Patchiness in assemblages of epiphytic macroalgae on Posidonia coriacea at a hierarchy of spatial scales

Epiphytic algae are important contributors to ecological functions in seagrass ecosystems, However, little is known about the spatial scales at which epiphytic algae vary. Such information is vital for elucidating processes that structure assemblages, and for providing information on variability important for designing comparative and experimental studies. In this study, we examined variation in assemblages of epiphytic macroalgae on Posidonia coriacea at a hierarchy of spatial scales. We sampled according to a nested hierarchical design, with samples separated by distances ranging from centimetres to kilometres. The largest differences were associated with samples separated by kilometres. Differences at the scale of hundreds of metres were comparable to differences at the scale of metres, suggesting that patchiness at the scale of metres was the dominant pattern at scales less than a kilometre. Patchiness at the scale of metres may have been related to differences in shoot density. Patchiness at this scale might be an important feature of epiphyte assemblages, and should be considered in designs of studies.