DEPTH CAN AFFECT POSTSETTLEMENT SURVIVAL OF HALIOTIS-IRIS (MOLLUSCA, GASTROPODA)

Post-settlement survival of Haliotis iris on experimental substrata wa s compared in shallow (1-2 m) and deep habitats (6-8 m). Growth and su rvival of H. iris were significantly greater in deep compared with sha llow habitat over the 16 wk duration of the experiment (135 days posts ettlement). The available cryptic habitat (5-fold difference between t reatments) had no significant effect on growth or survival. Recruits r emained on the exposed coralline surface of experimental substrata for the duration of the experiment. Poor survival in shallow habitat (< 1 % after 16 wk) was associated with greater water movement and lower ac cumulation of fine sediment compared with deep habitat (survival about 10% after 16 wk). Dislodgement or smothering of recruits in shallow h abitat could account for the low survival and growth.