Natural Ecosystems - The Coast
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| Between 13,000 and 20,000 years ago, at the peak of the last Ice Age, the sea level was about 100 metres lower than it is today, and Tasmania and the Bass Strait islands were connected to Victoria. As the ice retreated the sea level rose, drowning the coastal river valleys and forming the many bays and inlets that are a feature of the modern Victorian coastline. Constant exposure to the often gale-force winds that blow from the Southern Ocean has produced the rugged, eroded landforms that characterise much of the western coastline. Lashed by wind and waves, the coast is dynamic, wild, and continually changing: some features appear and disappear in a matter of months or years, unlike the millennia required for mountains to form and erode. |  |
The critical environmental factors affecting the vegetation of the coast are wind, salt, and the natural instability of many coastal landforms. The grasses and herbs which colonise the foredunes, and the saltmarsh plants and mangroves of the mudflats, bind these substrates. Coastal scrubs develop in the lee of the foredunes and on older, stabilised dunes on the landward side, usually comprising dense stands of wiry shrubs such as Coast Tea-tree, Coast Beard-heath, Drooping She-oke and Moonah. In the more protected swales between and behind the dunes, woodlands of Coast Banksia grow.
The most prominent group of coast-dwelling animals are the birds: Orange-bellied Parrots, which migrate from Tasmania and overwinter in coastal saltmarshes; Little Penguins, which nest in the dunes; and scores of migratory birds that are regular visitors to our bays and estuaries from Japan, Siberia and the northern Pacific. Australasian Fur Seals spend most of their life at sea, but use the coasts and islands to rear their young.
Most of Victoria’s coastline is reserved for public use, with extensive sections in national or state parks, so that it is relatively intact compared to the coasts of most other industrialised countries. Much of this consists of windswept sandy beaches, rocky shorelines and cliffs. Where the impact of the waves is reduced in the many embayments along the coast, other habitats have developed, including seagrass beds, mudflats, mangrove communities and saltmarsh complexes. The coastal soils are predominantly sandy, although in some areas, especially where there are cliffs and bluffs, loams and clay soils occur.
| Environmental weeds are a significant problem in many coastal areas; some exotic species readily colonise disturbed areas, while some native species have been able to expand beyond their normal range as a result of altered conditions, such as the long-term absence of fire. Pest animals such as foxes and cats are also abundant and can be a significant problem for ground-nesting birds and small mammals. Increasing coastal recreation and the urbanisation of coastal and near-coastal areas presents a challenge for the management of this ecosystem. |  |