Artificial substrate and coral reef restoration: What do we need to know to know what we need

To use artificial substrate effectively in coral reef restoration certain b asic knowledge is required: (1) what is the artificial substrate expected t o accomplish relative to the goals of the restoration effort and (2) what a re the expected interactions of the selected substrate's composition, textu re, orientation, and design with the damaged environment and the biota of i nterest, Whereas the first point is usually clear, at least in general term s, the second is not. In this review, we examine: the functions of artifici al substrate in restoration and some of the physical (i.e., composition; su rface texture; color and chemistry; and design in terms of profile, shelter , shading, size and configuration, settlement attractants, and stability) a nd environmental factors (i.e., temperature, light, sedimentation, surround ing biota, hydrodynamics, depth, and temporal effects) affecting these func tions. We conclude that until substantial additional research is accomplish ed, the use of artificial substrate in coral reef restoration will remain a 'best guess' endeavor. Areas requiring additional research are identified and some potentially promising lines of inquiry are suggested.