MacIntosh et al. Marine Biodiversity Records (2018) 11:23 https://doi.org/10.1186/s41200-018-0158-x RESEARCH Open Access Invertebrate diversity in the deep Great Australian Bight (200–5000 m) H. MacIntosh1*, F. Althaus2, A. Williams2, J. E. Tanner3, P. Alderslade2, S. T. Ahyong4, N. Bax5, F. Criscione4, A. L. Crowther6, C. A. Farrelly1, J. K. Finn1, L. Goudie1, K. Gowlett-Holmes2, A. M. Hosie7, E. Kupriyanova4, C. Mah8, A. W. McCallum1, K. L. Merrin1, A. Miskelly9, M. L. Mitchell1, T. Molodtsova10, A. Murray4,T.D.O’Hara1, P. M. O’Loughlin1, H. Paxton4, A. L. Reid4, S. J. Sorokin3, D. Staples1, G. Walker-Smith1, E. Whitfield1 and R. S. Wilson1 Abstract Background: The Great Australian Bight (GAB) comprises the majority of Australia’s southern coastline, but to date its deep water fauna has remained almost unknown. Recent issuing of oil and gas leases in the region has highlighted this lack of baseline biological data and established a pressing need to characterise benthic abyssal fauna. Methods: From 2013 to 2017, six large-scale systematic surveys of the GAB were conducted from 200 to 5000 m depth, constituting the deepest systematic biological sampling in Australia. Sampling was conducted on soft sediment and hard substrates, both at pre-determined depth intervals along north-south transect lines and at sites of interest identified by multibeam sonar. Results: A total of 66,721 invertebrate specimens were collected, comprising 1267 species, with 401 species (32%) new to science. In addition to the novelty of the fauna, there was a high degree of rarity, with 31% of species known only from single specimens. Conclusions: In this paper, we provide an annotated checklist of the benthic invertebrate fauna of the deep GAB, supplemented with colour photos of live specimens and commentary on taxonomy, diversity and distributions. This work represents an important addition to knowledge of Australia’s deep sea fauna, and will provide the foundation for further ecological, biogeographical and systematic research. Keywords: Deep sea, Infauna, Epifauna, Taxonomy, Biodiversity, Biogeography, Great Australian bight Background Conlan et al., 2015). Faunal records that exist were It is often noted how vast and unexplored the deep sea mostly collected either on an ad hoc basis from com- is, but it is a rare opportunity to explore an almost com- mercial fishing trawls, as part of fisheries bycatch sur- pletely unknown marine region — particularly adjacent veys focussing on fishes and with no systematic to a region famed for its unique biodiversity. Such is the collection of invertebrates, or from a very small number case with the Great Australian Bight (GAB), an area of opportunistic samples taken from a research vessel encompassing most of southern Australia’s coastline. passing through the area. These records are also over- While deep sea exploration in Australian waters dates whelmingly from the shallower (< 1000 m) part of the back to the Challenger expedition and has included sur- depth range sampled during our study (200–4961 m). veys of the Coral Sea (Ahyong, 2012), Norfolk Ridge The recent uptake of deep sea oil and gas leases in the (Williams et al., 2011), Tasmanian seamounts (Koslow et region has highlighted a lack of baseline biological and al., 2001) and Western Australia (McEnnulty et al., environmental data, and established a pressing need to 2011), the GAB has been virtually unsampled below con- characterise the composition, abundance and distribu- tinental shelf depths (200 m) (Currie & Sorokin, 2011; tions of benthic fauna before industry activity com- mences. Two major science programs have been * Correspondence: [email protected] implemented to enhance ecological knowledge of the 1 Museums Victoria, Melbourne, Australia deep GAB: the GAB Research Program (GABRP) (The Full list of author information is available at the end of the article © The Author(s). 2018 Open Access This article is distributed under the terms of the Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. MacIntosh et al. Marine Biodiversity Records (2018) 11:23 Page 2 of 21 Great Australian Bight Research Program, 2017), and sedimentary layers of the Ceduna sub-basin (Williams et the GAB Deepwater Marine Program (GABDMP) (The al., 2018c). As deep sea communities can vary greatly with Great Australian Bight Deepwater Marine Program, both depth and substrate type (Rowden et al., 2016), sam- 2017). These programs have supported six surveys be- pling was designed to cover a full range of bathomes as tween 2013 and 2017 that targeted the benthic diversity well as substrates to ensure a representative collection of of the deep GAB, resulting in a substantial and fauna could be made. high-quality collection of epifauna (animals dwelling at Benthic invertebrates were collected