New sampling highlights undescribed diversity in the deep Great Australian Bight

In the face of increasing economic exploration of the deep sea, characterizing benthic diversity is key to monitoring impacts but for much of southern Australia there is little data to draw upon. To aid management decisions in... [ view full abstract ]

In the face of increasing economic exploration of the deep sea, characterizing benthic diversity is key to monitoring impacts but for much of southern Australia there is little data to draw upon. To aid management decisions in the deep Great Australian Bight (GAB), a wide-ranging quantitative and taxonomic survey of benthic macrofauna was undertaken to establish base-line biodiversity data for the region. Benthic sampling was conducted along five transects spanning depths from 200 to 2000 m in the central GAB. A KC6 multicorer was used to collect environmental and sediment cores.

Sediment core samples produced 371 specimens of macrofaunal invertebrates across 8 major groups, with 129 unique species, of which 67 (52%), were undescribed. The majority of species were rare, known only from single individuals. Across the entire study, 73% of species were recorded only from single sites, with 84% from one or two sites. A rarefaction curve showed steady accumulation of species with continued sampling and little evidence of any asymptote – indicating the rate of macrofaunal species accumulation will remain high in any further sampling of deep GAB sediments. There was little species overlap between taxa found in the GAB and those found at comparable depths in other areas of temperate Australia. This suggests the deep waters of southern Australia host an invertebrate fauna that is regionally endemic, but still incompletely known.