Mapping of Nitrate, Phospat and Zooxanthelae with Abundance of Sea Urchins on Massive Coral Reef in Karimunjawa Island

Abstract

Coral reefs have high organic productivity because coral reefs can withstand nutrients and accommodate all external inputs. Many factors affect the life of corals, which is nitrate, phosphate and zooxanthellae. The purpose of this study are to know mapping of the content and the relationship between of nitrate, phosphate, zooxanthellae and abundance of sea urchins on massive coral reefs in Karimunjawa Islands. This research was conducted in May-June 2017 in three stations are Karimunjawa, Menjangan Kecil and Cemara Kecil Island. The method used in this research is survey method with quantitative approach. Results of mapping of nitrate contents on massive corals on all three islands showed the highest nitrate content on Cemara Kecil Island and lowest on Karimunjawa island, with a range of values 5.078-212.853 mg/kg. In mapping the distribution of phosphate content in the three islands showed the highest phosphate content in Menjangan Kecil island and the lowest on Karimunjawa island, with a range of values from 6.78-19.35 mg/kg. Zooxanthelae map shows that the highest and lowest distribution of zooxanthela content on Karimunjawa island, with a range of values 2.84-8.88 cell/cm2. The sea urchins found in Karimunjawa Islands during the study were Diadema setosum and Echinothrix calamaris with a range of values 5-147. Based on multiple regression analysis showed that the relationship between nitrate, phosphate and zooxanthela with abundance of sea urchins showed a strong correlation result with correlation value (r) is 0.64. These results can be an indicator of coastal environmental health, especially coral reef ecosystems.