on six offshore sur- or slightly above the surface of the seabed), infauna (ani- veys (Table 1)bytheRVSouthern Surveyor (voyage mals dwelling within sediment) and bentho-pelagic SS2013_C02), RV Southern Supporter (survey FU201301), fauna (suprabenthic). This sampling, and resulting data RV Investigator (surveys IN2015_C01, IN2015_C02 and set, comprise the deepest systematic biological sampling IN2017_C01) and Industry Inspection Vessel REM Etive in Australian waters. This paper provides a detailed (RE2017_C01) (MNF, 2013;MNF,2015a;MNF,2015b). checklist of the benthic invertebrate fauna of the deep Surveys SS2013_C02 and IN2015_C02 sampled stations GAB, with colour photos of live specimens and com- along five transects, at depths of 200, 400, 1000, 1500, mentary on taxonomy, diversity and distributions. This 2000 and 2800 m (30 sites; Fig. 1). Survey FU201301 op- research is intended to underpin further studies analys- portunistically collected biological samples at seven sites ing community structure, macroevolution and biogeo- identified as being of particular interest for the drilling of graphic patterns (Williams et al., 2018a; Tanner et al., exploration wells. The IN2015_C01 and IN2017_C01 sur- 2018). Corresponding treatment of the fishes of the deep veys were focussed on targets of interest at 1000 to GAB has also been completed (Williams et al., 2018b). 5000 m depth, including rocky outcroppings in canyons, All specimens are now stored in Australian museums volcanic seamounts, and potential seep zones (21 sites; and other research institutes where they are accessible Fig. 1). Survey RE2017_C01 used two sub-sea Remotely to researchers conducting taxonomic, and other studies, Operated Vehicles (ROVs) to closely explore five of these ensuring this benthic data set will continue to contribute sites. to knowledge and understanding of the deep sea fauna Biological sampling totalled 304 operations over 58 in local, regional and global contexts. sites, using eight gear types (Table 2, Fig. 1). This mix of site selection and sampling gear ensured that a wide Methods range of habitat types and their associated fauna were Biological sampling sampled. The geomorphology of the GAB is broadly similar to most Epifauna mainly consisting of animals larger than continental margins, with a moderately wide continental 10 mm in size, and living on or just below the sediment shelf (0-200 m depth), continental slope and rise (200– surface, were predominantly collected using three gear 5000 m depth) and large abyssal plain (> 5000 m). The types suited to different terrains. The main sampling tool Ceduna sub-basin, where most sampling took place, fea- was a beam trawl with a mouth size of 4.0 m wide × tures a notably wide, gently descending slope (Sayers et 0.5 m high fitted with a net bag that has a 25 mm al., 2003). The majority of the deep GAB consists of soft stretch mesh cod end, designed at CSIRO (Lewis, 2010) substrates comprised primarily of thick pelagic ooze but adapted from another design (Forest, 1981). This (Rogers et al., 2013). In contrast with this soft, gear was used for sampling flat, soft sediment terrains, homogenous environment are several volcanic seamounts where it recovered nearly 70,000 specimens of inverte- associated with the Bight Basin Igneous Complex (BBIC), brates in 63 operations. Harder and rougher substrates, consisting of heterogeneous, basaltic rock substrates such as seamounts and rocky outcrops were sampled (Williams et al., 2018c). The continental slope also bears a using the ‘Sherman sled’, a CSIRO designed and built ro- series of incised canyons and outcroppings, exposing bust epibenthic sampler with a mouth-size of 1.2 m wide Table 1 Summary of deep water surveys in the Great Australian Bight, 2013–2017, with survey duration and number of sampling operations Survey Name Vessel Dates Depth Range Operations SS2013_C02 RV Southern Surveyor 03.04.2013–22.04.2013 189–2018 m 32 FU201301 RV Southern Supporter 09.04.2013–08.05.2013 478–2095 m 5 IN2015_C01 RV Investigator 25.10.2015–25.11.2015 932–4677 m 66 IN2015_C02 RV Investigator 29.11.2015–22.12.2015 184–3021 m 48 RE2017_C01 REM Etive 10.03.2017–06.04.2017 1338–3079 m 133 IN2017_C01 RV Investigator 10.04.2017–28.04.2017 137–4961 m 20 MacIntosh et al. Marine Biodiversity Records (2018) 11:23 Page 3 of 21 Fig. 1 Map of the central and eastern GAB regions showing the sampling stations from each of the six GAB deep water surveys (marked as coloured circles). The sampling transects (pink lines) and target sites (green shaded) are shown × 0.6 m high, fitted with a 25 mm stretch mesh cod end In addition to the epifauna collections, 75 operations (Lewis, 1999; Lewis, 2009), and a standard Geoscience were conducted to collect soft sediment macro-infauna, Australia design rock dredge.