Macrofauna of the intertidal sand flats on low wooded islands, northern Great Barrier Reef

An account of the macrofauna inhabiting the mobile substrata of the intertidal zone on low wooded islands in the Northern Region of the Great Barrier Reef Province is given. Excluding mangrove habitats, three main sediment-fauna types can be recognized: (i) well sorted sands forming the sloping beaches of sand cays, colonized by Ocypode , mesodesmatids and hippids; (ii) muddy sand flats supporting a very diverse fauna dominated in most areas by Edwardsia and chaetopterids; and (iii) areas of fine deposit, characterized by Uca, Gafrarium and Marphysa . Some associations of animals, chiefly involving commensal polychaetes and bivalves, are described.