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Parks Victoria Technical Series No. 79 Flinders and Twofold Shelf Bioregions Marine Natural Values Study Intertidal Soft sediment The intertidal soft sediment is in the north-west of Point Hicks MNP as sand beach fronting an extensive dune system (Ball and Blake 2007). As noted by Plummer et al. (2003) no specific data on the biota on sandy beaches are available in the MNP or nearby. Intertidal soft sediment flora is restricted to macroalgae drift and macroalgal epiphytes. Beach-washed materials in sandy beach habitats are a significant source of food for many shore birds, and contribute to the detrital cycle that nourishes many of the invertebrates, such as bivalves, living in the sand (Parks Victoria 2006c). Reef Rocky intertidal reefs, also called rocky reefs or intertidal platforms, are generally found in Victoria on and near headlands with stretches of sandy beaches either side. Along with beaches, intertidal reefs are one of the most accessible components of the <strong>marine</strong> environment as they are the interface between the ocean and the land (Power and Boxshall 2007). As such they are valued as important habitats by people and tend to be visited more than other sections of the coast (Carey et al. 2007a; Carey et al. 2007b). This means they are often subjected to human pressures like harvesting, fossicking and trampling as well as pressures from pollution sources on land and in the sea (Power and Boxshall 2007). Intertidal reef biota are exposed to large changes in physical conditions such as temperature and desiccation. There is great spatial and temporal variability in the life histories of the organisms and the environmental processes in reef habitats (Underwood and Chapman 2004). The recruitment of new biota onto the reef, from the plankton, strongly influences the ecological patterns for individual species and assemblages. Interactions between biota on the reef also influence biota distribution. Resources which are often in short supply on intertidal reefs are space on which to live and the food itself (Underwood and Chapman 2004). The composition of invertebrate assemblages living on the intertidal reefs at Point Hicks are more similar to those found at Mallacoota, Merimbula and Bermagui than to assemblages found further west along the Victorian coast (Hidas et al. 2007). East coast species contributing to these differences have lower densities at Point Hicks than in NSW (Hidas et al. 2010). The MNP has a relatively narrow band rock platform around the base of Point Hicks itself (Ball and Blake 2007). The remote location of the MNP means that human threats to the intertidal reef such as biota collection and trampling is low, due to this there is has been no intertidal reef monitoring program in Point Hicks MNP. As noted by Plummer et al. (2003) no specific data on the biota on intertidal reefs are available in Point Hicks MNP or nearby. Subtidal Soft sediment Between Whaleback Rock and the isolated reef directly off Point Hicks biogenic gravel, consisting of whole and broken shells often encrusted in pink algae, covers the ocean floor (Holmes et al. 2007a). Shell areas tend to have many small orange ball sponges Tethya in amongst the shells (Holmes et al. 2007a). Sometimes vertical sponges are also present, attached to larger shells (Holmes et al. 2007a). Areas with rippled sand also contains shells in the ripple troughs. These shells are usually covered in pink encrusting algae, possibly indicating the presence of rhodoliths in these areas (Holmes et al. 2007a). Sand areas tend to be bare, although if vegetation is present, it is usually clumps of Caulerpa. Some areas of sand are inhabited by sessile invertebrates; however, as the species of invertebrates observed must attach to a hard substrate, it is assumed that the sand forms a thin veneer over the reef (Holmes et al. 2007a). 53
Parks Victoria Technical Series No. 79 Flinders and Twofold Shelf Bioregions Marine Natural Values Study Depth and sediment affect the distribution of benthic invertebrates along the Victorian coast. According to Coleman et al. (2007) and Heislers and Parry (2007) species richness was greater at 40 metres compared to 10 or 20 metres depth. Their coastal survey of benthic fauna included the benthos of Point Hicks MNP. One transect off Point Hicks was sampled with two 0.1 m 2 grab samples in 10, 20 and 40 m of water depth. The sediment ranged from fine sand to coarse sand with shells (Heislers and Parry 2007). The grab samples contained between 100 to 1130 individuals and 16 to 71 species (Heislers and Parry 2007). Crustaceans were the dominant taxa in each depth class, representing more than half of the most abundant families. The majority of these were amphipods and cumaceans, while isopods and ostracods were also common. Polychaetes represented the bulk of the remaining families while molluscs were poorly represented. Four families were common in all depth classes, including one amphipod family (Phoxocephalidae), and three polychaete families (Spionidae, Syllidae and Paraonidae). The invasive New Zealand screw shell, Maoricolpus roseus, was identified in very high densities at 40 m depth in the Pt Hicks MNP (Heislers and Parry 2007). Where this invasive species was most abundant, the diversity of infauna was reduced, suggesting that this exotic species poses a serious threat to the high diversity of infauna that is characteristic of much of Bass Strait (Heislers and Parry 2007). Trawl surveys conducted off Point Hicks indicate that the dominant fish species on subtidal soft sediment are school whiting Sillago flindersi, sparsely spotted stingaree Urolophus paucimaculatus, piked dog shark Squalus megalops, jack mackerel Trachurus declivis, round snouted gurnard Lepidotrigla mulhalli, red rock cod Scorpaena papillosus and cocky gurnard Lepidotrigla vanessa (Plummer et al. 2003). Other important species include banded stingaree Urolophus cruciatus (Figure 23), short finned gurnard, scaber leatherjacket Parika scaber and gurnard perch Neosebastes scorpaenoides (Plummer et al. 2003). Nearby inshore areas have been identified in recreational fishing guides as hosting gummy sharks Mustelus antarcticus, Australian salmon Arripis trutta and tailor Pomatomus saltatrix (Plummer et al. 2003). Newborn pups of gummy sharks inhabit shallow inshore areas and there is some evidence to suggest that the inshore sandy areas east of Wilsons Promontory, including Point Hicks MNP, may be important feeding areas for gummy shark pups (Plummer et al. 2003). The commercial catch data also indicates that the general area provides suitable habitat for gummy sharks, saw sharks and elephant sharks Callorhinchus milii (Plummer et al. 2003). These shark species are all demersal and so the subtidal soft sediment environment within and adjacent to Point Hicks MNP may provide an important feeding ground for these species (Plummer et al. 2003). Figure 23. Banded stingaree Urolophus cruciatus in Point Hicks Marine National Park. Photo by Mark Norman Museum of Victoria. 54
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4 Appendix 1 Compilation of species
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Biotic group Family Species Common
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Parks Victoria is responsible for m
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