Kondisi Kesehatan Terumbu Karang berdasarkan Kelimpahan Ikan Herbivora di Perairan Kecamatan Pulau Tiga Kabupaten Natuna

Abstract

Pulau Tiga sebagai salah satu kecamatan di Kabupaten Natuna merupakan kawasan yang didominasi oleh wilayah laut dengan sumberdaya laut yang sangat potensial, khususnya terumbu karang. Di sekitar kawasan terumbu karang, kegiatan penangkapan ikan telah dilakukan secara intensif oleh nelayan lokal dan nelayan luar dengan menggunakan bahan peledak (bom) dan beracun (bius/potas). Konsekuensinya, ekosistem perairan yang telah dieksploitasi di daerah tersebut, membutuhkan waktu untuk melakukan pemulihan secara alami agar dapat mempertahankan dan mengembalikan kualitas dan kuantitas sumberdaya yang tersedia. Khusus untuk ekosistem terumbu karang, salah satu faktor yang mempengaruhi tingkat pemulihannya adalah tersedianya substrat keras di suatu dasar perairan sebagai tempat penempelan larva hewan karang.

The research was conducted in Pulau Tiga Subdistrict, Natuna District, Riau islands Province from April to August 2009. Pulau Tiga is an area dominated by a sea area with marine resource potential, particularly coral reefs. Around the area of coral reefs, fishing activities have been carried out intensively by fishermen using explosives (bombs) and toxic (potassium). Consequently, aquatic ecosystems have been exploited, take time to make a natural recovery in order to maintain and restore the quality and quantity of available resources. Especially for coral reef ecosystem, one of the factors that influence the resilience rate is the availability of hard substrate in a bottom waters as a settlement for coral larvae. Herbivorous animal has a major influence in determining the rate of coral reef animal larval settlement on a substrate because it can prevent the occurrence of a macro-algae excessive closure of hard substrate. This study was aimed to know the relationship between the conditions of the abundance of herbivorous fish with coral reef recovery rate. The methods used were the square transect for determining the condition of coral reefs, growth of juvenile corals and algae cover (DCA), whereas for the determination of herbivorous fish community structure using modification of Line Intercept Transect (LIT), Quadrat Method (QM) and Underwater Fish Visual Census (UVC). The analysis used was standard ecological analysis, correlation test, linier regression and multivariate analysis to find the relationship between the abundance of herbivorous fish, algae (DCA) and coral reefs. The results showed that coral reefs ecosystem in the area are still in good condition with live coral cover average of 63.17%, and shown an indication of an increase in the percentage of coral cover which previously <25%. The result of multivariate analysis can be stated that the higher the abundance of herbivorous fish, then live coral cover and growth of juvenile corals increasing, and decreasing algae cover on coral reef ecosystems. The results of correlation test, multivariate analysis and linear regression (t-Student test), show that from 24 species of herbivorous fish recorded then obtained three species of herbivorous fish that play a role in herbivory in stabilizing coral reefs ecosystem in Pulau Tiga Subdistrict, they are Chlorurus microrhinos, Scarus rivulatus and Siganus doliatus.