A quantitative understanding of the distribution of epibenthic taxa on continental shelf regions is vital for evaluating the effectiveness of Marine Park management plans. However, reefs that support much of these epibenthic taxa in the temperate regions of the Australian Marine Park network are often low-profile, sand-inundated, and spatially constrained. These characteristics make the quantification of epibenthic communities a challenge.
Seabed mapping using multibeam sonar during the NESP Marine Biodiversity Hub survey of the Beagle Marine Park revealed that the area is dominated by soft sediments, with localised areas of low-profile reef, including rare examples of relict terrestrial dunes that formed when Bass Strait was a land bridge during the last ice age.
Underwater imagery collected using the IMOS Autonomous Underwater Vehicle ‘Sirius’ revealed that these low-profile reefs provide habitat for a sponge-dominated epibenthic assemblage. The adjacent soft-sediment areas consist of extensive fields of biogenic rubble and doughboy scallop beds that provide important additional habitat for the epibenthic assemblages in the Park. While not identified in multibeam backscatter data, these extensive biogenic rubble fields and scallop beds appear to form mesophotic analogs of shallow-water shellfish reefs, which are known for their ecological and economic value. We suggest that these mesophotic shellfish reefs represent an important and potentially undervalued natural value of the Park. The data collected in the Park also represent an important reference for ongoing monitoring of these reef communities.