Natural values of the Solitary Islands Marine Park - Marine Parks ...

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14 Natural values of the Solitary Islands Marine ParkFigure 14.High resolutionbathymetric image of theseabed of 40 Acres Reef(Sidney Shoals) in themarine park.4.1.1 Inshore reefsThere are inshore reefs in much of the marine park, mainly adjacent to headlands thatalso contain intertidal rocky shores. Large inshore reefs occur between Jordans Creekand Moonee Creek, between Woolgoolga Headland and Arrawarra Headland, andbetween Station Creek and Wooli Wooli River. Smaller areas of reef occur adjacent toother headlands and intertidal platforms (Figure 13). Reefs closer to shore are morecommon in the southern half of the marine park.Like most shallow inshore reefs in NSW, reefs in the marine park are characterisedby abundant macroalgae (Millar 1990, 1998), dominated by the kelp Ecklonia radiata(Figure 16), and various species of Sargassum and Caulerpa (Smith and Simpson 1991a,Harriott et al 1994, Mau et al 1998). They generally contain an understorey of corallinealgae and a diverse range of foliose algae, including species of Zonaria, Rhodymeniaand Ulva (Kennelly 1995, Edgar 1997). There are also sponges and sessile invertebrates(those that attach themselves to the seabed or other species) on shallow reefs, butthese are not generally the dominant assemblages.The species composition of algal assemblages is determined primarily by depth,exposure to swell, distance offshore and patterns of recruitment and grazing, andtherefore varies within and between reefs. Generally, throughout the marine parkthe cover of larger macroalgae decreases with distance offshore (Harriott et al 1994).However, at any one particular site, there may be zonation (particular distributions ofspecies in zones).Barnacles and solitary ascidians (sea squirts), such as the pyurids Herdmania momusand cunjevoi Pyura stolonifera, can also be dominant on shallow exposed reefs, as canareas of bare rock with microalgal communities. Corals do occur on these reefs butprimarily as a small component of the understorey assemblage. Some inshore reefshave specific values that are significant to the region. For example, the reefs fringingMuttonbird Island have high algal diversity, with occurrences of two rare endemicalgae species Valeriemaya maculata and Baldockia verticellata (Millar pers. comm.).
Ocean ecosystems 154.1.2 Mid-shelf reefsMid-shelf reefs occur extensively throughout the marine park, including fringingreefs around three of the main islands in the Solitary Islands Group – Split SolitaryIsland, South West Solitary Island and North West Solitary Island – and numerousfully submerged reefs (Figure 13). Many mid-shelf reefs are less than 25 metres deep,although several reefs, particularly on the eastern side of the mid-shelf region, aredeeper. Given the limited swath-mapping of mid-shelf habitats in the marine park, it islikely that there is much more reef than is represented in Figure 13. Mid-shelf reefs thathave been mapped include:• full subtidal reefs (e.g. 40 Acres Reef – also known as Sidney Shoals);• island-associated reefs (e.g. around South West Solitary Island, also known as GroperIsland).The 40 Acres Reef consists of a continuous central reef area, surrounded by a large areaof patchy reef with a lower profile and level of complexity (Figs. 14 and 15). Most of thereef is shallow, extending into intermediate depths only to the south and east. Anotherlarge mid-shelf subtidal reef system, that is considerably more extensive than indicatedfrom earlier mapping, occurs between Station Creek and the Wooli Wooli River, withshallow reef on the western side extending into intermediate depths further east.A large area of continuous shallow reef surrounds South West Solitary Island. Furthereast and south-east, the reef extends into intermediate depths and becomesincreasingly patchy. Shallow, mid-shelf reef systems are also present around SplitSolitary Island and North West Solitary Island.Benthic habitats around several mid-shelf islands have been mapped at a fine scale,including at Split Solitary, South West Solitary and North West Solitary islands (Smithand Edgar 1999). Islands are fringed by a range of different reef habitats, includingthose dominated by coral, kelp, boulders, gravel, algae and urchin barrens (areas wherepopulations of sea urchins have overgrazed kelp beds) (Smith and Edgar 1999). HabitatFigure 15.Three-dimensionalbathymetric image of theseabed at 40 Acres Reef,looking westward.
Page 1 and 2: Naturalvalues of theSolitary Island
Page 3: ContentsGlossary1 Introduction . .
Page 6 and 7: littorinid snails: species of mollu
Page 8 and 9: 2 Natural values of the Solitary Is
Page 10 and 11: 2 Physical environment2.1 ClimateTh
Page 16 and 17: 3 Ecosystems and habitatsBiological
Page 18 and 19: 4 Ocean ecosystemsConsolidated area
Page 22 and 23: 16 Natural values of the Solitary I
Page 32 and 33: Figure 37.Station Creek.5 Estuarine
Page 38 and 39: 6 Pelagic ecosystemsOcean currents

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