BENTHIC AND REEF FISH COMMUNITIES OF MENJANGAN ISLAND CORAL REEF ECOSYSTEM, BALI

• Main Author: Baihaki Kurniawan, Muhammad
• Format: Final Project
• Language: Indonesia
• Online Access: https://digilib.itb.ac.id/gdl/view/68537
• Institution: Institut Teknologi Bandung

Menjangan island of West Bali National Park is a strategic area for coral reef conservation, marine tourism and fisheries. Even though its coral reef ecosystem is considered in a “good” condition, previous research suggested that some coral communities in several localities have been degraded. This research was conducted to: (1) inventorize benthic and reef fish communities components; (2) compare benthic and coral reef fish communities between several observation stations; and (3) determine level of ecosystem health for several observation stations around Menjangan Island. Data collection was conducted from 24 to 26 April 2022 in the reef flat zone (depth <3 m) of three observation stations: (1) Mangrove Point station (MP); (2) Pos 1 station (P1); and (3) Pos 2 (P2). Data taken were consisted of: (1) water phyisical parameters; (2) benthic and reef fish components; and (3) benthic and reef fish communities structures. Our results indicate that Menjangan Island’s coral reef ecosystem has at least 24 genera of benthic organisms with 29.5% coral cover habitated by 88 species of reef fish from 21 families. It’s poor water quality is below the national physical standards except for water acidity parameter. Further analyses suggested that even though there is no significant differences in water phyisical parameter among stations, they have different benthic and reef fish communities. Mangrove Point station has “poor” coral cover (14.25%), lowest number of benthic genera (9), highest algae cover (50.25%), lowest number of coral reef fish encounters (557), lowest reef fish species (53), and highest coral mortality index (0.72); suggesting phase shift which has turned coral reef into algal ecosystem. Presence of rubble-associated fish from Family Apogonidae, Gobiidae, Tetraodontidae, and Pinguipedidae and reef fish indicator from family Chaetodontidae is indicating habitat variation within this station. Pos 1 station has “good” coral cover (27.5%), highest percentage of mobile substrate (47.5%), highest number of reef fish species (56), and coral mortality index of 0.62; indicating damaged benthic community that has not affected the reef fish community although it is very likely to be less diverse in the near future. Pos 2 station has “good” coral cover (46%), highest number of benthic genera (19) and reef fish encounters (1.768), with lowest coral mortality index (0.269). In addition, it has six unique species with high associations to coral cover as well as mesopredators (e.g., Tylosurus crocodilus). Considering these, P2 station has the healthiest coral reef ecosystem among the three, representing the original condition of Menjangan Island’s reef flat ecosystem. Lastly, based on the ecosystem health assessment approach, there were different health conditions of coral reef ecosystem among stations; with MP, P1 and P2 stations subsequently have “enough", “good”, and “good” health condition level. It shows that the local conservation authority should also consider this variation to enforce a proper and better conservation management of Menjangan Island’s coral reef ecosystem.