coral cover in the waters Pucung Island area . The method of research used survey method. Observations using purposive sampling method with 1×1 meter quadrant of the 124 sampling points in all four sampling area. Analysis of the relationship between the density sea urchins, cover macroalgae and live coral cover in the waters of Island regions Pucung done using bivariate correlation and simple regression.
The observation of the average density of sea urchins is 8,25 (ind/m2), the average cover of macroalgae 55,5 (%/ m2) and average live coral cover is 29,25 (%/m2). Results of bivariate correlation analysis of sea urchins and macroalgae value -0,94504, urchins and coral life is 0,9428 and macroalgae and corals live is -0,9495, Simple regression analysis that the required amount in the balance of the reef ecosystem that is 16 sea urchins feathers will stabilize 13% cover of macroalgae that live coral cover are in very good condition, namely 75% in 1m2.