Colonization of Coral Communities in the Krakatau Islands Strict Marine Nature Reserve, Indonesia (Kolonisasi Komunitas Karang di Kepulanan Krakatau)

Abstract

Pulau-pulau Krakatau memiliki dinamika secara geomorfologi, dan berbagai perubahan fisik yang berlangsung memberikan dampak terhadap biota, termasuk pada proses dan tingkat pergantian suksesi komunitasnya. Tujuan penelitian ini untuk menjelaskan kondisi terkini dan proses kolonisasi komunitas karang, termasuk status kerusakan komunitas karang dan disturbansi lingkungan yang mempengaruhinya. Line intercept transect dilakukan di enam stasiun pada dua kedalaman yang berbeda yakni 5 dan 10m. Sedangkan observasi terhadap komunitas koral dilakukan dengan perekaman video. Hasil penelitian ini menunjukkan bahwa suksesi atau perkembangan komunitas (i.e. kolonisasi) karang yang dijumpai di Pulau Anak Krakatau masih mengindikasikan tahap awal kolonisasi, berbeda dengan komunitas karang yang dijumpai di Pulau Rakata dan Panjang. Diversifikasi komunitas karang di kedua pulau tersebut, menunjukkan dominansi spesies oportunis dan pioner (i.e. Pocillopora dan Seriatopora) yang umum dijumpai di Anak Krakatau sudah tergantikan. Dominansi dari beberapa spesies karang telah mengindikasikan terjadinya proses eksklusi kompetitif di antara komunitas karang. Tiga tipe komunitas karang yang dijumpai dapat dibedakan menurut karakteristik masing-masing kawasan, yaitu komunitas kawasan terpapar, semi terpapar/terlindung, dan terlindung. Kerusakan komunitas karang di Krakatau berdasarkan kriteria indeks kerusakan karang (CDI) sudah termasuk kedalam kategori wilayah “hot spot”, dimana sangat memerlukan perhatian, pengawasan, pengamatan atau restorasi komunitas karang. Hasil penelitian ini memberikan gambaran bahwa terjadinya kolonisasi dan tingkat kerusakan komunitas karang perlu menjadi acuan dalam pengelolaan kawasan terumbu karang di Cagar Alam Laut Krakatau. Kata kunci: kolonisasi, suksesi; komunitas karang; pengelolaan; Krakatau Krakatau Islands diversity is geomorphologically dynamic, and these physical changes influence on organisms including community successional. The purposes of this research were to determine the condition and describe the recent colonization development of coral communities in the Krakatau Islands after sterilization. Transects were done at six stations at two different depth (i.e. 5 and 10 m) using line intercept transect. While observations of coral communities were done with video transect. This study showed that succession or development of coral communities (i.e. colonization) that found in Anak Krakatau indicated earlier stage of colonization. It has different coral communities compared with those that found in Rakata and Panjang island. The diversification of coral communities on both islands, showed that opportunistic and pioneer species (i.e. Pocillopora and Seriatopora) that generally found in Anak Krakatau has been replaced. There are indications of dominance may already take place through competitive exclusion in the coral communities. Three community types were distinguished based on characteristics for each sites, as follows: communities of wave-exposed habitats, communities of semi- exposed to sheltered habitats, and communities of sheltered habitats. The extent of coral damage covered all six sites based on coral damage index (CDI). This suggests that of the all transects were "hot spots'' that required management action. These results indicate that colonization and the level of coral damage have to be taken into account on the manegement of coral ecosystem in the region. Keywords: colonization; succession; coral communities; management; Krakatau

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