Dictionary of Ichthyology

zonation = a distinct animal and plant community. Often refers to zonation on a sea shore where fishes, for example, are found at different levels of tidal influence and associated with different plant communities.

Rock on a beach near Kalaloch, Washington showing zonation from Wikimedia Commons: http://commons.wikimedia.org/wiki/File:
Intertide_zonation_at_Kalaloch.jpg