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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 Victorian Embayment bioregion is a discontinuous region that contains the major<br />

embayments, inlets and some of the major estuaries along the Victorian coast (Figure 1,<br />

IMCRA 2006). Within the bioregion, there are five MNPs, Port Phillip Heads in Port Phillip<br />

Bay, Yaringa, French Island, Churchill Island in Western Port, and Corner Inlet. Port Phillip<br />

Heads MNP is discontinuous and consists of six sites in the southern region of Port Phillip<br />

Bay. Three MSs, Point Cooke, Jawbone and Ricketts Point in Port Phillip Bay, also occur in<br />

the bioregion. The climate is moist temperate, with a pronounced west to east variation in<br />

catchment run off and seasonality. Variations in salinity and temperature are much higher<br />

than on the open coast (Parks Victoria 2003). The embayments have a variety of forms from<br />

drowned river valleys to impounded drainage behind dune barrier systems, their maximum<br />

depth is generally less than 20 m, but reaches depths of approximately 50 m in Port Phillip<br />

Heads. They have low energy coastlines with large tides, influencing the extensive areas of<br />

subtidal and intertidal sediments. Rock outcrops are limited mainly to the margins (IMCRA<br />

2006). Some shallow reef areas are present in Port Phillip and Western Port (Parks Victoria<br />

2003). The biota of the Victorian embayments include a diverse range of biotic assemblages<br />

found in estuarine and open coast environments depending on their morphological and<br />

hydrological characteristics (Parks Victoria 2003; IMCRA 2006). Port Phillip Bay is a <strong>marine</strong><br />

embayment fringed by seagrass beds, rocky reefs and sandy beaches. The benthic<br />

assemblages in the muddy central region are distinct from those in the sand to the west and<br />

east. Western Port Bay and Corner Inlet are large muddy estuaries with extensive mudflats,<br />

mangroves, saltmarshes and seagrass beds (IMCRA 2006).<br />

Figure 4. A common species in the park: butterfly perch Caesioperca lepidoptera at Wilsons<br />

Promontory Marine National Park.<br />

7

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