Biodiversity of Associated Megabenthic Invertebrate of Corall Reef Ecosystem of Petong Island Batam Indonesia

Global warming and climate changes were of the main environmental concern of marine scientist in the last three decade. As a biodiversity hotspot, marine coastal ecosystem faced an environmental threat because of increasing sea surface temperature (SST) and land base effluent, which in turn had an impact on the biodiversity of megabenthic faunal on coral reef community. The present paper studied the current condition of reef ecosystem as well as biodiversity of megabenthic community in Petong Island, a core zone of Batam Marine Management Area (BMMA), Riau Archipelago Province. Gradual changes of physical and chemical properties of seawater originated from coastal activities presumably has caused an effect on benthic faunal community structure. It revealed that benthic lifeform coral cover account for 30,53%, categorized into fairly good, whereas abiotic sand cover of 16,53%. The lifeform consists of Acropora (AC)1.73% and non-Acropora 28,80%. Death coral with algae (DCA) account for 40,40% and death corall (DC) 2,80%, Soft Corall (SC) 1,20%, fleshy seaweed (FS) 0,07%, other fauna (OT) 1,47%, and rubble (R) 7,00%. Apparently, only 4 of target species megabenthic fauna from eight, were eccounterred including; seaurchin (Diadema sp.), topshell ( Drupella sp.), giant clam ( Tridacna sp.), trochus ( Trochus sp.), with density of each megabenthic fauna calculated 5929, 1857, 71 and 71 ind/ha, respectively. It appeared that sea urchin were the highest density and followed by topshell ( Drupella sp). Sea urchin were noted as a bioindicator of reef ecosystem health. High density of sea urchin may indicate that reef in unhealthy state. The presence of Diadema Sitosum indicate that dead coral were present and it feed on algae growing in dead coral. High density of sea urchin may indicate that reef in unhealthy state