Shirley J. Sorokin

Infaunal macroinvertebrate assemblages of the eastern Great Australian Bight: effectiveness of a marine protected area in representing the region’s benthic biodiversity

Marine reserves are used widely throughout the world to conserve biodiversity, but in many instances uncertainties exist over how well these areas represent biodiversity at a regional scale (i.e. 100–1000 km). In the present study, infaunal assemblages were examined in the eastern Great Australian Bight (GAB) to evaluate the efficacy of the Benthic Protection Zone of the GAB Marine Park in representing regional biodiversity. Distributional patterns in infauna were further examined in relation to epifaunal species composition and environmental conditions to investigate structural forcing. Grab samples of infauna were collected from the same 65 sites sampled in an earlier survey of epifauna. In total, 240 taxa belonging to 11 phyla were collected. Most taxa were uncommon, with 96% representing less than 2% of the total number of individuals collected and 39% occurring at only one site. Unlike the epifauna, the infauna of the eastern GAB does not appear to be particularly diverse. Sessile filter feeders dominated the infaunal communities of the inner shelf, whereas motile, deposit-feeding organisms dominated the shelf break. As was the case with the epifauna, the highest numbers of taxa and individuals were recorded near the head of the bight and in inner-shelf waters off the western Eyre Peninsula, where productivity is enhanced by upwelling. Cluster analysis identified three community groupings, which were strongly correlated with depth. All three communities and 72% (172) of the 240 taxa collected were represented within the Benthic Protection Zone of the GAB Marine Park, confirming findings from the epifaunal survey that this protected area is well placed to represent the benthic biodiversity of the eastern GAB.

Demosponge Biodiversity in the Benthic Protection Zone of the Great Australian Bight

Summary The Benthic Protection Zone (BPZ) situated in the South Australian section of the Great Australian Bight (GAB) protects marine benthos from anthropogenic disturbances of the sea floor. However, little is known of the marine benthic fauna occurring within the zone. In a baseline study during 2001/02, epibenthic sled sampling of sites inside the BPZ, and in other parts of the eastern GAB, yielded 351 species of sponge. Of these, 109 demosponge species from 32 families and 61 genera were found in the BPZ. Sponge community composition changes across the shelf, with the highest diversity of sponges occurring in shallow inshore waters, declining with increased depth and distance offshore. The sponge fauna is dominated by species occurring in temperate Australia, with little affinity to fauna in tropical Australia.

Megabenthic biodiversity in two contrasting submarine canyons on Australia's southern continental margin

Abstract Submarine canyons are known to play an important role in enhancing productivity in adjacent surface waters, but their influence on the seabed fauna is poorly understood. Here we examine environmental conditions in two canyons with contrasting topographies, and evaluate their relative importance in structuring benthic megafaunal assemblages. Samples of benthic megafauna, sediment and water were collected from five sites at du Couedic Canyon (100–1500 m) and six sites at Bonney Canyon (100–2000 m) off South Australia. Sessile suspension-feeding organisms (primarily sponges, molluscs and cnidarians) dominated samples and comprised 97% of the biomass and 77% of the total species richness (184 spp.). Megabenthic biomass and species richness broadly declined with increasing depth in both canyons, but was markedly higher at du Couedic Canyon in an area subject to organically enriched seasonal outflows from Spencer Gulf. Multivariate analyses showed a strong environmental gradient running perpendicular to the coast in both canyons, and highlighted a progressive shift in species composition. Three station groupings were identified on the shelf (100–200 m), upper slope (500 m) and mid slope (1000–2000 m). These community groupings were largely explained by depth and dissolved oxygen concentration and coincided with depth-related discontinuities in water masses on Australias southern continental margin.

Evaluating the effects of reserve closure on algae, invertebrate and fish assemblages at a temperate South Australian marine reserve

Differences in the reef biota between the Point Labatt Marine Reserve and adjacent unprotected reference areas were examined following an 18-year period of protection from fishing. Quantitative measures of fish, invertebrates and algae were obtained by divers at 1 6 depth-stratified locations inside and outside the reserve, and the significance of differences examined using a combination of univariate (ANOVA) and multivariate (MDS) analyses. Strong depth-related differences in the composition and abundance of algae and invertebrates were observed, both inside and outside the reserve. These community differences were most pronounced in shallow near-shore waters (<10 m depth), and were largely due to variations in the abundance of a small group of species with widespread distributions. Spatial patterns in fish were not closely related to depth, and it appears that trophic linkages between fish and the underlying algal and invertebrate assemblages at Point Labatt are either weak or occur at spatial scales larger than that covered in this study. No significant reserve-related differences were detected in the abundance, diversity or community structures of algae, invertebrates and fish examined in this study. In many cases this is because the biological attributes measured were highly variable in space, and required more intensive sampling regimes to improve statistical precision. This study emphasizes the need for more robust survey designs and their timely implementation in marine conservation planning processes.

