A preliminary analysis of the structure of benthic assemblages of surf zones on two morphodynamic types of beach

Abstract

Predictions that there should be more benthic invertebrates and greater diversity in deeper areas and differences in the spatial structure of assemblages on different types of beaches were tested on two Reflective and two Intermediate (Transverse Bar and Rip) sandy beaches around Sydney, New South Wales, Australia. The macrofaunal assemblages of surf zones were more diverse and there were more invertebrates on Reflective than TBR beaches, and there was an increase in number of invertebrates and, significantly, in diversity from 1·5 to 2·5 m depths. There was significant variation in the structure of assemblages among beaches of the same type. Spatial variability in the structure of assemblages on Intermediate beaches was greater than on Reflective beaches. Macrofaunal assemblages varied significantly at a scale of tens of metres across shore, particularly on Reflective beaches.