REEF FISH ASSEMBLAGE ON ARTIFICAL REEFS OF VARYING AGES AT MENGIAT BEACH, NUSA DUA, BALI

• Main Author: Rafi Nugraha, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/67935
• Institution: Institut Teknologi Bandung

Coral reef restoration aims to assist in the recovery of reef ecosystem structure, function, and key reef species in the face of anthropogenic threats over the last few decades. A common method in restoring reef ecosystem is by using artificial reef structures as substrates for coral growth. Since 2016, artificial reef structures called ‘reef stars’ have been established over time in the coastal waters of Mengiat Beach, Nusa Dua, Bali forming several artificial reefs with varying ages. This study aims to compare the reef fish assemblage on artificial reefs of varying ages at Mengiat Beach, Nusa Dua, Bali. Chronosequence approach was used to compare fish assemblages in four stations: three artificial reefs with varying ages (8 months, 1 year and 5 years after deployment) and one sand-rubble flat as pre-restoration habitat. Live coral cover in each station was measured using point intercept transect method. Reef fish assemblages were observed in seven surveys using stationary point count method in December 2021. Coral Fish Diversity Index (CFDI) values of the three artificial reefs are very poor (8 months and 1 year) or poor (5 years). However, species richness, diversity and fish abundance in all three artifial reefs are significantly higher than in the sand-rubble flat. As the artifial reef matured, live coral covers increased, followed by significant increase in species richness and fish abundance. Highest species richness and abundance (33.9±8.9 species; 216.0±63.3 individuals) were observed in the oldest artificial reef (5 years), while the lowest (20.3±3.0 species; 55.9±6.6 individuals) was observed in the youngest artificial reef (8 months). Gradual change in species composition was observed where species composition in the youngest reef is more similar to sand-rubble flat whereas the oldest reef has the most dissimilar species composition. Artificial reefs have higher functional group diversity compared to sand-rubble flat where corallivore species were also absent. As the artificial reef matured, relative abundances of generalist carnivore, invertivore, omnivore, facultative corallivore and algal grazer decreased while planktivore and obligate corallivore increased due to their strong association with live coral cover. This study shows that with increasing artificial reef age, species richness and abundances increased while community composition shifts with the addition of species that are more specialised to coral reef habitat.