Study Of Coral Bleaching to the State of Coral Reef and Reef Fish in Weh Island, Sabang

Abstract

Sea surface temperature (SST) in Aceh waters had increased 4 oC which reach 33oC. This was the highest temperature recorded compared to the normal averages of 28-30 oC. The rise of SST had led to the death of coral reef. The peak of coral bleaching or bleaching index (BI) occurred on May 2010 which was 45.84 %. Meanwhile, it decreased on July 2010 and February 2011 which were (21,44 and 0,36%), respectively. The genera of Acropora and Pocillopora had a severe impact to the rise of SST which obviously led to the death. Both genera experienced 95% and 80% of bleaching on May 2011 and suffered severe death on July 2011. In addition, these genera were the most vulnerable to the coral bleaching phenomenon. However, there were some coral genera that can tolerate to the environmental changes, among them were Diplostrea and Montipora. The coral bleaching also affected the hard coral cover. In every observation points, the percentages of hard coral cover decreased by 10 to 25 %, The highest decrease percentages of hard coral cover occurred in Tourism regions where in 2009 hard coral cover decreased from 43,54 to 32,39% in 2011. This is because in this region, bleaching index (BI) reached the highest value of 77.07% than in Panglima Laot region and Free Zone which only reached 60.78% and 58.50%, respectively. The high levels of coral mortality resulted to the increasing of algal recruitment or raise percentages of Algal cover. The highest Algal cover found in Sumur Tiga and Ujung Seurawan. Both location showed the raise percentages of Algal cover in 2011 which were 20-35% (48,7% and 51,7%) than in 2009 (13,8% and 32,8%).

Saat ini tekanan yang dialami oleh terumbu karang yang paling besar adalah faktor kegiatan manusia, seperti pencemaran dari daratan dan praktek perikanan yang merusak dan telah dianggap sebagai bahaya untuk terumbu karang. Namun sementara masalah ini belum juga terpecahkan selama beberapa tahun belakangan ini telah muncul ancaman lain yang lebih potensial. Fenomena alam yang mengakibatkan tekanan bagi terumbu karang khususnya kenaikan suhu air laut yang dapat mengakibatkan tingginya tingkat pemutihan karang (Coral Bleaching) yang berujung pada kematian karang tersebut. Kematian karang yang diakibatkan oleh fenomena kenaikan suhu permukaan laut yang berujung menjadi coral bleaching atau pemutihan karang pada saat ini semakin sering terjadi dan akan diperkirakan terus meningkat dengan perubahan iklim global. Fenomena Pemutihan karang secara besar-besaran telah terjadi di Samudera Hindia hingga Asia Tenggara dan tidak luput juga lepas pantai Sumatera terutama di Pulau Weh Aceh yang disebabkan oleh naiknya suhu permukaan laut. Berdasarkan NOAA 2010, suhu permukaan laut atau Sea Surface Temperature (SST) di daerah tersebut memuncak pada akhir Mei 2010. Suhu air laut saat itu mencapai 33oC, yaitu 4oC lebih tinggi dari suhu rata-rata normalnya yaitu hanya berkisar 28-29 oC.