Moderate relative size of covered and non-covered structures of artificial reef enhances the sheltering effect on reef fish

Identifying the relationship between fish aggregations and artificial reefs (ARs) is important for optimizing reef structures protecting marine resources subjected to external disturbance. Yet, knowledge remains limited of how distribution affected by shelter availability provided different AR structures. Here, we tested effects two structural attributes on a benthic juvenile (fat greenling, Hexagrammos otakii ). We used laboratory mesocosm experiment with simplified unit that was made covered structure non-covered structure. The defined as area inside ARs effective shelter. along edge ARs, which attracts but has lower sheltering effects. Four scenarios orthogonal contained in were implemented: size (small versus large shelter) edge), forming three ratios shelters edges (low, medium, high). four evaluated based changes patterns under found had better effect than small shelter, its edge, especially when density high. In contrast, compared edge. Thus, moderate shelter-edge ratio enhanced ability fat greenling elude Our findings highlight importance quantifying composition affects distributions, providing guidance optimize