A study of species diversity and distribution of sesea urchin at Bidong Island

Abstract

Four species of sea urchins were identified during sampling sessions. They were Diadema setosum, Diadema savignyi, Echinothrix calamaris, and Echinometra mathaei. The highest mean abundance of sea urchin species was Echinothrix calamaris (5.56±4.57 ind. 500m-2 ), followed by Diadema setosum (2.53±1.98 ind. 500m-2), Echinometra mathaei (0.49±0.47 ind. 500m-2), and Diadema savignyi (0.46±0.45 ind. 500m-2) respectively. ANO VA test showed that the distribution of sea urchin was affected by time and depth (P<0.001 ). Highest mean abundance of sea urchin individuals were observed at slope (3.72±3.97 ind. 500m-2), followed by middle (2.80±3.14 ind. 500m-2), and intertidal (0.28±0.3 ind. 500m-2 ) respectively. Based on Post Hoc analysis, there were significant difference (P<0.001) between three different level of depths towards the abundance of sea urchin. However, the abundance of sea urchin species was significant (P<0.001) for 9 p.m only, compared to the other periods. The most abundant species of sea urchin observed at Bidong Island was E. calamaris with 62% from total individuals of sea urchins observed during the sampling period. There were significant differences (P<0.001) between the effects of the time and depth on the distribution of the E. calamaris. Based on Post Hoc analysis, significant differences (P<O.O 1) were observed at three different level of depths towards the abundance of sea urchin. The abundance of E. calamaris also showed significant difference (P<0.00 I) between 9 p.m compared to the other hours. The distribution of D. setosum, D. savignyi and E. mathaei were only affected by depth (P<0.05) and not affected by the different ranges of time (P>0.05). Based on Post Hoc analysis, D. setosum showed significant difference (P<O.O 1) between three different level of depths while the abundance of D. savignyi was significant (P<0.05) between intertidal and slope. The distribution of E. mathaei showed the significant difference between intertidal and middle (P<0.01).