Corals differential susceptibilities to bleaching along the Red Sea Coast, Egypt

Mohammed Shokry Ahmed Ammar, Ahmed Hamed Obuid-Allah, Montaser Aly Mahmoud Al-Hammady

Abstract. Ammar MSA, Obuid-Allah AH, Al-Hammady MAM. 2011. Corals differential susceptibilities to bleaching along the Red Sea Coast, Egypt. Nusantara Bioscience 3: 73-81. Coral bleaching was studied at four sites in four widely geographically separated areas. Three of these sites are subjected to different human activities and the fourth one is considered as a control site. Data were collected by using SCUBA diving equipments and the line transects method. A total of 3940 coral colonies, representing 62 species in 21genera and 10 families, were recorded on transects on the reefs of four studied sites.20.11% of all corals were affected by bleaching: 5.4% were moderately affected; 2.7% severely affected and 12.007% were dead. Overall, there were differences in the proportion of colonies affected by bleaching between the studied sites. Ras El-Behar, the site impacted by petroleum oil, has the maximum average proportion of moderately, severely bleached and dead colonies. While, the lowest average proportions of severely bleached colonies and dead colonies were found at Kalawy bay. Surprisingly, coral reef taxa at El-Hamraween harbor showed high resistance to bleaching probably because of having a new different clade of Symbiodinium which can withstand sea water temperature. Species with highest susceptibilities to bleaching in areas of oil pollution, increased sedimentation and heavy load of phosphate are Stylophora pistillata, Acropora granulosa and Montipora meandrina, respectively while species with lowest susceptibilities are Fungia fungites, Alveopora daedalea and Millepora dichotoma, respectively.

Key words: coral, bleaching, eutrophication, oil pollution, sedimentation, Red Sea.

Abstrak. Ammar MSA, Obuid-Allah AH, Al-Hammady MAM. 2011. Kerentanan diferensial karang terhadap pemutihan di sepanjang Pantai Laut Merah, Mesir. Nusantara Bioscience 3: 73-81. Pemutihan karang dipelajari di empat lokasi pada empat wilayah geografis yang terpisah secara luas. Tiga dari lokasi ini dipengaruhi aktivitas manusia yang berbeda dan lokasi yang keempat dianggap sebagai lokasi kontrol. Data dikumpulkan dengan menggunakan peralatan menyelam SCUBA dan metode garis transek. Sebanyak 3940 koloni karang, yang mewakili 62 spesies dari 21genera dan 10 famili, tercatat pada transek yang mewakili empat lokasi terumbu karang yang dipelajari. 20.11% dari semua karang mengalami pemutihan: 5,4% cukup terpengaruh; 2,7% terkena dampak parah, dan 12,007% mati. Secara keseluruhan, terdapat perbedaan proporsi koloni yang dipengaruhi oleh pemutihan antara masing-masing lokasi yang dipelajari. Ras El-Behar, lokasi yang dipengaruhi oleh minyak bumi, memiliki proporsi merata antara koloni yang cukup, parah dan mati. Sementara, proporsi rata-rata terendah dari koloni yang parah dan mati ditemukan di teluk Kalawy. Mengejutkannya, terumbu karang di pelabuhan El-Hamraween menunjukkan resistensi yang tinggi terhadap pemutihan kemungkinan karena memiliki kelompok baru Symbiodinium yang berbeda dan dapat menahan suhu air laut. Spesies dengan kerentanan tertinggi untuk pemutihan di lokasi yang mengalami pencemaran minyak, peningkatan sedimentasi dan fosfat secara berturut-turut adalah Stylophora pistillata, Acropora granulosa dan Montipora meandrina, sementara spesies dengan kerentanan terendah secara berturut-turut adalah Fungia fungites, Alveopora daedalea dan Millepora dichotoma.

Key words: karang, pemutihan, eutrofikasi, polusi minyak, sedimentasi, Laut Merah.

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