Analysis of the Relationship Between Reef Fish Abundance and Coral Reef Cover in Karimun District, Riau Archipelago (Case Study: Pandan, Seranjau, Resam, Sekatip, Kelawa Besar, Kelawa Kecil, and Sebaik Islands)

Coral reefs play an important role as habitats, spawning grounds, nutrient sources, nurseries, and shelter grounds for reef fish. Damage to coral reefs can affect the diversity and abundance of reef fish. In the waters of Karimun Regency, Riau Islands, coral reefs are under threat due to sand mining activities in the surrounding areas. This sand mining has led to magnesium and potassium pollution, which, if present in excessive amounts, can harm both coral reefs and reef fish. The objective of this study was to determine the relationship between the abundance and diversity of reef fish and coral cover. This study was conducted in September 2023 by using PIT (Point Intercept Transect) and UVC (Underwater Visual Census) methods at 10 stations where each station transect was 50 meters long and water quality data were also collected. The results showed that the average coral cover at the study sites was 53.6% which is considered good. A total of 807 reef fish individual were identified across the 10 stations, belonging to 4 families and 14 species. The reef fish diversity index (H') ranged from 0.917 to 1.502, categorized as low to medium. The abundance of reef fish ranged 0.100 - 0.980. The correlation test between coral cover and reef fish diversity yielded a value of -0.021, indicating a weak negative relationship. Meanwhile, the correlation between coral cover and reef fish abundance showed a value of 0.192, suggesting a positive but weak relationship.