Sand addition alters the invertebrate community of intertidal coralline turf

Many rocky intertidal areas are subject to periodic sand inundations due to a natural cycle of sand movement that is being altered and intensified by human activities. Though sand is thought to be a major structuring force in intertidal communities, little experimental research has been done to investigate its effects on intertidal organisms. Assemblages of meio-and macrofauna that inhabit intertidal coralline algal turf have been especially neglected in regards to manipulative research on the effects of sand. In this study sand was added daily to coralline turf plots to maintain depths of either 3 or 6 cm for 1 mo. Within 1 h of sand addition, faunal community composition had changed significantly due to a decrease in the abundances of highly mobile animals. Another shift was seen 2 wk later when abundances of psammophilic gastropods increased. One month after sand addition had ceased, communities in treatment plots again resembled those of the controls. This experiment demonstrated that turf communities rapidly respond to and recover from local physical disturbances due to sand inundation.