Seagrass macrofaunal abundance shows both multifractality and scaleinvariant patchiness

Spatial patterns of abundance of the whole macrobenthic assemblage and of its 10 most numerous species were examined across hierarchically nested scales within a 0.85 ha area of intertidal seagrass in subtropical Moreton Bay, Queensland. Multifractality characterised the assemblage and all ten dominant species across those scales (c. 33, 130, 530 & 2115 m(2)), with patchiness of assemblage numbers and those of at least some dominants exhibiting scale-invariance. The system displayed several abundance peaks, 12% of stations accounting for 88% of total variance, with many individual dominants showing a series of non-overlapping 'hot-spots'. Scale invariance and multifractality occurred notwithstanding low levels of species interaction consequent on maintenance at very low density. This suggests that critical self-organisation cannot be responsible for such patterning. Contrary to received wisdom, coefficient beta of Taylor's power-law cannot form an index of aggregation, although it does indicate direction of change in dispersion pattern with changing numbers.