The Distribution and Trophodynamics of Demersal Fish from Spencer Gulf

Abstract This paper describes the composition, distribution and diets of demersal fishes collected from Spencer Gulf during a quantitative Gulf-wide trawl survey in February 2007. A total of 132 fish species from 65 families were collected from the 120 trawl shots. Degens leatherjacket, Thamnaconus degeni, was the most abundant species collected (627 ± 239 ha−1). This fish was also dominant in terms of biomass, and accounted for more than 40% of the total catch weight. Most other species (95%) had mean biomasses ranging from less than 1 to 515 g ha−1, and individually contributed less than 3% to the overall catch. Correlation analyses revealed a broad latitudinal gradient in fish abundance, biomass and richness. All three parameters generally increase towards the south of the Gulf, in association with increasing water depths and decreasing water temperatures. Multivariate cluster analyses confirmed the presence of a strong environmental gradient between the north and south of the Gulf, and highlight the presence of three distinct fish assemblages (north, central and south) that are closely allied with changes in depth. Small subsets of species with restricted distributions characterised each regional assemblage. Dietary examinations of the stomach contents of 871 fish representing 107 species were also undertaken during this study. Five feeding guilds were identified from cluster analysis of the stomach contents. These included groups of fish feeding primarily on echinoderms (2 spp), other fish (13 spp), molluscs (11 spp), crustaceans (52 spp) and worms (23 spp). Atrophic model was constructed to evaluate levels of food consumption for each fish, and to assess regional differences in the composition and total volume of prey eaten. Total food consumption was estimated to decrease progressively towards the top of the Gulf, with daily food consumption rates in the northern region (219.55 g ha−1 day−1) more than seven times lower than those in the south of the Gulf (1580.99 g ha−1 day−1). Crustaceans and annelids were the two most important prey items consumed by demersal fish in all three biomes of the Spencer Gulf (north, central, south), and comprised more than 30% and 18% of the total diet, respectively. Our model suggests that almost half a kilogram of crustaceans and worms are consumed daily per hectare in the south of the Gulf. All other prey groups (e.g. molluscs, bryozoans, echinoderms, sponges) are eaten in much smaller volumes, and are individually consumed at daily rates of less than 127 g ha−1 in each biome. Estimates of consumption were broadly consistent with other temperate Australian estuaries. However, as no seasonal replication of sampling was undertaken it remains unclear if observed spatial patterns and trends are temporally robust.

Investigator Group Expedition 2006: Sponges (Porifera)

Abstract The diversity of marine sponges on the rocky reefs surrounding the Investigator Group of islands in South Australia was investigated for the first time. Line intercept transects at Flinders, Pearson and Ward Islands at ~5 m deep, showed the algal dominance of the sub-tidal rocky reefs. Along these transects, quadrat surveys showed low sponge occurrence on upward facing reefs, but in caves and under overhangs sponges and other sessile fauna were dominant. Divers collected 71 sponge species, 10 in the Class Calcarea and 61 in the Class Demospongiae from the reefs of five islands: Flinders, Pearson, Dorothee, Ward and Topgallant. Many of the sponges had evidence of algal or cyanobacterial symbionts, possibly reflecting the clear shallow-water conditions of the sites. There was little overlap between this collection and a previous collection from the Great Australian Bight Marine Park Benthic Protection Zone, with only three sponges in common.

