Evaluasi metode transek foto bawah air untuk penilaian kondisi terumbu karang

Abstract

The study to evaluate the Underwater Photo Transect (UPT) method as an alternative method for assessing the condition of coral reefs has been conducted in Kepulauan Seribu Jakarta in August 2008. The photos were taken at every 1 m interval, along 70 m transect length placed on the substratum parallel with the coastline at 3-5 m depth. Collecting data with other two methods, namely Belt Transect (BT) and Line Intercept Transect (LIT) were also applied at the same transect with UPT method for comparison study. The comparison study among those three methods (BT, LIT and UPT) indicated that the percentage cover for all benthic and substratum (Hard Coral, Dead Scleractinia, Algae, Other Fauna and Abiotic) were not significantly different. On the contrary, the values of hard coral diversity such as the number of species (S), Shannon’s diversity index (H’) and Piellou’s eveness index (J’) were significantly different for three methods. The higher value of S and H was found when BT method was applied, but the higher value of J’ was found when LIT method was applied. MDS analysis shows that the group occured due to the station, not the method. Therefore, even though the values of hard coral diversity were different among three methods, the UPT method could be used to compare the diversity of hard coral among stations. The study on efficiency and accuracy of photo analysis indicated that the technique of selecting 10 sample random point can be used to estimate the hard coral cover, and the technique of selecting 30 sample random point can be used to estimate the coverage of all group of benthic and substratum. Both techniques use photoes with the minimun image area = (40 x 30) cm2 for each frame. If the species of hard coral was recorded, the technique of calculating the area of benthic and substrate must be done based on photoes with the minimum image area = (58 x 44) cm2 Keywords: Underwater Photo Transect, Belt Transect, Line Intercept Transect, condition of coral reefs, coral reefs, photo analysis, transect length per frame. The study on investigation the optimal of transect length indicated that treatment M (1m_1-10&21-30) was the optimal treatment to estimate the hard coral cover, and treatment C(1m_1-50m) was the optimal treatment to estimate the coverage of all group of benthic and substratum. If the species of hard coral was recorded, the treatment C can also be used for comparison study the diversity among all locations of study area. Treatment M (1m_1-10&21-30) use a (2 x 10 m) of transect length where the photoes are taken from frame-1 to frame-10, and frame-21 to frame-30. Treatment C (1m_1-50) use a 50 m of transect length where the photoes are taken from frame-1 to frame-50. The conclusion of this study is: the UPT method can be used as an alternative method for assessing the condition of coral reefs, with three option depend on the objectives of the research, and the various ability of human resources.