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Barwon Bluff Marine Sanctuary

map of the barwon Bluff Marine SanctuaryBarwon Bluff Marine Sanctuary extends from the high water mark at the Point Flinders headland, locally known as “The Bluff” at the mouth of the Barwon River. It protects 17ha of predominately sandstone and sandstone reefs, thick patches of kelp and the wrecks of two ships.

The eastern half of the reef is basalt, formed from lava flow, and is exposed to the flow of the river. The western side is old sandstone and influenced by ocean swell. On the outer edges of the reef are the wrecks of two ships.

The variation in conditions across the reef results in the presence of a huge diversity of plants and animals.

Visitors can see anything from feather stars and barnacles to rock lobsters, rays and schools of fish. Bull Kelp, sandstone arches and sponge gardens create a fascinating and complex underwater world.

We acknowledge the Aboriginal Traditional Owners of Victoria – including its parks and reserves. Indigenous tradition indicates that the sanctuary is part of Country of Wadda wurrung.

Close to the township of Barwon Heads, the sanctuary extends 400 metres to the east and south of the headland. It is accessible from the shore through the Barwon Heads township or from “The Bluff” via stairways.

Friends of the Bluff undertake regular dives and walks to monitor our local marine environment and develop activities that raise the awareness of our diverse and remarkable coastal environment.

Physical Parameters and Processes

Waters to the east of Point Flinders are relatively calm, influenced predominantly by tidal currents and the flow of water from Barwon River. West of Point Flinders the intertidal platforms and beach are exposed to persistent high-energy south-westerly swells in Bass Strait.

Wind and wave action influence the beaches, affecting grain size, deposition and erosion. Natural hydrodynamic events such as storm surges displace seaweed and kelp communities, erode beaches and deposit sand over the reefs.

Surface water temperatures vary between an average 17.5°C in the summer and 13.5°C in the winter. Tidal variation is 2.1 metres for spring tides and 0.7 metres for neap tides.

The Barwon River estuary runs into Bass Strait 600 metres north of the sanctuary. Barwon Heads is geologically significant as a coastal bluff in Pleistocene dune calcarenite with interbedded palaeosoils, resting on basalt.

Marine Habitat Distribution and Ecological Communities

The main habitats protected by the sanctuary include intertidal and subtidal soft sediment, intertidal and subtidal reefs, and the water column.

The intertidal calcarenite and basalt reef is home to a variety of marine plants. The brown algae Neptune’s Necklace (Hormosira banksii) is a key habitat forming plant on these intertidal reefs. Other brown algae (e.g. Cystophora retorta; C. retroflexa) are largely found very low on the shore or in rock pools. The seagrass Amphibolis antarctica can also be found in rock pools.

Large patches of the Red Turf Algae (Capreolia implexa) can have very high cover on the intertidal reef. This alga can form a matrix with the Little Horse Mussel (Limnoperna pulex), which occurs in low abundance on the reef. Other aggregating invertebrates found at in the sanctuary include the Six-plated Barnacle (Chthamalus antennatus).

The sanctuary is home to more than thirty five species of intertidal invertebrates including anemones (e.g. Oulactis sp, Aulactinia veratra and Actinia tenebrosa) that are common in rock pools, molluscs (e.g. Bembicium nanum, Nodilittorina spCellana tramoserica, Siphonaria sp, Cominella lineolata, Dicathais orbita and Aplysia gigantean), seastars (e.g. Meridiastra calcar, and Parvulastra exigua) and shore crabs (e.g. Cyclograpsus sp and Paragrapsus sp). The ascidian Pyura stolonifera is also present on the lowest perimeter of the reef.

Common fish on the Barwon Heads intertidal platform (found in rock pools) are the Tasmanian Blenny (Parablennius tasmanianus) and the Southern Crested Weedfish (Cristiceps australis).

The shallow (mostly 5 metres) subtidal rocky reefs in the sanctuary include areas of low profile reef close to sand patches which are generally dominated by mixed brown algae. In the west and away from the sand patches, the reef becomes dominated by the brown alga Crayweed (Phyllospora comosa).

On the seaward edge of the intertidal platform Bull Kelp Durvillaea potatorum forms a narrow band approximately 10 metres to15 metres wide. Beds of Giant Kelp are found in the southern corner of the sanctuary. A variety of invertebrates are found on subtidal reefs including molluscs (e.g. Black Lip Abalone (Haliotis rubra), Warrener (Turbo undulatus), Elephant Snail (Scutus antipodes) and Cartrut Whelk (Dicathais orbita), echinoderms (e.g. Coscinasterias muricala, Tosia australisNectria sp). Also present is the ascidian and crustaceans (e.g. Red Bait Crab (Plagusia chabrus) and the Southern Rocklobster Jasus edwardsii).

At the eastern tip of the sanctuary filter-feeding invertebrates such as feather-stars and sponges are common due to the fast currents. Sea slugs (opisthobranchs) can also be found on the reef sides.

Common fish on the subtidal reefs include the Blue-throated Wrasse Notolabrus tetricus, Herring Cale, Odax cyanomelas, Scalyfin Parma victoriae, Sea Sweep, Scorpis aequipinnis, Magpie Morwong, Cheliodactylus nigripes and various leatherjackets. Sharks and rays such as the Port Jackson Shark Heterodontus portusjacksoni, Southern Eagle Ray, Myliobatis australis and Smooth Stingray Dasyatis brevicaudata have also been recorded on the subtidal reef.

Drift observed in the intertidal soft sediments provides important feeding and roosting habitat for shorebirds, many of which are of conservation significance.

The water column is home to a variety of planktonic and pelagic organisms. Those that make their permanent home in the water column include sea jellies, salps, many fish, and phytoplankton and zooplankton. A number of seabirds also use the waters of the sanctuary.

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