Macrobenthic colonisation of disturbances on an intertidal sandflat: the influence of season and buried algae

This study examines whether macrofaunal colonisation differs seasonally in an intertidal sandflat. Frozen cores were placed in the sandflat within each season and colonisation of these cores was followed for 50 d. This study shows a previously untested effect of buried algal mats on colonisation. A change in the sediment organic content can increase or decrease macrofaunal densities. Community colonisation rates of defaunated plugs were slower in winter compared to summer because of the higher numbers of rare macrofauna in winter. Community colonisation of plugs with algal additions were also dependent on the seasonally varying response of the corophiid amphipod Paracorophium excavatum, the most abundant species in this community. The strongest effect of the experiments was linked to critical densities of P. excavatum, irrespective of season. A mechanism for this linkage is suggested. This study also emphasises the importance of post-settlement movement as the mechanism by which most species on this sandflat colonised in either season.