Poster Australian Marine Sciences Association 2022

Classification and Mapping of Polychaete Reefs in the Coorong, South Australia.  (#473)

Laura A Schroder 1 , Sabine Dittmann 1
  1. Flinders University, Adelaide, SA, Australia

Biogenic reefs are three-dimensional carbonate structures which support biodiversity by increasing habitat heterogeneity in coastal ecosystems. Recently, polychaete reefs have been considered as ‘marine animal forests’ worthy of protection. The cosmopolitan species Ficopomatus enigmaticus is one of the most prominent providers of polychaete reefs, building circular bioherms that are known to reach 7 m in diameter, and 0.5 m in height. In the Coorong, F. enigmaticus provides a unique habitat in an otherwise soft sediment environment, with structural morphologies following either a circular, irregular or platform type. Individual reef areas vary from 0.29–252 m2 in the brackish waters of the Murray estuary, to 0.37–542 m2 in the marine conditions of the North Lagoon. Satellite imagery has revealed large densities in the North Lagoon, where on average there are 334±68 reefs per 1 km2. The most common reef morphology in the North Lagoon is circular (65%), with the largest diameter recorded being 12 m, exceeding that of previous known F. enigmaticus reef sizes in other coastal lagoons. Preliminary results from sonar and ground truthing on the 3D topography of F. enigmaticus reefs suggest that reef height can reach a maximum of 0.7–1.2 m.