Reef fish abundance enhancement through low-cost coral reef restoration practices: a case study in Tioman island, Malaysia

Abstract Coral reefs and their inhabitants are threatened by several anthropogenic impacts worldwide. While active coral conservation activities have emerged aiming to maintain reef ecological functions and services, the effect of coral restoration practices on high trophic levels is still poorly investigated. We assessed the effect of small-sized concrete structures on the fish community by comparing the early fish colonization between a treated area and a coral rubble area (used here as control) over 12 months with a monsoon period in between. The treated area nearly doubled in total fish abundance and species richness compared to the control, showing that this method can locally enhance the community of reef fish. Pomacentrus chrysurus was the dominant species in all areas, although Eviota distigma contributed the most to the average between-group dissimilarity between areas (8%, p = 0.02). Fish abundance also exhibited differences between fish life stages (adult, juvenile) (H = 28.852, p < 0.001), among trophic categories (carnivore, omnivore, herbivore, planktivore, and corallivore) (H = 90.615, p < 0.001), and between community types (cryptobenthic and non-cryptobenthic) (H = 52.084, p < 0.001). These effects seem to be boosted by a monsoon period, as the increase of species richness and fish abundance was steeper after the monsoon. Our study shows a positive influence on the reef fish community from the deployment of small-sized concrete structures and highlights human intervention as an essential factor in recovering these iconic ecosystems.