Spatial variability in the composition of macrofauna on intertidal rocky shores along the coast of the Andaman Sea and the Gulf of Thailand, Southern Thailand

Abstract

Scale-dependent spatial patterns of coastal benthic assemblages have been analyzed in many studies, especially in temperate regions, but such analyses are scarce in tropical waters. Hierarchical analysis of variance was performed using data from a nested sampling design to test whether variability in assemblages of midshore macrofauna from rocky intertidal ecosystems on the southern Thailand coastline differs over different spatial scales and whether assemblages on natural and artificial rocky reefs are similar. Analyses revealed that the composition of macrofaunal groups on the coastline facing the Andaman Sea did not differ from that of the assemblage on the Gulf of Thailand coastline; however, significant variation was detected on the scale of region (within coast) and shore (within region). The abundance of some macrofaunal groups differed among coasts and regions, but all groups exhibited high variation between shores. High variation between shores may mask larger-scale patterns in the composition of macrofaunal groups. Interestingly, the composition of macrofaunal groups and abundance of each group were not influenced by the type of habitat, suggesting that artificial structures may provide a habitat for hard-bottom species where the natural hard substrate is lacking.