Consistencies over regional scales in assemblages of mobile epifauna associated with natural and artificial plants of different shape

Epifaunal invertebrates associated with natural habitat types (wide-leaved and narrow-leaved Sargassum) and artificial habitat types (filamentous and foliose artificial plant units (APUs)) were investigated at paired sites nested within three tropical locations. Differences in species richness, faunal productivity and species composition between natural and artificial habitats were considerably less than differences between locations and differences between the two APU types. Location effects were consistent amongst all habitat types, indicating that APUs provide a valuable tool for monitoring the marine environment, particularly given low variability between samples collected at scales <1 km. Moreover, faunal productivity showed little variation within habitat and location, a result that supports the hypothesis that resource ceilings restrict epifaunal population growth to predictable levels. Species exhibited varying levels of host specificity between locations. At Brook Island and Fantome Island sites, the guild of ampithoid amphipod species present was host specific, occurring on natural Sargassum plants but largely absent from APUs; however, many of the same species occurred on APUs at Great Palm Island sites. (C) 2002 Elsevier Science B.V. All rights reserved.