The effects ofpatch size and substrate isolation colonization modes and rates in an intertidal sediment

The dynamics of soft-bottom disturbance mosaics may be strongly influenced by life stages of colonists, disturbance size, and patch isolation. We assessed the effects ofpostlarval immigration, patch size, and vertical isolation colonization following small-scale disturbance ina mudflat in Barnstable Harbor, Massachusetts. Defaunated sediment plugs of two sizes (50 and 1,750 cm2 in plan area) and two levels of isolation (flush with the seafloor and elevated 5 cm) were implanted in the flat and sampled after 4-41 d. Postlarval immigration proved a major colonization mode for both treatment sizes. Colonization rates and successional patterns varied markedly between patch sizes, however. Fauna1 abundance and species number increased more rapidly, and species proportions differed, insmaller treatments primarily because the contribution fpostlarval im-migration varied inversely with patch size. Colonization i elevated plugs bore little r semblance to that in flush treatments, with macrofauna ccumulating in raised plugs at markedly lower rates. We conclude that postlarval immigration may be a major mode of colonization atour site and perhaps in soft bottoms generally, following small-scale disturbance, that patch size must be considered in models of benthic olonization a d succession, and that interpreting results fro