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Discovery Bay Marine National Park is 20 kilometres west of Portland and adjacent to Discovery Bay Coastal Park. It covers 3,050 hectares and is part of the largest coastal basalt formation in Western Victoria. There is a high diversity of intertidal and shallow subtidal invertebrates, including abalone and rock lobster. The basalt reefs are covered in kelps including the large brown kelp Ecklonia radiata. The calcarenite reefs abound with sponges, ascidians, bryozoans and gorgonians. The region is well known for whale watching and blue whales regularly pass by the area.
Discovery Bay is Victoria's marine gateway to the Great Australian Bight and the immense seas of the Southern Ocean. The cliffs of Cape Bridgewater to the east and the white sand dunes of Discovery Bay to the north frame the Discovery Bay Marine National Park. The coastline is formed from the remains of a massive volcano which spewed forth lava over the last million years, cooling into hard, basalt rock.
The seafloor of the area reflects this dynamic history. In deep water (30 to 60 metres) within the park, there are low reefs formed from ancient shorelines or dunes when the sea-levels were much lower than today. These reefs are covered in rich sponge 'gardens', composed of numerous types of sponges, filmy sea-mosses and erect sea-fans. Between the reefs, there are plains of sand winnowed into symmetrical ridges by the endless movement of water.
The rich sea-life is derived in part from cold nutrient-rich water which is sucked up to the surface by offshore winds and currents during summer. This water encourages the growth of microscopic plants and animals, providing a feast for fish and seafloor life. The profuse branching arms of sea-fans, sea-mosses and hydroids are composed of countless tiny mouths that devour passing prey. Sponges and sea-squirts filter food from sea-water through a complex system of pipes and internal chambers.
The connection to the Great Australian Bight and the Southern Ocean is emphasised by the regular visits of Southern Right Whales that migrate up from Antarctic waters in summer to breed, and sea-lions foraging from colonies in South Australia. Australian Fur Seals are common and attract the attention of Great White Sharks. Blue whales, the largest of all ocean creatures, also visit these waters on occasions.
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Fauna
Red Velvetfish (Gnathanacanthus goetzeei)
While nestled amongst kelp fronds, the Red Velvetfish is not easily seen by divers. They are more active at night and if you are lucky enough to come across one hunting for crabs and octopus on the seafloor, its red colouration is brilliant in the torchlight. In sunlight, by comparison, the fish is relatively dull as red light is rapidly absorbed in seawater. The red colouration assists camouflage on deeper reefs. Red Velvetfish have large floppy fins, scaleless bodies and soft skin and their spines are venomous. Growing to 46 centimetres, the Red Velvetfish is only found in southern Australian waters.
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Vegetation
Bull Kelp (Durvillaea potatorum)
Bull Kelp grows up to eight metres in length from their suction-cup base (the aptly named holdfast) and their wide, heavy, leathery fronds lash the rock surface bare. Bull kelp can live for up to eight years, although its life span is usually limited by storms, grazing marine animals or adverse warmer sea temperatures. Aboriginal groups used the dried Bull Kelp to transport water and food, hence the species name potatorum ('to drink').
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Looking After the Park
For the protection of the marine environment, a number of activities are prohibited within the boundaries of Victoria's marine national parks and marine sanctuaries. No fishing, netting, spearing, taking or killing of marine life. All methods of fishing, from the shore or the sea, are prohibited.
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