Infaunal biodiversity patterns from Carnarvon Shelf (Ningaloo Reef), Western Australia

Infauna are important in many ecological processes but have been rarely considered in biodiversity assessments of coral reefs and surrounding areas. We surveyed infaunal assemblages and associated environmental factors (depth, seabed reflectance, sediment characteristics) in three areas (Mandu, Point Cloates, Gnaraloo) along the Carnarvon Shelf, Western Australia. This region supports Ningaloo Reef, a relatively pristine coral reef protected by the Ningaloo Marine Park and a Commonwealth marine reserve. Macrofauna were sampled with a Smith-McIntyre grab and sieved through 500 µm. A total of 423 species and 4036 individuals was recorded from 145 grabs, with infauna accounting for 67% of species and 78% of individuals. Rare species (≤2 individuals per species) represented 42% of the total assemblage. Assemblages were significantly different among all three areas, with the most distinct recorded from the southern-most area (Gnaraloo). Although assemblages varied significantly with depth and sediment composition (mud and gravel), these relationships were weak. Results from the current study broadly quantify macrofaunal diversity in the region and identify potential spatial and environmental patterns which will help inform future marine management plans, including the provision of baseline information to assess the efficacy of protected areas in soft-sediment habitats adjacent to coral reefs.

Document type: