Is habitat amount important for biodiversity in rocky shore systems? A study of South African mussel assemblages

Abstract

Habitat-forming species on rocky shores are often subject to high levels of exploitation, but the effects of subsequent habitat loss and fragmentation on associated species and the ecosystem as a whole are poorly under - stood. In this study, the effects of habitat amount on the fauna associated with mussel beds were investigated, test- ing for the existence of threshold effects at small landscape scales. Specifically, the relationships between mussel or algal habitat amount and: associated biodiversity, associ- ated macrofaunal abundance and density of mussel recruits were studied at three sites (Kidd's Beach, Kayser's Beach and Kini Bay) on the southern and south-eastern coasts of South africa. Samples, including mussel-associated macro- fauna, of 10 × 10 cm were taken from areas with 100 % mussel cover (Perna perna or a combination of P. perna and Mytilus galloprovincialis) at each site. The amount of habitat provided by mussels and algae surrounding the