Benthic biogeographic patterns in the southern Australian deep sea: Do historical museum records accord with recent systematic, but spatially limited, survey data?

AIM

To document biogeographic patterns in the deepwater benthic epifauna and demersal fishes of southern Australia, and determine whether museum records and systematic survey data provide matching results.

LOCATION

Southern Australian (32-44S) continental slope (200-3,000 m deep).

TAXON

Marine benthic fauna (Arthropoda, Bryozoa, Cnidaria, Echinodermata, Mollusca, Porifera, Sipuncula, and fishes).

METHODS

All available electronic records of fauna from the above taxa and ≥200 m depth off the southern Australian coastline, regardless of organism size, were collated from Australian museums and checked for geographic and taxonomic consistency. These records were then split into 40 geographic segments of roughly equal numbers, with each segment then treated as a sample in multivariate analyses of assemblage composition. Data from a recent (2015) systematic beam trawl survey along five north-south transects in the central Great Australian Bight were also included for comparison.

MAIN CONCLUSIONS

The systematic survey data grouped with the associated geographic segments despite differences in sampling technique (single gear compared to multiple gears), with subsequent differences in taxonomic biases, and the use of a 25 mm mesh, which would undersample some smaller organisms present in the museum data. Thus, the museum data and the survey data provided the same results for the central Great Australian Bight at the level of the whole assemblage. The main biogeographic break occurred off southeastern Tasmania, with a second substantial break occurring at around the border between New South Wales and Victoria. This indicates the potential for unused museum data to describe biogeographic patterns over regional spatial scales, especially in the deep sea where the expense of collecting new data is relatively high.