New Frontiers in Sponge Science – the 2013 Fremantle Sponge Conference

On 3–9 November 2013 the 9th World Sponge Conference was held in Fremantle, Western Australia under the theme ‘New Frontiers in Sponge Science’. The 186 participants were greeted with a banner tethered to the statue of Eliza in the Swan River (Figure 1A; list of participants available in Appendix 1). The conference then started with a Welcome to Country ceremony and an icebreaker function at the Western Australian Maritime Museum on Sunday (Figure 1B), followed by 4 days of conference programme at the Esplanade Hotel with 229 presentations (104 full talks, 17 speed talks, 108 posters; Figure 1C–F), a choice of field trips on Friday and a sponge classification workshop at the University of Western Australia on Saturday (Figure 1G). This was the second time that the international forum of sponge science convened in Australia, after the 5th International Sponge Symposium was held in Brisbane (Hooper, 1999). Inviting delegates to Fremantle in Western Australia offered access to a diverse mix of history, culture, restaurants and nightlife, with everything within walking distance, and buses, trains and ferries connecting to Perth City. The other reason for meeting in Western Australia was the high potential for exchange between the various sectors of science, academia, application-uptake, industries and commercial use, policy making and regulation. As a consequence, on the first day of the conference one session was dedicated to presentations in the context of industrial activities, fisheries, monitoring and managing sponge habitats (Appendix 2). On the last day of the conference two sessions were given to biotechnology presentations (Appendix 2). Other sessions covered general ecology, phylogeny, symbioses, taxonomy and population biology (sequence according to number of oral presentations; Appendix 2). The programme and the book of abstracts, as well as a media release can be found on the event webpage (Sponge Conference Committee, 2012), and additional accounts were given by Marshall (2013); Mazard (2013) and Schönberg (2014). The 9th World Sponge Conference differed in several aspects from previous international sponge meetings. During the Fremantle conference parallel sessions were held for the first time, which was controversial. At the two earlier meetings the sponge research community expressed a strong wish to be able to visit every talk, which was previously possible, but at the expense of many delegates not given the opportunity to present a talk. For example, at the 8th Sponge Conference in Girona, Spain, members of the organizing committee excluded themselves from oral presentations, in favour of international and younger delegates. For the Fremantle conference, however, the organizing committee made a decision to allocate a limited number of parallel sessions to accommodate oral presentations requested by every delegate, and in doing so it also reduced the delegate registration costs by finishing the main programme a day earlier than originally planned. Another novelty was realised through a session of 5 minute speed talks, which offered opportunities for rapid communications, which was enthusiastically embraced by a wide range of presenters (Appendix 2). These talks were welcome in the tight schedule and allowed a quick succession of varied topics, but yielded variable feedback. Keynotes delivered by Clive Wilkinson, Bernie Degnan, Ute Hentschel, Manuel Maldonado, Rob van Soest and James Bell were kept to half-hour sessions (Appendix 2), a setting that was received positively. Every evening an opportunity was provided to mingle socially, which included the highly successful Student Meet and Greet Night at the Norfolk Hotel to rapidly integrate students into the science community (Figure 1H), the poster session at the Esplanade Hotel (Figure 1I), a very al fresco gathering at Kailis’ Fish Market to remember scientists no longer with us (Figure 1J), and the conference dinner at the Fremantle Sailing Club (Figure 1K), during which various awards were distributed (Appendix 2) and not one, but three traditional sponge conference songs were presented (Figure 1L; event webpage, Sponge Conference Committee, 2012). Field trips on Friday took parties through Fremantle, to Rottnest Island (Figure 1M) and the Swan Valley. On Saturday a whole day workshop gave 22 participants the opportunity to learn from nine experienced sponge tutors (Figure 1G). Slide presentations and hands-on microscopy sessions demonstrated classical methods in sponge identification and traits typical for sponge orders, and essential databases were introduced (Van Soest et al., 2012, 2016; Hooper et al., 2013; Hall & Hooper, 2014 and databases these feed into), as well as the concept of sponge functional growth forms that can be used for example when sponges need to be characterized from imagery (Schönberg & Fromont, 2014; Althaus et al., 2015). As another first, it was possible to upload posters and slide presentations to the Faculty of 1000 (2000–2016), an open access, Creative Commons license repository that allows citation of otherwise unpublished data for which the author retains copyright. This service was utilized for 34 Internet publications of conference presentations (25 posters, 9 talks). Last, but not

Macrofaunal Patterns in and around du Couedic and Bonney Submarine Canyons, South Australia

Two South Australian canyons, one shelf-incising (du Couedic) and one slope-limited (Bonney) were compared for macrofaunal patterns on the shelf and slope that spanned three water masses. It was hypothesized that community structure would (H1) significantly differ by water mass, (H2) show significant regional differences and (H3) differ significantly between interior and exterior of each canyon. Five hundred and thirty-one species of macrofauna ≥1 mm were captured at 27 stations situated in depth stratified transects inside and outside the canyons from 100 to1500 m depth. The macrofauna showed a positive relationship to depth in abundance, biomass, species richness and community composition while taxonomic distinctness and evenness remained high at all depths. Biotic variation on the shelf was best defined by variation in bottom water primary production while sediment characteristics and bottom water oxygen, temperature and nutrients defined biotic variation at greater depth. Community structure differed significantly (p<0.01) among the three water masses (shelf-flowing South Australian current, upper slope Flinders current and lower slope Antarctic Intermediate Water) (H1). Although community differences between the du Couedic and Bonney regions were marginally above significance at p = 0.05 (H2), over half of the species captured were unique to each region. This supports the evidence from fish and megafaunal distributions that the du Couedic and Bonney areas are in different bioregions. Overall, the canyon interiors were not significantly different in community composition from the exterior (H3). However, both canyons had higher abundance and/or biomass, increased species dominance, different species composition and coarser sediments near the canyon heads compared to outside the canyons at the same depth (500 m), suggestive of heightened currents within the canyons that influence community composition there. At 1000–1500 m, the canyon interiors were depauperate, typical of V-shaped canyons elsewhere. The large number of species captured, given the relatively low sampling effort and focus on the larger macrofauna, support previous studies that identify the South Australian coast as a high biodiversity area.