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parks victoria technical series marine natural values study vol 2 ...

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Parks Victoria Technical Series No. 79<br />

Flinders and Twofold Shelf Bioregions Marine Natural Values Study<br />

the MPAs, except Ninety Mile Beach MNP, have both shallow and deep subtidal reef. All,<br />

except for Beware Reef, have extensive intertidal soft sediment habitat or beaches. Flora in<br />

this habitat is restricted to macroalgae drift which, with other wrack material, contributes to<br />

the detrital cycle and is a significant source of food for many shore birds and invertebrates.<br />

All MPAs have subtidal soft sediment habitat, which can have very high numbers of<br />

invertebrate species living on and in it. Subtidal soft sediment and open water are the<br />

dominant habitat types in the MPAs.<br />

In Wilsons Promontory MNP intertidal rocky reef is limited to a narrow band as the shores<br />

are very steep. Intertidal rocky reef is a relatively narrow band rock platform around the base<br />

of Point Hicks and only along the far eastern shore of Cape Howe MNP. The Beware Reef<br />

MS intertidal reef platform provides a haul-out area for Australian Arctocephalus pusillus<br />

doriferus and New Zealand Arctophoca forsteri fur seals. The intertidal reef invertebrate<br />

assemblages in Twofold Shelf are more similar to southern NSW reef than those to the west<br />

along the Victorian coast. There is no intertidal reef monitoring program in either bioregion,<br />

because of limited intertidal reef and low threat from harvesting or trampling.<br />

Ongoing monitoring and focused research projects have described the flora and fauna of the<br />

subtidal reefs in all the MPAs except Ninety Mile Beach MNP. The shallow subtidal reefs in<br />

the MPAs differ in the composition of canopy forming macroalgae species, understorey and<br />

the associated invertebrate and fish assemblages. Common to all MPAs is the blacklip<br />

abalone Haliotis rubra and wrasse spp. The herbivorous, warm water sea urchin<br />

Centrostephanus rodgersii occurs on the reefs in both bioregions and can remove all erect<br />

algae to create ‘urchin barrens’. Warm water fish species such as the damsel fish, including<br />

the one-spot puller Chromis hypsilepis and white-ear damselfish Parma microlepis, are a<br />

feature of Twofold Shelf shallow subtidal reefs.<br />

Wilsons Promontory MNP has a wide range of subtidal habitat types, from low to high wave<br />

exposure creating distinct east west biogeographic patterns. On high exposure reef,<br />

common in the west and south of the MNP, crayweed Phyllospora comosa dominates the<br />

canopy, the seastars Patiriella brevispina and P. vernicina are typical and herring cale Odax<br />

cyanomelax is abundant. On moderate to low exposure reef in the east Ecklonia-<br />

Seirococcus assemblage dominates the canopy, the seastar Nectria macrobranchia is<br />

typical and herring cale O. cyanomelax abundance is low. Urchins Heliocidaris<br />

erythrogramma, blacklip abalone H. rubra and feather stars Cenolia trichoptera are abundant<br />

on shallow subtidal reefs throughout the MNP. Fish species number and abundance is high<br />

compared to shallow subtidal reefs west of Wilsons Promontory MNP. Four species of fish<br />

dominate, the barber perch Casioperca rasor, blue-throated wrasse Notolabrus tetricus,<br />

purple wrasse N. fucicola, long-finned pike Dinolestes lewini and herring cale O.<br />

cyanomelax. The eastern blue grouper Achoerodus viridis is present in low numbers in<br />

Wilsons Promontory MNP.<br />

Subtidal low calcarenite rocky reefs dominated by sessile invertebrates and sparse red algae<br />

occur along Ninety Mile Beach. Preliminary mapping has not located the reefs within the<br />

Ninety Mile Beach MNP, they may have been covered by sand at the time of mapping.<br />

Shallow subtidal rocky reefs in Point Hicks MNP are highly exposed and have varied forms,<br />

from simple to complex providing a wide range of habitats. The canopy is a mixture of P.<br />

comosa and common kelp Ecklonia radiata, with the proportions of these two species<br />

varying according to the habitat, depth and location. The reef beneath the canopy varies<br />

from encrusting and erect sponges to small fleshy red algae. Invertebrate assemblages<br />

include relatively high abundances of the predatory whelk Cabestana spengleri and the<br />

seastar Patiriella calcar, and moderate abundances of blacklip abalone H. rubra and the red<br />

bait crab Plagusia chabrus. Fish assemblages are dominated by large numbers of blue<br />

throat wrasse Notolabrus tetricus and purple wrasse N. fucicola. Other fish species include<br />

the banded morwong Cheilodactylus spectabilis, sea sweep Scorpis aequipinnis, and Maori<br />

114

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